Background: Nanotechnology is the promising field of science which deals with the production and utilization
of material under nanoscale dimensions. The nanoscale regime provides exceptional applications in various fields of
science due to their large surface to volume ratio and many valuable properties. Hence, the production and use of
nanomaterials are the prominent areas of modern research. Amongst the nanomaterials, metal oxide NPs have gained
much attention due to their vast number of applications in different areas including electrochemical applications, dye
degradation, catalysis and are known to be the exceptional entities in the battle against different pathogens. The metal
oxides are viably synthesized through chemical methods that requires the use of many noxious chemicals. Henceforth, it is
the demand of the modern world to carry out research on the synthesis of metal oxide nanomaterials through eco-friendly,
greener and non-toxic routes. Thus, various green methods are employed to engineer the metals oxide NPs by using
different greener, cheaper and eco-friendly sources, employing the use of plant extracts, bacteria, fungi and other
biological bodies. The present review covered the green synthesis of CuO, ZnO, TiO2 NPs and their applicability towards
different pathogens and environmental remediation reported from 2015 to till date.
Objective: The exceptional catalytic properties, environmental and antimicrobial applications of metal oxide especially
CuO, ZnO, TiO2, are the main prominence of this review articles. The most cost-effective and greener routes for synthesis
of CuO, ZnO, TiO2, are discussed in the present review. Till date various green synthetic methods for preparation of
mentioned nanoparticles and their applicability towards different pathogens and degradation of different hazardous dye
with some electrochemical applications has been thoroughly covered in this review.
Conclusion: The biosynthesis of metal oxide NPs using greener and eco-friendly approaches have been the attentive area
in the last decade. Green synthesis requires the chemical-free active component from biological sources which act as both
the reducing and stabilizing agent for the size and shape-controlled production of NPs. The future vision of bacterial,
fungal and plant-mediated production of NPs includes the postponement of laboratory-based work to large industrial
scale, exposition of different phytochemicals involved in the biosynthesis of NPs using bioinformatics techniques and
stemming the real mechanism involved in preventing the growth of pathogenic bacteria, fungi, and algae. The plant-mediated NPs can have diverse applications in the arena of pharmaceutical, food and cosmetic industries and thus became
a vital area of modern research.