Unveiling Redox Enzyme Dynamics with Electrochemical X-ray scattering
A novel method, EC-SAXS (Electrochemical Small-Angle X-ray Scattering), has been developed to analyse structural differences in redox enzymes between their reduced and oxidized states. This technique provides valuable insight into enzyme conformational dynamics. Using bilirubin oxidase (BOD) as a model system, the study revealed that BOD transitions between open and closed conformations depending on its redox state – an observation with important implications for bioelectronics.
To enable these measurements, a custom device was created to perform simultaneous electrochemical and SAXS analyses, allowing real-time monitoring of redox-dependent structural changes. While SAXS coupled with electrochemistry has been widely applied in battery and fuel cell research, its application to biological systems has remained limited – EC-SAXS fills this gap. Figure 1 illustrates the structural analysis of redox enzymes using EC-SAXS, while Figure 2 shows the measurement setup.
Redox enzymes catalyse oxidation-reduction reactions by facilitating electron transfer between molecules. Understanding their structural variation between redox states is crucial for advancing bioelectronic devices such as biosensors and biofuel cells. Biosensors convert biochemical signals into electrical outputs for analyte detection (e.g., glucose), while biofuel cells harness redox enzymes to generate electricity from biological sources, powering devices like medical implants. These enzymes play a central role in sustainable energy conversion and biological monitoring. To fully harness their potential, redox enzymes must be immobilized on solid surfaces for stability, reusability, and efficient interaction with electrodes or substrates. While covalent binding to electrode surfaces offers high stability, it may restrict essential conformational flexibility, potentially reducing activity. Thus, understanding enzyme structural dynamics is essential for selecting appropriate immobilization strategies. However, traditional techniques have struggled to resolve structural differences between redox states.
Fig. 2: EC-SAXS cell setup. (a) Cell components: polyimide films with screen-printed electrodes, epoxy resin spacer (1.5 mm thick), and front/back epoxy parts with X-ray windows and mounting holes. (b) Cell setup inside the measurement chamber, connected to a potentiostat. (c) Fully assembled cell. (d) Cross-sectional schematic of the cell during measurement. WE, CE, and RE = Working, Counter, and Reference Electrodes
In this study, mediated Spectro electrochemical titration, in situ SAXS, and SAXS analysis were employed to investigate these changes. Results showed that reduced BOD maintains a more compact structure, while the oxidized form adopts an open conformation. High-resolution imaging confirmed this transition. The use of a concentrated phosphate buffer in EC-SAXS likely promoted expansion of the BOD structure in its oxidized state. This open conformation is functionally important, as it facilitates access for bilirubin, the natural substrate, which carries negatively charged carboxyl groups requiring open access to the enzyme’s active site. The EC-SAXS technique reveals that redox enzymes like BOD exhibit significant structural flexibility during redox cycling. By capturing these transitions, EC-SAXS provides critical insight into their reaction mechanisms. These findings could drive the development of optimized immobilization strategies, significantly enhancing the performance of biosensors, biofuel cells, and other bioelectronic devices. Ultimately, EC-SAXS has the potential to transform bioelectronics by enabling more efficient, sustainable & scalable technologies.
N. Loew; C. Miura et al.: Electrochemical small-angle x ray scattering for potential dependent structural analysis of redox enzymes, Langmuir, 41, no. 1 (2025) 383-391. doi: 10.1021/acs.langmuir.4c03661
Tokyo University of Science: Electrochemical X-ray scattering unlocks secrets of redox enzymes. phys.org/news/2025-01-electrochemical-ray-secrets-redox-enzymes.html
Unravelling the Mystery of Platinum Electrode Corrosion
Platinum is renowned for its durability and resistance to corrosion, making it ideal for electrochemical processes. However, a strange quirk has puzzled scientists for decades: while most metals are protected from corrosion when negatively polarized, platinum actually degrades under high negative potentials. This presents a challenge since devices like electrolysers often rely on negatively polarized platinum electrodes submerged in electrolyte—essentially saltwater. Two theories have attempted to explain this corrosion. One suggests sodium ions from the electrolyte infiltrate platinum’s atomic lattice, forming platinides that peel away. Another posits that sodium and hydrogen ions combine to create platinum hydrides, leading to degradation.
A recent study published in Nature Materials has finally uncovered the cause, that could help prevent platinum corrosion in electrolysers and other electrochemical devices. High-energy-resolution X-ray spectroscopy was developed to penetrate the electrolyte and isolate subtle changes in the platinum electrode during operation. A special pump and flow cell were designed to remove hydrogen bubbles that interfered with the X-ray experiment. By comparing experimental data with simulated spectra of platinum hydrides and platinides, the study confirmed that hydride formation at the platinum surface is responsible for its degradation (Fig. 3) [Collin Blinder]. This discovery provides crucial insights for improving the durability of platinum electrodes in electrolysers and other electrochemical systems.
T.J.P. Hersbach; A.T. Garcia-Esparza et al.: Platinum hydride formation during cathodic corrosion in aqueous solutions, Nat. Mater., 24 (2025) 574-580. doi: 10.1038/s41563-024-02080-y
Collin Blinder: Cracking the code: Why platinum electrodes corrode. https://phys.org/news/2025-01-code-platinum-electrodes-corrode.html
Indian Researchers Pioneer Eco-Friendly Hydrogen Peroxide Production
Scientists at the S.N. Bose National Centre for Basic Sciences, Kolkata, have developed a sustainable and energy-efficient method to produce hydrogen peroxide (H2O2) using sunlight and covalent organic frameworks (COFs). This photocatalytic process, powered by a 40 W blue LED or sunlight, reduces reliance on the conventional energy-intensive anthraquinone oxidation method, which produces hazardous by-products.
Scientists are therefore looking for an environmentally friendly and economical strategy to produce H2O2 from renewable resources with minimal environmental impact. In this context, a new class of porous and ordered polymers with modifiable catalytic sites and light-harvesting properties in the visible range, called covalent organic frameworks (COFs), have emerged as promising photocatalysts.
By modifying the hydrazone linkage density in COFs, the researchers enhanced key chemical reactions (water oxidation and oxygen reduction) essential for H2O2 synthesis. Using an aqueous benzyl alcohol solution further improved production efficiency while preventing degradation. This breakthrough offers a cleaner, cost-effective alternative for large-scale H2O2 manufacturing, with far-reaching applications in industries like disinfection, paper bleaching, and chemical synthesis. It promises to deliver a greener and more sustainable solution for the future.
The hydrazone-linked COF exhibited exceptional photocatalytic H2O2 production without external sacrificial electron donors when irradiated with a 40 W blue LED (λ = 467 nm). A significant amount of H2O2 (550 μmol g-1 h-1) was also produced under sunlight irradiation, outperforming most organic photocatalysts under similar conditions and demonstrating a clean and sustainable pathway. Furthermore, these COFs can generate H2O2 up to 21641 μmol g-1 h-1 using an aqueous benzyl alcohol solution (water: benzyl alcohol = 90:10), which prevents H2O2 degradation.
Fig. 4: Schematic route of the photocatalytic synthesis of H2O2 and its end uses
This strategy of using a mixture of water-benzyl alcohol solution is promising for developing a continuous flow reactor for sustainable H2O2 production, facilitating laboratory-to-industry technology transfer for societal benefit. Figure 4 presents a schematic route of the photocatalytic synthesis of hydrogen peroxide and its various end uses.
Hydrogen peroxide is a versatile oxidizing agent widely used in environmental disinfection, chemical synthesis, paper bleaching, and fuel cells. The market for H2O2 is driven by increasing awareness of disinfection, rising surgical procedures, and the prevalence of hospital-acquired infections. Currently, over 95 % of H2O2 is produced industrially using the anthraquinone oxidation process, which is energy-intensive, expensive, and generates hazardous by-products. This new COF-based photocatalytic method presents an environmentally friendly and economical alternative for H2O2 production from renewable resources with minimal environmental impact.
https://www.daijiworld.com/news/news-Display?newsID=1274521 . Daijiworld Media Network-Kolkata
https://pib.gov.in/PressReleaseIframePage.aspx?PRID=2109125
https://www.thehindubusinessline.com/business-tech/hydrogen-peroxide-eco-friendly-synthesis/article69310501.ece
https://thenewshashtag.com/indian-scientists-develop-sustainable-method-for-hydrogen-peroxide-production/#google_vignette
An Electrochemical Analogy of the Current Reciprocal Tariff War
Trade imbalances can be likened to concentration gradients in electrochemical cells, where the spontaneous flow of goods and capital under free trade parallels ion diffusion toward equilibrium. The imposition of tariffs acts as an externally applied potential in an electrolytic cell, forcing a non-spontaneous reversal of this natural flow. Such a shift requires continuous energy input–manifested as economic strain, elevated consumer costs, and geopolitical tension–with the aim of restructuring trade dynamics toward a more favourable, albeit costly, economic configuration.
