Search Results (2)

The swelling-regulated transport properties of modified and cross-linked HPC-based hydrogel formulations containing NaCMC and citric acid were studied as stimuli-responsive polymeric membranes under various conditions, including deionized water. Physiological conditions were simulated by evaluating various pH conditions (1.2, 6.8, and 7.4). The pseudo-second-order kinetic model best described the swelling process, suggesting that both solvent uptake capacity and polymer network relaxation contribute to the extent of swelling. The swelling behavior of the hydrogel formulations was significantly influenced by salt concentration. The modified HPC hydrogel system exhibited stimuli-responsive swelling–switching behavior under saline, water/ethanol, and acidic/basic environments, demonstrating reversible swelling–deswelling cycles. Maximum swelling was observed in water at pH 7.4. In contrast, abrupt deswelling in an ethanol solution at pH 1.2 reduced hydrogel swelling and water uptake. The effect of temperature on the swelling behavior of the hydrogel and its thermo-responsive swelling behavior was also evaluated. Drug release behavior suggested diffusion-mediated release through the swelling hydrogel matrix. These findings suggest that the modified HPC-based hydrogel system may be useful for pH-responsive oral drug delivery applications. Full article

To bring to bear the power of centrifugal microfluidics on vertical flow immunoassays, control of flow orthogonally through nanoporous membranes is essential. The on-disc approach described here leverages the rapid print-cut-laminate (PCL) disc fabrication and prototyping method to create a permanent seal between disc materials and embedded nanoporous membranes. Rotational forces drive fluid flow, replacing capillary action, and complex pneumatic pumping systems. Adjacent microfluidic features form a flow path that directs fluid orthogonally (vertically) through these embedded membranes during assay execution. This method for membrane incorporation circumvents the need for solvents (e.g., acetone) to create the membrane-disc bond and sidesteps issues related to undesirable bypass flow. In other recently published work, we described an orthogonal flow (OF) platform that exploited embedded membranes for automation of enzyme-linked immunosorbent assays (ELISAs). Here, we more fully characterize flow patterns and cellulosic membrane behavior within the centrifugal orthogonal flow (cOF) format. Specifically, high-speed videography studies demonstrate that sample volume, membrane pore size, and ionic composition of the sample matrix significantly impact membrane behavior, and consequently fluid drainage profiles, especially when cellulosic membranes are used. Finally, prototype discs are used to demonstrate proof-of-principle for sandwich-type antigen capture and immunodetection within the cOF system. Full article