(178c) Exploiting Oxygen Inhibited Photopolymerization to Control Shape, Size and Network Architecture of Functional Hydrogels As a Biosensing Platform

Hydrogel microparticle and nanoparticle-based hydrogel biosensing platforms require delicate control over network architecture and the conjugation of biofunctional groups, which impacts their mechanical properties and molecular permeability and diffusivity. For most hydrogel particle fabrication methods that rely on photoinitiated chain polymerization, the impact of exposure conditions and photopolymerization kinetics on the resulting particle properties is not well described. In this talk I will introduce oxygen inhibited photopolymerization within emulsion droplets as a high throughput technique for the controlled production of hydrogel particles. Empirical data, coupled with a detailed reaction-diffusion analysis, reveals that this technique can be used to exquisitely manipulate particle size, shape, and hydrogel particle properties. Different assays were conducted to examine the network properties of these particles, demonstrating a high degree of structural tunability, which, in turn, governs compound encapsulation and diffusion profile, as well as the presence of radial crosslinking gradients that regulate the availability of functional groups (Figure 1). A detailed quantitative description of the photopolymerization process using a reaction-diffusion model presents the ability to accurately predict and optimize hydrogel network properties to produce tailored hydrogel microparticles for targeted applications.

Figure 1: Oxygen-inhibited photopolymerization of droplets containing acrylate-PEG-biotin produces functional hydrogels with surfactant free surfaces. A. Schematic illustration of the fabrication of hydrogel microparticles. B. Pictograph of the process described in A, with Na-Rh fluorescence imaging showing the presence of crosslinking gradient in the radial direction.