Synthesis of thiolated chitosan and preparation nanoparticles with sodium alginate for ocular drug delivery

Purpose: The goal of the present study was to synthesize mucoadhesive polymer -thiolated chitosan (TCS) from chitosan (CS), then prepared CS/TCS-sodium alginate nanoparticles (CS/TCS-SA NPs), determined which was more potential for ocular drug delivery. Methods: A new method for preparing TCS was developed, and the characteristics were determined using Fourier transform infrared spectroscopy and the degree of thiol immobilized was measured by Ellman's reagent. Human corneal epithelium (HCE) cells were incubated with different concentrations of TCS for 48 h to determine the cell viabilities. CS/ TCS-SA NPs were prepared and optimized by a modified ionic gelation method. The particle sizes, zeta potentials, Scanning electron microscopy images, mucoadhesion, in vitro cell uptake and in vivo studies of the two types of NP were compared. Results: The new method enabled a high degree of thiol substitution of TCS, up to 1,411.01±4.02 μmol/g. In vitro cytocompatibility results suggest that TCS is nontoxic. Compared to CS-SA NPs, TCS-SA NPs were more stable, with higher mucoadhesive properties and could deliver greater amounts of drugs into HCE cells in vitro and cornea in vivo. Conclusions: TCS-SA NPs have better delivery capability, suggesting they have good potential for ocular drug delivery applications

Magnetic Luffa-Leaf-Derived Hierarchical Porous Biochar for Efficient Removal of Rhodamine B and Tetracycline Hydrochloride

Luffa leaf (LL) is an agricultural waste produced by loofah. In this work, LL was used as biomass carbon source for biochars for the first time. After carbonization, activation, and chemical co-precipitation treatments, a magnetic lignocellulose-derived hierarchical porous biochar was obtained. The specific surface area and total pore volume were 2565.4 m2/g and 1.4643 cm3/g, and the surface was rich in carbon and oxygen functional groups. The synthetic dye rhodamine B (RhB) and the antibiotic tetracycline hydrochloride (TH) were selected as organic pollutant models to explore the ability to remove organic pollutants, and the results showed good adsorption performances. The maximum adsorption capacities were 1701.7 mg/g for RhB and 1755.9 mg/g for TH, which were higher than most carbon-based adsorbents. After 10 cycles of use, the removal efficiencies were still maintained at more than 70%, showing good stability. This work not only verified the feasibility of lignocellulose LL as a carbon source to prepare biochar but also prepared a magnetic hierarchical porous adsorbent with good performances that can better treat RhB and TH, which provided a new idea and direction for the efficient removal of organic pollutants in water

Numerical Analysis of the Effects of Pulsed Laser Spot Heating Parameters on Brazing of Diamond Tools

A 3D finite element (FE) model is built to numerically analyze heating parameters on temperature during brazing diamond grains by the pulsed laser spot heating. A pulsed Nd:YAG laser is used for experimental validation. The results show that during laser heating, the temperature varies periodically because of the pulsed heat flux. Four key thermal indices, the maximum temperature Tmax, the minimum temperature Tmin, the average temperature Tav and the temperature fluctuation amplitude ΔT are addressed. The primary factor affecting Tmax, ΔT and Tav is the pulse power and on Tmin is the pulse frequency. The secondary effect factor on Tmax, Tav and ΔT is the pulse width and on Tmin is the pulse power. For engineering practice, the order of designing heating parameters is recommended as: pulse power, second frequency and last width

Role of plasma fatty acid in age-related macular degeneration: insights from a mendelian randomization analysis

Abstract Background An imbalance in lipid metabolism has been linked to the development of AMD, but the causal relationship between AMD and plasma fatty acids (FAs) remains controversial. Using a two-sample Mendelian randomization (MR) approach, we sought to evaluate the impact of specific FA plasma levels on the risk of different AMD subtypes. Methods We analysed genome-wide association data of circulating FAs from 115,006 European-descended individuals in the UK Biobank. These data were used in a two-sample MR framework to assess the potential role of circulating FAs in developing wet and dry AMD. Sensitivity analyses were conducted to ensure the robustness of our findings. Additional multivariable and locus-specific MR analyses were conducted to evaluate direct effects of FA on AMD subtypes, minimizing biases from lipoprotein-related traits and triglycerides. Results Mendelian randomization revealed associations of omega-3 was associated with decreased wet (OR 0.78, 95%CI 0.66–0.92) and dry AMD (0.85, 0.74–0.97) risk, showed a protective effect on AMD. Notably, the omega-6 to omega-3 ratio showed potential causal effects on both wet (1.27, 1.03–1.56) and dry AMD (1.18, 1.02–1.37). Multivariable MR suggested that the causal relationship of omega-3, omega-6 to omega-3 ratio on wet AMD persists after conditioning on HDL, LDL and triglycerides, albeit with slightly diminished evidence strength. Locus-specific MR linked to omega-3(FADS1, 0.89, 0.82–0.98; FADS2, 0.88, 0.81–0.96) and omega-6 to omega-3 ratio (FADS1, 1.10, 1.02–1.20; FADS2, 1.11, 1.03–1.20) suggests causal effects of these factors on wet AMD. Conclusions The associations between plasma FA concentrations and AMD, suggest potential causal role of omega-3, and the omega-6 to omega-3 ratio in wet AMD. These results underscore the impact of an imbalanced circulating omega-3 and omega-6 FA ratio on AMD pathophysiology from MR perspective

Interaction between Two Putative Glycosyltransferases Is Required for Glycosylation of a Serine-Rich Streptococcal Adhesin▿

Fap1, a serine-rich glycoprotein, is essential for fimbrial biogenesis and biofilm formation of Streptococcus parasanguinis (formerly S. parasanguis). Fap1-like proteins are conserved in many streptococci and staphylococci and have been implicated in bacterial virulence. Fap1 contains two serine-rich repeat regions that are modified by O-linked glycosylation. A seven-gene cluster has been identified, and this cluster is implicated in Fap1 biogenesis. In this study, we investigated the initial step of Fap1 glycosylation by using a recombinant Fap1 as a model. This recombinant molecule has the same monosaccharide composition profile as the native Fap1 protein. Glycosyl linkage analyses indicated that N-acetylglucosamine (GlcNAc) is among the first group of sugar residues transferred to the Fap1 peptide. Two putative glycosyltransferases, Gtf1 and Gtf2, were essential for the glycosylation of Fap1 with GlcNAc-containing oligosaccharide(s) in both S. parasanguinis as well as in the Fap1 glycosylation system in Escherichia coli. Yeast two-hybrid analysis as well as in vitro and in vivo glutathione S-transferase pull-down assays demonstrated the two putative glycosyltransferases interacted with each other. The interaction domain was mapped to an N-terminal region of Gtf1 that was required for the Fap1 glycosylation. The data in this study suggested that the formation of the Gtf1 and Gtf2 complex was required for the initiation of the Fap1 glycosylation and that the N-terminal region of Gtf1 was necessary

Synthesis of thiolated chitosan and preparation nanoparticles with sodium alginate for ocular drug delivery

Purpose: The goal of the present study was to synthesize mucoadhesive polymer - thiolated chitosan (TCS) from chitosan (CS), then prepared CS/TCS-sodium alginate nanoparticles (CS/TCS-SA NPs), determined which was more potential for ocular drug delivery. Methods: A new method for preparing TCS was developed, and the characteristics were determined using Fourier transform infrared spectroscopy and the degree of thiol immobilized was measured by Ellman's reagent. Human corneal epithelium (HCE) cells were incubated with different concentrations of TCS for 48 h to determine the cell viabilities. CS/TCS-SA NPs were prepared and optimized by a modified ionic gelation method. The particle sizes, zeta potentials, Scanning electron microscopy images, mucoadhesion, in vitro cell uptake and in vivo studies of the two types of NP were compared. Results: The new method enabled a high degree of thiol substitution of TCS, up to 1,411.01 +/- 4.02 mu mol/g. In vitro cytocompatibility results suggest that TCS is nontoxic. Compared to CS-SA NPs, TCS-SA NPs were more stable, with higher mucoadhesive properties and could deliver greater amounts of drugs into HCE cells in vitro and cornea in vivo. Conclusions: TCS-SA NPs have better delivery capability, suggesting they have good potential for ocular drug delivery applications.Science and Technology Planning Projects of Xiamen Science & Technology Bureau, China [502Z20093012, 3502Z20103009

Chemical Conversion Synthesis of ZnS Shell on ZnO Nanowire Arrays: Morphology Evolution and Its Effect on Dye-Sensitized Solar Cell

Heterostructured ZnO/ZnS core/shell nanowire arrays have been successfully fabricated to serve as photoanode for the dye-sensitized solar cells (DSSCs) by a facile two-step approach, combining hydrothermal deposition and liquid-phase chemical conversion process. The morphology evolution of the ZnS coated on the ZnO nanowires and its effect on the performance of the DSSCs were systematically investigated by varying the reaction time during the chemical conversion process. The results show that the compact ZnS shell can effectively promote the photogenerated electrons transfer from the excited dye molecules to the conduction band of the ZnO, simultaneously suppress the recombination for the injected elelctrons from the dye and the redox electrolyte. As reaction time goes by, the surface of the nanowires becomes coarse because of the newly formed ZnS nanoparticles, which will enhance the dye loading, resulting in increment of the short-circuit current density (<i>J</i>_SC) . Open-circuit photovoltage decay measurements also show that the electron lifetime (τ_n) in the ZnO/ZnS core/shell nanostructures can be significantly prolonged because of the lower surface trap density in the ZnO after ZnS coating. For the ZnO/ZnS core/shell nanostructures, the <i>J</i>_SC and η can reach a maximum of 8.38 mA/cm² and 1.92% after 6 h conversion time, corresponding to 12- and 16-fold increments of as-synthesized ZnO, respectively