Flexible Delivery Patch Systems based on Thermoresponsive Hydrogels and Submicronic Fiber Heaters

Abstract

This paper proposes a novel, flexible, low cost administration patch which could be used as a non-invasive, controlled transdermal drug delivery system. The fabricated device consists in a flexible microfiber architecture heater covered with a thermoresponsive hydrogel, namely poly(N-isopropylacrylamide), as a matrix for the incorporation of active molecules. The manufacturing process consists of two main steps. First, the electrospun poly(methyl methacrylate) fiber networks are sputter coated with a thin gold layer and attached to flexible poly(ethylene terephthalate) substrates to obtain the heating platforms. Second, the heaters are encapsulated in poly(ethylene terephthalate) foils and covered with poly(N-isopropylacrylamide) hydrogel sheets. In order to illustrate the functionality of the fabricated patch, the hydrogel layer is loaded with methylene blue aqueous solution and is afterwards heated via Joule effect, by applying a voltage on the metalized fibers. The methylene blue releasing profiles of the heated patch are compared with those of the unheated one and the influence of parameters such as hydrogel composition and morphology, as well as the applied voltage values for microheating are investigated. The results indicate that the fabricated patch can be used as a drug administration instrument, while its performance can be tuned depending on the targeted application.

On the swelling behavior of poly(N‐Isopropylacrylamide) hydrogels exposed to perfluoroalkyl acids

“…Additional absorption at 1173 and 1130 cm −1 points to CH 3 vibrations. Higher energy peaks at 3426, 3310, and 3059 cm −1 mark NH stretching while those at 2970, 2936, and 2874 cm −1 represent CH asymmetric and symmetric stretching 51 . Notably, the CHCH 2 stretching, twisting, and wagging peaks at 1620, 988, and 964 cm −1 for NIPAM and 1624, 991, and 964 cm −1 for MBA, respectively, are absent from the polymer's spectrum 52 .…”

Hydrogel design strategies for drug delivery

“…Typically, thermogels rely on the existence of a phasetransition between room temperature and physiological temperature, e.g. a lower critical solution temperature (LCST), such as poly(N-isopropylacrylamide) (PNIPAM) or poly(oligoethylene glycol methacrylate) (POEGMA), or a volume phase transition temperature (VPTT) (45). This transition is usually actuated by the change in temperature occurring from contact of the material with the body, e.g.…”

“…Focusing on the role of chirality to design thermogelling polymers, Mao et al (53) explored the stereocomplexation of complementary chiral blocks, with constructs based on an enantiomeric mixture of poly(D-lactic acid((PDLA)/PEG diblock and poly(L-lactic acid(PLLA))/PEG; the polymers exhibited multiple gel-sol-gel transitions upon heating, which were rationalised by small-and wideangle X-ray scattering, and used to tune the release of the cancer drug doxorubicin (DOX). Using heat-induced phase transition as the response of another trigger, a flexible patch for transdermal delivery was developed by Evanghelidis et al, combining PNIPAM with a microstructured heater based on an electrospun polymer fiber network covered with a thin gold layer and attached to flexible PET substrates (45). When submitted to a 3V current, the patch heated up and released a model drug from the gel matrix.…”

Stimuli-Responsive Hydrogels for Local Post-Surgical Drug Delivery

“…A PNIPAAm-derived hydrogel was also used to fabricate dermal patches to generate a controlled transdermal drug delivery system. It was shown that the proposed multi-layer patch, including a microfiber heater and drug eluted hydrogel, could be used as a wearable wound care system, suitable for gastric and hepatic injuries [84].…”