Role of GO and Photoinitiator Concentration on Curing Behavior of PEG-Based Polymer for DLP 3D Printing.

Photocuring kinetics in photopolymerization-based three-dimensional (3D) printing processes have gained significant attention because they determine the final dimension accuracy of the printed structures. In this study, the curing kinetics of liquid-light-curable resins, including water-dispersed graphene oxide (GO) and ultraviolet (UV)-cured acrylic resins, were investigated during digital light processing (DLP) 3D printing. Various stable composites of water-dispersed GO and UV-cured acrylic resin were prepared to fabricate 3D structures for cure-depth measurements. Several factors, including the UV-exposure conditions, photoinitiator concentration, and composition of the photopolymer resin, were found to significantly affect the cure-depth characteristics of the printed structures. The photocuring depth of the polymeric resin system was investigated as a function of the photoinitiator concentration. In addition, the study showed that the introduction of GO played a significant role in controlling the performance of the highly cross-linked network and the thickness of the cured layer. The curing characteristics of functional photocurable polymer-based DLP 3D printing contribute to process development and improvement of the quality of printed microstructures for industrial applications.

Vitrification of porcine cumulus-oocyte complexes at the germinal vesicle stage does not trigger apoptosis in oocytes and early embryos, but activates anti-apoptotic Bcl-XL gene expression beyond the 4-cell stage.

The aim of the present study was to clarify whether or not our vitrification procedure at the germinal vesicle (GV)-stage triggers the apoptotic cascade in oocytes and subsequent embryos. Immature porcine cumulus-oocyte complexes were either vitrified and warmed (vitrified group) or subjected to cryoprotectant agents (CPA group) or cultured without any treatment (control). Oocytes of all treatment groups were subjected to in vitro maturation (IVM), fertilization, and embryo culture. Apoptosis was assayed in live oocytes at the end of IVM culture and in cleavage-stage embryos after in vitro fertilization (IVF). We detected similar frequencies of DNA fragmentation, levels of caspase activity, phosphatidylserine externalization, and mRNA levels for pro-apoptotic Bax and CASP3 genes in oocytes at the end of IVM and in early embryos among all groups. However, in the vitrified group, the anti-apoptotic Bcl-XL gene was upregulated in 4-8 cell embryos, which caused an 8-fold significant increase in the Bcl-XL/Bax mRNA ratio compared with the control and CPA groups (P < 0.05). In conclusion, vitrification of porcine oocytes at the GV stage by our method did not trigger the apoptotic cascade in oocytes and subsequent embryos but triggered the upregulation of the anti-apoptotic Bcl-XL gene in embryos.

Maturation ability after transfer of freeze-dried germinal vesicles from porcine oocytes.

The purpose of this study was to examine whether freeze-dried germinal vesicles (GV) can be matured in vitro after being injected into enucleated fresh oocytes in pigs as an alternative method for conservation of genetic resources. Although no reduction of the size of GV (p = .094), resveratrol treatment significantly enhanced the survival rates following GV transfer (GVT) (p < .001). Supplementation with 100 or 200 mmol/L trehalose in freeze-drying medium significantly increased the proportions of GVs with intact nuclear membrane and DNA integrity compared with the control group. Following transfer of freeze-dried GVs into enucleated fresh oocytes, the proportion of reconstructed oocytes reached the metaphase-II stage (2.4% ± 1.4%) was significantly lower (p < .05) than that of the in vitro matured control group (83.2% ± 2.5%), it was comparable with the GVT control group (7.4% ± 2.7%). The rates of freeze-dried GVs with intact nuclear membrane and DNA stored at -20°C for 5 days were significantly higher (p < .05) than those at 4°C and room temperature. The rates of intact nuclear membrane and DNA in the freeze-dried GV stored for 15 or 30 days at -20, 4°C and RT were not significantly different. In conclusion, matured oocytes were produced derived from freeze-dried GVs.