A PEDOT: PSS/GO fiber microelectrode fabricated by microfluidic spinning for dopamine detection in human serum and PC12 cells.

Rapid and accurate in situ determination of dopamine is of great significance in the study of neurological diseases. In this work, poly (3,4-ethylenedioxythiophene): poly (styrenesulfonic acid) (PEDOT: PSS)/graphene oxide (GO) fibers were fabricated by an effective method based on microfluidic wet spinning technology. The composite microfibers with stratified and dense arrangement were continuously prepared by injecting PEDOT: PSS and GO dispersion solutions into a microfluidic chip. PEDOT: PSS/GO fiber microelectrodes with high electrochemical activity and enhanced electrochemical oxidation activity of dopamine were constructed by controlling the structure composition of the microfibers with varying flow rate. The fabricated fiber microelectrode had a low detection limit (4.56 nM) and wide detection range (0.01-8.0 µM) for dopamine detection with excellent stability, repeatability, and reproducibility. In addition, the PEDOT: PSS/GO fiber microelectrode prepared was successfully used for the detection of dopamine in human serum and PC12 cells. The strategy for the fabrication of multi-component fiber microelectrodes is a new and effective approach for monitoring the intercellular neurotransmitter dopamine and has high potential as an implantable neural microelectrode.

Metabolomic analysis and pathway profiling of paramylon production in Euglena gracilis grown on different carbon sources.

Paramylon (ß-1,3-glucan) produced by Euglena gracilis displays antioxidant, antitumor, and hypolipidaemic functions. The biological properties of paramylon production by E. gracilis can be understood by elucidating the metabolic changes within the algae. In this study, the carbon sources in AF-6 medium were replaced with glucose, sodium acetate, glycerol, or ethanol, and the paramylon yield was measured. Adding 0.1260 g/L glucose to the culture medium resulted in the highest paramylon yield of 70.48 %. The changes in metabolic pathways in E. gracilis grown on glucose were assessed via non-targeted metabolomics analysis using ultra-high-performance liquid chromatography coupled to high-resolution quadrupole-Orbitrap mass spectrometry. We found that glucose, as a carbon source, regulated some differentially expressed metabolites, including l-glutamic acid, γ-aminobutyric acid (GABA), and l-aspartic acid. Pathway analysis using the Kyoto Encyclopedia of Genes and Genomes further showed that glucose regulated the carbon and nitrogen balance through the GABA shunt, which enhanced photosynthesis, regulated the flux of carbon and nitrogen into the tricarboxylic acid cycle, promoted glucose uptake, and increased the accumulation of paramylon. This study provides new insights into E. gracilis metabolism during paramylon synthesis.

Clarity improvement of the discoloration boundary and detection of Hg2+ ions by using a polystyrene nanoparticle-modified paper-based microdevice.

Distance-based microfluidic paper-based analytical devices (µPADs) can be used to calculate the analyte content by reading the length of the discolored area in the channel. A blurred discoloration boundary is difficult to distinguish, resulting in reading errors. In this study, we constructed a µPAD modified with carboxyl-containing polystyrene nanoparticles (PS-µPAD) to improve the discoloration-boundary clarity. The filling of the pores of the fibers with the deposited polystyrene nanoparticles (PS NPs) caused a decrease in the paper porosity, resulting in a flow delay. Meanwhile, the carboxyl groups carried by PS NPs were able to form hydrogen bonds with hydroxyl-containing compounds FLPI, a Hg2+ probe, and the two factors acted synergistically to fix the FLPI to react in situ, raising the discoloration-boundary clarity. Compared with the unmodified µPAD, the detection of Hg2+ ions using the PS-µPAD still had a good linear relationship. Importantly, the color-depth difference inside and outside the discoloration boundary improved by about four times and showed excellent reproducibility in different populations. The method was simple and easy to expand, thereby providing an idea for more widespread application of distance-based µPADs.

Dual-channel fluorescent signal readout strategy for cysteine sensing.

Cysteine (Cys) is a biological thiol. Aberrant changes in thiol levels are associated with the development and pathogenesis of various diseases, including liver damage, Alzheimer's disease, weakness, and cardiovascular diseases. Therefore, thiol detection in biological samples has great importance in health monitoring and disease prediction. In this study, we developed a ratiometric fluorescence nanosensor combined with carbon dots (CDs)-doped mesoporous silica and fluorescein-based fluorescent probes loaded in pores for Cys detection. The nanosensor emitted fluorescence at 450 nm upon excitation at 370 nm. In the presence of Cys, the fluorescence emission from the probe could be selectively enhanced, whereas that from CDs could be changed. Thus, a ratiometric fluorescent sensor was developed. This sensor can eliminate the potential influence of background fluorescence and other analyte-independent external environmental factors. The nanosensor was utilized to monitor Cys levels in human serum, and satisfactory results were obtained. Results indicated that the nanosensor can be utilized as an excellent fluorescent nanocomposite material in practical biological applications.

A new effective scaffold to facilitate peripheral nerve regeneration: chitosan tube coated with maggot homogenate product.

Recent efforts in scientific research in the field of peripheral nerve regeneration have been directed towards the development of artificial nerve guides. Chitosan tubes applied as a biocompatible and biodegradable bilateral guide for nerve repair is a hot spot in research to date. In previous study, we have found the homogenate product from disinfected maggot larvae can promote wound nerve regeneration and neuropeptides release. Wound nerves belong to the peripheral nerve system. We thus hypothesize that maggot homogenate product use as an external layer outside the chitosan tube will be an effective therapy to facilitate peripheral nerve regeneration.

Copper-taurine (CT): a potential organic compound to facilitate infected wound healing.

Taurine plays various important roles in a large number of physiological and pathological conditions in human body, such as the cytoprotective functions, antioxidant, anti-inflammatory and anti-apoptosis effects. Copper demonstrates a critical effect in the processes of wound healing, including induction of endothelial growth factor, angiogenesis, antimicrobial potency and expression and stabilization of extracellular matrix. Both copper and taurine are effective in accelerating wound healing, but it was rarely reported about the formation of copper complexes of taurine and the effect of the compound in wound healing. Generally speaking, to human body, organic compound could provide a better bioavailability than the inorganic ones. We thus hypothesize that taurine combined with copper would be a new therapeutic candidate for infected wound healing. We name the new compound copper-taurine (CT). Copper-taurine (CT) added into the wound dressings would not only reduce the risk of wound infection, but, more importantly, would stimulate wound repair directly. The sustained release of copper and taurine from the wound dressings into the wound site would together facilitate the wound healing more potently.