Browsing by Author "Guo, Jason L."
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Item Evaluating the physicochemical effects of conjugating peptides into thermogelling hydrogels for regenerative biomaterials applications(Oxford University Press, 2021) Pearce, Hannah A.; Jiang, Emily Y.; Swain, Joseph W.R.; Navara, Adam M.; Guo, Jason L.; Kim, Yu Seon; Woehr, Andrew; Hartgerink, Jeffrey D.; Mikos, Antonios G.Thermogelling hydrogels, such as poly(N-isopropylacrylamide) [P(NiPAAm)], provide tunable constructs leveraged in many regenerative biomaterial applications. Recently, our lab developed the crosslinker poly(glycolic acid)-poly(ethylene glycol)-poly(glycolic acid)-di(but-2-yne-1,4-dithiol), which crosslinks P(NiPAAm-co-glycidyl methacrylate) via thiol-epoxy reaction and can be functionalized with azide-terminated peptides via alkyne-azide click chemistry. This study’s aim was to evaluate the impact of peptides on the physicochemical properties of the hydrogels. The physicochemical properties of the hydrogels including the lower critical solution temperature, crosslinking times, swelling, degradation, peptide release and cytocompatibility were evaluated. The gels bearing peptides increased equilibrium swelling indicating hydrophilicity of the hydrogel components. Comparable sol fractions were found for all groups, indicating that inclusion of peptides does not impact crosslinking. Moreover, the inclusion of a matrix metalloproteinase-sensitive peptide allowed elucidation of whether release of peptides from the network was driven by hydrolysis or enzymatic cleavage. The hydrophilicity of the network determined by the swelling behavior was demonstrated to be the most important factor in dictating hydrogel behavior over time. This study demonstrates the importance of characterizing the impact of additives on the physicochemical properties of hydrogels. These characteristics are key in determining design considerations for future in vitro and in vivo studies for tissue regeneration.Item Three-dimensional printing of multilayered tissue engineering scaffolds(Elsevier, 2018) Bittner, Sean M.; Guo, Jason L.; Melchiorri, Anthony; Mikos, Antonios G.The field of tissue engineering has produced new therapies for the repair of damaged tissues and organs, utilizing biomimetic scaffolds that mirror the mechanical and biological properties of host tissue. The emergence of three-dimensional printing (3DP) technologies has enabled the fabrication of highly complex scaffolds that offer a more accurate replication of native tissue properties and architecture than previously possible. Of strong interest to tissue engineers is the construction of multilayered scaffolds that target distinct regions of complex tissues. Musculoskeletal and dental tissues in particular, such as the osteochondral unit and periodontal complex, are composed of multiple interfacing tissue types, and thus benefit from the usage of multilayered scaffold fabrication. Traditional 3DP technologies such as extrusion printing and selective laser sintering have been used for the construction of scaffolds with gradient architectures and mixed material compositions. Additionally, emerging bioprinting strategies have been used for the direct printing and spatial patterning of cells and chemical factors, capturing the complex organization found in the body. To better replicate the varied and gradated properties of larger tissues, researchers have created scaffolds composed of multiple materials spanning natural polymers, synthetic polymers, and ceramics. By utilizing high-precision 3DP techniques and judicious material selection, scaffolds can thus be designed to address the regeneration of previously challenging musculoskeletal, dental, and other heterogeneous target tissues. These multilayered 3DP strategies show great promise in the future of tissue engineering.