Poly(2‐hydroxyethyl methacrylate) hydrogel: from a brittle material to a nanofilled semi‐interpenetrating polymer network with potential application in wound dressings

Poly(N-vinylcaprolactam)-Gold Nanorods-5 Fluorouracil Hydrogels: In the Quest of a Material for Topical Therapies against Melanoma Skin Cancer

Chemically crosslinked hydrogels based on poly(N-vinylcaprolactam) (PNVCL) were synthetized by a photoinitiated chemical method. A galactose-based monomer, 2-lactobionamidoethyl methacrylate (LAMA), and N-vinylpyrrolidone (NVP) were added with the aim to improve the physical and chemical properties of hydrogels. The effects of both comonomers on the swelling ratio (Q), volume phase transition temperature (VPTT), glass transition temperature (T_g), and Young's moduli by mechanical compression below and above the VPTT were studied. Gold nanorods (GNRDs) and 5-fluorouracil (5FU) were embedded into the hydrogels, to study the drug release profiles with and without the excitation of GNRDs by irradiation in the near-infrared region (NIR). Results showed that the addition of LAMA and NVP increased the hydrogels' hydrophilicity, elasticity, and VPTT. The loading of GNRDs in the hydrogels changed the release rate of 5FU when irradiated intermittently with an NIR laser. The present study reports on the preparation of a hydrogel-based platform of PNVCL-GNRDs-5FU as a potential hybrid anticancer hydrogel for chemo/photothermal therapy that could be applied against skin cancer for topical 5FU delivery.

Toughened Hydrogels for 3D Printing of Soft Auxetic Structures

Materials with negative Poisson's ratio have attracted considerable attention and offered high potential applications as biomedical devices due to their ability to expand in every direction when stretched. Although negative Poisson's ratio has been obtained in various base materials such as metals and polymers, there are very limited works on hydrogels due to their intrinsic brittleness. Herein, we report the use of methacrylated cellulose nanocrystals (CNCMAs) as a macro-cross-linking agent in poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels for 3D printing of auxetic structures. Our developed CNCMA-pHEMA hydrogels exhibit significant improvements in mechanical properties, which is attributed to the coexistence of multiple chemical and physical interactions between the pHEMA and CNCMAs. Structures printed by using CNCMA-pHEMA hydrogels show auxetic behavior with greatly enhanced toughness and stretchability compared to the hydrogel with a traditional cross-linking agent. Such strong and tough auxetic hydrogels would contribute toward establishing advanced flexible implantable devices such as biodegradable oesophageal self-expandable stents.