1
|
Tubbs A, Ahmed JU, Christopher J, Alvarez JC. Savitzky-Golay processing and bidimensional plotting of current-time signals from stochastic blocking electrochemistry to analyze mixtures of rod-shaped bacteria. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2024; 16:6570-6576. [PMID: 39234687 DOI: 10.1039/d4ay00899e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/06/2024]
Abstract
In stochastic blocking electrochemistry, adsorptive collisions of nano and micro-particles with an ultramicroelectrode (UME) generate steps of decreasing current overlaid on the current-time (i-t) baseline of an electroactive mediator reacting at the UME. The step amplitude (Δi) induced by particle blockage informs about its size, while collision frequency correlates with particle transport. However, because most particles arrive at the UME faster than the acquisition speed of conventional electrochemical instruments, current steps appear vertical. Recently, when analyzing rod-shape bacteria (bacilli), we detected slanted steps of duration Δt (∼0.6 to 1.1 s) that were found to scale up with bacillus length (∼1 to 5 μm, respectively). In this work, we apply a Savitzky-Golay (SG) algorithm coded in MATLAB to convert experimental i-t recordings into derivative plots of Δi/Δt versus t. As a result, current steps become peaks on a flat baseline. Unlike the original values of Δi and Δt that require manual gauging, the coded SG-algorithm generates both parameters automatically from peak integration. We then display Δi and Δt in bidimensional scatter plots comparing mixtures of A. erythreum (∼1 μm) and B. subtilis (∼5 μm). The spread of Δi and Δt values complies with the size distribution observed using scanning electron microscopy. By introducing SG-processing and bidimensional plotting of i-t recordings from stochastic blocking data we broaden the scope of the technique. The approach facilitates distinguishing bacilli in mixtures because both Δt and Δi increase with bacillus length and now they can be displayed in a single graph along with adsorption frequency. Moreover, density distribution and proportion of data points from groups of bacteria are also discernible from the plots.
Collapse
Affiliation(s)
- Ashley Tubbs
- Chemistry Department, Virginia Commonwealth University, Richmond, VA, 23284, USA.
| | - Junaid U Ahmed
- Chemistry Department, Khulna University of Engineering and Technology, Bangladesh
| | - Jayani Christopher
- Chemistry Department, Virginia Commonwealth University, Richmond, VA, 23284, USA.
| | - Julio C Alvarez
- Chemistry Department, Virginia Commonwealth University, Richmond, VA, 23284, USA.
| |
Collapse
|
2
|
Lutkenhaus JA, Ahmed JU, Hasan M, Prosser DC, Alvarez JC. Average collision velocity of single yeast cells during electrochemically induced impacts. Analyst 2024; 149:3214-3223. [PMID: 38656271 DOI: 10.1039/d4an00134f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
We recorded current-time (i-t) profiles for oxidizing ferrocyanide (FCN) while spherical yeast cells of radius (rc ≈ 2 μm) collided with disk ultramicroelectrodes (UMEs) of increasing radius (re ≈ 12-45 μm). Collision signals appear as minority steps and majority blips of decreased current overlayed on the i-t baseline when cells block ferrocyanide flux (JFCN). We assigned steps to adsorption events and blips to bouncing collisions or contactless passages. Yeast cells exhibit impact signals of long duration (Δt ≈ 15-40 s) likely due to sedimentation. We assume cells travel a threshold distance (T) to generate collision signals of duration Δt. Thus, T represents a distance from the UME surface, at which cell perturbations on JFCN blend in with the UME noise level. To determine T, we simulated the UME current, while placing the cell at increasing distal points from the UME surface until matching the bare UME current. T-Values at 90°, 45°, and 0° from the UME edge and normal to the center were determined to map out T-regions in different experimental conditions. We estimated average collision velocities using the formula T/Δt, and mimicked cells entering and leaving T-regions at the same angle. Despite such oversimplification, our analysis yields average velocities compatible with rigorous transport models and matches experimental current steps and blips. We propose that single-cells encode collision dynamics into i-t signals only when cells move inside the sensitive T-region, because outside, perturbations of JFCN fall within the noise level set by JFCN and rc/re (experimentally established). If true, this notion will enable selecting conditions to maximize sensitivity in stochastic blocking electrochemistry. We also exploited the long Δt recorded here for yeast cells, which was undetectable for the fast microbeads used in early pioneering work. Because Δt depends on transport, it provides another analytical parameter besides current for characterizing slow-moving cells like yeast.
Collapse
Affiliation(s)
- John A Lutkenhaus
- Chemistry Department, Virginia Commonwealth University, Richmond, VA, 23294, USA.
| | - Junaid U Ahmed
- Chemistry Department, Khulna University of Engineering and Technology, Bangladesh
| | - Mehedi Hasan
- Chemistry Department, Virginia Commonwealth University, Richmond, VA, 23294, USA.
| | - Derek C Prosser
- Biology Department, Virginia Commonwealth University, Richmond, VA, 23294, USA
| | - Julio C Alvarez
- Chemistry Department, Virginia Commonwealth University, Richmond, VA, 23294, USA.
| |
Collapse
|
3
|
Du M, Zhang L, Meng Y, Chen J, Liu F. Impact of Surface Chemistry on Emulsion-Electrode Interactions and Electron-Transfer Kinetics in the Single-Entity Electrochemistry. Anal Chem 2024; 96:1038-1045. [PMID: 38181449 DOI: 10.1021/acs.analchem.3c03462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2024]
Abstract
Single-entity electrochemistry (SEE) provides powerful means to track a single particle, single cell, and even single molecule from the nano to microscale. The electrode serves as not only the detector of collision but also the surface supplier in SEE, and the fundamental understanding of the electrode surface chemistry on the dynamic particle-electrode interactions and electrochemical responses of a single particle still remains unexplored, particularly for soft particles. Herein, dynamic interactions of microemulsions and the interaction-controlled electron-transfer (ET) kinetics are studied employing SEE and fluorescence spectroscopy. The o/w-type nitrobenzene emulsions were prepared with the surfactant-type room temperature ionic liquids (RTILs). Biased the electrode potential for the reduction of 7,7,8,8-tetracyanoquinodimethane within emulsions, it is surprising to see the distinct collision current signals on the carbon fiber ultramicroelectrode (C UME) and Au ultramicroelectrode (Au UME) in the late stage of chronoamperometric measurements. Theoretical understanding was made to determine the ET kinetics behind the disparate current signals. It is believed that the electrode surface chemistry, i.e., the surface energy, has a great influence on the dynamic emulsion-electrode interactions and ET kinetics. On the hydrophilic surface of Au UME, emulsions tend to decompose/detach from the electrode surface immediately after colliding. In contrast, on the lipophilic surface of C UME with lower surface energy, a layer of oil phase accumulated by the coalescence of emulsions and the migration of the precedent colliding emulsions, which would serve as a barrier to block ET via tunneling as manifested by the gradual slowdown of ET rate and the reduced collision frequency in the late stage of measurement. The impacts of the emulsion size and amphiphilicity of RTILs on the C UME-emulsion interactions and ET kinetics were also investigated.
Collapse
Affiliation(s)
- Minshu Du
- School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, China
| | - Lizhu Zhang
- School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, China
| | - Yao Meng
- Shaanxi Huaqin New Energy Technology Co., Ltd, Xi'an, Shaanxi 710119, China
| | - Jiajia Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Feng Liu
- School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, China
| |
Collapse
|
4
|
Zhang H, Gao G, Chen Y, Lin L, Wang D, Fan Y, Liu Y, Zhao Q, Zhi J. Effect of cell settlement on the electrochemical collision behaviors of single microbes. Anal Chim Acta 2023; 1283:341949. [PMID: 37977779 DOI: 10.1016/j.aca.2023.341949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/16/2023] [Accepted: 10/20/2023] [Indexed: 11/19/2023]
Abstract
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.
Collapse
Affiliation(s)
- Hanxin Zhang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Guanyue Gao
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
| | - Yafei Chen
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Lan Lin
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Dengchao Wang
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Yining Fan
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Yanran Liu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Qi Zhao
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Jinfang Zhi
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
| |
Collapse
|
5
|
Vannoy KJ, Renault C, Dick JE. The Microelectrode Insulator Influences Water Nanodroplet Collisions. Anal Chem 2023; 95:7286-7293. [PMID: 37092981 DOI: 10.1021/acs.analchem.3c00287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Studying chemical reactions in very small (attoliter to picoliter) volumes is important in understanding how chemistry proceeds at all relevant scales. Stochastic electrochemistry is a powerful tool to study the dynamics of single nanodroplets, one at a time. Perhaps the most conceptually simple experiment is that of the current blockade, where the collision of an insulating particle is observed electrochemically as a stepwise decrease in current. Here, we demonstrate that nanodroplet collisions on microelectrodes are not as simple as water droplets adsorbing to the electrode to block current and that the environment immediately around the microelectrode (glass insulator) plays a pivotal role in the electrochemical collision response. We use correlated opto-electrochemical measurements to understand a variety of electrochemical responses when water nanodroplets collide with a microelectrode during the heterogeneous oxidation of decamethylferrocene in oil. The amperometric current reports not only on current blockades but also on nanodroplet coalescence events and preferential wetting to the glass around the microelectrode. Treating the glass with dichlorodimethylsilane creates a hydrophobic environment around the working electrode, and the simple current blockade response expected from the absorption of insolating nanoparticles is observed. These results highlight the importance of the environment around the working electrode for nanodroplet collision studies.
Collapse
Affiliation(s)
- Kathryn J Vannoy
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Christophe Renault
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jeffrey E Dick
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
- Elmore Family School of Electrical and Computer Engineering, West Lafayette, Indiana 47907, United States
| |
Collapse
|
6
|
Ahmed JU, Lutkenhaus JA, Tubbs A, Nag A, Christopher J, Alvarez JC. Estimating Average Velocities of Particle Arrival Using the Time Duration of the Current Signal in Stochastic Blocking Electrochemistry. Anal Chem 2022; 94:16560-16569. [DOI: 10.1021/acs.analchem.2c01201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Junaid U. Ahmed
- Chemistry Department, Virginia Commonwealth University, Richmond, Virginia23284, United States
| | - John A. Lutkenhaus
- Chemistry Department, Virginia Commonwealth University, Richmond, Virginia23284, United States
| | - Ashley Tubbs
- Chemistry Department, Virginia Commonwealth University, Richmond, Virginia23284, United States
| | - Ashish Nag
- Chemistry Department, Virginia Commonwealth University, Richmond, Virginia23284, United States
| | - Jayani Christopher
- Chemistry Department, Virginia Commonwealth University, Richmond, Virginia23284, United States
| | - Julio C. Alvarez
- Chemistry Department, Virginia Commonwealth University, Richmond, Virginia23284, United States
| |
Collapse
|
7
|
Hafez ME, Mohammed ATA. Revealing the Catalytic Activities of Single-Dispersed Pd Clusters Embedded on Hollow Nanoparticles toward the Hydrogen Evolution Reaction. ACS APPLIED MATERIALS & INTERFACES 2022; 14:43290-43297. [PMID: 36099560 DOI: 10.1021/acsami.2c11624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Hydrogen evolution reaction (HER) is one of the revolutionary aspects that grab lots of attention for the production of clean energy sources, increasing the demands of revealing the intrinsic activities of HER catalysts for designing efficient candidates. Based on using only surface active sites on solid nanoparticles (SNPs), catalysts with high atom dispersion are immensely desirable to magnify their efficiency through maximum atom utilization. Herein, we employed hollow mesoporous silica nanoparticles (HMSNPs) as an insulating nanoplatform for engineering single-dispersed Pd clusters on their surface, assuring high dispersion of the Pd clusters. We then tracked their intrinsic activities using stochastic nanocollision electrochemistry (SNCEC). The insulating silica nanoplatform helped investigate the single-dispersed Pd clusters per contact point of Pd@HMSNP at the electrode surface, revealing exceptional HER performance with high maximum turnover numbers and low onset potential for initiating the HER compared to those of SNPs. Using insulating silica allowed electron transfer only from the single-dispersed Pd cluster at the contact point of Pd@HMSNP to the electrode. Moreover, the high-temporal measurement of SNCEC revealed the diversity of spike shapes based on the heterogeneity of the contact point of Pd@HMSNP, ensuring the capability of the single-entity measurements to distinguish the structure relationship behaviors of the single-dispersed Pd cluster at the electrode/solution interface and clearly clarifying the electron transfer process with complementary information. This work provides sufficient evidence for the importance of atom dispersions in designing highly efficient HER Pd catalysts.
Collapse
Affiliation(s)
- Mahmoud Elsayed Hafez
- Key Laboratory for Advanced Materials, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology & Dynamic Chemistry, School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
- Department of Chemistry, Faculty of Science, Beni-Suef University, Beni-Suef 62511, Egypt
| | - Abdulelah T A Mohammed
- Key Laboratory of Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234, P. R. China
| |
Collapse
|
8
|
Qiu X, Tang H, Dong J, Wang C, Li Y. Stochastic Collision Electrochemistry from Single Pt Nanoparticles: Electrocatalytic Amplification and MicroRNA Sensing. Anal Chem 2022; 94:8202-8208. [PMID: 35642339 DOI: 10.1021/acs.analchem.2c00116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Single-particle collisions have made many achievements in basic research, but challenges still exist due to their low collision frequency and selectivity in complex samples. In this work, we developed an "on-off-on" strategy based on Pt nanoparticles (PtNPs) that catalyze N2H4 collision signals on the surface of carbon ultramicroelectrodes and established a new method for the detection of miRNA21 with high selectivity and sensitivity. PtNPs catalyze the reduction of N2H4 on the surface of carbon ultramicroelectrodes to generate a stepped collision signal, which is in the "on" state. The single-stranded DNA paired with miRNA21 is coupled with PtNPs to form the complex DNA/PtNPs. Because PtNPs are covered by DNA, the electrocatalytic collision of N2H4 oxidation is inhibited. At this time, the signal is in the "off" state. When miRNA21 is added, the strong complementary pairing between miRNA21 and DNA destroys the electrostatic adsorption of DNA/PtNP conjugates and restores the electrocatalytic performance of PtNPs, and the signal is in the "on" state again. Based on this, a new method for detecting miRNA21 was established. It provides a new way for small-molecule sensing and has a wide range of applications in electroanalysis, electrocatalysis, and biosensing.
Collapse
Affiliation(s)
- Xia Qiu
- Anhui Key Laboratory of Chemo/Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, P.R. China
| | - Haoran Tang
- Anhui Key Laboratory of Chemo/Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, P.R. China
| | - Jingyi Dong
- Anhui Key Laboratory of Chemo/Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, P.R. China
| | - Chaohui Wang
- Anhui Key Laboratory of Chemo/Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, P.R. China
| | - Yongxin Li
- Anhui Key Laboratory of Chemo/Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, P.R. China
| |
Collapse
|