Antibacterial Mechanism of d-Cysteine/Polyethylene Glycol-Functionalized Gold Nanoparticles and Their Potential for the Treatment of Bacterial Infections.

Bacterial infection has always posed a severe threat to public health. Gold nanoparticles (Au NPs) exhibit exceptional biocompatibility and hold immense potential in biomedical applications. However, their antibacterial effectiveness is currently unsatisfactory. Herein, a chiral antibacterial agent with high stability was prepared by the modification of Au NPs with d-cysteine with the assistance of polyethylene glycol (PEG). The as-synthesized d-cysteine/PEG-Au NPs (D/P-Au NPs) exhibited a stronger (99.5-99.9%) and more stable (at least 14 days) antibacterial performance against Gram-negative (Escherichia coli and Listeria monocytogenes) and Gram-positive (Salmonella enteritidis and Staphylococcus aureus) bacteria, compared with other groups. The analysis of the antibacterial mechanism revealed that the D/P-Au NPs mainly affected the assembly of ribosomes, the biosynthesis of amino acids and proteins, as well as the DNA replication and mismatch repair, ultimately leading to bacterial death, which is significantly different from the mechanism of reactive oxygen species-activated metallic antibacterial NPs. In particular, the D/P-Au NPs were shown to effectively accelerate the healing of S. aureus-infected wounds in mice to a rate comparable to or slightly higher than that of vancomycin. This work provides a novel approach to effectively design chiral antibacterial agents for bacterial infection treatment.

Stacking and ridge regression-based spectral ensemble preprocessing method and its application in near-infrared spectral analysis.

Spectral preprocessing techniques can, to a certain extent, eliminate irrelevant information, such as current noise and stray light from spectral data, thereby enhancing the performance of prediction models. However, current preprocessing techniques mostly attempt to find the best single preprocessing method or their combination, overlooking the complementary information among different preprocessing methods. These preprocessing techniques fail to maximize the utilization of useful information in spectral data and restrict the performance of prediction models. This study proposed a spectral ensemble preprocessing method based on the rapidly developing ensemble learning methods in recent years and the ridge regression (RR) model, named stacking preprocessing ridge regression (SPRR), to address the aforementioned issues. Different from conventional ensemble learning methods, the proposed SPRR method applied multiple different preprocessing techniques to the original spectral data, generating multiple preprocessed datasets. These datasets were then individually inputted into RR base models for training. Ultimately, RR still served as the meta-model, integrating the output results of each RR base model through stacking. This approach not only produced diversity in base models but also achieved higher accuracy and lower computational complexity by using a single type of base model. On the apple spectral dataset collected by our team, correlation analysis showed significant complementary information among the data produced by different preprocessing techniques. This provided robust theoretical support for the proposed SPRR method. By introducing the currently popular averaging ensemble preprocessing method in a comparative experiment, the results of applying the proposed SPRR method to six datasets (apple, meat, wheat, olive oil, tablet, and corn) demonstrated that compared to the single preprocessing method and averaging ensemble preprocessing method, SPRR yielded the best accuracy and reliability for all six datasets. Furthermore, under the same conditions of the training and test datasets, the proposed SPRR method demonstrated better performance than the four commonly used ensemble preprocessing methods.

Effects of bacterial cellulose/thyme essential oil emulsion coating on the shelf life of chilled chicken meat.

BACKGROUND: Bacterial cellulose (BC) is a fiber substance produced by microbial fermentation. It is widely used in the food preservation industry because of its extremely pure texture, high crystallinity and high biocompatibility. In the present study, bacterial cellulose/thyme essential oil (BC/TEO-E) with antibacterial and fresh-keeping functions was prepared by ultrasonic treatment of modified bacterial cellulose for encapsulation of thyme essential oil, which effectively inhibited the spoilage of chilled chicken. RESULTS: The purified BC, produced by Acetobacter xylinum ATCC 53524, was ultrasonically treated wih different times (0, 30, 60 and 90 min). Transmission electron microscopy, scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and zeta potential were used to characterize the structure of BC after ultrasound, showing that BC, treated for 30 min, had the optimal fiber structure, crystallinity (85.8%), thermal stability (347.77 °C) and solution stability (-26.63 ± 1.96 mV). BC/TEO-E was prepared by a homogenizer for the preservation of chilled chicken. Optical microscopy indicated that the BC/TEO-E prepared by 0.5% BC had optimal dispersion and stability, and even no delamination was observed in the emulsion. Compared with other groups (control, 0.5% BC and Tween-E), the total number of colonies and coliforms in chilled chicken treated with 0.5% BC/TEO-E was the lowest during the whole storage period (12 days), indicating that it can effectively inhibit bacterial growth. In addition, total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances, pH and drip loss results showed that 0.5% BC/TEO-E could effectively inhibit the spoilage of chilled chicken compared to the other treatment groups. CONCLUSION: All of the results acquired in the present study indicate that BC/TEO-E has a potential application in chilled chicken preservation. © 2024 Society of Chemical Industry.

Starch-based carbon aerogels prepared by an innovative KOH activation method for supercapacitors.

Biomass-based carbon aerogels hold promising application prospect in the field of supercapacitors. In this research, starch was selected as a raw material for preparing carbon aerogels. The preparation process of starch hydrogels was simplified by using KOH, which can change starch suspension into hydrogels at room temperature. Moreover, the molecular mixing of KOH and starch was realized, so that KOH can be fully utilized in the activation process. The specific surface area of the starch-based carbon aerogels prepared by this method was 1349 m2/g, and the proportion of micropores was 43.7 %. Remarkably, as electrode materials for supercapacitors, the starch-based carbon aerogels exhibited outstanding electrochemical performance. In a three-electrode system, the carbon aerogels exhibited specific capacitance of 211.5 F/g at 0.5 A/g and 138.5 F/g at 10 A/g, suggesting their suitability for high-current applications. In a symmetrical supercapacitor configuration, the materials exhibited an energy density of 11.3 Wh/kg at a power density of 0.5 kW/kg and the specific capacitance can maintain 98.91 % after 10,000 cycles. Overall, this work provides a new method for mixing activators, which will foster potential advances in starch based carbon aerogels.

Enhanced Inhibition of Drug-Resistant Escherichia coli by Tetracycline Hydrochloride-Loaded Multipore Mesoporous Silica Nanoparticles.

Drug-resistant bacterial infections exhibit a major threat to public health. Thus, exploring a novel antibacterial with efficient inhibition is urgently needed. Herein, this paper describes three types of MSNs (MSNs-FC2-R1, MSNs-FC2-R0.75, MSNs-FC2-R0.5) with controllable pore size (4-6 nm) and particle size (30-90 nm) that were successfully prepared. The MSNs were loaded with tetracycline hydrochloride (TCH) for effective inhibition of Escherichia coli (ATCC25922) and TCH-resistant Escherichia coli (MQ776). Results showed that the loading capacity of TCH in three types of MSNs was as high as over 500 mg/g, and the cumulative release was less than 33% in 60 h. The inhibitory rate of MSNs-FC2-R0.5 loaded with TCH against E. coli and drug-resistant E. coli reached 99.9% and 92.9% at the concentration of MIC, respectively, compared with the other two types of MSNs or free TCH. Modified MSNs in our study showed a great application for long-term bacterial growth inhibition.

Plasmon-Enhanced Antibacterial Activity of Chiral Gold Nanoparticles and In Vivo Therapeutic Effect.

d-cysteine (d-cys) has been demonstrated to possess an extraordinary antibacterial activity because of its unique steric configuration. However, inefficient antibacterial properties seriously hinder its wide applications. Here, cysteine-functionalized gold nanoparticles (d-/l-Au NPs) were prepared by loading d-/l-cysteine on the surface of gold nanoparticles for the effective inhibition of Escherichia coli (E. coli) in vitro and in vivo, and the effects on the intestinal microflora in mice were explored during the treatment of E. coli infection in the gut. We found that the antibacterial activity of d-/l-Au NPs was more than 2-3 times higher than pure d-cysteine, l-cysteine and Au NPs. Compared with l-Au NPs, d-Au NPs showed the stronger antibacterial activity, which was related to its unique steric configuration. Chiral Au NPs showed stronger destructive effects on cell membrane compared to other groups, which further leads to the leakage of the cytoplasm and bacterial cell death. The in vivo antibacterial experiment illustrated that d-Au NPs displayed impressive antibacterial activity in the treatment of E. coli-infected mice comparable to kanamycin, whereas they could not affect the balance of intestinal microflora. This work is of great significance in the development of an effective chiral antibacterial agent.

Neuro-protective roles of long non-coding RNA MALAT1 in Alzheimer's disease with the involvement of the microRNA-30b/CNR1 network and the following PI3K/AKT activation.

Long non-coding RNAs (lncRNAs) have been increasingly found to fulfill key functions in neurodegenerative diseases. This study aimed to probe the function of lncRNA MALAT1 in neuronal recovery in Alzheimer's disease (AD). Aß25-35 was used to induce AD in a rat model and neuronal injury in PC12 and C6 cells. Aberrantly expressed lncRNAs/microRNAs (miRNAs) in AD rats were screened out by microarray analyses. Altered expression of MALAT1, miR-30b and CNR1 was performed to explore their roles in neuronal recovery in rat and cell models. Consequently, LncRNA MALAT1 and CNR1 were poorly expressed while miR-30b was highly expressed in Aß25-35-induced rat models and cells. Overexpression of MALAT1 or CNR1 reduced neuronal injury in rat hippocampus. It increased viability and decreased apoptosis in injured PC12 and C6 cells, and decreased the secretion of pro-inflammatory factor IL-6 and TNF-α but increased IL-10 production. However, overexpression of miR-30b reversed these trends. MALAT1 could served as a sponge for mR-30b to up-regulate CNR1 expression. The phosphorylation of PI3K and AKT was stimulated when MALAT1 or CNR1 was overexpressed. To sum up, we found MALAT1 could promote neuronal recovery following AD through the miR-30b/CNR1 network and the PI3K/AKT signaling activation.

Aldehyde dehydrogenase 2 rs671G>A polymorphism and ischemic stroke risk in Chinese population: a meta-analysis.

Introduction: Recently, molecular epidemiological studies have suggested that aldehyde dehydrogenase 2 (ALDH2) rs671 G>A polymorphism may be a risk factor for ischemic stroke (IS). However, the results reported have not been consistent. Methods: We conducted the meta-analysis to explore the precise association between ALDH2 rs671 G>A polymorphism and IS risk. Five online databases were searched and the relative studies were reviewed from inception to October 1, 2018. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated in each genetic model of the general and subgroup. Furthermore, the heterogeneity, accumulative analyses, sensitivity analyses and publication bias were calculated simultaneously. Results: Overall, nine case-control studies involving 6,129 subjects were included in this meta-analysis. All studies were focused on the Chinese population and some significant associations were found between ALDH2 rs671 G>A polymorphism and IS risk (A vs G: OR=1.29, 95% CI=1.01-1.65, P=0.04, I2=78.2%; AA vs GG: OR=1.86, 95% CI=1.27-2.21, P<0.01, I2=11.3%; AA vs GG + GA: OR=1.67, 95% CI=1.27-2.19, P<0.01, I2=0%). Some significant and similar results were also observed in the subgroup analysis. Conclusion: Our meta-analysis indicates that the ALDH2 rs671 G>A polymorphism may play an important role in the occurrence of IS by reducing the activity of ALDH2 and interfering with the metabolic processes involving acetaldehyde.

Manganese oxide doping carbon aerogels prepared with MnO2 coordinated by N, N - dimethylmethanamide for supercapacitors.

Carbon aerogels with excellent conductive characteristics and high specific capacitance have attracted more and more interests for next-generation energy storage applications. Three-dimensional interconnected Mn2O3/carbon aerogel supercapacitor electrodes are prepared by a novel doping method using MnO2 coordinated by N, N-dimethylmethanamide (DMF). The coordinative MnO2 (DMF/MnO2) plays a key role in the sol-gel process of resorcinol and formaldehyde. The doped carbon aerogels exhibits a high specific surface area of 859 m2 g-1 and a good pore-size distribution of 10-15 nm. All of the doped carbon aerogels exhibit higher specific capacitance than pure carbon aerogels, and the highest specific capacitance (170 F g-1), at current density of 1.0 A g-1, is obtained in Mn-CA-5% when 5 mol% DMF/MnO2 is added to the precursor solution. The specific capacitance is as high as 100 F g-1, at current density of 10.0 A g-1, and 97% of initial capacitance is retained over 1000 cycles at a current density of 5.0 A g-1. The doped carbon aerogels exhibits a high coulombic efficiency (up to 99.8%) and a good rate capability. The corresponding result is due to the novel doping method of DMF/MnO2 addition.

Facile Preparation of Rod-like MnO Nanomixtures via Hydrothermal Approach and Highly Efficient Removal of Methylene Blue for Wastewater Treatment.

In the present study, nanoscale rod-shaped manganese oxide (MnO) mixtures were successfully prepared from graphitic carbon nitride (C3N4) and potassium permanganate (KMnO4) through a hydrothermal method. The as-prepared MnO nanomixtures exhibited high activity in the adsorption and degradation of methylene blue (MB). The as-synthesized products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), surface area analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Furthermore, the effects of the dose of MnO nanomixtures, pH of the solution, initial concentration of MB, and the temperature of MB removal in dye adsorption and degradation experiments was investigated. The degradation mechanism of MB upon treatment with MnO nanomixtures and H2O2 was studied and discussed. The results showed that a maximum adsorption capacity of 154 mg g-1 was obtained for a 60 mg L-1 MB solution at pH 9.0 and 25 °C, and the highest MB degradation ratio reached 99.8% under the following optimum conditions: 50 mL of MB solution (20 mg L-1) at room temperature and pH ≈ 8.0 with 7 mg of C, N-doped MnO and 0.5 mL of H2O2.

A Comparison of Electrochemical Performance of Carbon Aerogels with Adsorption Metal Ions for Super Capacitors.

Environmental problems caused by metal ions have caused widespread concern in recent years. In this work, carbon aerogels (CAs) adsorbing different metal ions were prepared. The adsorption performance and kinetics of metal ions (Cu(II), Cr(VI), and Fe(III)) on carbon aerogels were systematically investigated. The results indicated that the maximum adsorption capacity of Cu(II) was 424 mg·g-1 in 600 mg·L-1 copper solution. Adsorption performances of Cu(II), Cr(VI), and Fe(III) on CAs well fitted with a pseudo-second-order kinetic model. The structures and morphologies of metal-containing samples were characterized by scanning electron micrographs (SEM), Energy Dispersive Spectrometer (EDS), transmission electron microscope (TEM), and X-ray diffraction (XRD). The results demonstrated that the texture and electrochemical performance of CAs adsorbing metal ions exhibited a clear change. The specific surface area of CAs for adsorbing copper ions was 450 m²·g-1 and they showed a small average pore diameter (7.16 nm). Furthermore, CAs adsorbing metals could be used for the super capacitor. The specific capacitance of CAs adsorbing copper ions could reach 255 F·g-1 at a current density of 1.0 A·g-1. The CA-Cu electrode materials exhibited excellent reversibility with a cycling efficiency of 97% after 5000 cycles.

Carbon aerogel-based supercapacitors modified by hummers oxidation method.

Carbon aerogels of an inter-connected three-dimensional (3D) structure are a potential carbon material for supercapacitors. We report a new oxidation modification method to prepare a series of modified carbon aerogels (OM-CA) by Hummers oxidation method. Oxidation-modified carbon aerogels (OM-CA) are obtained from carbon aerogel powders oxidized by Hummers method. Sulfuric acid stoichiometry is studied in order to investigate the effect of the surface oxygen group on surface area and electrochemical performance. Additionally, heteroatoms are doped into carbon aerogels in the oxidation process. The effect of heteroatom doping on electrochemical performance as a supercapacitor electrode material is investigated. When the amount of sulfuric acid is 40 wt%, the dopping manganese content is 0.9 mol%, the specific surface area of OM-CA is 450 m2/g, and its specific capacitance is 151 F g-1 at 0.5 A g-1, which is achieved by heteroatom doping and texture properties. In addition, OM-CA composite supercapacitors exhibit a stable cycle life at a current density of 0.5 A g-1 and retain 98.0% of initial capacitance over 500 cycles, and OM-CA-40% still presents a higher capacity, up to 148 F g-1 at 0.5 A g-1. The high specific surface area and specific capacitance suggest the porous carbon material has potential applications in supercapacitors.

Significant association of BDNF rs6265 G>A polymorphism with susceptibility to epilepsy: a meta-analysis.

INTRODUCTION: Previously published articles have suggested that BDNF rs6265 G>A polymorphism is a potential risk factor for epilepsy. However, the results were not consistent. METHODS: We conducted a meta-analysis to explore the association between BDNF rs6265 G>A polymorphism and epilepsy risk. Four online databases were searched, and related studies were reviewed from their inception up to June 20, 2017. ORs and corresponding 95% CIs were used to calculate the associations of each genetic model. Overall, 10 case-control publications involving 9,512 subjects were included in this meta-analysis. RESULTS: Significant associations were found between BDNF rs6265 G>A polymorphism and epilepsy (A vs G: OR=0.88, 95% CI=0.83-0.94, P<0.01, I2=0%; GA vs GG: OR=0.88, 95% CI=0.79-0.97, P=0.01, I2=0%; AA vs GG: OR=0.79, 95% CI=0.70-0.90, P<0.01, I2=0%; GA+AA vs GG: OR=0.85, 95% CI=0.77-0.94, P<0.01, I2=0%; AA vs GG+GA: OR=0.85, 95% CI=0.76-0.95, P=0.01, I2=0%). Subgroup analysis also showed similar results in an Asian population. CONCLUSION: Our meta-analysis indicated that BDNF rs6265 G>A polymorphism might be involved in epilepsy susceptibility, especially in the Asian population.

miR-34a deficiency in APP/PS1 mice promotes cognitive function by increasing synaptic plasticity via AMPA and NMDA receptors.

MicroRNA (miR)-34a was recently determined to contribute to the pathological development of Alzheimer's disease (AD). miR-34a deficiency significantly attenuates cognitive deficits in amyloid precursor protein (APP)/presenilin 1 (PS1) mice; however, its role in early AD pathology and the underlying mechanisms remain elusive. Here, we confirmed that the increase of miR-34a expression in APP/PS1 mice was earlier than the relevant AD pathological characteristics, such as amyloid-ß production, amyloid plaque deposition, and cognitive deficits. Furthermore, because predicted miR-34a target genes were broadly linked to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartate (NMDA) receptors, we evaluated synaptic plasticity by investigating high-frequency conditioning tetanus-induced excitatory postsynaptic potential, which revealed that synaptic plasticity was promoted in miR-34a knockout/APP/PS1 mice. Therefore, we assessed the expression of the presynaptic components synaptophysin and postsynaptic density protein 95 (PSD95) and found that synaptophysin and PSD95 were not altered by miR-34a deficiency. Additionally, the synaptic strength (vesicular fusion, vesicular docking, and transporting) was either not significantly changed. We also evaluated the levels of AMPA and NMDA receptors, which showed that the expression of AMPA and NMDA receptors was markedly upregulated in APP/PS1 mice with miR-34a deficiency. We conclude that miR-34a is involved in synaptic deficits in AD pathological development, which was, at least in part, due to the inhibition of NMDA (by miR-34a-5p) and AMPA (by miR-34a-3p) receptor expression.

Silencing of Long Non-Coding RNA MALAT1 Promotes Apoptosis of Glioma Cells.

The metastasis-associated lung adenocarcinoma transcription 1 (MALAT1) is a highly conserved long non-coding RNA (lncRNA) gene. However, little is known about the pathological role of lncRNA MALAT1 in glioma. In the present study, we explored the expression level of lncRNA MALAT1 in primary glioma tissues as well as in U87 and U251 glioma cell lines. Using qRT-PCR, we found that the expression of lncRNA MALAT1 was significantly increased in glioma tissues compared with that of paracancerous tissues. Meanwhile, the expression of MALAT1 was highly expressed in U98 and U251 cells. In order to explore the function of MALAT1, the expression of MALAT1 was greatly reduced in U87 and U251 cells transfected with siRNA specifically targeting MALAT1. Consequently, cell viability of U87 and U251 cells were drastically decreased after the knockdown of MALAT1. Concomitantly, the apoptosis rate of the two cell lines was dramatically increased. Furthermore, the expression levels of some tumor markers were reduced after the knockdown of MALAT1, such as CCND1 and MYC. In summary, the current study indicated a promoting role of MALAT1 in the development of glioma cell.

Determination of alkaline phosphatase based on affinity adsorption solid-substrate room temperature phosphorimetry using rhodamine 6G-dibromoluciferin luminescent nanoparticle to label lectin and prediction of diseases.

In the presence of heavy atom perturber LiAc, the silicon dioxide nanoparticle containing rhodamine 6G (R) and dibromoluciferin (D) (R-D-SiO(2)) can emit strong and stable solid-substrate room temperature phosphorescence signal of R (lambda(ex)/lambda(em)=481/648 nm) and D (lambda(ex)/lambda(em)=457/622 nm) on the surface of acetyl cellulose membrane (ACM). R-D-SiO(2) is used to label triticum vulgare lectin (WGA). Then two types of affinity adsorption reactions, R-D-SiO(2)-WGA- alkaline phosphatase (ALP) (direct method) and WGA-ALP-WGA-R-D-SiO(2) (sandwich method), are carried out on ACM. The conditions and the analytical characteristics for the determination of ALP using affinity adsorption solid-substrate room temperature phosphorimetry (AA-SS-RTP) were studied. For a 0.40-microl drop of sample, results show that the detection limits of the sandwich method are 0.16 ag spot(-1)(457/622 nm) and 0.17 ag spot(-1)(481/648 nm), and the detection limits of the direct method are 0.41 ag spot(-1) (457/622 nm) and 0.44 ag spot(-1) (481/648 nm). The contents of ALP in human serum correlated well with those obtained by enzyme-linked immunoassay. This study shows that AA-SS-RTP whether by the sandwich method or the direct method, can combine very well the characteristics of both high sensitivity of SS-RTP and specificity of the immunoreaction. Simultaneously, whether the phosphorescence excitation/emission wavelength of either R or D in R-D-SiO(2) is chosen to determine ALP, this can promote the agility and widen the adaptability of AA-SS-RTP.