Green Synthesis of Metal Oxide Nanoparticles Using Plant Extracts and Their Applications in Antimicrobial and Environmental Remediation: A Sustainable Approach

Abstract

With this emerging need for materials that are environmentally friendly, sustainable synthesis methods that reduce the use of harmful chemicals, energy use and environmental impact have gained considerable interest. Thus, the ability to synthesize metal oxide nanoparticles by plants seems to be a green technology alternative to the traditional physical and chemical methods, but evidence is still weak on the phytochemical mechanisms underlying the synthesis of nanoparticles and their synergistic applications in antimicrobial activity and environmental remediation (Jadoun et al., 2021; Iravani, 2011). To critically examine the status quo of knowledge, this study used systematic review of peer-reviewed literature and thematic synthesis and qualitative content analysis to identify trends, mechanistic insights, technological advances and gaps in literature. The findings are that various phytochemicals from plants such as polyphenols, flavonoids, terpenoids, alkaloids, proteins and reducing sugars act in a synergistic way as reducing, stabilizing and capping agents, which allow a controlled synthesis of metal oxide nanoparticles with desired physicochemical properties. The surveyed evidence also confirms that these nanoparticles possess a wide spectrum antimicrobial activity attributed to the induction of oxidative stress, disruption of membrane and biomolecular damage inside the cells, along with the high potential for environmental remediation via photocatalytic degradation of organic contaminants, heavy metal adsorption and wastewater treatment (Ahmed et al., 2016; Khan et al., 2022). Plant-mediated synthesis approaches consistently show greater sustainability than conventional approaches, through decreased use of toxic reagents, lower energy consumption, increased biocompatibility, and by adhering to the principles of circular bioeconomy. The study contributes to the theoretical understanding by embedding the concepts and principles of green chemistry and nanotechnology together within a unified conceptual framework and offers practical inputs for the design of an eco-friendly, scalable-approach to the production of nanoparticles. However, the variability in plant metabolites, lack of process standardization, and lack of validation in the industrial scale are still important limits. Standardized synthesis methods, mechanistic molecular studies, life cycle analysis and pilot scale commercialization should be analyzed in future studies to facilitate sustainable implementation in the industry. Overall, plant-mediated green synthesis is a scientifically sound and eco-friendly route to obtain multifunctional metal oxide nanoparticles which can simultaneously combat antimicrobial resistance, environmental pollution, and promote sustainable nanotechnology.