Online electrochemistry coupling liquid chromatography-mass spectrometry for rapid investigation on the phase I and phase II simulated metabolic reactions of flavonoids.

In this study, an online electrochemistry coupling high-performance liquid chromatography-mass spectrometry (EC-HPLC-MS) technology has been developed for simulating metabolic reactions and rapid analysis of metabolites of flavone, quercetin, and rutin, which are not only widely present compounds with pharmacological activity in nature, but also have structural similarity and variability. The simulated metabolic processes of the substrates (phase I and phase II metabolism) were implemented on the surface of glassy carbon electrode (GCE) by using different electrochemical methods. After online chromatographic separation, the products were transmitted to a mass spectrometer for detection, in order to speculate relevant reaction pathways and structural information of the reaction product. The main metabolites, including methylation, hydroxylation, hydrolysis, and conjugation reaction products, had been successfully identified through the designed in situ hyphenated technique. Furthermore, compared with metabolites produced by in vitro incubation of rat liver microsomes, it was found that the products of electrochemical simulated metabolism were more abundant with diverse metabolic pathways. The results indicated that the proposed method exhibited advantages in the sample pretreatment process and detection cycle without compromising the reliability and accuracy of the results.

Effect of silver sulfadiazine on mature mixed bacterial biofilms on voice prostheses.

BACKGROUND: Biofilm formation on voice prostheses disrupts the function and limits the lifespan of voice prostheses. There is still no effective clinical strategy for inhibiting or removing these biofilms. Silver sulfadiazine (SSD), as an exogenous antibacterial agent, has been widely used in the prevention and treatment of infection, however, its effect on voice prosthesis biofilms is unknown. The purpose of this study was to explore the effect of SSD on the mature mixed bacterial biofilms present on voice prostheses. METHODS: Quantitative and qualitative methods, including the plate counting method, real-time fluorescence quantitative PCR, crystal violet staining, the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) (XTT) reduction assay, scanning electron microscopy, and laser confocal microscopy, were used to determine the effect of SSD on the number of bacterial colonies, biofilm formation ability, metabolic activity, and ultrastructure of biofilms in a mature mixed bacterial (Staphylococcus aureus, Streptococcus faecalis and Candida albicans) voice prosthesis biofilm model. The results were verified in vitro on mature mixed bacterial voice prosthesis biofilms from patients, and the possible mechanism of action was explored. RESULTS: Silver sulfadiazine decreased the number of bacterial colonies on mature mixed bacterial voice prosthesis biofilm, significantly inhibited the biofilm formation ability and metabolic activity of mature voice prosthesis biofilms, inhibited the formation of the complex spatial structure of voice prosthesis biofilms, and inhibited the synthesis of polysaccharides and proteins in the biofilm extracellular matrix. The degree of inhibition and removal effect increased with SSD concentration. CONCLUSIONS: Silver sulfadiazine can effectively inhibit and remove mature mixed bacterial voice prosthesis biofilms and decrease biofilm formation ability and metabolic activity; SSD may exert these effects by inhibiting the synthesis of polysaccharides and proteins among the extracellular polymeric substances of voice prosthesis biofilms.

[Efficacy of Activated Autologous Hematopoietic Stem Cell Transplantation in the Treatment of Acute Myeloid Leukemia].

OBJECTIVE: To compare the efficacy of activated autologous bone marrow and peripheral blood hematopoietic stem cell transplantation (Auto-HSCT) and matched sibling donor allogeneic hematopoietic stem cell transplantation (MSD-HSCT) for the first complete remission of adult acute myeloid leukemia (AML-CR1). METHODS: For 86 adult patients with first complete remission of AML who underwent auto-HSCT (41 cases) and MSD-HSCT (45 cases) in our hospital from June 2012 to June 2020, the patients were treated with modified MAC ï¼»Malflane 160 mg/(m2·d), -3 days, Ara-C 2 g/(m2·2), -3 days 21∶00, -2 days 9∶00, CTX 60 mg/(kg·d),-3 d, -2 dï¼½, the stem cells were activated by IL-2 (1 000 U/ mL), IFN-α (100 U/ mL) and IFN-γ (100 U/ml). The overall survival (OS), leukemia free survival (LFS), cumulative incidence of recurrence (CIR) and non-recurrence mortality (NRM) of patients with different types of transplantation were compared. RESULTS: The 3-year OS rates of Auto-HSCT group and MSD-HSCT group were 75% and 69.5%, and the 3-year LFS rates were 70.6% and 82.4%, respectively. There was no statisticaly significant difference in the 3-year OS rates of low risk, medium risk and high risk patients in the Auto-HSCT and MSD-HSCT group (90.2% vs 87.5%, 68.4% vs 68.8%, 28.6% vs 53.3%), the LFS rates of low risk, medium risk and high risk patients in the auto-HSCT and MSD-HSCT group were 90.2% and 87.5%(P=0.838), 71.8% and 91.7%(P=0.184), 0 and 67.5%(P=0.027), respectively. The NRM of Auto-HSCT and MSD-HSCT group were 4.9% and 20% (P=0.036), and CIR were 24.4% and 13.3% (P=0.188). Univariate analysis showed that the survival time of patients was significantly correlated with the number of CR courses and disease risk stratification (P=0.005, P=0.000). Cox multivariate analysis showed that disease risk stratification was an independent risk factor affecting OS (P=0.001). CONCLUSION: For adult patients with primary AML-CR1, Auto-HSCT is safe and effective. In the absence of sibling donor, Auto-HSCT can be regarded as an effective post-remission treatment for patients with intermediate risk AML-CR1.

Efficacy and safety of microneedling, fractional CO2 laser, and cryotherapy combined with 5-aminolevulinic acid photodynamic therapy in the treatment of actinic keratosis: A multicenter prospective randomized controlled study.

BACKGROUND: Photodynamic therapy (PDT) for actinic keratosis (AK) is limited by the depth of treatment. Microneedling or fractional CO2 laser can facilitate the penetration of photosensitizer, while cryotherapy can treat deeper tissues but is not suitable for field cancerization. OBJECTIVE: To investigate the efficacy of microneedling, fractional CO2 laser, and cryotherapy in combination with PDT for AK. METHODS: Patients with AK were randomized into 4 groups, including group A with microneedling + PDT, group B with fractional CO2 laser + PDT, group C with cryotherapy + PDT, and group D with PDT. After 12 weeks, the clinical, dermoscopic, and reflectance confocal microscopy (RCM) outcomes were assessed. RESULTS: A total of 129 patients were included in this study, with 31, 30, 35, and 31 patients in each group, yielding clinical response rates of 90.3%, 93.3%, 97.1%, and 74.2%, respectively (P=0.026). The RCM response rates were 71.0%, 80.0%, 85.7%, and 54.8%, respectively (P=0.030). The dermoscopic response rates were 77.4%, 83.3%, 88.6%, and 60.0%, respectively (P=0.039). Group C showed the best efficacy in terms of clinical, dermoscopic, and RCM outcomes. CONCLUSIONS: All three treatments improved the efficacy of PDT and were well tolerated, with cryotherapy + PDT showing the best efficacy.

Spatial Allocation Method of Evacuation Guiders in Urban Open Public Spaces: A Case Study of Binjiang Green Space in Xuhui District, Shanghai, China.

Evacuation guiders play an important role when emergency events occur in urban open public spaces. Considering the shortcomings of the existing studies, an optimization method based on the Particle Swarm Optimization (PSO) algorithm and gradual covering model for spatial allocation of evacuation guiders in urban open public spaces is proposed. This method considers the impact of obstacles on intervisibility between guiders and evacuees, and the non-linear changing characteristics of the evacuation guiding quality based on the distances between guiders and evacuees to optimize the space allocation of evacuation guiders in urban open public spaces. Based on the emergency evacuation simulation, the evacuation efficiencies before and after the optimization of evacuation guider allocation can be compared to verify the validity of the proposed method. Furthermore, in order to improve the applicability of this method, the responsibility areas of the evacuation guiders are zoned according to different time periods. A case study of Binjiang Green Space in Xuhui District, Shanghai, China was conducted to demonstrate the feasibility of the proposed method. The results showed that the spatial allocation of evacuation guiders was highly correlated with the dynamic spatial change of evacuees. The reasonable spatial allocation optimization of evacuation guiders can effectively improve the emergency evacuation quality and reduce evacuation risks. The zoning of the evacuation guiders' responsibility areas can help to clarify the responsibility area of each guider and provide a daily safety precaution scheme under a limited number of guiders. The method can provide detailed decision support for the security precaution of security staff and emergency evacuation management in urban open public spaces.

In-situ growth of nitrogen-doped carbonized polymer dots on black phosphorus for electrochemical DNA biosensor of Escherichia coli O157: H7.

Sensitive and accurate detection technology for pathogenic bacteria is of great social and economic significance in foodborne disease and food safety. In this paper, a novel portable electrochemical DNA biosensor for the detection of specific DNA sequence of Escherichia coli (E. coli) O157: H7 was constructed. To enhance the performance of the electrochemical sensor, a functionalized nitrogen-doped carbonized polymer dots in-situ grown on few-layer black phosphorus (N-CPDs@FLBP) was synthesized and used as the modifier on the surface of screen-printed electrode. Combining gold nanoparticles as immobilization matrix and methylene blue as electrochemical indicator, the analytical performance of this electrochemical DNA biosensor was evaluated using standard complementary ssDNA sequence in the linear concentration range from 1.0 × 10-19 to 1.0 × 10-6 mol/L with a low detection limit as 3.33 × 10-20 mol/L (3 σ). Furthermore, the portable electrochemical DNA biosensor was proposed based on polymerase chain reaction amplification for the detection of the E. coli O157: H7 genomic DNA from chicken meat, which verified the feasibility for practical samples detection. The research has great theoretical and practical significance for the development of electrochemical biosensor of pathogenic bacteria.

Clinical study of injectable collagen scaffold with autologous fat cells for repair of severe vocal fold injury.

Cell retention and survival after transplantation remains a major problem for long-term efficiency in therapy of severe vocal fold injury with autologous cells. In this study, injectable collagen scaffold was used to deliver autologous fat cells (AFCs) for repairing of severe vocal fold injury. We found injectable collagen scaffold could enhance the retention and survival of green fluorescent protein (GFP) labeled fat cells in the transplantation sites in rats. Based on these data, a randomized controlled clinical trial was conducted to evaluate the safety and efficiency of transplantation of collagen scaffold with AFCs for severe vocal fold injury. Ten patients with vocal fold paralysis were randomly assigned to control (AFCs only) and intervention (AFCs + collagen) groups. AFCs with or without collagen scaffold were injected into vocal folds of patients under general anesthesia, respectively. The safety and efficacy were regularly assessed during 24 months post-surgery. No obvious complications occurred in all patients during the follow-up. The collagen scaffold maintained the stability of implants after injection and reconstructed the vocal fold structure. The improvement of voice quality of patients was observed through voice quality evaluation with the voice handicap index (VHI) questionnaire, as well as acoustic analysis of maximum phonation time, jitter, and shimmer. The VHI score of patients in AFCs + collagen group improved significantly than those in AFCs group at 6, 12 and 24 months post-surgery. It demonstrates the injectable collagen scaffold is safe and efficient for delivering AFCs for vocal fold injury.

COVID-19 pandemic: study on simple, easy, and practical relaxation techniques while wearing medical protective equipment.

BACKGROUND: No studies have reported on how to relieve distress or relax in medical health workers while wearing medical protective equipment in coronavirus disease 2019 (COVID-19) pandemic. The study aimed to establish which relaxation technique, among six, is the most feasible in first-line medical health workers wearing medical protective equipment. METHODS: This was a two-step study collecting data with online surveys. Step 1: 15 first-line medical health workers were trained to use six different relaxation techniques and reported the two most feasible techniques while wearing medical protective equipment. Step 2: the most two feasible relaxation techniques revealed by step 1 were quantitatively tested in a sample of 65 medical health workers in terms of efficacy, no space limitation, no time limitation, no body position requirement, no environment limitation to be done, easiness to learn, simplicity, convenience, practicality, and acceptance. RESULTS: Kegel exercise and autogenic relaxation were the most feasible techniques according to step 1. In step 2, Kegel exercise outperformed autogenic relaxation on all the 10 dimensions among the 65 participants while wearing medical protective equipment (efficacy: 24 v. 15, no space limitation: 30 v. 4, no time limitation: 31 v. 4, no body position requirement: 26 v. 4, no environment limitation: 30 v. 11, easiness to learn: 28 v. 5, simplicity: 29 v. 7, convenience: 29 v. 4, practicality: 30 v. 14, acceptance: 32 v. 6). CONCLUSION: Kegel exercise seems a promising self-relaxation technique for first-line medical health workers while wearing medical protective equipment among COVID-19 pandemic.

Inhibition and Removal of Mature Mixed-Bacteria Biofilms on Voice Prostheses by Sodium Selenite.

Purpose: Biofilms on voice prostheses are important factors shortening their service life. Sodium selenite has been used to prevent and treat various diseases. Whether sodium selenite can inhibit and remove mature biofilms on voice prostheses is still unknown. Methods: To verify the effects of sodium selenite on mature mixed-bacteria biofilms (Staphylococcus aureus, Candida albicans, and Streptococcus faecalis) on voice prostheses, we used quantitative and qualitative methods, eg, real-time fluorescence quantitative PCR, crystal violet staining, 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) (XTT) reduction assays, and scanning electron microscopy, to measure the effects of sodium selenite on the number of bacterial colonies, biofilm formation ability, metabolic activity, and ultrastructure in a model of mature mixed-bacteria biofilms on voice prostheses and validated the effects in vitro on mature biofilms on voice prostheses from patients. Results: When exploring the possible mechanism of biofilm inhibition and removal by sodium selenite, we found that it significantly inhibited and removed biofilms on voice prostheses and effectively destroyed the spatial structure of the biofilms. The inhibition and removal effects became more significant with increasing sodium selenite concentrations. Conclusion: We demonstrated that sodium selenite can inhibit and remove biofilms of mature mixed strains on voice prostheses, providing a novel basis for treating patients' voice prosthesis biofilms.

Non-classic splicing mutation in the CPLANE1 (C5orf42) gene cause Joubert syndrome in a fetus with severe craniocerebral dysplasia.

BACKGROUD: Joubert syndrome is a rare neurodevelopmental disorder characterized by clinical and genetic heterogeneity. The characteristic molar tooth sign, which resulted from cerebellar vermis hypoplasia and midbrain anomalies, is expected to be the key diagnostic feature for this disease. However, it is not easy to make a definite diagnosis in prenatal only based on the imageology due to its clinical heterogeneity. CASE REPORT: We report on a fetus who was detected cerebellum dysplasia and encephalocele by ultrasound at 19 and 23 gestational weeks and confirmed by MRI examination. The pregnancy was terminated at 23 weeks of gestation. Postaxial polydactyly and deficiency in occipital bone and skin were identified in the induced fetus. RESULTS: The whole exome sequencing identified a novel compound heterozygous variation in the CPLANE1 gene related with Joubert syndrome, including a 2-bp insertion, NM_023073.3:c.1383_1384dup; p.(Gly462Glufs*3) and a non-classic splicing variation, NC_000005.10(NM_023073.3):c.7691-5_7691-4del. The pathogenicity of the non-classic splicing variation was further confirmed by cDNA level sequencing, which showed a exon 39 skipping that would introduce a premature termination. The novel compound heterozygous variation caused a complete function loss of the CPLANE1 gene. CONCLUSION: The cerebellum dysplasia fetus without obvious molar tooth sign was finally diagnosed as Joubert syndrome, combined with genetic detecting and the postnatal clinical symptoms. We also highlight the clinical heterogeneity of encephalodysplasia in Joubert syndrome, which increases the clinical diagnosis difficulty, especially for prenatal diagnosis. Our findings provided a new perspective for the prenatal diagnosis of Joubert syndrome with severe craniocerebral dysplasia and expanded the variation spectrum of the CPLANE1 gene.

Analysis of reflux as the aetiology of laryngeal dysplasia progression through a matched case-control study.

OBJECTIVES: Laryngeal dysplasia (LD) is a precancerous lesion of the larynx. In this study, the laryngeal tissue of patients with laryngeal dysplasia was taken as the research object, and the aetiology of reflux was analysed. METHOD: Patients with laryngeal dysplasia after surgery were selected as our subjects. The levels of pepsin, enterokinase and bilirubin in laryngeal tissue samples of the two groups were detected by immunohistochemical method. RESULTS: The OR values (95% CI) of pepsin, enterokinase and bilirubin were 0.67 (0.19-2.36), 0.80 (0.22-2.98) and 1.33 (0.30-5.96), respectively, in the univariate analysis. Besides, in the multivariate analysis, the OR values (95% CI) of pepsin, enterokinase and bilirubin were 0.57 (0.14-2.30), 0.73 (0.18-2.92) and 1.40 (0.30-6.53), respectively. CONCLUSION: Larger sample size should be applied to prospective studies on whether reflux is a risk factor for laryngeal cancer.

Post-COVID-19 Epidemic: Allostatic Load among Medical and Nonmedical Workers in China.

BACKGROUND: As the fight against the COVID-19 epidemic continues, medical workers may have allostatic load. OBJECTIVE: During the reopening of society, medical and nonmedical workers were compared in terms of allostatic load. METHODS: An online study was performed; 3,590 Chinese subjects were analyzed. Socio-demographic variables, allostatic load, stress, abnormal illness behavior, global well-being, mental status, and social support were assessed. RESULTS: There was no difference in allostatic load in medical workers compared to nonmedical workers (15.8 vs. 17.8%; p = 0.22). Multivariate conditional logistic regression revealed that anxiety (OR = 1.24; 95% CI 1.18-1.31; p < 0.01), depression (OR = 1.23; 95% CI 1.17-1.29; p < 0.01), somatization (OR = 1.20; 95% CI 1.14-1.25; p < 0.01), hostility (OR = 1.24; 95% CI 1.18-1.30; p < 0.01), and abnormal illness behavior (OR = 1.49; 95% CI 1.34-1.66; p < 0.01) were positively associated with allostatic load, while objective support (OR = 0.84; 95% CI 0.78-0.89; p < 0.01), subjective support (OR = 0.84; 95% CI 0.80-0.88; p < 0.01), utilization of support (OR = 0.80; 95% CI 0.72-0.88; p < 0.01), social support (OR = 0.90; 95% CI 0.87-0.93; p < 0.01), and global well-being (OR = 0.30; 95% CI 0.22-0.41; p < 0.01) were negatively associated. CONCLUSIONS: In the post-COVID-19 epidemic time, medical and nonmedical workers had similar allostatic load. Psychological distress and abnormal illness behavior were risk factors for it, while social support could relieve it.

Effects of Antiacid Therapy on Granuloma after Transoral Type IV-VI Cordectomy in Patients with Early-Stage Glottic Cancer.

OBJECTIVE: To investigate whether preventive administration of a proton pump inhibitor (PPI) can reduce the occurrence and development of traumatic granuloma (TG) following type IV-VI cordectomy. METHODS: We retrospectively analyzed the status of postoperative granulomas in 37 patients who underwent type IV-VI cordectomy due to glottic cancer and determined whether postoperative administration of a PPI had any impact on granuloma formation and development. RESULTS: The percentage and number of patients with granuloma in the PPI treatment group (experimental group) at the 1st, 2nd, 3rd, and 6th month following surgery were 81.25% (13/16), 25.00% (4/16), 18.75% (3/16), and 0.00% (0/16), respectively. The percentage and number of patients with granuloma in the no-PPI group (control group) were 95.24% (20/21), 71.43% (15/21), 52.38% (11/21), and 14.29% (3/21), respectively. The granuloma percentage of the PPI treatment group was lower than that of the control group at all postoperative time points assessed. The differences were not statistically significant at the 1st month (p = 0.175) but were statistically significant at the 2nd and 3rd months after surgery (p = 0.005, p = 0.037). CONCLUSION: Preventive use of a PPI in patients after type IV-VI cordectomy can shorten the TG recovery duration and may reduce the severity of TG, but it cannot prevent TG from occurring. Our results should be confirmed by prospective randomized controlled trials with large sample sizes.

Fabrication of ZIF-67@three-dimensional reduced graphene oxide aerogel nanocomposites and their electrochemical applications for rutin detection.

Three-dimensional reduced graphene oxide aerogel (3D rGA) was synthesized by hydrothermal method and cobalt imidazolate framework-67 (ZIF-67) was further grown in situ on the 3D rGA matrix directly. The resultant ZIF-67@3D rGA nanocomposite was checked by different techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrophotometry (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA). The presence of 3D rGA acted as the backbone for the loading of ZIF-67, and the resultant ZIF-67@3D rGA nanocomposite exhibited an interconnected porous structure with large surface area and high conductivity due to synergistic effects, which was applied to the electrode modification and used for rutin detection. The developed method showed excellent performance with a wider linear range (0.05-200.0 µmol/L) and lower detection limit (0.028 ± 0.0016 µmol/L, S/N=3). Various samples including the compounded rutin tablets and onions were analyzed by this modified electrode with satisfactory results.

[Genotype and phenotype studies on fetuses of 22q11.2 deletion syndrome].

OBJECTIVE: To study the genotype and phenotype of fetuses with 22q11.2 microdeletion and other abnormalities such as cardiac malformation and cleft palate. METHODS: Fetal ultrasound was carried out at 12 weeks to 20 to 24 weeks of gestation. After excluding the chromosomal karyotype abnormality, single nucleotide polymorphism (SNP) array was used to detect copy number variations of 5 fetuses with heart development abnormality or other structural abnormalities. The fetus with 22q11.2 microdeletion and its parents were also subjected to multiplex ligation-dependent probe amplification (MLPA) assay. RESULTS: SNP array analysis showed that the 5 fetuses had all carried a 2.27-3.02 Mb deletion of the 22q11.2 region. MLPA assay confirmed that LCR22-A-B was involved in all cases, and that all deletions were de novo in origin. CONCLUSION: It is of great significance to exclude 22q11.2 microdeletions in fetuses with cardiac malformations. The deletion regions of these fetuses are similar but different, and the phenotypic difference is related to their genotypes.

Perchlorate bioreduction by anaerobic granular sludge immobilised with Fe-HA complex: Performance, extracellular polymeric substances and microbial community structure.

An iron-humic acid (Fe-HA) complex was used as a redox mediator in perchlorate (ClO4-) bioreduction. Bioreduction performance, extracellular polymeric substances (EPS), and microbial community structure were comprehensively explored using different types of anaerobic granular sludge (AnGS) immobilised without the Fe-HA complex (AnGSCON) and with the Fe-HA complex (AnGSFH). The ClO4- was completely removed by AnGSCON by day 20, while the ClO4- was completely removed by AnGSFH by day 6. The AnGS immobilised with the Fe-HA complex significantly increased the ClO4- bioreduction. The acceleration of ClO4- bioreduction was also explained by the mixed liquor volatile suspended solids (MLVSS), MLVSS/mixed liquor suspended solids (MLSS), EPS composition, and microbial community structure. Compared with AnGSCON, the MLVSS and MLVSS/MLSS of the AnGSFH increased 1.4- and 1.2-fold, respectively. Humic substances in the EPS were stimulated by the Fe-HA complex. The microbial community structure analysis indicated that perchlorate and quinone reducing bacteria were enriched by the Fe-HA complex. Based on the analysis, the ClO4- bioreduction mechanism of the AnGSFH was revealed because the Fe-HA complex in the AnGS increased the biomass concentration, biological activity, and redox-active mediator and shifted the microbial community structure.

ZnO-reduced graphene oxide composite based photoelectrochemical aptasensor for sensitive Cd(II) detection with methylene blue as sensitizer.

In this paper a photoelectrochemical (PEC) aptasensor based on specific recognition with conformational changed after the target Cd(II) identification was fabricated. A ZnO and reduced graphene oxide (ZnO-rGO) nanocomposite with enhanced PEC activity was designed as photoactive material. After the further incorporation of gold nanoparticles (AuNPs) with ZnO-rGO nanocomposite, the enhanced photocurrent signal could be detected owing to the localized surface plasmon resonance and good conductivity of AuNPs. In addition, AuNPs were used as anchors for immobilization of -SH modified aptamer S1. After that aptamer S2 was paired with S1 sequence to form complementary double stranded DNA (dsDNA) on the electrode surface. Methylene blue (MB) was acted as sensitizer and assembled in dsDNA structure to amplify photocurrent response. When Cd(II) was bound to the aptamer presented on the sensing interface, S2 specifically recognized and captured Cd(II), which resulted in the unwinding of dsDNA structure and the separation of MB molecules from the electrode surface with photocurrent response decreased. The photocurrent was detected by a double-working-electrode system, which used the modified electrode as the first working electrode and glassy carbon electrode (GCE) as the second working electrode. Dopamine (DA) was added to the electrolyte and acted as the electron donor, which could be oxidized on the modified electrode and reduced on the GCE to form a cyclic reaction, leading to the enhanced photocurrent response with improved photocurrent stability. This MB sensitized PEC aptasensor exhibited a high sensitivity with a detection limit of 1.8 × 10-12 mol/L (3σ). Thus, a highly sensitive aptasensor with double-working-electrode detection method for Cd(II) determination were established and further applied to the water samples analysis.

Synthesis and utilization of Co3O4 doped carbon nanofiber for fabrication of hemoglobin-based electrochemical sensor.

In this paper cobalt oxide (Co3O4) nanoparticles were mixed with polyacrylonitrile to prepare Co3O4 doped carbon nanofiber (CNF) composite by electrospinning and carbonization, which was further used to modify on carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on Co3O4-CNF/CILE surface with Nafion acted as the protective film to fabricate an electrochemical biosensor (Nafion/Hb/Co3O4-CNF/CILE). Electrochemical behavior of Hb on the electrode was investigated with a pair of quasi-reversible redox peak appeared on cyclic voltammogram and electrochemical parameters were calculated. Moreover, this biosensor had good analytical capabilities for electrocatalytic reduction of different substrates including trichloroacetic acid, potassium bromate and sodium nitrite with wider detection range from 40.0 to 260.0 mmol L-1, 0.1 to 48.0 mmol L-1 and 1.0 to 12.0 mmol L-1 by cyclic voltammetry, respectively. The proposed method showed excellent anti-interferences ability with good selectivity and was successful used for quantitative detection of real samples, which displayed the potential applications to develop into a new analytical device.

Photoelectrochemical aptasensor for lead(II) by exploiting the CdS nanoparticle-assisted photoactivity of TiO2 nanoparticles and by using the quercetin-copper(II) complex as the DNA intercalator.

A photoelectrochemical (PEC) aptasensor for Pb(II) detection is described. A nanocomposite consisting of CdS (2.5 µm) and TiO2 nanoparticles (10 nm) was used as a photoactive material, and gold nanochains (Au NCs) as the support for immobilization of the Pb(II)-binding aptamer. The quercetin-copper(II) complex was further employed as the intercalator for the improvement of the photoactivity by embedding it into dsDNA. In the presence of Pb(II), a Pb(II)-stabilized G-quadruplex was formed between Pb(II) and DNA S1. This is accompanied by unwinding of the dsDNA and the release of the quercetin-copper(II) complex from the surface of the sensor. This results in a decrease of the photocurrent that drops linearly from 5.0 × 10-12 to 1.0 × 10-8 mol·L-1 Pb(II) concentration range with a detection limit of 1.6 × 10-12 mol·L-1. The method was applied to the determination of Pb(II) in various samples and gave satisfactory results. Graphical abstractA photoelectrochemical aptasensor was fabricated for the detection of Pb(II) based on CdS-TiO2 nanocomposite modified indium tin oxide (ITO) electrode. Gold nanochains (AuNCs) were used as anchor to immobilize the aptamers S1 and S2 that form a double helix structure by DNA hybridization. After embedding of quercetin-copper(II) complex as intercalator and electron donor, the concentrations of Pb(II) were determined by the changes of photocurrents.