Synthesis of a Zirconium Complex of an N,O-type p-tert-Butylcalix[4]arene and Its Application in Some Multicomponent Reactions.

The synthesis and characterization of a new octahedral Zr(IV) complex of oxygen-depleted N,O-type calixarene ligand comprising two distal-functionalized pyrazole rings have been reported. The cone shape and structure of the prepared complex were confirmed univocally by single-crystal X-ray diffraction and NMR studies. The Zr metal lies at 2.091 Å from the plane of the calixarene ring. This complex has been utilized as an efficient catalyst for the synthesis of Biginelli adducts, bis(indolyl)methanes, and coumarins. This complex (Cl2Zr-calixarene) showed superior activity for these multicomponent reactions in comparison to the corresponding Ti(IV) and Zn(II) analogues. Ferrocene-appended bis(indolyl)methane, prepared using this catalyst, was also evaluated for its anticancer activity against the A-172 cell line.

Natural protein-based electrospun nanofibers for advanced healthcare applications: progress and challenges.

Electrospinning is an electrostatic fiber fabrication technique that operates by the application of a strong electric field on polymer solution or melts. It is used to fabricate fibers whose size lies in the range of few microns to the nanometer range. Historic development of electrospinning has evinced attention due to its outstanding attributes such as small diameter, excellent pore inter-connectivity, high porosity, and high surface-to-volume ratio. This review aims to highlight the theory behind electrospinning and the machine setup with a detailed discussion about the processing parameters. It discusses the latest innovations in natural protein-based electrospun nanofibers for health care applications. Various plant- and animal-based proteins have been discussed with detailed sample preparation and corresponding processing parameters. The usage of these electrospun nanofibers in regenerative medicine and drug delivery has also been discussed. Some technical innovations in electrospinning techniques such as emulsion electrospinning and coaxial electrospinning have been highlighted. Coaxial electrospun core-shell nanofibers have the potential to be utilized as an advanced nano-architecture for sustained release targeted delivery as well as for regenerative medicine. Healthcare applications of nanofibers formed via emulsion and coaxial electrospinning have been discussed briefly. Electrospun nanofibers have still much scope for commercialization on large scale. Some of the available wound-dressing materials have been discussed in brief.

Erratum: Majumder, S. et al. Zinc Oxide Nanoparticles Functionalized on Hydrogel Grafted Silk Fibroin Fabrics as Efficient Composite Dressing. Biomolecules 2020, 10, 710.

The authors wish to make the following correction to this paper [...].

Zinc Oxide Nanoparticles Functionalized on Hydrogel Grafted Silk Fibroin Fabrics as Efficient Composite Dressing.

Recent advances in woundcare is targeted towards developing active-dressings, where multiple components are combined to provide a suitable environment for rapid healing. The aim of the present research is to study the preparation of biomimic composite wound dressings by the grafting of hydrogel on silk fibroin fabric. The swelling ability of hydrogel grafted silk fibroin fabric was optimized by changing the initiator concentration. In order to impart antimicrobial properties, these dressing are further coated sono-chemically with zinc oxide nanoparticles. The water vapor transmission rate of the prepared samples was measured. The conformation of silk fibroin proteins after grafting with hydrogel was also confirmed using Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the zinc oxide-coated silk fibroin fabric and hydrogel-coated silk fibroin was studied using Scanning Electron Microscope (SEM). The antimicrobial activity of the zinc oxide-coated samples was studied against E coli. The cytocompatibility of the prepared dressing materials were evaluated using L929 fibroblast cells. MTT assay and phase contrast microscopic studies showed that the adherence, growth, and proliferation of the L929 fibroblast cells that were seeded on zinc oxide nanoparticles on the functionalized hydrogel-coated silk fibroin dressing was significantly higher than that of pure silk fibroin due to the highly porous, bio-mimic structure that allowed ease of passage of nutrients, growth factors, metabolites, and the exchange of gases which is beneficial for successful regeneration of damaged tissues. The expression of TNF-α and IL-2 were not significantly higher than that of control. The proposed composite dressing would be a promising material for wound dressing and regenerative medicine but in order to prove the efficacy of these materials, more in vivo experiments and clinical tests are required to be conducted in future.

A Novel Synthesis of the Graphene Oxide-Silver (GO-Ag) Nanocomposite for Unique Physiochemical Applications.

Graphene oxide-silver nanocomposite (GO-Ag) was fabricated via the sonochemical method, which shows unique physiochemical properties. Graphene oxide (GO) and silver nanoparticles (AgNPs) were synthesized by modified Hummer's and Chemical reduction methods, respectively. The synthesized nanocomposite was characterized using powder X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The surface morphology of synthesized nanoparticles was studied using scanning electron microscopy and transmission electron microscopy. The thermoluminescence property of the nanocomposite was analyzed by irradiating the samples in gamma radiation at 1 kGy. Electrochemical reversibility of the GO-Ag nanocomposite was examined by cyclic voltammetry. The photocatalytic application of the nanocomposite was studied using degradation of methylene blue dye. Results reveal that doping of AgNPs on the GO surface not only improves its dye degradation property but also enhances its thermoluminescence property. This knowledge will be helpful in determining the antibacterial property of the GO-Ag nanocomposite in the future.

Phyllanthus emblica fruit extract stabilized biogenic silver nanoparticles as a growth promoter of wheat varieties by reducing ROS toxicity.

The present study is focused on the biogenic synthesis of AgNPs (B-AgNPs) using fruit extract of Phyllanthus emblica L. and its effect (0, 5, 10, 25, 50 mg/L concentrations) on early seedling growth of two wheat varieties (HD-2967 and DBW-17). The prepared silver nanoparticles were characterized with several techniques such as UV-Vis spectroscopy, powder X-ray diffraction as well as high-resolution transmission electron microscopy. The capping of AgNPs by phytochemicals was confirmed by Fourier transforms infrared (FT-IR) spectroscopy. B-AgNPs, chemically synthesized AgNPs, chemically synthesized AgNPs+10% fruit extract and AgNO3 salt were compared for phytotoxicity, based on growth parameters, ROS production, cytotoxicity assay and silver accumulation in two wheat varieties (HD-2967 and DBW-17). These effects were more pronounced in the variety HD-2967 over DBW-17 variety at 10 mg/L B-AgNPs exposure. Root cells viability of treated radicles was studied using Evans blue dye assay which suggest that 10 mg/L B-AgNPs was effective in promoting early seedling growth by decreasing ROS toxicity. Lower accumulation of Ag resulting in higher root cell viability than those of chemically synthesized AgNPs treated seedlings. The findings of the present study clearly indicate that phytochemicals capped AgNPs act as a growth promoter at lower concentrations by delivering a potent antioxidant during early seedling growth as compared to chemically synthesized AgNPs treated wheat seedlings.

Enhanced potential of biomimetic, silver nanoparticles functionalized Antheraea mylitta (tasar) silk fibroin nanofibrous mats for skin tissue engineering.

In the present study, we have successfully prepared tasar fibroin nanofibrous mats using 1­butyl­3­methylimidazolium acetate for skin tissue engineering. The prepared tasar nanofibrous mat was further coated by silver nanoparticles (AgNPs) in situ using dandelion (Tridax procumbens) leaf extract. The kinetic of silver nanoparticles formation was studied by UV-VIS spectrophotometer. The prepared silver nanoparticles were further confirmed by XRD and TEM. The coating of tasar nanofibrous mat with silver nanoparticles was confirmed by EDX and EDX mapping techniques. The physical, mechanical, antimicrobial and biological properties of these silver nanoparticles coated tasar nanofibrous mat were determined in order to check its suitability for skin tissue engineering and wound dressing applications.

Dextrose modified flexible tasar and muga fibroin films for wound healing applications.

This paper is focused on preparation and characterization of regenerated muga and tasar fibroin flexible films from cocoon using ionic liquid. These flexible muga and tasar fibroin films were prepared by incorporating dextrose (5 to 15% w/w) as plasticizer. The mechanical, thermal, physical, morphological and biological properties of dextrose plasticized muga and tasar fibroin films were characterized. These plasticized films showed higher elongation at break as well as water holding capacity as compared to the un-plasticized films. The surface roughness and water absorbance capacity of the dextrose plasticized films were higher than un-plasticized films, which results in improved adherence and proliferation of L929 fibroblast cells. Gentamicin loaded plasticized muga and tasar fibroin films showed slightly higher rate of release as compared to un-plasticized films. The biodegradability of dextrose plasticized films was significantly higher as compared to their respective counterpart. The regeneration of flexible muga and tasar silk fibroin films pave the way to expand potential use of non-mulberry in the field of biomedical such as wound dressing.

Fabrication of robust Antheraea assama fibroin nanofibrous mat using ionic liquid for skin tissue engineering.

Electrospinning is an emerging technique used for fabrication of nanofibrous mats for skin tissue engineering applications. The aim of this study centered on fabrication of muga fibroin electrospun mats by using ionic liquid and its characterizations. The muga fibroin extracted from cocoon of Antheraea assama is dissolved in 1-butyl, 3-methyl imidazolium acetate (BMIMAc), a green solvent, to prepare a dope solution for electrospinning. The molecular weight, rheology and structural properties of dope solution are characterized. The process parameters of electrospinning machine such as voltage and concentration of dope solution are varied to obtain nanofibrous mats. The nanofibrous mat having average fiber diameter of 160nm are obtained from 10% w/v concentration of muga fibroin in BMIMAc with an applied voltage of 20KV. The mechanical, structural, physical and thermal properties of muga nanofibrous mat (MNF) are analyzed and compare with muga cast film. The cytocompatibility test is performed using L929 fibroblast cells. It is observed that muga nanofibrous mat support higher growth of fibroblast cells (p<0.05) as compared to muga cast film (MCF). Muga nanofibrous mat and cast film are loaded with gentamycin sulphate. The release rate and antimicrobial efficiency of gentamycin sulphate loaded muga nanofibrous mat are found to be significantly higher (p<0.05) as compared to muga cast film. All these results indicate that muga nanofibrous mat would be a promising material for skin tissue engineering.