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166 results on '"Alge, Daniel L."'

12. Enzyme‐functionalized alginate microparticles enable anaerobic culture under ambient oxygen.

Author

Williams, Tyrell J., Daboin, Claudia, Kim, Paul, Guo, Fengguang, de Figueiredo, Paul, and Alge, Daniel L.

Abstract

Methods for culturing oxygen‐sensitive cells and organisms under anaerobic conditions are vital to biotechnology research. Here, we report a biomaterial‐based platform for anaerobic culture that consists of glucose oxidase (GOX) functionalized alginate microparticles (ALG‐GOX), which are designed to deplete dissolved [O2] through enzymatic activity. ALG‐GOX microparticles were synthesized via a water‐in‐oil emulsion and had a size of 132.0 ± 51.4 µm. Despite having a low storage modulus, the microparticles remained stable under aqueous conditions due to covalent crosslinking through amide bonds. Enzyme activity was tunable based on the loaded GOX concentration, with a maximum activity of 3.6 ± 0.3 units/mg of microparticles being achieved at an initial loading concentration of 5 mg/mL of GOX in alginate precursor solution. High enzyme activity in ALG‐GOX microparticles resulted in rapid oxygen depletion, producing a suitable environment for anaerobic culture. Microparticles loaded with both GOX and catalase (ALG‐GOX‐CAT) to reduce H2O2 buildup exhibited sustained activity for potential long‐term anaerobic culture. ALG‐GOX‐CAT microparticles were highly effective for the anaerobic culture of Bacteroides thetaiotaomicron, with 10 mg/mL of ALG‐GOX‐CAT microparticles supporting the same level of growth in an aerobic environment compared to an anaerobic chamber after 16 h (8.70 ± 0.96 and 10.03 ± 1.03 million CFU, respectively; N.S. p = 0.07). These microparticles could be a valuable tool for research and development in biotechnology. [ABSTRACT FROM AUTHOR]

Published
2024
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33. Creating Physicochemical Gradients in Modular Microporous Annealed Particle Hydrogels via a Microfluidic Method.

Author

Xin, Shangjing, Dai, Jing, Gregory, Carl A., Han, Arum, and Alge, Daniel L.

Subjects
HYDROGELS, HUMAN stem cells, MESENCHYMAL stem cells, MICROGELS, ETHYLENE glycol, PARTICLES
Abstract

Microporous annealed particle (MAP) hydrogels are an attractive platform for engineering biomaterials with controlled heterogeneity. Here, a microfluidic method is introduced to create physicochemical gradients within poly(ethylene glycol) based MAP hydrogels. By combining microfluidic mixing and droplet generator modules, microgels with varying properties are produced by adjusting the relative flow rates between two precursor solutions and collected layer‐by‐layer in a syringe. Subsequently, the microgels are injected out of the syringe and then annealed with thiol‐ene click chemistry. Fluorescence intensity measurements of constructs annealed in vitro and after mock implantation into a tissue defect show that a continuous gradient profile is achieved and maintained after injection, indicating utility for in situ hydrogel formation. The effects of physicochemical property gradients on human mesenchymal stem cells (hMSCs) are also studied. Microgel stiffness is studied first, and the hMSCs exhibit increased spreading and proliferation as stiffness increased along the gradient. Microgel degradability is also studied, revealing a critical degradability threshold above which the hMSCs spread robustly and below which they are isolated and exhibit reduced spreading. This method of generating spatial gradients in MAP hydrogels can be further used to gain new insights into cell–material interactions, which can be leveraged for tissue engineering applications. [ABSTRACT FROM AUTHOR]

Published
2020
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36. Comparison of Photo Cross Linkable Gelatin Derivatives and Initiators for Three-Dimensional Extrusion Bioprinting

Author

Tigner, Thomas J., Rajput, Satyam, Gaharwar, Akhilesh K., and Alge, Daniel L.

Abstract

The objective of this study was to evaluate the utility of gelatin–norbornene (GelNB), which is cross-linkable via thiol–ene click chemistry, and the photoinitiator lithium phenyl-2,4,6 trimethylbenzoylphosphinate (LAP) for 3D bioprinting. These materials were compared to two widely used materials, gelatin-methacryloyl (GelMA) and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (I2959). Characterization of photocuring kinetics revealed that LAP markedly improved the kinetics compared to I2959, which improved stability and print fidelity. Additionally, GelNB exhibited improved photocuring kinetics, improved stability, and decreased filament spreading compared to GelMA. However, inks containing GelMA yielded at lower stress, were more easily extruded, and produced smoother filaments. NIH 3T3 fibroblasts exhibited high viability in printed constructs, regardless of the gelatin derivative or photoinitiator used. Overall, these results support the selection of LAP over I2959 and suggest that GelNB could be a useful alternative to GelMA, although further work is needed to optimize GelNB extrusion.

Published
2020
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