A bio-inspired strategy for the interfacial assembly of graphene oxide with in situ generated Ag/AgCl: designing sustainable hybrid photocatalysts.

Herein, we report a polyamine-mediated assembly to integrate graphene oxide (GO) sheets with Ag/AgCl to fabricate a hybrid nanocomposite (GO-Ag/AgCl) at nearly neutral pH and ambient temperature. Inspired by the role of polyamines in the excellent integration of components to generate hierarchical nanostructures in biominerals such as diatoms, we showed that our strategy enabled the fabrication of GO-semiconductor composites with a well-integrated structure. The polyamines not only facilitated the in situ generation of Ag/AgCl, but also simultaneously allowed their interaction with GO suitable for visible light active photocatalysis, as revealed by the detailed characterization of the synthesized materials. Consequently, the GO-Ag/AgCl exhibited nearly 5 times higher photocatalytic activity and better photostability than Ag/AgCl under visible light irradiation. The nanocomposite reached its highest activity at the graphene content of 4.16 wt%. Thus, the assembly process represented an effective way to design hybrid composites. Moreover, as a sustainable photocatalyst, it facilitates effective separation of the photogenerated charge carriers at the interface, thereby improving activity and stability.

In Situ Strategy to Encapsulate Antibiotics in a Bioinspired CaCO3 Structure Enabling pH-Sensitive Drug Release Apt for Therapeutic and Imaging Applications.

Herein we demonstrate a bioinspired method involving macromolecular assembly of anionic polypeptide with cationic peptide-oligomer that allows for in situ encapsulation of antibiotics like tetracycline in CaCO3 microstructure. In a single step one-pot process, the encapsulation of the drug occurs under desirable environmentally benign conditions resulting in drug loaded CaCO3 microspheres. While this tetracycline-loaded sample exhibits pH dependent in vitro drug-release profile and excellent antibacterial activity, the encapsulated drug or the dye-conjugated peptide emits fluorescence suitable for optical imaging and detection, thereby making it a multitasking material. The efficacy of tetracycline loaded calcium carbonate microspheres as pH dependent drug delivery vehicles is further substantiated by performing cell viability experiments using normal and cancer cell lines (in vitro). Interestingly, the pH-dependent drug release enables selective cytotoxicity toward cancer cell lines as compared to the normal cells, thus having the potential for further development of therapeutic applications.

Polyamine-Mediated Interfacial Assembly of rGO-ZnO Nanostructures: A Bio-inspired Approach and Enhanced Photocatalytic Properties.

A bio-inspired approach for the fabrication of reduced graphene oxide (rGO) embedded ZnO nanostructure has been attempted to address issues pertaining to charge recombination and photocorrosion in ZnO for application as an effective photocatalyst. Herein we demonstrate the synthesis of rGO-ZnO nanostructures in a single step using polyamines, which simultaneously aid in the mineralization of ZnO nanostructures from zinc nitrate, reduction of graphene oxide (GO), and finally their assembly to form rGO-ZnO composite structures under environmentally benign conditions. The interspersed nanocomponents in the assembled heterostructures result in enhanced photocatalytic activity under UV light, indicating an effective charge separation of the excited electrons. Furthermore, the composite structure provides stability against photocorrosion for efficient recyclability of the catalyst.