3D Porous Polymer Scaffold-Conjugated KGF-Mimetic Peptide Promotes Functional Skin Regeneration in Chronic Diabetic Wounds.

The re-epithelialization process gets severely dysregulated in chronic nonhealing diabetic foot ulcers/wounds. Keratinocyte growth factor (KGF or FGF-7) is the major modulator of the re-epithelialization process, which regulates the physiological phenotypes of cutaneous keratinocytes. The existing therapeutic strategies of growth factor administration have several limitations. To overcome these, we have designed a KGF-mimetic peptide (KGFp, 13mer) based on the receptor interaction sites in murine KGF. KGFp enhanced migration and transdifferentiation of mouse bone marrow-derived MSCs toward keratinocyte-like cells (KLCs). A significant increase in the expression of skin-specific markers Bnc1 (28.5-fold), Ck5 (14.6-fold), Ck14 (26.1-fold), Ck10 (187.7-fold), and epithelial markers EpCam (23.3-fold) and Cdh1 (64.2-fold) was associated with the activation of ERK1/2 and STAT3 molecular signaling in the KLCs. Further, to enhance the stability of KGFp in the wound microenvironment, it was conjugated to biocompatible 3D porous polymer scaffolds without compromising its active binding sites followed by chemical characterization using Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, dynamic mechanical analysis, and thermogravimetry. In vitro evaluation of the KGFp-conjugated 3D polymer scaffolds revealed its potential for transdifferentiation of MSCs into KLCs. Transplantation of allogeneic MSCGFP using KGFp-conjugated 3D polymer scaffolds in chronic nonhealing type 2 diabetic wounds (db/db transgenic, 50-52 weeks old male mice) significantly enhanced re-epithelialization-mediated wound closure rate (79.3%) as compared to the control groups (Untransplanted -22.4%, MSCGFP-3D polymer scaffold -38.5%). Thus, KGFp-conjugated 3D porous polymer scaffolds drive the fate of the MSCs toward keratinocytes that may serve as potential stem cell delivery platform technology for tissue engineering and transplantation.

The fabrication of bifunctional supramolecular glycolipid-based nanocomposite gel: insights into electrocatalytic performance with effective selectivity towards gold.

Recovery, recycling, and reuse of metal waste have been re-intensified in the current era to build a sustainable future. In this context, gel nanocomposites were formulated by in situ reduction of gold within the low molecular weight gel matrix of synthetic glycolipid amphiphiles without using any external reducing/stabilizing agents. This strategy aroused the interest in formulating gel nanocomposites with preferential uptake of gold. The exclusive advantages owned by gold nanoparticle (GNP) embedded hydrogel offer an alternative to decorate the electrode surface without physical deposition/plating of the catalyst. Formation of GNP within the gel matrix was confirmed by the SPR peak in the UV-Visible spectrum. The particle size of 5-7 nm with zeta potential value in the range of -30.5 to -41.4 mV displayed good stability of nanoparticles in the gel matrix. Due to the encapsulation of nanoparticles within supramolecular assemblies of gel, a noteworthy increase in viscoelastic strength was observed, whereas the gelation behavior, melting temperature, and original fibrillar morphology of hydrogel remained intact. This hybrid gel exhibited good ionic conductivity (2.36 × 10-5 S cm-1) with appreciable ionic transport, remarkable oxygen reduction reaction (ORR) augmentation in reduction potential from 0 V to -0.12 V vs. Ag/AgCl as reference electrode, and excellent thermal stability in a wide temperature range. This green and efficient approach can pave the way for creating GNP-embedded hierarchical architecture that can act as bifunctional electrolyte/electrocatalyst material.

Sustainable and cost-effective ternary electrolyte Et3NHCl-AlCl3-Mg(DEP)2 for high-performance rechargeable magnesium batteries.

Cost-effective and sustainable battery materials for large-scale batteries are the need of the hour to garner renewable energy with high-performance metal battery technologies. Here, we report the high-performance and long cycle life electrolyte prepared from low-cost triethylamine hydrochloride (Et3NHCl) and aluminum chloride (AlCl3) termed as (TA) with different concentrations of magnesium diethylphosphate (Mg(DEP)2) salt. The optimized ratio of the 0.1 M Mg(DEP)2 electrolyte has shown a high ionic conductivity of 4.5 × 10-3 S cm-1 at ambient temperature and good anodic stability of 2.41 V vs. Mg/Mg2+. The dissolution/deposition of magnesium (Mg) on a Pt working electrode was systematically analyzed in this electrolyte. Cyclic voltammetry (CV) of the Mg-graphite battery was used to probe the intercalation/de-intercalation of Mg-AlCl4- ions into/from the graphite layer structure. This was confirmed by various analytical techniques, such as energy dispersive X-ray spectroscopy, X-ray diffraction technique and X-ray photoemission spectroscopy. Notably, during the galvanostatic study analysis, the assembled Mg cell delivered a high discharge capacity of 115 mA h g-1 at a high C/10 rate, with more than 180 cycles at >80% coulombic efficiency. This electrolyte will be helpful in grid-scale power storage systems in future generations.

1D alignment of Co(II) metalated porphyrin-napthalimide based self-assembled nanowires for photocatalytic hydrogen evolution.

The splitting of water into hydrogen and oxygen under visible light is an emerging phenomenon in green energy technology. Nevertheless, selecting an appropriate photocatalyst is rather significant to enhance hydrogen production on a large scale. In this context, organic photocatalysts have received considerable attention owing to their larger surface area, control in diffusion adsorption, nanostructures and electronic properties. Herein, we have developed five either free base or transition metalated porphyrin-napthalimide based donor-acceptor systems (PN1-PN5) and studied their morphology, electronic properties and catalytic behaviour. Detailed studies suggest that the Co(II) substituent D-A system (PN2) displayed a well-aligned one-dimensional (1D) nanowire with high electrical conductivity promoting remarkable photocatalytic hydrogen production rate (18 mM g-1 h-1) when compared to that of porphyrin-based derivatives reported until now. Thus, these results propose to investigate diverse metalated π-conjugated materials as photocatalysts for hydrogen production.

1,4-Dihydropyrrolo[3,2-b]pyrroles as a Single Component Photoactive Layer: A New Paradigm for Broadband Detection.

Single component organic photodetectors capable of broadband light sensing represent a paradigm shift for designing flexible and inexpensive optoelectronic devices. The present study demonstrates the application of a new quadrupolar 1,4-dihydropyrrolo[3,2-b]pyrrole derivative with spectral sensitivity across 350-830 nm as a potential broadband organic photodetector (OPD) material. The amphoteric redox characteristics evinced from the electrochemical studies are exploited to conceptualize a single component OPD with ITO and Al as active electrodes. The photodiode showed impressive broadband photoresponse to monochromatic light sources of 365, 470, 525, 589, 623, and 830 nm. Current density-voltage (J-V) and transient photoresponse studies showed stable and reproducible performance under continuous on/off modulations. The devices operating in reverse bias at 6 V displayed broad spectral responsivity (R) and very good detectivity (D*) peaking a maximum 0.9 mA W-1 and 1.9 × 1010 Jones (at 623 nm and 500 µW cm-2) with a fast rise and decay times of 75 and 140 ms, respectively. Low dark current densities ranging from 1.8 × 10-10 Acm-2 at 1 V to 7.2 × 10-9 A cm-2 at 6 V renders an operating range to amplify the photocurrent signal, spectral responsivity, and detectivity. Interestingly, the fabricated OPDs display a self-operational mode which is rarely reported for single component organic systems.

Self-assembly of t-butyloxycarbonyl protected dipeptide methyl esters composed of leucine, isoleucine, and valine into highly organized structures from alcohol and aqueous alcohol mixtures.

Short peptides composed of phenylalanine and sequences derived from amyloidogenic peptides have the ability to self-assemble to form nanostructures including hydrogels. The self-assembly of peptides composed of only hydrophobic amino acids and aliphatic protecting groups have not been investigated in detail. We have examined various aspects of nanostructures formed by N-terminal t-butyloxycarbonyl-protected aliphatic dipeptide methyl esters dissolved in various solvents. Scanning electron microscopic images indicate that depending on the sequence, position of the amino acid and solvent of dissolution, the peptides self-assemble into superstructures such as nanotubes and needles particularly from aqueous mixtures of organic solvents. Crystallization was not required for self-assembly into nanostructures. Circular dichroism and attenuated total internal reflection fourier transform infrared spectroscopy studies indicate that the peptides adopt ß-conformation in the superstructures both in solution and solid state. The nanostructures composed of entirely aliphatic moieties have the ability to bind to aromatic dyes such as Rhodamine 6G, Nile red and Congo red. They also bind to Thioflavin T although the structures do not resemble amyloid fibrils. The powder X-ray diffraction patterns suggest distinctive packing of the monomers. These structures are stabilized by intermolecular hydrogen bonds and hydrophobic interactions resulting in superstructures containing long distance order and were devoid of hemolytic activity.

Vibrational and impedance spectroscopic analyses of semi-interpenetrating polymer networks as solid polymer electrolytes.

Semi-interpenetrating polymer networks (semi-IPNs) with significant ionic conductivity (10-4 S cm-1 at ambient temperature) were studied by vibrational and impedance spectroscopies coupled with advanced analysis procedures. Vibrational spectroscopy recognized the numbers of free ions, ion pairs, ion-polymers and hydrogen bonds within the solid polymer electrolyte matrices (SPE). Electrochemical impedance spectroscopy (EIS) was used to quantify the bulk resistance and bulk relaxation time. The analyses used discrepancy-complexity plots to assess the number of free parameters properly, and EIS was further analyzed using impedance spectroscopy genetic programming (ISGP). Four compositions of PEO-polyurethane/poly(ethylene glycol) dimethyl ether (PEO-PU/PEGDME) were examined with LiClO4 salt. The polymer electrolyte composition of 30/70 PEO-PU/PEGDME resulted in the lowest relaxation times and the highest ionic conductivity. The best salt concentration was observed at an EO/Li ratio of 30 for the PEO-PU/PEGDME : LiClO4 (30/70) semi-IPN matrix. Several lithium salts of different anions were examined at an EO/Li ratio of 10, and the ionic conductivity achieved varied in the order -N(CF3SO2)2- > -ClO4- > -(CF3SO3)- > -I-/I3-.

Data on bone marrow stem cells delivery using porous polymer scaffold.

Low bioavailability and/or survival at the injury site of transplanted stem cells necessitate its delivery using a biocompatible, biodegradable cell delivery vehicle. In this dataset, we report the application of a porous biocompatible, biodegradable polymer network that successfully delivers bone marrow stem cells (BMSCs) at the wound site of a murine excisional splint wound model. In this data article, we are providing the additional data of the reference article "Porous polymer scaffold for on-site delivery of stem cells - protects from oxidative stress and potentiates wound tissue repair" (Ramasatyaveni et al., 2016) [1]. This data consists of the characterization of bone marrow stem cells (BMSCs) showing the pluripotency and stem cell-specific surface markers. Image analysis of the cellular penetration into PEG-PU polymer network and the mechanism via enzymatic activation of MMP-2 and MMP-13 are reported. In addition, we provide a comparison of various routes of transplantation-mediated BMSCs engraftment in the murine model using bone marrow transplantation chimeras. Furthermore, we included in this dataset the engraftment of BMSCs expressing Sca-1(+)Lin(-)CD133(+)CD90.2(+) in post-surgery day 10.

Porous polymer scaffold for on-site delivery of stem cells--Protects from oxidative stress and potentiates wound tissue repair.

Wound healing by cell transplantation techniques often suffer setbacks due to oxidative stress encountered at injury sites. A porous polyethyleneglycol-polyurethane (PEG-PU) scaffold that facilitates cell delivery and boosts tissue repair was developed through semi-interpenetrating polymer network approach. The key physico-chemical properties assessed confirms these polymeric matrices are highly thermostable, barostable, degrade at an acidic pH (5.8), biodegradable, cytocompatible and possess excellent porosity. Mechanism of cellular penetration into porous polymer networks was evident by a ≥6 - fold increase in gene expression of MMP-13 and MMP-2 via activation of Akt and Erk. H2O2-induced apoptosis of mouse bone marrow stem cells (BMSCs) was abrogated in presence of polymer networks indicating a protective effect from oxidative stress. Transplantation of BMSC + PEG-PU at murine excisional splint wound site depicted significant increase in fibroblast proliferation, collagen deposition, anti-oxidant enzyme activities of catalase, SOD and GPx. Furthermore it significantly decreased expression of pro-inflammatory cytokines (IL-1ß, TNF-α, IL-8, etc) with a concomitant increase in anti-inflammatory cytokines (IL-10, IL-13) at an early healing period of day 7. Finally, immunostaining revealed an enhanced engraftment and vascularity indicating an accelerated wound tissue closure. This pre-clinical study demonstrates the proof-of-concept and further necessitates their clinical evaluation as potential cell delivery vehicle scaffolds.

Hierarchical mesoporous In2O3 with enhanced CO sensing and photocatalytic performance: distinct morphologies of In(OH)3 via self assembly coupled in situ solid-solid transformation.

The present investigation details our interesting findings and insights into the evolution of exotic hierarchical superstructures of In(OH)3 under solvothermal conditions. Controlled variation of reaction parameters such as, reactant concentration, solvent system, crystal structure modifiers, water content along with temperature and time, yielded remarkable architectures. Diverse morphologies achieved for the first time includes (i) raspberry-like hollow spheres, (ii) nanosheet-assembled spheres, (iii) nanoparticle-assembled spheres, (iv) nanocube-assembled hollow spheres, (v) yolk-like spheres, (vi) solid spheres, (vii) nanosheets/flakes, and (viii) ultrafine nanosheets. A plausible mechanism is proposed based on the evidence gathered from a comprehensive analysis aided by electron microscopy and X-ray diffraction studies. Key stages of morphological evolution could be discerned and rationally correlated with nucleation, growth, oriented attachment, and Ostwald ripening mediated by dissolution-redeposition mechanism coupled with solid evacuation. Remarkably phase-pure bcc-In2O3 with retention of precursor morphology could be realized postcalcination at 400 °C, which underlines the advantage of this strategy. Two typical hierarchical structures (raspberry-like hollow spheres and nanoparticles assembled spheres) were investigated for their gas sensing and photocatalytic performances to highlight the advantages offered by nanostructuring. An impressive sensor response, Smax ≈ 7340 and 4055, respectively for the two structures along with appreciably fast response/recovery times over a wide concentration range and as low as 1 ppm exhibits the superior sensitivity toward carbon monoxide (CO). When compared to commercial In2O3, estimated rate constant indicates ∼3-4 times enhancement in photocatalytic activity of the substrates toward Rhodamine-B.

Polymer-nanocomposite brush-like architectures as an all-solid electrolyte matrix.

Herein, we report on polymer-nanocomposites with brush-like architectures and evaluate their feasibility as an all-solid electrolyte matrix supporting Li(+)-ion conduction. Showcased as a first example in the domain of electrolyte research, the study probes several key factors, such as (i) core morphology, (ii) surface modifiers/functionality, (iii) grafting length, and (iv) density of the brushes, and determines their role on the overall electrochemical properties of these nanostructured organic-inorganic hybrids. Nanostructured titania was synthesized via wet-chemical approaches using either controlled hydrolysis or hydrothermal methods. Exercising suitable control on reaction parameters led to well-defined morphologies/phases, such as nanoparticles, nanospindles, nanourchins, nanorods or nanotubes, in either anatase, rutile or mixed forms. Covalent anchoring on titania nanostructures was achieved using dopamine, gallic acid and glycerol as small organic moieties. A one-pot process of priming the available surface functional groups postmodification with isocyanate chemistry was followed by grafting polyethylene glycol monomethyl ethers of desired chain lengths. Finally, complexation with lithium salt yielded electrolyte compositions where the ethylene oxide (EO) fractions aid in ion-solvation with ease. The synthesized materials were characterized in detail employing XRD, TEM, DRS-UV, FTIR, micro-Raman, TG-DTA and DSC at each stage to confirm the products and ascertain the physicochemical properties. Comprehensive evaluation using temperature-step electrochemical impedance spectroscopy (EIS) of these brush-like nanocomposites provided crucial leads toward establishing a plausible physical model for the system and understanding the mechanism of ion transport in these all-solid matrices. The preliminary results on ionic conductivity (σ) obtained for some of the compositions are estimated to be within the range of ∼10(-4) to 10(-5) S cm(-1) in the temperature window of the study that holds excellent promise for further improvement.

Viable method for the synthesis of biphasic TiO2 nanocrystals with tunable phase composition and enabled visible-light photocatalytic performance.

Here we demonstrate a facile method to synthesize high-surface-area TiO(2) nanoparticles in aqueous-ethanol system with tunable brookite/rutile and brookite/anatase ratio possessing high surface area that exhibits enhanced photoactivity. Titanium tetrachloride (TiCl(4)) is used as the metal precursor of choice and the tuning of phase compositions are achieved by varying the water:ethanol ratio, used as mixed solvent system. The synthesized samples were characterized in detail using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), BET nitrogen sorption measurements, and UV-vis diffuse reflectance spectroscopy (UV-DRS). The photocatalytic activity of biphasic TiO(2) nanocrystals was evaluated by following the degradation kinetics of rhodamine-B dye in aqueous solution and under visible light. Mixed-phase TiO(2) nanostructures composing 83% brookite and 17% of rutile exhibited superior photoactivity when compared to Degussa P25 and phase-pure anatase nanocrystals. The exceptional photocatalytic activity of the synthesized nanostructures can be elucidated on the account of their large surface area and biphasic composition. On the basis of the detailed investigation reported herein, we conclude that tuning the ethanol volume in the mixed-solvent reaction system holds the key to tailor and control the final TiO(2) phase obtained.

Investigations on the mechanisms of ionic conductivity in PEO-PU/PAN semi-interpenetrating polymer network-salt complex polymer electrolytes: an impedance spectroscopy study.

This paper is a first comprehensive study on the correlated ion transport mechanisms contributing to the overall conductivity behavior in a new class of poly(ethylene oxide)-polyurethane/polyacrylonitrile (PEO-PU/PAN) semi-interpenetrating polymer networks (semi-IPNs)-salt complex polymer electrolytes. A simultaneous investigation of the electrical response on PEO-PU/PAN/LiClO(4) and PEO-PU/PAN/LiCF(3)SO(3) semi-IPNs with varying EO/Li mole ratios (100, 60, 30, 20, 15, 10) has been carried out by impedance spectroscopy. Analysis of the complex plane and spectroscopic plots indicated the presence of two microscopic phases corresponding to the PEO-PU and PAN domains, which leads to space charge polarization in these systems. A suitably modified approach based on the universal power law (UPL) considering the independent contribution from the individual microphases of semi-IPNs facilitates a complete interpretation of the spectroscopic profiles for the real component of conductivity (sigma'(omega)). The sigma'(omega) spectroscopic profiles were fitted with two power law equations, where the frequency region up to approximately 300 kHz is the conductivity profile associated with the PAN phase and beyond this is the superimposed contribution of the PEO-PU phase. Simulated fits using the UPL equation revealed two relaxation times (tau(PEO)(-)(PU), tau(PAN)) related to ionic hopping in the PEO-PU and PAN phases in addition to the conductivity relaxation time (tau(peak)) determined from the Debye peaks. The respective power law exponents (n(PEO)(-)(PU) approximately 0.5-0.8, n(PAN) approximately 1.0-1.6) indicate that though cationic hopping in the softer PEO-PU phase is favored, anionic hopping in the PAN phase contributes significantly to the charge transport processes in these semi-IPNs. Correlation of the experimental results with the simulated fits enable us to distinguish the effects of semi-IPN composition, temperature, morphology, ion-ion, and ion-polymer interactions, which influence the microscopic molecular events, involved in the charge transport in these complex semi-IPN polymer electrolytes.