Developing gold nanoparticles decorated with carbon-dots for multiplexed cellular imaging

This study focuses on the development of a novel hybrid nanomaterial composed of gold nanoparticles decorated with carbon dots termed C-dot@AuNP as a versatile platform for multiplexed imaging. Structural and spectral characterizations confirmed the successful conjugation of C-dots to AuNPs via covalent bonding, as evidenced by FTIR, XPS, HRTEM analyses and UV-Vis and fluorescence spectroscopies. The fluorescence intensities of C-dots are doubled through the conjugation to the AuNPs. The conjugation of fluorescent C-dots to plasmon-resonant AuNPs enables simultaneous multicellular imaging by taking advantage of the fluorescent signalling of C-dots and the scattering signalling of AuNPs. In vitro studies using human lung cell lines (A549 and BEAS-2B) confirmed the multiplexed imaging and revealed efficient cellular uptake and subcellular localization of C-dot@AuNPs, including nuclear translocation, which is critical for radiotherapy applications. Cytotoxicity assessments exploiting MTT and colony formation assays demonstrated good biocompatibility at relevant concentrations. It can be envisioned that the C-dot@AuNP hybrid system could enhance disease detection and monitoring due to its dual-modal imaging capability and could be used for advanced diagnostics where controlled release of therapeutic agents could be tailored for enhanced treatment efficacy. This study highlights the potential of C-dot-conjugated AuNPs as a multifunctional tool with inherent control mechanisms for the next-generation cellular analysis, drug administration, and diagnostic strategies.