Homo- and Copolymer Hydrogels Based on N-Vinylformamide: An Investigation of the Impact of Water Structure on Controlled Release

Abstract

This study investigated the performance of novel hydrogels based on poly (N-vinylformamide) (PNVF), copolymers of NVF with N-hydroxyethyl acrylamide (HEA) (P(NVF-co-HEA)), and 2-carboxyethyl acrylate (CEA) (P(NVF-co-CEA)), which were synthesized by photopolymerization using a UVLED light source. The hydrogels were analyzed for important properties such as equilibrium water content (%EWC), contact angle, freezing and non-freezing water, and diffusion-based in vitro release. The results showed that PNVF had an extremely high %EWC of 94.57%, while a decreasing NVF content in the copolymer hydrogels led to a decrease in water content with a linear relationship with HEA or CEA content. Water structuring in the hydrogels showed appreciably more variance, with ratios of free to bound water differing from 16.7:1 (NVF) to 1.3:1 (CEA), corresponding to PNVF having ~67 water molecules per repeat unit. The release studies of different dye molecules followed Higuchi’s model, with the amount of dye released from the hydrogels depending on the amount of free water and the structural interactions between the polymer and the molecule being released. The results suggest that PNVF copolymer hydrogels have potential for controlled drug delivery by altering the polymer composition to govern the amount and ratio of free to bound water contained in the hydrogels.

Water-soluble macromers based on 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (Na-AMPS) for rapid in situ hydrogel film formation

“…9(c)); this is consistent with the homopolymers of CEA having been shown to have a contact angle of ∼75° 25. Fig.…”

“…9(c)); this is consistent with the homopolymers of CEA having been shown to have a contact angle of ∼75°. 25 Fig. 9(d) shows the PACM-AGE against a conventional AMPS-based hydrogel; the AMPS hydrogel contains only AMPS and thus gives a lower angle (21.2° vs. 58.2°).…”

“…It has been demonstrated to alter the rheological attributes of ceramic suspensions and reduce the adverse impacts of oxygen inhibition. 25 In this study, the molar fraction ratio of AMPS to an acid-containing monomer is set at 1 : 0.8, a proportion similar to that utilized by Nesic et al 26 Their research indicated that MAA/AMPS ratios ranging from 50 : 50 to 25 : 75 yielded optimal mechanical properties. This research intends to mitigate toxicity from unpolymerized monomers in hydrogel formation, focusing on macromer technology.…”

Development of Natural Active Agent-Containing Porous Hydrogel Sheets with High Water Content for Wound Dressings

“…Hydrogels are chemically or physically cross-linked hydrophilic polymer networks that are able to absorb and retain a large amount of water or biological fluids. They are often used in tissue engineering [ 1 ], drug delivery [ 2 , 3 , 4 ], and biomedical devices (e.g., wound dressings and contact lenses) [ 5 , 6 ] due to their biomimetic properties and high water content. Hydrogel wound dressings are important medical devices that can be used for a wide range of wounds such as shallow and deep open wounds (pressure sores, leg ulcers, surgical and malignant wounds, partial thickness burns, scalds, and lacerations) that may be located on hard-to-fit locations on the body (such as joints, hands, and face) [ 7 , 8 ].…”