Thermal Response of Gold Nanorods-loaded Polymeric Hydrogels Under NIR Laser Exposure for Biomedical Applications

This work presents the synthesis and characterization of gold nanorods (GNRs)-loaded agarose-carbomer-hyaluronic acid (AC-HA) hydrogels intended for biomedical applications, such as drug delivery and tissue engineering. The GNRs were synthesized by adopting a facile route and characterized in terms of absorption spectrum and size. The AC-HA hydrogels were attained through a microwave-assisted polycondensation reaction and loaded with GNRs. The hydrogels showcased stable support for GNRs, integrated within the three-dimensional polymeric network. A particular focus was then dedicated to the characterization of the thermal response of the hydrogels under near-infrared laser exposure, using Fiber Bragg grating (FBG) sensors. FBG sensors allowed for the accurate detection of the maximum temperature variation (∆T) and reconstruction of high-spatially resolved thermal maps within the irradiated samples. The presence of GNRs was found to enhance the photothermal performances of the hydrogels: at the end of laser exposure, GNRs-loaded hydrogels were characterized by a mean ∆T of 31.5 ± 4.1 °C (i.e., 4-fold increment in ∆T compared to control samples). Overall, this study sets the basis for the characterization of light-responsive composite materials to be used as photothermal treatment agents. Besides, the results encourage further investigations on the laser-induced thermal response of nanoparticles-loaded polymeric hydrogels to serve as smart systems for biomedical purposes.Clinical Relevance–This work establishes light-responsive nanoparticles-loaded hydrogels as promising smart systems for therapeutic purposes and highlights the importance of accurately characterizing their photothermal response.