By H. Chopra, T. Bin Emran, Simona Cavalu & al

Algae, plants, bacteria, and fungus have been employed to make energy-efficient, low-cost, and nontoxic metallic nanoparticles in the last few decades. Despite the environmental advantages of using green chemistry-based biological synthesis over traditional methods as discussed in this article, there are some unresolved issues such as particle size and shape consistency, reproducibility of the synthesis process, and understanding of the mechanisms involved in producing metallic nanoparticles via biological entities. Consequently, there is a need for further research to analyze and comprehend the real biological synthesis-dependent processes. Copyright: H. Chopra, Simona Cavalu & al

FACTORS AFFECTING BIOSYNTHESIS OF NANOPARTICLES: Nanoparticles creation from biological extracts may also be affected by reaction conditions. Studies have shown that a reaction solution’s pH has a significant impact on the production of the nanoparticles that result. The form and size of the generated nanoparticles may be affected by changes in the reaction pH. When comparing lower acidic pH values to higher acidic pH values, bigger particles are produced. The bigger particles (25–85 nm) were generated at pH two whereas the smaller particles (5–20 nm) were created at pH three and four in a research using Avena sativa biomass (Armendariz et al., 2004). Particle aggregation may have been caused by the lack of functional groups at pH 2, according to the researchers. The bacteria Rhodopseudomonas capsulate was shown to produce gold nanoparticles in a similar manner. It was discovered that, with a pH rise of 7, spherical particles measuring 10–20 nm were present. Nanoplates were formed when the reaction pH was lowered to 4 (He et al., 2007). Copyright: H. Chopra, Simona Cavalu &al.

RECYCLABILITY AND REUSABILITY OF
GREEN-SYNTHESIZED NANOPARTICLES: The areas of materials engineering and nanotechnology are increasingly concerned with sustainability techniques, frameworks, and metrics in an attempt to mitigate
environmental and health concerns connected with the manufacturing, use, and disposal of innovative nanomaterials (Dhingra et al., 2010). Veisi et al., synthesized Ag nanoparticles based on Thymbra spicata, the plant being rich source of thymol, carvacrol and myrcene (Veisi et al., 2018). In spite of the significant catalytic activity of Ag Nanoparticles/Thymbra. When Ag NPs/Thymbra were separated and reapplied in RhB and MB colour degradation, their recycling efficiency was determined correspondingly. Similarly, researchers developed copper nanoparticles using Commersonia bartramia extract and immobilized using Al2O3 surface (Nasrollahzadeh et al., 2019). The catalyst was able to show significant changes upto 7th cycle, for reduction of 2,4-dinitrophenylhydrazine. Copyright: H. Chopra, Simona Cavalu & al.

Despite the environmental advantages of using green chemistry based biological synthesis over traditional methods as discussed in this article there are some unresolved issues such as particle size and shape consistency, reproducibility of the synthesis process, and understanding of the mechanisms involved in producing metallic nanoparticles via biological entities. Therefore, there is a need for further research to analyze and
comprehend the real biological synthesis dependent processes. This is a vastly untapped subject that needs much more research investment to properly leverage the green manufacturing of metallic nanoparticles through living entities. Copyright: H. Chopra, Simona Cavalu &al.

Full text at https://www.frontiersin.org/articles/10.3389/fbioe.2022.874742/full