Effect of network mesh size and swelling to the drug delivery from pH responsive hydrogels

Abstract

pH responsive hydrogels are ideal platforms for numerous therapeutic delivery applications, including oral delivery, as they are capable of overcoming the many barriers that must be considered when creating an effective drug delivery system. Understanding of the innate hydrogel network structure and its swelling behavior at environmentally relevant conditions is vital for designing hydrogel network capable of effective controlled drug release. Herein, we explored how to expand traditional techniques of swelling and pore characterization to gain better insight into the performance of anionic microparticles composed of the poly(methyl methacrylate‐co‐acrylic acid) with varying molar percentage of 10, 20, and 30 mol% of MMA, for controlled release of low‐molecular‐weight drugs. By evaluating these carrier systems at environmental conditions, we can observe changes in swelling and pore size of the anionic hydrogel networks as a function of MMA, which was then correlated with the release profiles of the small‐molecular‐weight drug sodium nitrate. With the correlation of the swelling behavior of the networks and the release profiles, we demonstrated how the expansion of swelling parameters at relevant pH values provides further incite for evaluating for the optimal blend for controlled release. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48767.

Solute Transport Dependence on 3D Geometry of Hydrogel Networks

“…Schematic representations for swollen polymer networks, also known as hydrogels, frequently oversimplify the structure. The most commonly used and symbolic schematic for a swollen polymer network has four polymer chains in an overlapping hash pattern, [ 1–4 ] implying that the network junctions are tetrafunctional and all chains are restricted to a 2D plane. In those representations, the network appears to form a square portal that a solute could pass through if its diameter was less than the length of one network chain between two junctions ( Figure A).…”

High-Throughput FRAP Analysis of Solute Diffusion in Hydrogels

“…As with solutes, analysis of how hydrogel properties affect solute diffusivity in hydrogels has focused on the relative sizes of molecular components. ,,,, Mesh size, which describes the average distance between two network junctions connected by a polymer chain, has been frequently associated with solute diffusivities in hydrogels via convenient, often simplified, correlations or scaling concepts. We recently suggested that the term “mesh radius,” which describes the expected radius of a hydrodynamically spherical solute that would pass through a hydrogel network portal, would be a more accurate predictor of solute diffusivity than mesh size .…”

Controlled Drug Release by the Pore Structure in Polydimethylsiloxane Transdermal Patches

“…Maximizing the permeability for water with retained mechanical durability is usually the goal in development of fast disintegrating tablets or extended-release coated tablets [12][13][14]. More sophisticated control of the drug release is usually expected for microspheres, implants or hydrogels, where swelling additionally contributes to the diffusion mechanism [15][16][17]. Although the approach of matrix modification with solid or liquid hydrophilic excipients to increase water transport or drug release was reported by other authors [18,19], the pore formation in PDMS materials suitable for transdermal drug delivery has been an unexplored topic.…”