Experimental and theoretical analysis of organic dyes having a double D-π-A configurations for dye-sensitized solar cells.

Two spiro-like organic dyes linked at the thiophene bridge (KS-11 and KS-12) together with the original rod-shaped D-π-A configuration (C1) were designed, synthesized, and characterized based on their electronic structure, and determine the photophysical and photovoltaic properties for its application in dye-sensitized solar cells. Compared to C1, the double D-π-A spiro-like configuration, which consists of two separated light-harvesting moieties, was found to be beneficial to photocurrent generation provided that they are separated properly to prevent intramolecular exciton annihilation. This was observed when KS-11, which is linked at the ß-position of the thiophene moiety of D-π-A, was compared with KS-12, where the two D-π-A are linked with an additional thiophene using a α-ß linkage. The results show that KS-12 produced a 20% and 17% increase in photovoltaic efficiency under simulated AM 1.5G solar irradiation compared to KS-11 and C1, respectively. This increase in photovoltaic performance is credited mostly to the reduction of recombination effects and the increase in the density of states at the semiconductor surface due to high dye loading and better charge-transfer properties.

Black Phosphorus (BP) Nanodots for Potential Biomedical Applications.

Recently, the appeal of 2D black phosphorus (BP) has been rising due to its unique optical and electronic properties with a tunable band gap (≈0.3-1.5 eV). While numerous research efforts have recently been devoted to nano- and optoelectronic applications of BP, no attention has been paid to promising medical applications. In this article, the preparation of BP-nanodots of a few nm to <20 nm with an average diameter of ≈10 nm and height of ≈8.7 nm is reported by a modified ultrasonication-assisted solution method. Stable formation of nontoxic phosphates and phosphonates from BP crystals with exposure in water or air is observed. As for the BP-nanodot crystals' stability (ionization and persistence of fluorescent intensity) in aqueous solution, after 10 d, ≈80% at 1.5 mg mL(-1) are degraded (i.e., ionized) in phosphate buffered saline. They showed no or little cytotoxic cell-viability effects in vitro involving blue- and green-fluorescence cell imaging. Thus, BP-nanodots can be considered a promising agent for drug delivery or cellular tracking systems.

Low-level laser therapy promotes the osteogenic potential of adipose-derived mesenchymal stem cells seeded on an acellular dermal matrix.

This study investigates the feasibility of using an adipose-derived mesenchymal stem cell (ASC)-seeded acellular dermal matrix (ADM) along with low-level laser therapy (LLLT) to repair bone defect in athymic nude mice. Critical-sized calvarial defects were treated either with ADM, ADM/LLLT, ADM/ASCs, or ADM/ASCs/LLLT. In micro-computed tomography scans, the ADM/ASCs and the ADM/ASCs/LLLT groups showed remarkable bone formation after 14 days. Additionally, bone regeneration in the ADM/ASCs/LLLT group was obvious at 28 days, but in the ADM/ASCs group at 56 days. Bone mineral density and bone tissue volume in the ADM/ASCs/LLLT group significantly increased after 7 days, but in the ADM/ASCs group after 14 days. Histological analysis revealed that the defects were repaired in the ADM/ASCs and the ADM/ASCs/LLLT group, while the defects in the ADM and the ADM/LLLT groups exhibited few bone islands at 28 and 56 days. The successful seeding of ASCs onto ADM was confirmed, and LLLT enhanced the proliferation and the survival of ASCs at 14 days. Our results indicate that ASC-seeded grafts promote bone regeneration, and the application of LLLT on ASC-seeded ADM results in rapid bone formation. The implantation of an ASC-seeded ADM combined with LLLT may be used effectively for bone regeneration.

Enhanced wound healing effect of canine adipose-derived mesenchymal stem cells with low-level laser therapy in athymic mice.

BACKGROUND: Adipose-derived mesenchymal stem cells (ASCs) are attractive cell source for skin tissue engineering. However, one obstacle to this approach is that the transplanted ASC population can decline rapidly in the recipient tissue. OBJECTIVE: The aim of this study was to investigate the effects of low-level laser therapy (LLLT) on transplanted canine ASCs in a skin wound animal model. METHODS: LLLT, ASC transplantation (ASCs) and ASC transplantation with LLLT (ASCs+LLLT) were applied to the wound bed in athymic mice. Wound healing was assessed by gross evaluation and by hematoxylin and eosin staining. The survival, differentiation and secretion of vascular endothelial growth factor and basic fibroblast growth factor of the ASCs were evaluated by immunohistochemistry and Western blotting. RESULTS: The ASCs and ASCs+LLLT groups stimulated wound closure and histological skin regeneration. The ASCs+LLLT group enhanced the wound healing, including neovascularization and regeneration of skin appendages, compared with the ASCs group. The ASCs contributed skin regeneration via differentiation and secretion of growth factors. In the ASCs+LLLT group, the survival of ASCs was increased by the decreased apoptosis of ASCs in the wound bed. The secretion of growth factors was stimulated in the ASCs+LLLT group compared with the ASCs group. CONCLUSION: These data suggest that LLLT is an effective biostimulator of ASCs in wound healing that enhances the survival of ASCs and stimulates the secretion of growth factors in the wound bed.

Functional recovery after spinal cord injury in dogs treated with a combination of Matrigel and neural-induced adipose-derived mesenchymal Stem cells.

BACKGROUND AIMS: Previous studies have reported that scaffold or cell-based transplantation may improve functional recovery following spinal cord injury (SCI), but these results were based on neuronal regeneration and cell replacement. In this study, we investigated whether a combination of Matrigel and neural-induced mesenchymal stem cells (NMSC) improved hindlimb function in dogs with SCI, and what mechanisms were involved. METHODS: We pre-differentiated canine adipose-derived mesenchymal stem cells into NMSC. A total of 12 dogs subjected to SCI procedures were assigned to one of the following three transplantation treatment groups: phosphate-buffered saline (PBS); Matrigel; or Matrigel seeded with NMSC. Treatment occurred 1 week after SCI. Basso, Beattie and Bresnahan (B.B.B.) and Tarlov scores, histopathology, immunofluorescence staining and Western blot analysis were used to evaluate the treatment effects. RESULTS: Compared with dogs administered PBS or Matrigel alone, dogs treated with Matrigel + NMSC showed significantly better functional recovery 8 weeks after transplantation. Histology and immunochemical analysis revealed that the combination of Matrigel + NMSC reduced fibrosis from secondary injury processes and improved neuronal regeneration more than the other treatments. In addition, the combination of Matrigel + NMSC decreased the expression of inflammation and/or astrogliosis markers. Increased expressions of intracellular molecules related to neuronal extension, neuronal markers and neurotrophic factors were also found in the Matrigel + NMSC group. However, the expression of nestin as a neural stem cell marker was increased with Matrigel alone. CONCLUSIONS: The combination of Matrigel + NMSC produced beneficial effects in dogs with regard to functional recovery following SCI through enhancement of anti-inflammation, anti-astrogliosis, neuronal extension and neuronal regeneration effects.

Charge-transfer interaction in single-walled carbon nanotubes with tetrathiafulvalene and their applications.

We observed that single-walled carbon nanotube (SWNT) was aligned in the presence of TTF This alignment was induced by a specific interaction between SWNT and tetrathiafulvalene (TTF), a well-known organic donor. The interaction between the two molecules can be explained by a charge-transfer, which was confirmed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The binding energies of S (2P1/2) and S (2P3/2) were shifted from 163.0 eV and 164.1 eV to 163.9 eV and 165.1 eV, respectively. In Raman spectra of the SWNT-TTF, three peaks of SWNT in radial breathing mode were also upshifted by 4-5 cm(-1). The charge-transfer interaction also contributed in modifying the electronic structure of SWNT and furthermore enhanced the electrical conductivity of SWNT. A more conductive thin film was fabricated using the SWNT-TTF Four-probe measurement revealed that the surface resistance of the SWNT-TTF film was reduced to 4.359 omega at room temperature while that of SWNT film was 6.894 omega. These results enable carbon nanotubes to be utilized more for practically for industrial applications in fabricating peculiar nano-sized building blocks.