The objective of the present investigation was to assess the potential of magnesium oxide nanoparticle (MgO NP)-loaded electrospun polycaprolactone (PCL) polymer composites as a bone-soft tissue engineering scaffold. MgO NPs were synthesized using a hydroxide precipitation sol-gel method and characterized using field emission gun-scanning electron microscopy/energy-dispersive x-ray spectroscopy (FEG-SEM/EDS), field emission gun-transmission electron microscopy (FEG-TEM), and x-ray diffraction (XRD) analysis. PCL and MgO-PCL nanocomposite fibers were fabricated using electrospinning with trifluoroethanol as solvent at 19 kV applied voltage and 1.9 ml h flow rate as optimized process parameters, and were characterized by FEG-TEM, FEG-SEM/EDS, XRD, and differential scanning calorimetry analyses. Characterization studies of as-synthesized nanoparticles revealed diffraction peaks indexed to various crystalline planes peculiar to MgO particles with hexagonal and cubical shape, and 40-60 nm size range. Significant improvement in mechanical properties (tensile strength and elastic modulus) of nanocomposites was observed as compared to neat polymer specimens (fourfold and threefold, respectively), due to uniform dispersion of nanofillers along the polymer fiber length. There was a remarkable bioactivity shown by nanocomposite scaffolds in immersion test, as indicated by formation of surface hydroxyapatite layer by the third day of incubation. MgO-loaded electrospun PCL mats showed enhanced in-vitro biological performance with osteoblast-like MG-63 cells in terms of adhesion, proliferation, and marked differentiation marker activity owing to greater surface roughness, nanotopography, and hydrophilicity facilitating higher protein adsorption. In-vivo subcutaneous implantation study in Sprague Dawley rats revealed initial moderate inflammatory tissue response near implant site at the second week timepoint that subsided later (eighth week) with no adverse effect on vital organ functionalities as seen in histopathological analysis supported by serum biochemical and hematological parameters which did not deviate significantly from normal physiological range, indicating good biocompatibility in-vivo. Thus, MgO-PCL nanocomposite electrospun fibers have potential as an efficient scaffold material for bone-soft tissue engineering applications.

A novel composite biomaterial for bone-soft tissue fixation applications was developed. MgO-Silk-PCL, Silk-PCL and MgO-PCL composites were prepared with variable filler concentrations (0, 10, 20 and 30% w/w of MgO nanoparticles and 0%, 5%, 10%, 20% and 30% of degummed silk fiber) in PCL polymer. The highest mechanical properties were obtained with 10% MgO and 20% Silk composite (MSP) wih 1.7× better tensile strength and 7.5× tensile modulus over PCL. It exhibited good cell viability, adhesion and hemocompatibility, increased cell proliferation and differentiation. MgO filler contributed more in increasing tensile strength, whereas silk fiber towards modulus, imparting a synergistic effect on mechanical performance. Prototype bone screws were molded using the MSP composite in a custom-designed mold. It showed significantly increased degradation (2.7 fold after 60 days) in PBS attributable to binary filler phase as compared to PCL. In vivo biosafety studies of MgO-silk-PCL composite screw in SD rats by subcutaneous implantation showed moderate inflammation at 2 weeks which subsided after 4th week. No toxic effect was seen in histopathology of vital organs and in blood parameters. Composite screw showed 2× pull-out strength of PCL in synthetic bone, therefore a potential candidate for bone-soft fixation applications like resorbable orthopedic screws for ACL reconstruction.

Free radical-scavenging antioxidants have the potential as protective agents against various degenerative diseases caused by oxidative damage. Microorganisms are shown to be a promising new source of natural antioxidants. In the present study, supernatant (crude extract) and different solvent extracts (ethyl acetate, n-butanol, dichloromethane) of Saccharomyces boulardii's growth were evaluated for the antioxidant activity using free radical scavenging (1,1-Diphenyl-2-picryl hydrazyl; DPPH) assay, superoxide radical scavenging (nitroblue tetrazolium; NBT) assay, and by estimating total phenolic and flavonoid contents (TPC and TFC). Antioxidative potential of S.boulardii extract was also tested in biological system, i.e. A549 lung cancer cell line using dichlorofluoroscein diacetate (DCF-DA) assay. Organic extracts were further explored by HPLC and mass spectrometry techniques to identify active principles responsible for antioxidant activity. Comparative studies on antiradical ability (DPPH, NBT) revealed that crude extract has the highest activity than its other solvent counterparts as evident by its lower IC50 values and higher TPC and TFC. In vitro studies also showed that S.boulardii extracts effectively quench intracellular reactive oxygen species. Vanillin was identified as one of the contributing antioxidant. It was found that S.boulardii extract is an efficient scavenger of free radicals and can be exploited as a potential new source of natural antioxidants.

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