Corrosion Resistance of Fe-Based Amorphous Films Prepared by the Radio Frequency Magnetron Sputter Method.

Amorphous thin films can be applied to increase the anti-corrosion ability of critical components. Atomized FeCrNiMoCSiB powders were hot-pressed into a disc target for R. F. magnetron sputtering on a 316L substrate to upgrade its corrosion resistance. The XRD spectrum confirmed that the film deposited by R. F. magnetron sputtering was amorphous. The corrosion resistance of the amorphous film was evaluated in a 1 M HCl solution with potentiodynamic polarization tests, and the results were contrasted with those of a high-velocity oxy-fuel (HVOF) coating and 316L, IN 600, and C 276 alloys. The results indicated that the film hardness and elastic modulus, as measured using a nanoindenter, were 11.1 and 182 GPa, respectively. The principal stresses in two normal directions of the amorphous film were about 60 MPa and in tension. The corrosion resistance of the amorphous film was much greater than that of the other samples, which showed a broad passivation region, even in a 1 M HCl solution. Although the amorphous film showed high corrosion resistance, the original pinholes in the film were weak sites to initiate corrosion pits. After polarization tests, large, deep trenches were seen in the corroded 316L substrate; numerous fine patches in the IN 600 alloy and grain boundary corrosion in the C276 alloy were observed.

Consecutive Hypoxia Decreases Expression of NOTCH3, HEY1, CC10, and FOXJ1 via NKX2-1 Downregulation and Intermittent Hypoxia-Reoxygenation Increases Expression of BMP4, NOTCH1, MKI67, OCT4, and MUC5AC via HIF1A Upregulation in Human Bronchial Epithelial Cells.

Previous studies have shown that the experimental models of hypoxia-reoxygenation (H/R) mimics the physiological conditions of ischemia-reperfusion and induce oxidative stress and injury in various types of organs, tissues, and cells, both in vivo and in vitro, including human lung adenocarcinoma epithelial cells. Nonetheless, it had not been reported whether H/R affected proliferation, apoptosis, and expression of stem/progenitor cell markers in the bronchial epithelial cells. In this study, we investigated differential effects of consecutive hypoxia and intermittent 24/24-h cycles of H/R on human bronchial epithelial (HBE) cells derived from the same-race and age-matched healthy subjects (i.e., NHBE) and subjects with chronic obstructive pulmonary disease (COPD) (i.e., DHBE). To analyze gene/protein expression during differentiation, both the NHBE and DHBE cells at the 2nd passage were cultured at the air-liquid interface (ALI) in the differentiation medium under normoxia for 3 days, followed by either culturing under hypoxia (1% O2) for consecutively 9 days and then returning to normoxia for another 9 days, or culturing under 24/24-h cycles of H/R (i.e., 24 h of 1% O2 followed by 24 h of 21% O2, repetitively) for 18 days in total, so that all differentiating HBE cells were exposed to hypoxia for a total of 9 days. In both the normal and diseased HBE cells, intermittent H/R significantly increased HIF1A, BMP4, NOTCH1, MKI67, OCT4, and MUC5AC expression, while consecutive hypoxia significantly decreased NKX2-1, NOTCH3, HEY1, CC10, and FOXJ1 expression. Inhibition of HIF1A or NKX2-1 expression by siRNA transfection respectively decreased BMP4/NOTCH1/MKI67/OCT4/MUC5AC and NOTCH3/HEY1/CC10/FOXJ1 expression in the HBE cells cultured under intermittent H/R to the same levels under normoxia. Overexpression of NKX2-1 via cDNA transfection caused more than 2.8-fold increases in NOTCH3, HEY1, and FOXJ1 mRNA levels in the HBE cells cultured under consecutive hypoxia compared to the levels under normoxia. Taken together, our results show for the first time that consecutive hypoxia decreased expression of the co-regulated gene module NOTCH3/HEY1/CC10 and the ciliogenesis-inducing transcription factor gene FOXJ1 via NKX2-1 mRNA downregulation, while intermittent H/R increased expression of the co-regulated gene module BMP4/NOTCH1/MKI67/OCT4 and the predominant airway mucin gene MUC5AC via HIF1A mRNA upregulation.

Cationic solid lipid nanoparticles with cholesterol-mediated surface layer for transporting saquinavir to the brain.

Cholesterol-mediated cationic solid lipid nanoparticles (CSLNs) were formulated with esterquat 1 (EQ 1) and stearylamine as positively charged external layers on hydrophobic internal cores of cacao butter. These CSLNs were employed to deliver saquinavir (SQV) to the brain. The permeability of SQV across the blood-brain barrier (BBB) using SQV-loaded CSLNs (SQV-CSLNs) was estimated with an in vitro model of a monolayer of human brain-microvascular endothelial cells (HBMECs) regulated by human astrocytes. The results revealed that the average diameter of SQV-CSLNs diminished when the weight percentage of cholesterol and EQ 1 increased. The morphological images indicated a uniform size of SQV-CSLNs with compact lipid structure. In addition, an increasing weight percentage of cholesterol and EQ 1 enhanced the zeta potential of SQV-CSLNs. The fluorescent staining demonstrated that HBMECs could internalize SQV-CSLNs. An increase in the weight percentage of cholesterol and EQ 1 also promoted the uptake of SQV-CSLNs by HBMECs. Moreover, a high content of cholesterol and EQ 1 in SQV-CSLNs increased the BBB permeability of SQV. The cholesterol-mediated SQV-CSLNs can be an efficacious drug delivery system for brain-targeting delivery of antiviral agents.

Guided differentiation of induced pluripotent stem cells into neuronal lineage in alginate-chitosan-gelatin hydrogels with surface neuron growth factor.

The understanding of differentiating induced pluripotent stem (iPS) cells in porous biomaterials is a critical challenge in recent biotechnological development. This study presents the investigation on the differentiation of iPS cells toward neurons in biomedical scaffolds containing alginate, chitosan, and gelatin with grafted neuron growth factor (NGF). Alginate-chitosan-gelatin scaffolds were prepared by particulate leaching method using polystyrene (PS) microspheres as porogen. In addition, the neuronal differentiation of iPS cells in the constructs was identified by immunochemical staining. The morphological studies demonstrated that an increase in the concentration of PS microspheres from 0.5 to 0.75 g/mL improved the pore regularity in alginate-chitosan-gelatin hydrogels. The effect of composition on the differentiation of iPS cells into neuronal lineage was in the order where alginate:chitosan:gelatin=1:1:3>2:1:2>1:1:1. Moreover, an increase in the concentration of NGF promoted the neuronal production from iPS cells in cultivated constructs. Alginate-chitosan-gelatin scaffolds with surface NGF can guide the differentiation of iPS cells for regenerating neurons.

Cationic solid lipid nanoparticles with primary and quaternary amines for release of saquinavir and biocompatibility with endothelia.

Application of cationic solid lipid nanoparticles (CSLNs), comprising complex internal matrix and lipid-regulated external surface, is an intriguing issue in current bionanotechnology. This study presents dissolution kinetics of saquinavir (SQV) from CSLNs with cholesterol-mediated esterquat 1 (EQ 1) and biocompatibility of SQV-loaded CSLNs with human brain-microvascular endothelial cells (HBMECs). CSLNs with SQV in lipid cores containing cholesterol were dissolved and incubated with HBMECs. The results revealed that an increase in the weight percentage of EQ 1 reduced the entrapment efficiency of SQV. In addition, the entrapment efficiency of SQV enhanced, when the weight percentage of cholesterol increased from 0% to 25% (w/w). The reverse was true when cholesterol increased from 0% to 75% (w/w). The dissolution profiles demonstrated that the mediation of cholesterol favored the sustained release of SQV. When the weight percentage of EQ 1 increased, the viability of HBMECs enhanced. An increase in the weight percentage of cholesterol, however, reduced the viability of HBMECs. The innovated CSLNs containing cholesterol can be effective in controlled release of SQV without inducing significant endothelial toxicity.

Cartilage regeneration by culturing chondrocytes in scaffolds grafted with TATVHL peptide.

Formation of neocartilage is a critical issue in contemporary regenerative medicine. This study presents the generation of tissue engineering cartilage in TATVHL peptide-grafted scaffolds. Bovine knee chondrocytes were seeded in TATVHL peptide-grafted scaffolds and cultured in a spinner bioreactor. The results revealed that surface TATVHL peptide enhanced the adhesion of bovine knee chondrocytes in scaffolds. However, an increase in the concentration of TATVHL peptide in scaffolds (up to 20 µg/mL) did not cause an evident variation in the cell viability. Surface TATVHL peptide was effective in promoting the quantity of cartilaginous components in constructs after dynamic cultivation. Biochemical assay, scanning electron microscope images, and histological staining demonstrated that surface TATVHL peptide accelerated the proliferation of bovine knee chondrocytes in constructs. In addition, the secretion of glycosaminoglycans and production of collagen in TATVHL peptide-grafted constructs were faster than those in TATVHL peptide-free constructs. TATVHL peptide can be a promising bioactive molecule to improve chondrogenesis in porous biomaterials.

Targeting nevirapine delivery across human brain microvascular endothelial cells using transferrin-grafted poly(lactide-co-glycolide) nanoparticles.

AIMS: Poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) were grafted with transferrin (Tf) to enhance the transport of nevirapine (NVP) across human brain microvascular endothelial cells (HBMECs). METHODS: NVP-loaded PLGA NPs with surface-grafting Tf (Tf/NVP-PLGA NPs) were incubated with HBMECs and immunochemical staining characterized Tf receptors (TfRs). RESULTS: The polydispersity index of Tf/NVP-PLGA NPs was lower than 0.008. The entrapment efficiency of NVP and loading efficiency of Tf was 20-75% and 15-80%, respectively. Tf slightly retarded the release of NVP from PLGA. Dioctadecyldimethylammonium bromide (DODAB)-stabilized Tf/NVP-PLGA NPs reduced the viability of HBMECs to 70-75%. The secretion of TNF-α was inhibited by Tf and stimulated by DODAB. The permeability of NVP across HBMECs reached maxima at 67% DODAB and 0.1-0.2% Tf. An increase in the concentration of Tf enhanced the uptake of Tf/NVP-PLGA NPs via a TfR-mediated mechanism. CONCLUSION: Tf/NVP-PLGA NPs are efficacious carriers in targeting delivery across HBMECs for viral therapy.

Surface modification with peptide for enhancing chondrocyte adhesion and cartilage regeneration in porous scaffolds.

The present study presents the regeneration of cartilage in hybrid scaffolds comprising polyethylene oxide (PEO) and chitosan with surface CDPGYIGSR. This surface peptide was grafted via crosslinking onto the scaffolds. The pores in the scaffolds were interconnected and uniformly distributed with an average diameter about 200-250 µm. A high weight percentage of PEO in the matrix yielded a rugged topography of the pore surfaces. The adhesion of bovine knee chondrocytes (BKCs) in the peptide-grafted scaffolds was more efficient than that in the peptide-free scaffolds. In addition, the constructs with surface peptide could stimulate chondrogenesis with enhanced quantities of BKCs, glycosaminoglycans (GAGs), and collagen over cultivation. The histological staining of the proliferated BKCs and secreted GAGs indicated that the surface peptide favored the production of neocartilage in the constructs. Moreover, the immunochemical staining against type II collagen demonstrated the maintenance of phenotypic chondeocytes on the peptide-grafted surfaces. The peptide-grafted PEO/chitosan scaffolds can be applied to the treatment for injured cartilage in preclinical trials.

Electrophoresis of human brain microvascular endothelial cells with uptake of cationic solid lipid nanoparticles: effect of surfactant composition.

This study analyzes the effects of Tween 80 and Span 20 on the electrical interaction between cationic solid lipid nanoparticles (CSLNs) and human brain microvascular endothelial cells (HBMECs). Electrophoretic mobility, zeta potential and fixed charge density of CSLNs and HBMECs with uptake of CSLNs were also investigated. The results revealed that a higher molar ratio of Tween 80 yielded smaller CSLNs, higher charge of CSLNs and larger electrical attraction energy between CSLNs and HBMECs. On the contrary, a decrease in the molar ratio of Tween 80 enhanced the absolute values of electrophoretic mobility and zeta potential of CSLNs-incorporating HBMECs. In addition, a higher concentration of CSLNs in the dispersion medium led to lower charge of CSLNs-incorporating HBMECs. An increased concentration of glutamate from 1 to 2mg/mL enhanced the absolute values of electrophoretic properties of CSLNs-incorporating HBMECs. In the case of increasing concentration of glutamate, pure Tween 80 was stronger in charge enhancement than pure Span 20.