Chemical, physical and mechanical methods of nanomaterial preparation are still regarded as mainstream methods, and the scientific community continues to search for new ways of nanomaterial preparation. The major objective of this review is to highlight the advantages of using green chemistry and bionanotechnology in the preparation of functional low-cost catalysts. Bionanotechnology employs biological principles and processes connected with bio-phase participation in both design and development of nano-structures and nano-materials, and the biosynthesis of metallic nanoparticles is becoming even more popular due to; (i) economic and ecologic effectiveness, (ii) simple one-step nanoparticle formation, stabilisation and biomass support and (iii) the possibility of bio-waste valorisation. Although it is quite difficult to determine the precise mechanisms in particular biosynthesis and research is performed with some risk in all trial and error experiments, there is also the incentive of understanding the exact mechanisms involved. This enables further optimisation of bionanoparticle preparation and increases their application potential. Moreover, it is very important in bionanotechnological procedures to ensure repeatability of the methods related to the recognised reaction mechanisms. This review, therefore, summarises the current state of nanoparticle biosynthesis. It then demonstrates the application of biosynthesised metallic nanoparticles in heterogeneous catalysis by identifying the many examples where bionanocatalysts have been successfully applied in model reactions. These describe the degradation of organic dyes, the reduction of aromatic nitro compounds, dehalogenation of chlorinated aromatic compounds, reduction of Cr(VI) and the synthesis of important commercial chemicals. To ensure sustainability, it is important to focus on nanomaterials that are capable of maintaining the important green chemistry principles directly from design inception to ultimate application.
Nanotechnology is an emerging cutting-edge technology, which involves interdisciplinary subjects, such as physics, chemistry, biology, material science and medicine. Different methods for the synthesis of nanoparticles have been discussed here. Although physical and chemical methods have been successfully used to synthesize nanoparticles, the use of hazardous chemicals and synthesis at high temperature is a matter of concern. Hence, there is a necessity to develop eco-friendly techniques for the synthesis of nanoparticles. Biosynthesis of nanoparticles by fungi, bacteria, actinomycetes, lichen and viruses have been reported eco-friendly. Moreover, the fungal system has emerged as an efficient system for nanoparticle synthesis as fungi possess distinctive characters including high wall binding capacity, easy to culture and simpler biomass handling, etc. In this review, we have discussed fungi as an important tool for the fabrication of nanoparticles. In addition, methods and mechanism for synthesis of nanoparticles and its potential applications have also been discussed.
