Abstract
Carbon nanotubes (CNTs) possess outstanding properties that could be useful in several technological, drug delivery, and diagnostic applications. However, their unique physical and chemical properties are hindered due to their poor solubility. This article review’s the different ways and means of solubility enhancement of single-wall carbon nanotubes (SWNTs). The advantages of SWNTs over the multi-walled carbon nanotubes (MWNTs) and the method of non-covalent modification for solubility enhancement has been the key interest in this review. The review also highlights a few examples of dispersant design. The review includes some interesting utility of SWNTs being wrapped with polymer especially in biological media that could mediate proper drug delivery to target cells. Further, the use of wrapped SWNTs with phospholipids, nucleic acid, and amphiphillic polymers as biosensors is of research interest. The review aims at summarizing the developments relating to wrapped SWNTs to generate further research prospects in healthcare.
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
Introduction
Carbon nanotubes (CNTs) are the novel nanostructures derived by bottom up chemical synthesis approaches [1]. They represent simplest chemical composition, atomic bonding configuration, yet exhibit the most diversity and richness among the nanomaterial in regard to structure-property relations. Solubilization and stable dispersion of these materials in aqueous solvents at high concentration is critically important to their processing and applications, as they possess outstanding properties in various emerging fields [1,2,3]. Moreover, the aqueous dispersion of these nanomaterials plays a pivotal role, regarding their use especially in biomedical research. Even after a decade of research, the full potential of employing CNTs as reinforcements has been severely limited because of the difficulties associated with dispersion of entangled CNTs during processing and poor interfacial interaction between CNTs and polymer matrix [3]. The nature of dispersion problem for CNTs is rather different from other conventional fillers, such as spherical particles and carbon fibers, because CNTs are characteristic of small diameter in nanometer scale with high aspect ratio (> 1000) and thus extremely large surface area. In addition, the commercialized CNTs are supplied in the form of heavily entangled bundles, resulting in inherent difficulties in dispersion [3].
Currently, CNTs are playing an important role in drug delivery as a carrier system because of their several unique physical and chemical properties [4, 5]. Studies show that CNTs are toxic and that the extent of that toxicity depends on their properties such as structure (single wall or multiple wall), length and aspects ratios, surface area, degree of aggregation, extent of oxidation, bound functional group(s), method of manufacturing, concentration, and dose [6]. People could be exposed to CNTs either accidentally (by coming in contact with the aerosol form of CNTs during production) or by exposure as a result of biomedical use. Numerous in vitro and in vivo studies have shown that CNTs and/or associated contaminants or catalytic materials that arise during the production process may induce oxidative stress, prominent pulmonary inflammation, apoptosis in different cell types, and induction of cytotoxic effects on lungs [5]. Targeted drug delivery is one of the key areas of research in diagnosis and rational treatment of various types of diseases. Their pharmaceutical significance and therapeutic feasibility is due to their inherent physicochemical and exceptional pharmacological activities including anticancer and antimicrobial actions [7].
In this review, the authors intend to summarize the aspects of CNTs, their types, super hydrophobicity related issues, means of improvement in solubility or dispersion, and their applications in particular to health care. Emphasis has been given to single-wall carbon nanotubes because of their superiority over multi-wall CNTs.
Carbon nanotubes
History of CNTs
CNTs are a type of carbon family materials accidentally found by Oberlyn et al. (1976) using a vapor-growth technique. These authors discovered hollow carbon tubes of nanometer-sized diameters. Later, CNTs became popular when lijima successfully clarified the structure of the nanotube and was able to grow bulk of single-wall carbon nanotubes (SWNTs) [1]. In general, carbon allotropes (pure carbon) can be categorized as graphite, diamond, fullerene (C60), and more complex structures such as carbon nanotube [2, 3] (Fig. 1).
CNTs are several micrometers long, with diameter of up to 100 nm [4]. It consists of a layer of graphitic sheet rolled up to form SWNTs with diameter ranging from 0.4 to 5 nm. A stack of single-wall nanotubes rolled to form multi-wall carbon nanotubes (MWNTs) [5] with bigger diameter from a few to tens of nanometers. Figure 2 shows the structure of SWNTs and MWNTs [9]. CNTs are able to form fullerene [6], a carbon sheet with the two end caps of SWNTs joined together. CNT has remarkable physical, thermal, electrical, mechanical, and optical properties [7] due to its strong sp2 hexagonal pattern which is a basic structure for other sp2 carbon allotropes. The carbon sp2 atoms are pyramidalized and the π-orbitals seem misaligned [8] that gives rise to the unexceptional strong properties of CNTs.
Regardless of their beneficial properties, CNTs are known to show signs of toxicity when inhaled and used as carrier for the administration of drugs for different case of human diseases. The nanotubes could affect, distribute, and deposited within the lung compartments. This could cause an inflammatory to the lung and the respiratory tract [5]. The toxicity effect was subjected to the structure (SWNTs, MWNTs, functionalized SWNTs, or functionalized MWNTs), length and surface area, extent of oxidation, and bound of functional groups. Both SWNTs and MWNTs might induce apoptosis in different type of cells [10, 11]. However, a few studies showed a low toxicity of MWNTs compared to SWNTs, whereas functionalized SWNTs (f-SWNTs) proposed low toxicity toward living cells [12]. The toxicological assessments need to be carried out and fully explored to develop understanding on their effects in biological environment.
CNTs are known to have poor solubility in organic and polar solvents. They possess a π-system with highly hydrophobic surface and tend to entangle due to strong van der Waals interactions. Two mechanisms have been proposed to increase the solubility of CNTs which are covalent modification by attaching molecules to the CNT sp2 backbone and non-covalent modification of CNTs by adsorption of molecules onto the nanotube surface [13, 14]. The non-covalent modification method is more preferable prior to its ability to preserve the intrinsic properties of nanotubes, whereas the other method caused alteration of the tube sidewall which damaged the nanotubes properties [15, 16].
In the present review, the authors focus on SWNTs owing to several advantages over MWNTs characteristic. Table 1 shows the differences in characteristics of SWNTs and MWNTs [9]. An attempt has been made to review the properties of SWNTs and its solubility enhancement with non-covalent mechanism using polymer.
Single-walled carbon nanotubes
SWNT is a rolling sheet of graphene (Fig. 2) along an (n, m) lattice vector in the graphene plane and formed a cylindrical tube with diameter of about 1–2 nm. The (n, m) lattice vector determines the diameter and chirality [9]. SWNTs can be either metals or semiconductors depending on the chirality (Fig. 3) [6, 17]. Following the general opinion, SWNTs are named as zigzag when m = 0, armchair when n = m, and other state are called chiral [9]. The armchair form is usually having metallic behavior, whereas the other form commonly acts as a semiconductor. The small diameter semiconducting SWNT (s-SWNT) and large diameter metallic SWNT (m-SWNT) are approximately two-third and one-third of SWNTs production, respectively.
SWNTs can be synthesized and purified altogether through method of dual pulsed laser vaporization [18] that purified SWNTs in a large scale and arc discharge [19] method involving combination of acid washing followed by a high temperature hydrogen treatment. These treatments successfully remove amorphous carbon, clean the SWNT, and yield purified SWNTs. In advanced method, s-SWNT and m-SWNT can be separated using chemical vapor deposition (CVD) growth of SWNTs [20] with 90% purity and a defined chirality along with controlled structures. The separation was done by using special scotch tape composed of polydimethylsiloxane (PDMS) as supporting material and 3-aminopropyl-triethoxysilane (C3H23NO3Si, APTES) and triethoxyphenylsilane (C12H20O3Si, PTEOS) as functional glues for s-SWNT and m-SWNT respectively.
Recently, Hou et al. (2014) have reported that modified floating catalyst chemical vapor deposition method (FCCVD) using hydrogen gas as the selective etchant has positively removed s-SWNTs and yielded about 88% of m-SWNTs. The exact yield of m-SWNTs without s-SWNTs offered great potential applications in high-performance transparent conductive devise [21]. The ability to control the diameter and chirality of nanotubes has been in demand for structural control and specific application in certain devices, which can be achieved by adjusting the furnace temperature or selecting a suitable catalyst [22, 23]. Soumyendu et al. [24] proposed an ordinary process of CVD with a lower concentration of catalyst used and has reduced the diameter spread of the SWNTs synthesized from 1.65 to 1.13 nm. The main advantage of this method is because of its simplicity.
The diameter of SWNT can be enlarged on purpose by heat-treatment. The tubes were heat-treated in vacuum of 10−6 Torr for 5 h in the temperature range of 1000–2000 °C [25]. Later, at 1800 and 2000 °C, a few SWNTs with diameters of about 1.53 and 1.75 nm have appeared. Two years later, Yudasaka et al. further investigated the effect of heat treatment using HiPco SWNT and single-wall carbon nanohorn (SWNH) heated at 1000–2400 °C that resulted in the formation of multi-wall carbon nanotubes at higher temperature specifically at temperature more than 2000 °C [26]. Similarly, Yudasaka et al. (2003) have attempted to incorporate a guest molecule namely C60 inside the enlarged tube of SWNT via methods of nano-extraction and nano-condensation. The method involved heat-treated HiPco SWNT at 1780 °C in vacuum producing SWNT with diameter from 1 to 2 nm. The sample then treated with C60 crystallite into 10 ml of ethanol and ultrasonicated for 3 min [27]. The so-called nano-extraction method is easy to apply while the nano-condensation method is very convenient as the process is faster.
Medicinal properties of SWNTs
Utility in medicine and health
The use of carbon nanotubes in medicine and health has gained greater attention from researchers. CNTs play important roles in drug delivery system (DDS) as successful nanocarrier since their hollow tube provide spaces for small molecules to be incorporated inside it [27,28,29]. This will open novel path in DDS as drug moieties can be loaded inside the hollow tube and delivered to target cells [30]. Arsawang et al. (2010) have investigated the molecular properties of the encapsulated anticancer drug gemcitabine inside SWNTs via molecular dynamics (MD) simulation [31], which showed that the drug molecule always exists in the tube through the π-π stacking conformation formed between its cytosine ring and the tube surface. SWNTs are found to be well conjugated with many therapeutics [32], able to release the drug moieties inside cells [33], and more versatile because of their superior property in penetrating cells including hard and transfect types of cells [34]. They work fine for bioimaging [35], biosensing [36], and biomedical applications [37].
As reported, SWNTs can be internalized into cells via phagocytosis and endocytosis [38, 39] supporting delivery of medicine into a targeted cell. A stable PEGylated-nanotube with doxorubicin incubated with Hela cells showing localization within endosomes that suggests engulfment of drug-SWNTs complexes in endosomes [40]. Besides, SWNTs were also able to cause cell apoptosis which is a favorable characteristic to kill cancer cells [10]. SWNTs upon exposure to laser light can cause SWNTs sheets to adsorbed water molecules and heated to more than 100 °C that caused nanobomb. The nanobombs in the study showed specific explosion to the human BT474 breast cancer cells treated with SWNTs while the untreated surrounding cells were viable [41].
Lee and co-workers (2013) have developed a conjugated cetuximab-SWNTs (SWNTs-c225) linked to poor solubility chemotherapeutic drug [42, 43] SN38 (7-ethyl-10-hydroxycamptothecin), a topoisomerase I inhibitor that has strong toxicity against various types of cancer cell such as lung, colorectal, and ovarian. The conjugated drug had successfully overcome the poor solubility disadvantage of SN38 by using SWNTs as the delivery vehicle. Three different over-expressed colorectal cancer cell lines (HCT116, HT29, and SW620) were used to study the anticancer agent SN38 using the SWNTs carrier. The result showed that the intracellular SN38 was first dissociated from the SWNT carrier before entering the nucleus while SWNT-carrier remained in the cytoplasm. The active drug was released enzymatically and caused cell apoptosis of HCT116, HT29, and SW620 cells after 72 h of incubation [44].
Another study on cancer treatment had been reported by Liu et al. (2008) when their water-soluble conjugated SWNTs with paclitaxel (SWNTs-PTX), a cancer therapeutic drug, showed higher efficiency in suppressing tumor growth in murine 4T1 breast cancer model compared to clinical Taxol [45]. The in vivo study can be classified as successful due to prolonged blood circulation and ten-fold higher uptake of PTX by the tumor cells that result in cell apoptotic. Besides, SWNTs were found excreted through biliary pathway which is promising for cancer treatment as it possessed minimum side effects with low drug doses for cancer therapy.
As the safety of CNTs is a growing concern, many researchers have investigated the toxicity of CNTs [46, 47]. Treatment of two types of SWNTs (single and double walled) and MWNTs-50 on 24 male Wistar rats showed over 500 μm fibrotic lesions in MWNTs-50 treatment. This massive fibrosis was not observed in both types of SWNTs but observed in MWNTs-50 (Fig. 4a) which suggest that SWNTs had lower carcinogenicity to mesothelial cells [48]. Recent study showed that MWNTs possess huge behavioral toxicity such as anxiety and depression compared to SWNTs [46]. Meanwhile, SWNTs at lower concentration showed significant Chinese Hamster Ovarian (CHO) cell survivor with minimal changes in the cell morphology and cell numbers (Fig. 4b) [49].
The study of SWNTs in DDS has not stopped and it is on-going. Donkor and Tang (2013) reported that SWNTs that underwent extended period of acid treatment for 32 and 44 h lead to ultra-short SWNTs (US-SWNTs) [50] with an approximate yield of 77% of SWNTs above 35 nm and over 80% within 10–35 nm length. Two systems of US-SWNTs (SWNTs-30 and SWNTs-50) with lengths of 30 and 50 nm respectively and linked covalently with 6-arm polyethylene glycol (PEG) showed better cellular uptake for active targeting. Depending on the cell type, SWNT-30 showed spontaneous cellular uptake for active targeting and rapid excretion out of Hela and hepatoma but not Huvec cells (Fig. 4c). Hence, this results in the prevention of intracellular accumulation of SWNTs that could lead to toxicity.
Single-walled carbon nanohorns (SWNHs) have been investigated as drug carrier due to their horn-shaped single-walled graphene sheets [51]. SWNHs incorporating with cisplatin forming CDDP@SWNHox is an anti-cancer drug that had the potential to kill human lung-cancer cells, NCI-H460 [30]. The cisplatin released from CDDP@SWNHox was able to reduce the proliferation of NCI-H460 cells, whereas the carrier SWNHox showed non-toxic behavior against non-cancer cells. Iijima et al. (2014) reported that SWNHs with gadolinium oxide (GD) when orally administered to normal and colitics-induced mice showed that black SWNHs particles were only found in the gastrointestinal tract and feces (Fig. 4d) but not in the spleen, blood, or liver thus preventing the accumulation of SWNHs in the body that would have caused toxicity [52]. However, this result is contradicted with the article reported by Han et al. (Fig. 4e) [53]. The summary of medicinal utility of CNTs has been presented in Table 2.
Antimicrobial properties of SWNTs
SWNTs have also been investigated to treat microbes and surprisingly SWNTs showed strong antimicrobial activity (Fig. 5a, b) [54] and antiseptic properties [55]. SWNTs have become potent candidates to treat multidrug-resistant microorganisms such as viruses, bacteria, fungi, and protozoa that caused microbial infection and mortality globally [56]. The discovery of antimicrobial properties of SWNTs gives hope for application of functionalized carbon nanotubes (f-CNTs) as carrier for antibiotics to overcome resistant developed by microorganisms toward antibiotics and enhance their bioavailability and provide their targeted delivery [57].
Functionalized SWNTs (f-SWNTs) with –OH and –COOH groups appear to show a strong antimicrobial activity toward both gram-negative and gram-positive bacterial cells [58] by disrupting the microorganism cellular membrane integrity, metabolic processes, and morphology. Later, Pasquini et al. (2012) reported that surface functionalization of SWNTs with nine different functional groups had showed different aggregation state and dispersity that indirectly affect the bacterial cytotoxicity [59]. Conjugation of SWNTs with a widely known metal that possess antimicrobial properties like silver has been attributed to strong bactericidal against both mucoid and nonmucoid strains of Pseudomonas aeruginosa [60]. It is the first report of antimicrobial activity of AgCNTs against a mucoid variant of P. aeruginosa a more virulent phenotype that normally causes human infections.
Effects of SWNTs length and concentration on the antimicrobial properties of SWNTs were studied by Yang et al. [61] and Le et al. [62] respectively. SWNTs owing metallic properties showed better antimicrobial activity against Escherichia coli cells compared to semiconducting SWNTs [63]. The unique properties of SWNTs were not only studied by microbiologist but also by ecotoxicologist [64]. Besides, single- and double-wall carbon nanotubes were also used as the removal of antibiotics from aqueous solution with highest removal capacity was achieved by using SWNTs compared to MWNTs [65]. This result is crucial in controlling and treating aquatic pollution caused by pharmaceutical drugs and surfactant.
Super hydrophobicity of SWNTs and related issues
SWNTs like other nanotubes are naturally highly hydrophobic and cannot dissolve in the aqueous environment [66]. The strong hydrophobicity, π-π stacking, and the van der Waals attraction within the nanotubes system support cluster of SWNTs formation. These bundled SWNTs have hindered them from solubilizing in organic solvents and water-based systems [67]. The incapability to solubilize might restrict or prevent their use in most promising applications especially in biological systems including drug delivery, biosensors, biomedical devices, and cell biology [68].
Strategies to enhance solubility
Dispersing individual SWNTs in water or other solvents is critical for biological applications and certain composite material applications. Dispersing SWNTs without the aid of a solubilizing agent seems to be impossible due to a strong van der Waals interaction of the nanotube particles. Initially, SWNTs are insoluble in any type of solvent until recently, where organic functionalization by modifying the sidewalls and linking them with chemical substances has increased the solubility of SWNTs [34]. SWNTs have various utility in the physical and biological environment. However, the low aqueous solubility of SWNTs poses a major hindrance for its usage in those environments. Solubility of SWNTs can be enhanced by covalent functionalization (Fig. 6) [34] and non-covalent wrapping with surfactants, peptides, and polymers [69,70,71]. The method of non-covalent wrapping is found to be a simple way of SWNTs solubilization.
Covalent functionalization involves methods of acid oxidation of SWNTs. This method is designed specially to remove carbonaceous and metal particulate impurities but somehow it introduces functional groups such as carboxylic groups and other oxygen-bearing groups to the side wall or end of nanotubes [72] which contribute to SWNTs solubility. The method often caused shortening of the tube [73], alteration of the intrinsic property, and modification of the nanotubes sidewall. In contrast to covalent functionalization, the non-covalent method of SWNTs is safer and more preferable because it preserves the nanotube aromatic surface and its intrinsic properties [74]. Most of the solubilizing agents are not directly attached to the damaged nanotube sidewall but only adsorbed to it. This is often a better way for one to tailor properties with intrinsic traits remaining unchanged.
Functionalization versus wrapping of SWNTs
The concepts about
Both methods of functionalized and wrapping of SWNTs are powerful to increase solubility of SWNTs in many solvents. Researchers have reported that SWNTs possess a high turnover in functionalization [38] that increases their dispersion in the aqueous solution. Buffa et al. (2005) performed the sidewall functionalization of SWNTs with hydroxymethylaniline (HMA) followed by the polymerization with poly-ϵ-caprolactone (PCL) and achieved better solubilization of SWNTs in chloroform [75]. The polystyrene (PSt) functionalized SWNTs lead to their increased solubilization in organic solvents. This phenomenon has been further supported by the atomic force microscopy (AFM) microphotograph of the former in the form of broken individual ropes (Fig. 7) [76]. Polyimide (PI-NH2) functionalized SWNTs have been synthesized to achieve their greater dispersion, hence being utilized for the preparation of composite films [77]. However, covalent modification of SWNTs causes permanent change in structure, from sp2 to sp3 orbital hybridization that may result in optical, electrical, and mechanical deterioration [78].
A non-covalent approach comprises of micellar formation and wrapping technique of SWNTs with hydrophilic substances such as surfactants, deoxyribonucleic acid (DNA), peptide, and polymer [79, 80]. This technique is preferred because it preserves the electronic conjugation of the rolled graphene sheet [81] as well as dispersing and preventing them from forming bundles and ropes. Surfactants’ structures are very diverse with different modes of action. For example, charged surfactants such as sodium dodecylsulphate (SDS) and tetraalkylammonium bromide stabilize nanotubes by electrostatic repulsion between micelles [81, 82] and charged-neutral surfactants or non-ionic surfactants such as poly(vinylpyrrolidone) (PVP) acts by assembling around the nanotube due to the large solvation shell created by the hydrophilic part (as shown in Fig. 8) [80].
Advantages of wrapping over functionalization
The main advantage of wrapping over functionalization is that it can minimize strain in the conformation of polymer-SWNTs by wrapping it in a helical fashion [83, 84]. It is known that wrapping nanotubes with polymer reduces the entropic penalty of micellar formation. Some conjugated polymers showed significantly higher energy of interaction with nanotubes compared to small molecules with nanotubes which result in better solubilization of SWNTs in solvents. Advantages and disadvantages of the wrapping and functionalization method are summarized in Table 3.
Polymer-wrapped SWNTs
Wrapping with chronological view point
The work of wrapping of SWNTs with polymers was started more than a decade ago. The work was first established to study the interaction of π-π backbone and van der Waals forces of the polymer and SWNTs side wall that presumably enhance solubility of SWNTs without disrupting the π-system of the tube. It started with SWNTs’ wrapping with poly{(m-phenylenevinylene)-co-[(2,5-dioctoxy-p-phenylene)vinylene]} (PmPV) a type of polymer that can wrap itself around the nanotube. However, this polymer is inflexible and less efficient in segregating bundles of SWNTs that requires more polymers for more nanotube solubilization [85]. An improvised polymer with hyper-branched molecule was prepared by self-polymerization of ABX monomers. The synthetic hyperbranched polymer using dendrimer proposed more dispersion of single-strands SWNTs as observed on a mica wafer [83].
The wrapping of water-soluble polymers, poly(ethylene glycol) (PEG), and poly(vinyl alcohol) (PVA) onto SWNTs has been tried, but it was not successful [86]. Using a nontoxic and simple technique [87] called supercritical carbon dioxide (SC CO2) antisolvent-induced polymer epitaxy (SAIPE) method, Zhang et al. (2008) proposed PEG and PVA being effectively wrapped onto SWNTs (Fig. 9a–c) [88] forming nanohybrid shish-kebab (NHSK) structure by using lower concentration of SWNTs approximately about 0.002 wt%. Using the same method (SAIPE) but different experimental conditions, Zhang et al. (2008) have managed to obtain structure of SWNTs being wrapped with PEG10000 in helical style which had been proved by Smalley et al. (2001) in his previous study [86]. He reported that the water-soluble polymer poly(vinylpyrrolidone) (PVP) was wrapping SWNTs helically and later Kang et al. [89] proved the helical wrapping of poly(p-phenyleneethynylene) (PPES) with SWNTs (Fig. 10).
Caddeo et al. (2010) have studied the molecular dynamics of simulation helical wrapping of poly(3-hexylthiophene) (P3HT) interact with SWNTs [90]. From the simulation, it is proven that neighboring polymer chains stabilize the helical wrapping and the nanotube chirality does affect the coiling angle and the helix morphology. A schematic summary of three-steps’ structural changes of non-aromatic poly(dialkylsilane) (Psi1a) wrapping on SWNTs have been reported by Chung et al. (2013) and isolated SWNTs were rapidly mixed in N,N-dimethylformamide (DMF) to initiate spontaneous wrapping. Psi showed selectivity to SWNTs with diameter of 0.9 nm resulting in specific wrapping toward (7, 6) and (9, 4) SWNTs (Fig. 11) [91]. The result was first monitored with the stopped-flow technique. Deria et al. (2013) have proposed that helical wrapping of SWNTs by chiral and highly charged binaphthelene (BN)-based semiconducting polymers resulted in both left-handed (expected) and right-handed (unexpected) helical structure wrapping on SWNTs [92].
Researchers continuously prompted studies regarding methods to solubilize nanotubes in polar and non-polar solvents without altering the nanotube system. A well-known redox mediator often used for biosensing, ferrocene, or its conjugate polymer known as polyvinylferrocene (PVF) was used to control both SWNTs and MWNTs dispersion and reprecipitation in organic liquid as it demonstrates redox-switchable affinity for chloroform with the use of ferum (III) chloride (FeCl3) and potassium iodide (KI) [93] to oxidize and reduce respectively of the ferrocene. The complete coprecipitation of CNTs and PVF upon oxidation was confirmed with electrochemical process when CNTs and PVF codeposited on the electrode surface during switchable redox transformation.
Using conjugated polymers to study the solubility of SWNTs with different mechanisms has become popular. Liu et al. [87] have investigated the formation of conjugated polymer nanowires (CPNWs) on SWNTs which was similar to that of hybrid shish-kebab [87] and theoretical formulation of centipede-like supramolecular CPNWs-CNTs structure [94]. Unlike Liu et al. [87], Liang et al. [95] have prepared a stable dark polymer-SWNT solution with no flocculation observed over several months by adding 3 mg of raw SWNTs powder into 50 mg of tetrathiafulvalene copolymerized with fluorene (TTFV-fluorene) solution in toluene (sonicated). TTFV-fluorene copolymer exhibits switchable conformational changes upon protonation with trifluoroacetic acid (TFA) and results in the formation of SWNTs precipitates after being successfully dispersed in toluene. The release of SWNTs from its copolymer enables the recovered polymer to be used again to redisperse the precipitated SWNTs [95]. This demonstrates that the dissolution-precipitation process is reversible.
Solubilizing SWNTs in different types of solvents is very important for different practices. Aggregation of SWNTs in many solvents, mainly in more polar solvents such as water, has hindered their applicability in biological applications. The solute solvent interactions study of polyvinyl pyrrolidone-wrapped SWNTs (PVP-SWNTs) carried out by Mohamed et al. (2013) proves that the polymer-SWNTs are soluble in water [71]. The interaction of the solute (PVP-SWNTs) and solvent (water) was studied using viscometric studies [96] and acoustic methods [97]. These studies mainly emphasized on the viscosity, and ultrasonic velocity and density respectively. Summary of the polymer-wrapped SWNTs were summarized in Table 4.
Mechanisms of polymer wrapping
Polymer wrapping of SWNTs can be achieved via introducing the nanotubes to aromatic polymers or non-aromatic polymers. The aromatic polymers such as DNA and PSi’s have the π-π interactions between the polymers and the curve surface of SWNTs that played a crucial role for the chiral separation. The aromatic polymers formed a self-assembled single layer adopted the trans-zigzag conformation in which they can spontaneously bind on the cylindrical graphene sheet of SWNTs with specific chiral indices even without π-π interactions [91]. While polymers without the aromatic moieties such as PVP have the weak noncovalent interaction (CH-π and Van der Waals forces) to serve as the driving force to stimulate the spontaneous wrapping [98]. Meanwhile, the stability of the helical wrapping and the nanotube chirality were supported by the neighboring polymer chains [90].
The disruption of the hydrophobic interface between the aggregated nanotubes and the aqueous medium by wrapping of SWNTs with water-soluble polymer is found to be driven largely by a thermodynamic factor. The favorable enthalpy interaction gives a maximum free energy penalty for SWNT-wrapped polymer conformational restriction at 25 °C of 17 kJ/mol nm. The loss of the hydrophobic surface was achieved by shielding the nanotube from the water in which it is immersed, and was estimated from the surface tension of the corresponding hydrophobic cavity. In other mean, the regular wrapping arrangement was smaller than the gain achieved by overcoming the hydrophobic penalty between the SWNTs and their surrounding water [82].
Utility of polymer-wrapped SWNTs
Polymer-wrapped SWNTs have been used in biomedical applications as they are biocompatible with the aqueous environment. Generally, the polymer-wrapped carbon nanotubes in drug delivery reveal low toxicity, sustained drug release, and persist in circulation without aggregation [99]. Earlier, researchers tried using SWNTs-fluorophore/dye molecules to penetrate the cell membrane for biomedical imaging. Fluorophore and dye molecules have both hydrophobic and hydrophilic moieties. They are able to interact with SWNTs and increase the tubes solubility with different efficiency. Koh et al. (2012) have reported that SWNTs with different types of fluorophores showed different levels of cell transfection efficiency with fluorescein isothiocyanate (SWNTs-FITC), which showed the highest penetration into cells (Fig. 12a) compared to other fluorophores [100]. Chen et al. (2008) have reported that biotin-SWNTs-FITC conjugates showed specificity to cancer cells, overexpressing biotin receptors on the cells surface and are able to release taxoid molecules inside the cancer cells [101]. The synthesized biotin-SWNTs-FITC was incubated with leukemia cell lines (L1210FR) for 3 h to induce endocytosis (Fig. 12b) which showed better fluorescent. The cellular uptake of bio-conjugate SWNTs may be beneficial to deliver molecules that have difficulty in penetrating cell membrane.
Malignant cells could have a better procurement with early detection by using methods of imaging and sensoring [102]. SWNTs with cellular imaging properties have clearly diagnosed and differentiated malignant from non-malignant cells [103]. SWNTs wrapping with different polymers such as phospholipids, nucleic acids, and amphiphilic polymers perform as biosensors for detection of neurotransmitter. Neurotransmitters play a major role of neurotransmission in chemical synapses [104] and a central part of data processing in the brain. Kruss et al. (2014) have studied a new technique named corona phase molecular recognition (CoPhMoRe) which is used to identify adsorbed polymer on fluorescence SWNTs that allows selective detection of neurotransmitters including dopamine [105]. These authors report that DNA- and RNA-wrapped SWNTs showed better fluorescent-turn on sensors with an increase in fluorescence from 11 to 80% upon the addition of dopamine.
CNTs with thermal property afford a new insight in photothermal therapy of tumors when conventional surgery is not possible. The nanoparticles are used to convert near-infrared (NIR) radiation to vibrational energy and produce sufficient heat to kill cancer cells [106]. Single-walled carbon nanotubes with the help of a designated peptide, H(-Lys-Phe-Lys-Ala-)7-OH (KFKA)7 forming SWNT-(KFKA)7 peptide composite. It was used to reduce the proliferation of tumor cells [107]. The study was carried out in vitro and in vivo using the cell culture of murine rectum (colon 26) and human hepatocellular carcinoma cell lines (HepG2). In vitro and in vivo intratumoral injection of colon 26 tumor into healthy murine was made. The in vitro experiment showed a large number of tumor cells death in both cell lines when SWNTs-(KFKA)7 and NIR irradiation were delivered to the cell culture. The in vivo experiment showed effective therapeutic effect of SWNTs-(KFKA)7 plus NIR irradiation against colon 26 tumor. The NIR irradiation increased rapidly the temperature of the tumor tissues treated causing reduction of tumor growth (Fig. 12c).
NIR irradiation has been suggested as a non-invasive and harmless skin-penetrated radiation which provides safe thermal ablation therapy for cancer cells [103]. SWNTs have become potent candidates for photothermal therapy due to their photon-to-thermal conversion property that generates a significant amounts of heat when employed with NIR light (NIR, λ = 700–1100 nm). Moon et al. (2009) have covalently functionalized Hipco SWNTs with PEG2000 preparing a PEG-SWNTs solution. The solution was then injected intra-tumorally into the nude mice bearing human epidermoid mouth carcinoma tumor cells and irradiated with NIR light for 3 min. After 20 days, the result showed complete destruction of tumors with one observable black round marks on the mice skin (heating effects from PEG-SWNTs with NIR radiation) (Fig. 12d) while the control showed proliferation of tumor cells that led to mice death. The treated mice showed no recurrence of tumor over 6 months with positive result of PEG-SWNT excretion from the body [108].
Future prospects
Wrapping of SWNTs with polymers adopting non-covalent approach using suitable polymers should be of interest due to their hydrophobic alkyl backbone and hydrophilic pendant groups that can coil around the nanotube where the backbone keeps contact with the nanotube and hydrophillic group exposed to water. The polymer-wrapped SWNTs with enhanced solubility in water will have great utility in biological environments. They can be further investigated as a drug carrier to the targeted site. Further toxicological studies relating wrapped SWNTs are of particular importance.
Summary
In the present review, we provide the details of the non-covalent wrapping of SWNTs with polymer including the advantages over the method of functionalization. The method consistently shows improvement of aqueous dispersion of SWNTs in aqueous media, hence the resultant improvement in the different field of applications. The antimicrobial and applications in the areas of health care are highlighted. Yet this review of the previously carried out research clearly suggests the future endeavor needed in the directions of the development of better therapeutic modalities using the several nano-technological means giving due importance to the absorption, distribution, metabolism, and excretion of the wrapped SWNTs.
References
Iijima S, Ichihashi T. Single-shell carbon nanotubes of 1-nm diameter. Nature. 1993;363:605–6.
Hodkiewicz J. Characterizing Carbon Materials with Raman Spectroscopy. Scientific TF.
Ma PC, Siddiqui NA, Marom G, Kim JK. Dispersion and functionalization of carbon nanotubes for polymer-based nanocomposites: a review. Compos Part A Appl Sci Manuf. 2010;41(10):1345–67.
Tasis D, Tagmatarchis N, Bianco A, Prato M. Chemistry of carbon nanotubes. Chem Rev. 2006;106:1105−1136.
Kayat J, Gajbhiye V, Tekade RK, Jain NK. Pulmonary toxicity of carbon nanotubes: a systematic report. Nanomedicine. 2011;7(1):40–9.
Dresselhaus S. Physics Of Carbon Nanotubes. 1995;33(7):883–91.
De Volder MFL, Tawfick SH, Baughman RH, Hart AJ. Carbon nanotubes: present and future commercial applications. Science. 2013;339(6119):535–9.
Britz DA, Khlobystov AN. Noncovalent interactions of molecules with single walled carbon nanotubes. Chem Soc Rev. 2006;35(7):637–59.
Eatemadi A, Daraee H, Karimkhanloo H, Kouhi M, Zarghami N, Akbarzadeh A, et al. Carbon nanotubes: properties, synthesis, purification, and medical applications. Nanoscale Res Lett. 2014;9(1):393.
Cui D, Tian F, Ozkan CS, Wang M, Gao H. Effect of single wall carbon nanotubes on human HEK293 cells. Toxicol Lett. 2005;155(1):73–85.
Bottini M, Brucknera S, Nika K, Bottini N, Bellucci S, Magrinic A, et al. Multi-walled carbon nanotubes induce T lymphocyte apoptosis. Toxicol Lett. 2006;160(2):121–6.
Apartsin EK, Buyanova MY, Novopashina DS, Ryabchikova EI, Filatov AV, Zenkova MA, et al. Novel multifunctional hybrids of single-walled carbon nanotubes with nucleic acids: synthesis and interactions with living cells. ACS Appl Mater Interfaces. 2014;6(3):1454–61.
Abanulo DC, Papadimitrakopoulos F. Isotopically induced variation in the stability of FMN-wrapped carbon nanotubes. ACS Langmuir. 2013;29:7209–15.
Lobez JM, Afzali A. Surface-selective directed assembly of carbon nanotubes using side-chain functionalized poly(thiophene)s. Chem Mater. 2013;25(18):3662–6.
Xu L, Ye Z, Siemann S, Gu Z. Noncovalent solubilization of multi-walled carbon nanotubes in common low-polarity organic solvents with branched Pd-diimine polyethylenes: effects of polymer chain topology, molecular weight and terminal pyrene group. Polym (United Kingdom). 2014;55(14):3120–9.
Zhao W, Song C, Pehrsson PE, Di VC, Na V. Water-soluble and optically pH-sensitive single-walled carbon nanotubes from surface modification. J Am Chem Soc. 2002:12418–9.
Dai H. Carbon nanotubes: synthesis, integration, and properties. Acc Chem Res. 2002;35(12):1035–44.
Rinzler AG, Liu J, Dai H. Large-scale purification of single-wall carbon nanotubes: process, product, and characterization. Appl Phys A Mater Sci Process. 1998;67(1):29–37.
Src V, Govindaraj A. A new method of preparing single-walled carbon nanotubes. Proc Indian Acad Sci (Chem Sci). 2003;115:509–18.
Chen Y, Zhang J. Chemical vapor deposition growth of single-walled carbon nanotubes with controlled structures for nanodevice applications. Acc Chem Res. 2014;47(8):2273–81.
Hou PX, Li WS, Zhao SY, Li GX, Shi C, Liu C, et al. Preparation of metallic single-wall carbon nanotubes by selective etching. ACS Nano. 2014;8(7):7156–62.
Kataura H, Kumazawa Y, Maniwa Y, Ohtsuka Y, Sen R, Suzuki S. Diameter control of single-walled carbon nanotubes. Carbon. 2000;38:1691–7.
Yu S, Devaux X, Mcrae E, Yu S, Tsareva, Devaux XA, McRae EA, Aranda LA, Gregoire B, Carteret C, Dossot M, Lamouroux V, Fort S, Humbert B, Mevellec JY. A step towards controlled-diameter single walled carbon nanotubes. Carbon 67 2013;7: 753–765.
Roy S, Bajpai R, Soin N, Sinha S, Mclaughlin JA, Misra DS. Applied surface science diameter control of single wall carbon nanotubes synthesized using chemical vapor deposition. Appl Surf Sci. 2014;321:70–9.
Yudasaka M, Kataura H, Ichihashi T, Qin L-C, Kar S, Iijima S. Diameter enlargement of HiPco single-wall carbon nanotubes by heat treatment. Nano Lett. 2001;1(9):487–9.
Yudasaka M, Ichihashi T, Kasuya D, Kataura H. Iijima S, Structure changes of single-wall carbon nanotubes and single-wall carbon nanohorns caused by heat treatment. 2003;41:1273–80.
Yudasaka M, Ajima K, Suenaga K, Ichihashi T, Hashimoto A, Iijima S. Nano-extraction and nano-condensation for C60 incorporation into single-wall carbon nanotubes in liquid phases. Chem Phys Lett. 2003;380(1–2):42–6.
Jiang Y, Li H, Li Y, Yu H, Liew KM, He Y, et al. Helical encapsulation of graphene nanoribbon into carbon nanotube. ACS Nano. 2011;5(3):2126–33.
Zhang ZS, Kang Y, Liang LJ, Liu YC, Wu T, Wang Q. Peptide encapsulation regulated by the geometry of carbon nanotubes. Biomaterials. 2014;35(5):1771–8.
Ajima K, Yudasaka M, Murakami T, Maigne A, Shiba K, Iijima S. Carbon Nanohorns as anticancer drug carriers. ACS. Mol Pharm. 2005;2(6):475–80.
Arsawang U, Saengsawang O, Rungrotmongkol T, et al. How do carbon nanotubes serve as carriers for gemcitabine transport in a drug delivery system? J Mol Graph Model. 2011;29(5):591–6.
Albini A, Mussi V, Parodi A, Ventura A, Principi E, Tegami S, et al. Interactions of single-wall carbon nanotubes with endothelial cells. Nanomedicine Nanotechnology, Biol Med. 2010;6(2):277–88.
Wu CH, Cao C, Kim JH, Hsu CH, Wanebo HJ, Bowen WD, et al. Trojan-horse nanotube on-command intracellular drug delivery. Nano Lett. 2012;12(11):5475–80.
Klumpp C, Kostarelos K, Prato M, Bianco A. Functionalized carbon nanotubes as emerging nanovectors for the delivery of therapeutics. Biochim Biophys Acta. 2006;1758(3):404–12.
Chen M, Design YM. Development of fluorescent nanostructures for bioimaging. Prog Polym Sci. 2014;39(2):365–95.
Ma Y, Ali SR, Dodoo AS, He H. Enhanced sensitivity for biosensors: multiple functions of DNA-wrapped single-walled carbon nanotubes in self-doped polyaniline nanocomposites. J Phys Chem B. 2006;110(33):16359–65.
Gong H, Peng R, Liu Z. Carbon nanotubes for biomedical imaging: the recent advances. Adv Drug Deliv Rev. 2013;65(15):1951–63.
Berdjeb L, Pelletier É, Pellerin J, Gagné J, Lemarchand K. Contrasting responses of marine bacterial strains exposed to carboxylated single-walled carbon nanotubes. Aquat Toxicol. 2013;144-145:230–41.
Kesharwani P, Ghanghoria R, Jain NK. Carbon nanotube exploration in cancer cell lines. Drug Discov Today. 2012;17(17–18):1023–30.
Heister E, Neves S, Lamprecht C, Silva SRP, Coley HM, McFadden J. Drug loading, dispersion stability, and therapeutic efficacy in targeted drug delivery with carbon nanotubes. Carbon. 2012:622–32.
Panchapakesan B, Lu S, Sivakumar K, Teker K, Cesarone G, Wickstrom E. Single-wall carbon nanotube nanobomb agents for killing breast cancer cell. NanoBiotechnology. 2005:133–40.
Storm PB, Moriarity JL, Tyler B, Burger PC, Brem H, Weingart J. Polymer delivery of camptothecin against 9L gliosarcoma : release, distribution, and efficacy. J Neuro-Oncol. 2002;56:209–17.
Kawano K, Watanabe M, Yamamoto T, Yokoyama M, Opanasopit P, Okano T, et al. Enhanced antitumor effect of camptothecin loaded in long-circulating polymeric micelles. J Control Release. 2006;112(3):329–32.
Lee PC, Chiou YC, Wong JM, Peng CL, Shieh MJ. Targeting colorectal cancer cells with single-walled carbon nanotubes conjugated to anticancer agent SN-38 and EGFR antibody. Biomaterials. 2013;34(34):8756–65.
Liu Z, Chen K, Davis C, Sherlock S, Cao Q, Chen X, et al. Drug delivery with carbon nanotubes for In vivo cancer treatment. American Association for Cancer Research. 2008;68(16):6652–60.
Gholamine B, Karimi I, Salimi A, Mazdarani P, Becker Le. Neurobehavioral toxicity of carbon nanotubes in mice: focus on brain derived neurotrophic factor messenger RNA and protein. Toxicol Ind Health 2016:1–11.
Kayat J, Gajbhiye V, Tekade RK, Jain NK. Pulmonary toxicity of carbon nanotubes: a systematic report. Nanomedicine. 2011;7:40–9.
Toyokuni S, Jiang L, Kitaura R, Shinohara H. Minimal inflammogenicity of pristine single-wall carbon nanotubes. Nagoya J Med Sci. 2015;77:195–202.
Chen HH, Lucas JA, Chen M. Effect of carbon nanotubes on Chinese hamster ovarian cells. Nanotech. 2011;6:513–6.
Donkor D, Tang XS. Tube length and cell type-dependent cellular responses to ultra-short single-walled carbon nanotube. Biomaterials. 2014;35(9):3121–31.
Iijima S, Yudasaka M, Yamada R, Bandow S, Suenaga K, Kokai F, et al. Nano-aggregates of single-walled graphitic carbon nano-horns. Chem Phys Lett. 1999;309:165–70.
Nakamura M, Tahara Y, Murakami T, Iijima S, Yudasaka M. Gastrointestinal actions of orally-administered single-walled carbon nanohorns. Carbon. N Y. 2014;69:409–16.
Han B, Zhang M, Tang T, Zheng Q, Wang K, Li L, Chen W. The Long-Term Fate and Toxicity of PEG-Modified Single-Walled Carbon Nanotube Isoliquiritigenin Delivery. Journal of nanomaterials 2014. doi.org/10.1155/2014/257391.
Kang S, Pinault M, Pfefferle LD, Elimelech M. Single-walled carbon nanotubes exhibit strong antimicrobial activity. ACS Langmuir. 2007;14:8670–3.
Nagarajan R. ACS symposium series. In Nanomaterials for Biomedicine. Washington, DC: American Chemical Society; 2012.
Yah CS, Simate GS. Nanoparticles as potential new generation broad spectrum antimicrobial agents. J Pharm Sci. 2015;23:43.
Dizaj SM, Mennati A, Jafari S, Khezri K. Adibkia K. Antimicrobial Activity of Carbon-Based Nanoparticles 2015;5(x) doi:105681/apb. 2015:003.
Arias LR, Yang L. Inactivation of bacterial pathogens by carbon nanotubes in suspensions. ACS Langmuir. 2009;22:3003–12.
Pasquini LM, Hashmi SM, Sommer TJ, Elimelech M, Zimmerman JB. Impact of surface functionalization on bacterial cytotoxicity of single-wall carbon nanotubes. Environment Science Technology. 2012;46:6297–305.
Dosunmu E, Chaudhari AA, Singh SR, Dennis VA, Pillai SR. Silver-coated acrbon nanotubes downregulate the expression of Pseudomonas aeruginosa virulence genes: a potential mechanism for their antimicrobial effect. Int J Nanomedicine. 2015;10:5025–34.
Yang C, Mamouni J, Tang Y, Yang L. Antimicrobial activity of single-wall carbon nanotubes: length effect. ACS. Langmuir. 2010;26(20):16013–9.
Le TTA, McEvoy J, Khan E. The effect of single-walled carbon nanotubeson Escherichia coli: multiple indicators of viability. J Nanopart Res. 2015;17(32) https://doi.org/10.1007/s11051-014-2827-y.
Vecitis CD, Zodrow KR, Kang S, Elimelech M. Electronic-structure-dependent bacterial cytotoxicity of single-walled carbon nanotubes. Am Chem Soc. 2010;4(9):5471–9.
Ghafari P, Denis CHS, Power ME, Jin X, Tsou Veronica, Mandal HS, Bols NC, Tang X. Impact of carbon nanotubes on the ingestion and digestion of bacteria by ciliated protozoa. Nat Nanotechnol 2008; 3: 347–351.
Ncibi MC, Sillanpa. Optimized removal of antibiotic drugs from aqueous solutions using single, double and multi-walled carbon nanotubes. J Hazard Mater 2015; 298: 102–110.
Li S, Li H, Wang X, Song Y, Liu Y, Jiang L, et al. Super-hydrophobicity of large-area honeycomb-like aligned carbon nanotubes. J Phys Chem B. 2002;106(36):9274–6.
Yuan WZ, Mao Y, Zhao H, Sun JZ, Xu HP, Jin JK, et al. Electronic interactions and polymer effect in the functionalization and solvation of carbon nanotubes by pyrene- and ferrocene-containing poly ( 1-alkyne ) s. Macromolecules. 2008:701–7.
Duque JG, Cognet L, Parra-vasquez ANG, Nicholas N, Schmidt HK, Pasquali M. Stable luminescence from individual carbon nanotubes in acidic, basic, and biological environments. J Am Chem Soc. 2008;9:2626–33.
Oh H, Sim J, Ju S. Binding affinities and thermodynamics of noncovalent functionalization of carbon nanotubes with surfactants. ACS Langmuir. 2013;29:11154–62.
Karajanagi SS, Yang H, Asuri P, Sellitto E, Dordick JS, Kane RS. Protein-assisted Solubilization of single-walled carbon nanotubes. ACS Langmuir. 2006;25:1392–5.
Mohamed M, Tripathy M, Majeed AA. Studies on the thermodynamics and solute–solvent interaction of polyvinyl pyrrolidone wrapped single walled carbon nanotubes (PVP-SWNTs) in water over temperature range 298.15–313.15K. Arab J Chem. 2013;
Shamsuddin SA, Halim NHA, Deraman N, Hashim U. The characterization study of functionalized multi-wall carbon nanotubes purified by acid oxidation. IEEE Reg Symp Micro Nano Electron. 2011;2011:263–5.
Ziegler KJ, Gu Z, Peng H, Flor EL, Hauge RH, Smalley RE. Controlled oxidative cutting of single-walled carbon nanotubes. J Am Chem Soc. 2005;39(8):1541–7.
Chen J, Liu H, Weimer WA, Halls MD, Waldeck DH, Walker GC. Noncovalent engineering of carbon nanotube surfaces by rigid, functional conjugated polymers. J Am Chem Soc. 2002;124:9034–5.
Buffa F, Hu H, Resasco DE. Side-Wall functionalization of single-walled carbon nanotubes with 4-Hydroxymethylaniline followed by polymerization of ϵ -Caprolactone. Macromolecules. 2005;38:8258–63.
Qin S, Qin D, Ford WT, Resasco DE, Herrera JE. Functionalization of single-walled carbon nanotubes with polystyrene via grafting to and grafting from methods. Macromolecules. 2004;37:752–7.
Qu L, Lin Y, Hill DE, Zhou B, Wang W, Sun X, et al. Polyimide-functionalized carbon nanotubes: synthesis and dispersion in nanocomposite films. Macromolecules. 2004;37:6055–60.
Yuan WZ, Sun JZ, Dong Y, 1ussler MH, Yang F, Xu HP, et al. Wrapping carbon nanotubes in pyrene-containing poly ( phenylacetylene) chains: solubility, stability, light emission, and surface photovoltaic properties. Macromolecules. 2006;39:8011–20.
White B, Banerjee S, O’Brien S, Turro NJ, Herman IP. Zeta-potential measurements of surfactant-wrapped individual single-walled carbon nanotubes. J Phys Chem C. 2007;111(37):13684–90.
Campbell JF, Tessmer I, Thorp HH, Erie DA, Hill C, Carolina N. Atomic force microscopy studies of DNA-wrapped carbon nanotube structure and binding to quantum dots. J Am Chem Soc. 2008;18:10648–55.
Moore VC, Strano MS, Haroz EH, Hauge RH, Smalley RE, Schmidt J, et al. Individually suspended single-walled carbon nanotubes in various surfactants. Nano Lett. 2003;3(10):1379–82.
O'Connel MJ, Bachilo SM, Huffman CB, Moore VC, Strano MS, Haroz EH, et al. Band gap fluorescence from individual single-walled carbon nanotubes. Science. 2002;297:539–96.
Star A, Stoddart JF. Dispersion and solubilization of single-walled carbon nanotubes with a hyperbranched polymer. Macromolecules. 2002;35(19):7516–20.
Fujigaya T, Nakashima N. Non-covalent polymer wrapping of carbon nanotubes and the role of wrapped polymers as functional dispersants. Sci Technol Adv Mater. 2015;16:1–21.
Star A, Stoddart JF, Steuerman D, Diehl M, Boukai A, Wong EW, et al. Preparation and properties of polymer-wrapped single-walled carbon nanotubes. Angew Chem Int Ed. 2001;40(9):1721–5.
O’Connell MJ, Boul P, Ericson LM, Huffman C, Wang YH, Haroz E, et al. Reversible water-solubilization of single-walled carbon nanotubes by polymer wrapping. Chem Phys Lett. 2001;342(3–4):265–71.
Li Z, Guan H, Yu N, Xu Q, Imae I, Wei J. Modification on carbon nanotubes with assistance of supercritical carbon dioxide: chemical interaction, solubility, and light emission. J Phys Chem C. 2010;114:10119–25.
Zhang F, Zhang H, Zhang Z, Chen Z, Xu Q. Modification of carbon nanotubes: water-soluble polymers nanocrystal wrapping to periodic patterning with assistance of supercritical CO2. Macromolecules. 2008;41:4519–23.
Kang YK, Lee O, Deria P, Kim SH, Park TH, Bonnell DA, et al. Helical wrapping of single-walled carbon nanotubes by water soluble poly ( p -phenyleneethynylene ). Am Chem Soc. 2009;9:1414–8.
Caddeo C, Melis C, Colombo L, Mattoni A. Understanding the helical wrapping of poly (3-hexylthiophene) on carbon nanotubes. Society. 2010;114(49):21109–13.
Chung W, Nobusawa K, Kamikubo H, Kataoka M, Fujiki M, Naito M. Time-resolved observation of chiral-index-selective wrapping on single-walled carbon nanotube with non-aromatic polysilane. J Am Chem Soc. 2013;135(6):2374–83.
Deria P, Von Bargen CD, Olivier J-H, Kumbhar AS, Saven JG, Therien MJ. Single-handed helical wrapping of single-walled carbon nanotubes by chiral, ionic, semiconducting polymers. J Am Chem Soc. 2013;135(43):16220–34.
Mao X, Rutledge GC, Hatton TA. Polyvinylferrocene for noncovalent dispersion and redox- controlled precipitation of carbon nanotubes in nonaqueous media. ACS Langmuir. 2013;29:9626–34.
Liu J, Moo-Young J, McInnis M, Pasquinelli M a., Zhai L. Conjugated polymer assemblies on carbon nanotubes. Macromolecules 2014;47(2):705–712.
Liang S, Zhao Y, Adronov A. Selective and reversible noncovalent functionalization of single-walled carbon nanotubes by a pH-responsive vinylogous tetrathiafulvalene-fluorene copolymer. J Am Chem Soc. 2014;136(3):970–7.
Mohamed M, Shah SA, Mohamed R, Majeed ABA, Tripathy MK. Solute solvent interactions of polyvinyl pyrrolidone wrapped single walled carbon nanotubes (PVP-SWNTs) in water by viscometric studies. Orient J Chem. 2013;29(2):539–44.
Mohamed M, Affendi MMMMR, Zulkefeli M, Majeed a B a, Tripathy MK. Solute solvent interactions of polyvinyl pyrrolidone wrapped single walled carbon nanotubes (PVP-SWNTs) in water by acoustic studies. J Nanofluids. 2013;2(2):140–6.
Takahashi O, Kohno Y, Nishio M. Relevance of weak hydrogen bonds in the conformation of organic compounds and bioconjugates: evidence from recent experimental data and high-level ab initio MO calculations. Chem Rev. 2010;110(10):6049−6076.
Moore TL, Pitzer JE, Podila R, Wang X, Lewis RL, Grimes SW, et al. Multifunctional polymer-coated carbon nanotubes for safe drug delivery. Materials views. 2013;30:365–73.
Koh B, Kim G, Yoon HK, Park JB, Kopelman R. Fluorophore and dye-assisted dispersion of carbon nanotubes in aqueous solution. ACS Langmuir. 2012;28:11676–86.
Chen J, Chen S, Zhao X, Kuznetsova LV, Wong SS, Ojima I. Functionalized single-walled carbon nanotubes as rationally designed vehicles for tumor-targeted drug delivery. J Am Chem Soc. 2008;19:16778–85.
Kosuge H, Sherlock SP, Kitagawa T, Dash R, Robinson JT, Dai H, et al. Near infrared imaging and photothermal ablation of vascular inflammation using single-walled carbon nanotubes. J Am Heart Assoc. 2012;1(6):e002568.
Huang X, El-sayed IH, Qian W, El-sayed MA. Cancer cell imaging and Photothermal therapy in the near-infrared region by using gold Nanorods. J Am Chem Soc. 2006;3:2115–20.
Focke PJ, Wang X, Larsson HP. Neurotransmitter transporters: structure meets function. Structure. 2013;21(5):694–705.
Kruss S, Landry MP, Vander EE, Lima BMA, Reuel NF, Zhang J, et al. Neurotransmitter detection using corona phase molecular recognition on fluorescent single-walled carbon nanotube sensors. J Am Chem Soc. 2014;136:713−724.
Son SJ, Bai X, Lee SB. Inorganic hollow nanoparticles and nanotubes in nanomedicine part 2 : imaging, diagnostic, and therapeutic applications. Drug Discov Today. 2007;12(August):657–63.
Hashida Y, Tanaka H, Zhou S, Kawakami S, Yamashita F, Murakami T, et al. Photothermal ablation of tumor cells using a single-walled carbon nanotube-peptide composite. J Control Release. 2014;173:59–66.
Moon HK, Lee SH, Choi HC. In vivo near-infrared mediated tumor destruction by photothermal effect of carbon nanotubes. ACS Nano. 2009;3(11):3707–13.
Acknowledgments
The authors would like to acknowledge the Ministry of Higher Education (MOHE) Malaysia for Fundamental Research Grant Scheme (600-RMIA/FRGS 5/3 (4/2014)) and Universiti Teknologi MARA for providing support.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Rights and permissions
About this article
Cite this article
Chik, M.W., Hussain, Z., Zulkefeli, M. et al. Polymer-wrapped single-walled carbon nanotubes: a transformation toward better applications in healthcare. Drug Deliv. and Transl. Res. 9, 578–594 (2019). https://doi.org/10.1007/s13346-018-0505-9
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13346-018-0505-9