Kinetics Of Enzymatic Reaction Research Articles

Kinetic View of Enzyme Catalysis from Enhanced Sampling QM/MM Simulations.

The rate constants of enzyme-catalyzed reactions (kcat) are often approximated from the barrier height of the reactive step. We introduce an enhanced sampling QM/MM approach that directly calculates the kinetics of enzymatic reactions, without introducing the transition-state theory assumptions, and takes into account the dynamical equilibrium between the reactive and non-reactive conformations of the enzyme/substrate complex. Our computed kcat values are in order-of-magnitude agreement with the experimental data for two representative enzymatic reactions.

IMPULSIVE DIFFERENTIAL EQUATION MODEL IN HIV-1 INHIBITION: ADVANCES IN DUAL INHIBITORS OF HIV-1 RT AND IN FOR THE PREVENTION OF HIV-1 REPLICATION

Reverse transcriptase (RT) and integrase (IN) are two pivotal enzymes in HIV-1 replication. RT converts the single-stranded viral RNA genome into double-stranded DNA and IN catalyzes the integration of viral double-stranded DNA into host DNA. Currently, dual inhibitors of HIV-1 RT and IN have become a hotspot in new anti-HIV drug research and development. A dual inhibitor of HIV-1 RT/IN does the same thing as the two independent drugs would do. In this paper, we develop a mathematical model comprising a system of nonlinear differential equations describing HIV-1 RT/IN catalyzed biochemical reactions based on Michaelis–Menten enzyme kinetic reaction. In the formulated model we incorporate HIV-1 RT/IN dual inhibitor which simultaneously works as a non-nucleoside RT inhibitor and IN inhibitor. To examine the efficacy of HIV-1 RT/IN dual inhibitor in the treatment of HIV-1 infection, we have introduced a one-dimensional impulsive differential equation model and determined an effective dosing regimen for applying the inhibitor numerically. Furthermore, the exact closed form solution of the impulsive differential equation model is carried out by using the Lambert W function and the local stability of the periodic solution is also obtained analytically. The results obtained from analytical as well as numerical studies provide a basic idea to investigate the minimum dose with the highest efficacy for administering HIV-1 RT/IN dual inhibitors to prevent HIV-1 infection.

Biomineralization of heavy metals based on urea transport and hydrolysis within a new bacterial isolate, B. intermedia TSBOI

A newly isolated ureolytic bacteria, Brucella intermedia TSBOI, exhibited microbially induced calcite precipitation (MICP) which is a promising technique for the remediation of heavy metals in polluted environments. Brucella intermedia TSBOI achieved 90–100% removal of 1 mmol/L Cu2+/Pb2+/Zn2+ within 72 h. A distinctive feature lies in B. intermedia TSBOI’s capacity for the transport and hydrolysis of urea, considered to be critical for its strong urease activity. This study explored the mechanisms of this capacity at the genetic, molecular and protein levels through complete genome sequencing, molecular docking and enzymatic reaction kinetics. The results revealed that, for urea hydrolysis, B. intermedia TSBOI exhibited a comprehensive urease gene cluster, with the key gene ureC demonstrating an absolute expression level approximating to 4 × 104 copies/RNA ng under optimal conditions. Results also confirmed the strong spontaneous, energy-independent binding ability of it’s urease to urea, with the lowest Gibbs free energy binding site linking to the three amino acids, alanine, asparagine and serine. The urea transport gene yut presented and expressed, with the absolute expression enhanced in response to increasing urea concentrations. The significant positive correlation between ureC/yut expression levels and urease activity provided a theoretical basis for B. intermedia TSBOI's heavy metal bioremediation potential. Environmental ImplicationHeavy metals (Cu, Pb and Zn) were studied in this study. Heavy metals are hazardous due to their toxicity, persistence, and ability to bioaccumulate in living organisms. They can cause severe health issues, harm ecosystems, and contaminate air, water, and soil. A novel ureolytic bacteria, Brucella intermedia TSBOI, exhibited microbially induced carbonate precipitation capability was isolated which removed 90–100% of 1 mmol/L Cu2+/Pb2+/Zn2+ within 72 h. Its advantages in urea hydrolysis and transport facilitate the remediation of actual heavy metal contaminated environments.

Nanoconfined zero-valent iron effectively enhances the catalytic degradation of phenolic pollutants by Fe-Mn bimetallic peroxidase-like compound

Peroxidase mimics can activate H2O2 to degrade organic pollutants in water. A novel bimetallic active center of MOF-based peroxidase-like (POD-like) (Fe@PCN-222(Mn)) was synthesized, with Fe0 uniformly doped within the channels of PCN-222(Mn). This nano-constrained strategy greatly improves the catalytic stability and anti-interference performance of Fe@PCN-222(Mn). Enzymatic reaction kinetics studies showed that Fe0 doping significantly increased the reaction rate. Compared to externally exposed Fe/PCN-222(Mn), pure PCN-222 and PCN-222(Mn), Fe@PCN-222(Mn) exhibited a more stable and efficient performance in the 4-NP-catalyzed degradation process, assisted by both bimetallic synergism and nanoconfinement. Within 60 min, the removal of 4-NP was as high as 100%, while the removal of TOC was 56.74%. The large amount of 1O2 produced in the Fe@PCN-222(Mn)/H2O2 system is the main reason for the rapid degradation of 4-NP. This is because the distance between the pollutant molecules and the ROS is greatly shortened under the nanoconfined conditions, and the electron transfer efficiency between Fe/Mn is also effectively improved. Furthermore, the electronegativity difference between Fe/Mn drives the reaction. This work expands the application of POD-like and offers a new approach to designing and developing Fenton-like catalysts.

OPTIMAL CONTROL ON FRACTIONAL ENZYME KINETICS WITH INHIBITORS

In enzyme kinetic chemical reaction, inhibitors are working as a regulators of the metabolism of the systems and the biochemical activities as well. The main focus of this study is to explore the fractional dynamics of enzyme kinetic biochemical reactions with competitive and uncompetitive inhibitors. Further, the analysis continuous with the optimal controls on the system which accelerate biochemical reactions and maximize product generation. Eventually, the numerical analysis have been done by the Adams predictor–corrector method and the forward–backward sweep method for the dynamics and optimal control study, respectively.

Efficient and fast screening and separation based on computer-aided screening and complex chromatography methods for lipoxygenase inhibitors from Ganoderma lucidum.

Accurate screening and targeted preparative isolation of active substances from natural medicines have long been technical challenges in natural medicine research. This study outlines a new approach for improving the efficiency of natural product preparation, focusing on the rapid and accurate screening of potential active ingredients in Ganoderma lucidum and efficient preparation of lipoxidase inhibitors, with the aim of providing new ideas for the treatment of Alzheimer's disease with G.lucidum. The medicinal plant G.lucidum was selected through ultrafiltration coupled with liquid chromatography and mass spectrometry (UF-LC-MS) and computer-assisted screening for lipoxygenase (LOX) inhibitors. In addition, the inhibitory effect of the active compounds on LOX was studied using enzymatic reaction kinetics, and the underlying mechanism is discussed. Finally, based on the earlier activity screening guidelines, the identified ligands were isolated and purified through complex chromatography (high-speed countercurrent chromatography and semi-preparative high-performance liquid chromatography). Five active ingredients, ganoderic acids A, B, C2 , D2 , and F, were identified and isolated from G.lucidum. We improved the efficiency and purity of active compound preparation using virtual computer screening and enzyme inhibition assays combined with complex chromatography. The innovative methods of UF-LC-MS, computer-aided screening, and complex chromatography provide powerful tools for screening and separating LOX inhibitors from complex matrices and provide a favourable platform for the large-scale production of bioactive substances and nutrients.

Investigating Enzyme-Based Electrode Processes Using Electrochemical Impedance Spectroscopy and Distribution of Relaxation Time Analysis

Enzymatic fuel cells (EFCs) are an emerging class of electrochemical devices that have the potential to harness renewable energy sources by converting the chemical energy of an organic substrate into electrical energy. Enzymes are responsible in an EFC for highly selective and efficient electrode processes under typically mild ambient conditions, such as the oxidation reaction at the anode and the reduction reaction at the cathode 1. In addition to more conventional techniques, electrochemical impedance spectroscopy (EIS) can be employed to characterize such systems. Electrochemical behavior of enzymatic electrodes, such as enzyme reaction kinetics, substrate mass transport, and electrode stability, can be studied by measuring the system's impedance over a wide frequency range and then performing a precise post-process analysis based on the distribution of relaxation time (DRT). DRT analysis is rarely used to interpret EIS spectra within the EFCs research field, despite the fact that it is widely acknowledged as relevant for properly understanding the EIS potential to improve power density in fuel cells 2,3. Glucose oxidase (GOx) and bilirubin oxidase (BOD) were immobilized on multi-walled carbon nanotubes (MWCNTs) to catalyze the bioelectrocatalytic oxidation of glucose at the anode and the bioelectrocatalytic reduction of oxygen at the cathode, respectively. This study presents a promising approach for the investigation of enzyme-based anodic and cathodic processes by measuring them with EIS and then interpreting the results with DRT analysis, as depicted in Figure 1. By varying different operating parameters, such as the enzymatic loading on the electrode surface or electrolyte conditions, this method can be used to identify three primary relaxation processes occurring at both electrodes. At the interface between the electrolyte and the electrode, it is possible to conclude that high-frequency processes are accountable for ionic conduction, intermediate-frequency processes are accountable for charge transfer, and low-frequency processes are accountable for oxygen surface exchange and diffusion.This method provides access to preliminary fundamental information about enzymatic bioelectrode processes, which can be used to optimize biofuel cell construction and compositions and increase their power output. Figure 1. Schematic representation of the characterization method used to characterize a GOx-CNT-modified anode consisting of EIS measurements and subsequent DRT analysis. Concentration of glucose 175 mM in 0.1 M HEPES Buffer, pH 7; EIS parameters: 20 mV sinusoidal excitation, 0.1 Hz-100 kHz. References K. Herkendell, A. Stemmer and R. Tel-Vered, Nano Res., 12(4), 767–775 (2019). H. Wang, X. Long, Y. Sun, D. Wang, Z. Wang, H. Meng, C. Jiang, W. Dong and N. Lu, Frontiers in microbiology, 13, 973501 (2022). F. Ciucci, Current Opinion in Electrochemistry, 13, 132–139 (2019). Figure 1

Methyl oleate for plant protection products formulations: Enzymatic synthesis, reaction kinetics and application testing

This study presents a solvent-free enzymatic approach for the synthesis of fatty acid methyl esters (FAMEs), such as methyl oleate, for their application as adjuvant in plant protection products (PPP) formulations. The direct esterification between free fatty acid and methanol was optimized to achieve 98% acid conversion. The kinetics of this conversion was accurately described by a simple second order mechanism and non-linear regression was applied to calculate the rate constants of the forward and backward reactions based on full progress curves data. The rate constant of the forward reaction (synthesis) was one order of magnitude higher than the backward reaction (hydrolysis) and favored formation of the target methyl ester product, rendering the removal of water unnecessary. Enzymatically synthesized methyl oleate was benchmarked against the chemically synthesized compound, showing matching results in terms of stability, spreadability and emulsifying capacity in plant care formulations. The enzymatic synthesis of FAMEs under solvent free conditions allows to achieve a safer and more sustainable character for carrier solvents in PPP formulations.

Innovative biocatalyst synthesis of pectinolytic enzymes by cross-linking strategy: Potentially immobilised pectinases for the production of pectic-oligosaccharides from pectin

Pectinases are outstanding multienzymes, which have the potential to produce new emerging pectic-oligosaccharides (POS) via enzymatic hydrolysis of pectin. However, free pectinase is unable to undergo repeated reaction for the production of POS. This study proposed a sustainable biocatalyst of pectinases known as cross-linked pectinase aggregates (CLPA). Pectinase from Aspergillus aculeatus was successfully precipitated using 2 mg/mL pectinase and 60 % acetone for 20 min at 20 °C, which remained 36.3 % of its initial activity. The prepared CLPA showed the highest activity recovery (85.0 %), under the optimised conditions (0.3 % (v/v) starch and glutaraldehyde mixture (St/Ga), 1.5: 1 of St/Ga, 25 °C, 1.5 h). Furthermore, pectin-degrading enzymes from various sources were used to produce different CLPA. The alteration of pectinase secondary structure gave high stability in acidic condition (pH 4), thermostability, deactivation energy and half-life, and improved storage stability at 4 °C for 30 days. Similarly to their free counterpart, the CLPA exhibited comparable enzymatic reaction kinetics and could be reused eight times with approximately 20 % of its initial activity. The developed CLPA does not only efficaciously produced POS from pectin as their free form, but also exhibited better operational stability and reusability, making it more suitable for POS production.

The preparation of Diacylglycerol-rich soybean oil by acetylated modification of arachin nanoparticles for W/O Pickering emulsion system.

Pickering emulsion catalytic system (PEC) stabilized by nanoparticles is an efficient catalytic platform. Herein, a high-performance PEC was constructed by acetylated modification of arachin nanoparticles (AAPs). The results showed the pI of arachin was decreased from pH 5.5 to pH 3.5. The surface hydrophobicity index was significantly increased (from 56.28±4.23 to 120.77±0.79) after acetylated modification. The three-phase contact angle of AAPs was 91.20±0.98°. AAPs were used as lipase immobilization carriers to increase the activity of free lipase fabricating lipase-AAPs. The immobilization efficiency and activity of lipase-AAPs were 12.95±0.03% and 1.74±0.07 U/mg, respectively. Enzymatic reaction kinetics showed that Vm of lipase-AAPs was twice of free lipase. Km was 1/5 of free lipase. The catalytic efficiency of PEC to prepare DAG was 2.36 times of biphasic catalytic system (BCS). This work provided a promising way to promote the efficiency of DAG preparation.

In-depth analysis of the acetylcholinesterase inhibitors of Ganoderma amboinense based receptor-ligand affinity coupled with complex chromatography

Given the abundance and intricate nature of the chemical components found in natural food ingredients, functional food research has long grappled with two significant technical challenges: rapid and precise screening of active substances and targeted preparation. This study outlines a novel methodology to enhance the efficiency of preparing natural products, presenting new extraction processes, biological activity screening, and the preparation of acetylcholinesterase inhibitors from Ganoderma amboinense. acetylcholinesterase inhibitors were rapidly screened using ultrafiltration coupled with liquid chromatography and mass spectrometry. The inhibitory effect of active compounds on acetylcholinesterase was investigated via enzymatic reaction kinetics, with the mechanism also explored. Additionally, molecular docking and molecular dynamics simulations were used to verify the anti-alzheimer's disease activity of active compounds. Following this, the biological activity of ligands identified were separated and purified using complex chromatography (consecutive-CCC and semi-preparative HPLC). We used n-hexane: ethyl acetate: methanol: water (4.0:6.0:4.0:6.0, v/v/v/v), which optimized by a universal quasichemical functional group activity coefficient-based mathematical model and semi-preparative HPLC, 25–60% A (0–50 min), 60–100% A (50–60 min). Twelve active ingredients viz. ganoderic acids I, C2, G, B, K, A, D, F, J, ganoderenic acid A, deacetyl ganoderic acid F, and lucidenic acid F with the binding affinity for AChE were identified and isolated from natural foods. We enhance the efficiency and purity of active compounds preparation by incorporating enzyme inhibition assays and computerized virtual screening with compound chromatography. With this approach, we seamlessly incorporate fast discovery, screening, and focused preparation of active ingredients, as well as delving into the mechanisms of action of active monomers and proteases, and the molecular-level interactions between active ingredients and proteases. This approach effectively mitigates the occurrence of false positives attributable to a single technique, thereby providing valuable data to underpin future advances in enzyme inhibitor screening and isolation.

Rapid screening, isolation, and activity evaluation of potential xanthine oxidase inhibitors in Polyporus umbellatus and mechanism of action in the treatment of gout.

Studies show that Polyporus umbellatus has some pharmacological effects in enhancing immunity and against gout. We aimed to establish new techniques for extraction, biological activity screening, and preparation of xanthine oxidase inhibitors (XODIs) from P.umbellatus. First, the extraction of P.umbellatus was investigated using the back propagation (BP) neural network genetic algorithm mathematical regression model, and the extraction variables were optimised to maximise P.umbellatus yield. Second, XODIs were rapidly screened using ultrafiltration, and the change of XOD activity was tested by enzymatic reaction kinetics experiment to reflect the inhibitory effect of active compounds on XOD. Meanwhile, the potential anti-gout effects of the obtained active substances were verified using molecular docking, molecular dynamics simulations, and network pharmacology analysis. Finally, with activity screening as guide, a high-speed countercurrent chromatography (HSCCC) method combined with consecutive injection and two-phase solvent system preparation using the UNIFAC mathematical model was successfully developed for separation and purification of XODIs, and the XODIs were identified using MS and NMR. The results verified that polyporusterone A, polyporusterone B, ergosta-4,6,8(14),22-tetraen-3-one, and ergosta-7,22-dien-3-one of P.umbellatus exhibited high biological affinity towards XOD. Their structures have been further identified by NMR, indicating that the method is effective and applicable for rapid screening and identification of XODIs. This study provides new ideas for the search for natural XODIs active ingredients, and the study provide valuable support for the further development of functional foods with potential therapeutic benefits.

Long Short-Term Memory-Based Multiomics Reveal Lactobacillus casei-Derived Postbiotics Inhibiting Lipids Digestion via Mediating the Upregulation of α-Helices in Lipase.

The antiobesity function of probiotics has been declared, while the application in high-risk patients and coding side effect has focused attention to postbiotics. This investigation profiles the mechanism of postbiotics affecting lipid digestion at molecular level, and establishes a momentous foundation for the clinical application of postbiotics in obesity suppression. An operational framework for butter digestion is constructed to collect the digests in the intestine at 0, 40, 80, and 120min with various postbiotics supplement. A total of 227 lipids and 414 metabolites are detected by pseudo-targeted lipidomics integrated with the long short-term memory-based metabolomics, and the triacylglycerol (TG, from 134.1 to 184.7mg kg-1 ) and diacylglycerol (DG, from 4.2 to 8.4mgkg-1 ) are identified as significantly different lipids with or without postbiotics supplement. A total of eight substances related to the inhibition of gastric lipase and pancreatic lipase are screened through the molecular simulation computation in silicon and enzymatic reaction kinetics, and thus curtailing the bioaccessibility of lipids. Lactobacillus casei JCM1134-derived postbiotics propel the structure of lipase to aggregate by increasing the α-helix, and thus hampering the digestion of triglycerides through noncompetitive inhibition.

Approximation of intra-particle reaction/diffusion effects of immobilized enzyme system following reverse Michaelis–Menten (rMM) mechanism: third degree polynomial and Akbari–Ganji methods

Two approximate analytical expressions based on third degree polynomial and Akbari–Ganji’s method (AGM) were derived for the reaction/diffusion controlled kinetics of an immobilized enzyme (IE) systems. The approximation methods predict substrate concentration profile and effectiveness factor (eta) in a porous spherical particle. The reaction is assumed to follow reverse Michaelis–Menten (rMM) kinetics. The approximate methods predictions were comparable to that of numerical solution (using the Matlab finite difference function, bvp4c) at wide range of {phi }^{2} and {y}_{o} especially at low {phi }^{2} and high {y}_{o} (polynomial equation) and low {phi }^{2} and low {y}_{o} (AGM equation). Although the approximate solution was derived for rMM kinetics, the results can be used to describe other important enzymatic reaction kinetics such as simple Michaelis–Menten (MM) kinetics and MM with competitive product inhibition kinetics. A necessary design equation should be satisfied when using polynomial or AGM approximation for different enzyme kinetic equations. In this work, two examples of enzymatic reactions of industrial interest were studied, namely glucose-fructose isomerization follows rMM kinetics and hydrolysis of lactose follows Michaelis–Menten (MM) equation with competitive product (galactose) inhibition. Predictions of the developed third degree polynomial and AGM approximation equations agree with that of numerical solution, the percentage relative error for the effectiveness factor was less than 11 in comparison with the numerical solution. Good agreement between approximate and numerical estimations demonstrates the validity of these approximation methods.

Straw, biochar, and nanocarbon altered the enzymatic reaction kinetics and thermodynamic process of catalase in the black soil under continuous warming

ABSTRACT Different C influences the kinetic and thermodynamic behavior of catalase (CAT) remains unknown. The study aimed to assess the impact of three different C [straw, biochar, nanocarbon] on kinetic and thermodynamic characteristic of CAT in 5 °C ~ 45 °C. These three C-sources increased Vmax, Vmax/Km, and decreased Km, ΔG, ΔH, ΔS at different temperatures. The addition of nanocarbon induced significant changes in the soil enzymatic characteristics, resulting in the highest soil CAT-activity. After continuous-heating, the addition of three C-sources to the soil increased and then decreased the CAT-activity and its kinetic parameters and their values peaked at 15 °C or 25 °C. On the other hand, the ΔG showed decreasing and then increasing trend and ΔS gradually increased. Q 10 decreased and correlations between CAT and kinetic thermodynamic parameters were observed with increasing-temperature in three C-treatments. There was a significant correlation between soil’s physicochemical properties and soil CAT-activity and their enzymatic reaction characteristics after straw and biochar-treatments. However, an insignificant correlation was observed between the soil indexes after the nanocarbon-treatment. Thus, different C-sources could increase the soil CAT-activity by promoting the enzymatic reaction process under continuous-warming. The continues-warming without any change in the temperature-adaptation of CAT, but its temperature-sensitivity decreased after C-source addition.

Reversible and Non-Competitive Inhibition of Cyclooxygenase by Indobufen for Efficient Antiplatelet Action and Relief of Gastrointestinal Irritation.

Clinically, indobufen is widely used for the treatment of antiplatelet aggregation and anticoagulation. Prior studies have discovered that abnormal platelet function can be promptly restored to normal when the drug is stopped. Herein, through the study of the enzyme reaction kinetics, we demonstrated that the inhibitory effect of indobufen on cyclooxygenase-1 (COX-1) was reversible and non-competitive. Specifically, the cyclooxygenase inhibition experiment showed that the level of 6-keto-PGF1α in the gastric mucosa of the indobufen-treated groups was significantly higher than that of the aspirin group (###p < 0.001), indicating a higher level of PGI2 in and a better physiological state of the gastric mucosa. Moreover, the rat gastric ulcer index and mucosal section experiments further confirmed the relief of gastrointestinal irritation and the adverse reaction rate of the indobufen-treated group compared to those of the aspirin group. Furthermore, indobufen was verified to exert reversible inhibitory activity on the heme group of COX-1 and thus reversibly inhibit COX-1 activity. In general, compared with aspirin, the long-term oral administration of indobufen yields a lower risk of gastrointestinal symptoms, such as ulcers.

In-depth analysis of the xanthine oxidase inhibitors of Cicer arietinum L.-based receptor-ligand affinity coupled with complex chromatography.

Cicer arietinum L. is the choice of health food for people with diabetes, hypertension, and hyperlipidemia. As an essential source of high-nutrition legumes, it is also an important source of dietary isoflavones. In order to improve the preparation efficiency of natural plants, a rapid biological activity screening and preparation of xanthine oxidase inhibitors from C. arietinum L. was established. Xanthine oxidase (XOD) inhibitors were rapidly screened using ultrafiltration liquid chromatography-mass spectrometry (UF-LC-MS) based on receptor-ligand affinity. The change in XOD activity was evaluated by enzymatic reaction kinetics measurement. The potential bioactive compounds were verified through molecular docking. In addition, the biological activity of ligands screened was separated and purified by complex chromatography. The structures of the compounds were identified by nuclear magnetic resonance spectroscopy. Three active ingredients, namely daidzin, daidzein, calycosin with XOD binding affinities were identified and isolated from the raw plant materials via semi-preparative high-performance liquid chromatography (HPLC), 0-60 min, 5-50% B and countercurrent chromatography (CCC) (ethyl acetate/acetic acid/water [5:0.8:10, v/v/v]). This study will help to elucidate the mechanisms of action of natural plants of interest at the molecular level and could also provide more opportunities for the discovery and development of new nutritional value from other natural resources.

Detection and treatment of biofilm-induced periodontitis by histidine-doped FeSN nanozyme with ultra-high peroxidase-like activity

Pathogenic biofilm induced oral diseases have posed a significant treat to human health, such as periodontitis resulting from the formation of bacterial biofilm on teeth and gums. The traditional treatment methods such as mechanical debridement and antibiotic therapy encounter the poor therapeutic effect. Recently, numerous nanozymes with excellent antibacterial effect have been widely used in the treatment of oral diseases. In this study, a novel iron-based nanozyme (FeSN) generated by histidine-doped FeS2 with high peroxidase-like (POD-like) activity was designed for the oral biofilm removal and treatment of periodontitis. FeSN exhibited an extremely high POD-like activity, and enzymatic reaction kinetics and theoretical calculations had demonstrated its catalytic efficiency to be approximately 30 times than that of FeS2. The antibacterial experiments showed that FeSN had robust antibacterial activity against Fusobacterium nucleatum in the presence of H2O2, causing a reduction in the levels of glutathione reductase and ATP in bacterial cells, while increasing the level of oxidase coenzyme. The ultrahigh POD-like activity of FeSN allowed for easy detection of pathogenic biofilms and promoted the breakdown of biofilm structure. Furthermore, FeSN demonstrated excellent biocompatibility and low cytotoxicity to human fibroblast cells. In a rat model of periodontitis, FeSN exhibited significant therapeutic effects by reducing the extent of biofilm formation, inflammation, and alveolar bone loss. Taken together, our results suggested that FeSN, generated by self-assembly of two amino acids, represented a promising approach for biofilm removal and periodontitis treatment. This method has the potential to overcome the limitations of current treatments and provide an effective alternative for periodontitis treatment.

Engineering a Hollow Carbon Sphere-Based Triphase Microenvironment for Enhanced Enzymatic Reaction Kinetics and Bioassay Performance.

Electrochemical bioassays based on oxidase reactions are frequently used in biological sciences and medical industries. However, the enzymatic reaction kinetics are severely restricted by the poor solubility and slow diffusion rate of oxygen in conventional solid-liquid diphase reaction systems, which inevitably compromises the detection accuracy, linearity, and reliability of the oxidase-based bioassay. Herein, an effective solid-liquid-air triphase bioassay system is provided that uses hydrophobic hollow carbon spheres (HCSs) as oxygen nanocarriers. The oxygen stored in the cavity of HCS can rapidly diffuse to the oxidase active sites through the mesoporous carbon shell, providing sufficient oxygen for oxidase-based enzymatic reactions. As a result, the triphase system can significantly improve the enzymatic reaction kinetics and obtain a 20-fold higher linear detection range than the normal diphase system. Other biomolecules can also be determined using this triphase technique, and the triphase design strategy offers a new route to address the gas deficiency problem in catalytic reactions that involve gas consumption.

High-performance self-powered photoelectrochemical bioassay system with a triphase oxidase enzymatic interface

In the field of biomolecule detection, self-powered photoelectrochemical (PEC) bioassay devices have gained considerable interest with no demand for an external voltage but rather solar energy consumption. In this study, we present a self-powered PEC bioassay system that consists of a nanoporous BiVO4 photoanode coupled to a biophotocathode with a solidliquidair triphase oxidase enzymatic interface. The triphase biophotocathode was assembled by immobilizing oxidase on superhydrophobic Cu2O@TiO2 nanowire arrays. A high and steady interfacial oxygen concentration can be ensured by the triphase biophotocathode with much increased gas mass transport capability, which consequently enhance the kinetics of the oxidase enzymatic reaction as well as the sensing performance of self-powered PEC bioassay system. For the diphase biophotocathode based system, the low solubility and slow diffusion rate of oxygen restrict the kinetics of the oxidase catalytic reaction. As a result, the proposed triphase self-powered PEC bioassay platform exhibits excellent performance with a linear range up to 20 mM for glucose (a model analyst) detection, which is 20 times higher than that of the diphase one. Furthermore, an exceptional anti-interface is obtained by the cathodic bioanalysis approach in the self-powered PEC bioassay system.