Multi-Compartmental Hydrogel Microparticles Fabricated by Combination of Sequential Electrospinning and Photopatterning.

Multi-compartmental non-spherical hydrogel microparticles were fabricated by combining electrospinning and photopatterning. Sequential electrospinning produced multi-layered fiber matrices with different composition in which each layer became a compartment of the particle. Photopatterning of the hydrogel in the presence of the multi-layered fiber matrix generated multi-compartmental microparticles with different vertical functionalities. While the shapes of the hydrogel microparticles were determined by the design of the photomask, the chemical properties and size of each compartment were independently controlled by changing the molecules incorporated into each fiber matrix and the electrospinning times, respectively. The resultant multi-compartmental hydrogel microparticles could carry out not only the release of different growth factors with independent kinetics but also binding of multiple targets at different compartments.

Removal of Methyl Red from Aqueous Solution Using Polyethyleneimine Crosslinked Alginate Beads with Waste Foundry Dust as a Magnetic Material.

In this study, a cost-effective adsorbent based on sodium alginate (SA) with waste foundry dust (WFD) was fabricated for the removal of methyl red (MR) from aqueous media. However, the utilization of WFD/SA beads to remove anionic dyes (such as MR) from effluents has limitations associated with their functional groups. To improve the adsorption performance, WFD/SA-polyethyleneimine (PEI) beads were formed via PEI crosslinking onto WFD/SA beads, which could be attributed to the formation of amide bonds from the carboxyl and amino groups due to the change of N-H bonds in the reaction. The Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) results indicated that PEI was crosslinked on the WFD/SA via a chemical reaction. In the FTIR spectra of WFD/SA-PEI, peaks of the -COO (asymmetric) stretching vibration shifted to 1598 and 1395 cm-1, which could be attributed to the hydrogen-bonding effect of the N-H groups in PEI. In the N1s spectrum, three deconvoluted peaks were assigned to N in -N= (398.2 eV), -NH/-NH2 (399.6 eV), and NO2 (405.2 eV). WFD/SA-PEI beads were assessed and optimized for aqueous MR adsorption. The WFD/SA-PEI beads showed a high removal efficiency for MR (89.1%) at an initial concentration of 1000 mg/L, and presented a maximum MR adsorption capacity of 672.7 mg/g MR. The adsorption process showed a good fit with the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model. The amino and hydroxyl groups in the WFD/SA-PEI beads facilitate strong hydrogen bonding and electrostatic interactions. Moreover, these WFD/SA-PEI beads were easily recovered after the adsorption process.

Thermoresponsive poly(N-isopropylacrylamide) hydrogel substrates micropatterned with poly(ethylene glycol) hydrogel for adipose mesenchymal stem cell spheroid formation and retrieval.

Cell spheroid formation is necessary to develop three-dimensional (3D) cellular environments that provide appropriate cell-cell and cell-matrix interactions similar to in vivo environments without additional substrates. Although some methods including stirring culture, low adhesion plate culture, hanging drop, and microfluidics are used to construct cell spheroids, there is no method to fulfill all of the mass production of uniform spheroids, simple media change, and easy retrievability. Here, bulk poly(N-isopropylacrylamide) (PNIPAAm) hydrogel substrate (PHS) was used to fabricate, culture, and retrieve cell spheroids. Adipose-derived stem cells (ASCs) were cultured on bulk PHS to form spheroids. ASCs formed cell spheroids directly on substrates without additional manipulation. These spheroids adhered to the semi-adhesive substrate, while the spheroids fabricated using the nonadhesive surface method floated without getting fixed to the surface. Bulk PHS stiffness was evaluated using the compressive test (compressive modulus: 153 ± 11 kPa). A poly(ethylene glycol) (PEG) hydrogel microwell pattern was created on PHS to control the spheroid size, forming uniform ASC spheroids between 100 and 150 µm in diameter on 200 and 300 µm well-patterned substrates. Cell-cell interactions in the resulting ASC spheroids were evaluated based on fibronectin and laminin expression; fluorescence intensities of fibronectin- and laminin-immunostained images of ASC spheroids were 10.9 and 7.3 times higher than those of ASCs cultured on the tissue culture plate, respectively. ASC spheroids were detached following incubation at 4 °C for 10 min (retrieval efficiency: 74 ± 19%). Retrieved spheroid cell viability was over 97.5%. The PEG hydrogel microwell-patterned PHS is a convenient spheroid fabrication and retrieval platform that can increase cell spheroid usage.

Hydrophilic surface modification of poly(methyl methacrylate)-based ocular prostheses using poly(ethylene glycol) grafting.

Ocular prostheses are custom-made polymeric inserts that can be placed in anophthalmic sockets for cosmetic rehabilitation. Prosthetic eye wearers have reduced tear amount, and they often experience dry eye symptoms including dryness, irritation, discomfort, and discharge. Most modern ocular prostheses are made of poly(methyl methacrylate) (PMMA), which is highly hydrophobic. Previous research has shown that improving the wettability of contact lens materials decreases its wearers discomfort by increasing lubrication. Therefore, hydrophilic modification of PMMA-based ocular prostheses might also improve patient discomfort by improving lubrication. We modified the surfaces of PMMA-based ocular prostheses using poly(ethylene glycol) (PEG), which is hydrophilic. To do this, we used two strategies. One was a "grafting from" method, whereby PEG was polymerized from the PMMA surface. The other was a "grafting to" method, which involved PEG being covalently bonded to an amine-functionalized PMMA surface. Assessments involving the water contact angle, ellipsometry, and X-ray photoelectron spectroscopy indicated that PEG was successfully introduced to the PMMA surfaces using both strategies. Scanning electron microscopy and atomic force microscopy images revealed that neither strategy caused clinically significant alterations in the PMMA surface morphology. In vitro bacterial adhesion assessments showed that the hydrophilic modifications effectively reduced bacterial adhesion without inducing cytotoxicity. These results imply that hydrophilic surface modifications of conventional ocular prostheses may decrease patient discomfort and ocular prosthesis-related infections.