Herein, we report the stabilization of silver and gold nanoparticles (Ag/Au NPs) on graphene oxide (GO) functionalized with PAMAM dendrimers. The grafting of the PAMAM dendrimers on GO has been investigated using TGA and Raman spectral studies and the stabilization of the Ag/Au NPs on the dendritic structures has been confirmed using XRD, UV-Vis and FT-IR spectra, SEM and TEM studies. The catalytic activity of the prepared nanocatalysts towards the degradation of organic azo dyes, namely methyl orange and congo red, has been tested. The prepared nanocatalysts were found to exhibit excellent catalytic activity towards the complete degradation of both methyl orange and congo red within only a few seconds.

Designing new materials for effective and targeted drug delivery is pivotal in biomedical research. Herein, we report on the development of a chitosan/carbon dot-based nanocomposite and investigate its efficacy as a carrier for the sustained release of dopamine drug. The carbon dots (CDs) were synthesized from the carbonization of chitosan and were further conjugated with chitosan (CS) to obtain a chitosan/carbon dot (CS/CD) matrix. Dopamine was later encapsulated in the matrix to form a dopamine@CS/CD nanocomposite. The cytotoxicity of IC-21 and SH-SY5Y cell lines was studied at various concentrations of the nanocomposite and the results demonstrate around 97% cell viability. The photoluminescence property revealed the characteristic property of the carbon dots. When excited at 510 nm an emission peak was observed at 550 nm which enables the use of carbon dots as a tracer for bioimaging. The HRTEM images and the D, G, and 2D bands of the Raman spectra confirm the successful synthesis of carbon dots and through DLS the particle size is estimated to be ∼3 nm. The release studies of the encapsulated drug from the composite were analyzed in an in vitro medium at different pH levels. The novelty of this method is the use of a non-toxic vehicle to administer drugs effectively towards any ailment and in particular, the carbon dots facilitate the consistent release of dopamine towards neurodegenerative diseases and tracing delivery through bioimaging.

Herein we report the covalent grafting of chitosan on graphene oxide (GO) followed by a simple approach for anchoring silver (AgNPs) and gold (AuNPs) nanoparticles onto a chitosan grafted graphene oxide surface by a NaBH₄ reduction method. Catalytic activity of prepared heterogeneous GO grafted chitosan stabilized silver and gold nanocatalysts (GO–Chit-Ag/AuNPs) was explored for the reduction of aromatic nitroarenes and degradation of hazardous azo dyes in the presence of NaBH₄. Both catalysts were found to exhibit excellent catalytic activity towards the reduction of aromatic nitroarenes and azo dyes degradation. Furthermore, the nanocatalysts were found to be selective towards the reduction of nitro groups in halonitroarenes without any dehalogenation under mild conditions.