Bio-derivatized and Silver Modified Carbon Dot Based Nanocomposite in Multiple Mode Detection, Catalytic Reduction, and Biocidal Applications

Biomass derived carbon dots (CDs) were prepared hydrothermally from Hemigraphis colorata leaves for the first time. It was then used for the fabrication of composite based on silver nanoparticles (CD-AgNP). Bio derivatization of nanomaterials has various advantages, including availability, low cost, and minimal toxicity. The composite was used extensively to accomplish five major applications. It detected cephalexin with exceptional selectivity and sensitivity using a fluorescence recovery-based method. Rhodamine B (RhB) and malachite green (MG), two polluting dyes, were catalytically reduced by the composite in seconds with a high degradation efficiency. The composite easily detected mercuric ions as a colorimetric probe, enabling mercury identification with the naked eye. With an extremely low limit of detection, the composite was also able to detect mercuric ions electrochemically. Both gram-positive and gram-negative bacteria were successfully inhibited by the antibacterial activity of the CD-AgNP composite. The mechanisms in each application have been elaborated using appropriate analysis. This is the first investigation on the production of CDs and CD-AgNP composite using Hemigraphis colorata leaves. This work stands out because the proposed composite was fully exploited to its maximum potential. In a nutshell, all the aforesaid applications could be effectively carried out using a single nanocomposite that was produced using a fairly simple green strategy with a strong commitment towards sustainable environment.