Laser light triggered smart release of silibinin from a PEGylated-PLGA gold nanocomposite

In this work a new remotely-triggered drug delivery system based on PEG-PLGA_Au nanocomposite is proposed. Due to the optical properties of gold nanoparticles (Au NPs), the nanovector allows on-demand control of the dose, the timing and the duration of the drug release, upon irradiation with red laser light. The Au NPs are synthesized by laser ablation and subsequently embedded into the PEG-PLGA copolymer via a modified emulsion-diffusion method, devised in such a way that both Au NPs and silibinin (SLB), a flavonolignan with promising anti-neoplastic effects, can be co-loaded into the polymeric system in a single step procedure. A combination of analytical techniques including nuclear magnetic resonance (NMR), static and dynamic light scattering (SLS, DLS), gel permeation chromatography (GPC), thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), infrared (FTIR) spectroscopy and scanning/transmission electron microscopies (SEM/STEM/TEM), have been used to study the structural and morphological properties of the nanocomposite. The loading efficiency and the drug content, evaluated by UV-vis absorption optical spectroscopy, are 89% and 8.8%, respectively. Upon laser irradiation the system releases the encapsulated drug with a higher efficiency (similar to 10%) than that without irradiation. This behaviour indicates that our nanoplatform is responsive to light and it could be considered a promising new type of light-activated drug delivery carrier applicable to the biomedical field.