Diabetes mellitus (DM) is a chronic metabolic disease. Current therapies, including islet transplantation suffer instant blood mediated inflammatory reaction, nutrition and oxygen supply deficiency. Graphene oxide (GO) has shown to promote proliferation of different cells and alginate-based scaffolds are alternatives for beta-pancreatic cell functional improvement. We developed an alginate-GO based hydrogel that allows encapsulation and supporting beta-pancreatic cell survival. Physicochemical analysis revealed that a high GO concentration contributed to the morphological and chemical modification of the polymer matrix. Further analysis showed that alginate-GO hydrogel presented a more compact structure, less swelling, and lower degradation rate at high GO concentrations. Mechanical analysis revealed similar behaviour to that of the pancreas. Biocompatibility analysis demonstrated a relative increase in viability, proliferation, and cellular respiration due to GO content. 25 µg/mL alginate-GO hydrogel is a potential candidate for cell encapsulation and in vitro studies suggest a low cytotoxic effect in pancreatic cells, and enhanced functional behaviour, which may be favourable for diabetes treatment. Graphical Abstract

Supercapacitors are common devices in electrical circuits that produce electrical pulses at high power levels in short periods of time. Electrodes for supercapacitors were prepared with activated carbon. Activated carbon was obtained from cassava peels treated by chemical activation with potassium hydroxide (KOH) and phosphoric acid (H3PO4), each at two different concentrations and at one carbonization temperature. Electrochemical performance of the prepared electrodes was obtained by means of cyclic voltammetry and galvanostatic charge-discharge in a 3-electrode system with an electrolytic solution of sulfuric acid (H2SO4) 1 M. Cyclic voltammetry allowed to indentify a behavior of supercapacitors in a potential window of -0.4V to 0.6V. Activated carbon derived from cassava peel with the highest specific surface area (398.46 m2/g) has exhibited the maximum specific capacitance of 64.18 F/g.

Human mesenchymal stem cells (hMSC) represent a unique and promising platform because of their ability to promote soft tissue regeneration, particularly their ability to differentiate into adipocytes, which are important for adipose tissue regeneration. In this context, type I collagen is the most abundant extracellular matrix component of adipose tissue and can act as a natural spheroid source to support the differentiation process of stem cells. However, spheroids based on collagen and hMSCs without pro-angiogenic factors that can induce adipogenesis have not yet been investigated. In this study, we focused on developing collagen-hMSC spheroids capable of differentiating into adipocyte-like cells in a short time (eight culture days) without adipogenic factors, with potential applications in adipose tissue repair. The physical and chemical properties of the spheroids indicated successful cross-linking of collagen. Upon spheroid development, stability, cell viability, and metabolic activity of the constructs were maintained. During adipogenesis, cell morphology shows significant changes, in which cells change from a fibroblast-like shape to an adipocyte-like shape, and adipogenic gene expression after eight days of cell culture. These results support the utility of collagen-hMSC 3 mg mL-1 collagen concentration spheroids to differentiate into adipocyte-like cells in a short time without adverse effects on biocompatibility, metabolic activity, or cell morphology, suggesting that this construct may be used in soft tissue engineering.

The present study was developed to reinforce a thermoplastic matrix with carbonaceous material to improve its thermal and mechanical properties. Composite materials formed from the homogenization of polylactic acid (PLA) and reduced graphitic oxide (RGO) were synthesized and characterized, reinforcement of the polymer’s thermomechanical properties and the adequate homogeneity ratio in the dispersion of the composite material were studied. Graphitic oxide (GO) was synthesized by the modified Hummers method, followed by thermal exfoliation. The chemical composition and the structure of RGO were studied by infrared (FT-IR) and Raman spectroscopies, respectively. PLA composites with different RGO contents (2 and 3% by weight) were prepared and compared in terms of distribution of RGO in the matrix and morphology, using scanning electron microscopy. The thermal stability of the composites was determined through thermogravimetric analysis. Torque of the different composites was measured, which increased at 21%; the tensile test showed an improvement in the mechanical parameters of the composites because the RGO favors the rigidity of the composite. In addition, the oxygenated functional groups present in the RGO allowed a more significant interaction with the PLA matrix, which results in an effective reinforcement of the mechanical properties of the composite material.

Three-dimensional matrices are a new strategy used to tackle type I diabetes; a chronic metabolic disease characterized by the destruction of beta pancreatic cells. Type I collagen is an abundant extracellular matrix (ECM), component that has been used to support cell growth. However, pure collagen possesses some difficulties including low stiffness and strength, and high susceptibility to cell-mediated contraction. Therefore, we developed a collagen hydrogel with a poly(ethylene glycol) diacrylate (PEGDA) interpenetrating network (IPN), functionalized with vascular endothelial growth factor (VEGF) to mimic the pancreatic environment for the sustenance of beta-pancreatic cells. We analyzed the physicochemical characteristic of the hydrogels and found that they were successfully synthesized. The mechanical behavior of the hydrogels improved with the addition of VEGF, and the swelling degree and the degradation were stable over time. In addition, it was found that 5 ng/mL VEGF-functionalized collagen/PEGDA IPN hydrogels sustained and enhanced viability, proliferation, respiratory capacity and functionality of beta pancreatic cells. Hence, this is a potential candidate for future preclinical evaluation, which may be favorable for diabetes treatment.