Boosted C-C coupling with Cu-Ag alloy sub-nanoclusters for CO2-to-C2H4 photosynthesis.

The selective photocatalytic conversion of CO2 and H2O to high value-added C2H4 remains a great challenge, mainly attributed to the difficulties in C-C coupling of reaction intermediates and desorption of C2H4* intermediates from the catalyst surface. These two key issues can be simultaneously overcome by alloying Ag with Cu which gives enhanced activity to both reactions. Herein, we developed a facile stepwise photodeposition strategy to load Cu-Ag alloy sub-nanoclusters (ASNCs) on TiO2 for CO2 photoreduction to produce C2H4. The optimized catalyst exhibits a record-high C2H4 formation rate (1110.6 ± 82.5 µmol g-1 h-1) with selectivity of 49.1 ± 1.9%, which is an order-of-magnitude enhancement relative to current work for C2H4 photosynthesis. The in situ FT-IR spectra combined with DFT calculations reveal the synergistic effect of Cu and Ag in Cu-Ag ASNCs, which enable an excellent C-C coupling capability like Ag and promoted C2H4* desorption property like Cu, thus advancing the selective and efficient production of C2H4. The present work provides a deeper understanding on cluster chemistry and C-C coupling mechanism for CO2 reduction on ASNCs and develops a feasible strategy for photoreduction CO2 to C2 fuels or industrial feedstocks.

Surface chemistry engineered selenium nanoparticles as bactericidal and immuno-modulating dual-functional agents for combating methicillin-resistant Staphylococcus aureus Infection.

Because of the extremely complexed microenvironment of drug-resistant bacterial infection, nanomaterials with both bactericidal and immuno-modulating activities are undoubtedly the ideal modality for overcoming drug resistance. Herein, we precisely engineered the surface chemistry of selenium nanoparticles (SeNPs) using neutral (polyvinylpyrrolidone-PVP), anionic (letinan-LET) and cationic (chitosan-CS) surfactants. It was found that surface chemistry greatly influenced the bioactivities of functionalized SeNPs, their interactions with methicillin-resistant Staphylococcus aureus (MRSA), immune cells and metabolisms. LET-functionalized SeNPs with distinct metabolisms exhibited the best inhibitory efficacy compared to other kinds of SeNPs against MRSA through inducing robust ROS generation and damaging bacterial cell wall. Meanwhile, only LET-SeNPs could effectively activate natural kill (NK) cells, and enhance the phagocytic capability of macrophages and its killing activity against bacteria. Furthermore, in vivo studies suggested that LET-SeNPs treatment highly effectively combated MRSA infection and promoted wound healing by triggering much more mouse NK cells, CD8+ and CD4+ T lymphocytes infiltrating into the infected area at the early stage to efficiently eliminate MRSA in the mouse model. This study demonstrates that the novel functionalized SeNP with dual functions could serve as an effective antibacterial agent and could guide the development of next generation antibacterial agents.

Prediction of strong coupling in resonant perovskite metasurfaces by deep learning.

Resonant metasurfaces are often used to achieve strong coupling, and numerical simulations are the common method for designing and optimizing structural parameters of metasurfaces, while their calculation process takes a lot of time and occupies more computing resources. In this work, the deep learning strategy is proposed to simulate the strong coupling phenomenon in resonant perovskite metasurfaces. The designed fully connected neural network is constructed based on the deep learning algorithm that is used to predict transmission spectra, multipole decomposition spectral lines, and anti-cross phenomena of a perovskite metasurface. Through comparison of numerical simulation results, it can be seen that the neural network can efficiently and accurately predict the strong coupling phenomenon. Compared with the traditional design process, the proposed deep learning model can guide the design of the resonant metasurface more quickly, which significantly improves the feasibility of the design in complex metasurface structures.

Tandem Acidic CO2 Electrolysis Coupled with Syngas Fermentation: A Two-Stage Process for Producing Medium-Chain Fatty Acids.

The tandem application of CO2 electrolysis with syngas fermentation holds promise for achieving heightened production rates and improved product quality. However, the significant impact of syngas composition on mixed culture-based microbial chain elongation remains unclear. Additionally, effective methods for generating syngas with an adjustable composition from acidic CO2 electrolysis are currently lacking. This study successfully demonstrated the production of medium-chain fatty acids from CO2 through tandem acidic electrolysis with syngas fermentation. CO could serve as the sole energy source or as the electron donor (when cofed with acetate) for caproate generation. Furthermore, the results of gas diffusion electrode structure engineering highlighted that the use of carbon black, either alone or in combination with graphite, enabled consistent syngas generation with an adjustable composition from acidic CO2 electrolysis (pH 1). The carbon black layer significantly improved the CO selectivity, increasing from 0% to 43.5% (0.05 M K+) and further to 92.4% (0.5 M K+). This enhancement in performance was attributed to the promotion of K+ accumulation, stabilizing catalytically active sites, rather than creating a localized alkaline environment for CO2-to-CO conversion. This research contributes to the advancement of hybrid technology for sustainable CO2 reduction and chemical production.

Association of preoperative frailty with the risk of postoperative delirium in older patients undergoing hip fracture surgery: a prospective cohort study.

OBJECTIVE: This study aimed to explore the correlation between preoperative frailty and the risk of postoperative delirium (POD) in older patients undergoing hip fracture surgery. METHODS: In total, 148 patients with hip fractures who were admitted to Tsinghua Changgung Hospital (Beijing, China) between January 2022 and January 2023 were involved in this study. Preoperative frailty scales were assessed, of which the CAM scale was postoperatively administered every morning and evening on days 1, 2, 3, 5, and 7. Binary logistic regression analysis was conducted to determine the correlation between preoperative frailty and the risk of POD. RESULTS: Among 148 older patients with hip fractures, 71 (48.0%) were identified as preoperative frail and 77 (52.0%) as non-frail. The overall incidence of POD on day 7 was 24.3% (36/148), and preoperative frailty was associated with a significantly higher risk of POD compared with non-frailty (42.3% vs. 7.8%, P < 0.001). The binary logistic regression analysis revealed that preoperative frailty was noted as an independent risk factor for the risk of POD in older patients undergoing hip fracture surgery (P = 0.002). CONCLUSION: Preoperative frailty increased the risk of POD in older patients undergoing hip fracture surgery. DISCUSSION: Preoperative assessment of frailty in geriatric hip surgery can timely identify potential risks and provide interventions targeting frailty factors to reduce the incidence of POD in older patients undergoing hip fracture surgery. The findings suggested that preoperative frailty could increase the risk of POD in older patients undergoing hip fracture surgery. Further research is necessary to determine whether perioperative interventions aimed at enhancing frailty can mitigate the risk of POD and improve prognosis in older patients undergoing hip fracture surgery.

The male reproductive toxicity after 5-Fluorouracil exposure: DNA damage, oxidative stress, and mitochondrial dysfunction in vitro and in vivo.

5-Fluorouracil (5-FU), a chemotherapeutic drug used to treat a variety of cancers, can enter the environment through different routes, causing serious public health and environmental concerns. It has been reported that 5-FU exposure adversely affects male reproductive function, and its effects on this system cannot be avoided. In this study, using western blotting and quantitative polymerase chain reaction studies, we found that 5-FU promoted testicular injury by inducing oxidative stress, which was accompanied by the inhibition of nuclear factor erythroid 2-related factor 2/antioxidant response element signaling. Accumulation of reactive oxygen species (ROS) aggravated 5-FU-mediated mitochondrial dysfunction and apoptosis in murine cell lines and testes, indicating oxidative stress and mitochondrial-dependent apoptotic signaling play crucial roles in the damage of spermatogenic cells caused. N-Acetyl-L-cysteine, an antioxidant that scavenges intracellular ROS, protected spermatogenic cells from 5-FU-induced oxidative damage and mitochondrial dysfunction, revealing the important role of ROS in testicular dysfunction caused by 5-FU. We found that 5-FU exposure induces testicular cell apoptosis through ROS-mediated mitochondria pathway in mice. In summary, our findings revealed the reproductive toxicological effect of 5-FU on mice and its mechanism, provided basic data reference for adverse ecological and human health outcomes associated with 5-FU contamination or poisoning.

Ectopic endometriotic stromal cells-derived lactate induces M2 macrophage polarization via Mettl3/Trib1/ERK/STAT3 signalling pathway in endometriosis.

Endometriosis is a gynaecological condition characterized by the growth of endometrium-like tissues within and outside of the pelvic cavity. Recent studies have demonstrated that aberrant infiltration of M2 macrophages is mainly responsible for the establishment of endometriotic lesions. A growing body of evidence shows that glycolysis and lactate accumulation have great impact on the regulation of immunomicroenvironment. However, the communication signal between glycolysis and macrophages is poorly defined in endometriosis. Hereby, we investigate the correlation between glycolysis and M2 macrophage infiltration in endometriosis. Next, we confirm that lactate is pivotal factor that drives macrophage M2-polarization to promote endometriotic stromal cells invasion in vitro and in vivo. In addition, we also identify that the activation of Mettl3 and its target gene Trib1 promote M2 macrophage polarization. Moreover, we also demonstrate that Trib1 induce M2 macrophage polarization via the activation of ERK/STAT3 signalling pathway. Finally, by injecting 2-DG into endometriosis mice model, we show that the restrain of glycolysis significantly reduces the progression of endometriosis, which provides evidence for lactate as a potential therapeutic strategy for the prevention and treatment of endometriosis.

Novel LINC01923 -anaplasticlymphoma kinase rearrangement identified in advanced lung adenocarcinoma with durable response to ensartinib: a case report.

Anaplastic lymphoma kinase ( ALK ) rearrangements are one of the most common mutations in nonsmall cell lung cancer. Majority of the ALK rearrangements were sensitive to crizotinib, yet some rare fusion types may less benefit. The patient with LINC01923-ALK fusion was treated with crizotinib for 1 week and developed an adverse rash reaction. Replaced with second-line treatment with esatinib, the patient had a partial response in the primary site and achieved a complete response in the brain metastases. The patient was treated successfully with ensartinib leading to a progression-free survival of 6 months (and counting). This is the first report on one lung adenocarcinoma patient with a novel LINC01923-ALK fusion beneficial from ensartinib, which provides more knowledge for ALK fusion spectrum.

Complete response to tislelizumab in a metastatic urothelial carcinoma after surgery associated with high tumor mutational burden: a case report.

Metastatic urothelial carcinoma (mUC) is associated with poor prognosis. Cisplatin-based combination chemotherapy is the preferred initial regimen for patients with mUC. However, a substantial proportion of patients cannot receive cisplatin-based chemotherapy due to renal impairment or other comorbidities. Currently, immune checkpoint inhibitors (ICI) showed to be effective in cisplatin-ineligible mUC patients on first-line treatment. Tislelizumab is an anti-human programmed death receptor-1 monoclonal IgG4 antibody, which was specifically engineered to minimize binding to FcɣR on macrophages to abrogate antibody-dependent phagocytosis. But there is no report of tislelizumab as a first-line treatment for cisplatin-ineligible patients with mUC currently. Here, we report a cisplatin-ineligible mUC patient with PD-L1-negative, microsatellite stable (MSS), high tumor mutational burden (TMB-H) obtained complete response receiving tislelizumab therapy after laparoscopic debulking surgery. Progression-free survival has exceeded 16 months since treatment with tislelizumab. To our knowledge, this is the first reported case of cisplatin-ineligible mUC patient with PD-L1-negative, MSS and TMB-H who responded well to tislelizumab as a first-line treatment. However, we still need more studies to assess the efficacy of tislelizumab as a first-line treatment in cisplatin-ineligible mUC patients and to confirm predictive values of TMB for efficacy of tislelizumab.

Center Volume and Survival Relationship for Neonates With Congenital Diaphragmatic Hernia Treated With Extracorporeal Life Support.

OBJECTIVES: Literature is emerging regarding the role of center volume as an independent variable contributing to improved outcomes. A higher volume of index procedures may be associated with decreased morbidity and mortality. This association has not been examined for the subgroup of infants with congenital diaphragmatic hernia (CDH) receiving extracorporeal life support (ECLS). Our study aims to examine the risk-adjusted association between center volume and outcomes in CDH-ECLS neonates, hypothesizing that higher center volume confers a survival advantage. DESIGN: Multicenter, retrospective comparative study using the Extracorporeal Life Support Organization database. SETTING: One hundred twenty international pediatric centers. PATIENTS: Neonates with CDH managed with ECLS from 2000 to 2019. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The cohort included 4,985 neonates with a mortality rate of 50.6%. For the 120 centers studied, mean center volume was 42.4 ± 34.6 CDH ECLS cases over the 20-year study period. In an adjusted model, higher ECLS volume was associated with lower odds of mortality: odds ratio (OR) 0.995 (95% CI, 0.992-0.999; p = 0.014). For an increase in one sd in volume, that is, 1.75 cases annually, the OR for mortality was lower by 16.7%. Volume was examined as a categorical exposure variable where low-volume centers (fewer than 2 cases/yr) were associated with 54% higher odds of mortality (OR, 1.54; 95% CI, 1.03-2.29) compared with high-volume centers. On-ECLS complications (mechanical, neurologic, cardiac, hematologic metabolic, and renal) were not associated with volume. The likelihood of infectious complications was higher for low- (OR, 1.90; 95% CI, 1.06-3.40) and medium-volume (OR, 1.87; 95% CI, 1.03-3.39) compared with high-volume centers. CONCLUSIONS: In this study, a survival advantage directly proportional to center volume was observed for CDH patients managed with ECLS. There was no significant difference in most complication rates. Future studies should aim to identify factors contributing to the higher mortality and morbidity observed at low-volume centers.

Differential effects of PEGylated Cd-free CuInS2/ZnS quantum dot (QDs) on substance P and LL-37 induced human mast cell activation.

CuInS2/ZnS-PEG quantum dots (QDs) are among the most widely used near infrared non-cadmium QDs and are favored because of their non-cadmium content and strong tissue penetration. However, with their increasing use, there is great concern about whether exposure to QDs is potentially risky to the environment and humans. Furthermore, toxicological data related to CuInS2/ZnS-PEG QDs are scarce. In the study, we found that CuInS2/ZnS-PEG QDs (0-100 µg/mL) could internalize into human LAD2 mast cells without affecting their survival rate, nor did it cause degranulation or release of IL-8 and TNF-α. However, CuInS2/ZnS-PEG QDs significantly inhibited Substance P (SP) and LL-37-induced degranulation and chemotaxis of LAD2 cells by inhibiting calcium mobilization. Lower concentrations of CuInS2/ZnS-PEG QDs promoted the release of TNF-α and IL-8 stimulated by SP, but higher concentrations of CuInS2/ZnS-PEG QDs significantly inhibited the release of TNF-α and IL-8. On the other hand, CuInS2/ZnS-PEG QDs promoted LL-37-mediated TNF-α release from LAD2 cells in a dose-dependent manner from 6.25 to 100 µg/mL, while release of IL-8 triggered by LL-37 was dose-dependently inhibited within a dose concentration of 12.5-100 µg/mL. Collectively, our data demonstrated that CuInS2/ZnS-PEG QDs differentially mediated human mast cell activation induced by SP and LL-37.

Tumor mutation burden as a biomarker in resected gastric cancer via its association with immune infiltration and hypoxia.

BACKGROUND: Tumor mutation burden (TMB) predicts immunotherapy efficacy in solid tumors. However, the biomarker role of TMB is still conflicting in resected tumors. We aimed to examine the association of TMB with prognosis and postoperative chemotherapy (CT) or radiochemotherapy (RCT) efficacy in resected gastric cancer (GC). METHODS: Whole-exome sequencing (WES) was performed in 73 resected GC specimens. Validation cohorts included 352 patients from The Cancer Genome Atlas (TCGA) and 222 patients from the Asian Cancer Research Group (ACRG). Immune infiltration and hypoxia were evaluated by transcriptome data and immunohistochemistry assay. RESULTS: TMB-high GC had favorable overall survival (OS) and disease-free survival (DFS), but the OS and DFS benefits with postoperative CT/RCT were more pronounced in TMB-low GC. These findings were consistent among all three cohorts and were maintained in the pooled cohort. Stratified by stages in the pooled cohort, stage III GC benefited from postoperative CT/RCT regardless of TMB level while stage Ib/II GC benefited from postoperative CT/RCT in TMB-low but not in TMB-high subgroup. TMB positively correlated with immune infiltration which was characterized by NK cell rather than CD8 + T cell enrichment. TMB-high GC was more hypoxic than TMB-low GC, and TMB-high stage Ib/II GC was the most hypoxic. CONCLUSIONS: High TMB may predict favorable prognosis in resected GC but poor response to postoperative CT/RCT in stage Ib/II subgroup, which may be determined by TMB-associated immune infiltration and hypoxia, respectively.

Efficient visible light photocatalytic NO abatement over SrSn(OH)6 nanowires loaded with Ag/Ag2O cocatalyst.

SrSn(OH)6 (SSOH) possesses a high oxidation potential in the valence band (VB), which is suitable for photocatalytic oxidation removal of pollutants. However, the electrons in the VB of these catalysts are difficult to transition to the conduction band (CB) under visible light, which makes it difficult to utilize sunlight effectively. In this work, Ag/Ag2O is loaded on the surface of SSOH nanowires, which stimulates the interfacial charge-transfer transition on SSOH. Compared with pure-phase SSOH, the NO abatement ratio of Ag/Ag2O-SSOH under visible light irradiation is increased to 45.10%. The e- in the VB of Ag2O are excited into the CB under visible light, and are further transferred to the Ag to react with O2 to produce superoxide radicals. The photo-excited e- in the VB of SSOH enter into the VB of Ag2O through interfacial charge-transfer transition to recombine with the photo-generated holes in the VB of Ag2O, thereby leaving photo-generated holes in the VB of SSOH. The holes in the VB of SSOH have sufficient oxidizing ability to oxidize the adsorbed hydroxyl groups into hydroxyl radicals. This work provides a new perspective for photocatalytic removal of pollutants by wide band gap photocatalyst under visible light.

Evaluation of the Relationship among Biogenic Amines, Nitrite and Microbial Diversity in Fermented Mustard.

Biogenic amines (BAs) and nitrites are both considered harmful compounds for customer health, and are closely correlated with the microorganisms in fermented mustard (FM). In this study, BAs and nitrite contents in fifteen FM samples from different brands were analyzed. The concentrations of cadaverine in one sample and of histamine in one sample were above the toxic level. Moreover, five FM samples contained a high level of nitrite, exceeding the maximum residue limit (20 mg/kg) suggested by the National Food Safety Standard. Then, this study investigated bacterial and fungal communities by high-throughput sequencing analysis. Firmicutes and Basidiomycota were identified as the major bacteria and fungi phylum, respectively. The correlations among microorganisms, BAs and nitrite were analyzed. Typtamine showed a positive correlation with Lactobacillus and Pseudomonas. Cadaverine and nitrite is positively correlated with Leuconostoc. Furthermore, thirteen strains were selected from the samples to evaluate the accumulation and degradation properties of their BAs and nitrite. The results indicated that the Lactobacillus isolates, including L. plantarum GZ-2 and L. brevis SC-2, can significantly reduce BAs and nitrite in FM model experiments. This study not only assessed the contents of BAs and nitrite in FM samples, but also provided potential starter cultures for BAs and nitrite control in the FM products industry.

Dynamic Transitions in Neuronal Network Firing Sustained by Abnormal Astrocyte Feedback.

Astrocytes play a crucial role in neuronal firing activity. Their abnormal state may lead to the pathological transition of neuronal firing patterns and even induce seizures. However, there is still little evidence explaining how the astrocyte network modulates seizures caused by structural abnormalities, such as gliosis. To explore the role of gliosis of the astrocyte network in epileptic seizures, we first established a direct astrocyte feedback neuronal network model on the basis of the hippocampal CA3 neuron-astrocyte model to simulate the condition of gliosis when astrocyte processes swell and the feedback to neurons increases in an abnormal state. We analyzed the firing pattern transitions of the neuronal network when astrocyte feedback starts to change via increases in both astrocyte feedback intensity and the connection probability of astrocytes to neurons in the network. The results show that as the connection probability and astrocyte feedback intensity increase, neuronal firing transforms from a nonepileptic synchronous firing state to an asynchronous firing state, and when astrocyte feedback starts to become abnormal, seizure-like firing becomes more severe and synchronized; meanwhile, the synchronization area continues to expand and eventually transforms into long-term seizure-like synchronous firing. Therefore, our results prove that astrocyte feedback can regulate the firing of the neuronal network, and when the astrocyte network develops gliosis, there will be an increase in the induction rate of epileptic seizures.

In Vivo Two-Way Redox Cycling System for Independent Duplexed Electrochemical Signal Amplification.

An in vivo two-way redox cycling system based on whole-cell bidirectional electron transfer was developed and applied for independent duplexed electrochemical signal amplification. This duplexed signal amplification system was established by activating the bacterial "inwards" electron transfer at low electrode potential for oxidative cycling, while accomplishing the bacterial "outwards" electron transfer at high electrode potential for reductive cycling. Therefore, with this two-way bioredox cycling system, simultaneous and independent amplification of the electrochemical signals for oxidation and reduction was achieved. More impressively, by using this duplexed signal amplification system, ultrasensitive and simultaneous detection of two different warfare toxins of Pseudomonas aeruginosa was achieved (sensitivity was improved 302 and 579 times, respectively), which makes it possible for double-checking early diagnosis of the P. aeruginosa infections.

Do Ventriculoperitoneal Shunts Increase Complications After Laparoscopic Gastrostomy in Children?

BACKGROUND: In patients requiring gastrostomies, ventriculoperitoneal (VP) shunts are a frequently encountered comorbidity. The objective of this study is to evaluate the postoperative management of children with VP shunts that undergo laparoscopic gastrostomy placement and determine their incidence of complications. MATERIALS AND METHODS: Children 18 y old or younger who underwent laparoscopic gastrostomy placement at a freestanding academic children's hospital between January 2014 and October 2016 were reviewed. Data collected included demographics, management, and outcomes. Patients were compared based on their presence of a VP shunt before laparoscopic gastrostomy. Statistical analysis was performed using chi square, Fisher's exact, and Wilcoxon rank-sum tests. RESULTS: We reviewed the medical records of 270 children that underwent laparoscopic gastrostomy placement by 15 pediatric surgeons. Of these, 9% (25) had a previously placed VP shunt. In comparing patients with a VP shunt with those without a VP shunt, there was no significant difference in median age (4 versus 3 y, P = 0.92), gender (48% versus 51% males, P = 0.80), body mass index (15 versus 16, P = 0.69), preoperative diet (48% versus 47% nasogastric tube dependent, P = 0.60), or procedure time (43 versus 42 min, P = 0.37). The postoperative management of these children was similar: day of initiation of postoperative feeds (84% versus 73% on postoperative day #1, P = 0.70), method of initiation of feeds (60% versus 55% continuous, P = 0.25), and type of initial feeds (83% versus 71% Pedialyte, P = 0.24). Similarly, there was no difference in hospital length of stay, return to the emergency department, or postoperative complications within 90 d (P > 0.05). CONCLUSIONS: Children with ventriculoperitoneal shunts do not have a higher rate of immediate complications after laparoscopic gastrostomy placement and may be managed similar to other children in the postoperative period.

Management of Pediatric Adhesive Small Bowel Obstruction: Do Timing of Surgery and Age Matter?

BACKGROUND: Adhesive small bowel obstruction (ASBO) in children is generally managed with initial observation. However, no clear guidelines exist regarding indications to operate. Our purpose was to compare outcomes of ASBO management to determine whether timing of surgery and patient age should affect management. MATERIALS AND METHODS: A retrospective review of children admitted to a tertiary care children's hospital for ASBO between 2011 and 2015 was performed. Data included demographics, imaging, operative findings, and clinical management, which were analyzed using χ2 test, Fischer's exact test, t-test, analysis of variance, or logistic regression when appropriate. RESULTS: We identified 258 admissions for 202 patients. Urgent operation was performed in 12% and the rest had nonoperative management (NOM), which was successful in 54%. Patients younger than 1 y of age were more likely to require operation (odds ratio 3.71, 95% confidence interval [CI] 1.69-8.15; P < 0.01), and patients with prior ASBO were less likely to require operation (odds ratio 0.51, 95% CI 0.31-0.84; P < 0.01). At presentation, fever was most common in patients who had urgent operation (22.3% versus failure of NOM 7.6% versus successful NOM 6.6%; P = 0.02), but there were no differences in leukocytosis or abdominal pain. Excluding urgent operations, bowel resection was more common when operation was delayed more than 48 h (32.6% versus 15.3%; P = 0.04). CONCLUSIONS: In children with adhesive small bowel obstruction, NOM can be successful, but when failure is suspected, early operation before 48 h should be considered to avoid bowel loss, especially in children younger than 1 y of age.

A mediator-free whole-cell electrochemical biosensing system for sensitive assessment of heavy metal toxicity in water.

A bioelectrochemical sensing system (BES) based on electroactive bacteria (EAB) has been used as a new and promising tool for water toxicity assessment. However, most EAB can reduce heavy metals, which usually results in low toxicity response. Herein, a starvation pre-incubation strategy was developed which successfully avoided the metal reduction during the toxicity sensing period. By integrating this starvation pre-incubation procedure with the amperometric BES, a sensitive, robust and mediator-free biosensing method for heavy metal toxicity assessment was developed. Under the optimized conditions, the IC50 (half maximal inhibitory concentration) values for Cu2+, Ni2+, Cd2+, and Cr6+ obtained were 0.35, 3.49, 6.52, 2.48 mg L-1, respectively. The measurement with real water samples also suggested this method was reliable for practical application. This work demonstrates that it is feasible to use EAB for heavy metal toxicity assessment and provides a new tool for water toxicity warning.

Pollution characteristics of antibiotics and antibiotic resistance of coliform bacteria in the Yitong River, China.

In this study, the concentrations of nine typical antibiotics, including sulfadiazine (SD), sulfamerazine (SMR), sulfamethazine (SM2), sulfamethoxazole (SMZ), ofloxacin (OFX), ciprofloxacin (CIP), trimethoprim (TMP), oxytetracycline (OTC), and tetracycline hydrochloride (TC), were detected in the Yitong River by solid-phase extraction high-performance liquid chromatography. The concentrations of the antibiotics were analyzed. Additionally, an improved immobilized substrate enzyme substrate method (DST-enzyme substrate method) was developed and used to evaluate the antibiotic resistance of coliform bacteria to OFX, CIP, enrofloxacin (ENR), TC, sulfisoxazole (SOX), and TMP in the Yitong River. The results showed that the concentrations of the nine antibiotics ranged from nd (not detected) to 1.361 µg/L. The detection rate and concentration of OFX were the highest, followed by CIP, and the detection rate and concentration of SM2 and OTC were the lowest. The detection rate and concentrations of antibiotics were higher in August and November than those in May. The antibiotics were mainly distributed in the livestock sewage discharge and suburban domestic sewage discharge areas. Moreover, the drug resistance of total coliform bacteria to fluoroquinolones, sulfonamides, tetracyclines, and TMP varied with season.