Computational identification and experimental verification of a novel signature based on SARS-CoV-2-related genes for predicting prognosis, immune microenvironment and therapeutic strategies in lung adenocarcinoma patients.

Background: Early research indicates that cancer patients are more vulnerable to adverse outcomes and mortality when infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nonetheless, the specific attributes of SARS-CoV-2 in lung Adenocarcinoma (LUAD) have not been extensively and methodically examined. Methods: We acquired 322 SARS-CoV-2 infection-related genes (CRGs) from the Human Protein Atlas database. Using an integrative machine learning approach with 10 algorithms, we developed a SARS-CoV-2 score (Cov-2S) signature across The Cancer Genome Atlas and datasets GSE72094, GSE68465, and GSE31210. Comprehensive multi-omics analysis, including assessments of genetic mutations and copy number variations, was conducted to deepen our understanding of the prognosis signature. We also analyzed the response of different Cov-2S subgroups to immunotherapy and identified targeted drugs for these subgroups, advancing personalized medicine strategies. The expression of Cov-2S genes was confirmed through qRT-PCR, with GGH emerging as a critical gene for further functional studies to elucidate its role in LUAD. Results: Out of 34 differentially expressed CRGs identified, 16 correlated with overall survival. We utilized 10 machine learning algorithms, creating 101 combinations, and selected the RFS as the optimal algorithm for constructing a Cov-2S based on the average C-index across four cohorts. This was achieved after integrating several essential clinicopathological features and 58 established signatures. We observed significant differences in biological functions and immune cell statuses within the tumor microenvironments of high and low Cov-2S groups. Notably, patients with a lower Cov-2S showed enhanced sensitivity to immunotherapy. We also identified five potential drugs targeting Cov-2S. In vitro experiments revealed a significant upregulation of GGH in LUAD, and its knockdown markedly inhibited tumor cell proliferation, migration, and invasion. Conclusion: Our research has pioneered the development of a consensus Cov-2S signature by employing an innovative approach with 10 machine learning algorithms for LUAD. Cov-2S reliably forecasts the prognosis, mirrors the tumor's local immune condition, and supports clinical decision-making in tumor therapies.

Dynamic and Asymmetrical Ion Concentration Polarization in Dual Nanopipettes.

Dual nanopipettes with two channels have been receiving great attention due to the convenient experimental setup and multiple measuring channels in sensing applications at nanoscale, while the involved dynamic and asymmetrical ion transport processes have not been fully elucidated. In this paper, both experimental and simulation methods are used to investigate the dynamic mass transport processes inside dual nanopipettes with two well-separated channels. The results present that the ion transport resistance through the two channels (R12) is always the add-up of the individual ones (R13 + R23) with respect to the bulk solutions, at various ionic strengths and scan rates. A constant zero-current potential is obtained when loading an asymmetrical electrolyte concentration in the two channels, and the zero-potential current displays a good linear relationship with the bulk concentration outside the pipet. Besides revealing the dynamic and asymmetrical concentration polarization in the dual nanopipettes, these results would also further promote the better usage of dual nanopipettes in electrochemical sensing and imaging applications.

Meta-analysis of the effectiveness and safety of robotic-assisted versus laparoscopic transabdominal preperitoneal repair for inguinal hernia.

BACKGROUND: Inguinal hernia is a common global disease. This study aims to investigate the effectiveness and safety of robot-assisted transabdominal preperitoneal repair (RTAPP) and laparoscopic transabdominal preperitoneal repair (LTAPP) for inguinal hernia. METHODS: We conducted a thorough search in Cochrane Library, Embase, and PubMed for relevant clinical studies. After applying inclusion and exclusion criteria, the quality of selected studies was assessed using the Jadad scale for randomized controlled studies and the Newcastle-Ottawa scale for observational studies. Meta-analysis was performed using RevMan 5.3 software. RESULTS: A total of ten studies were included, comprising two randomized controlled studies and eight non-randomized controlled studies. Meta-analysis results revealed no statistically significant differences between the RTAPP group and the LTAPP group regarding hospital stay [MD = 0.21 days, 95% CI (-0.09, 0.51), P = 0.17], incidence of seroma [OR = 0.85, 95% CI(0.45, 1.59), P = 0.61], overall complication rate [OR = 1.22, 95% CI(0.68, 2.18), P = 0.51], readmission rate [OR = 1.31, 95% CI(0.23, 7.47), P = 0.76], and recurrence rate [OR = 0.82, 95% CI(0.22, 3.07), P = 0.77]. However, the RTAPP group had longer operation time compared to the LTAPP group [MD = 14.02 minutes, 95% CI (6.65, 21.39), P = 0.0002], and the cost of the RTAPP procedure was higher than that of the LTAPP procedure [MD = $4.17 thousand, 95% CI (2.59, 5.76), P<0.00001]. CONCLUSION: RTAPP for inguinal hernia is a safe and feasible approach, however, it is associated with increased operation time and treatment costs.

Tunneling Electron Transfer across Cell Membrane via Au Nanoparticles in Single Living Cells.

Herein, we present a new and simple electrochemical method to detect the intracellular electroactive substances by utilizing the electron tunnelling processes at the metal nanoparticles inside the cells. Intriguing discrete oxidation and reduction current spikes are obtained when testing the cells with loaded Au nanoparticles at the ultramicroelectrodes, which should come from reactive oxygen species (ROS) inside the single cell. The charges enclosed in the current spikes represent the ROS content inside the living cells, as confirmed by the fluorescence studies. As this simple electron tunnelling approach needs no nanoelectrodes or nanotip penetration processes, we believe it could have great potential applications in electrochemical analysis of single living cells.

An ultra-sensitive platinized nanocavity electrode for analysis of cytosolic catecholamines in one living cell.

The catecholamines, mainly dopamine (DA), are present in the cellular cytosol with low abundance, while, play key roles in various neurodegenerative disorders. Here, platinized nanocavity carbon electrodes are employed to analyze cytosolic catecholamines in a single living PC12 cell, which is not easily quantified using the classic electrodes. The confined structure and excellent conductivity in the platinized nanocavity accelerate the electron transfer of the DA, resulting in a low detection limit down to 50 nM. The sensitivity of DA detection is improved to be 10.73 pA mM-1 nm-1 in the response range of 50 nM-100 µM, which guarantees quantitative analysis of cytosolic catecholamines with low abundance. Eventually, the platinized nanocavity electrode is employed to detect cytosolic catecholamines in a single PC12 cell without an obvious interruption of cellular catecholamine level. The cytosolic catecholamines in a single PC12 cell is measured in situ to be 0.1 µM, which is achieved for the first time at the single cell level using the electrochemical method. The results demonstrate that the nanocavity electrode with a high sensitivity could offer a promising means to dynamically track catecholamines in a single cell.

Effectiveness and safety of different doses of febuxostat compared with allopurinol in the treatment of hyperuricemia: a meta-analysis of randomized controlled trials.

BACKGROUND: The prevalence of hyperuricemia has increased steadily with the continuous improvement of living standards. Some studies have reported the clinical effectiveness and safety of different doses of febuxostat in comparison with allopurinol in hyperuricemia treatment, but the sample sizes of the studies have been small, and the results have been inconsistent. We designed this meta-analysis to evaluate the effectiveness and safety of different doses of febuxostat compared with allopurinol in the treatment of hyperuricemia. METHODS: The Cochrane Library, Embase, PubMed, Web of Science and ClinicalTrials.gov databases were searched to identify randomized controlled trials (RCTs) comparing the use of febuxostat and allopurinol for the treatment of hyperuricemia. The effectiveness and safety of different doses of febuxostat and allopurinol in treating hyperuricemia were assessed using meta-analysis. RESULTS: A total of 11 randomized controlled trials were included in the meta-analysis. The results of the meta-analysis showed that the percentage of patients achieving serum uric acid levels of 6.0 mg/dL or less was higher among patients taking febuxostat (80 mg/d) than among patients taking allopurinol (200-300 mg/d) [RR = 1.79, 95% CI (1.55, 2.08), P < 0.00001]. However, there was no statistically significant difference in the percentage of patients achieving serum uric acid levels of 6.0 mg/dL or less between febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 1.10, 95% CI (0.93, 1.31), P = 0.25]. There was also no statistically significant difference in the incidence of gout between the febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 0.97, 95% CI (0.64, 1.49), P = 0.91] or between the febuxostat (80 mg/d) and allopurinol (200-300 mg/d) [RR = 1.13, 95% CI (0.81, 1.58), P = 0.48].No significant difference in the incidence of major adverse reactions as observed between the febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 1.16; 95% CI (0.43, 3.16), P = 0.77] or between the febuxostat (80 mg/d) and allopurinol (200-300 mg/d) [RR = 1.06; 95% CI (0.79, 1.42), P = 0.70]. The incidence of adverse cardiovascular events did not differ significantly between the febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 1.30; 95% CI (0.57, 2.95), P = 0.53] or between the febuxostat (80 mg/d) and allopurinol (200-300 mg/d) [RR = 1.79; 95% CI (0.74, 4.32), P = 0.20]. CONCLUSIONS: Febuxostat (80 mg/d) was associated with a higher percentage of patients achieving serum uric acid levels of 6.0 mg/dL or less than allopurinol (200-300 mg/d), however, febuxostat (80 mg/d) did not exhibit better efficacy in reducing the incidence of gout. More attention should be devoted to the adverse reactions caused by an increase in febuxostat doses.

Safety of unfixed mesh in laparoscopic total extraperitoneal inguinal hernia repair: A meta-analysis of randomized controlled trials.

Background: Whether the effect of the unfixed mesh during laparoscopic total extraperitoneal (TEP) inguinal hernia repair can lead to hernia recurrence remains controversial. Methods: The PubMed, Cochrane Library, and EMBASE databases were searched to retrieve clinical randomized controlled trials (RCTs) comparing nonfixation of mesh and fixation of mesh in TEP inguinal hernia repair, and we performed a metaanalysis with RevMan 5.3 software. Results: Fifteen RCTs were included in the metaanalysis, which showed that the operation time (P = 0.001) of the unfixed mesh group was shorter than that of the fixed mesh group; additionally, the postoperative 24-h pain score (P = 0.04) and incidence of urinary retention (P = 0.001) were lower in the unfixed mesh group. There was no significant difference between the unfixed mesh group and the fixed mesh group in terms of hospital stay (P = 0.47), time to resume normal activities (P = 0.51), incidence of haematoma (P = 0.96), incidence of chronic pain (P = 0.20), and recurrence rate (P = 0.09). Conclusion: Unfixed mesh in TEP inguinal hernia repair shows no elevated recurrence rates compared to fixed mesh and is clinically safe.

Effect of cell settlement on the electrochemical collision behaviors of single microbes.

Electrochemical collision technique has emerged as a powerful approach to detect the intrinsic properties of single entities. The diffusion model, together with migration and convection processes are generally used to describe the transport and collision processes of single entities. However, things become more complicated concerning microbes because of their relatively large size, inherent motility and biological activities. In this work, the electrochemical collision behaviors of four different microorganisms: Escherichia coli (Gram-negative bacteria), Staphylococcus aureus, Bacillus subtilis (Gram-positive bacteria) and Saccharomyces cerevisiae (fungus) were systematically detected and compared using a blocking strategy. By using K4Fe(CN)6 as redox probe, the downwards step-like signals were recorded in the collision process of all the three bacteria, whereas the collision of S. cerevisiae was rarely detected. To further investigate the underlying reason for the abnormal collision behavior of S. cerevisiae, the effect of cell settlement was discussed. The results indicated that ellipsoidal S. cerevisiae with a cell size larger than 2 µm exhibited a cell sedimentation rate of 261.759 nm s-1, which is dozens of times higher than the other three bacteria. By further enhanced convection near the microelectrode or positioned the microelectrode at the bottom of electrochemical cell, the collision signals of S. cerevisiae were successfully detected, indicating cell sedimentation is a nonnegligible force in large cell transport. This study fully addressed the effect of cell settlement on the transport of microbial cells and provided two strategies to counteract this effect, which benefit for the deeper understanding and further application of electrochemical collision technique in single-cell detection.

Elucidating the Shape of Current Transients in Electrochemical Resistive-Pulse Sensing of Single Liposomes.

Electrochemical resistive-pulse (ERP) sensing with conductive carbon nanopipettes (CNPs) has recently been developed and employed for the detection of single liposomes and biological vesicles, and for the analysis of redox molecules contained in such vesicles. However, the origins of different shapes of current transients produced by the translocation of single vesicles through the CNP remain poorly understood. Herein, we report extensive finite-element simulations of both portions of an ERP transient, the current blockage by a vesicle approaching and passing through the pipet orifice and the faradaic current spike due to oxidation/reduction of redox species released from a vesicle on the carbon surface, for different values of parameters defining the geometry and dynamics of the vesicle/CNP system. The effects of the pipet geometry, surface charge, transport, vesicle trajectory, and collision location on the shape of current transients are investigated. The possibility of quantitative analysis of experimental ERP transients produced by translocations of liposomes and extracellular vesicles by fitting them to simulated curves is demonstrated. The developed theory can enable a more reliable interpretation of complicated ERP signals and characterization of the size and contents of single biological and artificial vesicles.

Molecular Electrocatalytic Processes in Carbon Nanopipettes.

Conductive nanopipettes have been recognized as powerful multifunctional platforms for electrochemical sensing applications in confined spaces. However, the electron-transfer processes of many biological analytes (i.e., enzymes or proteins) are slow and coupled with chemical reactions, which have not been well elucidated in conductive nanopipettes. In this Letter, both experimental and simulation methods are used to study electron-transfer processes coupled to chemical reactions (EC mechanism) in carbon nanopipettes (CNPs). It is demonstrated that the electroactive species can serve as redox mediator to help oxidize and reduce the nonelectroactive analytes of interest in the solution and produce noticeable catalytic current signals. Besides, glutathione was directly measured by using ferrocenemethanol as the redox mediator in the CNPs. The elucidated EC processes in CNPs would offer a new opportunity to measure nonelectroactive analytes in biological fields.

Meta­analysis of single-incision laparoscopic versus multi-trocar laparoscopic totally extraperitoneal inguinal hernia repair.

Whether single-incision laparoscopic totally extraperitoneal (SIL-TEP) inguinal hernia repair is similar or superior to multi-trocar laparoscopic totally extraperitoneal (MTL-TEP) inguinal hernia repair is controversial. We conducted this meta-analysis to compare the safety, efficacy and cosmetic effect of the two surgical methods. We systematically searched the Cochrane Library, Embase database and PubMed database for published studies on SIL-TEP and MTL-TEP inguinal hernia repair. The studies were screened and evaluated for quality according to the inclusion and exclusion criteria, and RevMan 5.3 software was used for meta-analysis. Twenty studies were included, including 7 randomized controlled studies and 13 nonrandomized controlled studies. Meta-analysis revealed no significant difference between SIL-TEP and MTL-TEP inguinal hernia repair in terms of unilateral operation time (P = 0.12), bilateral operation time (P = 0.72), pain score on the first day after operation (P = 0.61], chronic pain rate (P = 0.61), total complication rate (P = 0.26), hospital stay (P = 0.72), and recurrence rate (P = 0.83), but the cosmetic effect score (P = 0.002) was higher in the former. These findings demonstrate that SIL-TEP inguinal hernia repair is safe, reliable and feasible. In addition, it can result in a better cosmetic effect of the incision than MTL-TEP inguinal hernia repair. SIL-TEP inguinal hernia repair should be considered for patients with stricter cosmetic requirements.Clinical trial registration: INPLASY2022110085.

Efficacy and safety of ilioinguinal neurectomy in open tension-free inguinal hernia repair: A meta-analysis of randomized controlled trials.

BACKGROUND: There is still controversy surrounding routine ilioinguinal neurectomy in open tension-free inguinal hernia repair. METHOD: PubMed, Cochrane Library and EMBASE databases were searched for randomized controlled trials of ilioinguinal neurectomy in open tension-free inguinal hernia repair. Revman 5.3 software was used for meta-analysis. RESULT: Meta-analysis revealed that the incidence of severe pain on the first postoperative day was lower in the ilioinguinal neurectomy group (ING) than in the ilioinguinal nerve preservation group (INPG) [P < 0.0001]. The incidence of no pain in the first month postoperatively [P = 0.0004], the incidence of no pain in the sixth months postoperatively [P < 0.00001], and the numbness incidence in the first month postoperatively [P = 0.001] in the ING was higher than that in the INPG. There was no significant difference in the incidence of severe pain in the first month postoperatively [P = 0.20], the numbness incidence in the sixth postoperative month [P = 0.05], the hypoesthesia incidence in the first [P = 0.15] and sixth [P = 0.85] postoperative months between the two groups. CONCLUSION: Ilioinguinal neurectomy in open tension-free inguinal hernia repair can better prevent postoperative pain.

Nanoprecipitated CoPi enhanced photoelectrochemical water oxidation toward sensitive and selective Co2+ detection.

The detection of heavy metal ions Co2+ is of great significance to the environment and human health. Herein, a simple, highly selective and sensitive photoelectrochemical detection strategy for Co2+ was developed based on the enhanced activity by nanoprecipitated CoPi on the Au nanoparticle decorated BiVO4 electrode. The new photoelectrochemical sensor has a low detection limit of 0.03 µΜ and wide detection range of 0.1-10, and 10-6000 µΜ, with a high selectivity over other metal ions. The Co2+ concentration in tap water and commercial drinking water has also been successfully determined with the proposed method. Scanning electrochemical microscopy technique was employed to characterize the photocatalytic performance and heterogenous electron transfer rate of electrodes in situ, further revealing the photoelectrochemical sensing mechanism. Besides determining Co2+ concentration, this approach of enhanced catalytic activity by nanoprecipitation can be further extended to develop a variety of electrochemical, photoelectrochemical and optical sensing platforms for many other hazardous ions and biological molecules.

FOXM1/NCAPH activates glycolysis to promote colon adenocarcinoma stemness and 5-FU resistance.

Chemotherapy using 5-fluorouracil (5-FU) is currently considered the most effective treatment for advanced colon adenocarcinoma (COAD). However, drug resistance remains a major obstacle in treating COAD. Non-SMC condensin I complex subunit H ( NCAPH ) is known to have a certain impact on the development of COAD, but its precise involvement in the mechanism of 5-FU resistance has not been demonstrated. Bioinformatics analysis was utilized to assay the expression of NCAPH and Forkhead box M1 ( FOXM1 ) in COAD tumor tissues, which was then verified in COAD cell lines. The resistance of COAD cells to 5-FU was measured by CCK-8 assay, stemness was tested by cell sphere formation assay, and glycolysis ability was measured by cellular energy analysis metabolism. Chromatin Immunoprecipitation and dual-luciferase reporter assays were done to confirm the specific interaction between FOXM1 and NCAPH . The expression levels of FOXM1 and NCAPH were significantly upregulated in COAD tissues and cells, and they were involved in regulating the glycolytic signaling pathway. Inhibition of the glycolytic pathway could reverse the effect of NCAPH overexpression on COAD stemness and resistance. FOXM1 was identified as a transcription factor of NCAPH , and it regulated COAD glycolysis, cell stemness, and 5-FU resistance by activating NCAPH expression. FOXM1-mediated upregulation of NCAPH expression promoted COAD cell stemness and resistance via the glycolytic pathway. This study provides a possible mechanism for the FOXM1/NCAPH axis in the glycolytic pathway, cell stemness, and resistance in COAD.

Kosakonia radicincitans with hypervirulent lON genes causes human bloodstream infections.

Kosakonia radicincitans is a species within the new genus Kosakonia, which is typically a plant pathogen, with rare reports of human infection. The number of human infections may be underestimated because this new genus is under-represented among diagnostic tools. This report describes a case of bloodstream infection caused by K. radicincitans. The pathogen was identified by matrix-assisted laser desorption/ionization-TOF mass spectrometry and 16S rRNA gene sequencing. The hypervirulent human pathogenicity gene LON, which has not been described before, was detected in the bacterial genome by gene annotation. Thus, this discovery provides a new reference for studying the pathogenic mechanism of this rare pathogen.

Efficacy and safety of glue mesh fixation for laparoscopic inguinal hernia: A meta-analysis of randomized controlled trials.

It is still controversial whether glue can be used for mesh fixation in laparoscopic inguinal hernia repair. The aim of this meta-analysis was used to systematically evaluate the effectiveness and safety of glue mesh fixation in laparoscopic tension-free inguinal hernia repair. The PubMed database, EMBASE database and Cochrane Library were searched to collect published randomized controlled trials (RCTs) on laparoscopic tension-free inguinal hernia repair with glue mesh fixation. Sixteen RCTs and 2409 patients with inguinal hernia were included. The meta-analysis showed that compared with the mechanical mesh fixation group(MMFG), the glue mesh fixation group(GMFG) had significantly reduced incidences of chronic pain[relative risk (RR) = 0.40, 95% confidence interval (CI) (0.28,0.57), P < 0.00001], urinary retention[RR = 0.53, 95% CI(0.29,0.97), P = 0.04], haematoma[RR = 0.23, 95% CI(0.09,0.58), P = 0.002] and total complications[RR = 0.28, 95% CI(0.18,0.44), P < 0.00001]; there were no significant differences in pain score on postoperative day 1[MD = -1.33, 95% CI(-2.93,0.26), P = 0.10], operation time[MD = 1.46, 95% CI(-3.97,6.88), P = 0.60] and recurrence rate[RR = 0.72, 95% CI(0.35,1.47), P = 0.37] between the two groups. In conclusion, the application of glue mesh fixation in laparoscopic inguinal hernia repair is safe and reliable with fewer complications. Moreover, it can reduce the incidence of chronic pain without increasing the recurrence rate. However, due to the small number of cases in this analysis and limitations in the quality of the included studies, the findings need to be further verified by multicentre, large-sample and high-quality RCTs in the future.

Efficacy and Safety of Preoperative Radiotherapy Versus Chemoradiotherapy in Advanced Rectal Cancer: A Meta-analysis of Randomized Controlled Trials.

OBJECTIVE: This meta-analysis was conducted to evaluate the safety and efficacy of preoperative radiotherapy (RT) combined with surgery and preoperative chemoradiotherapy (CRT) combined with surgery for locally advanced rectal cancer. METHODS: PubMed, EMBASE and Cochrane Library were searched to collect published randomized controlled trials of preoperative radiotherapy or preoperative CRT combined with surgery for the treatment of locally advanced rectal cancer. Studies were screened according to inclusion and exclusion criteria, and quality was evaluated; RevMan 5.3 software was used for meta-analysis. RESULTS: In total, 7 related studies involving 3100 patients with locally advanced rectal cancer were evaluated. The pathological complete response rate, negative lymph node rate, R0 resection rate, and incidence of grade III/IV adverse reactions were lower in the RT group than in the CRT group. In the absence of postoperative chemotherapy, the 5-year local recurrence rate of RT was higher than that of CRT, but there was no significant difference between the groups among those who underwent postoperative chemotherapy. Moreover, there was no significant difference between the groups with regard to the 5-year survival rate, anal-preserving rate, or incidence of anastomotic leakage. CONCLUSION: Preoperative CRT is better than preoperative RT for the treatment of advanced rectal cancer, though the adverse reaction rate is higher.

The role of prophylactic antibiotics in elective inguinal tension-free hernia repair: A systematic review and meta-analysis.

Whether to use antibiotics to prevent surgical site infection in elective inguinal tension-free hernia repair has been controversial. To systematically evaluate the effect of prophylactic antibiotic application in elective inguinal tension-free hernia repair, we identified all published randomised controlled trials of the effect of prophylactic antibiotic application on elective inguinal tension-free hernia repair were collected by computer retrieval from the China National Knowledge Infrastructure; VIP Database; Wanfang Database; China Biomedical Literature Database; and PubMed, EMBASE and Cochrane Library databases. Meta-analysis was performed by RevMan 5.3 software. The meta-analysis showed that the total incidence of surgical site infections [P = 0.003] and the incidence of superficial surgical site infections [P = 0.004] in the antibiotic group (AG) were lower than those in the non-antibiotic group (NAG). There was no significant difference in the total incidence of postoperative infections [P = 0.06], deep surgical site infections [P = 0.26] and seroma [P = 0.52] between the AG and the NAG. Based on current evidence, the application of prophylactic antibiotics in elective inguinal tension-free hernia repair can prevent the total incidence of surgical site infections and that of superficial surgical site infections but cannot prevent the total incidence of postoperative infection events, incidence of deep surgical site infections and incidence of seroma.

Multivalent Ion-Modulated Electron Transfer Processes in Carbon Nanopipettes.

Conductive nanopipettes with both an electroactive interface and a pipet geometry have been recognized as powerful multifunctional probes in various electrochemical sensing and imaging applications. As confined inside the nanopipette, the excess surface charges at the solid/solution interface would then play a dominant role in the resulting charge transport processes. Herein, the effects of a multivalent ion on the resulting electron transfer (ET) processes in the carbon nanopipettes are investigated with both experimental and simulation methods. The multivalent cations (i.e., Ca2+, Mg2+, Co2+, and Ni2+) are shown to strongly adsorb at the negatively charged carbon surface and attract more Fe(CN)64- ions inside the cavity, as indicated by the increasing ET current responses. In addition to elucidating the fundamental charge transport processes in conductive nanopipettes to afford better usage as electrochemical probes, these results could also help in the development of new sensing methods for measuring the non-electroactive ions in biological or environmental systems.

Electrodeposition of Metal Nanoparticles inside Carbon Nanopipettes for Sensing Applications.

Conductive nanopipettes offer promising confined spaces to enable advanced electrochemical sensing applications in small spaces. Herein, a series of metal-decorated carbon nanopipettes (CNPs) were developed, in which Au, Ag, and Pt are modified at the inner walls of CNPs by a simple electrodeposition method. The fabricated tips show good sensing performances for a variety of important analytes, such as glucose, hydrogen peroxide, and chloride and hydrogen ions in biological and catalytic systems. This simple and effective approach can be further extended to prepare other functionalized nanopipette electrodes toward more versatile and powerful measurements in electrochemical sensing and imaging applications.