Complex Formation Research Articles

Using Poly(amidoamine) PAMAM-βCD Dendrimer for Controlled and Prolonged Delivery of Doxorubicin as Alternative System for Cancer Treatment

Background/Objectives: Doxorubicin (Dox) is an anticancer drug used in the treatment of a wide range of solid tumors; however, Dox causes systemic toxicity and irreversible cardiotoxicity. The design of a new nanosystem that allows for the control of Dox loading and delivery results is a powerful tool to control Dox release only in cancer cells. For this reason, supramolecular self-assembly was performed between a poly(amidoamine) (PAMAM) dendrimer decorated with four β-cyclodextrin (βCD) units (PAMAM-βCD) and an adamantane–hydrazone–doxorubicin (Ad-h-Dox) prodrug. Methods: The formation of inclusion complexes (ICs) between the prodrug and all the βCD cavities present on the surface of the PAMAM-βCD dendrimer was followed by 1H-NMR titration and corroborated by 2D NOESY experiments. A full characterization of the supramolecular assembly was performed in the solid state by thermal analysis (DSC/TGA) and scanning electron microscopy (SEM) and in solution by the DOSY NMR technique in D2O. Furthermore, the Dox release profiles from the PAMAM-βCD/Ad-h-Dox assembly at different pH values was studied by comparing the efficiency against a native βCD/Ad-h-Dox IC. Additionally, in vitro cytotoxic activity assays were performed for the nanocarrier alone and the two supramolecular assemblies in different carcinogenic cell lines. Results: The PAMAM-βCD/Ad-h-Dox assembly was adequately characterized, and the cytotoxic activity results demonstrate that the nanocarrier alone and its hydrolysis product are innocuous compared to the PAMAM-βCD/Ad-h-Dox nanocarrier that showed cytotoxicity equivalent to free Dox in the tested cancer cell lines. The in vitro drug release assays for the PAMAM-βCD/Ad-h-Dox system showed an acidic pH-dependent behavior and a prolonged profile of up to more than 72 h. Conclusions: The design of PAMAM-βCD/Ad-h-Dox consists of a new controlled and prolonged Dox release system for potential use in cancer treatment.

Insights into rare earth element speciation: unraveling sulfate and hydrolysis complexes through DFT calculations.

Rare earth elements (REE) are indispensable in numerous green technologies owing to their exceptional physical and chemical attributes. Separating REE is a pivotal process to meet the increasing demands of the high-tech industry. Understanding the hydrolysis of REE in aqueous environments marks the initial stride in comprehending their separation mechanisms. Sulfate commonly coexists in high-concentration solutions alongside REE, stemming from mineral processing. We analyzed the hydrolysis of REE and their complexes with sulfate using DFT methods. We present and discuss on the structural characteristics of hydrolysis species and sulfate complexes in alignment with existing experimental data. Estimates of Gibbs free energies for hydrolysis and sulfate complex formation were compared against literature values. REE pose challenges owing to the labile nature of aqua complexes and the pivotal role of system dynamics. We showed that hydrolysis reactions could be suitably modeled, yielding an error margin of approximately 5kcalmol-1 concerning experimental values, employing the M06 exchange-correlation functional with the SMD implicit solvation model. However, sulfate chemical species proved to be more challenging, exhibiting larger error margins with substantial variations across the REE series. The Raman spectrum analysis of lanthanum sulfate complexes demonstrated excellent agreement with experimental values. We applied the M06, PBE, and PBE0 exchange-correlation functionals combined with def2-TZVP basis sets and SMD to obtain the Gibbs free energies of hydrolysis and sulfate complexation with lanthanides in aqueous solution. The calculations were performed using the ORCA program.

Cryo-EM Structure of AAA + ATPase Thorase Reveals Novel Helical Filament Formation.

The AAA+ (ATPases associated with a variety of cellular activities) ATPase, Thorase, also known as ATAD1, plays multiple roles in synaptic plasticity, mitochondrial quality control and mTOR signaling through disassembling protein complexes like AMPAR and mTORC1 in an ATP-dependent manner. The Oligomerization of Thorase is crucial for its disassembly and remodeling functions. We show that wild-type Thorase forms long helical filaments in vitro, dependent on ATP binding but not hydrolysis. We report the Cryogenic Electron Microscopy (cryo-EM) structure of the Thorase filament at a resolution of 4 Å, revealing the dimeric arrangement of the basic repeating unit that is formed through a distinct interface compared to the hexameric MSP1/ATAD1E193Q assembly. Structure-guided mutagenesis confirms the role of critical amino acid residues required for filament formation, oligomerization and disassembly of mTORC1 protein complex. Together, our data reveals a novel filament structure of Thorase and provides critical information that elucidates the mechanism underlying Thorase filament formation and Thorase-mediated disassembly of the mTORC1 complex.

Physical modelling of salt structural deformation in the Tajik Basin: insights into the formation of complex fold-and-thrust structures

Physical modelling of salt structural deformation in the Tajik Basin: insights into the formation of complex fold-and-thrust structures

Multifunctional curcumin/γ-cyclodextrin/sodium chloride complex: A strategy for salt reduction, flavor enhancement, and antimicrobial activity in low-sodium foods

Excessive salt consumption is strongly linked to the chronic diseases development, highlighting the urgent need for effective salt-reduction strategies in food products. However, reducing salt content often compromises both food preservation and flavor. In this study, we hypothesized that curcumin could enhance the flavor perception of sodium chloride while compensating for its antimicrobial effect in reduced-salt applications. To test this, we developed a curcumin/γ-cyclodextrin/sodium chloride complex (IC), using γ-cyclodextrin as a carrier, and evaluated its antimicrobial and flavor-enhancing properties. The complex's formation was confirmed through various analytical techniques. Results from electronic tongue and sensory evaluations demonstrated that the IC enhanced the perception of saltiness and imparted unique aromatic characteristics compared to standard sodium chloride. GC-IMS analysis identified key aroma contributors, such as aldehydes and alcohols. Additionally, antimicrobial tests revealed that the IC efficiently mediated the sono/photodynamic inactivation of Shewanella putrefaciens and Vibrio parahaemolyticus. In summary, the IC offers a multifunctional approach, enhancing flavor, reducing salt, and enabling antimicrobial activity, while promoting practical uses of sono/photodynamic technology in low-sodium foods.

Fabrication and characterization of PVDF/PMMA nanocomposite membranes doped with graphene oxide (GO) for separation of CO2/CH4 from flue gas

This work focuses on developing polyvinylidene fluoride/polymethyl methacrylate (PVDF/PMMA) polymer blend nanocomposites incorporating varying concentrations of graphene oxide (GO) nanoparticles fabricated via casting solution processes. XRD and FT-IR confirmed GO-induced structural modifications in PVDF/PMMA blend. The addition of GO into PMMA/PVDF blend decreased and weakened the intensity of XRD peaks, suggesting that adding GO gradually reduces the crystallinity of the films. FT-IR verified miscibility and complex formation between the pristine polymer blend and the GO-filled nanocomposite. The incorporation of GO caused shifts in the optical absorption edge to lower wavelengths, causing a decrease in the optical bandgap energy (Eg). The real and imaginary parts of the dielectric permittivity (ε′ and ε′′), electric modulus (M′, M″), and AC conductivity (σac) have been measured from 0.1 Hz to 6 MHz. Both ε′ and ε′′ declined with rising frequency. The addition of different concentrations of GO generated charge transfer complexes in the polymer nanocomposites. SEM images show good homogeny with random dispersion of GO inside the polymer blend. The thermoluminescence (TL) glow curves for the nanocomposite samples irradiated 0.5, 1.0, 1.5, and 2 Gy doses show peak cantered at 207 °C. The peak position remained unchanged with increasing irradiation dosage. The dose-dependent linear growth in maximum peak height indicates radiation detection and monitoring capability.

Suppression Effect of Sn on Irregular Shape Deposition of Zn for Negative Electrode of Large-Scale Energy Storage Devices

Zn is one of the promising negative electrode materials for next-generation large-scale energy storage device. This is ascribed to its several advantages: (1) it shows high energy density, (2) aqueous solvent is to be used, which can prevent hazardous accident, or (3) it is abundant material. In order to put the electrode into practice, it is necessary to develop innovative electrolyte that contains effective additives to prevent shape-changes of the electrode. The undesirable phenomena taking place on the electrode surface should degrade the performance of the electrode, such as cyclabilities and current efficiencies. In particular, a filament-like deposition of Zn, what we call a “mossy” structure, is a serious problem. It takes place under relatively low overpotential environment, which is different mode from a dendritic growth under high overpotential range. The mossy structure has been a big interest and our past study explained the mechanism underlying the structure in terms of diffusivity of deposited Zn atom on the electrode surface.1 We also try to find effective additives to prevent the mossy structure: heavy metals, such as Pb2 or Sn3, are now one of the candidates. For more precise controls of the shape-change of the electrode, such effective additives are to be analyzed in detail, so that we understand the key to controlling deposition behavior of Zn. This study performed both theoretical calculation with DFT, and electrochemical measurements to identify working mechanism of Sn that mitigates mossy formation on Zn in strongly alkaline solution. Polarization curves indicated that Sn should work as a suppressor for mossy in the form of [Sn(OH)6]2- ion. It is due to high concentration of OH- in KOH. The results also showed that the complex form is so stable that Sn is not likely to be reduced and deposited on Zn electrode surface. DFT calculation with ESM-RISM, based on the experimental results, evaluated the additive effect of the [Sn(OH)6]2-, by comparing an energy diagram of [Zn(OH)4]2- reduction with the Sn complex to that of without it. It turned out that [Sn(OH)6]2- facilitated reduction of [Zn(OH)4]2-, by interacting with its intermediate. According to a statistic model we formerly proposed, the interaction should effectively suppress the mossy growth of Zn. The theoretical results were in good agreement with electrochemical impedance spectroscopy measurements.AcknowledgementsThis work was supported by JSPS KAKENHI Grant Number JP21H01642.

Investigation of the Effects of Glycine in Ni Electrodeposition: Local pH Measurement and Its Mathematical Modelling

Ni is an important material in surface finishing for both decorative and functional purposes [1]. In order to change the properties of plating baths and to improve the quality of products, various kinds of additives are typically employed in Ni electroplating. However, a comprehensive understanding of the roles of additives is still lacking due to the complexity of the systems, in which multiple chemical species are involved in parallel chemical/electrochemical reactions. Glycine (Gly) is widely utilized both in electro- and electroless plating, and it is believed to work as a complexing agent and as a buffer. However, studies on this species are still limited [2-3], and an even deeper understanding of its effects is desired to enable us to tune and optimize plating processes. In a system containing glycine as well as metal species such as Ni, the situation is complicated by the fact that the electrodeposition of metal almost always accompanies the hydrogen evolution reaction (HER). As protons near the cathode surface are consumed by the production of hydrogen, the near-surface pH increases during the electrodeposition process, which results in shifting the equilibria of glycine species and promoting the formation of metal-glycine complexes. To elucidate this kind of complicated system and to be able to predict its behavior, it is necessary to combine various electrochemical methods and theoretical approaches such as mathematical modelling. In this study, the effects of glycine in Ni electrodeposition were investigated both theoretically and experimentally. First, thermodynamic calculations were carried out to predict the stabilities of Ni-glycine species at different pH and potentials. It was illustrated that glycine indeed stabilizes Ni species in an aqueous solution, as has been pointed out by many studies, preventing the formation of Ni(OH)2 even at high pH. Electrochemical measurements such as linear sweep voltammetry (LSV) were performed to investigate the electrochemical behavior of the Ni-glycine species. Due to the involvement of glycine in the equilibria as mentioned above, the local pH near the cathode surface is particularly important. Therefore, we employed a rotating ring-disk electrode (RRDE) with a metal oxide-based pH sensor coated on the ring electrode. The local pH was successfully measured along with the electrochemical responses at the disk electrode. Furthermore, a mathematical model of the Ni-glycine system was developed taking into account the chemical equilibria and the mass transfer of species as well as the electrochemical reactions at the cathode surface. The experimental results will be discussed in connection with the theoretical predictions made by the mathematical model.

Electrodeposition for Metal Recovery from Spent Batteries: Strategies for Improving Selectivity

Selective recovery of critical metals such as cobalt and nickel at a molecular level is crucial for the sustainable recycling of Li-ion batteries. However, the similarity in reduction potentials between these metals presents a significant challenge for achieving selectivity during electrodeposition, particularly for elements like cobalt and nickel (with E°Co = −0.277 V and E°Ni = −0.250 V vs SHE). In this presentation, we introduce a key strategy aimed at controlling selectivity toward either cobalt or nickel during potential-dependent electrodeposition. Initially, manipulating the electrolyte composition to introduce an excess of chloride ions enables precise control over speciation, leading to the distinct formation of anionic cobalt chloride complexes (CoCl42-) while keeping nickel predominantly in its cationic form ([Ni(H2O)5Cl]+) within an aqueous electrolyte. This forms the basis for potential-dependent selectivity. Additionally, regulating the interfacial charge density through electrode functionalization further fine-tunes selectivity by controlling the diffusion coefficient of the target ions. Moreover, we demonstrate the effectiveness of temperature-dependent control in achieving selectivity, resulting in a Ni/Co ratio exceeding 100. Unlike traditional selective electrodeposition methods, where the extended enrichment of one metal on the solid surface adversely impacts dynamic selectivity due to concentration change in the bulk electrolyte, our innovative approach guarantees high-purity and high-recovery metal extraction even during prolonged electrodeposition. This study presents a hopeful prospect for selective electrodeposition as a proficient separation method in battery recycling procedures.

Glycosylation analysis of transcription factor TFIIB using bioinformatics and experimental methods

Transcription is a fundamental process involving the interaction of RNA polymerase II and related transcription factors. TFIIB is a transcription factor that plays a significant role in the formation and stability of the preinitiation complex in a precise orientation, as well as in the control of initiation and pre-elongation steps. At the initiation step, TFIIB interacts with three structures: the end of the TATA-binding protein, a GC-rich DNA sequence followed by the TATA box, and the C-terminal domain of RNA polymerase II. It is known that RNA polymerase II is a glycoprotein and contains O-GlcNAc sugar at the C-terminal domain during the initiation stage of transcription. However, it is unclear whether the transcription factors interacting with RNA polymerase II are glycoproteins or not. The study aims to determine the glycosylation (N- and/or O-linked glycosylations) of TFIIB by using bioinformatics in one invertebrate and seven vertebrate species and experimental methods in the sea urchin Paracentrotus lividus oocyte. Both bioinformatics and experimental analysis have shown that TFIIB is a glycoprotein. In addition, PNGase-F enzyme treatment, lectin blotting, and colloidal-gold conjugated lectin labeling results revealed that TFIIB contains O-linked GalNAc, mannose, GlcNAc, and α-2,3-linked sialic acid. Based on our results, we suggest that glycosylation modification may be involved in the transcription mechanism of the TFIIB protein.

Competitive adsorption mechanisms of phosphorus species on montmorillonite-iron oxyhydroxide complexes

Phosphorus (P) biogeochemical cycle in subsurface environments is primarily mediated by various minerals. However, there is still unknown about the impact of iron (Fe) oxyhydroxides coexisting with clay on the fate of different P species. Here, the interfacial behavior for competitive adsorption of phytate and phosphate on montmorillonite-Fe oxyhydroxide (Mt-amFe) complexes was comprehensively investigated. The nucleation of amorphous Fe oxyhydroxides on montmorillonite contributes to the formation of Mt-amFe complexes and consequently the surface properties of clay are altered. Phytate is preferentially adsorbed on the complexes and the adsorption capacity for phytate is 5.8 times higher than that for P at a mass ratio of 1:1 during the competitive adsorption process. Moreover, during their competition adsorption on Mt-amFe, the interactions between Fe and clay generally tend to decrease the mass ratio of phytate and phosphate in aqueous phases, which is tightly associated with the risk of P contamination. As shown by solid characterization, the adsorption of P species is mainly attributed to inner-sphere complexation. To illustrate the thermodynamic mechanisms for the competitive adsorption effects, dynamic force spectroscopy was applied to quantify the immobilization of different species of P on Mt-amFe complexes, and the results show that phytate is more thermodynamically favorable for the complexation with minerals compared with that of phosphate. These findings can guide the prediction of P loss risk associated with the differences in P species in subsurface environments based on the analysis of mineral surface structures.

A stepwise mode of TGFβ-SMAD signaling and DNA methylation regulates naïve-to-primed pluripotency and differentiation

The formation of transcription regulatory complexes by the association of Smad4 with Smad2 and Smad3 (Smad2/3) is crucial in the canonical TGFβ pathway. Although the central requirement of Smad4 as a common mediator is emphasized in regulating TGFβ signaling, it is not obligatory for all responses. The role of Smad2/3 independently of Smad4 remains understudied. Here, we introduce a stepwise paradigm in which Smad2/3 regulate the lineage priming and differentiation of mouse embryonic stem cells (mESCs) by collaboration with different effectors. During the naïve-to-primed transition, Smad2/3 upregulate DNA methyltransferase 3b (Dnmt3b), which establishes the proper DNA methylation patterns and, in turn, enables Smad2/3 binding to the hypomethylated centers of promoters and enhancers of epiblast marker genes. Consequently, in the absence of Smad2/3, Smad4 alone cannot initiate epiblast-specific gene transcription. When primed epiblast cells begin to differentiate, Dnmt3b becomes less actively engaged in global genome methylation, and Smad4 takes over the baton in this relay race, forming a complex with Smad2/3 to support mesendoderm induction. Thus, mESCs lacking Smad4 can undergo the priming process but struggle with the downstream differentiation. This work sheds light on the intricate mechanisms underlying TGFβ signaling and its role in cellular processes.

Facet-Dependent Adsorption of Rare Earth Elements (REEs) and Actinides onto Goethite: REE Pattern Variability and Cerium Anomaly.

Assessing the fate of contaminants in the environment requires a deep understanding of intrinsic adsorption mechanisms on natural minerals such as Fe-oxyhydroxides. In this study, we proposed an innovative approach to probe site heterogeneities on the goethite surface by comparing the adsorption behavior of rare earth elements (REEs, including Sc, Y, and all lanthanides; Ln) except Pm, as well as Th and U. A surface loading-dependent adsorption of Ln and Y was observed, with a shift from (i) preferential middle to heavy REE adsorption and (ii) limited to substantial fractionation between Y and Ho as the loading increased. These observations are likely attributable to the formation of strong and weak complexes onto the (021) and (110)/(100) goethite faces at low and high loadings, respectively. Additionally, Ce-anomaly, characteristic of Ce(III) partial oxidation to Ce(IV), was observed only at high loading. By drawing an analogy with Th(IV) and Sc(III), Ce(IV) is expected to outcompete Ln(III) and Y adsorptions and stabilize primarily at the strong sites on the (021) face, even under conditions of high loading. The outcome of this study, supported by charge distribution-multisite complexation (CD-MUSIC) calculation, provides new insights into the impact of facet-dependent adsorption and redox processes on Fe-oxyhydroxides.

(Invited) Novel Biosensing Platform Based on Image Analysis of Rotational Diffusion of Probe-Modified Janus Particles

Infectious diagnosis of high-risk viruses and pathogenic bacteria is made by PCR testing. RNA virus testing is performed through multiple steps of sample collection, RNA extraction, reverse transcription, and amplification by PCR. Present methods are problematic due to the length of testing time and complexity of the operation.In this study, we focus on the rotational Brownian motion of probe-modified particles and develop a new biosensor that is specific, quick, and simple to detect target DNA/RNA by photographing the rotational Brownian motion of probe-modified particles with a microscope and analyzing the diffusivity, which is the degree of the motion(Fig. A). The Stokes-Einstein-Debye equation, which considers the rotational motion of particles in solution, shows that the rotational diffusivity of particles is inversely proportional to the third power of the particle diameter when the ambient temperature and viscosity of the medium are controlled. In the case of Janus particles, which emit fluorescence only on half their surface, the rotational diffusivity corresponds to the correlation time, which is the correlation intensity per elapsed time of the flashing signal obtained from the rotational Brownian motion of the particles. Based on the above principle, we conducted experiments and found that under the presence of target RNA, Janus particles capture RNA, which leads to the formation of Janus particle-RNA complexes and an increase in particle volume, which in turn leads to an increase in correlation time (Fig. B). Also, the correlation time of the target RNA-Janus particle complex increases with an increase in the target RNA concentration (Fig. C). Furthermore, it was confirmed that the sensitivity and specificity of this sensor reached 85% and 100%, respectively. Since the correlation time can be measured only by microscopic observation and does with no amplification, this sensor is expected to be a simple and rapid detection.

Field-Effect Transistor Biosensor By Capture of Nucleic Acid Strands with Isothermal Amplification for RNA Detection

Nucleic acid amplification methods are widely used for sensitive detection of biomolecules utilizing signals derived from amplified DNA strands[1]. Signal amplification by ternary initiation complexes (SATIC) has been attracted attention as high specific RNA detection method, because rolling circle amplification (RCA) by φ29 DNA polymerase requires the formation of ternary initiation complexes with DNA primers, circular DNA templates, and target RNAs[2]. In SATIC system, target RNA was detected via fluorescence derived from the complex of guanine quadruplex (G4) structure, which generated within the amplified DNA strands, and thioflavin T (ThT)[3]. To further simplify RNA detection using the SATIC system, it was expected to be effective to combine it with a field-effect transistor (FET) biosensor. A FET biosensor detects target molecules by altering the interfacial potential through the adsorption of charged molecules, thereby enabling simple label-free detection. Previously, we demonstrated the RNA detection via the negative charges of amplified DNA strands using the SATIC system, which originated from the DNA primer-immobilized FET sensor surface[4]. This approach will be required the immobilization of different DNA primers for the detection of various targets. As the immobilization conditions of the DNA primers needed to be optimized for detection of each target RNA, there was concern that the versatility of the FET biosensor would be reduced. Here, the versatility of the FET biosensor could be reinforced by the capture of nucleic acid strands amplified in the bulk by the sensing interface formed under the same conditions. For the realizing the above approach, the interaction between the G4 structure and ThT was considered to be effective in capturing amplified DNA strands. In this study, we attempted to detect target RNA by capture of the amplified DNA strands containing the G4 structures using ThT-immobilized FET biosensor.ThT derivatives (ThT-OE11[5]) were immobilized to aminopropylsilane-modified FET gate surface via cross-linking by glutaraldehyde (1 h). After that, residual aldehyde group were capped by the ethanolamine (1 h). Subsequently, amplified DNA strands were generated by mixing target RNAs, DNA primers, circular DNA templates, the four deoxynucleotide triphosphates (dNTPs), and φ29 DNA polymerase at 37°C. Following that, the SATIC reaction solution was added to the ThT-immobilized FET (30 min.). Finally, the gate voltage (V g)-drain current (I d) characteristics were measured before and after the addition of the SATIC reaction solution for calculating gate voltage shift (ΔV g).The FET response to 100 nM target RNA was measured when the SATIC reaction solution was added ThT-immobilized FET biosensor. As shown in Figure 1(a), ΔV g in the positive direction was obtained, indicating that the electron concentration in the channel was decreased by electrostatic interaction from negative charges of the amplified DNA strands. To optimize ThT immobilization condition, we evaluated the relationship between concentrations of ThT-OE11 solution and the sensor responses to target RNA. As a result, maximum response obtained at 500 mM ThT-OE11 solution. Subsequently, the sensor signal to 1 base-mismatched RNA as a negative control was almost no response (Figure. 1(b)). This result suggested that the nucleic acid strands were not generated by SATIC system, because the ternary initiation complexes did not form with 1 base-mismatched RNA. Thus, the ThT-immobilized FET with SATIC system specifically detected target RNAs. Finally, the measurement of ΔV g at different concentrations of target RNAs were conducted using ThT-immobilized FET to examine the quantitative detectability. As a result, ThT-immobilized FET with SATIC system showed a concentration dependence in the range of 1 pM to 100 nM. In addition, we plan to obtain additional data on sensitivity by controlling the reaction time of FET biosensor with SATIC system. From these results, the capture of nucleic acid strands containing G4 structure by ThT-immobilized FET could be effective for RNA detection.[1] M. Falco et al., TrAC Trends in Anal. Chem., 2022, 148, 3, 116538[2] H. Fujita et al., Anal. Chem., 2016, 88, 7137−7144[3] J. Mohanty et al., J. Am. Chem. Soc., 2013, 135, 1, 367–376[4] H. Hayashi et al., Talanta, 2023, 273, 125846[5] M. Kuwahara et al., Molecules, 2020, 25, 4936 Figure 1

(Invited) Stabilization and Activation of Cuprous Oxide Photocathodes for Effective Reduction of Carbon Dioxide

Among representative examples of semiconducting materials for the selective reduction of carbon dioxide to desired small organic molecules (fuels, utility chemicals), there are transition metal oxides (p-type semiconductors), in particular Cu-based oxides, such as Cu2O, CuFeO2, CuBi2O4, CuNb2O6, CuO and Cu2O) that are capable of generating electrons with use of solar visible light. Selectivity of the catalytic systems largely depends on the activing adsorptive (CO2) phenomena and the affinity of catalytic centers to the adsorbed carbon monoxide intermediates leading to their protonation or hydrogenation. Here application of aqueous or water-containing electrolytes is generally preferred. Furthermore, a compromise must be reached between the activity of a catalyst toward hydrogen evolution (water splitting), its ability to promote reductive adsorption of CO2 and to generate moderate coverages of H atoms capable of stabilizing subsequent reduced intermediates.Our interest concentrates on copper(I) oxides but their practical use requires means of stabilization without poisoning or deactivation. To improve stability against photocorrosion, to assure the sufficient electron-hole pair separation, as well as to increase population of electrons in the conduction band, mixed oxide systems combining the p-type semiconductor (e.g. Cu2O) with n-type semiconductors such as TiO2, SrTiO3 or KTaO3 have been proposed. To meet requirements for practical Cu2O-based photocathodes, not only the ability to absorb efficiently visible light and to assure fast interfacial electron transfers but also the stability issues need to be addressed.Contrary to the poor performance of the pristine (bare) copper(I) oxide photocathode, the visible-light-illuminated photoelectrochemical reduction of carbon dioxide has been successfully performed using the p-type Cu2O-semiconductor (deposited onto the transparent fluorine-doped conducting glass electrode) over-coated with the ultra-thin films of various polymer (poly(4-vinyl pyridine, oligoaniline) or polynuclear type materials (titanium, zirconium and tungsten oxides).. In this respect, ultra-thin films of functionalized carbon nanostructures, supramolecular complexes (with nitrogen containing ligands and certain transition metal sites) or robust bacterial biofilms could also be advantageous. For example, A biofilm formed by a strain of Yersinia enterocolitica (Y. enterocolitica) is characterized by high physicochemical stability over a wide pH range (4-10) and temperatures (0-40°C).Also oligoaniline or tungsten oxide over-layers could be fabricated on copper(I) oxide surfaces. Under such conditions, the copper(I) oxide photoelectrode does not change the oxidation state during photoelectrochemical diagnostic experiments. Thus certain robust (not necessarily thin) over-layers could exhibit the effect of stabilization of Cu2O against photocorrosion. Among important issues is the ability of CO2 to undergo adsorption (and activation toward reduction to CO) at both bare and modified surfaces of Cu2O. The proposed bi-layered photocathode has been demonstrated to produce such simple organic fuels as alcohols. Introduction of co-catalytic centers, e.g. palladium in a form of supramolecular complexes could also be advantageous.

Impact of Natural Organic Matter (NOM) on Nitrate Adsorption in the Membrane Capacitive Deionization (MCDI) Process

Fertilizers containing nitrates significantly boost agricultural productivity, resulting in their extensive application in many regions. However, the majority of nitrate found in water originates from these fertilizers, leading to a gradual increase in nitrate concentration. Nitrogen-catalyzed eutrophication of surface waters leads to algal blooms, resulting in deterioration of water resources. Overexposure to nitrate has adverse effects on plants, the health of animals and humans. The contamination of water resources due to nitrates is becoming a serious issue. Thus, addressing the necessity of nitrate removal becomes important in safeguarding both environmental sustainability and public health. A variety of water treatment technologies for nitrate removal have been developed. Recently, membrane Capacitive Deionization (MCDI) is widely utilized for nitrate removal due to its high ion adsorption capability and selectivity. Meanwhile, there has been insufficient investigation regarding the effect of natural organic matters (NOM) found in natural water resources, which is expected to significantly degrade the salt adsorption capacity of MCDI. Moreover, the mechanism of NO3− adsorption in the presence of NOM in the electrosorption process has not yet been shown clearly. Therefore, more research efforts are needed to investigate the effect of NOM and its significance on MCDI to effectively remove nitrate during operation. In this study, we investigated the influence of NOM on the adsorption of nitrate in the MCDI process. Feed water with and without NOM was analyzed to examine changes in the performance of nitrate adsorption. This study will introduce a decrease in nitrate adsorption rates in water containing NOM due to the formation of complexes facilitated by organic matter.

Electrochemical Study Towards a Better Understanding of Induced Codeposition with Silver

The reduction of tungstate and molybdates ions in aqueous solution is often referred as induced codeposition. Those ions can only be reduced to a metallic state alongside another element. Researches on Ni-W and Ni-Mo suggested the formation of an adsorbed bimetallic complex formation step before reduction of the induced element [1]. Cobalt and iron, sharing many properties with nickel, are also reported as inducing element for Tungsten and or Molybdenum codeposition [2]. Recently, the list of inducing elements was enlarged with a study describing Zn-W induced codeposition and highlighting the role of citrate in complexing both zinc and tungstate ions separately [3]. Cu-W induced codeposition was similarly achieved in citrate electrolyte, suggesting that noble metals were also susceptible to act as inducing elements for tungsten [4]. Podlaha’s group reported silver-tungsten codeposition from thiourea-citrates electrolytes [5]. While the authors describe thiourea as the ligand of the bimetallic complex, the role of the citrates ions and their protonated forms remains unclear.Silver-tungsten alloys grew a recent interested because of their potential use in connector application. Silver exhibits the highest thermal and electrical conductivities among all metals but has poor mechanical properties and remains vulnerable to sulphuration. Therefore, introducing tungsten, a very resistant metal both chemically and mechanically, as an alloying element of silver would create a high performances alloy particularly suited for high power connectivity applications. Alkaline cyanide is the most widely spread method of complexing silver in a plating process, but emergence of new environmental issues tends to limit the use of hazardous species.The present study is part of the SILAHPERF project, led by IRT-M2P and UTINAM Institute, which try to investigate the codeposition mechanism of various silver-based alloys of interest with a particular focus on silver-tungsten while seeking for environmental-friendly solutions. Previous works showed that silver tungsten codeposition was possible from a completely non-toxic electrolyte, using 5,5-dimethylhydantoin and citrates as complexing agents [6]. However, facing stability issues, this plating bath need further developments before its industrial scale deployment.Modification of pH and use of tartrates ions showed that the protonated carboxyl functional groups play a major role in silver-tungsten induced codeposition. To deeper insights into the mechanism, experimentations were conducted using a wide array of complexing agents. Those compounds are chosen depending on the nature and the number of functional groups they show whether it be hydroxyl, carboxyl, or amino ones. The influence of pH and concentrations ratios is investigated for each candidate. Eventually, this study is extended to molybdenum which presents the same induced deposition behaviour.[1] O. Younes-Metzler, L. Zhu, and E. Gileadi, ‘The anomalous codeposition of tungsten in the presence of nickel’, Electrochimica Acta, vol. 48, no. 18, pp. 2551–2562, Aug. 2003,[2] N. Eliaz and E. Gileadi, ‘Induced Codeposition of Alloys of Tungsten, Molybdenum and Rhenium with Transition Metals’, in Modern Aspects of Electrochemistry, vol. 42, C. G. Vayenas, R. E. White, and M. E. Gamboa-Aldeco, Eds., in Modern Aspects of Electrochemistry, vol. 42. , New York, NY: Springer New York, 2008, pp. 191–301.[3] H. Kazimierczak and N. Eliaz, ‘Induced Codeposition of Tungsten with Zinc from Aqueous Citrate Electrolytes’, Coatings, vol. 13, no. 12, p. 2001, Nov. 2023[4] P. Bacal, P. Indyka, Z. Stojek, and M. Donten, ‘Unusual example of induced codeposition of tungsten. Galvanic formation of Cu–W alloy’, Electrochemistry Communications, vol. 54, pp. 28–31, May 2015,[5] A. Kola, X. Geng, and E. J. Podlaha, ‘Ag–W electrodeposits with high W content from thiourea–citrate electrolytes’, Journal of Electroanalytical Chemistry, vol. 761, pp. 125–130, Jan. 2016[6] Q. Orecchioni, M-P Gigandet, J-Y Hihn, J Tardelli, ‘Silver-Alloys Electrodeposition for Electrical Conductivities’, submitted to Electrochimica Acta

Effect of Water Networks On Ligand Binding: Computational Predictions vs Experiments.

Rational drug design focuses on the explanation and prediction of complex formation between therapeutic targets and small-molecule ligands. As a third and often overlooked interacting partner, water molecules play a critical role in the thermodynamics of protein-ligand binding, impacting both the entropy and enthalpy components of the binding free energy and by extension, on-target affinity and bioactivity. The community has realized the importance of binding site waters, as evidenced by the number of computational tools to predict the structure and thermodynamics of their networks. However, quantitative experimental characterization of relevant protein-ligand-water systems, and consequently the validation of these modeling methods, remains challenging. Here, we investigated the impact of solvent exchange from light (H2O) to heavy water (D2O) to provide complete thermodynamic profiling of these ternary systems. Utilizing the solvent isotope effects, we gain a deeper understanding of the energetic contributions of various components. Specifically, we conducted isothermal titration calorimetry experiments on trypsin with a series of p-substituted benzamidines, as well as carbonic anhydrase II (CAII) with a series of aromatic sulfonamides. Significant differences in binding enthalpies found between light vs heavy water indicate a substantial role of the binding site water network in protein-ligand binding. Next, we challenged two conceptually distinct modeling methods, the grid-based WaterFLAP and the molecular dynamics-based MobyWat, by predicting and scoring relevant water networks. The predicted water positions accurately reproduce those in available high-resolution X-ray and neutron diffraction structures of the relevant protein-ligand complexes. Estimated energetic contributions of the identified water networks were corroborated by the experimental thermodynamics data. Besides providing a direct validation for the predictive power of these methods, our findings confirmed the importance of considering binding site water networks in computational ligand design.

Challenges and Approaches to Extending the Safe Operational Life of Future Renewable Energy Infrastructure

To decarbonize our economy, a huge network of renewable energy infrastructure will need to be built both onshore and offshore, often at remote locations, to generate and transmit renewable energy, and to convert and store renewable energy. Corrosion and other forms of materials degradation will pose major challenges to critical components of renewable energy infrastructure that often operate in extreme and complex environmental conditions. Currently solar and wind farms are designed only for approximately 25 years due to the degradation of solar panels and wind turbines. Such a short design life is unsustainable, not only from lifecycle assessment point of view, but also for generating significant materials wastage. The lives of batteries, hydrogen electrolysers and fuel cells are also significantly affected by corrosion and materials degradation. Addressing these issues is critical for the feasibility and sustainability of future renewable energy-based economy. Corrosion engineering is expected to play an important role in the emerging renewable energy economy in order to address these issues and challenges. Unfortunately, although substantial progress has been made in corrosion science and engineering over the past decades, major weaknesses exist in the management and control of corrosion of engineering structures exposed to complex engineering environments. This problem becomes even more acute when complex forms of localized corrosion occur on ‘invisible’ and highly variable engineering structures such as underground energy pipelines and offshore wind farms. In most practical cases, the failure of engineering structures is due to unexpected and complex forms of localized damages. The safe service life of an engineering structure is often determined by the ‘worst case scenario’ localized corrosion such as corrosion under disbonded coatings on buried steel pipelines. Effective control and management of localized forms of corrosion in complex environments is probably the most significant issue that has not yet been sufficiently addressed by corrosion engineering. In particular, the prediction, detection and prevention of localized forms of corrosion in complex environments remain the most significant challenges to corrosion engineering.This paper critically reviews the challenges and issues in extending the safe operational life of renewable energy infrastructure in complex environments and discusses potential approaches to overcoming these challenges. It is shown that localized corrosion control is a critical issue that has to be addressed in corrosion science and engineering. Although various approaches to localized corrosion control can be taken in the future to help addressing these issues and challenges, the most practical approach to addressing major challenges of localized corrosion to future renewable energy infrastructure could probably be based on reliable and more effective localised corrosion prediction, detection and control. A prerequisite for achieving such effective and reliable corrosion management is timely knowledge about the initiation, propagation and seriousness of localized corrosion occurring over an engineering structure in order to take timely corrective actions. Currently accurate and reliable localized corrosion prediction in practical engineering structures is very difficult, if not impossible. Current industrial knowledge of localized corrosion is mostly from time based routine inspections using various condition assessment and in-line inspection tools. Although corrosion data from such inspection are useful for identifying longer-term corrosion trends, they often do not have sufficient temporal and spatial resolutions required for predicting dynamic changes in complex localized corrosion including these in renewable energy systems. Acquiring corrosion data more frequently and more reliably is necessary not only for early warning of unanticipated structural failure but also for evaluating the efficiency of corrosion control measures such as cathodic protection, corrosion inhibitors and protective coatings. It is concluded that future corrosion management of renewable energy infrastructure will need to incorporate advanced corrosion monitoring tools, data analytics, artificial intelligence and predictive modelling in order to achieve quantitative, accurate and reliable corrosion prediction and closed-loop smart corrosion control. More specifically, (i) the maintenance and management of future energy infrastructures will require more reliable and accurate corrosion forecast and prediction capabilities for more effective detection, monitoring and control of corrosion on infrastructure exposed to complex and variable environments. (ii) Future energy infrastructure will require more efficient corrosion protection technologies, especially those able to control localized forms of corrosion, in order to extend the service life of future renewable energy infrastructures. (iii) New eco-informed and environmentally friendly anti-corrosion materials and methods will be required to meet progressively strict regulations for environmental protection. Cases are presented from the author’s recent research and development over the past decade.Key references:Y Tan, Heterogeneous Electrode Processes and Localized Corrosion, Wiley (2012)Y M Tan, Localized Corrosion in Complex Environments, Wiley (2023)