Introduction

Nanotechnology, which involves materials being manipulated at the nanoscale, is a key enabling technologies in the twenty-first century (Bayda et al. 2019). Nanotechnology has grown tremendously leading to introduction of many nanomaterials for applications in various fields such as drug delivery, diagnostics, catalysis, environmental remediation, and biomedical field (Kanaoujiya et al. 2023). A lot has been invested in nanotechnology to drive it forward for continuous harnessing of economic and societal benefits. However, despite the numerous benefits of nanotechnology, production of nanomaterials mainly makes use of unsustainable processes such as chemical methods and physical methods that have destructive consequences on the environment. Physical and chemical methods are frequently used in nanomaterials and nanotools synthesis with higher rates of production and homogeneity (Jain et al. 2023). Physical methods include, inter alia, thermal decomposition, mechanical/ball milling and lithography. Chemical methods include; chemical reduction method, chemical vapor deposition, micro-emulsion/colloidal, pyrolysis, sonochemical, photochemical, electrochemical, sol–gel and hydrothermal methods (Chouke et al. 2022).

Materials scientists have made significant developments in the improvement of these methods. However, despite the improvements, these methods are known to consume higher amount of energy, use hazardous solvents and materials in synthesis, and generate large amounts of waste that pose negative impact on environment and humans thus rendering them destructive and unsustainable (Dehno Khalaji 2020). Reports indicate that manufacture of materials is lengthy involving use of hazardous chemicals and generation of significant waste such as contaminated solvents (Jiménez-González et al. 2004). For instance, dispersants, surfactants, or chelating agents are used in chemically synthesized nanomaterials to inhibit particle agglomeration. When used in large scale production, these reagents can be environmental pollutants. Additionally, nanomaterials from these methods may be associated with instability, bio-incompatibility, and toxicity hindering their application in the environment and human beings (Ijaz et al. 2020).

Traditional synthesis of metal nanoparticles normally use hazardous chemicals, generate significant waste and pollutants that adversely affect the environment and consume high energy (Idris and Roy 2023), making such processes to go against the spirit of the sustainable development goals (SDGs) targets 3.9, 6.3, 9.4, 12.4, and 12.5. SDG targets 3.9, 6.3, 9.4, 12.4, and 12.5 seek to achieve sound management, minimization or elimination of use of hazardous chemicals and reduction in generation of waste and pollutants (Katila et al. 2019). These suggest that minimization or eliminating the use of hazardous chemicals and reducing waste generation through green nanotechnology promotes the above-mentioned SDG targets. Additionally, SDG target 9.4 seeks to design resource-use efficient and clean processes to achieve sustainable consumption, decrease carbon footprint and reduce pollution (Katila et al. 2019).

The limitations associated with physical and chemical synthesis remain a big concern that has inspired the search for alternative sustainable synthesis methods such as green nanotechnology that align with the objectives of the aforementioned SDGs targets. Green nanotechnology, which uses eco-friendly technologies to create nanoparticles, is promising and provides impeccable solutions that support sustainable nanotechnology. By using less toxic reagents, utilizing low temperatures, and utilizing renewable energy sources whenever feasible, green synthesis expands on the twelve (12) principles of green chemistry to create nanomaterials. Thus, green synthesis is safer and eco-friendly than conventional methods (Ijaz et al. 2020). Thanks to its easy scale-up, economic viability, environmental friendliness, and simple process, the eco-friendly synthesis of nanomaterials is expanding quickly. There is also research being done on the potential for solvent-free biosynthesis of nanomaterials, albeit the research is still in its early stages, in an effort to support the principles green chemistry (Ahmed et al. 2022).

As a subset of green nanotechnology, biogenic synthesis uses biological sources—plants and microorganisms—as bioreducing, stabilizing, and capping agents (Mughal et al. 2021). Biogenic metal nanoparticle synthesis utilizes green solvents, optimizes atom economy reducing waste generation and proceeds under milder conditions room temperature thus decreasing energy consumption (Kurhade et al. 2021). Moreover, utilization of renewable and biodegradable materials such plant components promotes sustainability. The use of biogenic synthesis not only addresses the limitations of physical and chemical methods but also provides alternative sustainable and scalable processes for application in various sectors (Kisimba et al. 2023). By using biogenic synthesis to achieve sustainability, products and nanomaterials can be produced that support both the current and future generations without endangering human health and the environment (Palit and Hussain 2020). Green nanotechnology can support realization of the SDGs targets by promoting sustainable nanotechnology practices that lessen negative effects on the environment, enhance conservation efforts, and safeguard human health and resources (Aithal and Aithal 2021). Thus, strategies such as this that promote sustainable development goals are highly needed in the field of nanotechnology.

Several reviews have explored the biogenic synthesis of metal nanoparticles (Bhati 2023; Madani et al. 2022; Mughal et al. 2021; Patil and Chandrasekaran 2020; Sharma et al. 2019; Solgi and Taghizadeh 2020). Most of these reviews have focused on the procedures and biological sources used during biogenic synthesis. Despite the clarion call to document interventions that promote sustainable nanotechnology and SDGs targets, reviews that specifically cover and link the potential of biogenic synthesis to address the aforementioned SDGs targets are currently not available in literature and this review aims to fill this gap.

To address this gap, this review is not intended just to summarize biogenic synthesis of metal nanoparticles but rather its novelty lies in linking the potential of biogenic synthesis of metal nanoparticles to addressing SDG targets 3.9, 6.3, 9.4, 12.4, and 12.5. Sustainable nanotechnology themes inter alia eco-friendliness, green energy-efficient processes, green solvent, and biocompatibility that form the basis for biogenic synthesis have been discussed. Studies under each theme have been grouped and discussed with an emphasis on sustainable nanotechnology. Finally, the perspectives and recommendations on biogenic synthesis have been spelled out.

SDGs and green nanotechnology

SDGs targets 3.9. 6.3, 9.4, 12.4 and 12.5 interconnection with green nanotechnology

The pressing political, economic, and environmental problems that the society is currently facing led to the creation of the SDGs (Fallah Shayan et al. 2022). For instance, a report by GlaxoSmithKline (GSK) from a study on waste produced during production of active pharmaceutical ingredients indicated that more than 80% of their waste was solvent related (Jiménez-González et al. 2004). In another study, Dehno Khalaji (2020) indicated that use of physical methods such as thermal decomposition in production of metal nanoparticles consumed high energy (600 °C for 3 h) and generated substantial waste that caused environmental pollution making the process unsustainable. Further, a study by Sarkhosh et al. (2022) demonstrated that zinc oxide nanoparticles synthesized using chemical method detrimentally affected seed germination of Camelina sativa and Brassica napus in a dose-dependent manner.

On this basis, SDGs targets 12.4, 12.5, 3.9 and 6.3 aim to achieve sound management, minimization or elimination of use of hazardous chemicals and reduction in generation of waste and pollutants. In particular, SDG 12 target 4 talks about sound management of chemicals and generated waste throughout their life cycle. Further, the SDG 12.4 targets to significantly reduce release of chemicals and waste into environment to minimize their negative impacts on humans and the environment. SDG 12.5 targets to prevent, reduce, recycle and reuse waste to substantially decrease its generation. SDG 3 target 9 talks about reducing number of deaths and illness from hazardous chemicals, pollutants and contaminants. It is closely related to SDG 6 target 3 talks about reducing pollution and minimizing release of hazardous chemicals and pollutants into water environment to improve water quality (Katila et al. 2019). Biogenic synthesis of metal nanoparticles aims to reduce or entirely eliminate the use of hazardous chemicals and minimize or possibly eliminate generation of pollutants. By use of eco-friendly solvents, maximization of atomy economy to minimize waste generation and elimination of hazardous chemicals and waste to minimize impact on environment and human health, green synthesis substantially contributes to achieving the above-mentioned SDGs targets.

SDG 9 target 4 talks about designing sustainable and resource-use efficient industries, and adoption of clean technologies and processes (Katila et al. 2019). In context, biogenic synthesis aims to optimize resource use, use renewable and biocompatible materials, allow reactions to proceed at room temperature/milder conditions and use energy-efficient processes making the overall production process sustainable. Additionally, green synthesis optimizes atom economy reducing waste generation. Compared to high-energy consuming physical process such as pyrolysis, green synthesis occurs at milder conditions or ambient temperature thereby advancing sustainable consumption (Gupta et al. 2023). By adopting green synthesis, industries will decrease carbon footprint and reduce pollution as envisaged in SDG 9.4.

Implementation green nanotechnology by growing industries to attain SDGs targets

Growing industries are urged to embrace green nanotechnology to enable realization of SDGs targets to foster a sustainable future. The SDGs provides a framework that can adopted by growing industries to achieve sustainable processes. Some key guidelines for adopting green nanotechnology and foster SDGs implementation include: Growing industries embedding sustainability in their operations; Partnering with relevant stakeholders in the implementation process; Setting measurable SDGs targets and tracking their progress; and investing in research and development for sustainable processes, new clean technologies and approaches to overcome implementation barriers (Aithal and Aithal 2021).

By aligning and integrating their operations with eco-friendly nanotechnology solutions, these industries can progress toward SDGs targets 3.9, 6.3, 9.4, 12.4 and 12.5. For instance, Pfizer pharmaceutical industry successfully integrated green chemistry in its production of celecoxib. Pfizer’s celecoxib synthesis based on green chemistry principles used benign solvents (50% aqueous isopropanol and methanol) eliminating the hazardous hexane and methylene chloride, and substantially decreased the use of hazardous hydrazine. The yield went up from 63 to 84% and waste generation went down by 35% thus reducing environment impact (Saxena et al. 2022). In this case, the shift toward green and sustainable strategies for drug synthesis through judicious selection of greener solvents contributes to eco-friendly drug production and aligns with SDGs’ objectives of responsible consumption and production.

Several case studies and pilot projects have demonstrated the practical implementation of biogenic nanoparticles in sustainable technologies. For example, metal nanoparticles biogenically synthesized have been used in environmental bioremediation, effectively removing pollutants and waste (Bhardwaj et al. 2023). Use of biogenic metal nanosorbents in treatment of wastewater demonstrates practical application of biogenic nanoparticles in a sustainable manner. For instance, silver nanoparticles synthesized using P. thonningii leaf extract have been successfully utilized in removal of heavy metals from wastewater (Tailor et al. 2020). Goutam and co-workers produced titanium dioxide nanoparticles by use of Jatropha curcas leaf extract and applied the biogenic nanoparticles to remove 74.5% chromium and 82.3% chemical oxygen in wastewater (Goutam et al. 2018). In the pharmaceutical field, green synthesized platinum nanoparticles exhibited activity against P. aeruginosa and S. pyogenes and anticancer activity on SKO-3 and SK-GT-4 cell lines (Ali and Mohammed 2021).

A comparative study by Sharma et al. (2022a, b) employed green synthesis using biocompatible Zingiber officinale leaf extract as a reducing and capping agent to synthesis silver nanoparticles. Similarly, NaBH4 was used as reducing agent in the chemical synthesis process. The results demonstrated that silver nanoparticles produced by green approach had a superior antibacterial activity. Additionally, the plant-mediated nanoparticle synthesis offers a sustainable synthesis route and reduces environmental pollution since the plant extract is easily disposed without environmental harm compared to NaBH4. In another case study, Mahaya et al. (2023) looked at the implementation of SDGs in a pasteurized milk industry. The study indicated that implementing SDGs in this growing industry involved reducing, recycling and reusing it safely.

To implement the SDGs, growing industries would have to prioritize and align relevant SDGs targets with their operational process. Through adoption of green synthesis and integration of green nanotechnology into environmental policies, developed and developing nations can drive the adoption of eco-friendlier nanomaterials and production processes as they commit to sustainable consumption, clean energy and reduction of pollution.

Limitations of green nanotechnology in achieving SDGs targets

Green nanotechnology adoption, while holding benefits of long-term sustainability, it is in infancy stage and does face limitations such economic feasibility, scalability, technological difficulties, cost, inconsistent regulations, toxicity concerns and industry unacceptance that hinder its implementation by growing industries (Gupta et al. 2023; Kisimba et al. 2023). Integration of green nanotechnology requires careful considerations of these limitations to ensure successful and wider implementation in growing industries. Moreover, investing in green nanotechnology research, promoting education of green nanotechnology and SDGs, developing appropriate guidelines on implementing green nanotechnology to foster attainment of SDGs targets, and conducting a comprehensive assessment of nanotoxicity and environment impact can unlock the potential of green nanotechnology and progress toward achieving SDGs targets.

Green chemistry principles

The foundation of green chemistry consists of the twelve principles put forth by Paul Anastas and John Warner in their attempt to characterize a more environmentally friendly (or greener) chemical process or product (Chen et al. 2020). The development of green chemistry principles aimed to prevent pollution at its source by minimizing the use of hazardous chemicals and optimizing product yield in the preparation of nanomaterials (Madani et al. 2022). Though no reaction can be entirely green, by applying the following 12 green chemistry principles wherever appropriate, the overall detrimental effects of nanotechnology research and industry can be lessened (Ameta and Ameta 2023). Table 1 highlights the twelve principles of green chemistry, their interpretation and consideration in biogenic synthesis of metal nanoparticles to promote sustainable and green nanotechnology.

Table 1 Twelve principles of green chemistry, their interpretation and consideration in synthesis to promote green nanotechnology
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Promoting sustainable nanotechnology through biogenic synthesis of nanoparticles

Developing nanomaterials through easy, affordable, environmentally friendly, and green methods is the cornerstone of sustainable nanotechnology. The process of creating nanomaterials through biogenic synthesis is one such technique that is safe, economical, ecologically friendly, and clean (Ravikumar and Prakash 2022). The production of nanoparticles through biogenic synthesis is becoming a viable, affordable, sustainable, biocompatible, and alternative method to chemical and physical methods (Chauhan et al. 2023). This production of safe, non-toxic, economical, energy-efficient, and metallic nanoparticles using plants and microbes like viruses, bacteria, fungi, and algae has been extensively studied, increasing significantly in the recent years. Green synthetic technology undoubtedly has a significant impact on improving biological compatibility and lowering environmental toxicity and pollution (Chopra et al. 2022).

Typically, the synthesis of nanoparticles requires the use of multiple reagents, such as solvents, reducing and stabilizing agents, precursors, and in certain situations, energy to attain the ideal temperature for reduction (Shafey 2020). Thus, green reagents and green energies have been investigated in an effort to develop a green approach. Scholars have explored a variety of phytochemical constituents in plants and plant extracts that can function as solvents, stabilizers, or capping agents as alternatives to the hazardous reagents (Sharma et al. 2022a, b). Furthermore, studies on the use of microwave, gamma, and ultraviolet radiation have shown that these methods can both reduce and produce uniform heating in nanoparticle synthesis (Guo et al. 2020). Table 2 summarizes studies on biogenic synthesis of metal nanoparticles with emphasize on the green solvent used, green energy-efficient process and biocompatible reagents used as reducing, capping or stabilizing agents. These studies are reviewed in the subsequent sections based on the green solvent, green energy-efficient process, and biocompatible biological components used as reducing, stabilizing and capping agents.

Table 2 Summary of studies on biogenic synthesis of metal nanoparticles utilizing green solvent, green energy-efficient process and biocompatible materials as reducing, capping or stabilizing agents
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Sustainable nanotechnology through use of safer solvents in biogenic synthesis

The use of solvent systems is an essential step in any synthesis process. The green solvent method employs green solvents, e.g., distilled water instead of organic solvents during the synthesis of nanoparticles. In addition to their low toxicity and ability to be renewed, these green solvents have the advantage of not harming human health or ecosystems (Tilahun Bekele et al. 2021). The best solvent is none at all, and water is the perfect solvent if one is required. Water is always thought to be the best, affordable, widely available and most appropriate solvent system. Water has been used as a solvent for the synthesis of several metal nanoparticles such as silver, copper, gold, palladium, iron, platinum, etc. Supercritical fluids, ionic liquids and liquid polymers such as PEG are also green solvents that can be considered in synthesis of metal nanoparticles. However, studies using these solvents are scanty, pointing a gap that needs to be explored in future studies. In this subsection, we review metal nanoparticles that have been synthesized using water as a green solvent.

Silver nanoparticles have been synthesized by many researchers using water as a green solvent at room temperature (Cardoso-Avila et al. 2021; Gharari et al. 2023; Odeniyi et al. 2020; Razavi et al. 2020; Rodríguez-Félix et al. 2021; Suganya et al. 2020; Tamilarasi & Meena 2020; Wang et al. 2018a, b; Zangeneh et al. 2019a, b). For instance, Wang and co-workers synthesized and characterized silver nanoparticles in aqueous medium. The average size of the AgNPs was 25–35 nm with a zeta potential of − 20.17 mV, indicating good stability. Additionally, the AgNPs exhibited high scavenging activity and strong inhibition against selected bacteria (Wang et al. 2018a, b). In another study, Rodríguez-Felix and co-workers synthesized silver nanoparticles in water at room temperature using safflower aqueous extract rich in proteins, polysaccharides and polyphenols. They obtained uniform and spherical nanoparticles with mean size of 8.67 nm which demonstrated antimicrobial properties (Rodríguez-Félix et al. 2021). Additionally, Tamilarasi and Meena synthesized silver nanoparticles with enhanced antibacterial activity using Gomphrena globosa leaf aqueous extract as a reducing agent and stabilizer in water medium at room temperature (Tamilarasi and Meena 2020).

Gold nanoparticles have also been synthesized using water as a green solvent at ambient temperature (Cardoso-Avila et al. 2021; Fadaka et al. 2021; Rajeshkumar et al. 2021; Shakerimanesh et al. 2022). For instance, Shakerimanesh and co-workers synthesized spherical gold nanoparticles in water using Haplophyllum obtusifolium aqueous extract, characterized and tested their cytotoxicity against breast cancer cell line (Shakerimanesh et al. 2022).

Palladium nanoparticles have also been synthesized at room temperature using water as the solvent medium (Bathula et al. 2020; Razavi et al. 2020). Bathula and co-workers employed ultrasonically driven production of palladium nanoparticles using Coleus amboinicus aqueous extract at room temperature for 30 min. This novel process was simple and fast producing spherical palladium nanoparticles with a mean size of 45 nm (Bathula et al. 2020).

Iron nanoparticles too have been synthesized at room temperature in a water medium (Jamzad and Kamari Bidkorpeh 2020; Salem et al. 2019; Zangeneh et al. 2019a, b). For instance, Salem and co-workers used water to produce iron oxide nanoparticles biogenically at room temperature with the use of algae species. The spherical nanoparticles had a size of between 11.24 and 33.71 nm and possessed a wide spectrum of antimicrobial activity (Salem et al. 2019). Similarly, Jamzad and Bidkorpeh synthesized iron nanoparticles using Laurus nobilis leaves aqueous extract. The nanoparticles were spherical and hexagonal with antibacterial and antifungal activity (Jamzad and Kamari Bidkorpeh 2020).

Copper nanoparticles have also been synthesized utilizing water as green solvent at room temperature (Nzilu et al. 2023; Razavi et al. 2020). For instance, Nzilu and co-workers synthesized copper nanoparticles at room temperature using an aqueous extract of Parthenium hysterophorus as a reducing, capping and stabilizing agent. The nearly spherical copper nanoparticles had a mean size of 59.99 nm and possessed an ability to degrade rifampicin antibiotic (Nzilu et al. 2023). Figure 1 illustrates the biogenic synthesis of copper oxide nanoparticles in aqueous medium. Similarly, Jothiramalingam and co-workers synthesized copper nanoparticles utilizing aqueous extract of lemon flower at 60°. The nanoparticles were spherical with promising potential to inhibit E-coli, S typhi and S.aureus (Jothiramalingam et al. 2022).

Fig. 1
figure 1

Reproduced with permission from Nzilu et al. (2023)

Synthesis of copper nanoparticles in aqueous medium and characterization.

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Multiple nanoparticles have been synthesized using a biocompatible reducing and stabilizing agent (Nguyen et al. 2018; Razavi et al. 2020). For instance, Razavi and co-workers synthesized silver, copper and palladium nanoparticles using mulberry aqueous extract at room temperature. The synthesized AgNPs, CuNPs, and PdNPs were of spherical morphology and possessed antibacterial activity (Razavi et al. 2020). In another study, gum karaya extract in aqueous medium was used to synthesize gold, silver, platinum, copper oxide and palladium nanoparticles. The nanoparticles were stable over 6 months and exhibited biocidal and antimicrobial properties (Nguyen et al. 2018).

In conclusion, the use of safer solvents in the biogenic synthesis of metal nanoparticles is a growing area of interest and these studies collectively underscore the potential of biogenic synthesis using safer solvents such as water in the production of metal nanoparticles.

Sustainable nanotechnology by use of biocompatible materials in biogenic synthesis

Plants contain a wide variety of biocompatible phytochemical compounds that are used in the synthesis of nanomaterials. These compounds include flavonoids, alkaloid compounds, tannins, saponins, and others (Mohammadzadeh et al. 2022). Scholars have explored a variety of phytochemical constituents and plant extracts that can function as solvents, stabilizers, or capping agents as alternatives to the hazardous reagents (Sharma and Pathania 2022). In this subsection, we review studies that have used some of these biocompatible phytochemical compounds such as fucoidan, glycyrrhiza, cannabidiol, and other plant extracts in synthesis of metal nanoparticles.

Fucoidan, a polysaccharide, was used by Rajeshkumar et al. (2021) to serve as a reducing agent and stabilizer in synthesis of gold nanoparticles at room temperature using water as a solvent. Crystalline Au NPs of mean size of 31 nm were obtained and tested against cancer using HepG2 cell line. Figure 2 illustrates the biogenic synthesis of Au NPs using fucoidan as a reducing agent and stabilizer.

Fig. 2
figure 2

Reproduced with permission from Rajeshkumar et al. (2021)

Gold nanoparticle synthesis using fucoidan reducing agent and stabilizer.

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Glycyrrhiza, a hydrophilic polysaccharide extracted from licorice, was employed in photo-induced production of silver nanoparticles. The obtained glycyrrhiza stabilized silver nanoparticles with a size between 20 and 50 nm were incorporated into biopolymeric film and tested for their antibacterial activity (Cai et al. 2019). In another study, cannabidiol was utilized in reducing and capping of silver and gold nanoparticles in a microwave-assisted process. Both AgNPs and AuNPs were spherical, monodispersed with potential cytotoxic effect on human keratinocyte cells (Josiah et al. 2021).

Both silver and gold nanoparticles were synthesized by Cardoso-Avilla and co-workers using water as a solvent and phenolic compounds in aqueous Rose canina extract as reducing and capping agents at ambient temperature for 15 min. Stable, quasi-spherical nanoparticles of size between 26 and 34 nm were formed (Cardoso-Avila et al. 2021). In another study, Mohammed and co-workers synthesized platinum nanoparticles using olive leaf extract enriched with ascorbic and gallic acids, terpenoids, and amino acids in aqueous medium at room temperature. Spherical and compact nanoparticles with mean size of 9.2 nm were produced and their effects tested on aspartate aminotransferase activity (Mohammed et al. 2022).

In summary, the biogenic synthesis of metal nanoparticles utilizing biocompatible plant phytochemicals and extracts is a promising area of research, offering environmentally friendly and cost-effective methods for nanoparticle production. These studies collectively highlight the promising potential of plant phytochemicals in biogenic synthesis, emphasizing their ability to reduce and stabilize metal nanoparticles.

Sustainable nanotechnology by use of efficient green energy in biogenic synthesis

A range of studies have explored the biogenic synthesis of metal nanoparticles at room temperature, utilizing efficient green energies (Amina et al. 2020; Beden et al. 2022; Erdogan et al. 2019; Punnoose et al. 2021; Singh et al. 2019a, b; Strapasson et al. 2021; Wang et al. 2018a, b). The ability of biological processes to produce stable chemical nanoparticles with a spherical morphology and compact size with high energy efficiency is widely recognized (Rana et al. 2020). For instance, synthesis is carried at ambient temperature and/or by use of green energies such as microwave, UV or gamma radiation, and ultrasound. By using these modern energy transfer techniques instead of conventional methods, less energy is needed, making it a greener approach. Additionally, because this energy transfer techniques causes the constituents to heat quickly and uniformly, they offer uniform nucleation and growth conditions for nanomaterials. In this subsection, we discuss various studies that have employed green energy-efficient techniques such as gamma, UV, microwave energies in biogenic synthesis of metal nanoparticles.

Using gamma radiation energy, Beden and co-workers synthesized silver nanoparticles chitosan composite in aqueous medium at room temperature. The Gamma irradiation-assisted synthesis produced Ag NPs with a narrow sized distribution (Beden et al. 2022). In another study, instead of using gamma radiation, Singh and co-workers utilized Dunaliella salina aqueous extract to reduce and stabilize gold nanoparticles in presence of UV light for 75 min. The spherical AuNPs had an average size of 22.4 nm and demonstrated anticancer activity when tested on MCF7 cell line (Singh et al. 2019a, b).

Microwave irradiation has been employed as a green energy process in nanoparticle synthesis (Amina et al. 2020; Erdogan et al. 2019; Punnoose et al. 2021; Strapasson et al. 2021; Wang et al. 2018a, b). For instance, Punnoose and co-workers used microwave energy to synthesis gold nanoparticles together with Myristica fragrans aqueous extract to reduce and cap the nanoparticles. The nanoparticles had average size of 18.72 nm with catalytic potential to degrade environmental pollutants (Punnoose et al. 2021). Similarly, Amina and co-workers successfully synthesized silver and gold alloy nanoparticles using microwave irradiation in presence of Asparagus racemosus aqueous extract. Both nanoparticles were of spherical morphology and showed antimicrobial and immunomodulatory potential (Amina et al. 2020). Similarly, Strapasson and co-workers produced silver nanoparticles using glycerol or glycerol/water as green solvent, starch as reducing and stabilizing agent and microwave irradiation and green energy (Strapasson et al. 2021). They produced highly stable nanoparticles for photogeneration as illustrated in Fig. 3. This novel approach combines the use of green solvent, biocompatible starch and microwave irradiation for the rapid biosynthesis of silver nanoparticles.

Fig. 3
figure 3

Microwave-assisted synthesis of AgNPs using glycerol or glycerol/water as green solvent and starch as a biocompatible reducing agent and stabilizer. Reused with permission from Strapasson et al. (2021)

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In conclusion, the biogenic synthesis of metal nanoparticles utilizing green energy methods has gained significant attention due to its eco-friendly and efficient nature. These green energy processes offer several advantages, including low energy requirements, cost-effectiveness, and minimal environmental impact. These studies collectively underscore the potential of biogenic synthesis, particularly in combination with green energy sources such as microwave irradiation, for the production of metal nanoparticles.

Summary and future perspective of biogenic synthesis and sustainable nanotechnology

Nanotechnology, as a key enabling technology, has grown tremendously leading to introduction of many nanomaterials for applications in various fields such as in drug delivery, diagnostics, catalysis, environmental remediation, and biomedical field. However, despite the numerous benefits of nanotechnology, production of nanomaterials makes use of unsustainable processes such as chemical methods and physical methods that have destructive consequences on the environment. Such processes go against the spirit of the sustainable development goals number viz. SDG 3.9, 6.3, 9.4, 12.4, and 12.5 that advocate for reducing number of deaths and illness from hazardous chemicals, pollutants and contaminants; reducing pollution and minimizing release of hazardous chemicals and pollutants into water environment to improve water quality; designing sustainable and resource-use efficient industries, and adoption of clean technologies and processes; reducing release of chemicals and waste into environment to minimize their negative impacts on humans and the environment; and preventing, reducing, recycling and reusing waste to substantially decrease its generation, respectively.

Green nanotechnology, which emphasizes sustainability and uses eco-friendly technologies, is promising and provides impeccable solutions that support realization of the sustainable development goals. Green synthesis of metal nanoparticles based on the principles of green chemistry aims to reduce or entirely eliminate the use of hazardous chemicals and minimize or possibly eliminate generation of pollutants. By use of eco-friendly solvents, maximization of atom economy to minimize waste generation and elimination of hazardous chemicals and waste to minimize impact on environment and human health, green synthesis substantially contributes to achieving the above-mentioned SDGs targets. Through adoption of green synthesis and integration of green nanotechnology into environmental policies, developed and developing nations can drive the adoption of eco-friendlier nanomaterials and production processes as they commit to sustainable consumption, clean energy, reduction of pollution and creation of a more sustainable future.

The future of biogenic synthesis of metal nanoparticles is promising, with a focus on green and sustainable nanotechnologies. However, biogenic synthesis and green nanotechnology solutions are still in the nascent phase which underscores the importance of continued research and development in this field. Additional research is needed to evaluate how nanotechnologies perform in actual production conditions, as well as to determine their effectiveness and long-term sustainability. It is also important to compare nanomaterials with current technologies to ensure their validity. Nevertheless, we believe that using biogenic synthesis and green nanotechnology to achieve sustainability, products and nanomaterials can be produced that support both the current and future generations without endangering human health or the environment.