Paradoxical Features Empower Biogenic Silver Nanoparticles

Silver nanoparticles (AgNPs) have drawn great attention, owing to their unique physico-chemical and biological properties and various applications, particularly in the biomedical field. In addition to conventional chemical and physical methods, materials scientists have been exploring the capabilities endowed by several bioresources, such as plants, bacteria, fungi and algae, in the cost-effective and eco-friendly production of AgNPs. This review article provides a comprehensive overview of the current state of research on the bioapplications of biogenic AgNPs (bio-AgNPs). The various bioresources used and methodologies followed to synthesize bio-AgNPs are briefly examined, along with some aspects of the underlying mechanisms. Then, the review surveys the toxicity of AgNPs, in general, and presents the unique biological properties of bio-AgNPs. Furthermore, the review details numerous applications of bio-AgNPs with paramount importance to human health, such as the control of infectious disease vectors, cancer therapy, antibiofilm activity and environmental remediation. Importantly, the review highlights the paradoxical effect of these nano-objects since they specifically seem to exert their action solely on targeted cells and (micro)organisms. By featuring the unique advantages of biogenic methods and their challenges, this article aims at serving as a valuable resource to attract research on bio-AgNPs and elicit further developments towards the scalable and sustainable production of AgNPs for large scale industrial and clinical use.