Photosensitive and Biomimetic Core–Shell Nanofibrous Scaffolds as Wound Dressing

Tissue engineered skin grafts that mimic the native extracellular matrix of skin has gained huge popularity among clinicians since they increase the survival rate of the patients. Phototherapy shows promising results with respect to acute and chronic pain relief, treatment of inflammatory conditions and promotion of wound healing. Here, we encapsulated a photosensitive polymer poly (3‐hexylthiophene) (P3HT) and epidermal growth factor in the core–shell‐structured Gelatin/poly(L‐lactic acid)‐co‐poly‐(ε‐caprolactone) nanofibers [Gel/PLLCL/P3GF(cs)] by coaxial spinning and studied the potential application of the Gel/PLLCL/P3GF(cs) nanofibrous scaffold as a novel skin graft. The proliferation of fibroblasts was significantly improved on Gel/PLLCL/P3GF(cs) under light stimulation compared to fibroblasts on the same scaffold under dark condition. Studies on the in vitro wound healing ability of Gel/PLLCL/P3GF(cs) showed complete closure of wound after 9 days under “light stimulation” too. Furthermore, the potential of adipose‐derived stem cells (ASCs) to differentiate to epidermal cells on Gel/PLLCL/P3GF(cs) was evaluated. The differentiated ASCs with keratinocytes morphology were only found on the light stimulated Gel/PLLCL/P3GF(cs). Our results suggest that the photosensitive core–shell Gel/PLLCL/P3GF(cs) nanofibers could be a novel substrate to aid in the reestablishment of skin architecture.     

Synthesis, characterization, electro chemistry, catalytic and biological activities of ruthenium(III) complexes with bidentate N, O/S donor ligands

New hexa-coordinated ruthenium(III) complexes of the type [RuX(2)(EPh(3))(2)(L)] (E=P or As; X=Cl or Br; L=monobasic bidentate Schiff base derived from the condensation of benzhydrazide with furfuraldehyde, 2-acetylfuran and 2-acetylthiophene) have been synthesized from the equimolar amounts of [RuX(3)(EPh(3))(3)] or [RuBr(3)(PPh(3))(2)(MeOH)] and Schiff bases in benzene. The new complexes have been characterized by analytical, spectral (IR, electronic and EPR), magnetic moment, and cyclic voltammetry. An octahedral structure has been tentatively proposed. All the complexes have exhibited catalytic activity for the oxidation of benzyl alcohol, cyclohexanol and cinnamylalcohol in the presence of N-methylmorpholine-N-oxide as co-oxidant. All the new complexes were found to be active against the bacteria such as E. coli, Pseudomonas, Salmonella typhi and Staphylococcus aureus. The activity was compared with standard Streptomycin.     

Fabrication and characterization of polyurethane patch loaded with palmarosa and cobalt nitrate for cardiac tissue engineering

Cardiac patches are attractive option in overcoming the morbidities associated with cardiac disorders. Nanofibrous scaffolds were fabricated using polyurethane (PU) added with palmarosa (PR) and cobalt nitrate (CoNO₃) using an electrospinning technique. Several characterizations were employed namely field emission scanning electron microscopy, wettability measurement, attenuated total reflectance infrared spectroscopy, thermal analysis, surface roughness measurements, and tensile testing. Further, biological response of the electrospun nanofibers were tested through coagulation study and MTS assay. As-spun composite mats showed smaller fibers than pure PU as depicted in morphology analysis. The interaction of PU with PR and CoNO₃ was confirmed in infrared spectrum and thermal analysis. The incorporation of the PR decreased the wettability and while CoNO₃ addition resulted in the hydrophilic nature as depicted in the contact angle measurements. Mechanical properties testing showed that elongation at break for the pristine PU was increased with the addition of PR and CoNO_3. The surface measurements depicted that the incorporation of PR resulted in the improvement of the surface roughness while the addition of CoNO₃ reduced the surface roughness of the pristine PU. The electrospun nanocomposites showed delayed blood clotting time compared to the pristine PU as shown in coagulation study. Both composites supported the better proliferation of fibroblast cells than pure PU. Therefore, novel composites with smaller fiber diameter, hydrophilicity, better mechanical properties, improved blood compatibility parameters, and good cell viability rates would be a promising candidate for cardiac tissue engineering.     

Chemically prepared oxides on Si(001): an XPS study

Thin oxide layers prepared on Si(001) by various chemical treatments have been investigated using X-ray photoelectron spectroscopy. The oxides are prepared by treatment with HCl, H₂SO₄ and HNO₃. The O 1s spectra consists of two peaks at 532.6 eV (low binding energy component, LBC) and 533.6 eV (high binding energy component, HBC) in all the cases. The LBC is assigned to a monatomic bridging oxygen, Si---O---Si and HBC to a monatomic non-bridging oxygen, Si---O species. Conversion of Si---O to Si---O---Si takes place on annealing the sample. The concentration of Si---O species is low in the case of HCl oxide. In in situ prepared oxide, the O 1s is predominantly due to Si---O---Si.     

Damage assessment through electrical resistance measurement in graphite fiber-reinforced composites

Experimental Techniques -     

Preorganizing linear (self-complementary) quadruple hydrogen-bonding arrays using intramolecular hydrogen bonding as the sole force

[structures: see text] In this article we describe a rational approach for prefixing multiple cooperative binding sites in an ideal spatial arrangement on a structurally rigid backbone, constrained exclusively by intramolecular hydrogen bonding. The idea is exemplified by the ability of the self-assembling constructs 1a-e and 2a,b to form hydrogen-bonded dimers, whose structural preorganization has been solely effected by intramolecular hydrogen bonding. The readily accessible amidinourea backbone has been used as a common platform for the construction of a variety of such self-assembling systems. ESI mass spectrometry and single-crystal X-ray diffraction studies have been particularly effective in investigating the self-assembling propensities of these systems. Remarkably, most the H-bonded dimers reported herein undergo an unusual mode of self-assembly, using intermolecular four-membered ring hydrogen-bonded interaction, affording extended supramolecular networks.     

On extremal problems related to integral transforms of a class of analytic functions

For γ?0 and β<1 given, let Pγ(β) denote the class of all analytic functions f in the unit disk with the normalization f(0)=f^′(0)−1=0 and satisfying the condition

     

Holographically determined isopachics and isochromatics in the neighborhood of a crack in a glass composite

The isochromatic and isopachic fringes are obtained holographically in the neighborhood of a central crack in a tensile, orthotropic glass-composite plate. The general inability to separate the principal stresses or strains from such information alone under anisotropic conditions is discussed, as are the results relative to fracture-mechanics implications.     

Efficacy of Precocene I from Desmosstachya bipinnata as an Effective Bioactive Molecules against the Spodoptera litura Fab. and Its Impact on Eisenia fetida Savigny

The sustainability of agroecosystems are maintained with agro-chemicals. However, after more than 80 years of intensive use, many pests and pathogens have developed resistance to the currently used chemistries. Thus, we explored the isolation and bioactivity of a chemical compound, Precocene I, isolated from the perennial grass, Desmosstachya bipinnata (L.) Stapf. Fractions produced from chloroform extractions showed suppressive activity on larvae of Spodoptera litura (Lepidoptera: Noctuidae), the Oriental armyworm. Column chromatography analyses identified Precocene I confirmed using FTIR, HPLC and NMR techniques. The bioactivity of the plant-extracted Dp-Precocene I was compared to a commercially produced Precocene I standard. The percentage of mortality observed in insects fed on plant tissue treated with 60 ppm Db-Precocene I was 97, 87 and 81, respectively, for the second, third and fourth instar larvae. The LC₅₀ value of third instars was 23.2 ppm. The percentages of survival, pupation, fecundity and egg hatch were altered at sub-lethal concentrations of Db-Precocene I (2, 4, 6 and 8 ppm, sprays on castor leaves). The observed effects were negatively correlated with concentration, with a decrease in effects as concentrations increased. Distinct changes in feeding activity and damage to gut tissues were observed upon histological examination of S. litura larvae after the ingestion of Db-Precocene I treatments. Comparative analyses of mortality on a non-target organism, the earthworm, Eisenia fetida, at equal concentrations of Precocene I and two chemical pesticides (cypermethrin and monocrotophos) produced mortality only with the chemical pesticide treatments. These results of Db-Precocene I as a highly active bioactive compound support further research to develop production from the grass D. bipinnata as an affordable resource for Precocene-I-based insecticides.