Beneficial Effects of Fecal Microbiota Transplantation on Ulcerative Colitis in Mice.

BACKGROUND: Ulcerative colitis (UC) is a chronic condition and the most common form of inflammatory bowel disease. The goal of standard treatment is mainly to induce and maintain remission with anti-inflammatory, immunosuppressive agents, and/or colectomy. Fecal microbiota transplantation (FMT) has been used successfully to treat relapsing or refractory Clostridium difficile infection. The alteration of microbiota in mouse models of UC as well as in patients suggested the possibility of treating UC with FMT. AIMS: To study the effects of FMT on dextran sodium sulfate (DSS)-induced UC model in mice. METHODS: Littermates of BALB/c and C57BL/6J were randomized into four groups: normal control , treatment with DSS for 7 days (DSS - FMT), treatment with DSS followed by FMT for another 8 days (DSS + FMT), and treatment with DSS and FMT followed by another 5 days for recovery (remission). Body weight, survival rate, and DAI scores of mice in each group were recorded. Changes in distal colon were studied by histopathology. Alterations of spleen and lamina propria regulatory lymphocytes, major bacterial species in feces and inflammatory cytokines in colon were also studied. RESULTS: C57BL/6J mice experienced more significant weight loss than BALB/c mice after DSS treatment, regardless of whether the two strains of mice were co-housed or not. FMT caused reversal of DAI scores in BALB/c but not in C57BL/6J mice. In BALB/c mice, FMT also reduced colon inflammation that was paralleled by decreased inflammatory cytokine levels, altered bacterial microbiota, and regulatory lymphocyte proportions. CONCLUSIONS: FMT is effective in a mouse model of UC through its modulation on gut microbiota and the host immune system.

Thiolated dendrimers as multi-point binding headgroups for DNA immobilization on gold.

The synthesis of multithiolated DNA molecules that can be used to produce self-assembled monolayers of single-stranded DNA oligonucleotides on gold substrates is described. Generation 3 polyamidoamine (PAMAM) dendrimers were conjugated to DNA oligomers and functionalized with ~30 protected thiol groups. The protected thiol groups-thioacetate groups-allowed the dendrimer-DNA constructs to be stored in a buffer solution for at least 2 months before deprotection without any observable decrease in their ability to assemble into functional layers. The monolayers formed using these multithiolated DNA probe strands demonstrate target capture efficiencies comparable to those of analogous monolayers assembled with DNA functionalized with single thiol groups. A functional advantage of using dendrimer headgroups is the resistance to probe strand loss in prolonged exposure to buffer solutions at a high temperature (95 °C).

NTA directed protein nanopatterning on DNA Origami nanoconstructs.

Precisely patterning proteins and other molecules at the nanoscale is crucial to future biosensing and optoelectronic applications. One- and two-dimensional DNA nanoconstructs have proven to be useful scaffolds for nanopatterning. This paper demonstrates the application of nitrilotriacetic acid (NTA) forming chelate complexes to localize histidine (His) tagged proteins via Ni(2+) ions onto DNA based structures. Particularly, enhanced green fluorescent protein (EGFP) was directed to specific surface locations on a designed DNA Origami nanoconstruct, and the resulting EGFP nanopattern was visualized using atomic force microscopy (AFM).

Fe@Fe2O3 promoted electrochemical mineralization of atrazine via a triazinon ring opening mechanism.

In this study, an electrochemical/electro-Fenton oxidation (EC/EF) system was designed to degrade atrazine, by utilizing boron-doped diamond (BDD) and Fe@Fe2O3 core-shell nanowires loaded active carbon fiber (Fe@Fe2O3/ACF) as the anode and the cathode, respectively. This EC/EF system exhibited much higher degradation rate, decholorination and mineralization efficiency of atrazine than the electrochemical (EC) and electrochemical/traditional electro-Fenton (EC/TEF) oxidation counterpart systems without Fe@Fe2O3 core-shell nanowires. Active species trapping experiment revealed that Fe@Fe2O3 could activate molecular oxygen to produce more OH through Fenton reaction, which favored the atrazine degradation. High performance liquid chromatography, high performance liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry were applied to probe the decomposition and mineralization of atrazine during this novel EC/EF process, which revealed that two intermediates of triazinons (the isomerization of hydroxylated atrazine) were generated during the electrochemical/electro-Fenton oxidation of atrazine in the presence of Fe@Fe2O3 core-shell nanowires. The experimental and theoretical calculation results suggested that atrazine might be degraded via a triazinon ring opening mechanism, while the presence of Fe@Fe2O3 notably accelerated the decholorination process, and produced more hydroxylated products to promote the generation of trazinons and the subsequent ring cleavage as well as the final complete mineralization. This work provides a deep insight into the triazine ring opening mechanism and the design of efficient electrochemical advanced oxidation technologies (EAOTs) for persistent organic pollutant removal.

A novel nitrite biosensor based on the direct electron transfer hemoglobin immobilized in the WO3 nanowires with high length-diameter ratio.

WO3 nanowires (WO3NWs) with high length-diameter ratio have been synthesized through a simple synthetic route without any additive and then used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of WO3NWs were characterized by scanning electron microscopy, transmission electronic microscopy and X-ray diffraction. Spectroscopic and electrochemical results revealed that WO3NWs are an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Meanwhile, due to unique morphology and property of the WO3 nanowires, the direct electron transfer of Hb is facilitated and the prepared biosensors displayed good performance for the detection of nitrite with a wide linear range of 1 to 4200 µM, as well as an extremely low detection limit of 0.28 µM. The WO3 nanowires with high length-diameter ratio could be a promising matrix for the fabrication of mediator-free biosensors, and may find wide potential applications in environmental analysis and biomedical detection.

DNA nanotechnology and its applications in biomedical research.

DNA nanotechnology, which uses DNA as a material to self-assemble designed nanostructures, including DNA 2D arrays, 3D nanostructures, DNA nanotubes and DNA nanomechanical devices, has showed great promise in biomedical applications. Various DNA nanostructures have been used for protein characterization, enzyme assembly, biosensing, drug delivery and biomimetic assemblies. In this review, we will present recent advances of DNA nanotechnology and its applications in biomedical research field.