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Wachta I, Balasubramanian K. Electroanalytical Strategies for Local pH Sensing at Solid-Liquid Interfaces and Biointerfaces. ACS Sens 2024. [PMID: 39231377 DOI: 10.1021/acssensors.4c01391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2024]
Abstract
Obtaining analytical information about chemical species at interfaces is fundamentally important to improving our understanding of chemical reactions and biological processes. pH at solid-liquid interfaces is found to deviate from the bulk solution value, for example, in electrocatalytic reactions at surfaces or during the corrosion of metals. Also, in the vicinity of living cells, metabolic reactions or cellular responses cause changes in pH at the extracellular interface. In this review, we collect recent progress in the development of sensors with the capability to detect pH at or close to solid-liquid and bio interfaces, with spatial and time resolution. After the two main principles of pH detection are presented, the different classes of molecules and materials that are used as active components in these sensors are described. The review then focuses on the reported electroanalytical techniques for local pH sensing. As application examples, we discuss model studies that exploit local pH sensing in the area of electrocatalysis, corrosion, and cellular interfaces. We conclude with a discussion of key challenges for wider use of this analytical approach, which shows promise to improve the mechanistic understanding of reactions and processes at realistic interfaces.
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Affiliation(s)
- Isabell Wachta
- Department of Chemistry and School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, 10099 Berlin, Germany
| | - Kannan Balasubramanian
- Department of Chemistry and School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, 10099 Berlin, Germany
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2
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Wei D, Lv S, Zuo J, Liang S, Wang J, He T, Liu L. Fabrication of chitosan-based fluorescent hydrogel membranes cross-linked with bisbenzaldehyde for efficient selective detection and adsorption of Fe 2. Int J Biol Macromol 2024; 270:132088. [PMID: 38723821 DOI: 10.1016/j.ijbiomac.2024.132088] [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: 01/23/2024] [Revised: 03/29/2024] [Accepted: 05/02/2024] [Indexed: 05/20/2024]
Abstract
Chitosan, as a natural biomass material, is green, recyclable, sustainable and well biocompatible. The molecular chain is rich in active groups such as amino and hydroxyl groups, and its preparation of fluorescent probes has the advantages of biocompatibility and efficient detection performance. In this study, a bis(benzaldehyde) (BHD) fluorescent functional molecule was designed. Then a series of fluorescent chitosan-based hydrogel films (CSBHD) were prepared using chitosan as raw material and BHD as cross-linking agent. As a fluorescent probe for metal ions, CSBHD was able to efficiently detect Fe2+ with a linear correlation of fluorescence intensity in the range of 0-160 μM, and the limit of detection (LOD) was 0.55 μM. Moreover, it has excellent adsorption performance for Fe2+ ions, with a maximum adsorption capacity of 223.5 g/mg at 500 mg/L Fe2+ concentration. Finally, we characterised the structure and microscopic morphology of CSBHD films and found that CSBHD as a hydrogel film has a high cross-linking density, good water resistance, excellent thermal stability, strong resistance to swelling, and excellent stability in cycling tests. Hence, it has great potential for application in adsorption and detection of Fe2+ ions. It also provides a good strategy for the application of chitosan based fluorescent probe materials in environmental monitoring and heavy metal ion adsorption.
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Affiliation(s)
- Dequan Wei
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Shenghua Lv
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
| | - Jingjing Zuo
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Shan Liang
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Jialin Wang
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Tingxiang He
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Leipeng Liu
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
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Makogon A, Noël JM, Kanoufi F, Shkirskiy V. Deciphering the Interplay between Local and Global Dynamics of Anodic Metal Oxidation. Anal Chem 2024; 96:1129-1137. [PMID: 38197168 DOI: 10.1021/acs.analchem.3c04160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
The stark difference between global and local metal oxidation dynamics underscores the need for methodologies capable of performing precise sub-μm-scale and wide-field measurements. In this study, we present reflective microscopy as a tool developed to address this challenge, illustrated by the example of chronoamperometric Fe oxidation in a NaCl solution. Analysis at a local scale of 10 s of μm has revealed three distinct periods of Fe oxidation: the initial covering of the metal interface with a surface film, followed by the electrochemical conversion of the formed surface film, and finally, the in-depth oxidation of Fe. In addition, thermodynamic calculations and the quantitative analysis of changes in optical signal (light intensity), correlated with variations in refractive indexes, suggest the initial formation of maghemite, followed by its subsequent conversion to magnetite. The reactivity maps for all three periods are heterogeneous, which can be attributed to the preferential oxidation of certain crystallographic grains. Notably, at the global scale of 100 s of μm, reactivity initiates at the electrode border and progresses toward its center, demonstrating a unique pattern that is independent of the local metal structure. This finding underscores the significance of simultaneously employing sub-μm-precise, quantitative, and wide-field measurements for a comprehensive description of metal oxidation processes.
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Affiliation(s)
| | - Jean-Marc Noël
- ITODYS, CNRS, Université Paris Cité, 75013 Paris, France
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4
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Carbon dots-based fluorescence sensor for two-photon imaging of pH in diabetic mice. Front Chem Sci Eng 2022. [DOI: 10.1007/s11705-022-2212-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Al-Jeda M, Mena-Morcillo E, Chen A. Micro-Sized pH Sensors Based on Scanning Electrochemical Probe Microscopy. MICROMACHINES 2022; 13:2143. [PMID: 36557442 PMCID: PMC9785626 DOI: 10.3390/mi13122143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
Monitoring pH changes at the micro/nano scale is essential to gain a fundamental understanding of surface processes. Detection of local pH changes at the electrode/electrolyte interface can be achieved through the use of micro-/nano-sized pH sensors. When combined with scanning electrochemical microscopy (SECM), these sensors can provide measurements with high spatial resolution. This article reviews the state-of-the-art design and fabrication of micro-/nano-sized pH sensors, as well as their applications based on SECM. Considerations for selecting sensing probes for use in biological studies, corrosion science, in energy applications, and for environmental research are examined. Different types of pH sensitive probes are summarized and compared. Finally, future trends and emerging applications of micro-/nano-sized pH sensors are discussed.
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Affiliation(s)
| | | | - Aicheng Chen
- Correspondence: ; Tel.: +1-519-824-4120 (ext. 54764)
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A camphor-based Schiff base fluorescent probe for detection of alkaline pH and its applications in living cells. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2021.132038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Monteiro MO, Mirabal A, Jacobse L, Doblhoff-Dier K, Barton SC, Koper MTM. Time-Resolved Local pH Measurements during CO 2 Reduction Using Scanning Electrochemical Microscopy: Buffering and Tip Effects. JACS AU 2021; 1:1915-1924. [PMID: 34849509 PMCID: PMC8611793 DOI: 10.1021/jacsau.1c00289] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Indexed: 06/13/2023]
Abstract
The electrochemical reduction of CO2 is widely studied as a sustainable alternative for the production of fuels and chemicals. The electrolyte's bulk pH and composition play an important role in the reaction activity and selectivity and can affect the extent of the buildup of pH gradients between the electrode surface and the bulk of the electrolyte. Quantifying the local pH and how it is affected by the solution species is desirable to gain a better understanding of the CO2 reduction reaction. Local pH measurements can be realized using Scanning Electrochemical Microscopy (SECM); however, finding a pH probe that is stable and selective under CO2 reduction reaction conditions is challenging. Here, we have used our recently developed voltammetric pH sensor to perform pH measurements in the diffusion layer during CO2 reduction using SECM, with high time resolution. Using a 4-hydroxylaminothiophenol (4-HATP)/4-nitrosothiophenol (4-NSTP) functionalized gold ultramicroelectrode, we compare the local pH developed above a gold substrate in an argon atmosphere, when only hydrogen evolution is taking place, to the pH developed in a CO2 atmosphere. The pH is monitored at a fixed distance from the surface, and the sample potential is varied in time. In argon, we observe a gradual increase of pH, while a plateau region is present in CO2 atmosphere due to the formation of HCO3 - buffering the reaction interface. By analyzing the diffusion layer dynamics once the sample reaction is turned "off", we gain insightful information on the time scale of the homogeneous reactions happening in solution and on the time required for the diffusion layer to fully recover to the initial bulk concentration of species. In order to account for the effect of the presence of the SECM tip on the measured pH, we performed finite element method simulations of the fluid and reaction dynamics. The results show the significant localized diffusion hindrance caused by the tip, so that in its absence, the pH values are more acidic than when the tip is present. Nonetheless, through the simulation, we can account for this effect and estimate the real local pH values across the diffusion layer.
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Affiliation(s)
- Mariana
C. O. Monteiro
- Leiden
Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Alex Mirabal
- Department
of Chemical & Materials Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Leon Jacobse
- Centre
for X-ray and Nano Science CXNS, Deutsches
Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany
| | - Katharina Doblhoff-Dier
- Leiden
Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Scott Calabrese Barton
- Department
of Chemical & Materials Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Marc T. M. Koper
- Leiden
Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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A simulation and experimental study of electrochemical pH control at gold interdigitated electrode arrays. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.139113] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Bollella P, Melman A, Katz E. Electrochemically Generated Interfacial pH Change: Application to Signal‐Triggered Molecule Release. ChemElectroChem 2020. [DOI: 10.1002/celc.202000615] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Paolo Bollella
- Department of Chemistry and Biomolecular ScienceClarkson University 8 Clarkson Ave. Potsdam NY 13699 USA
| | - Artem Melman
- Department of Chemistry and Biomolecular ScienceClarkson University 8 Clarkson Ave. Potsdam NY 13699 USA
| | - Evgeny Katz
- Department of Chemistry and Biomolecular ScienceClarkson University 8 Clarkson Ave. Potsdam NY 13699 USA
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11
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Monteiro MCO, Jacobse L, Touzalin T, Koper MTM. Mediator-Free SECM for Probing the Diffusion Layer pH with Functionalized Gold Ultramicroelectrodes. Anal Chem 2020; 92:2237-2243. [PMID: 31874560 PMCID: PMC6977089 DOI: 10.1021/acs.analchem.9b04952] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
Probing
pH gradients during electrochemical reactions is important
to better understand reaction mechanisms and to separate the influence
of pH and pH gradients from intrinsic electrolyte effects. Here, we
develop a pH sensor to measure pH changes in the diffusion layer during
hydrogen evolution. The probe was synthesized by functionalizing a
gold ultramicroelectrode with a self-assembled monolayer of 4-nitrothiophenol
(4-NTP) and further converting it to form a hydroxylaminothiophenol
(4-HATP)/4-nitrosothiophenol (4-NSTP) redox couple. The pH sensing
is realized by recording the tip cyclic voltammetry and monitoring
the Nernstian shift of the midpeak potential. We employ a capacitive
approach technique in our home-built Scanning Electrochemical Microscope
(SECM) setup in which an AC potential is applied to the sample and
the capacitive current generated at the tip is recorded as a function
of distance. This method allows for an approach of the tip to the
electrode that is electrolyte-free and consequently also mediator-free.
Hydrogen evolution on gold in a neutral electrolyte was studied as
a model system. The pH was measured with the probe at a constant distance
from the electrode (ca. 75 μm), while the electrode potential
was varied in time. In the nonbuffered electrolyte used (0.1 M Li2SO4), even at relatively low current densities,
a pH difference of three units is measured between the location of
the probe and the bulk electrolyte. The time scale of the diffusion
layer transient is captured, due to the high time resolution that
can be achieved with this probe. The sensor has high sensitivity,
measuring differences of more than 8 pH units with a resolution better
than 0.1 pH unit.
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Affiliation(s)
- Mariana C O Monteiro
- Leiden Institute of Chemistry , Leiden University , P.O. Box 9502, 2300 RA , Leiden , The Netherlands
| | - Leon Jacobse
- DESY NanoLab , Deutsches Elektronensynchrotron DESY , Notkestrasse 85 , D-22607 Hamburg , Germany
| | - Thomas Touzalin
- Leiden Institute of Chemistry , Leiden University , P.O. Box 9502, 2300 RA , Leiden , The Netherlands
| | - Marc T M Koper
- Leiden Institute of Chemistry , Leiden University , P.O. Box 9502, 2300 RA , Leiden , The Netherlands
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