This study explores the intriguing modulations in the excitation wavelength dependence of carbon dot photoluminescence (PL), induced by the solvent medium. Our results indicate that different emissive states of carbon dots are stabilized to different extents by the surrounding solvent environment. Consequently, in some solvents, such as ethyl acetate and acetonitrile, the PL of the carbon dots is strongly dependent on the excitation wavelength, while in other solvents, like water, the PL of the same carbon dot becomes independent of the excitation wavelength. These observations contribute to the enhancement of our understanding of the photophysics and PL mechanisms of this important class of luminescent materials, especially to discriminate between the PL arising from the “molecular state” and the “surface state”.

Magnetic drug targeting is a drug delivery system that can be used in loco-regional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by co-precipitation of iron oxide followed by coating with polyvinyl pyrrolidone (PVP). Characterization was performed using X-ray diffraction, TEM, TGA, FTIR and UV-Vis Spectroscopy. Magnetite (Fe₃O₄) remained as the core of the carrier. The amount of PVP bound to the iron oxide nanoparticles was estimated by thermogravimetric analysis (TGA) and the attachment of PVP to the iron oxide nanoparticles confirmed by FTIR analysis. The loading efficiency of Epirubicin hydrochloride onto the PVP coated and uncoated iron oxide nanoparticles was measured at intervals such as 1 hr and 24 hrs by UV-Vis Spectroscopy. The binding of Epirubicin hydrochloride to the PVP coated and uncoated iron oxide nanoparticles were confirmed by FTIR analysis. The present findings showed that Epirubicin hydrochloride loaded PVP coated iron oxide nanoparticles are promising for magnetically targeted drug delivery. The drug displayed increased cell cytotoxicity at lower concentrations when conjugated with the nanoparticles than being administered conventionally as individual drugs.