Electrochemical sensing at nanoporous film‐coated electrodes

Ito, Takashi; Nathani, Akash

doi:10.1002/elsa.202100126

Cited by 5 publications

(5 citation statements)

References 90 publications

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“…The observation of a steady-state voltammetric response for Ru(NH 3 ) 6 3+ reduction, following the partial removal of the La(OH) 3 film by scanning to positive potentials, was surprising as La(OH) 3 is reported to be an electronically insulating material . There are several possible mechanisms that may be responsible for this phenomenon, namely, (i) there are pinholes in the films through which Ru(NH 3 ) 6 3+ is diffusing; − (ii) La(OH) 3 is ionically conducting and Ru(NH 3 ) 6 3+ is transported through the film; − or (iii) the film is sufficiently thin to allow electron tunneling between the underlying Pt electrode surface and redox molecule. − To explore these mechanisms, we performed steady-state voltammetric experiments using three additional outer-sphere redox species: the neutral ferrocene methanol (FcMeOH) and negatively charged ferrocyanide and ferricyanide.…”

Section: Resultsmentioning

confidence: 99%

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

2022

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We report investigations of the deposition of nanometer-thick Ln(OH) 3 films (Ln = La, Ce, and Lu) and their effect on outer-sphere and inner-sphere electron-transfer reactions. Insoluble Ln(OH) 3 films are deposited from aqueous solutions of LaCl 3 onto the surface of 12.5 μm radius Pt microdisk electrodes during water or oxygen reduction. Both reactions produce interfacial OH − , which complexes with Ln 3+ , resulting in the precipitation of Ln(OH) 3 . Surface analyses by scanning electron microscopy (SEM), SEM−energy-dispersive X-ray spectroscopy, and atomic force microscopy indicate the formation of a 1−2 nm thick uniform film. Outer-sphere electron-transfer reactions (Ru-(NH 3 ) 6 3+ reduction, FcMeOH oxidation, and Fe(CN) 6 4−/3− oxidation/reduction) were investigated at Ln(OH) 3 -modified electrodes of different film thicknesses. The results demonstrate that the steady-state transport-limited current for these reactions decreases with an increase in the film thickness. Moreover, the degree of blockage depends upon the redox species, suggesting that the Ln(OH) 3 films are free from pinholes greater than the size of the redox molecules. This suggests that the films are either ionically conducting or that electron tunneling occurs across these thin layers. A similar blocking effect was observed for the inner-sphere reductions of H 2 O and O 2 . We further demonstrate that the thickness of La(OH) 3 films can be controlled by anodic dissolution. Additionally, we show that La 3+ lowers the supersaturation of dissolved H 2 required to nucleate a stable nanobubble.

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Section: Resultsmentioning

confidence: 99%

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

2022

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“…pH-dependent ionic nanopore transport through mesoporous silica films is a promising technology for various applications such as sensing, desalination, and energy conversion. ,− Here, ionic nanopore transport at changing bulk pH was studied by cyclic voltammetry to understand the role of PDA presence and amount at the nanoporous and mesoporous film surface. Cyclic voltammetry measurements were performed when the PDA-functionalized mesoporous films were in contact with an aqueous electrolyte solution, containing anionic ([Fe(CN) 6 ] 3–/4– ) (Figures and a–c) or cationic ([Ru(NH 3 ) 6 ] 2+/3+ ) (Figures and d–f) redox probes.…”

Section: Resultsmentioning

confidence: 99%

“…The performance of the biological ion channels and pores is the key to survival for many living species. , Their precise mass transport control inspired scientists to build novel porous materials for challenging applications such as water purification, − energy conversion, − and molecular sensing. , One promising technology for mimicking these biological nanogates is ceramic mesoporous films functionalized by stimuli-responsive synthetic units at their pore sites. Mesoporous silica films have received significant attention among solid-state nanoporous films, thanks to their facile fabrication method and silanol-rich surface groups, making them easily adaptable for various chemical functionalization techniques.…”

Section: Introductionmentioning

confidence: 99%

Electropolymerization of Polydopamine at Electrode-Supported Insulating Mesoporous Films

Varol,

Herberger,

Kirsch

et al. 2023

Chem. Mater.

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Bioinspired, stimuli-responsive, polymer-functionalized mesoporous films are promising platforms for precisely regulating nanopore transport toward applications in water management, iontronics, catalysis, sensing, drug delivery, or energy conversion. Nanopore technologies still require new, facile, and effective nanopore functionalization with multi- and stimuli-responsive polymers to reach these complicated application targets. In recent years, zwitterionic and multifunctional polydopamine (PDA) films deposited on planar surfaces by electropolymerization have helped surfaces respond to various external stimuli such as light, temperature, moisture, and pH. However, PDA has not been used to functionalize nanoporous films, where the PDA-coating could locally regulate the ionic nanopore transport. This study investigates the electropolymerization of homogeneous thin PDA films to functionalize nanopores of mesoporous silica films. We investigate the effect of different mesoporous film structures and the number of electropolymerization cycles on the presence of PDA at mesopores and mesoporous film surfaces. Our spectroscopic, microscopic, and electrochemical analysis reveals that the amount and location (pores and surface) of deposited PDA at mesoporous films is related to the combination of the number of electropolymerization cycles and the mesoporous film thickness and pore size. In view of the application of the proposed PDA-functionalized mesoporous films in areas requiring ion transport control, we studied the ion nanopore transport of the films by cyclic voltammetry. We realized that the amount of PDA in the nanopores helps to limit the overall ionic transport, while the pH-dependent transport mechanism of pristine silica films remains unchanged. It was found that (i) the pH-dependent deprotonation of PDA and silica walls and (ii) the insulation of the indium-tin oxide (ITO) surface by increasing the amount of PDA within the mesoporous silica film affect the ionic nanopore transport.

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“…The uniform size (shape) of nanopores coating the surface of an electrode plays a significant role in separating specific analytes/antibodies and offering high affinity of the antigen through chemical or electrostatic interactions [ 128 ]. The redox-active moiety can be tailored on a pore’s endogenous surface for analyte preconcentration using electrostatic/steric interactions.…”

Section: Challenges In Electrochemical Sensingmentioning

confidence: 99%

Challenges and Advances in Biomarker Detection for Rapid and Accurate Sepsis Diagnosis: An Electrochemical Approach

Kumar,

Banaś,

Krukiewicz

2024

Biosensors

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Sepsis is a life-threatening condition with high mortality rates due to delayed treatment of patients. The conventional methodology for blood diagnosis takes several hours, which suspends treatment, limits early drug administration, and affects the patient’s recovery. Thus, rapid, accurate, bedside (onsite), economical, and reliable sepsis biomarker reading of the clinical sample is an emergent need for patient lifesaving. Electrochemical label-free biosensors are specific and rapid devices that are able to perform analysis at the patient’s bedside; thus, they are considered an attractive methodology in a clinical setting. To reveal their full diagnostic potential, electrode architecture strategies of fabrication are highly desirable, particularly those able to preserve specific antibody–antigen attraction, restrict non-specific adsorption, and exhibit high sensitivity with a low detection limit for a target biomarker. The aim of this review is to provide state-of-the-art methodologies allowing the fabrication of ultrasensitive and highly selective electrochemical sensors for sepsis biomarkers. This review focuses on different methods of label-free biomarker sensors and discusses their advantages and disadvantages. Then, it highlights effective ways of avoiding false results and the role of molecular labels and functionalization. Recent literature on electrode materials and antibody grafting strategies is discussed, and the most efficient methodology for overcoming the non-specific attraction issues is listed. Finally, we discuss the existing electrode architecture for specific biomarker readers and promising tactics for achieving quick and low detection limits for sepsis biomarkers.

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Electrochemical sensing at nanoporous film‐coated electrodes

Cited by 5 publications

References 90 publications

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Electropolymerization of Polydopamine at Electrode-Supported Insulating Mesoporous Films

Challenges and Advances in Biomarker Detection for Rapid and Accurate Sepsis Diagnosis: An Electrochemical Approach

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Electrochemical sensing at nanoporous film‐coated electrodes

Cited by 5 publications

References 90 publications

Electroprecipitation of Nanometer-Thick Films of Ln(OH)3 [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Electroprecipitation of Nanometer-Thick Films of Ln(OH)3 [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Electropolymerization of Polydopamine at Electrode-Supported Insulating Mesoporous Films

Challenges and Advances in Biomarker Detection for Rapid and Accurate Sepsis Diagnosis: An Electrochemical Approach

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Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions