Unravelling the Photoelectrochemical Water Splitting of Nanometer-Thick Carbon Nitride Layer.

Matching the thickness of the graphitic carbon nitride (CN) nanolayer with the charge diffusion length is expected to compensate for the poor intrinsic conductivity and charge recombination in CN for photoelectrochemical cells (PEC). Herein, the compact CN nanolayer with tunable thickness is in situ coated on carbon fibers. The compact packing along with good contact with the substrate improves the electron transport and alleviates the charge recombination. The PEC investigation shows CN nanolayer of 93 nm-thick yields an optimum photocurrent of 116 µA cm-2 at 1.23 V versus RHE, comparable to most micrometer-thick CN layers, with a low onset potential of 0.2 V in 1 m KOH under 1 sun illumination. This optimum performance suggests the electron diffusion length matches with the thickness of the CN nanolayer. Further deposition of NiFe-layered double hydroxide enhanced the surface water oxidation kinetics, delivering an improved photocurrent of 210 µA cm-2 with IPCE of 12.8% at 400 nm. The CN nanolayer also shows extended potential in PEC organic synthesis. This work experimentally reveals the PEC behavior of the nanometer-thick CN layer, providing new insights into CN in the application of energy and environment-related fields.

Synthesis of globotriose-modified peptides for the preparation of a colorimetric biosensor to detect Shiga toxins.

Globotriose (Gal-α1, 4-Gal-ß1, 4-Glc) is involved in binding with Shiga toxins (Stxs) produced by Shigella dysenteriae and certain pathogenic Escherichia coli strains which could cause severe gastroenteritis and hemolytic uremic syndrome (HUS). Thus, this trisaccharide group and its derivatives provide potentials in the development of carbohydrate-based diagnostic and therapeutic reagents against bacterial infection. Instead of the tedious chemical synthesis of globotriose or its glycoconjugates, we reported a multi-step (step-wise) enzymatic synthesis system containing glucosyltransferase (ApNGT, E.C. 4.3.3.5), ß-1, 4-galactosyltransferase (LgtB, E.C. 2.4.1.22) and α-1, 4-galactosyltransferase (LgtC, E.C. 2.4.1.44) to produce globotriose-containing glycopeptides. In addition, based on the specific binding between Stxs and globotriose, a cost-efficient, convenient, ultra-sensitive and specific colorimetric biosensor was further constructed to detect Stxs using glycoconjugated Au@Fe-TFPA-COP (globotriose@Au@Fe-TFPA-COP) as a nanoenzyme catalyst. We estimate that this method conveniently applied in the detection of Stx-producing bacteria and associated infectious diseases.

Chemoenzymatic Labeling Pathogens Containing Terminal N-Acetylneuraminic Acid-α(2-3)-Galactose Glycans.

The N-acetylneuraminic acid-α(2-3)-galactose epitope is often located at the nonreducing terminal ends of glycans on the envelopes of many pathogens, and it is believed that this structure mimics a host's oligosaccharide so as to circumvent and/or counteract the host's immune responses. A chemoenzymatic method for the rapid and sensitive detection of N-acetylneuraminic acid-α(2-3)-galactose has been built, so we planned to examine whether the chemoenzymatic method could be applied on the detection of N-acetylneuraminic acid-α(2-3)-galactose on pathogens. Our results revealed that the chemoenzymatic method was rapid and sensitive for labeling live or dead Gram-positive Streptococcus agalactiae A909 and Gram-negative Campylobacter jejuni MK104 with N-acetylneuraminic acid-α(2-3)-galactose. This study suggested that the chemoenzymatic method was a new strategy for labeling pathogens and had potential for the diagnosis of or therapeutics for pathogenic infection.

Substrate specificity of the galactokinase from the human gut symbiont Akkermansia muciniphila ATCC BAA-835.

Galactokinases, which catalyze the phosphorylation of galactose and possible other monosaccharides, can provide an activated sugar donor to synthesize sugar-containing molecules. In this study, a novel galactokinase from human gut symbiont Akkermansia muciniphila ATCC BAA-835 (GalKAmu) was expressed and characterized. GalKAmu displayed broad substrate tolerance, with catalytic activity towards Gal (100 %), GalN (100 %), GalA (20.2 %), Glc (52.5 %), GlcNAc (15.5 %), Xyl (<5%), ManNAc (58 %), ManF (37.4 %) and l-Glc (80 %). Most interestingly, this was the first GalK isoform which can tolerate ManNAc. Thus, our characterization of GalKAmu broadens the substrate selection of galactokinases.

Probing peptide substrate specificities of N-glycosyltranferase isoforms from different bacterial species.

N-glycosyltransferase (NGT) is responsible for transferring hexose monosaccharides to the asparagine side chain of proteins and polypeptides in the consensus sequon (N-(X≠P)-T/S) with nucleotide-activated sugars as donor substrates. Here, we expressed and purified four different N-glycosyltransferases derived from diverse bacteria, including Actinobacillus pleuropneumoniae, Aggregatibacter aphrophilus, Kingella kingae and Bibersteinia trehalosi, and measured their catalytic activities of four synthesized peptides via in vitro glycosylation assays. RP-HPLC and mass spectrometry were used to identify and quantify the glycopeptide formation by distinct NGT isoforms. We then analyzed and compared the glycosylation efficiencies of different peptides for these four NGT isoforms, which showed distinct substrate selectivities. We sought to probe peptide specificities among various NGT isoforms, which could broaden the application of NGT-catalyzed N-glycosylation of a variety of therapeutic proteins.

VEGF overexpression is associated with optic nerve involvement and differentiation of retinoblastoma: A PRISMA-compliant meta-analysis.

BACKGROUND: Vascular endothelial growth factor (VEGF) plays an important role in the pathogenesis of cancer. Although numerous studies have investigated the association between VEGF expression and pathogenesis of retinoblastoma, the results remained inconsistent. To illuminate the association, we performed a meta-analysis study. METHODS: According to the PRISMA guideline, eligible studies were searched in the Medicine, Embase, Web of Science, Chinese National Knowledge Infrastructure, and Wanfang databases. Stata 14.0 software was used to calculate the relevant statistical parameters. RESULTS: Seventeen studies with 296 controls and 470 patients with retinoblastoma were included from 17 eligible literatures. Overall, significant association between VEGF overexpression and susceptibility of retinoblastoma was observed in Chinese population (odds ratio [OR] = 21.67, 95% confidence interval [CI] = 13.96-33.62). Subgroup analysis based on control sample type showed that VEGF overexpression was significantly associated with the risk of retinoblastoma (Normal retina tissue, OR = 23.97, 95% CI = 9.67-59.42; retinoblastoma adjacent tissue, OR = 20.85, 95% CI = 12.64-34.37). Significant associations of VEGF overexpression with optic nerve involvement and differentiation of retinoblastoma were found (Optic nerve involvement, OR = 6.90, 95% CI = 4.01-11.88; Differentiation, OR = 0.18, 95% CI = 0.12-0.28). In addition, only 1 study was included to analyze the role of VEGF protein expression in the prognosis of retinoblastoma, and the result showed that VEGF expression was significantly associated with the prognosis of retinoblastoma, which should be verified in the future studies. CONCLUSIONS: Our findings demonstrated that VEGF overexpression was significantly associated with the risk of retinoblastoma. Besides, the results suggested that VEGF overexpression might have a crucial effect on the optic nerve involvement and differentiation of retinoblastoma.

Long noncoding RNA BDNF-AS is a potential biomarker and regulates cancer development in human retinoblastoma.

BACKGROUND: Long non-coding RNAs (lncRNA) have been shown to play important roles in human cancer. We examined expression, prognostic potential and functional roles of lncRNA, brain-derived neurotrophic factor antisense (BDNF-AS) in human retinoblastoma (RB). METHODS: BDNF-AS expression in RB tumors was characterized according to the clinicopathological parameters of patients. BDNF-AS mRNA level was compared between RB tumors and normal retinas, as well as RB cell lines and normal retinal epithelial cells. RB patients' overall survival was compared between those with low and high BDNF-AS tumor expressions. Statistical analysis was performed to examine the independence of BDNF-AS being cancer biomarker in RB. In Y79 and WERI-Rb-1 cells, BDNF-AS was upregulated. It's effect on cancer proliferation, migration and cell-cycle transition were assessed. RESULTS: BDNF-AS is downregulated in RB tumors and cell lines. Low BDNF-AS expression in RB tumors is correlated with patients' advanced clinical stage and tumor differentiation status. Low BDNF-AS expression is associated with shorter overall survival and may be acting as an independent marker in RB. In Y79 and WERI-Rb-1 cells, forced overexpression of BDNF-AS inhibited cancer proliferation and migration. It also induced cell-cycle arrest at G0/G1 phase by downregulating CDC42, Cyclin E and BDNF. CONCLUSION: BDNF-AS is lowly expressed, and may be used as a prognostic biomarker in RB. Upregulating BDNF-AS has inhibitory effect on RB development, probably through the suppression of cell-cycle transition.

Comparison of bilateral lateral rectus recession and unilateral recession resection for basic type intermittent exotropia in children.

AIMS: To compare surgical outcome of bilateral lateral rectus recession (BLR-rec) and unilateral lateral rectus recession combined with medial rectus resection (R&R) for the basic type of intermittent exotropia (IXT) in children. METHODS: Eighty-five consecutive patients aged 3-15 years old with the basic type IXT who underwent surgery and had a minimum postoperative follow-up of 6 months were retrospectively reviewed. Thirty-eight patients underwent BLR-rec and 47 underwent R&R. Successful surgical alignment was defined as esophoria/tropia ≤5 PD (prism dioptres) to exophoria/tropia ≤8 PD in primary gaze while viewing distant or near targets. RESULTS: After a mean follow-up of 14.8 ± 9.5 months, the subjects who had undergone R&R surgery had a significantly higher success rate than those who had BLR-rec surgery (85.1% vs 65.8%, p=0.037). The undercorrection rate was significantly lower in the R&R group than in the BLR-rec group (6.4% vs 23.7%, p=0.023) and there was no significant difference in the overcorrection rate between the two groups (10.5% vs 8.5%, p=1.000). CONCLUSIONS: R&R is more effective than BLR-rec surgery in the long term for the basic type IXT in children.