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Pandey S, Gautam D, Chen J. Measuring the Adsorption Cross Section of YOYO-1 to Immobilized DNA Molecules. J Phys Chem B 2024; 128:7254-7262. [PMID: 39014882 PMCID: PMC11286311 DOI: 10.1021/acs.jpcb.4c03359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Many interactions between small molecules and particles occur in solutions. They are surrounded by other molecules that do not react, for example, biological processes in water, chemical reactions in gas or liquid solutions, and environmental reactions in air and water. However, predicting the rate of such diffusive interactions remains challenging, due to the random motion of molecules in solutions, as exampled by the famous Brownian motion of pollen particles. In this report, we experimentally confirmed that a disruptive rate equation we have published before can predict the association rate of typical adsorption at interfaces, which has a surprising fraction order of 4/3 that has not been considered before. This could be an important step toward a generalized method to predict the adsorption rate of many reactions.
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Affiliation(s)
- Srijana Pandey
- Department of Chemistry and Biochemistry, Nanoscale & Quantum Phenomena Institute, Ohio University, Athens, OH 45701, USA
| | - Dinesh Gautam
- Department of Chemistry and Biochemistry, Nanoscale & Quantum Phenomena Institute, Ohio University, Athens, OH 45701, USA
| | - Jixin Chen
- Department of Chemistry and Biochemistry, Nanoscale & Quantum Phenomena Institute, Ohio University, Athens, OH 45701, USA
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Gündoğdu G, Yılmaz Topuzlu E, Mutlu F, Ertekin UE, Okur HI. Oil-in-Water Emulsions Probed Using Fluorescence Multivariate-Curve-Resolution Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:13116-13121. [PMID: 38861700 DOI: 10.1021/acs.langmuir.4c01018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
Hydrophobic surfaces in contact with aqueous media are omnipresent in nature. A plethora of key biological and physiological processes occur at the interface of immiscible fluids. Besides its fundamental importance, probing such interfaces is rather challenging, especially when one medium is bathed in the other. Herein, we demonstrate a fluorescence-based method that probes the oil-water interface and interfacial processes through surface dielectric perturbations. The fluorescence response of Nile Red is measured in hexadecane in water nanoemulsions. Three major spectral components appear: two from the bulk liquid media (hexadecane and water) and a distinct band at around 640 nm due to the interfacial component. Such spectra are deconvoluted using the multivariate-curve-resolution algorithm, and interface-correlated fluorescence spectra are attained. The influence of anionic sodium dodecylbenzenesulfonate (SDBS) and cationic cetyltrimethylammonium bromide (CTAB) surfactants on the oil-water interface is elucidated with concentration-dependent measurements. A charge-dependent spectral shift is observed. The interface correlated band at 641 nm for bare hexadecane nanoemulsions red shifts in the presence of anionic surfactants, indicating an apparent dielectric increase. In contrast, the same band gradually blue shifts with increasing cationic surfactant concentration, indicating an apparent interface dielectric decrease. Such a method can be utilized to probe alterations at interfaces beyond the oil/water interface.
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Affiliation(s)
- Gülsüm Gündoğdu
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
- National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey
- Department of Energy Science and Technology, Faculty of Science, Turkish-German University, Istanbul 34820, Turkey
| | - Ezgi Yılmaz Topuzlu
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
- National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey
| | - Ferhat Mutlu
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
| | - Umay E Ertekin
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
| | - Halil I Okur
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
- National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey
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Rauh F, Dittloff J, Thun M, Stutzmann M, Sharp ID. Nanostructured Black Silicon as a Stable and Surface-Sensitive Platform for Time-Resolved In Situ Electrochemical Infrared Absorption Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2024; 16:6653-6664. [PMID: 38267016 PMCID: PMC10859962 DOI: 10.1021/acsami.3c17294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/26/2024]
Abstract
Attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is a powerful method for probing interfacial chemical processes. However, SEIRAS-active nanostructured metallic thin films for the in situ analysis of electrochemical phenomena are often unstable under biased aqueous conditions. In this work, we present a surface-enhancing structure based on etched black Si internal reflection elements with Au-coatings for in situ electrochemical ATR-SEIRAS. Using electrochemical potential-dependent adsorption and desorption of 4-methoxypyridine on Au, we demonstrate that black Si-based substrates offer advantages over commonly used structures, such as electroless-deposited Au on Si and electrodeposited Au on ITO-coated Si, due to the combination of high stability, sensitivity, and conductivity. These characteristics are especially valuable for time-resolved measurements where stable substrates are required over extended times. Furthermore, the low sheet resistance of Au layers on black Si reduces the RC time constant of the electrochemical cell, enabling a significantly higher time resolution compared to that of traditional substrates. Thus, we employ black Si-based substrates in conjunction with rapid- and step-scan Fourier transform infrared (FTIR) spectroscopy to investigate the adsorption and desorption kinetics of 4-methoxypyridine during in situ electrochemical potential steps. Adsorption is shown to be diffusion-limited, which allows for the determination of the mean molecular area in a fully established monolayer. Moreover, no significant changes in the peak ratios of vibrational modes with different orientations relative to the molecular axis are observed, suggesting a single adsorption mode and no alteration of the average molecular orientation during the adsorption process. Overall, this study highlights the enhanced performance of black Si-based substrates for both steady-state and time-resolved in situ electrochemical ATR-SEIRAS, providing a powerful platform for kinetic and mechanistic investigations of electrochemical interfaces.
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Affiliation(s)
- Felix Rauh
- Walter
Schottky Institute, Technical University
of Munich, 85748 Garching, Germany
- Physics
Department, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany
| | - Johannes Dittloff
- Walter
Schottky Institute, Technical University
of Munich, 85748 Garching, Germany
- Physics
Department, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany
| | - Moritz Thun
- Walter
Schottky Institute, Technical University
of Munich, 85748 Garching, Germany
- Physics
Department, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany
| | - Martin Stutzmann
- Walter
Schottky Institute, Technical University
of Munich, 85748 Garching, Germany
- Physics
Department, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany
| | - Ian D. Sharp
- Walter
Schottky Institute, Technical University
of Munich, 85748 Garching, Germany
- Physics
Department, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany
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Chen J. Why Should the Reaction Order of a Bimolecular Reaction be 2.33 Instead of 2? J Phys Chem A 2022; 126:9719-9725. [PMID: 36520427 PMCID: PMC9805503 DOI: 10.1021/acs.jpca.2c07500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Predicting the reaction kinetics, that is, how fast a reaction can happen in a solution, is essential information for many processes, such as industrial chemical manufacturing, refining, synthesis and separation of petroleum products, environmental processes in air and water, biological reactions in cells, biosensing, and drug delivery. Collision theory was originally developed to explain the reaction kinetics of gas reactions with no dilution. For a reaction in a diluted inert gas solution or a diluted liquid solution, diffusion often dominates the collision process. Thus, it is necessary to include diffusion in such a calculation. Traditionally, the classical Smoluchowski rate is used as a starting point to predict the collision frequency of two molecules in a diluted solution. In this report, a different collision model is derived from the adsorption of molecules on a flat surface. A surprising result is obtained, showing that the reaction order for bimolecular reactions should be 2 and 1/3 instead of 2, following a fractal reaction kinetics.
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Affiliation(s)
- Jixin Chen
- Department of Chemistry and Biochemistry, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, OH 45701, USA
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