Development of smart devices based on polymeric fibers and NIR-responsive nanoparticles for drug delivery

The administration of an active pharmaceutical ingredient to achieve a therapeutic effect can be obtained through various routes and in different forms, which aim to target the specific pathology of interest. The necessity for enhancing drug efficacy and improvement for patient’s therapy has led to the development of drug delivery systems (DDSs) that enable targeted delivery with controlled drug release by incorporating the drug within a polymeric matrix. Fabrication of a DDS with controlled and sustained release benefits the patient from the need for repeated injections or the toxicity caused by regular consumption of tablets, as both drug formulations cannot provide the delivery of a high and constant dose over time. However, conventional DDSs work through a passive release, in which the dose, once designed, cannot be further enhanced. This study focuses on the development of a stimuli-responsive DDS, aimed at offering an on-demand actionable drug release with the irradiation of a near-infrared (NIR) light. The idea behind such a smart DDS relies on the capacity of some materials to respond to NIR irradiation due to plasmonic resonance effect and increase their temperature locally, whereas NIR light is highly penetrating in the human body with no harmful effects on the cells. This strategy ensures a highly specific response of the DDS system, since the local increase of temperature above 37°C can enhance the diffusion phenomena and allow a dose higher than the passive release to be delivered at selected time intervals. To this purpose, Indium Tin Oxide (ITO) nanoparticles were synthesized in the laboratory, as NIR-responsive materials, and characterized. Polyvinyl alcohol (PVA), a hydrophilic non-biodegradable polymer, was thus employed as a polymer matrix. Using the electrospinning technique, PVA ultrafine fibers incorporated with ITO nanoparticles were produced and crosslinked via freeze-drying prior to investigate the photothermal response of different concentrations of ITO (0 % to 4 % w/w) with a specific exposure time and at a selected NIR light distance. Using gelatin as a model molecule, mixed within the PVA/ITO suspension (at 5 % and 10 % w/w) before the electrospinning process, a DDS prototype was obtained. Thereafter, the release profiles of gelatin were studied, and an irradiating protocol was assessed, which preliminarily disclosed the possibility of tuning gelatin release by actioning the DDS with NIR light. The insights gained from this study aid in the development of smart DDS based on these materials. Further biological investigations on its therapeutic effects and regulatory standards are necessary for the development of a smart drug delivery system that can facilitate patients in achieving an externally controlled and prolonged DDS, which could be useful for resistant infection and cancer treatments, among others.