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1.
J Am Chem Soc ; 146(30): 21147-21159, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39013150

RESUMO

Driven by the essential need of a green, safe, and low-cost approach to producing H2O2, a highly valuable multifunctional chemical, artificial photosynthesis emerges as a promising avenue. However, current catalyst systems remain challenging, due to the need of high-density sunlight, poor selectivity and activity, or/and unfavorable thermodynamics. Here, we reported that an indirect 2e- water oxidation reaction (WOR) in photocatalytic H2O2 production was unusually activated by C5N2 with piezoelectric effects. Interestingly, under ultrasonication, C5N2 exhibited an overall H2O2 photosynthesis rate of 918.4 µM/h and an exceptionally high solar-to-chemical conversion efficiency of 2.6% after calibration under weak light (0.1 sun). Mechanism studies showed that the piezoelectric effect of carbon nitride overcame the high uphill thermodynamics of *OH intermediate generation, which enabled a new pathway for 2e- WOR, the kinetic limiting step in the overall H2O2 production from H2O and O2. Benefiting from the outstanding sonication-assisted photocatalytic H2O2 generation under weak light, the concept was further successfully adapted to biomedical applications in efficient sono-photochemodynamic therapy for cancer treatment and water purification.

2.
Small ; : e2406374, 2024 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-39285809

RESUMO

Electrochemiluminescence (ECL) is a powerful tool for clinical diagnosis due to its exceptional sensitivity. However, the standard tripropylamine (TPrA) coreactant for Ru(bpy)3Cl2, the most widely studied and used ECL system, is highly toxic. Despite extensive research on alternative coreactants, they often fall short in poor efficiency. From a reaction kinetics perspective, accelerating electrooxidation rate of Ru(bpy)3Cl2 is an essential way to compensate the efficiency limitation of coreactants, but is rarely reported. Here, a hybrid electrocatalyst@coreactant dots for the ECL of Ru(bpy)3Cl2 is reported. The as-prepared WSe2@bovine serum albumin (WSe2@BSA) dots is biocompatible, and demonstrate dual functions, i.e., the BSA shell works as a coreactant, meanwhile, the WSe2 core effectively catalyzes Ru(bpy)3Cl2 oxidation. As a result, WSe2@BSA dots exhibit an exceptionally high efficiency comparable to TPrA for the ECL of Ru(bpy)3Cl2. In addition, the procedure for synthesizing WSe2@BSA dots is facile (room temperature, atmospheric conditions), rapid (5 min), and scalable (for millions of bioassays). A biosensor utilizing WSe2@BSA dots shows promise for highly sensitive detecting glypican-3 in clinical liver cancer serum samples, especially for alpha-fetoprotein-negative patients. This work opens a new avenue for developing a highly efficient ECL system for biosensing and clinical diagnosis.

3.
Anal Bioanal Chem ; 416(17): 3859-3867, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38613684

RESUMO

Electrochemiluminescence (ECL) is a luminescence production technique triggered by electrochemistry, which has emerged as a powerful analytical technique in bioanalysis and clinical diagnosis. During ECL, charge transfer (CT) is an important process between electrochemical excitation and luminescent emission, and dramatically affects the efficiency of exciton generation, playing a pivotal role in the light-emitting properties of nanomaterials. Reticular framework materials with intramolecular/intermolecular interactions offer a promising platform for regulating CT pathways and enhancing luminescence efficiency. Deciphering the role of intramolecular/intermolecular CT processes in reticular framework materials allows for the targeted design and synthesis of emitters with precisely controlled CT properties. This sheds light on the microscopic mechanisms of electro-optical conversion in ECL, propelling advancements in their efficiency and breakthrough applications. This mini-review focuses on recent advancements in engineering CT within reticular frameworks to boost ECL efficiency. We summarized strategies including intra-reticular charge transfer, CT between the metal and ligands, and CT between guest molecules and frameworks within reticular frameworks, which holds promise for developing next-generation ECL devices with enhanced sensitivity and light emission.

4.
BMC Public Health ; 24(1): 1823, 2024 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-38977991

RESUMO

BACKGROUND: Medical disputes, which are prevalent in China, are a growing global public health problem. The Chinese government has proposed third-party mediation (TPM) to resolve this issue. However, the characteristics, efficiency, and influencing factors of TPM in resolving medical disputes in public hospitals in China have yet to be determined. METHODS: We conducted a systematic study using TPM records from medical disputes in Gansu Province in China from 2014 to 2019. A χ2 test was used to compare differences between groups, and binary logistic analysis was performed to determine the factors influencing the choice of TPM for resolving medical disputes. RESULTS: We analyzed 5,948 TPM records of medical disputes in Gansu Province in China. The number of medical disputes and the amount of compensation awarded in public hospitals in the Gansu Province increased annually from 2014 to 2019, with most of the disputes occurring in secondary and tertiary hospitals. Approximately 89.01% of the medical disputes were handled by TPM; the average compensation amount with TPM was Chinese Yuan (CNY) 48,688.73, significantly less than that awarded via court judgment and judicial mediation. TPM was more likely to succeed in settling medical disputes in the < CNY10,000 compensation group than in the no-compensation group (odds ratio [OR] = 3.14, 95% confidence interval [CI] 1.53-6.45). However, as the compensation amount increased, the likelihood of choosing TPM decreased significantly. Moreover, TPM was less likely to be chosen when medical disputes did not involve death (OR = 0.49, 95% CI 0.36-0.45) or when no-fault liability was determined (vs. medical accidents; OR = 0.37, 95% CI 0.20-0.67). CONCLUSION: Our findings demonstrate that TPM mechanisms play a positive role in efficiently reducing compensation amounts and increasing medical dispute resolution rates which was the main settlement method in resolving medical disputes in public hospitals of Gansu Province in China. TPM could help greatly reduce conflicts between doctors and patients, avoid litigation, and save time and costs for both parties. Moreover, compensation amounts, non-fatal outcomes, and no-fault liability determinations influence the choice of TPM for settling medical disputes.


Assuntos
Dissidências e Disputas , Hospitais Públicos , Negociação , Humanos , Hospitais Públicos/estatística & dados numéricos , China , Masculino , Feminino
5.
Psychol Health Med ; 29(3): 492-504, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36916209

RESUMO

As the mainstay of healthcare, the job satisfaction of medical staff deserves attention. This study aimed to explore the correlation between the perception of the high-performance work system (P-HPWS) and job satisfaction of medical staff in public hospitals and to further investigate the mediating effect of self-efficacy. From November 2019 to January 2020, a cross-sectional survey on working doctors and nurses was conducted in five tertiary public hospitals in China. A total of 520 participants were surveyed. The P-HPWS, job satisfaction, and self-efficacy were assessed using the 25-item self-administered scale, six-item job satisfaction questionnaire, and the General Self-Efficacy Scale, respectively. Linear regression and mediation effects models were used to identify the associations between primary variables. The results showed a significant positive correlation between P-HPWS and job satisfaction (P < 0.01), while self-efficacy played a mediating role between P-HPWS and job satisfaction. This finding reveals the benefits of improving employees' P-HPWS and self-efficacy on their job satisfaction, and that hospitals can improve their management systems by implementing and refining HPWS.


Assuntos
Atenção à Saúde , Autoeficácia , Humanos , Estudos Transversais , Inquéritos e Questionários , Corpo Clínico , Hospitais Públicos , Satisfação no Emprego
6.
Angew Chem Int Ed Engl ; 63(36): e202408935, 2024 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-38895986

RESUMO

Reactive oxygen species (ROS) regulation for single-atom nanozymes (SAzymes), e.g., Fe-N-C, is a key scientific issue that determines the activity, selectivity, and stability of aerobic reaction. However, the poor understanding of ROS formation mechanism on SAzymes greatly hampers their wider deployment. Herein, inspired by cytochromes P450 affording bound ROS intermediates in O2 activation, we report Fe-N-C containing the same FeN4 but with tunable second-shell coordination can effectively regulate ROS production pathways. Remarkably, compared to the control Fe-N-C sample, the second-shell sulfur functionalized Fe-N-C delivered a 2.4-fold increase of oxidase-like activity via the bound Fe=O intermediate. Conversely, free ROS (⋅O2 -) release was significantly reduced after functionalization, down to only 17 % of that observed for Fe-N-C. The detailed characterizations and theoretical calculations revealed that the second-shell sulfur functionalization significantly altered the electronic structure of FeN4 sites, leading to an increase of electron density at Fermi level. It enhanced the electron transfer from active sites to the key intermediate *OOH, thereby ultimately determining the type of ROS in aerobic oxidation process. The proposed Fe-N-Cs with different second-shell anion were further applied to three aerobic oxidation reactions with enhanced activity, selectivity, and stability.

7.
Anal Chem ; 95(44): 16407-16417, 2023 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-37883696

RESUMO

Regulation of the reaction pathways is a perennial theme in the field of chemistry. As a typical chromogenic substrate, 3,3',5,5'-tetramethylbenzidine (TMB) generally undertakes one-electron oxidation, but the product (TMBox1) is essentially a confused complex and is unstable, which significantly hampers the clinic chromogenic bioassays for more than 50 years. Herein, we report that sodium dodecyl sulfate (SDS)-based micelles could drive the direct two-electron oxidation of TMB to the final stable TMBox2. Rather than activation of H2O2 oxidant in the one-electron TMB oxidation by common natural peroxidase, activation of the TMB substrate by SDS micelles decoupled the thermodynamically favorable complex between TMBox2 with unreacted TMB, leading to an unusual direct two-electron oxidation pathway. Mechanism studies demonstrated that the complementary spatial and electrostatic isolation effects, caused by the confined hydrophobic cavities and negatively charged outer surfaces of SDS micelles, were crucial. Further cascading with glucose oxidase, as a proof-of-concept application, allowed glucose to be more reliably measured, even in a broader range of concentrations without any conventional strong acid termination.


Assuntos
Peróxido de Hidrogênio , Micelas , Oxirredução , Peroxidase/metabolismo , Benzidinas/química , Colorimetria , Compostos Cromogênicos/química
8.
Anal Chem ; 95(16): 6620-6628, 2023 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-37040595

RESUMO

The development of electrochemiluminescence (ECL) emitters of different colors with high ECL efficiency (ΦECL) is appealing yet challenging for ultrasensitive multiplexed bioassays. Herein, we report the synthesis of highly efficient polymeric carbon nitride (CN) films with fine-tuned ECL emission from blue to green (410, 450, 470, and 525 nm) using the precursor crystallization method. More importantly, naked eye-observable and significantly enhanced ECL emission was achieved, and the cathodic ΦECL values were ca. 112, 394, 353, and 251 times those of the aqueous Ru(bpy)3Cl2/K2S2O8 reference. Mechanism studies showed that the density of surface-trapped electrons, the associated nonradiative decay pathways, and electron-hole recombination kinetics were crucial factors for the high ΦECL of CN. Based on high ΦECL and different colors of ECL emission, the wavelength-resolved multiplexing ECL biosensor was constructed to simultaneously detect miRNA-21 and miRNA-141 with superior low detection limits of 0.13 fM and 25.17 aM, respectively. This work provides a facile method to synthesize wavelength-resolved ECL emitters based on metal-free CN polymers with high ΦECL for multiplexed bioassays.


Assuntos
Técnicas Biossensoriais , MicroRNAs , Medições Luminescentes/métodos , Técnicas Eletroquímicas/métodos , Fotometria , Técnicas Biossensoriais/métodos , Polímeros
9.
Anal Chem ; 95(36): 13716-13724, 2023 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-37650675

RESUMO

Photoelectrochemical (PEC) sensing enables the rapid, accurate, and highly sensitive detection of biologically important chemicals. However, achieving high selectivity without external biological elements remains a challenge because the PEC reactions inherently have poor selectivity. Herein, we report a strategy to address this problem by regulating the charge-transfer pathways using polymeric carbon nitride (pCN)-based heterojunction photoelectrodes. Interestingly, because of redox reactions at different semiconductor/electrolyte interfaces with specific charge-transfer pathways, each analyte demonstrated a unique combination of photocurrent-change polarity. Based on this principle, a pCN-based PEC sensor for the highly selective sensing of ascorbic acid in serum against typical interferences, such as dopamine, glutathione, epinephrine, and citric acid was successfully developed. This study sheds light on a general PEC sensing strategy with high selectivity without biorecognition units by engineering charge-transfer pathways in heterojunctions on photoelectrodes.


Assuntos
Ácido Ascórbico , Ácido Cítrico , Dopamina , Engenharia
10.
Opt Lett ; 48(12): 3263-3266, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-37319077

RESUMO

Powerful 1.2-µm laser operation was produced in Ho3+-doped single-cladding, in-house fabricated ZrF4-BaF2-YF3-AlF3 (ZBYA) glass fibers. The fibers were fabricated based on ZBYA glass with a composition of ZrF4-BaF2-YF3-AlF3. Pumped by an 1150-nm Raman fiber laser, the maximum combined laser output power emitted from both sides of a 0.5-mol% Ho3+-doped ZBYA fiber was 6.7 W, with a slope efficiency of 40.5%. We also observed lasing at 2.9 µm with an output power of 350 mW, which was ascribed to the transition of Ho3+:5I6 → 5I7. The effect of rare earth (RE) doping concentration and the length of the gain fiber were also investigated to determine their effect on laser performance at 1.2 µm and 2.9 µm.


Assuntos
Terapia a Laser , Vidro
11.
J Nanobiotechnology ; 21(1): 467, 2023 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-38062518

RESUMO

Tumor cell-released LC3+ extracellular vesicles (LC3+ EVs) participate in immunosuppression during autophagy and contribute to the occurrence and development of breast cancer. In view of the strong association between the LC3+ EVs and breast cancer, developing an effective strategy for the quantitative detection of LC3+ EVs levels with high sensitivity to identify LC3+ EVs as new biomarkers for accurate diagnosis of breast cancer is crucial, but yet not been reported. Herein, an ultrasensitive electrochemical immunosensor is presented for the quantitative determination of LC3+ EVs using a three-dimensional graphene oxide hydrogel-methylene blue composite as a redox probe, showing a low detection limit and a wide linear range. With this immunosensor, the expression levels of LC3+ EVs in various practical sample groups including different cancer cell lines, the peripheral blood of tumor-bearing mice before and after immunotherapy, and the peripheral blood from breast cancer patients with different subtypes and stages were clearly distinguished. This study demonstrated that LC3+ EVs were superior as biomarkers for the accurate diagnosis of breast cancer compared to traditional biomarkers, particularly for cancer subtype discrimination. This work would provide a new noninvasive detection tool for the early diagnosis and prognosis assessment of breast cancer in clinics.


Assuntos
Técnicas Biossensoriais , Neoplasias da Mama , Vesículas Extracelulares , Humanos , Animais , Camundongos , Feminino , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/metabolismo , Hidrogéis , Biomarcadores Tumorais/metabolismo , Imunoensaio/métodos , Biomarcadores/metabolismo , Vesículas Extracelulares/metabolismo
12.
Hum Resour Health ; 21(1): 53, 2023 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-37386560

RESUMO

BACKGROUND: Medical disputes remain a global public health problem. However, an analysis of the characteristics and risk factors affecting the judgment results of medical damage liability disputes in second-instance and retrial cases in China has yet to be conducted. METHODS: We conducted a systematic search and evaluation of second-instance and retrial cases among all medical damage liability disputes in China Judgments Online; SPSS 22.0 was used for the statistical analysis. A χ2 test or likelihood ratio Chi-square test was used to compare differences between groups, and multivariate logistic regression analysis was performed to determine independent risk factors that could affect the judgment results of medical disputes. RESULTS: We included 3172 second-instance and retrial cases among all medical damage liability disputes in the analysis. The results showed that 48.04% of cases were unilateral appeals by the patient, and medical institutions were responsible for providing compensation in 80.64% of these cases. Cases involving compensation ranged from Chinese Yuan (CNY) 100 000 to 500 000 ranked first (40.95%); 21.66% were non-compensation cases. Cases involving mental damage compensation of less than CNY 20 000 accounted for 39.03%. Violations of medical treatment and nursing routines accounted for 64.25% of all cases. In addition, re-identification in 54.59% of cases changed the initial appraisal opinion. Independent risk factors for medical personnel to lose a lawsuit in a multivariate logistic regression model included appeal originator [patient side: OR = 18.809 (95% CI 11.854-29.845); both sides: OR = 22.168 (95% CI 12.249-40.117)], change of the original verdict (OR = 5.936, 95% CI 3.875-9.095), judicial identification (OR = 6.395, 95% CI 4.818-8.487), violations of medical treatment and nursing routines (OR = 8.783, 95% CI 6.658-11.588), and non-standard medical document writing (OR = 8.500, 95% CI 4.805-15.037). CONCLUSION: Our study clarifies the characteristics of second-instance and retrial cases among all medical damage liability disputes in China from multiple perspectives and identifies the independent risk factors for medical personnel losing a lawsuit. This study could help medical institutions prevent and reduce medical disputes, at the same time, it could be helpful for medical institutions to provide better medical treatment and nursing services for patients.


Assuntos
Dissidências e Disputas , Julgamento , Humanos , China , Pessoal de Saúde , Fatores de Risco
13.
Artigo em Inglês | MEDLINE | ID: mdl-37499852

RESUMO

OBJECTIVE: To determine the effectiveness of non-pharmacologic interventions and the additional benefits of their combination in patients with heart failure with reduced ejection fraction (HFrEF). DATA SOURCES: We searched PubMed, Embase, and the Cochrane Clinical Trials Register from the date of database inception to April 22, 2023. STUDY SELECTION: Randomized controlled trials involving non-pharmacologic interventions conducted in patients with HFrEF were included. DATA EXTRACTION: Data were extracted by 2 independent reviewers based on a pre-tested data extraction form. The quality of evidence was assessed using the Cochrane Risk of Bias tool and the Grading of Recommendations Assessment, Development, and Evaluation method. DATA SYNTHESIS: A total of 82 eligible studies (4574 participants) were included. We performed a random-effects model within a Bayesian framework to calculate weighted mean differences (WMDs) and 95% credibility intervals. High or moderate certainty evidence indicated that high-intensity aerobic interval training (HIAIT) was best on improving 6-minute walk distance (6MWD; 68.55 m [36.41, 100.47]) and left ventricular ejection fraction (6.28% [3.88, 8.77]), while high-intensity aerobic continuous training (HIACT) is best on improving peak oxygen consumption (Peak VO2; 3.48 mL/kg•min [2.84, 4.12]), quality of life (QOL; -17.26 [-29.99, -7.80]), resting heart rate (-8.20 bpm [-13.32, -3.05]), and N-terminal pro-B-type natriuretic peptide (-600.96 pg/mL [-902.93, -404.52]). Moderate certainty evidence supported the effectiveness of inspiratory muscle training to improve peak oxygen consumption and functional electrical stimulation to improve QOL. Moderate-intensity aerobic continuous training (MIACT) plus moderate-intensity resistance training (MIRT) had additional benefits in Peak VO2, 6MWD, and QOL. This review did not provide a comprehensive evaluation of adverse events. CONCLUSIONS: Both HIAIT and HIACT are the most effective single non-pharmacologic interventions for HFrEF. MIACT plus MIRT had additional benefits in improving peak oxygen consumption, 6MWD, and QOL.

14.
Sensors (Basel) ; 23(5)2023 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-36904637

RESUMO

Recent advances in training monitoring are centered on the statistical indicators of the concentric phase of the movement. However, those studies lack consideration of the integrity of the movement. Moreover, training performance evaluation needs valid data on the movement. Thus, this study presents a full-waveform resistance training monitoring system (FRTMS) as a whole-movement-process monitoring solution to acquire and analyze the full-waveform data of resistance training. The FRTMS includes a portable data acquisition device and a data processing and visualization software platform. The data acquisition device monitors the barbell's movement data. The software platform guides users through the acquisition of training parameters and provides feedback on the training result variables. To validate the FRTMS, we compared the simultaneous measurements of 30-90% 1RM of Smith squat lifts performed by 21 subjects with the FRTMS to similar measurements obtained with a previously validated three-dimensional motion capture system. Results showed that the FRTMS produced practically identical velocity outcomes, with a high Pearson's correlation coefficient, intraclass correlation coefficient, and coefficient of multiple correlations and a low root mean square error. We also studied the applications of the FRTMS in practical training by comparing the training results of a six-week experimental intervention with velocity-based training (VBT) and percentage-based training (PBT). The current findings suggest that the proposed monitoring system can provide reliable data for refining future training monitoring and analysis.


Assuntos
Treinamento Resistido , Humanos , Treinamento Resistido/métodos , Postura , Software , Transdutores , Monitorização Fisiológica , Arritmias Cardíacas , Força Muscular
15.
Psychol Health Med ; 28(3): 743-754, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-34623192

RESUMO

The purpose of this study was to explore the correlation between the perception of high performance work system (P-HPWS) and job burnout of nurses, further to detect the mediating effect of regulatory emotional self-efficacy (RES). From November 2019 to January 2020, a cross-sectional survey on working nurses was conducted in 5 hospitals in Lanzhou, China. A total of 1266 nurses were investigated. Demographics and perception of high performance work systems, job burnout, and RES were collected. The data were statistically processed using correlation analysis, multiple linear regression analysis, and a test of mediated moderation. The P-HPWS was significantly negatively correlated with job burnout (P < 0.01). The RES played a mediating effect between the perception of HPWS and job burnout. The results support the important role of P-HPWS in the remission of job burnout, and the hospital can improve its management by implementing and perfecting the HPWS.Abbreviations: P-HPWS: Perceived high-performance work system; RES: Regulatory emotional self-efficacy; POS: Perceived self-efficacy in expressing positive emotions; ANG: Perceived self-efficacy in managing anger/irritation; DES: Perceived self-efficacy in managing despondency/distress.


Assuntos
Esgotamento Profissional , Enfermeiras e Enfermeiros , Humanos , Estudos Transversais , Autoeficácia , Esgotamento Profissional/epidemiologia , Esgotamento Profissional/psicologia , Emoções , Inquéritos e Questionários , Satisfação no Emprego
16.
Angew Chem Int Ed Engl ; 62(44): e202312053, 2023 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-37698462

RESUMO

Copper nanoclusters (CuNCs) are emerging electrochemiluminescence (ECL) emitters with unique molecule-like electronic structures, high abundance, and low cost. However, the synthesis of CuNCs with high ECL efficiency and stability in a scalable manner remains challenging. Here, we report a facile gram-scale approach for preparing self-assembled CuNCs (CuNCsAssy ) induced by ligands with exceptionally boosted anodic ECL and stability. Compared to the disordered aggregates that are inactive in ECL, the CuNCsAssy shows a record anodic ECL efficiency for CuNCs (10 %, wavelength-corrected, relative to Ru(bpy)3 Cl2 /tripropylamine). Mechanism studies revealed the unusual dual functions of ligands in simultaneously facilitating electrochemical excitation and radiative transition. Moreover, the assembly addressed the limitation of poor stability of conventional CuNCs. As a proof of concept, an ECL biosensor for alkaline phosphatase detection was successfully constructed with an ultralow limit of detection of 8.1×10-6  U/L.


Assuntos
Técnicas Biossensoriais , Cobre , Cobre/química , Ligantes , Medições Luminescentes , Técnicas Eletroquímicas
17.
Angew Chem Int Ed Engl ; 62(27): e202302463, 2023 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-37144706

RESUMO

Ascorbate (H2 A) is a well-known antioxidant to protect cellular components from free radical damage and has also emerged as a pro-oxidant in cancer therapies. However, such "contradictory" mechanisms underlying H2 A oxidation are not well understood. Herein, we report Fe leaching during catalytic H2 A oxidation using an Fe-N-C nanozyme as a ferritin mimic and its influence on the selectivity of the oxygen reduction reaction (ORR). Owing to the heterogeneity, the Fe-Nx sites in Fe-N-C primarily catalyzed H2 A oxidation and 4 e- ORR via an iron-oxo intermediate. Nonetheless, trace O2 ⋅- produced by marginal N-C sites through 2 e- ORR accumulated and attacked Fe-Nx sites, leading to the linear leakage of unstable Fe ions up to 420 ppb when the H2 A concentration increased to 2 mM. As a result, a substantial fraction (ca. 40 %) of the N-C sites on Fe-N-C were activated, and a new 2+2 e- ORR path was finally enabled, along with Fenton-type H2 A oxidation. Consequently, after Fe ions diffused into the bulk solution, the ORR at the N-C sites stopped at H2 O2 production, which was the origin of the pro-oxidant effect of H2 A.

18.
Angew Chem Int Ed Engl ; 62(12): e202217078, 2023 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-36591995

RESUMO

Facile evaluation of oxygen reduction reaction (ORR) kinetics for electrocatalysts is critical for sustainable fuel-cell development and industrial H2 O2 production. Despite great success in ORR studies using mainstream strategies, such as the membrane electrode assembly, rotation electrodes, and advanced surface-sensitive spectroscopy, the time and spatial distribution of reactive oxygen species (ROS) intermediates in the diffusion layer remain unknown. Using time-dependent electrochemiluminescence (Td-ECL), we report an intermediate-oriented method for ORR kinetics analysis. Owing to multiple ultrasensitive stoichiometric reactions between ROS and the ECL emitter, except for electron transfer numbers and rate constants, the potential-dependent time and spatial distribution of ROS were successfully obtained for the first time. Such exclusively uncovered information would guide the development of electrocatalysts for fuel cells and H2 O2 production with maximized activity and durability.

19.
Anal Chem ; 94(7): 3296-3302, 2022 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-35143169

RESUMO

Due to near-zero optical background and photobleaching, electrochemiluminescence (ECL), an optical phenomenon excited by electrochemical reactions, has drawn extensive attention, especially for ultrasensitive bioassays. Developing diverse ECL emitters is crucial to unlocking their multiformity and performances but remains a formidable challenge due to the rigorous requirements for ECL. Herein, we report a general strategy to light up ECL-inactive dyes in an aqueous solution via grafting, a well-developed concept for plant propagation since 500 BCE. As a proof of concept, a series of luminol donor-dye acceptor-based ECL emitters were grafted with near-unity resonance energy transfer (RET) efficiency and coarse/fine-tunable emission wavelengths. Rather than the sophisticated design of new skeleton-based molecules to meet all of the prerequisites for ECL in a constrained manner, each unit in the proposed ECL ensemble performed its functions maximally. As a result, beyond traditional two-dimensional (2D) ones, a three-dimensional (3D) coordinate biosensing system, simultaneously showing a calibration curve and selectivity, was established using the new ECL emitter. This lighting up strategy would generally address the scarcity of ECL emitters and enable unprecedented functions.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Técnicas Biossensoriais/métodos , Corantes , Técnicas Eletroquímicas/métodos , Transferência de Energia , Medições Luminescentes/métodos
20.
Anal Chem ; 94(47): 16510-16518, 2022 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-36374940

RESUMO

Tuning the electrochemiluminescence (ECL) wavelength of carbon dots (CDs) with enhanced efficiency is essential for multiplexed biosensing, bioimaging, and energy applications but remains challenging. Herein, we reported a facile route to finely modulate the ECL wavelength of CDs from 425 to 645 nm, the widest range ever reported, along with a more than 5-fold enhancement of ECL efficiency via phosphorous (P) incorporation. The molecular mechanism was explored experimentally and theoretically, which revealed the unusual dual roles of P dopants in the form of P-C and P-O bonding, that is, importing shallow trapping states and promoting an effective intramolecular charge transfer. This work would allow unlocking the key factors of ECL kinetics for heteroatom-doped CDs appearing out of reach and open a new avenue for the rational design of nanocarbon for desirable applications.


Assuntos
Técnicas Biossensoriais , Pontos Quânticos , Carbono , Medições Luminescentes/métodos , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos
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