Metallic and polymeric green nanoplatforms in oncology

Chemotherapy, the cornerstone of cancer treatment, although invaluable, is plagued with unbearable and occasionally life-threatening side effects due to its inability to discriminate between tumorous and healthy cells. Anticancer nanomedicines have gained prominence due to their site-specific delivery of chemotherapeutic agents. In comparison to traditional chemical and physical procedures, which add to the chemical burden of an already ailing body, biosynthesis of nanomaterials by plants and microorganisms has evolved as safer 'green' nano-manufacturing technology. While nanomedicines from plant extracts have been exhaustively researched, the use of microbes as potential nano factories for the production of metal nanoparticles has recently piqued interest. Many bacteria develop defence mechanisms to detoxify hazardous metal ions, which results in formation of nano scaled metals that can be used for numerous therapeutic applications. The intrinsic variability of microbiological systems, however, poses its own set of challenges, necessitating more stringent standardization protocols in order to create nanomaterials with reproducible attributes. In this paper, we review the emerging trends in the green biosynthesis of nanomaterials and their potential applicability in cancer therapeutics. We probe the microbial biosynthetic mechanistic pathways and the efforts taken to control the physicochemical characteristics of nanoparticles. The applications of metallic nanoparticles obtained from microbes as well as polymeric systems obtained from bacteria, fungi and seaweed in oncology are described in detail. The development of these nanomaterials as next-generation green anticancer drugs may result in a revolution in cancer therapeutics.