In-situ label-free temperature-compensated DNA hybridization detection with a fiber-optic interferometer and a fiber Bragg grating for microfluidic chip.

We demonstrated a temperature-compensated optofluidic DNA biosensor available for microfluidic chip. The optofluidic sensor was composed of an interferometer and a fiber Bragg grating (FBG) by femtosecond laser direct writing micro/nano processing technology. The sensing arm of the interferometer was suspended on the inner wall of the microchannel and could directly interact with the microfluid. With the immobilization of the single stranded probe DNA (pDNA), this optofluidic biosensor could achieve specific detection of single stranded complementary DNA (scDNA). The experimental results indicated that a linear response within 50 nM and the detection limit of 1.87 nM were achieved. In addition, the optofluidic biosensor could simultaneously monitor temperature to avoid temperature fluctuations interfering with the DNA hybridization detection process. And, the optofluidic detection channel could achieve fast sample replacement within 10 s at a flow rate of 2 µL/min and sample consumption only required nanoliters. This optofluidic DNA biosensor had the advantages of label-free, good specificity, dual parameter detection, low sample consumption, fast response, and easy repeatable preparation, which was of great significance for the field of DNA hybridization research and solving the temperature sensitivity problem of biosensors and had good prospects in biological analysis.

Significant enhancement of electron transfer from Shewanella oneidensis using a porous N-doped carbon cloth in a bioelectrochemical system.

Modifying the surface of an anode can improve electron transfer, thus enhancing the performance of the associated bioelectrochemical system. In this study, a porous N-doped carbon cloth electrode was obtained via a simple thermal reduction and etching treatment, and then used as the anode in a bioelectrochemical system. The electrode has a high nitrogen-to­carbon (N/C) ratio (~3.9%) and a large electrochemically active surface area (145.4 cm2, about 4.4 times higher than that of the original carbon cloth), which increases the bacterial attachment and provides more active sites for extracellular electron transfer. Electrochemical characterization reveals that the peak anodic current (0.71 mA) of the porous N-doped carbon cloth electrode in riboflavin is 18 times higher than that of the original carbon cloth electrode (0.04 mA), confirming the presence of more electroactive sites for the redox reaction. We also obtained a maximum current density of 0.29 mA/cm2 during operation of a bioelectrochemical system featuring the porous N-doped carbon cloth electrode, which is 14.5 times higher than that of the original carbon cloth electrode. This result demonstrates that the adoption of our new electrode is a viable strategy for boosting the performance of bioelectrochemical systems.

Construction of fused- and spiro-oxa-[n.2.1] skeletons by a tandem epoxide rearrangement/intramolecular [3+2] cycloaddition of cyclopropanes with carbonyls.

A Lewis acid promoted tandem reaction of epoxide rearrangement and intramolecular [3+2] cycloaddition reaction of cyclopropanes with carbonyls formed by epoxide rearrangement in situ, which were obtained with difficulty by a general method, is reported. A wide variety of fused- and spiro-oxa-[n.2.1] skeletons could be efficiently constructed.

Synthesis of polyisoprene terpenoid dendrons and their applications in oligo(phenylene ethynylene)s as "shells".

The novel double-stage convergent synthesis of a new class of polyisoprene terpenoid (PIPTP) dendrons is described. PIPTP dendrons bear a highly branched aliphatic hydrocarbon skeleton and a hydrophilic hydroxy focal point functionality. These dendrons have the specific formula C((5×2)(G+1)(-5))H((5×2)(G+2)(-8))O, and each dendritic layer is constructed from an isoprene unit. The key branching steps involve a double alkyl-metal addition to an ester functionality, followed by deoxygenation of the resulting tertiary alcohol by triethylsilane and trifluoroacetic acid, then hydrogenation or hydrogenolysis. The dendrons were also attached to oligo(phenylene ethynylene)s (OPEs) so as to function as protective shells to allow fine tuning of the nanoscopic environment around the OPE moiety, and to exert precise control of the packing density and intermolecular interaction between the OPE cores. Fluorescence quantum yield data reveal that the OPE core is better encapsulated by the PIPTP dendrons than by Fréchet dendrons.

Adsorption-desorption properties and characterization of crosslinked Konjac glucomannan-graft-polyacrylamide-co-sodium xanthate.

A new flocculant, based on Konjac-graft-poly (acrylamide)-co-sodium xanthate (CKAX), was synthesized in aqueous solution using epichlorohydrin (ECH) as the cross-linker and ceric ammonium nitrate (CAN) as the initiator. X-ray diffraction indicated the existence of strong interaction between KGM and reactant, including intermolecular and intramolecular hydrogen bonds. Microscopy images exhibited the appropriate pore size and distribution, which might be related to a higher capacity of flocculation and adsorption. Thermo gravimetric analysis showed that the synthetic polymer could improve the thermo-stability of the natural polysaccharides, and there was a positive correlation between polymer residual weight and flocculation. The adsorption and desorption properties for copper ions indicated that the adsorption rate could be described by a pseudo-second-order rate model, and the Freundlich model provides the best fit for the resulting adsorption isotherm. The flocculant can be regenerated in HNO(3) solution.

[Comparison of monolayer wide-edge continuous suture anastomosis with regular interrupted suture anastomosis at esophagogastrostomy for esophageal cancer].

OBJECTIVE: To evaluate the monolayer wide-edge continuous suture anastomosis in order to explore the method to prevent or reduce the frequency of anastomotic fistula and stenosis. METHODS: 936 esophageal cancer patients were divided into two groups: 468 by monolayer wide-edge continuous suture anastomosis with absorbable suture at esophagogastrostomy; while the other 468 by regular interrupted suture anastomosis with silk thread as control. The complication such as anastomotic fistula and stenosis in two groups were compared. RESULTS: In the group treated by monolayer wide-edge continuous suture anastomosis, there were 1 fistula (0.2%) and 1 stenosis (0.2%) versus 8 fistula (1.9%) and 11 stenosis (2.4%) in the control group. There was a statistically significant difference between two guoups was observed (P < 0.05). CONCLUSION: Monolayer wide-edge continuous suture anastomosis at esophagogastrostomy for esophageal cancer patient may effectively prevent or reduce the frequency of anastomotic fistula and stenosis.