Novel photodamage-free bioimaging and anticancer studies using ultra-bright near-infrared emitting nitrogen-doped carbon dots intercalated Zn(OH)2 nanosheets

Near-infrared (NIR) fluorescence emitting probes are of potential interest in the field of bioimaging due to good penetration and minimal photodamage to tissues. Despite the remarkable fluorescence properties of carbon dots (CDs), their low emission quantum yield and need for surface modification limit their applicability. CDs are intercalated into multilayer structures to minimize internal quenching and modify surface functional groups, which improve sensitivity and selectivity. Layered zinc hydroxide (LZH) stands out among other layered materials because of its stability, biocompatibility, luminescence, and capacity to be used as a drug delivery system. By incorporating LZH with fluorophore can transform it as prominent bioimaging probe. In this study, we used a direct and low-cost microwave-assisted technique to successfully intercalate nitrogen-doped carbon dots (NCDs) in layers of zinc hydroxide (NCLZH). Formation of layers of NCLZH is supported by the HRSEM image. When excited at 700 nm, NCLZH exhibit high NIR emission at 768 nm, suggesting that it could be a viable substitute for contact-free bioimaging in healthcare. Furthermore, addition of NCDs to LZH enhanced the anticancer activity of NCLZH with IC₅₀ 75 µg/mL, and cytotoxicity studies of NCLZH show 92% cell viability towards adult dermal fibroblast cell lines which confirms NCLZH as Photodamage-Free Bioimaging Tool. Hence, NCLZH can function in future as an efficient fluorescent probe in real-time fluorescence-guided surgery for cancer diagnosis and treatment which is a potential extension of the current work in future.

Graphical abstract