A new paradigm in biosensing: MOF-carbon dot conjugates

Metal-organic frameworks (MOFs) have emerged as promising nanocarriers for targeted drug delivery, owing to their unique structural properties and tunable pore sizes. Integrating carbon dots (C-dots) into MOFs will further enhance their functionality and imaging capabilities. In this study, the synthesis and characterization of C-dots loaded MOF is detailed as a novel pH and temperature-responsive nanoplatform for the imaging and therapy of neuroblastoma. The C-dots were synthesized using a modified microwave method, and their structural and optical properties were characterized using techniques such as XRD, FTIR, and XPS. The C-dots demonstrated a hexagonal graphite structure with hydroxyl and carboxyl surface functional groups. The C-dots also exhibited green emission under excitation at 405 nm with concentration-dependent emission behaviour. The pH-dependent emission studies reveal a gradual increase in fluorescence intensity from pH 3–9, followed by a rapid decrease at higher pH values. It is observed that the fluorescence intensity decreased by ∼50% upon increasing the temperature (30–65 °C) at a step of 5 °C covering the range of physiological temperature. The photothermal studies elucidated that the C-dots exhibit good photothermal conversion properties upon NIR laser irradiation that can find applications in the areas like photothermal therapy. The drug release studies confirmed the pH-responsive drug release property of the nanocomposite. Further, the surface-modified nanocomposite was efficiently uptaken by the neuroblastoma cells suggesting the possibility of targeted therapy for cancer. Overall, this study gives new insights into the synthesis, characterisation, and functionalization of C-dots loaded with ZIF-8 NPs, revealing their potential for drug delivery applications.