WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY
·
2022
·Vol. 38
·期 5
·1-8
·
IF 4.253
Li Yudi,Chen Guiying,Ge Fanglan,Dang Ting,Ren Yao,Zeng Bei,Li Wei
γ-aminobutyric acid (GABA) has various physiological functions and is widely used in medicine, food, and other fields. Glutamate decarboxylase (GAD) is a key enzyme that catalyzes the decarboxylation of L-glutamate to synthesize GABA. However, the industrial application of microorganism-derived GAD is limited by its rapid loss of enzymatic activity with pH approaching neutrality. In this study, a novel glutamate decarboxylase, GAD MSM, from Mycobacterium smegmatis was overexpressed and purified. On the basis of homologous modeling and substrate molecular docking, several GAD MSM mutants were constructed, and their enzymatic properties were analyzed. The results showed that the optimal pH of wild-type GAD MSM is 5.4; at pH 6.2, 22.8% enzymatic activity was retained. The T211I replacement in GAD and C-terminal deletion mutant GAD MSMΔC showed relatively high catalytic activity in a pH range of 5.0–7.0. The V max and K m values of GAD MSMΔC were 14.69 and 5.70, respectively, at pH 5.5, and 9.87 and 6.17, respectively, at pH 7.0. Compared with the wild-type GAD, GAD MSMΔC maintained higher affinity and enzymatic activity of the substrate, maintaining 78.5% of the highest enzymatic activity even at pH 7.0, which is the highest reported activity retention for GAD under neutral pH condition. Therefore, GAD MSMΔC can be used for the transformation of high-yielding strains and industrial production of GABA.
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MARINE POLLUTION BULLETIN
·
2022
·
IF 7.001
Wang Li,Bo Zu,Qingwei Yang,Junwen An,Jiawen Li
Nanoplastics (NPs) are widely found in the environment and can act as a vector for various toxic substances and promote their diffusion and bioenrichment, but the underlying mechanisms are largely unknown. Here, the adsorption characteristics of bisphenol A (BPA) onto NPs were explored. The results show that the adsorption of BPA on NPs was dominated by saturated single-layer adsorption and affected by both intra-particle diffusion and liquid film diffusion. Electrostatic interaction, π–π interaction, and hydrophobic effects played key roles in adsorption. In addition, the introduction of electrolytes inhibited the adsorption of BPA onto NPs. Interestingly, the introduction of suspended sediment promoted the formation of heterogeneous aggregates of NPs-SS, thereby reducing the adsorption capacity, indicating that aggregation may play an important role in the adsorption behavior of NPs. Overall, our results provide new insights into the adsorption behavior of BPA on NPs and the underlying mechanisms under different environmental conditions.
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Signal Transduction and Targeted Therapy
·
2022
·Vol. 7
·期 1
·1-9
·
IF 38.104
Cao Changyu,Zhang Tingbo,Yang Nan,Niu Xianghong,Zhou Zhaobo,Wang Jinlan,Yang Dongliang,Chen Peng,Zhong Liping,Dong Xiaochen,Zhao Yongxiang
The current feasibility of nanocatalysts in clinical anti-infection therapy, especially for drug-resistant bacteria infection is extremely restrained because of the insufficient reactive oxygen generation. Herein, a novel Ag/Bi 2 MoO 6 (Ag/BMO) nanozyme optimized by charge separation engineering with photoactivated sustainable peroxidase-mimicking activities and NIR-II photodynamic performance was synthesized by solvothermal reaction and photoreduction. The Ag/BMO nanozyme held satisfactory bactericidal performance against methicillin-resistant Staphylococcus aureus (MRSA) (~99.9%). The excellent antibacterial performance of Ag/BMO NPs was ascribed to the corporation of peroxidase-like activity, NIR-II photodynamic behavior, and acidity-enhanced release of Ag + . As revealed by theoretical calculations, the introduction of Ag to BMO made it easier to separate photo-triggered electron-hole pairs for ROS production. And the conduction and valence band potentials of Ag/BMO NPs were favorable for the reduction of O 2 to ·O 2 − . Under 1064 nm laser irradiation, the electron transfer to BMO was beneficial to the reversible change of Mo 5+ /Mo 6+ , further improving the peroxidase-like catalytic activity and NIR-II photodynamic performance based on the Russell mechanism. In vivo, the Ag/BMO NPs exhibited promising therapeutic effects towards MRSA-infected wounds. This study enriches the nanozyme research and proves that nanozymes can be rationally optimized by charge separation engineering strategy.
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CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Xuesong Cai,Xiudi Xiao,Guizhang Sheng,Jieyuan Zheng,Yajie Zhao,Gang Xu
In wet-chemistry processes, pH value is an important parameter that can be used to control the microstructures of the as-grown nanostructures . In this work, W 18 O 49 nanowires with crystalline@amorphous core-shell structures were synthesized by controlling the pH of the precursor solutions in a hydrothermal reaction . Due to surface functionalization by ethylene glycol (EG) groups, the hydrothermally grown W 18 O 49 nanowires could be easily dispersed in aqueous environment, thus enabling the fabrication of electrochromic thin films of W 18 O 49 nanowires by a simple spray-drying process. The optimized W 18 O 49 nanowire films showed a large optical modulation (ΔT) of 81.1% at 633 nm, short response time (coloring/bleaching time τ c /τ b = 7.9 s/3.9 s), good cycle stability (ΔT retention was 84.5% after 1000 cycles), and the excellent memory effect (the color withstood for 36000s after turning off the voltage). Furthermore, the electrochromic device (ECD) (4 × 4 cm 2 ) based on the W 18 O 49 nanowires exhibits a large optical modulation of 56.6%, short response time (τ c = 7.6 s, τ b = 2.7 s), and superior coloration efficiency (CE) of 64 cm 2 C −1 . Finally, by simply amplifying the developed processes, a large-area electrochromic device (10 × 10 cm 2 ) was successfully prepared, which implies the possibility of large-area spraying process for practical applications.
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JOURNAL OF MOLECULAR LIQUIDS
·
2022
·
IF 6.633
Xufa He,Kangle Jia,Longfei Yu,Huanling Li,Jinlan Xin,Xiaoshan Zheng,Junhua Ning,Haifu Wu,Linjia Huang,Wu Wen
Pickering emulsions that are stabilized by organic particles that are issued from renewable sources have attracted considerable attention. However, developing green and robust Pickering emulsions of various types via simple methods has always been an important challenge. Herein, a rosin derivative, namely, maleopimaric acid (MPA), which has three carboxylic acid groups, is used to stabilize Pickering emulsions. Various types of gel-like Pickering emulsions can be obtained by adjusting the wettability of rigid MPA by changing the pH, such as water (W) in oil (O), O/W, double, and multiple emulsions. With increasing MPA concentration and volume fraction of the oil phase, phase inversion occurs from W/O to O/W and from O/W to W/O, respectively. The formed gel-like Pickering emulsions have excellent external stimulus and mechanical stabilities and can withstand high temperature (70 °C), freeze-thaw treatment and high centrifugal forces. These outstanding properties are due to the stable interfacial film and the network structure that are formed by the self-assembly of MPA with heterogeneous ionization degrees. This study provides a natural rosin-based solid stabilizer with adjustable wettability and further advances the design of stable Pickering emulsions with various structural features based on practical application needs.
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MOLECULES
·
2022
·Vol. 27
·期 2
·520
·
IF 4.927
Le Xu,Xi Liu,Jiao Jia,Hao Wu,Juan Xie,Yongtang Jia
Accurately and sensitively sensing and monitoring the pH in the environment is a key fundamental issue for human health. Nanomaterial and nanotechnology combined with fluorescent materials can be emerged as excellent possible methods to develop high-performance sensing membranes and help monitor pH. Herein, a series of fluorescent nanofiber membranes (NFMs) containing poly-1,8-naphthimide derivative-3-[dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]azaniumyl]propane-1-sulfonate (PNI-SBMA) are fabricated by electrospinning the solution of PNI-SBMA blended with poly(vinyl alcohol) (PVA). The surfactant-like functionalities in side chains of PNI-SBMA endow the NFMs with outstanding hydrophilicity, and the naphthimide derivatives are sensitive to pH by photoinduced electron transfer effect, which contribute to highly efficient pH fluorescence sensing applications of NFMs. Specifically, the PNI-SBMA/PVA NFM with a ratio of 1:9 (NFM2) shows high sensitivity and good cyclability to pH. This work demonstrates an effective strategy to realize a fluorescent sensor NFM that has a fast and sensitive response to pH, which will benefit its application of pH sensor monitoring in the water treatment process.Keywords:electrospinning;nanofibers;fluorescence;sensors;pH
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Pharmaceutics
·
2022
·Vol. 14
·期 3
·535
·
IF 6.525
Huiru Zhu,Li Kong,Xu Zhu,Tingting Ran,Xiaojuan Ji
A high incidence of restenosis has been reported at the site of inflammation following angioplasty and stent implantation. The anti-proliferative drug paclitaxel (PTX) could help to reduce inflammation and restenosis; however, it has poor water solubility and serious adverse side effects at high doses. Given the presence of metabolic acidosis at the site of inflammation, we hypothesized that nanoparticles that are responsive to low pH could precisely release the loaded drug at the target site. We successfully constructed pH-responsive poly(D, L-lactic-co-glycolic acid) (PLGA) nanoparticles loaded with PTX and NaHCO3as a pH-sensitive therapeutic agent (PTX-NaHCO3-PLGA NPs). The NPs exhibited remarkable pH sensitivity and a good safety profile both in vitro in rat vascular smooth muscle cells and in vivo in Sprague Dawley rats after tail vein injection. In the rat model, the PTX-NaHCO3-PLGA NPs treatment group showed suppressed intimal proliferation following balloon-induced carotid artery injury compared with that of the saline-treated control. Overall, these results demonstrate that our newly developed pH-responsive nanodrug delivery platform has the potential to effectively inhibit restenosis.Keywords:vascular restenosis;pH-responsive nanoparticles;sodium bicarbonate;paclitaxel;drug delivery
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DYES AND PIGMENTS
·
2022
·
IF 5.122
Shanshan Li,Jiaqi Zhang,Yanrong Li,Yang Xu
Synthesis of nano coordination polymers (NCPs) with dual fluorescence emission is highly desirable, but is still a challenge for further ratiometric sensing applications. In this work, porphyrin-based NCPs with dual fluorescence emission were prepared via a solvothermal process using branched polyethyleneimine (PEI) as passivation agent for ratiometric fluorescent sensing of pH and copper ion . Two NCPs@PEI can be obtained with different fluorescence emissions due to regulation of reaction time. NCPs@PEI-1 exhibited a good fluorescence response to pH with a calibration function of l g ( I 655 / I 477 ) = 0.2750 ( p H ) − 2.2989 (R 2 = 0.977), derived from protonation and deprotonation of pyrrolic nitrogen and amino groups in the NCPs@PEI. Moreover, by exploiting the electron transfer between Cu 2+ and nitrogen in porphyrin , NCPs@PEI-1 was used as sensor for detecting Cu 2+ with a function of y = − 0.0074 x + 0.5990 (R 2 = 0.999) and the limit of detection was calculated to be 136 nM based on 3σ/κ. These NCPs with tunable emission, excellent fluorescence, and “two in one” characteristic for Cu 2+ and pH sensing highlights NCPs@PEI as a potential fluorescent probe for multi-target analysis.
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COLLOID AND POLYMER SCIENCE
·
2023
·Vol. 301
·期 8
·989-999
·
IF 2.4
Hu Tao,Xu Weichuan,Li Dong,Wang Song,Wang Yuxiang,Wu Caijin,Tan Liqiang
Extensive use of Al 2 O 3 nanoparticles in consumer and industrial products has led to concerns about their potential environmental impacts in the recent years. In most studies concerning Al 2 O 3 aggregation and disaggregation, more was to consider the single factor that influences their environmental behaviors. Understanding the combined abiotic factors that influence the fate, transport, and stability of nanoparticles in a complex aquatic system has become extremely important. Here, we reported and analyzed the major abiotic factors such as typical solution pH, electrolyte cations in different valences (Na + and Ca 2+ ), and the presence of humic acid (HA) that influence the stability, aggregation, and disaggregation behaviors of Al 2 O 3 nanoparticles in a complex aquatic system. Dynamic light scattering technique combined with fluorescence spectroscopic analysis was used to explore the aggregation mechanisms. Experimental results indicated that Al 2 O 3 nanoparticle stability was mainly controlled by the steric hindrance, van der Walls, and electrostatic interactions between HA and Al 2 O 3 nanoparticles. Aggregation kinetics and attachment efficiency studies induced by the addition of Na + and Ca 2+ cations confirmed that divalent electrolytes could reduce the large energy barrier between the charged colloidal particles more efficiently, and induce a more aggressive aggregation of the particles. Additionally, the bridging effect of HA with Ca 2+ was also an important mechanism for the aggregation enhancement, which had been confirmed by the fluorescence excitation-emission matrix (EEM) spectra analysis. These findings are useful in understanding the environmental challenges of inorganic colloidal particles in natural environments.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2023
·
IF 8.2
Yajun Hou,Shanshan Wang,Baojuan Deng,Yun Ma,Xing Long,Chengrong Qin,Chen Liang,Caoxing Huang,Shuangquan Yao
As an environmentally friendly lignocellulosic biomass separation technology, hydrothermal pretreatment (HP) has a strong application prospect. However, the low separation efficiency is a main factor limiting its application. In this study, the poplar components were separated using HP with ferric chloride and pH buffer (HFB). The optimal conditions were ferric chloride concentration of 0.10 M, reaction temperature of 150 °C, reaction time of 15 min and pH 1.9. The separation of hemicellulose was increased 34.03 % to 77.02 %. The pH buffering resulted in the highest cellulose and lignin retention yields compared to ferric chloride pretreatment (FC). The high efficiency separation of hemicellulose via HFB pretreatment inhibited the degradation of xylose . The hydrolysate was effectively reused for five times. The fiber crystallinity index reached 60.05 %, and the highest C/O ratio was obtained. The results provide theoretical support for improving the efficiency of HP and promoting its application.
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Environmental Science-Nano
·
2023
·Vol. 10
·期 9
·2500-2513
·
IF 7.3
Chao Xue,Xiaoyun Yi,Yuebei Yang,Feng Jiang,Hua Yin,Zhi Dang
It has been widely believed that the adsorption mechanism of cadmium on iron (oxyhydr)oxide is solely the inner-sphere complexation based on extended X-ray absorption fine structure spectroscopy (EXAFS). However, these results were obtained at specific experiment settings (high ionic strength and high cadmium surface loading). In natural cadmium-polluted soil and water environments, such as acidic mineral drainage (AMD) areas, the pH/ionic strength is relatively low. Therefore, under practical conditions, the bonding pathway of cadmium could be different and may comprise other potential mechanisms. This work focuses on the proportion of different cadmium sorption pathways on goethite by employing a chemical extraction procedure. Cadmium is mostly adsorbed on goethite via electrostatic adsorption and inner-sphere complexation in a pH range of 5.5–7.5 under 10 mM ionic strength conditions. Through quantitative calculation, it is confirmed that the amount of Mg(NO3)2-extracted cadmium can refer to the content of electrostatically adsorbed cadmium. Two types of surface hydroxyls contributed differently to inner-sphere complexed Cd(II) at different pH values, and the emergence of surface-induced precipitates at higher pH could also be included in the retention mechanism. The behavior of electrostatically adsorbed cadmium and inner-sphere complexed Cd(II) was found to be different at different pH values when sulfate was introduced. Based on zeta potential and total reflectance Fourier transform infrared spectral analyses, sulfate would modify the surface charge of goethite, but, moreover, sulfate might form pseudo ion-group species with cadmium, which could influence the sorption pathway of cadmium.
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Journal of Materials Chemistry C
·
2023
·Vol. 11
·期 23
·7722-7731
·
IF 6.4
Xin Chen,Jianlong Ji,Yubo Peng,Zhipeng Gao,Min Zhao,Bin Tang,Ying Liu
With the advantages of miniaturization, simple device structure, and fast response, organic electrochemical transistors (OECTs) have become an emerging platform for developing wearable pH sensors for real-time human health monitoring. However, the application of devices is limited because they use water electrolytes. This paper proposed a feasible pH-sensitive OECT with a flexible BTB dye-embedded ion-gel dielectric layer. The real-time H+ detection performances of the devices, the effects of the BTB content in the ion-gel layer and gate voltages on the pH sensing capability, as well as the property–microstructure relationship of the ion-gel were investigated. The experimental results showed that the pH-sensitive OECT integrated with a 15 wt% BTB ion-gel layer exhibited outstanding H+ ion sensitivity and linear response properties at a gate voltage of −0.4 V. The pH-sensitive ion-gel modified OECT presented here provides a novel strategy for developing wearable pH sensors with high real-time monitoring characteristics.
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