Bioderived dyes-mediated vat photopolymerization 3D printing of chitosan hydrogels for tissue engineering

The importance of 3D printable hydrogels is constantly increasing in the field of tissue engineering, due to their characteristic structure and similarity with the human body extracellular matrix (ECM). Herein, Quinizarin-based bioderived photoactive dyes were employed for the 3D printing of methacrylated chitosan by vat pho-topolymerization (VPP). Dyes are commonly needed in VPP to obtain good resolution avoiding the light scattering in the vat, here the bioderived molecules had further utility granting the printability with good resolution while acting both as photosensitizers and fillers/crosslinkers. Defined and detailed architectures in the range of millimetres were obtained with low printing times showing for the first time the possibility to obtain all-chitosan 3D structures with suspended features by Digital Light Processing (DLP), which is a form of vat photopolymerization; such a result is not achievable without the quinizarin-derived dyes. The same structures were achieved with an opti-mized concentration of poly(ethylene glycol) diacrylate, as a comparison, enhancing the resolution. For all the formulations, the important feature to obtain the gel printability (considering reactiveness, viscosity, shear thinning behaviour, mechanical properties and stability) were evaluated. The hydrogels mechanical character-ization and swelling properties were also tested and reported. Lastly, the possible application in tissue engi-neering was also evaluated through cell proliferation analysis over samples, including metabolic activity and DNA contempt assays. The use of such bioderived photoactive molecules that simultaneously act as photosensitizer enhancing the ink reactivity, as dye improving the definition of the final structures and as filler/crosslinker increasing the me-chanical stability, could represent a valuable route for the DLP printing of soft hydrogels

The Application of Computer, Digital, and Telecommunications Technologies to the Clinical Preparation of Teachers

Computer-mediated communication (CMC) is becoming common place in the preparation of teachers. This chapter will focus on the application of CMC and will provide insight on how technology can be used in P-12 classrooms and potentially impact student learning. The purpose of the chapter is to: (a) describe the development, implementation, outcomes, and sustainability of a pre-service teacher (PST) supervision model arranged around digital technology and telecommunications, providing supervision and support for PSTs engaged in a student teaching internship, and (b) to discuss how the technology utilized may later be utilized by participating PSTs in their future classrooms (specifically videoconferencing, instant messaging, video sharing, and the critical analysis and reflection of current practices). The authors created a virtual-geographical third space in the form of a Teaching Lab that was mediated with a multimedia platform and designed around the principle of Cultural-Historical Activity Theory (CHAT). The authors also provided opportunities for PSTs to interact within that space for reflection and the sharing of best practices.https://nsuworks.nova.edu/fse_facbooks/1001/thumbnail.jp