Biocompatible silver nanoparticles embedded in a PEG-PLA polymeric matrix for stimulated laser light drug release

The laser-induced release of a well-known hepatoprotective drug (silibinin, SLB) from a temperature-sensitive polymeric composite loaded with silver nanoparticles (Ag NPs) was investigated. The surface chemistry tuning and the specific design of Ag NPs is fundamental in view of the engineering of specific stimuli-responsive systems, able to control drug release in response to external stimuli. The release profiles of SLB from the newly synthesized PEGPLA@ Ag composite show strong dependences on laser wavelength and Ag NPs Surface Plasmon Resonance (SPR). The resonant laser light excites the SPR of the NPs and the absorbed energy is converted into heat due to electronphoton collisions. The heating generated from the nanometer-sized metal particles embedded within the polymer is efficient and strongly localized. The nanovector, irradiated by a relatively low intensity laser but tuned specifically to the metal NPs SPR, releases the encapsulated drug with a higher efficiency than that not irradiated or irradiated with a laser wavelength far from the metal SPR. A combination of analytical techniques including UV-Vis, NMR and FTIR spectroscopy, Scanning/Transmission Electron Microscopy (SEM/STEM/TEM) has been used to study the structural and morphological properties of the composite. The controllable specificity of this approach and the possibility of the SPR-mediated localized photo-thermal effect to be usefully applied in aqueous environments are the relevant advances of the proposed system for photothermal therapies that make use of visible optical radiation or for the drug delivery in proximity of the tumor cells.