Bioinspired Nanotheranostic Agents: Synthesis, Surface Functionalization, and Antioxidant Potential.

Bioinspired synthesis of nanomaterials is highly advantageous as a natural and cost-effective resource. Development of noble metal nanotheranostic agents was achieved through bioinspired synthetic routes. These biosynthesized nanoparticles were characterized by various analytical techniques including absorption spectroscopy, FTIR and electron microscopy (SEM and TEM). A large number of medicinal plants were screened, among which Potentilla fulgens (PF, vajradanti) and Camellia sinensis (CS, green tea) were found to produce nanomaterials with higher yields. Plant (PF and CS) mediated metallic nanoparticles had added advantage of metal reduction and simultaneous phytochemical capping over chemically synthesized procedures, which require multiple reagents. Antioxidant potential of the nanomaterials was determined by in vitro antioxidant assays confirming substantial antioxidant properties, which was due to the presence of phytochemicals on the nanoparticle surface. Flavonoids and catechins on the nanomaterial surface served as the supplier of hydroxyl groups for further derivatization. The surface of the nanoparticles was engineered by conjugating imaging and therapeutic moieties, resulting in the formation of theranostic nanoagents. The multimodal agents were characterized and the extent of drug loading was determined to validate the efficacy of those nanoconjugates. These bioinspired multimodal nanoprobes can serve as essential diagnostic and therapeutic tools in ongoing biomedical research.