Skeletal muscle tissue engineering (SMTE) employs designed biomaterial scaffolds for promoting myogenic differentiation of myoblasts to functional myotubes. Oxidative stress plays a significant role in the biocompatibility of biomaterials as well as in the fate of myoblasts during myogenesis and is also associated with pathological conditions such as myotonic dystrophy. The inherent electrical excitability of muscle cells inspired the use of electroactive scaffolds for SMTE. Conducting polymers attracted the attention of researchers for their use in muscle tissue engineering. However, poor biocompatibility, biodegradability and development of oxidative stress associated immunogenic response limits the extensive use of synthetic conducting polymers for SMTE. In order to address the limitations of synthetic polymers, intrinsically electroactive and antioxidant silk fibroin/melanin composite films and electrospun fiber mats were fabricated and evaluated as scaffolds for promoting myogenesis in vitro. Melanin incorporation modulated the thermal stability, electrical conductivity of scaffolds, fiber alignment in electrospun mats and imparted good antioxidant properties to the scaffolds. The composite electrospun scaffolds promoted myoblast assembly and differentiation into uniformly aligned high aspect ratio myotubes. The results highlight the significance of scaffold topography along with conductivity in promoting myogenesis and the potential application of silk nanofibrous composite as electoractive platform for SMTE.
In the present work, electrospraying of an organic molecule is carried out using various solvents, obtaining fibril structures along with a range of distinct morphologies. Solvent characteristics play a major role in achieving the morphology of the organic material. A thiophene derivative (7, 9-di (thiophen-2-yl)-8H-cyclopenta[a]acenaphthylen-8-one) (DTCPA) of donor-acceptordonor (DAD) architecture is used to study this solvent effect. Seven solvents with decreasing vapour pressure are selected for experiments. Electrospraying is conducted at a solution concentration of 1.5 wt % and a constant applied voltage of 15 kV. Gradual transformation in morphology of the electrospun product from spikes-sphere to only spikes is observed. A mechanism describing this transformation is proposed based on the electron micrograph analysis and XRD analysis. These data indicate that the morphological change is due to the synergistic effect of both vapour pressure and dielectric constant of the solvents. Through a reasonable control over the crystallites size and morphology along with supporting transformation mechanism theory, this study elucidates electrospraying as a prospective method for designing the architectures in organic electronics.
In this study, the degradation process of a conventional P3HT:PC 61 BM bulk heterojunction solar cell device due to light-induced aging is evaluated. This structure is chosen so as to reduce the number of interface layers. Continuous light aging is done under AM1.5G light, and devices are analyzed in short periods. The measured electrical properties, such as current−voltage, capacitance−voltage, and capacitance−frequency characteristics, and optical and structural properties suggested the process of device degradation progression. In order to investigate the photodegradation of the device and the trap state formation, various device parameters are determined, such as the density of trap states, trap distribution width, peak trap state position, carrier concentration, and built-in potential. The dual peak nature is observed in the capacitance−voltage spectra of the light-aged device. Formation of defect peaks should be attributed to trap states as well as morphological changes: modification at the donor/acceptor and semiconductor/electrode interface. Additionally, the defect peak intensity increases as the light aging period increases. The calculated carrier concentration and density of trap states are observed to be correlated with the device performance. The detailed analysis of the device properties indicates that interface-induced changes are the initial points of device degradation. The initial point of degradation primarily affects short-circuit current and fill factor (FF). Observed changes in the current density, J SC , and FF are mainly associated with an increase in the series resistance, R s . Structural and optical properties of as-prepared and aged devices revealed that there is not much change in the absorbance and crystallinity. These results corroborate that the initial device degradation is mainly due to the electrical part (various resistance) associated with the device. Further, the doublet in the capacitance spectrum under the illuminated condition is discussed. The burn-in loss of the solar cell is connected with an increase in the density of trap states. This work provides direct evidence of the formation of defect states in the device, which is portrayed in the capacitance−voltage spectra of aged samples under the illuminated condition.
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