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

Abstract

In this work we report the photopolymerization of poly(2-hydroxyethyl methacrylate) (PHEMA) together with a hydrophilic chitosan derivate (carboxymethyl-chitosan) to yield a semi-interpenetrating polymer network (semi-IPN) that was filled with poly(N-vinylcaprolactam)/poly(ethylene glycol methacrylate) core-shell nanogels in order to enhance the mechanical properties of the resulting hydrogels. The mechanical properties of the nanofilled semi-IPNs were found to be more suitable for wound dressing applications than the PHEMA hydrogel as described by dynamic mechanical analysis in dry form and submerged in water. This was evidenced by a higher Young's modulus and higher elongation at break in the semi-IPNs compared to blank PHEMA hydrogels. Furthermore, when the hydrogels were filled with nanogels, there was an elongation at break similar to that of skin with only a slightly lower Young's modulus.

Semi‐Interpenetrated Polymer Networks Based on PHEMA and Modified Chitosan as a Potential Bactericide Hydrogel for Wound‐Healing

“…This behavior is attributed to the incorporation of CMCS, which adds hydrophilic groups into the semi‐IPNs, reduces the rigidity of the PHEMA network and increases the network defects. [ 12 ] These values show the crosslink density decreases and the molecular weight between crosslinks increases when the CMCS is incorporated into the PHEMA network, being slightly lower for HC‐L2 compared to HC‐H2. This can be observed due to CMCS chains hinder the radical crosslinking of PHEMA growing chains so, the higher molecular weight for CMCS, the lower the crosslinking density between the growing PHEMA chains, increasing the molecular weight between crosslink points.…”

“…In a first stage, low (L) and high (H) molecular weight chitosan was modified to carboxymethyl‐chitosan, in order to improve their solubility in water at neutral pH, according to the literature. [ 12 ] Then, the synthesis of HC‐IPNs was carried out ( Figure ). As an example, the following methodology describes the preparation of a semi‐IPN with 2 wt% CMCS of high molecular weight (H‐CMCS) in relation to HEMA (hydrogel HC‐H2).…”

“…[11] The combination of PHEMA and a chitosan derivative in a hydrogel has been reported previously by our group resulting in hydrogels with improved mechanical properties. [12] In this work, the preparation of semi interpenetrating polymer networks (semi-IPNs) based on PHEMA hydrogels and carboxymethyl chitosan (CMCS) via photopolymerization are reported. For this, low and high molecular weight chitosan were modified to a more hydrophilic form, such as CMCS.…”

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

“…where F is the fractional drug release, M t is the mass of drug at time t, M 0 is the initial mass of drug in the solution, k is the release rate constant for different equations, and n is the diffusional exponent. The 5FU release kinetics were studied through different mathematical models (Equations (5) to (8)). Zero-order, first-order, Higuchi, and Peppas models were employed [33].…”

“…Hydrogels have been widely used as wound dressings due their ability to incorporate a large volume of water into their structure, behaving more similarly to living tissue than any other synthetic material. Additionally, through control over its physicochemical properties, it is possible to significantly influence its drug loading and release capacity, and in vitro and in vivo stability [8]. In particular, temperature-responsive hydrogels have been extensively studied for biomedical and pharmacological applications, mainly because they can reversibly change from a swollen to a shrunken state at a specific temperature, known as the volume phase transition temperature (VPTT).…”