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

This study focuses on developing a novel hybrid nanomaterial composed of gold nanoparticle decorated with carbon dots, termed AuNP@C-dot, 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, X-ray photoelectron spectra, 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 signaling of C-dots and the scattering signaling of AuNPs.<i>In vitro</i>studies using human lung cell lines (A549 and BEAS-2B) confirmed the multiplexed imaging and revealed efficient cellular uptake and subcellular localization of AuNP@C-dots, including nuclear translocation, which is critical for radiotherapy and photodynamic therapy. Cell viability assessments utilizing a colorimetric assay for measuring cell metabolic activity and a colony formation assay demonstrated good biocompatibility of AuNP@C-dots at relevant concentrations. It can be envisioned that the AuNP@C-dot hybrid system may improve the detection and monitoring of cell health and disease due to its dual-modal imaging capability. Furthermore, they could be used for supervising controlled release of therapeutic agents, tailored for enhanced treatment efficacy. This study demonstrates 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.