Carbon-based Thermoresponsive Core-Shell Nanocomposites for Controlled Drug Delivery

This study explores the design and synthesis of an innovative thermoresponsive nanocomposite for applications in drug delivery and controlled release. The nanocomposite core consists of carbon dots (CDs), enveloped by functionalized agarose units tethered to poly(N-isopropylacrylamide) (PNM), a thermoresponsive polymer with a lower critical solution temperature (LCST) of about 32 °C. Irradiation at 405 nm induces localized heating within the CDs core transmitting heat to the PNM shell via agarose linkages, modulating the LCST to approach the physiological range, ideal for biological therapies. The CDs-agar-PNM nanostructure is confirmed by ATR-FTIR spectroscopy. Dynamic light scattering (DLS) analysis, indicated a coil-to-globule transition of the PNM completed at temperatures above 34 °C. UV-vis spectroscopy confirmed efficient loading and release of curcumin below and above the LCST, respectively. Molecular dynamics simulations (MD) demonstrated that evolution of the radius of gyration of PNM and intermolecular hydrogen bond analysis between the polymer and agarose, resulted in an increase of LCST, depending on the length of PNM. This is the first case reported in the literature that documents an increase in the transition temperature of PNM without making chemical modifications to its structure, such as copolymerization or adding functional groups.