Introduction

Mosquitoes (Diptera: Culicidae) represent a key threat for lives and livelihoods of millions of people worldwide, since over 1 million people worldwide die from mosquito-borne diseases every year (Jensen and Mehlhorn 2009; Raghavendra et al. 2011; WHO 2013). Culicidae act as vectors for devastating pathogens, such as malaria, yellow fever, dengue, and West Nile (Benedict et al. 2007; Paupy et al. 2009). The mosquito, Anopheles stephensi, is one of the most important malaria vectors in India and other West Asian countries (Burfield and Reekie 2005; Mittal et al. 2005). Malaria is a mosquito-borne disease caused by pathogens of the genus Plasmodium. Nearly three billion people are at risk of malaria worldwide (Guerra 2006). Human malaria cases are usually due to five Plasmodium sp., namely Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale, and Plasmodium knowlesi (Duval 2009). P. falciparum is usually considered the most lethal. In the sub-Saharan Africa, approximately 25 million pregnant women are at risk of infection by P. falciparum every year. P. falciparum infection can cause severe maternal anemia, low birth weight, and prenatal mortality. Furthermore, only for African countries, low birth weight associated with malaria during pregnancy is estimated to result in 100,000 infant deaths each year (Desai et al. 2007; Sharma et al. 2010; see Raghavendra et al. 2011 for a recent review).

In this scenario, vector control is a crucial prevention tool against mosquito-borne diseases. Mosquito larvae are usually targeted using organophosphates and insect growth regulators, and indoors residual spraying and insecticide-treated bed nets are also employed for reducing transmission of malaria in tropical countries (Lees et al. 2014; see also Benelli 2015). However, these chemicals have negative effects on human health and/or the environment and lead to resistance in mosquito populations (Hemingway and Ranson 2000; Lees et al. 2014). Recently, renewed interest has been recently devoted to the potential of sterile insect technique (SIT) for suppression of mosquito vectors, with a special focus to the genus Anopheles (Lees et al. 2014; Oliva et al. 2014). Biological control of mosquito vectors using predatory copepods also received attention (Murugan et al. 2011). In latest years, huge efforts have been carried out to investigate the insecticidal activity of eco-friendly compounds extracted by plants, and a number of new chemicals have been proposed as effective toxics and/or repellents, even at low dosages (e.g., Amer and Mehlhorn 2006a, b; Benelli et al. 2013a, b, 2014, 2015a, b, c; Conti et al. 2014).

Besides mosquito-borne diseases, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. About 1.6 million people die every year due to diarrheal diseases, with special reference to cholera, attributable to lack of access to safe drinking water; about 90 % are children (<5 years) (Swanner and Meunier 2014). Intestinal helminthes are also plaguing a number of developing countries due to contaminated drinking water, with 133 million suffering of high intensity intestinal helminthes infections and 1.5 million cases of clinical hepatitis per year. More than 80 million people have an active infection by Trachoma (also known as granular conjunctivitis or Egyptian ophthalmia, caused by the bacterium Chlamydia trachomatis), and approximately 500 million people are at risk of trachoma (Swanner and Meunier 2014). Hygienic water treatments usually rely to the addition of chemical coagulants, such as aluminum sulfate, and chlorine as a bactericide. The availability of these chemicals in poorly developed countries depends on foreign exchange and thus is unreliable and unpredictable. However, plant parts and extracts have been used for many centuries as coagulants to clarify turbid waters in rural areas of the world (Schulz and Okun 1984; Jahn 1988). Nowadays, we believe that plant-borne compounds could be a low-cost and eco-friendly alternative for water purification, in alternative to conventional chemical treatments.

The use of plant-borne chemicals for the “green synthesis” of nanoparticles is a low-cost, single-step, and eco-friendly (Huang et al. 2007). The green synthesis of nanoparticles is advantageous over other chemical and physical methods, since it is not necessary to use high pressure, high energy, high temperature, or toxic chemicals (Goodsell 2004; Muthukumaran et al. 2015). In addition, the use of plant extracts for the synthesis of nanoparticles can be advantageous over other environmentally benign biological processes since it eliminates elaborate procedures maintaining cell cultures. Recently, several plant species have been successfully employed for rapid extracellular synthesis of silver, copper, and gold nanoparticles (Shankar et al. 2004; Kumar and Yadav 2009; Song and Kim 2009). Biosynthesized silver nanoparticles have been used in label-free colorimetric assay to detect enzymatic reactions (e.g., Wei et al. 2008), surface plasmon resonance studies (e.g., Turney et al. 2004; Kundu et al. 2004), antimicrobial materials (e.g., Duran et al. 2005), antiviral studies (e.g., Elechiguerra et al. 2005), and as mosquitocidals (e.g., Naresh Kumar et al. 2011; Rajkumar and Rahuman 2011; Muthukumaran et al. 2015; Suresh et al. 2015).

The genus Aloe (Asphodelaceae) comprises more than 500 species, but only few of them are of medical importance (Deng et al. 1999). Among them, Aloe vera is the most interesting species. Its leaves contain over 200 bioactive constituents, including aminoacids, anthraquinones, enzymes, minerals, vitamins, lignins, monosaccharides, polysaccharides, salicylic acid, saponins, and sterols (e.g., Waller et al. 1978; Urch 1999; Rajasekaran et al. 2005). A. vera is a plant containing a huge number of anti-oxidants (e.g., vitamins A, C, E), as well as saponins, that are responsible of strong anti-microbial properties against bacteria, viruses, fungi, and yeasts (Reynolds and Dweck 1999; Lee et al. 2001).

In this research, we investigated the mosquitocidal and antibacterial properties of A. vera leaf extract and silver nanoparticles synthesized from silver nitrate using a cell-free aqueous leaf extract of A. vera (Chandran et al. 2006). The synthesized silver nanoparticles were characterized by UV–vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Mosquitocidal properties were assessed in laboratory against larvae (I–IV instar) and pupae of the malaria vector An. stephensi. Green-synthesized silver nanoparticles were also tested for their mosquitocidal properties in the field. Antibacterial properties of nanoparticles were evaluated against Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi using the agar disk diffusion and minimum inhibitory concentration protocol. We also focused on the efficiency of micro-emulsions prepared using A. vera extract and silver nanoparticles in water treatment. Water quality parameters, such as color, turbidity, and pH, were analyzed over the different breeding sites of mosquitoes in pretreatment and post-treatment phases.

Materials and methods

An. stephensi rearing

Eggs of An. stephensi were collected from local breeding habitats at the National Institute of Communicable Disease Centre (Coimbatore, India) using an “O”-type brush. Eggs were transferred to laboratory conditions [27 ± 2 °C, 75–85 % R.H., 14:10 (L/D) photoperiod] and placed in 18 × 13 × 4-cm plastic containers containing 500 mL of tap water, waiting for larval hatching. An. stephensi larvae were reared in the plastic containers described above and fed daily with a mixture of crushed dog biscuits and hydrolyzed yeast at 3:1 ratio (w/w). Water was renewed each 2 days. The breeding medium was checked daily and dead individuals were removed. Breeding containers were kept closed with muslin cloth to prevent contamination by foreign mosquitoes. Pupae were collected daily from culture containers and transferred to glass beakers containing 500 mL of water. Each glass beaker contained about 50 mosquito pupae and was placed in a mosquito cage (90 × 90 × 90 cm) for adult emergence. Plastic frames and chiffon walls composed each cage. Freshly emerged adults were maintained in laboratory conditions. Adults were fed with a sugar solution (10 %, w/v) for 3 days, and then females were fed on human arms of healthy volunteers every 2 days at 18:00 hours (Judson 1967). Both sexes were continuously provided with 10 % (w/v) glucose solution as described by Villani et al. (1983) on cotton wicks. The cotton was always kept moist with the solution and changed every day. To collect eggs, an egg trap lined with filter paper containing pure water was always placed close to the right corner of the cage.

Aloe vera plants and extracts

A. vera plants were collected from the garden of Bharathiar University (Coimbatore, India). Plants were identified at the Botanical Survey of India, and voucher specimens were deposited at the Zoology Department of Bharathiar University (Coimbatore, India). A. vera leaves were transferred to laboratory conditions, washed with tap water, shade dried at room temperature, and powdered using an electrical grinder. Then, 500 g of plant material was extracted using 1.5 L of ethanol for 72 h, and the crude plant extract was concentrated on a rotary evaporator and stored at 4 °C. One gram of the plant residue was dissolved in 100 mL of acetone, as 1 % (w/v) stock solution.

Green synthesis and characterization of silver nanoparticles

The A. vera leaf extract was prepared adding 10 g of washed and finely cut leaves in a 300-mL Erlenmeyer flask filled with 100 mL of sterilized double distilled water and then boiling the mixture for 5 min, before finally decanting it. The extract was filtered using Whatman filter paper No. 1, stored at −15 °C and tested within 5 days. The filtrate was treated with aqueous 1-mM AgNO3 solution in an Erlenmeyer flask and incubated at room temperature. A brown-yellow solution indicated the formation of silver nanoparticles, since aqueous silver ions were reduced by the A. vera extract generating stable silver nanoparticles in water. Silver nitrate was purchased from the Precision Scientific Co. (Coimbatore, India).

The presence of green-synthesized silver nanoparticles was confirmed by sampling the reaction mixture at regular intervals, and the absorption maxima was scanned by UV–Vis, at the wavelength of 200–700 nm in a UV-3600 Shimadzu spectrophotometer at 1-nm resolution. Furthermore, the reaction mixture was subjected to centrifugation at 15,000 rpm for 20 min, and the resulting pellet was dissolved in de-ionized water and filtered through a Millipore filter (0.45 μm). An aliquot of this filtrate containing silver nanoparticles was used for scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) analyses.

The structure and composition of freeze-dried purified silver particles were analyzed by using a 10-kV ultrahigh-resolution scanning electron microscope; 25 μL of sample was sputter-coated on a copper stub, and the morphology of nanoparticles was investigated using a FEI QUANTA-200 SEM. Surface groups of the nanoparticles were qualitatively confirmed by using FTIR spectroscopy (Stuart 2002), with spectra recorded by a PerkinElmer Spectrum 2000 FTIR spectrophotometer. In addition, EDS analyzed the presence of metals in the sample.

Mosquitocidal tests against An. stephensi in laboratory conditions

Following the methods reported in Benelli et al. (2013a, b, 2015a, b), 25 An. stephensi larvae (I, II, III, or IV instar) or pupae were placed in 500-mL beakers and exposed for 24 h to dosages of 20, 40, 60, 80 and 100 ppm (A. vera extract) and 2, 4, 8, 16 and 32 ppm (A. vera-synthesized silver nanoparticles). A 0.5-mg larval food was provided for each test concentration. Each concentration was replicated three times against all instars. Control mosquitoes were exposed for 24 h to the corresponding concentration of the solvent (A. vera extract) or dechlorinated water (A. vera-synthesized silver nanoparticles). dechlorinated water. Percentage mortality was calculated as follows: percentage mortality = (number of dead individuals / number of treated individuals) * 100.

Mosquitocidal tests against An. stephensi in field conditions

A. vera-synthesized silver nanoparticles were applied in six external water reservoirs at the National Institute of Communicable Disease Centre (Coimbatore, India), using a knapsack sprayer (Private Limited 2008, Ignition Products, India). Pretreatment and post-treatment at 24, 48, 72, and 96 h were conducted using a larval dipper. Toxicity was assessed against third- and fourth-instar larvae. Larvae were counted and identified to specific level. More than 98 % of all surveyed larvae belong to An. stephensi. Six trials were conducted for each test site with similar weather conditions (27 ± 2 °C; 79 % R.H.). The required quantity of mosquitocidal was calculated on the basis of the total surface area and volume (0.25 m3 and 250 L); the required concentration was prepared using 10× the observed laboratory LC50 values (Murugan et al. 2003; Suresh et al. 2015). Percentage reduction of the larval density was calculated using the formula: percentage reduction = (C − T) / C × 100, where C is the total number of mosquitoes in the control and T is the total number of mosquitoes in the treatment. Water quality parameters are as follows: Color, turbidity, and pH were measured following the methods of the American Public Health Association (2005).

Preparation of treatment coagulants followed methods reported by Schwarz (2000). Leaves of A. vera were shade-dried, powdered using an electric grinder, and mixed with a small amount of clean water to form a paste. The paste was diluted to obtain the following raw water turbidity: >50, 50–150, and >150 mg/L. The final concentration was 50, 30–100, and >150 mg/L, respectively (Schwarz 2000). After filtering insoluble material with a fine-mesh muslin cloth, the coagulant was added and quickly mixed for 30 s. Then, the preparation was covered for at least 1 h without disturbance.

Toxicity of Aloe vera extracts and green synthesized nanoparticles against bacteria

The bacteria species used in this study were purchased from Microbial Type Culture Collection and Gene Bank Institute of Microbial Technology Sector 39-A, Chandigarh-160036 (India). Tested bacteria were B. subtilis, K. pneumoniae, and S. typhi. Eighteen- to 24-h-old bacterial cultures were used for preparation of the testing cultures. Nutrient broth composition was peptone (5 g/L), hydrolyzed yeast extract (1.50 g/L), beef extract (1.50 g/L), and sodium chloride (5 g/L). Final pH was 7.4. Thirteen grams of nutrient broth was suspended into 100 mL of distilled water. Twenty-five milliliters of the nutrient broth was transferred each into four conical glass flasks, and they were autoclaved at 1210 c for 15 min at 15 psi. After autoclaving the test tubes, each tested species was inoculated and incubated at 37 °C for 24 h. After 24 h, the culture attained 2 × 10−6 cfu/mL, which was further used for antibacterial assay. Antibacterial activity of green synthetized nanoparticles and A. vera extracts was assessed using the agar disk diffusion method (Clinical and Laboratory Standards Institute 2006). The tested bacteria were swabbed on the Muller Hinton agar medium plates. Three disks were inserted in each plate, treated with three different concentrations of the tested compounds. Then, plates were incubated at 37 °C for 24 h. After the incubation, the zones of inhibition (mm) were measured using a photomicroscope (Leica ES2, Germany).

Data analysis

Mosquito toxicity and bacteria inhibition growth data were transformed into arcsine/proportion values and then analyzed using a two-way ANOVA with two factors (i.e., the dosage and the mosquito instar or the bacterium species). Means were separated using Tukey’s HSD test. P < 0.05 was used for the significance of differences between means. Mosquito mortality data were analyzed by probit analysis, calculating LC50 and LC90 following the method by Finney (1971). Water quality data before and after the treatment with mosquitocidals were analyzed using one-way ANOVA (P < 0.05). All the analyses were performed using JMP 7 SAS.

Results and discussion

Characterization of green-synthesized silver nanoparticles

Green-synthesized silver nanoparticles were characterized by UV–vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The UV–vis spectrum of A. vera leaf extract as function of reaction time is reported in Fig. 1. The color intensity of the leaf extracts of the extract incubated with Ag+ ions at the beginning of reaction and after 120 min of reaction is given in Fig. 1a, b, respectively. Maximum absorption was at 410 nm (Fig. 1c). The color change was attributed to the excitation of surface plasmon resonance (SPR) in metal nanoparticles (Natarajan et al. 2010). Reduction of Ag+ ions present in the aqueous solution of silver complex during the reaction with the constituents from A. vera leaf extract observed by the UV–vis spectroscopy revealed that the presence of silver nanoparticles was correlated with variations in the UV-vis spectrum. Metal silver nanoparticles have free electrons, which give rise to an SPR absorption band, due to the combined vibration of electrons of metal nanoparticles in resonance with the light wave (Noginov et al. 2006). Silver nanoparticles were observed as stable in solution and showed little aggregation. The plasmon bands were broadened with an absorption tail in longer wavelengths, and this could be related to the size distribution of nanoparticles (Ahmad et al. 2003). SEM micrographs (Fig. 2) of A. vera-synthesized nanoparticles showed almost spherical and cubic structures with a size range of 35–55 nm (see also Chandran et al. 2006). Similarly, silver nanoparticles synthesized using leaf extract of Acalypha indica showed an average size of 20–30 nm (Krishnaraj et al. 2010). As a general trend, the shape of plant-mediated silver nanoparticles has been described as spherical, with the exception of those synthesized using neem plant material, which leads to nanoparticles with spherical or flat morphology (size 5–35 nm) (Shankar et al. 2004).

Fig. 1
figure 1

Chromatic variation of tested compounds a before and b after the process of reduction of Ag+ to Ag nanoparticles. c UV visualization of the absorption spectrum of silver nanoparticles synthesized using Aloe vera leaf extract at three-time intervals

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Fig. 2
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Scanning electron micrographs of silver nanoparticles synthesized using Aloe vera leaf extract: a medium magnification (×10,000) and b high magnification (×20,000)

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Figure 3 shows a standard energy-dispersive X-ray (EDX) spectrum recorded on the examined SEM samples. In the middle part of the spectrum, two peaks were located between 2 and 4 kV, where silver is present. Both were related to the silver characteristic lines K and L. Quantitative analysis showed high oxygen content (63.34 %) in the examined samples. Silver content was about 20.85 %. The FTIR spectra of A. vera-synthesized silver nanoparticles showed transmittance peaks at amines group region (Fig. 4). These peaks indicate that a carbonyl group formed amino acid residues and that these residues capped silver nanoparticles to prevent agglomeration, thus stabilizing the medium (Sathyavathi et al. 2010). Our peaks at 1620–1636 cm−1 could represent carbonyl groups from polyphenols such as catechin gallate, epicatechin gallate, epigallocatechin, epigallocatechin gallate, gallocatechin gallate, and theaflavin. Overall, our results suggest that molecules attached with silver nanoparticles had free and bound amide groups. These amide groups may also be linked to the aromatic rings. We hypothesize that the compounds found with silver nanoparticles may belong to polyphenols with an aromatic ring and bound amide region (see also Kumar et al. 2010). The peak at 1381 cm−1 corresponds to the C–N stretching of the aromatic amine group (Mahitha et al. 2011). In addition, results of the FTIR values of A. vera-synthesized silver nanoparticles showed the presence of different functional groups such as alkane groups, methylene groups, alkene groups, amine groups, and carboxylic acids, and these functional groups have been previously highlighted for their potential as reducing agents in the synthesis of metal nanoparticles (Cho et al. 2005).

Fig. 3
figure 3

Energy-dispersive X-ray spectrum (EDX) of silver nanoparticles synthesized using the Aloe vera leaf extract

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Fig. 4
figure 4

Fourier transform infrared (FTIR) spectrum of silver nanoparticles synthesized using the Aloe vera leaf extract.

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Post-treatment water quality

Posttreatment water quality was evaluated analyzing watercolor, turbidity, and pH (Table 1). Watercolor, turbidity, and pH were significantly reduced after treatment with both A. vera extract and A. vera-synthesized silver nanoparticles (Table 1).

Table 1 Quality parameters of the mosquito breeding water before and after the treatment with Aloe vera extract and A.vera-synthesized silver nanoparticles
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Laboratory and field mosquitocidal assays against An. stephensi

In laboratory conditions, the A. vera extract was toxic against An. stephensi larvae and pupae, even at low dosages (Fig. 5a). A dose-dependent effect was found (F = 4.559, d.f. = 4; P < 0.01), as previously highlighted for other plant-borne mosquitocidals (Panneerselvam et al. 2012; Benelli et al. 2013a, 2015a, b). In our experiments, LC50 were 48.79 ppm (I instar), 59.09 ppm (II instar), 70.88 ppm (III instar), 83.58 ppm (IV instar), and 152.55 ppm (pupae) (Table 2).

Fig. 5
figure 5

Toxicity of a Aloe vera extract and b A. vera-synthesized silver nanoparticles, against the malaria vector Anopheles stephensi. T-bars represent standard deviations. Values are mean ± standard deviation of three replicates. Different letters above each column indicated significant differences among treatments (two-way ANOVA, Tukey’s HSD test, P < 0.05)

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Table 2 Larval and pupal toxicity of the Aloe vera extract against the malaria vector Anopheles stephensi
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In laboratory experiments, the A. vera-synthesized silver nanoparticles were highly toxic against An. stephensi (Fig. 5b). LC50 were 3.825 ppm (I instar), 4.119 ppm (II instar), 4.982 ppm (III instar), 5.711 ppm (IV instar), and 6.113 ppm (pupae) (Table 3). In field assays, the larval density of An. stephensi was 51.00 ± 8.25 mosquitoes (mean ± SD) before treatment. After the application of silver nanoparticles (10 × LC50), the larval density was 13 ± 7.3 after 24 h, 6.83 ± 6.3 after 48 h, and 1.1 ± 1.8 after 72 h. Overall, the silver nanoparticle treatment achieved an An. stephensi larval reduction of 74.5, 86.6, and 97.7 %, after 24, 48, and 72 h, respectively. Comparable toxicity rates have been recently reported for silver nanoparticles synthesized using Chomelia asiatica against An. stephensi larvae (LC50 = 17.95 ppm) (Muthukumaran et al. 2015). Priyadarshini et al. (2012) reported that silver nanoparticles synthesized using Euphorbia hirta leaf extract were toxic against An. stephensi larvae (I–IV instar), with LC50 values ranging from about 10 to 28 ppm. Green-synthesized silver nanoparticles using Mimosa pudica leaves showed LC50 values of about 10 ppm against larvae of Anopheles subpictus and Culex quinquefasciatus (Marimuthu et al. 2011). The toxicity of silver nanoparticles against An. stephensi larvae may be due to the small size of nanoparticles, which penetrate into the cells where they interfere with molting and other physiological processes (Sap-Iam et al. 2010; Naresh Kumar et al. 2011). In addition, green-synthesized silver nanoparticles have been studied also for their anti-plasmodial potential, a recent example is the plasmodial inhibitory effect of Andrographis paniculata-synthesized silver nanoparticles, and it was about 26 % when tested at 25 μg/mL and 83 ± 0.5 % at 100 μg/mL (Panneerselvam et al. 2011). Also, fungi-mediated synthesis has been reported as a good method to produce mosquitocidal nanoparticles. For instance, Soni and Prakash (2012) reported that the Chrysosporium tropicum-mediated synthesis of silver nanoparticles was effective against third instar larvae of Aedes aegypti (LC50 = about 4 ppm). Similarly, silver nanoparticles synthesized using the filamentous fungus Cochliobolus lunatus were also highly toxic against second, third, and fourth instar larvae of A. aegypti (LC50 = 1.29, 1.48, and 1.58 ppm) and An. stephensi (LC50 = 1.17, 1.30, and 1.41 ppm) (Salunkhe et al. 2011).

Table 3 Larval and pupal toxicity of silver nanoparticles synthesized using Aloe vera extract against the malaria vector Anopheles stephensi
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Antibacterial properties

Silver nanoparticles synthesized using A. vera plant extract showed antibacterial properties against B. subtilis, K. pneumoniae, and S. typhi (Table 4). A dose-dependent effect was found (F = 3.223; d.f. = 3; P < 0.01). At the maximum concentration tested (150 mg/L), they showed strong inhibitory action against B. subtilis (zone of inhibition 80 mm), K. pneumoniae (zone of inhibition 90 mm), and S. typhi (zone of inhibition 90 mm) (Table 4). Aqueous silver ions exposed to bacterial organisms were reduced in solution, leading to the formation of silver hydrosol. The bacterial biomass was pale yellow before the addition of silver ions, and then changed to light and dark brown, evidencing the formation of silver nanoparticles (Table 5). Silver nanoparticle-induced bacterial inhibition has been observed both in Gram-positive and Gram-negative bacteria (e.g., B. licheniformis, see Sereemaspun et al. 2008 and references therein). However, the exact mechanism of the inhibition is still unknown. It has been formulated that the inhibition is due to ionic binding of the silver nanoparticles on the surface of the bacteria, which creates a great intensity of the proton motive force. Also, the silver nanoparticles could invade bacterial cells and bind to the vital enzymes containing thiol groups (Sereemaspun et al. 2008).

Table 4 Inhibition zone induced by Aloe vera-synthesized silver nanoparticles against three bacteria pathogens
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Table 5 Chromatic variation in bacterial cultures after treatment with 1 mM of silver nitrate
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Conclusions

Overall, this research highlights the effectiveness of A. vera extracts as a reducing agent to mediate the green synthesis of silver nanoparticles acting as excellent mosquitocidal and antibacterial tools. The A. vera-induced biological reduction of silver in water would be a boon in the development of clean, nontoxic, and environmentally acceptable production of metal nanoparticles for biological purposes. Indeed, these silver nanoparticles are hydrophilic in nature, able to disperse uniformly in water, stable over time, and highly effective as toxic against the malaria vector An. stephensi at low doses.