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Hellmann A, Neusser G, Daboss S, Elnagar MM, Liessem J, Mitoraj D, Beranek R, Arbault S, Kranz C. Pt-Black-Modified (Hemi)spherical AFM Sensors: In Situ Imaging of Light-Driven Hydrogen Peroxide Evolution. Anal Chem 2024; 96:3308-3317. [PMID: 38354051 PMCID: PMC10902814 DOI: 10.1021/acs.analchem.3c03957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 01/28/2024] [Accepted: 02/01/2024] [Indexed: 02/28/2024]
Abstract
In this work, we present (hemi)spherical atomic force microscopy (AFM) sensors for the detection of hydrogen peroxide. Platinum-black (Pt-B) was electrodeposited onto conductive colloidal AFM probes or directly at recessed microelectrodes located at the end of a tipless cantilever, resulting in electrocatalytically active cantilever-based sensors that have a small geometric area but, due to the porosity of the films, exhibit a large electroactive surface area. Focused ion beam-scanning electron microscopy tomography revealed the porous 3D structure of the deposited Pt-B. Given the accurate positioning capability of AFM, these probes are suitable for local in situ sensing of hydrogen peroxide and at the same time can be used for (electrochemical) force spectroscopy measurements. Detection limits for hydrogen peroxide in the nanomolar range (LOD = 68 ± 7 nM) were obtained. Stability test and first in situ proof-of-principle experiments to achieve the electrochemical imaging of hydrogen peroxide generated at a microelectrode and at photocatalytically active structured poly(heptazine imide) films are demonstrated. Force spectroscopic data of the photocatalyst films were recorded in ambient conditions, in solution, and by applying a potential, which demonstrates the versatility of these novel Pt-B-modified spherical AFM probes.
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Affiliation(s)
- Andreas Hellmann
- Institute
of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Gregor Neusser
- Institute
of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Sven Daboss
- Institute
of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Mohamed M. Elnagar
- Institute
of Electrochemistry, Ulm University, Albert-Einstein-Allee 47, 89081 Ulm, Germany
| | - Johannes Liessem
- Institute
of Electrochemistry, Ulm University, Albert-Einstein-Allee 47, 89081 Ulm, Germany
| | - Dariusz Mitoraj
- Institute
of Electrochemistry, Ulm University, Albert-Einstein-Allee 47, 89081 Ulm, Germany
| | - Radim Beranek
- Institute
of Electrochemistry, Ulm University, Albert-Einstein-Allee 47, 89081 Ulm, Germany
| | - Stéphane Arbault
- Univ.
Bordeaux, CNRS, Bordeaux INP, UMR 5248, CBMN, F-33600 Pessac, France
| | - Christine Kranz
- Institute
of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
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Raßmann N, Weber M, Glaß REJ, Kreger K, Helfricht N, Schmidt HW, Papastavrou G. Electrogelation: Controlled Fast Formation of Micrometer-Thick Films from Low-Molecular Weight Hydrogelators. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:17190-17200. [PMID: 37976397 DOI: 10.1021/acs.langmuir.3c02270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
The controlled electrochemical deposition of hydrogels from low-molecular weight hydrogelators (LMWHGs) allows for the defined formation of thin films on electrodes. Here, the deposition of fibrillar networks consisting of N,N',N″-tris(4-carboxyphenylene)-1,3,5-benzenetricarboxamide (BTA) onto ultraflat gold electrodes has been studied. This process, also termed electrogelation, is based on a local change in the pH due to electrolysis of water at the electrode. The protonation of the BTA sodium salt leads to self-assembly into supramolecular fibrillar structures mainly via hydrogen bonding of the uncharged molecules. The resulting hydrogel film was characterized in terms of its thickness by atomic force microscopy (AFM). Two different AFM-based techniques have been used: ex situ imaging of dried films and in situ nanoindentation of the hydrated hydrogel films. The deposition process was studied as a function of gelator concentration, applied potential, and gelation time. These parameters allow control of the film thickness to a high degree of accuracy within a few tenths of nanometers. Film formation takes place in a few seconds at moderate applied potentials, which is beneficial for biomedical applications. The results obtained for the BTA presented here can be transferred to any type of pH-responsive LMWHG and many reversibly formed hydrogel films.
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Affiliation(s)
- Nadine Raßmann
- Department of Physical Chemistry II, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
| | - Melina Weber
- Department of Macromolecular Chemistry I, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
| | - Roman E J Glaß
- Department of Physical Chemistry II, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
| | - Klaus Kreger
- Department of Macromolecular Chemistry I, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
| | - Nicolas Helfricht
- Department of Physical Chemistry II, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
| | - Hans-Werner Schmidt
- Department of Macromolecular Chemistry I, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
- Bavarian Polymer Institute, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
| | - Georg Papastavrou
- Department of Physical Chemistry II, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
- Bavarian Polymer Institute, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
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Karg A, Gödrich S, Dennstedt P, Helfricht N, Retsch M, Papastavrou G. An Integrated, Exchangeable Three-Electrode Electrochemical Setup for AFM-Based Scanning Electrochemical Microscopy. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23115228. [PMID: 37299955 DOI: 10.3390/s23115228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 05/14/2023] [Accepted: 05/27/2023] [Indexed: 06/12/2023]
Abstract
Scanning electrochemical microscopy (SECM) is a versatile scanning probe technique that allows monitoring of a plethora of electrochemical reactions on a highly resolved local scale. SECM in combination with atomic force microscopy (AFM) is particularly well suited to acquire electrochemical data correlated to sample topography, elasticity, and adhesion, respectively. The resolution achievable in SECM depends critically on the properties of the probe acting as an electrochemical sensor, i.e., the working electrode, which is scanned over the sample. Hence, the development of SECM probes received much attention in recent years. However, for the operation and performance of SECM, the fluid cell and the three-electrode setup are also of paramount importance. These two aspects received much less attention so far. Here, we present a novel approach to the universal implementation of a three-electrode setup for SECM in practically any fluid cell. The integration of all three electrodes (working, counter, and reference) near the cantilever provides many advantages, such as the usage of conventional AFM fluid cells also for SECM or enables the measurement in liquid drops. Moreover, the other electrodes become easily exchangeable as they are combined with the cantilever substrate. Thereby, the handling is improved significantly. We demonstrated that high-resolution SECM, i.e., resolving features smaller than 250 nm in the electrochemical signal, could be achieved with the new setup and that the electrochemical performance was equivalent to the one obtained with macroscopic electrodes.
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Affiliation(s)
- Andreas Karg
- Physical Chemistry II, University of Bayreuth, 95447 Bayreuth, Germany
- Bavarian Institute for Battery Technology, University of Bayreuth, 95448 Bayreuth, Germany
| | - Sebastian Gödrich
- Physical Chemistry II, University of Bayreuth, 95447 Bayreuth, Germany
| | - Philipp Dennstedt
- Physical Chemistry II, University of Bayreuth, 95447 Bayreuth, Germany
- Bavarian Institute for Battery Technology, University of Bayreuth, 95448 Bayreuth, Germany
| | - Nicolas Helfricht
- Physical Chemistry II, University of Bayreuth, 95447 Bayreuth, Germany
| | - Markus Retsch
- Bavarian Institute for Battery Technology, University of Bayreuth, 95448 Bayreuth, Germany
- Physical Chemistry I, University of Bayreuth, 95447 Bayreuth, Germany
| | - Georg Papastavrou
- Physical Chemistry II, University of Bayreuth, 95447 Bayreuth, Germany
- Bavarian Institute for Battery Technology, University of Bayreuth, 95448 Bayreuth, Germany
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Karg A, Kuznetsov V, Helfricht N, Lippitz M, Papastavrou G. Electrochemical grippers based on the tuning of surface forces for applications in micro- and nanorobotics. Sci Rep 2023; 13:7885. [PMID: 37193686 DOI: 10.1038/s41598-023-33654-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 04/17/2023] [Indexed: 05/18/2023] Open
Abstract
Existing approaches to robotic manipulation often rely on external mechanical devices, such as hydraulic and pneumatic devices or grippers. Both types of devices can be adapted to microrobots only with difficulties and for nanorobots not all. Here, we present a fundamentally different approach that is based on tuning the acting surface forces themselves rather than applying external forces by grippers. Tuning of forces is achieved by the electrochemical control of an electrode's diffuse layer. Such electrochemical grippers can be integrated directly into an atomic force microscope, allowing for 'pick and place' procedures typically used in macroscopic robotics. Due to the low potentials involved, small autonomous robots could as well be equipped with these electrochemical grippers that will be particularly useful in soft robotics as well as nanorobotics. Moreover, these grippers have no moving parts and can be incorporated in new concepts for actuators. The concept can easily be scaled down and applied to a wide range of objects, such as colloids, proteins, and macromolecules.
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Affiliation(s)
- A Karg
- Physical Chemistry II, University of Bayreuth, Universitätsstraße 30, 95440, Bayreuth, Germany
| | - V Kuznetsov
- Physical Chemistry II, University of Bayreuth, Universitätsstraße 30, 95440, Bayreuth, Germany
| | - N Helfricht
- Physical Chemistry II, University of Bayreuth, Universitätsstraße 30, 95440, Bayreuth, Germany
| | - M Lippitz
- Experimental Physics III, University of Bayreuth, Universitätsstraße 30, 95440, Bayreuth, Germany
| | - G Papastavrou
- Physical Chemistry II, University of Bayreuth, Universitätsstraße 30, 95440, Bayreuth, Germany.
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Eskhan A, Johnson D. Microscale characterization of abiotic surfaces and prediction of their biofouling/anti-biofouling potential using the AFM colloidal probe technique. Adv Colloid Interface Sci 2022; 310:102796. [DOI: 10.1016/j.cis.2022.102796] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 10/11/2022] [Accepted: 10/14/2022] [Indexed: 11/16/2022]
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Xu K, Liu Y. Studies of probe tip materials by atomic force microscopy: a review. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2022; 13:1256-1267. [PMID: 36415853 PMCID: PMC9644057 DOI: 10.3762/bjnano.13.104] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 10/27/2022] [Indexed: 05/09/2023]
Abstract
As a tool that can test insulators' surface morphology and properties, the performance index of atomic force microscope (AFM) probes is the most critical factor in determining the resolution of microscopy, and the performance of probes varies in various modes and application requirements. This paper reviews the latest research results in metal, carbon nanotube, and colloidal probes and reviews their related methods and techniques, analyses the advantages and disadvantages of the improved probes compared with ordinary probes by comparing the differences in spatial resolution, sensitivity, imaging, and other performance aspects, and finally provides an outlook on the future development of AFM probes. This paper promotes the development of AFM probes in the direction of new probes and further promotes the broader and deeper application of scanning probe microscope (SPM).
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Affiliation(s)
- Ke Xu
- School of Electrical & Control Engineering, Shenyang Jianzhu University, Shenyang 110168, China
| | - Yuzhe Liu
- School of Electrical & Control Engineering, Shenyang Jianzhu University, Shenyang 110168, China
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