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Graphical abstract: Experimental workflow for the reducing sugar production

In most chemical reactions, reaction rates increase with increasing reactant concentrations. In this study, we report an unusual catalytic oxidation reaction with a negative reaction order, in which the reactant concentration inversely affected the oxidation rate. In the reaction, trypan blue was oxidized by hydrogen peroxide with copper-triglycine as a catalyst. Under a strong alkaline condition, the reaction rate was inversely proportional to the hydrogen peroxide concentration (i.e., the reaction rate was faster when the hydrogen peroxide concentration was lower). Without the copper-triglycine catalyst, the phenomenon did not happen. A possible explanation was that hydrogen peroxide competed with the reactive species of the catalyst and slowed down the reaction. This phenomenon had an important implication in advanced oxidation processes for wastewater treatments. To achieve a faster oxidation rate of trypan blue, one should add hydrogen peroxide slowly to keep its concentration low at all times. On the basis of this principle, we developed a continuous microdroplet injection process to deliver the hydrogen peroxide solution as droplets. This process was faster and more efficient than a batch process for the degradation of trypan blue.

Millifluidic devices decorated with enzymes have been used for enzymatic reactions in continuous processes, but low enzymatic activity and enzyme leaching remain as challenges. Herein, we develop a strategy to embed cross-linked enzyme aggregates (CLEAs) on the surfaces of millifluidic devices to achieve higher enzymatic activity and better stability. Catalase was chosen as a model enzyme to degrade H2O2in wastewater samples. First, CLEA of catalase (153 ± 10 nm) was formed by simultaneous precipitation and cross-linking with 25.0 wt % acetonitrile containing 0.025 wt % glutaraldehyde in a millifluidic device. To immobilize CLEA, we first swell a piece of plastic tubing by using 5.0 wt % acetonitrile and then immerse it in an aqueous solution with 5.0 wt % (3-aminopropyl)triethoxysilane (APTES) and 5.0 wt % dextran polyaldehyde (DPA) subsequently. After CLEA is absorbed inside the expanded polymer network of the tubing, the tubing is tightened by using a vacuum to secure the immobilized CLEA. The millifluidic device decorated with CLEA of catalase has total activity of 660 U for degradation of H2O2, and it shows good stability under a flow rate of 200 μL/min. The tubing can be used to degrade 0.1 wt % H2O2solution continuously for 3 h or remove 2 wt % residual H2O2in wastewater for 2 h. The technique is general enough and can be applied to other types of enzymes for continuous enzymatic reactions.

Immobilized enzymes can be used to catalyze biochemical reactions in a batch process, however, it is more difficult to use them in a continuous process. Herein, we develop an enzyme immobilization technique for flexible tubing surfaces, which can be used to catalyze biochemical reactions in a continuous process. In this technique, the tubing is first treated with (3-aminopropyl)triethoxysilane at 50 °C and baked at 100 °C in vacuum to form a network of reactive amine functional group on the inner tubing surface. Subsequently, dextran polyaldehyde, a polymeric cross-linker, is used to immobilize crude protease extract and catalase for hydrolyzing casein and degrading H2O2, respectively, in a continuous process. The immobilized proteases are highly stable even after a long-term storage at 4 °C. After 12 weeks of storage, 90% of the original protease activity can be preserved. Meanwhile, the immobilized catalase is able to degrade 0.1% H2O2solution flowing at 5 μL/min. The immobilization technique is potentially useful for bioassays and industrial wastewater treatments when continuous processes are preferred.

This paper is to elucidate the correlation between different symptoms of UTUC and the clinicopathological characteristics and prognosis. The clinicopathological data of 700 consecutive patients with UTUC who were treated with radical nephroureterectomy were reviewed, and symptoms were categorized into three groups: S1-no direct symptoms, S2-local symptoms (including hematuria and flank pain) and S3-systemic symptoms. We found that the distributions of patients in the S1, S2 and S3 groups were 96 (13.7%), 601 (85.9%) and 3 (0.4%), respectively, and most patients in S1 were incidentally found to have abnormal findings on ultrasound during regular health examination. Altogether, 534 patients (76.3%) presented with gross hematuria, and 111 (15.9%) presented with flank pain. Patients in S1 had a higher rate of hydronephrosis (p < 0.001), ureteral tumors (p < 0.001), worse pre-operative renal function (p = 0.020) and lower tumor stage (p = 0.038). The presence of hematuria was significantly related with renal pelvic tumors (p < 0.001), higher pre-operative eGFR (p = 0.047), papillary tumor architecture (p = 0.005) and less hydronephrosis (p < 0.001); and the presentation of flank pain was correlated with older age (p = 0.008), ureteral location (p < 0.001), hydronephrosis (p < 0.001), sessile architecture (p < 0.001) and higher tumor grade (p = 0.003). The presence of hematuria or flank pain also failed to reach significance as an independent prognostic factor. In conclusion, asymptomatic UTUC patients are featured for more hydronephrosis and lower tumor stage, while patients who presented with flank pain had a higher risk of sessile architecture and higher tumor grade. Regular health examinations might play a useful role in the early detection of UTUC patients with no symptoms.

This paper is to elucidate the correlation between different symptoms of UTUC and the clinicopathological characteristics and prognosis. The clinicopathological data of 700 consecutive patients with UTUC who were treated with radical nephroureterectomy were reviewed, and symptoms were categorized into three groups: S1‐no direct symptoms, S2‐local symptoms (including hematuria and flank pain) and S3‐systemic symptoms. We found that the distributions of patients in the S1, S2 and S3 groups were 96 (13.7%), 601 (85.9%) and 3 (0.4%), respectively, and most patients in S1 were incidentally found to have abnormal findings on ultrasound during regular health examination. Altogether, 534 patients (76.3%) presented with gross hematuria, and 111 (15.9%) presented with flank pain. Patients in S1 had a higher rate of hydronephrosis (p < 0.001), ureteral tumors (p < 0.001), worse pre‐operative renal function (p = 0.020) and lower tumor stage (p = 0.038). The presence of hematuria was significantly related with renal pelvic tumors (p < 0.001), higher pre‐operative eGFR (p = 0.047), papillary tumor architecture (p = 0.005) and less hydronephrosis (p < 0.001); and the presentation of flank pain was correlated with older age (p = 0.008), ureteral location (p < 0.001), hydronephrosis (p < 0.001), sessile architecture (p < 0.001) and higher tumor grade (p = 0.003). The presence of hematuria or flank pain also failed to reach significance as an independent prognostic factor. In conclusion, asymptomatic UTUC patients are featured for more hydronephrosis and lower tumor stage, while patients who presented with flank pain had a higher risk of sessile architecture and higher tumor grade. Regular health examinations might play a useful role in the early detection of UTUC patients with no symptoms.

Electrospun polymer-liquid crystal (PLC) fibers have potential applications such as wearable sensors and adaptive textiles because of their rapid response and high flexibility. However, existing PLC fibers only have a narrow responsive range and poor resistance to heat and chemicals. Herein, a new type of PLC fiber is prepared by using a coaxial electrospinning process. The core solution is 4′-pentyl-4-biphenylcarbonitrile (5CB), and the sheath solution is a mixture containing 13 wt % PVP and 10 wt % reactive mesogen (RM). After UV exposure of the fibers, 5CB in the core and RM diffusing from the core are cross-linked into an LC polymer. The fibers have a highly uniform morphology with an average diameter of 3.2 ± 0.5 μm, and mesogens inside the fibers align unidirectionally with the long axis of the fibers. The fibers show a broad phase-transition temperature range between 13.5 and 155.5 °C and have a response time of less than 10 s. The temperature range can also be controlled by adjusting components in the electrospun fibers and UV exposure time. The core-sheath fibers prepared in such a manner exhibit excellent heat and chemical resistance with reversible optical responses. Moreover, when the fibers are exposed to volatile organic compounds (VOCs) such as toluene, the fibers show a rapid optical response to toluene vapor within 25 s. This study demonstrates that the fibers are potentially useful for preparing flexible temperature and chemical sensors.

The major predisposing factors of developing oral cancer include smoking, alcohol drinking, and betel quid chewing. Betel quid chewing could cause the abrasion and damage of oral mucosa by crude fibers, chemical insults by additive slaked lime, and arecoline from areca nut. These would lead to the local consequence of oral submucosal fibrosis, which is regarded clinically as a precancer lesion and a major cause of trismus. In addition, the components and additives in betel quid contain chemical toxins and carcinogens, which would further affect the oral mucosa and gradually develop a malignancy. Following literature review, aside from having a greater total tumor burden and more local diseases in the oral cavity and digestive tract, patients with betel quid-related oral cancer also have more systemic diseases from metabolic syndrome, hypertension, cardiovascular disease, type II diabetes mellitus, and obesity than those without this habit. In conclusion, those patients who have the history of smoking, alcohol drinking, and betel quid chewing would present much more unique clinical characteristics than those who only have a history of smoking and alcohol drinking. More attention should therefore be paid to pretreatment evaluation, treatment strategy, and posttreatment follow-up among betel quid chewers.

Background:This retrospective cohort study was to assess the prognostic value of preoperative albumin-to-alkaline phosphatase ratio (AAPR) on survival outcome for patients with locally advanced oral squamous cell carcinoma (LAOSCC). Methods:A total of 250 patients with LAOSCC receiving upfront radical surgery at a single institute from January 2008 to December 2017 were enrolled. The primary endpoint was the survival predictability of preoperative AAPR on the 5-year overall survival (OS), cancer-specific survival (CSS), and disease-free survival (DFS). Cox proportional hazards model was used for survival analysis. The X-tile software was used to estimate the optimal cut-off value of preoperative AAPR on survival prediction. A predictive nomogram incorporating the clinicopathological factors on OS was further generated. Results:The 5-year OS, CSS, and DFS rates were 68.6%, 79.7%, and 61.7%, respectively. The optimal cut-off of preoperative AAPR to predict the 5-year OS was observed to be 0.51. For those with preoperative AAPR≧0.51, the 5-year OS, CSS, and DFS were statistically significantly superior to those with preoperative AAPR<0.51 (OS: 76.1% vs 48.5%, P< .001; CSS: 84.3% vs 66.4%, P= .005; DFS: 68.9% vs 42.6%, P< .001). In Cox model, we observed that preoperative AAPR<0.51 was a significantly negative prognosticator of OS (HR: 2.22, 95% CI: 1.466-3.361, P< .001), CSS (HR: 2.037, 95% CI: 1.16-3.578, P=.013), and DFS (HR: 1.756, 95% CI: 1.075-2.868, P=.025). After adding the variable of preoperative AAPR, the c-index of the predictive nomogram incorporating assorted clinicopathological factors increases from 0.663 to 0.692 for OS. Conclusion:Our results suggest that preoperative AAPR serves as an independent survival predictor for patients with LAOSCC. The nomogram incorporating preoperative AAPR and various clinicopathological features may be a convenient tool to estimate the mortality risk for patients with LAOSCC.

In this paper, we report a method of detecting DNA targets hybridized to a solid surface by using liquid crystals (LC). The detection principle is based on different interference colors of LC supported on surfaces decorated with single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA). However, the contrast between the ssDNA and dsDNA is not obvious, unless DNA-streptavidin complexes are introduced to the dsDNA to increase the surface mass density. Two different approaches of introducing streptavidin to the system are studied and compared. We find that by premixing the biotin-labeled DNA targets with streptavidin prior to the DNA hybridization, branched-streptavidin complexes are formed and clear LC signal can be observed. This LC-based DNA detection principle represents an important step toward the development of a simple, instrument- and fluorophore-free DNA detection method.

In this paper, we report the role of surfactants in minimizing nonspecific protein adsorption in liquid crystal (LC)-based immunoassays in which LC is used as a readout system. Among all surfactants tested, only nonionic surfactant such as Tween 20 can effectively reduce the nonspecific protein adsorption, while maintaining the selectivity of the LC-based immunoassay. We also show that to minimize nonspecific protein adsorption, Tween 20 can be added directly into the antibody solution to a final concentration of 0.8 mM. After the addition of Tween 20, better correlations between the antibody concentrations and the interference colors of LCs can therefore be obtained. For example, when Cy3 antibiotin was used, black, yellow, red, and green interference colors correspond to a concentration of 5, 25, 50, and 100 μg/mL, respectively. This feature gives LC immunoassay a unique advantage over the fluorescence-based immunoassay.

A liquid crystal (LC)‐based pH sensor for real‐time monitoring of changes in localized pH values near a solid surface is reported, along with its application for the detection of enzymatic activities. It is found that 4‐cyano‐4′‐pentylbiphenyl (5CB), when doped with 4′‐pentyl‐biphenyl‐4‐carboxylic acid (PBA), shows a bright‐to‐dark optical response to a very small change in pH (from 6.9 to 7.0). The pH‐driven optical response can be explained by using orientational transitions of 5CB induced by the protonation and deprotonation of PBA at the aqueous/LC interface. Because of its high pH sensitivity, the LC‐based sensor is further exploited for monitoring local pH changes resulting from enzymatic reactions. As a proof of concept, the hydrolysis of penicillin G by surface‐immobilized penicillinase is monitored using the system, even when the concentration of penicillin G is as low as 1 nM. This type of LC‐based sensor may find potential utilities in high‐throughput screening of enzyme substrates and enzyme inhibitors.

Here, a novel method of immobilizing proteins with well‐defined orientation directly on liquid crystal surfaces that allow subsequent real‐time imaging of specific protein–protein binding events on these surfaces is reported. Self‐assembly of nitrilotriacetic acid terminated amphiphiles loaded with Ni2+ions at aqueous‐liquid crystal interface creates a surface capable of immobilizing histidine‐tagged ubiquitin through complex formation between Ni2+and histidine. When these surfaces containing immobilized histidine‐tagged ubiquitin are exposed to anti‐ubiquitin antibody, the spatial and temporal of specific protein–protein binding events trigger orientational transitions of liquid crystals. As a result, sharp liquid crystal optical switching from dark to bright can readily be observed under polarized lighting. The protein–protein binding can be observed within seconds and only requires nanogram quantities of proteins. This work demonstrates a simple strategy to immobilize proteins with well‐defined orientation on liquid crystal surfaces for real‐time and label‐free detection of specific protein–protein binding events, which may find use in biomedical diagnostics.

A new air‐supported liquid crystal (LC) system for analyzing interfacial phenomena that occur based on the molecular interaction between LCs and adsorbed molecules of interest at the aqueous/LC interface is reported. Compared with existing LC‐based detection systems, the miniature system reported here requires less sample and involves simpler preparation. Using this system, the enzymatic hydrolysis of various phospholipases such as phospholipase A2(PLA2), phospholipase C (PLC) and phospholipase D (PLD) are characterized. The hydrolysis of phospholipid monolayers self‐assembled at aqueous/LC interface induces an orientational response from the LCs. As a result, an optical signal that reflects the spatial and temporal distribution of phospholipids during the enzymatic reaction can be generated in a real‐time manner. When well‐known phospholipase inhibitors are introduced together with respective phospholipases, no orientational response of LCs is observed. In the case of inhibitors MJ33 and compound 48/80, cross‐inhibitions among phospholipases are also observed. This work demonstrates that the air‐supported LC system provides a facile label‐free assay for characterizing phospholipase activities and for screening enzyme inhibitors. It could potentially be useful for different high throughput and cost‐effective enzyme screening assays.

We report a method of controlling the conformations of immobilized triglycine and improving its selectivity for copper ion by mixing equal molar of triglycine and copper ion during the immobilization step. Our attenuated total reflectance-Fourier transformation infrared (ATR-FTIR) spectroscopy shows that, when triglycine molecules are immobilized in the presence of copper ions, both amide I and amide II bands of triglycine increase, which can be attributed to the conformational change of triglycine from a random coil to a loop structure. Interestingly, even after copper ion is removed, the loop structure is still maintained, possibly due to the formation of intermolecular hydrogen bonds between adjacent triglycine molecules. Immobilized triglycine molecules with a loop structure show excellent complexation capability and selectivity for copper ion. Even in the presence of 100× other metal ions such as zinc and nickel, surface immobilized triglycine with a loop structure still preferentially binds to copper ions. No zinc or nickel ions can be detected on the surface.

An engineered B. subtilis1A1 strain (BsADH2) expressing a secondary alcohol dehydrogenase (CpSADH) was co-cultured with C. beijerinckiiG117 under an aerobic condition. During the fermentation on glucose, B. subtilisBsADH2 depleted oxygen in culture media completely and created an anaerobic environment for C. beijerinckiiG117, an obligate anaerobe, to grow. Meanwhile, lactate produced by B. subtilisBsADH2 was re-assimilated by C. beijerinckiiG117. In return, acetone produced by C. beijerinckiiG117 was reduced into isopropanol by B. subtilisBsADH2 via expressing the CpSADH, which helped maintain the redox balance of the engineered B. subtilis. In the symbiotic system consisting of two strains, 1.7 ​g/L of acetone, 4.8 ​g/L of butanol, and 0.9 ​g/L of isopropanol (with an isopropanol/acetone ratio of 0.53) was produced from 60 ​g/L of glucose. This symbiotic system also worked when oxygen was supplied to the culture, although less isopropanol was produced (0.9 ​g/L of acetone, 4.9 ​g/L of butanol, and 0.2 ​g/L of isopropanol). The isopropanol titer was increased substantially to 2.5 ​g/L when we increased the inoculum size of B. subtilisBsADH2 and optimized other process parameters. With the Bacillus-Clostridiumco-culture, switching from the original acetone-butanol (AB) fermentation to an aerobic acetone-butanol-isopropanol (ABI) fermentation can be easily achieved without genetic engineering of Clostridium. This strategy of employing a recombinant Bacillusto co-culture with Clostridiumshould be potentially useful to modify traditional acetone-butanol-ethanol fermentation for the production of other value-added chemicals.

In this Letter, we report a principle of discriminating dialdehydes from monoaldehydes by using optical responses of liquid crystals (LCs) triggered by a surface reaction between aldehydes and surface amine groups. When a solid surface is decorated with a mixture of long hydrocarbons and primary amines, a surface reaction between dialdehydes and the surface amines generates an aldehyde-terminated surface (which can be tested by using a triglycine−copper complex as an aldehyde marker). This type of surface is able to trigger an ordering transition of 5CB supported on the surface. In contrast, the surface reaction between monoaldehydes and the surface amines leads to a hydrocarbon-terminated surface which does not influence the orientations of 5CB on the surface. Because LCs are birefringent materials, the changes of orientations can cause distinct optical textures visible to the naked eye. The methodology reported herein provides a simple optical method of detecting and distinguishing dialdehydes from monoaldehydes with high sensitivity (∼10 M for glutaraldehyde and phthaldialdehyde) and specificity.