European Journal of Cardiovascular Medicine

Biofabrication is a revolutionary approach in healthcare which is used in manufacturing processes to produce biomaterials, devices, cells, tissues, and organs¹. It is a multidisciplinary field that involves the use of biological materials, cells, and biomaterials to create functional, living structures and tissues. It combines principles from biology, material science, engineering, and 3D printing technologies to produce complex biological constructs. Biofabrication aims to mimic and replace damaged or malfunctioning tissues, as well as to create tissue models for drug testing and disease research. The ultimate goal is to develop artificial organs and tissues for transplantation and regenerative medicine applications². Biofabrication has been defined as “the automated generation of biologically functional products with structural organization from living cells, bioactive molecules, biomaterials, cell aggregates, through bioprinting or bio assembly and subsequent tissue maturation processes”³. Nanotechnology is a rapidly progressive technology in the field of science and technology. Researchers showing more interest in this emerging branch. It involves the synthesis and application of materials having one of the dimensions in the range of 1–100 nm⁴. Nanoparticles exhibit unique properties and behaviours⁴. Because of these exclusive physicochemical properties, nanoparticles find endless applications in medicine⁵. Application of Nanoparticles can also be used in cosmetics, electronics, the food industry, and the chemical industry^6,7,8. The synthesis of nanoparticles can be categorized into the Top-down approach and bottom-up approach. In the top-down approach, nanoparticles are generated via size reduction⁹. In this approach, the appropriate bulk material breaks down into fine particles through the use of suitable lithographic techniques such as grinding, sputtering, and milling¹⁰.  whereas in the bottom-up approach, nanoparticles are generated from small entities such as atoms and molecules ⁹. This approach involves nanoparticle generation through the self-assembly of atoms into new nuclei, which further grow into a particle possessing nanoscopic dimensions and employing various chemical and biological methods¹¹.

Green synthesis of nanoparticles refers to the process of producing nanoparticles using environmentally friendly and sustainable methods. These methods typically avoid or minimize the use of hazardous chemicals and energy-intensive processes. Green synthesis has gained popularity due to its potential for reducing the environmental impact of nanoparticle production.

There are various methods for green synthesis of nanoparticles, and they often involve the use of natural or renewable materials. Here are some common approaches for the green synthesis of nanoparticles.

1. Plant-Mediated Synthesis: Many plant extracts contain bioactive: Compounds that can reduce metal ions to form nanoparticles. These plant-mediated methods are eco-friendly and cost-effective¹².
2. Microorganism-Mediated Synthesis: Certain microorganisms, such as bacteria, fungi, and yeast, can be used to synthesize nanoparticles. These microorganisms act as both reducing agents and stabilizers¹³.
3. Green Reducing Agents: Natural compounds like polyphenols, terpenoids, and vitamins can act as green-reducing agents for nanoparticle synthesis¹⁴.
4. Bioextraction and Phytoremediation: Some plants can accumulate metal ions from contaminated soils, and these metals can be extracted from the plant material to synthesize nanoparticles¹⁵.
5. Green Solvents: Using green and environmentally benign solvents, such as water or ethanol, for nanoparticle synthesis can reduce the environmental impact¹⁶.

Various ways to synthesize nanoparticles

As we discussed earlier, nanoparticles can be generated in various ways. Generating nanoparticles through physical and chemical pathways results in toxicity issues as well as environmental concerns. The physical pathway requires a large amount of space and generates a large amount of heat, raising the environmental temperature around the source material, and also very time consuming ¹⁷. The major drawback to the chemical method of nanoparticle generation is its use of toxic solvents and chemicals, which could cause great harm to our environment¹⁷. Therefore, the need for a different alternative in nanoparticle generation was felt across the globe, which led to the development of the green nanotechnology concept. A large number of nanoparticles generated with green nanotechnology have successfully been used in various applications¹⁷.

Microorganisms, including bacteria, fungi, and algae, have unique metabolic pathways that enable them to reduce metal ions to form nanoparticles. The most commonly used microorganisms for nanoparticle synthesis include Escherichia coli, Bacillus species, Saccharomyces cerevisiae, and various fungal strains. These microorganisms produce enzymes and metabolites that act as reducing and stabilizing agents, facilitating the synthesis of nanoparticles.

Mechanisms of green synthesis of nanoparticles using microorganisms

Microorganism-mediated synthesis refers to the processes in which microorganisms, such as bacteria, fungi, and algae, are employed to produce various substances through biological pathways. This synthesis can include the production of nanoparticles, organic compounds, and other valuable materials. The mechanisms involved in microorganism-mediated synthesis can vary depending on the specific application. Here, we are providing an overview of some common mechanisms.

1. Metal Nanoparticle Synthesis by Bacteria:

Reduction of metal ions to form nanoparticles. Microorganisms such as bacteria, especially those with metal-reducing capabilities, can convert metal ions into metallic nanoparticles²⁶.

2. Biomineralization by Algae:

Algae can facilitate the formation of minerals through a process called biomineralization, where they control the precipitation and deposition of minerals such as calcium carbonate²⁷.

3. Enzymatic Synthesis of Organic Compounds:

Mechanism: Microorganisms produce enzymes that catalyze specific reactions leading to the synthesis of organic compounds. This can include the production of biofuels, pharmaceutical intermediates, and other valuable chemicals²⁸.

4. Extracellular Polymeric Substance (EPS)-Mediated Synthesis:

Mechanism: Some microorganisms secrete extracellular polymeric substances (EPS) that can serve as templates for the synthesis of nanoparticles or as stabilizing agents²⁹.

5. Fungal-Mediated Synthesis:

Mechanism: Fungi can produce enzymes and metabolites that are involved in the reduction of metal ions and the synthesis of nanoparticles³⁰.

Figure2. Showing the common Mechanisms of green synthesis of Nanoparticles using microorganisms

It's important to note that the field of microorganism-mediated green synthesis is dynamic, and ongoing research continues to unveil new mechanisms and applications.

Advantages of Microorganism-Mediated Synthesis:

1. Environmentally Friendly:

Microorganism-mediated green synthesis is often carried out under mild and environmentally friendly conditions, reducing the need for harsh chemicals and minimizing the generation of hazardous by-products¹⁸.

2. Biocompatibility:

The resulting nanomaterials or compounds synthesized through microbial processes are often biocompatible and suitable for various biomedical applications¹⁹.

3. Cost-Effectiveness:

Microorganisms are relatively inexpensive and easy to culture, making the production process cost-effective compared to traditional chemical methods²⁰.

4. Reduced Energy Consumption:

Microorganism-mediated synthesis often occurs at ambient temperatures and pressures, reducing energy consumption compared to high-temperature chemical processes²¹.

5. Size and Shape Control:

Microorganisms offer control over the size and shape of the synthesized nanoparticles, providing versatility in tailoring the properties for specific applications²².

6. Biological Reducing Agents:

Microorganisms act as biological reducing agents, facilitating the reduction of metal ions into nanoparticles, contributing to the green nature of the synthesis process²³.

7. Potential for Large-Scale Production:

Microorganisms can be easily scaled up for large-scale production, making the process suitable for industrial applications²⁴.

8. Antibacterial and Antifungal Properties

Nanoparticles synthesized using microorganisms often exhibit inherent antibacterial and antifungal properties, making them suitable for medical applications, such as wound healing and infection control²⁵.

Biocompatibility: The synthesized nanoparticles often exhibit enhanced biocompatibility, making them suitable for biomedical applications.

Controlled Synthesis: Microorganisms offer control over the size and shape of nanoparticles through the regulation of reaction conditions.

Applications of Microorganism-Mediated Nanoparticles:

Biomedical Applications: Microorganism-synthesized nanoparticles find applications in drug delivery, imaging, and diagnostics due to their biocompatibility and controlled synthesis.

Catalysis: Nanoparticles produced by microorganisms serve as efficient catalysts in various chemical reactions, contributing to the field of green chemistry.

Environmental Remediation: Microbial nanoparticles play a role in environmental remediation by aiding in the removal of pollutants and heavy metals from contaminated water and soil.

Challenges and future perspectives:

Despite the promising advantages, challenges such as scalability, reproducibility, and the need for standardization in synthesis protocols persist. Future research should focus on optimizing and scaling up microorganism-mediated synthesis for industrial applications. Additionally, understanding the molecular mechanisms involved in the synthesis process can lead to the development of engineered microorganisms with enhanced nanoparticle synthesis capabilities.

Biofabrication is a revolutionary approach in healthcare, combining biology, material science, engineering, and 3D printing technologies to create functional, living structures and tissues. Nanotechnology, a rapidly progressive technology, involves the synthesis and application of materials with dimensions in the range of 1–100 nm. Green synthesis of nanoparticles refers to the process of producing nanoparticles using environmentally friendly and sustainable methods, typically avoiding or minimizing the use of hazardous chemicals and energy-intensive processes. Common approaches for green synthesis of nanoparticles include plant-mediated synthesis, microorganism-mediated synthesis, green reducing agents, bio extractions and phytoremediation, and green solvents. These methods often involve the use of natural or renewable materials, such as plant extracts with bioactive compounds, microorganism-mediated synthesis, and bio extractions and phytoremediation. Green synthesis has gained popularity due to its potential for reducing the environmental impact of nanoparticle production. Microorganism-mediated synthesis is a green synthesis method that uses microorganisms to reduce numerous advantages, including biocompatibility, cost-effectiveness, reduced energy consumption, size and shape control, and biological reducing agents. The most commonly used microorganisms for nanoparticle synthesis include Escherichia coli, Bacillus species, Saccharomyces cerevisiae, and various fungal strains. Enzymes such as reductases, nitrate reductases, and quinones play crucial roles in catalyzing reduction reactions. The extracellular synthesis of nanoparticles prevents intracellular toxicity and simplifies downstream processing. Microorganism-synthesized nanoparticles are suitable for various applications, including drug delivery, imaging, and diagnostics. They also serve as efficient catalysts in chemical reactions, contributing to green chemistry. Additionally, microorganism-synthesized nanoparticles can be used in environmental remediation by removing pollutants and heavy metals from contaminated water and soil. The mechanisms involved in microorganism-mediated synthesis can vary depending on the specific application, but some common mechanisms include metal nanoparticle synthesis by bacteria, biomineralization by algae, enzymatic synthesis of organic compounds, and extracellular synthesis.

1. Pavlovich MJ, Hunsberger J, Atala A. Biofabrication: a secret weapon to advance manufacturing, economies, and healthcare. Trends in Biotechnology. 2016 Sep 1;34(9):679-80.

1. Groll J, Boland T, Blunk T, Burdick JA, Cho DW, Dalton PD, Derby B, Forgacs G, Li Q, Mironov VA, Moroni L. Biofabrication: reappraising the definition of an evolving field. Biofabrication. 2016 Jan 8;8(1):013001.

3. Wei Z, Yu X, Chen S, Cong R, Wang H, Shi Q, Fukuda T, Sun T. Magnetically-Assisted Microfluidic Printing for the Fabrication of Anisotropic Skeletal Muscle Structure. IEEE Robotics and Automation Letters. 2023 Feb 23;8(5):2661-7.
4. Hussain I, Singh NB, Singh A, Singh H, Singh SC. Green synthesis of nanoparticles and its potential application. Biotechnol Lett 2016;38(4):545-60.
5. Azzazy  HM, Mansour MM, Samir TM, Franco R. Gold nanoparticles in the clinical laboratory: principles of preparation and applications. Clin Chem Lab Med 2012;50(2):193-209.
6. Alanazi  FK, Radwan  AA, Alsarra  IA. Biopharmaceutical applications of nanogold. Saudi Pharm J 2010;18(4):179-93.
7. Maekawa K, Yamasaki K, Niizeki T, Mita M, Matsuba Y, Terada N, Saito H. Drop-ondemand laser sintering with silver nanoparticles for electronics packaging. IEEE Trans Compon Packag Manuf Technol 2012;2(5):868-77.
8. Sanguansri  P, Augustin  MA. Nanoscale materials development–a food industry perspective. Trends Food Sci Technol 2006;17(10):547-56.
9. Sepeur S. Nanotechnology: technical basics and applications. Vincentz Network GmbH & Co KG; 2008.
10. Meyers MA, Mishra A, Benson DJ. Mechanical properties of nanocrystalline materials. Prog Mater Sci 2006;51(4):427-556.
11. Thakkar KN, Mhatre SS, Parikh RY. Biological synthesis of metallic nanoparticles. Nanomed Nanotechnol Biol Med 2010;6(2):257-62.
12. Song JY, Kim BS. Biological synthesis of bimetallic Au/Ag nanoparticles using Persimmon (Diopyros kaki) leaf extract. Korean Journal of Chemical Engineering. 2008 Jul; 25:808-11.
13. Sastry M, Ahmad A, Khan MI, Kumar R. Biosynthesis of metal nanoparticles using fungi and actinomycete. Current science. 2003 Jul 25:162-70.
14. Shankar SS, Rai A, Ahmad A, Sastry M. Controlling the optical properties of lemongrass extract synthesized gold nanotriangles and potential application in infrared-absorbing optical coatings. Chemistry of Materials. 2005 Feb 8;17(3):566-72.
15. Gardea-Torresdey JL, Parsons JG, Gomez E, Peralta-Videa J, Troiani HE, Santiago P, Yacaman MJ. Formation and growth of Au nanoparticles inside live alfalfa plants. Nano letters. 2002 Apr 10;2(4):397-401.
16. Nadagouda MN, Varma RS. Green synthesis of silver and palladium nanoparticles at room temperature using coffee and tea extract. Green Chemistry. 2008;10(8):859-62.
17. Pal G, Rai P, Pandey A. Green synthesis of nanoparticles: A greener approach for a cleaner future. InGreen synthesis, characterization and applications of nanoparticles 2019 Jan 1 (pp. 1-26). Elsevier.
18. Rai M, Ingle A. Role of nanotechnology in agriculture with special reference to management of insect pests. Applied microbiology and biotechnology. 2012 Apr; 94:287-93.
19. Mittal AK, Chisti Y, Banerjee UC. Synthesis of metallic nanoparticles using plant extracts. Biotechnology advances. 2013 Mar 1;31(2):346-56.
20. Husseiny MI, Abd El-Aziz M, Badr Y, Mahmoud MA. Biosynthesis of gold nanoparticles using Pseudomonas aeruginosa. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 2007 Jul 1;67(3-4):1003-6.
21. Iravani S. Bacteria in nanoparticle synthesis: current status and future prospects. International scholarly research notices. 2014;2014.
22. Singh P, Kim YJ, Singh H, Wang C, Hwang KH, Farh ME, Yang DC. Biosynthesis, characterization, and antimicrobial applications of silver nanoparticles. International journal of nanomedicine. 2015 Mar 31:2567-77.
23. Kalimuthu K, Babu RS, Venkataraman D, Bilal M, Gurunathan S. Biosynthesis of silver nanocrystals by Bacillus licheniformis. Colloids and surfaces B: Biointerfaces. 2008 Aug 1;65(1):150-3.
24. Mohanpuria P, Rana NK, Yadav SK. Biosynthesis of nanoparticles: technological concepts and future applications. Journal of nanoparticle research. 2008 Mar; 10:507-17.
25. Saifuddin N, Wong CW, Yasumira AA. Rapid biosynthesis of silver nanoparticles using culture supernatant of bacteria with microwave irradiation. Journal of Chemistry. 2009 Oct; 6:61-70.
26. Kalishwaralal K, Deepak V, Pandian SR, Kottaisamy M, BarathManiKanth S, Kartikeyan B, Gurunathan S. Biosynthesis of silver and gold nanoparticles using Brevibacterium casei. Colloids and surfaces B: Biointerfaces. 2010 Jun 1;77(2):257-62.
27. Kurtz AC et al. Biotic and abiotic influences on microbially-mediated mineralization of gypsum in a hypersaline lake stromatolite. Chemical Geology. 2012;304-305,119-130.
28. Chisti Y. Biodiesel from microalgae. Biotechnology advances. 2007 May 1;25(3):294-306.
29. Klaus-Joerger T, et al. Biochemical analysis of the interaction between silver ions and bacterial biofilms. Biotechnology and Bioengineering. 2001;75(3):344-352.
30. Mukherjee P, Ahmad A, Mandal D, Senapati S, Sainkar SR, Khan MI, Parishcha R, Ajaykumar PV, Alam M, Kumar R, Sastry M. Fungus-mediated synthesis of silver nanoparticles and their immobilization in the mycelial matrix: a novel biological approach to nanoparticle synthesis. Nano letters. 2001 Oct 10;1(10):515-9.