Field-Effect Sensors Using Biomaterials for Chemical Sensing.

After millions of years of evolution, biological chemical sensing systems (i.e., olfactory and taste systems) have become very powerful natural systems which show extreme high performances in detecting and discriminating various chemical substances. Creating field-effect sensors using biomaterials that are able to detect specific target chemical substances with high sensitivity would have broad applications in many areas, ranging from biomedicine and environments to the food industry, but this has proved extremely challenging. Over decades of intense research, field-effect sensors using biomaterials for chemical sensing have achieved significant progress and have shown promising prospects and potential applications. This review will summarize the most recent advances in the development of field-effect sensors using biomaterials for chemical sensing with an emphasis on those using functional biomaterials as sensing elements such as olfactory and taste cells and receptors. Firstly, unique principles and approaches for the development of these field-effect sensors using biomaterials will be introduced. Then, the major types of field-effect sensors using biomaterials will be presented, which includes field-effect transistor (FET), light-addressable potentiometric sensor (LAPS), and capacitive electrolyte-insulator-semiconductor (EIS) sensors. Finally, the current limitations, main challenges and future trends of field-effect sensors using biomaterials for chemical sensing will be proposed and discussed.

Optimization of sodium percarbonate pretreatment for improving 2,3-butanediol production from corncob.

Sodium percarbonate (SP), a kind of alkaline strong oxidant, was applied to corncob pretreatment. The optimized pretreatment conditions were at 4% (w/v) SP concentration with solid-to-liquid (SLR) ratio of 1:10 treating for 4 hr at 60°C. This pretreatment resulted in 91.06% of cellulose and 84.08% of hemicellulose recoveries with 34.09% of lignin removal in corncob. The reducing sugar yield from SP-pretreated corncob was 0.56 g/g after 72 hr of enzymatic hydrolysis, 1.75-folds higher than that from raw corncob. 2,3-butanediol production by Enterobacer cloacae in simultaneous saccharification fermentation was 29.18 g/L using SP-pretreated corncob as a substrate, which was 11.12 times of that using raw corncob. Scanning electron microscope, X-ray diffraction, and Fourier transform infrared spectra analysis indicated that physical characteristics, crystallinity, and structure of corncob had changed obviously after SP pretreatment. This simple and novel pretreatment method was effective for delignification and carbohydrate retention in microbial production of 2,3-butanediol from lignocellulose biomass.

Effect of ß-mannanase domain from Trichoderma reesei on its biochemical characters and synergistic hydrolysis of sugarcane bagasse.

BACKGROUND: ß-mannanase is a key enzyme for hydrolyzing mannan, a major constituent of hemicellulose, which is the second most abundant polysaccharide in nature. Different structural domains greatly affect its biochemical characters and catalytic efficiency. However, the effects of linker and carbohydrate-binding module (CBM) on ß-mannanase from Trichoderma reesei (Man1) have not yet been fully described. The present study aimed to determine the influence of different domains on the expression efficiency, biochemical characteristics and hemicellulosic deconstruction of Man1. RESULTS: The expression efficiency was improved after truncating CBM. Activities of Man1 and Man1ΔCBM (CBM) in the culture supernatant after 168 h of induction were 34.5 and 42.9 IU mL-1 , although a value of only 0.36 IU mL-1 was detected for Man1ΔLCBM (lacking CBM and linker). Man1 showed higher thermostability than Man1ΔCBM at low temperature, whereas Man1ΔCBM had a higher specificity for galactomannan (Km = 2.5 mg mL-1 ) than Man1 (Km = 4.0 mg mL-1 ). Both Man1 and Man1ΔCBM could synergistically improve the hydrolysis of cellulose, galactomannan and pretreated sugarcane bagasse, with a 10-30% improvement of the reducing sugar yield. CONCLUSION: Linker and CBM domains were vital for mannanase activity and expression efficiency. CBM affected the thermostability and adsorption ability of Man1. The results obtained in the present study should help guide the rational design and directional modification of Man with respect to improving its catalytic efficiency. © 2017 Society of Chemical Industry.

Zeolitic imidazolate framework-8/bacterial cellulose composites for iodine loading and their antibacterial performance.

Bacterial cellulose (BC), produced by bacteria and fungi, is a promising material in the biomedical field. However, non-antibacterial activity limits its broad applications. Herein, antibacterial composites (BC/ZIF-8-iodine) were prepared by loading iodine into zeolitic imidazolate framework-8 (ZIF-8) modified BC (BC/ZIF-8). BC/ZIF-8-iodine was well characterized by SEM, XRD, FTIR, XPS, Raman and contact angle analyses. The increase of ZIF-8 content augmented the loading capacity of iodine in BC/ZIF-8-iodine. Meanwhile, the adsorbed iodine can be released from BC/ZIF-8-iodine composites, following the Higuchi equation. A reduced sublimation of iodine was observed in BC/ZIF-8-iodine composites, indicating their good iodine preservation ability. BC/ZIF-8-iodine composites exhibited strong antibacterial activity towards Escherichia coli, Staphylococcus aureus and Candida albicans. XPS and Raman analyses indicated that the adsorbed iodine of BC/ZIF-8-iodine composites was in the form of I3-. The expected iodine loading, release and preservation behaviors of BC/ZIF-8-iodine composites ensure their antibacterial performance and suggest potential clinical applications.

Neuronal adhesion and growth on nanopatterned EA5-POPC synthetic membranes.

Biomimetic membranes create opportunities for various applications, including the possibility of replacing interacting cells in a cell-cell contact. Here we have fractionated synthetic membranes using metal nano-grid structures where EphrinA5 (EA5), a neuronal adhesion promoter, was anchored via its Fc domain (immunoglobulin G (IgG)-domain). FRAP experiments were performed to check the confinement of the synthetic membrane within these nano-structures. Rat cortical primary neurons were cultured and live cell imaging techniques were used to monitor the neuronal interaction with these fractionated synthetic membranes. Computational imaging analysis of the corresponding images elucidated interesting details of the cellular behavior. The phenotypic cellular response on these nano-membrane fractions was found to be similar to that on non-fractionated synthetic membranes indicating that although the number of focal adhesion points was low (due to the reduced EA5 number) in the nano-sized membrane patches perhaps some other factors like metal grid boundaries might be playing a role in rendering the similarity.

A metagenomic study of the gut microbiome in Behcet's disease.

BACKGROUND: Behcet's disease (BD) is a recalcitrant, multisystemic inflammatory disease that can lead to irreversible blindness. Microbial agents have been considered to contribute to the pathogenesis of this disease, but the underlying mechanisms remain unclear. In this study, we investigated the association of gut microbiome composition with BD as well as its possible roles in the development of this disease. METHODS: Fecal and saliva samples were collected from 32 active BD patients and 74 healthy controls. DNA extracted from fecal samples was subjected to metagenomic analysis, whereas DNA extracted from saliva samples was subjected to 16S rRNA gene sequencing analysis. The results were used to compare the composition and biological function of the microbiome between patients and healthy controls. Lastly, transplantation of pooled fecal samples from active BD patients into B10RIII mice undergoing experimental autoimmune uveitis (EAU) was performed to determine the causal relationship between the gut microbiome and BD. RESULTS: Fecal samples from active BD patients were shown to be enriched in Bilophila spp., a sulfate-reducing bacteria (SRB) and several opportunistic pathogens (e.g., Parabacteroides spp. and Paraprevotella spp.) along with a lower level of butyrate-producing bacteria (BPB) Clostridium spp. and methanogens (Methanoculleus spp. Methanomethylophilus spp.). Analysis of microbial functions revealed that capsular polysaccharide transport system, oxidation-reduction process, type III, and type IV secretion systems were also increased in active BD patients. Network analysis showed that the BD-enriched SRB and opportunistic pathogens were positively correlated with each other, but they were negatively associated with the BPB and methanogens. Animal experiments revealed that fecal microbiota transplantation with feces from BD patients significantly exacerbated EAU activity and increased the production of inflammatory cytokines including IL-17 and IFN-γ. CONCLUSIONS: Our findings revealed that BD is associated with considerable gut microbiome changes, which is corroborated by a mouse study of fecal microbiota transplants. A model explaining the association of the gut microbiome composition with BD pathogenesis is proposed.

Optimization of headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry for detecting methoxyphenolic compounds in pu-erh tea.

A method based on headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was developed for the analysis of volatile methoxyphenolic compounds in pu-erh tea. Six fibers with different polarities were initially evaluated. The 75 µm carboxen/polydimethylsiloxane fiber exhibited the highest extraction efficiency and was selected for further optimization. A Plackett-Burman design was used to screen for the brewing proportion of tea and water, amount of pu-erh tea, ionic strength, extraction time, extraction temperature, desorption time, rate of agitation, and equilibrium time. A Box-Behnken design was then applied to optimize the significant factors. Under optimal conditions, the proposed method affords a wide range of linearity, high linear regression coefficients (0.996-0.999), less than 9.0% repeatability of relative standard deviation, and limits of detection ranging from 2.31 to 21.80 ng/g. The proposed method has satisfactory accuracy, with recoveries of 79.08-113.9%. This method was successfully applied for the analysis of pu-erh tea samples.