Glucose Oxidation Research Articles

A sandwich-type dual-mode biosensor based on graphdiyne and DNA nanoframework for ultra-sensitive detection of CD142 gene

Thalassemia is a globally prevalent single-gene blood disorder, with nearly 7% of the world's population being carriers. Therefore, the development of specific and sensitive methods for thalassemia detection holds significant importance. Herein, a sandwich-type electrochemical/colorimetric dual-mode biosensor is developed based on gold nanoparticles (AuNPs)/graphdiyne (GDY) and DNA nanoframeworks for ultra-sensitive detection of CD142 gene associated with sickle cell anemia. Utilizing AuNPs/GDY as the substrate electrode, the fabricated sandwiched DNA nanoframework not only improves selectivity but also introduces numerous signal probes to further amplify the output signal. In the electrochemical mode, glucose oxidase catalyzes the oxidation of glucose, generating electrons that are transferred to the biocathode for a reduction reaction, resulting in an electric signal proportional to the target concentration. In the colorimetric mode, glucose oxidase catalyzes the generation of H2O2 from glucose, and with the aid of horseradish peroxidase, H2O2 oxidizes 3,3′,5,5′-tetramethylbenzidine to produce a colored product, enabling colorimetric detection of the target. The dual-mode biosensor demonstrates a detection range of 0.0001–100 pM in the electrochemical mode and a detection range of 0.0001–10,000 pM in the colorimetric mode. The detection limit in the electrochemical mode is determined to be 30.4 aM (S/N=3), while in the colorimetric mode is of 35.6 aM (S/N=3). This dual-mode detection achieves ultra-sensitive detection of CD142, demonstrating broad prospects for application.

(Invited) Nickel Nanoparticles Modified Carbon Film Electrodes for Detection of Sugars

Metal nanoparticles such as Pt, Au, Ni and Cu have been employed to detect various analytes including hydrogen peroxide, alcohol and sugar. Among these metal nanoparticles, Ni and Cu nanoparticles show excellent electrocatalytic activity for oxidizing sugars in alkaline solution. We employed co-sputtering and plating technique to fabricate nanostructured electrodes for enhancing electrocatalytic activity for oxidation of sugars. First example is a metal hererodimer modified carbon film electrodes. The metal nanoparticles embedded carbon film electrodes was fabricated by unbalanced magnetron (UBM) sputtering and then plated different metal nanoparticles selectively only on the embedded metal nanoparticles by utilizing overpotential difference between carbon and metal nanoparticles surfaces. Using this technique, various combinations of metals are available to fabricate vertically oriented heterodimers embedded in the carbon films. In fact, we succeeded to fabricated Ni(upper)@Pd(lower), Pt@Pd, Au@Pd, Ni@Au, Pt@Au and Pd@Au heterodimers partially embedded in the carbon film. Among these heterodimers, Ni@Pd heterodimer embedded carbon film electrode shows much higher redox reaction of Ni(OH)2 covered on the Ni nanoparticles surface compared with that on the Ni nanoparticles without Pd. The NiOOH formed by electrochemical oxidation shows much higher electrocatalytic activity for glucose compared with that formed on Ni nanoparticles modified carbon film electrode. Also, the Ni@Pd heterodimers are mechanically very stable and most of the heterodimers remained on the surface after ultrasonication treatment because surface Ni nanoparticles attached strongly to Pd nanoparticles embedded in the carbon film. In contrast, almost all Ni nanoparticles deposited on pure carbon film were detached from carbon surface after ultrasonication. The second example is a nitrogen terminated carbon film modified with Ni nanoparticles by plating. Carbon films were fabricated by UBM or RF sputtering methods and then introduced nitrogen containing functional groups. Then Ni nanoparticles were deposited by plating. The supporting effect of a N-doped carbon film induced superior crystallinity in plated Ni@Ni(OH)2 nanoparticles, which was confirmed by HAADF-STEM-EDS. This realized a much higher regeneration rate of catalytic sites (NiOOH) , leading to higher oxidation current for maltopentaose, which is well known oligosaccharide. Also, the overpotential of maltopentaose oxidation decreased significantly due to the effect of the electrostatic interaction between Ni nanoparticles and maltopentaose in the alkaline solution at pH 12.7. We also studied dependence of nitrogen concentration in the carbon film on regeneration rate of NiOOH and glucose oxidation. Both regeneration rate and electrocatalytic current of glucose oxidation increased with increasing nitrogen concentration from 0 to 3.1 %. With optimized nitrogen concentration, we could measure glucose from 25 µM to 400 µM. The enhanced activity of Ni nanoparticles could be advantageous to develop enzyme free biosensor or fuel cells using organic compounds such as sugars and oligosaccharides.[1]S. Shiba, A. Koike, S. Takahashi, D. Kato, T. Kamata and O. Niwa, ACS Nano, 16, 10589-10599 (2022).[2] S. Shiba, S. Ohta, K. Ohtani, S. Takahashi, D. Kato and O. Niwa, RSC Advances, 11, 13311-13315 (2021).

Electrocatalytic Conversion of Glucose into Hydrogen and Value-Added Compounds on Gold and Nickel Catalysts

Fine chemistry historically relies on the fossil fuel industry, implying oil extraction and refining [1]. The rarefaction of this resource and adverse environmental consequences of its extraction motivate research for alternative sources of chemicals. Low carbon footprint chemicals can be synthesized from nonedible biomass waste [2]; cellulose extracted from biomass can therefore play an important role, being a clean and widely accessible carbon source. One can extract D-Glucose (units that constitute cellulose) from cellulose and obtain numerous chemicals of interest, such as sorbitol [3][4] or gluconic acid [5][6] (gluconate in alkaline media), respectively by selective reduction or oxidation.Searching for high-performance non-enzymatic catalysts to perform such reactions brought us to study the activity and selectivity of gold and nickel in alkaline media. At the anode, results from differential electrochemical mass spectrometry (DEMS) seem to indicate that the glucose oxidation on a gold surface initiates by its dissociative adsorption (dehydrogenation): the dihydrogen (H2) produced likely originates from the formation of metastable H adsorbates (Had) [7] that diffuse onto the surface [8] and recombine into H2. In parallel, the adsorbed glucose oxidizes into value-added products such as gluconic acid, through a mechanism proposed from in situ (Fourier Transform InfraRed spectroscopy, FTIR) and ex situ (products analysis by High Performance Liquid Chromatography, HPLC) observations, and on the evaluation of the number of exchanged electrons using the rotating ring disk electrode (RRDE). Confronting the experimental data to a microkinetics model enables to validate the proposed mechanism and to estimate the kinetics rate constants. At the cathode, the glucose reduction reaction (GRR) into sorbitol competes with the hydrogen evolution reaction (HER). The HER activity of nickel strongly depends on its surface oxidation state [9], which can be tuned to search the best selectivity towards sorbitol. Combining high value-added compounds production with H2 as by-product allows to improve the overall energy efficiency of this electrolysis.[1] P. G. Levi and J. M. Cullen, “Mapping global flows of chemicals: from fossil fuel feedstocks to chemical products,” Environ. Sci. Technol., vol. 52, no. 4, pp. 1725–1734, 2018, doi: 10.1021/acs.est.7b04573.[2] D. Saygin, D. J. Gielen, M. Draeck, E. Worrell, and M. K. Patel, “Assessment of the technical and economic potentials of biomass use for the production of steam, chemicals and polymers,” Renew. Sustain. Energy Rev., vol. 40, pp. 1153–1167, 2014, doi: 10.1016/j.rser.2014.07.114.[3] B. García, J. Moreno, G. Morales, J. A. Melero, and J. Iglesias, “Production of sorbitol via catalytic transfer hydrogenation of glucose,” Appl. Sci., vol. 10, no. 5, 2020, doi: 10.3390/app10051843.[4] X. Guo et al., “Selective hydrogenation of D-glucose to D-sorbitol over Ru/ZSM-5 catalysts,” Chinese J. Catal., vol. 35, no. 5, pp. 733–740, May 2014, doi: 10.1016/S1872-2067(14)60077-2.[5] H. S. Isbell, H. L. Frush, and F. J. Bates, “Manufacture of calcium gluconate by electrolytic oxidation of dextrose,” Ind. Eng. Chem., vol. 24, no. 4, pp. 375–378, 1932, doi: 10.1021/ie50268a003.[6] S. Anastassiadis and I. Morgunov, “Gluconic acid production,” Recent Pat. Biotechnol., vol. 1, no. 2, pp. 167–180, May 2007, doi: 10.2174/187220807780809472.[7] M. M. Jaksic, B. Johansen, and R. Tunold, “Electrochemical behaviour of gold in acidic and alkaline solutions of heavy and regular water,” Int. J. Hydrogen Energy, vol. 18, no. 2, pp. 91–110, Feb. 1993, doi: 10.1016/0360-3199(93)90196-H.[8] J. Cornejo-Romero, A. Solis-Garcia, S. M. Vega-Diaz, and J. C. Fierro-Gonzalez, “Reverse hydrogen spillover during ethanol dehydrogenation on TiO2-supported gold catalysts,” Mol. Catal., vol. 433, pp. 391–402, 2017, doi: 10.1016/j.mcat.2017.02.041.[9] A. G. Oshchepkov et al., “Nanostructured nickel nanoparticles supported on vulcan carbon as a highly active catalyst for the hydrogen oxidation reaction in alkaline media,” J. Power Sources, vol. 402, no. June, pp. 447–452, 2018, doi: 10.1016/j.jpowsour.2018.09.051. Figure 1

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

Nonenzymatic Glucose Sensor Using Bimetallic Catalysts.

Bimetallic glucose oxidation electrocatalysts were synthesized by two electrochemical reduction reactions carried out in series onto a titanium electrode. Nickel was deposited in the first synthesis stage followed by either silver or copper in the second stage to form Ag@Ni and Cu@Ni bimetallic structures. The chemical composition, crystal structure, and morphology of the resulting metal coating of the titanium electrode were investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electron microscopy. The electrocatalytic performance of the coated titanium electrodes toward glucose oxidation was probed using cyclic voltammetry and amperometry. It was found that the unique high surface area bimetallic structures have superior electrocatalytic activity compared to nickel alone. The resulting catalyst-coated titanium electrode served as a nonenzymatic glucose sensor with high sensitivity and low limit of detection for glucose. The Cu@Ni catalyst enables accurate measurement of glucose over the concentration range of 0.2-12 mM, which includes the full normal human blood glucose range, with the maximum level extending high enough to encompass warning levels for prediabetic and diabetic conditions. The sensors were also found to perform well in the presence of several chemical compounds found in human blood known to interfere with nonenzymatic sensors.

IMPACT OF MELATONIN ON SOME INDICATORS OF CARBOHYDRATE METABOLISM IN LIVER OF RATS WITH DEXAMETHASONE-INDUCED DIABETES

One frequently employed experimental model, particularly in pre-clinical studies examining the hypoglycemic effects of potential antidiabetic medications, is the metasteroid diabetes model induced by the prolonged administration of glucocorticoids to animals. This experimental study aimed to elucidate the effects of exogenous melatonin (10 mg/kg) on glycogen content and the activity of key enzymes—pyruvate kinase (PK) [EC 2.7.1.40], lactate dehydrogenase (LDH) [EC 1.1.1.27], glucose-6-phosphate dehydrogenase (G-6-PDH) [EC 1.1.1.49], and glucose-6-phosphatase (G-6-P-ase) [EC 3.1.3.9]—in the livers of rats with dexamethasone-induced diabetes. Materials and Methods. The experiments were performed on 44 male 18-month-old white non-linear rats, divided into three groups: 1) control (intact rats), 2) rats with dexamethasone-induced diabetes, 3) rats that amid the progression of dexamethasone-induced diabetes, underwent daily oral administration of melatonin (Sigma, USA) in a dose of 10 mg/kg. Dexamethasone diabetes was modeled by subcutaneous injection of dexamethasone (injection solution 4 mg/ml, KRKA, Slovenia) at a dose of 0.125 mg/kg body weight daily for 13 days (O.V. Stefanov, 2001). Decapitation of animals was carried out in accordance with the norms of the "European Convention for the Protection of Vertebrate Animals Used for Experimental and Other Scientific Purposes" (Strasbourg, 1986). Glucose content in blood from the tail vein of rats, taken on the 14th day of fasting before decapitation of the animals, was determined using a portable glucometer (One Touch Ultra Easy, Life Scan, USA). The content of glycogen and the activity of the studied enzymes of carbohydrate metabolism in the liver were determined according to the generally accepted, previously described methods. A 5% homogenate was prepared from the cold-isolated rat liver in a chilled 50 mM Tris-HCI buffer (pH=7.4) to study the activities of pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase and glucose-6-phosphatase in the cytosolic fraction. The reliability of the difference between the obtained indicators was assessed using the parametric Student's t-test (for normal distribution) and the non-parametric Mann-Whitney U-test (for non-normal distribution). Differences were considered probable at p≤0.05. Results and discussion. According to our results, in the liver of diabetic rats that did not receive any means of correction of carbohydrate metabolism disorders, the glycogen content was 33% lower than in intact animals. The activities of enzymes such as pyruvate kinase and glucose-6-phosphate dehydrogenase were also reduced in the liver of rats with impaired glucose tolerance by 31.6 and 21.5%, respectively, compared to intact animals, indicating inhibition of glucose oxidation pathways, both at the level glycolysis (decrease of pyruvate kinase), as well as at the level of the oxidative stage of the pentose-phosphate pathway of glucose-6-phosphate oxidation. At the same time, the activity of lactate dehydrogenase and especially glucose-6-phosphatase in the liver of rats with diabetes by 19.5 and 56%, respectively, exceeded the indicators of animals of the control group, which demonstrates the increased activity, intensity of glycogenolysis and gluconeogenesis under conditions of insulin resistance, because glucose-6-phosphatase is the terminal enzyme of these processes. Regarding the investigated parameters of carbohydrate metabolism, both the glucose content in the blood of rats, as well as the glycogen content and the activity of all studied enzymes in the liver of rats that were injected with melatonin against the background of the development of diabetes, did not reliably differ from the parameters of intact animals, which confirms the assumption of the probable hypoglycemic effect of melatonin against the background of the development of diabetes. Conclusions: The daily two-week use of melatonin (10 mg/kg), against the background of the development of dexamethasone diabetes in rats, contributes to the normalization of certain indicators of carbohydrate metabolism in the liver of animals.

Synthesis of a Multifunctional Glyco-Block Copolymer through Reversible Addition-Fragmentation Chain Transfer Polymerization and Click Chemistry for Enzyme and Drug Loading into MDA-MB-231 Cells.

Reversible addition-fragmentation chain transfer polymerization has been used in various applications such as preparing nanoparticles, stimulus-responsive polymers, and hydrogels. In this study, the combination of this polymerization method and Cu(I)-catalyzed azide-alkyne cycloaddition click chemistry was used to prepare the multifunctional glyco-diblock copolymer P(PEG-co-AM)-b-PF, which is composed of mannosides for cell targeting, poly(ethylene glycol) (PEG) for biocompatibility, and aryl-aldehyde moieties for enzyme immobilization. The alkyne group in the polymer structure enables the alternation for other azide-conjugated monomers. The stepwise synthesis of the polymers was fully characterized. P(PEG-co-AM)-b-PF was self-assembled into polymeric nanoparticles (BDOX-GOx@NPs) for glucose oxidase immobilization through Schiff base formation and for encapsulating the prodrug of arylboronate-linked doxorubicin (BA-DOX) under optimal conditions. Glucose oxidase in BDOX-GOx@NPs catalyzes glucose oxidation to produce gluconic acid and H2O2, which cause oxidative stress. Glucose oxidase also consumes glucose, causing starvation in cancer cells. The produced H2O2 can selectively activate the anticancer prodrug BA-DOX for chemotherapy. In vitro data indicate that GOx and the prodrug BA-DOX present inside BDOX-GOx@NPs exhibit higher stability than free glucose oxidase with a favorable active DOX release profile. MDA-MB-231 cells, which express mannose receptors, were used to establish a model in this study. The bioactivity of the nanoplatform in the two- and three-dimensional models of MDA-MB-231 cancer cells was investigated to ascertain its antitumor efficacy.

Dual-path glucose electrooxidation reaction on Ni(OH)2/NiOOH catalysts in alkaline media

Glucose electrooxidation has been widely studied for its application in biosensors, fuel cells and electrosynthesis of value-added products. Nickel is known to catalyze the glucose oxidation reaction (GOR) in alkaline media, but the mechanism, the nature of the active sites, and reaction products are still being debated. This study focuses on elucidating the reaction pathways of the GOR on a Ni(OH)2/NiOOH electrode through electrochemical measurements, in-situ Fourier transform infrared spectroscopy (FTIRS) and microkinetic modeling. The electrode was prepared by Ni electrodeposition on glassy carbon (NiED/GC) followed by electrochemical oxidation into Ni(OH)2/NiOOH. The shape of the cyclic voltammograms obtained during the GOR was found to be significantly influenced by the presence of Fe impurities in the NaOH electrolyte. With the help of microkinetic modeling, a dual-path mechanism was proposed for the glucose electrooxidation on the Ni(OH)2/NiOOH surface, comprised of Eley–Rideal and Langmuir-Hinshelwood pathways, with NiOOH reacting either with glucose from solution or adsorbed on Ni(OH)2 sites. In-situ FTIR measurements reveal the formation of formate at potentials as low as 1.17 V vs. RHE.

Swellable colorimetric microneedles for glucose detection based on glucose oxidase-like gold nanoparticles

BackgroundRegular blood glucose monitoring is very important for diabetic patients. The composition of skin interstitial fluid (ISF) is similar to that of blood, which can be used for daily blood sugar detection and disease care. However, most methods of ISF extraction have complicated steps, may cause skin damage, and can only extract a limited amount of ISF, resulting in low detection efficiency. Therefore, it is very necessary to develop a detection method that can not only extract a large amount of ISF safely, efficiently, and conveniently, but also realize rapid detection of glucose level in ISF. ResultsHere, we developed a gold nanoparticle (AuNP)-based swellable colorimetric MN patch with minimally invasive sampling function and real-time ISF glucose analysis ability. The MN patch could quickly absorb a large amount of skin ISF, and 60.2 mg of ISF was extracted within 10 min in vitro. It was divided into two layers: the tip layer was embedded with AuNPs with glucose oxidase (GOx)-like activity, which catalyzed the oxidation of glucose extracted from ISF and produced hydrogen peroxide (H2O2); horseradish peroxidase (HRP) encapsulated in the backing layer catalyzed the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) by H2O2 to produce oxTMB, which led to a visible color shift in the backing layer. The ISF glucose level was judged by naked eyes and further quantified by color analysis with Image J software. As a result, the colorimetric MN patch successfully identified the normal blood sugar and hyperglycemia state in vivo. SignificanceThe colorimetric MN patch combined in-situ colorimetric sensing based on AuNP nanozyme with MN patch, which detected glucose level without blood drawing, increasing patients’ compliance and reducing detection steps and time. Compared with the detection methods based on natural nanozymes, our method had better stability and sensitivity to complex environments (extreme pH and high temperature, etc.) in actual detection.

Altered carbohydrate oxidation during exercise in overreached endurance athletes is applicable to training monitoring with continuous glucose monitors.

The purpose of the study was to investigate whether carbohydrate utilization is altered during exercise in overreached endurance athletes and examine the utility of continuous glucose monitors (CGM) to detect overreaching status. Eleven endurance athletes (M:8, F:3) completed a 5-week training block consisting of 1 week of reduced training (PRE), 3 weeks of high-intensity overload training (POST), and 1 week of recovery training (REC). Participants completed a Lamberts and Lambert Submaximal Cycling Test (LSCT) and 5 km time-trial at PRE, POST, and REC time points, 15 min following the ingestion of a 50 g glucose beverage with glucose recorded each minute via CGM. Performance in the 5 km time-trial was reduced at POST (∆-7 ± 10 W, p = 0.04, = 0.35) and improved at REC (∆12 ± 9 W from PRE, p = 0.01, = 0.66), with reductions in peak lactate (∆-3.0 ± 2.0 mmol/L, p = 0.001, = 0.71), peak HR (∆-6 ± 3 bpm, p < 0.001, = 0.86), and Hooper-Mackinnon well-being scores (∆10 ± 5 a.u., p < 0.001, = 0.79), indicating athletes were functionally overreached. The respiratory exchange ratio was suppressed at POST relative to REC during the 60% (POST: 0.80 ± 0.05, REC: 0.87 ± 0.05, p < 0.001, = 0.74), and 80% (POST: 0.93 ± 0.05, REC: 1.00 ± 0.05, p = 0.003, = 0.68) of HR-matched submaximal stages of the LSCT. CGM glucose was reduced during HR-matched submaximal exercise in the LSCT at POST (p = 0.047, = 0.36), but not the 5 km time-trial (p = 0.07, = 0.28) in overreached athletes. This preliminary investigation demonstrates a reduction in CGM-derived glucose and carbohydrate oxidation during submaximal exercise in overreached athletes. The use of CGM during submaximal exercise following standardized nutrition could be employed as a monitoring tool to detect overreaching in endurance athletes.

Photocatalytic fenton-like system with atomic Fe on carbon nitride boost selective glucose oxidation towards gluconic acid

Peroxymonosulfate (PMS) activation is a prospective technique for pollutant degradation, but less attention has been paid to the tunable modulation and effective utilization of reactive oxygen species in selective oxidation. Herein, we develop a photocatalytic Fenton-like system with Fe single-atom supported on carbon nitride that generates singlet oxygen (1O2) as dominant active species to selectively oxidize glucose to gluconic acid. The loading of atomic Fe onto carbon nitride can notably aggrandize the light absorption and boost the photon-generated carriers transfer efficiency. With PMS and simulated sunlight, the Fe single-atom catalyst afforded a glucose conversion of 36.3% with gluconic acid selectivity up to 91.6%, as is superior to the state-of-the-art catalytic systems. Control experiments and theoretical analysis reveal that the excellent catalytic performance of Fe single-atom supported on carbon nitride is resulted from the enhanced photocatalytic activity with better PMS activation ability.

Dexmedetomidine post-treatment exacerbates metabolic disturbances in septic cardiomyopathy via α2A-adrenoceptor

Cardiomyopathy is a common complication and significantly increases the risk of death in septic patients. Our previous study demonstrated that post-treatment with dexmedetomidine (DEX) aggravates septic cardiomyopathy. However, the mechanisms for the side effect of DEX post-treatment on septic cardiomyopathy are not well-defined. Here we employed a cecal ligation and puncture (CLP) model and α2A-adrenoceptor deficient (Adra2a-/-) mice to observe the effects of DEX post-treatment on myocardial metabolic disturbances in sepsis. CLP mice displayed significant cardiac dysfunction, altered mitochondrial dynamics, reduced cardiac lipid and glucose uptake, impaired fatty acid and glucose oxidation, enhanced glycolysis and decreased ATP production in the myocardium, almost all of which were dramatically enhanced by DEX post-treatment in septic mice. In Adra2a-/- mice, DEX post-treatment did not affect cardiac dysfunction and metabolic disruptions in CLP-induced sepsis. Additionally, Adra2a-/- mice exhibited impaired cardiac function, damaged myocardial mitochondrial structures, and disturbed fatty acid metabolism and glucose oxidation. In sum, DEX post-treatment exacerbates metabolic disturbances in septic cardiomyopathy in a α2A-adrenoceptor dependent manner.

An island-like Re-containing phytate bimetal nanocluster catalyst for exceptional overall glucose electrolysis hydrogen production

In this paper, an island-like Re-containing phytate bimetal nanocluster catalyst was uniformly prepared on nickel foam by the chemical induced deposition@self-assembly method. The existence of valence-enriched Re and hydrophilic phytate molecules will improve the active area, charge transfer rate, and wetting ability of the intrinsic NiP catalyst. The bifunctional NiRe-IP6 catalyst can drive 100 mA/cm2 glucose oxidation reaction (GOR) and hydrogen evolution reaction (HER) processes by only 1.28 V [vs reversible hydrogen electrode (RHE)] and −0.115 V (vs RHE) in alkaline glucose electrolyte, respectively, outperforming almost all the as-reported GOR/HER bifunctional catalysts, especially at high current density.

Galvanostatic method assembled ZIFs nanostructure as novel nanozyme for the glucose oxidation and biosensing

Recently, the composite of soft conductive substrates, such as carbon fiber (CF), with metal-organic frameworks (MOFs) has been employed in a myriad of applications. The composite material has demonstrated exceptional potential in the realm of electrochemical sensing platforms. However, the rapid growth of MOFs on the surface of CF remains a challenge. Herein, we propose a simple galvanostatic method as an effective strategy for rapidly growing zeolitic imidazolate frameworks (ZIFs) on CF, and obtain nano-caltrop-like ZIFs modified CF (NC-ZIFs/CF) glucose (Glu) sensor platform with distinctive morphology. The prepared NC-ZIFs/CF demonstrated significant electrocatalytic activity towards the oxidation of Glu in alkaline media, characterized by a pronounced augmentation in oxidation current density. At an applied potential of 0.4 V, NC-ZIFs/CF exhibited a remarkably broad detection range (3–30,000 µmol/L) and demonstrated outstanding selectivity, repeatability and reproducibility. Additionally, the NC-ZIFs/CF was efficaciously employed for the detection of blood Glu levels in the serum of both normoglycemic and hyperglycemic patients, obtaining highly reliable results. This work demonstrates the feasibility of using galvanostatic method assembly to induce the growth of MOFs on conductive substrates, providing new ideas for electrocatalysis sensors and other electrochemical applications.

Rapid and facile preparation of NiFe-layered double hydroxide nanosheets as self-supported electrode for glucose detection in drink sample

Layered double hydroxides have been widely used for electrochemical glucose detection due to their layered structure with more active sites, but they suffer from lower electrical conductivity and long-time hydrothermal preparation. In this paper, NiFe-layered double hydroxide nanosheets supported on nickel foam (NiFe-LDH NSs/NF) was prepared using an ultrafast and facile method via in-situ corroding foam nickel in FeCl3 solution under room temperature, and the whole synthetic process can be accomplished within several minutes. The as-fabricated NiFe-LDH NSs/NF shows significant catalytic activity in the glucose oxidation, showing its great promise in glucose detection. As a self-supported electrode, NiFe-LDH NSs/NF is favorable for glucose detection, with a sensitivity of 9.79 and 3.29 mA mM−1 cm−2 within the linear range of 0.001 to 1.16 mM and 1.16 to 4.67 mM, respectively. Moreover, NiFe-LDH NSs/NF is also selective and reliable towards glucose detection in drink sample.

Electrochemiluminescence enzyme biosensors for ultrasensitive determination of glucose using glucose dehydrogenase immobilized on vertical silica nanochannels

Accurate determination of glucose in biological samples is of great significance for healthcare monitoring and medical diagnosis. Herein we reported an economical "signal-on" glucose electrochemiluminescence (ECL) enzyme biosensor for ultrasensitive detection of glucose based on vertically-ordered mesoporous silica films (VMSF) covalently modified with a monolayer of glucose dehydrogenase (GDH). In the presence of glucose, β-nicotinamide adenine dinucleotide sodium salt (NAD+)-dependent GDH on the surface of VMSF catalyzes the oxidation of glucose and β-nicotinamide adenine dinucleotide (NADH) reduced from NAD+ is generated concomitantly in situ. The access of NADH to underlying electrode surface is prohibited by ultrasmall nanopores, but it can act as a co-reactant to promote the ECL intensity of Ru(bpy)32+ by the free diffusion of Ru-related species, exhibiting a unique catalytic route. By recording the ECL intensity of Ru(bpy)32+ electrostatically amplified by VMSF, the present ECL enzyme biosensor allows the ultrasensitive detection of glucose substrate with a wide linear range (10 nM to 1 mM) and a rather low limit of detection (1.5 nM). Furthermore, the developed ECL enzyme biosensor is capable of anti-fouling and accurate detection of glucose in human serum and artificial sweat without tedious preprocessing, which provides a ECL enzyme sensing platform for ultrasensitive detection of a variety of substrates of interest by simply tailoring the recognition elements.

Genome-Wide Characterization of Berberine Bridge Enzyme Gene Family in Wheat (Triticum aestivum L.) and the Positive Regulatory Role of TaBBE64 in Response to Wheat Stripe Rust.

Berberine bridge enzymes (BBEs), functioning as carbonate oxidases, enhance disease resistance in Arabidopsis and tobacco. However, the understanding of BBEs' role in monocots against pathogens remains limited. This study identified 81 TaBBEs with FAD_binding_4 and BBE domains. Phylogenetic analysis revealed a separation of the BBE gene family between monocots and dicots. Notably, RNA-seq showed TaBBE64's significant induction by both pathogen-associated molecular pattern treatment and Puccinia striiformis f. sp. tritici (Pst) infection at early stages. Subcellular localization revealed TaBBE64 at the cytoplasmic membrane. Knocking down TaBBE64 compromised wheat's Pst resistance, reducing reactive oxygen species and promoting fungal growth, confirming its positive role. Molecular docking and enzyme activity assays confirmed TaBBE64's glucose oxidation to produce H2O2. Since Pst relies on living wheat cells for carbohydrate absorption, TaBBE64's promotion of glucose oxidation limits fungal growth and resists pathogen infection. This study sheds light on BBEs' role in wheat resistance against biotrophic fungi.

Non-enzymatic glucose electrochemical sensor based on nitrogen-doped graphene modified with polyaniline and Fe3O4@MIL-101-NH2 nano framework

In this study, a novel highly sensitive and selective non-enzymatic glucose sensor was fabricated by coating simple and cheap graphite sheet (GS) electrodes with a proper conductive nanocomposite containing nitrogen-doped functionalized graphene (NFG), conductive polyaniline (PANI), and core–shell nanoparticles (Fe3O4@MIL-101-NH2). The results revealed that the core centers of iron oxide nanoparticles shelled by MIL-101-NH2 enhanced the electron transfer and led to more conductivity, also their existence caused the limitation of the MOF’s low conductivity. In addition, using Fe3O4@MIL-101-NH2 in the nanocomposite structure led to more sensitivity and selectivity at glucose monitoring due to its amine groups and unique structure. The results showed that NFG/PANI/Fe3O4@MIL-101-NH2 nanocomposite provided a large surface area besides enhanced electron transfer and catalytic properties that lead to proper oxidation of glucose with two linear ranges of 0.5 – 10 µM and 100 µM – 25 mM and a low detection limit of 0.3 µM (S/N = 3). Furthermore, the relative standard deviation (RSD%) in all detection processes was lower than 9 %. Finally, the performance of fabricated non-enzymatic sensor (GS/NFG/PANI/Fe3O4@MIL-101-NH2) in human fluids real samples including serum and plasma was acceptable which significantly indicates that it is toward monitoring of glucose in clinical applications.

Rapid Synthesis of Trimetallic Nanozyme for Sustainable Cascaded Catalytic Therapy via Tumor Microenvironment Remodulation.

Tumor microenvironment (TME)-responsive nanozyme-catalyzed cancer therapy shows great potential due to its specificity and efficiency. However, breaking the self-adaption of tumors and improving the sustainable remodeling TME ability remains a major challenge for developing novel nanozymes. Here, a rapid method is developed first to synthesize unprecedented trimetalic nanozyme (AuMnCu, AMC) with a targeting peptide (AMCc), which exhibits excellent peroxidase-like, catalase-like, and glucose oxidase-like activities. The released Cu and Mn ions in TME consume endogenous H2 O2 and produce O2 , while theAMCccatalyzes glucose oxidation reaction to generate H2 O2 and gluconic acid, which achieves the starvation therapy by depleting the energy and enhances the chemodynamic therapy effect by lowering the pH of the TME and producing extra H2 O2 . Meanwhile, the reactive oxygen species damage is amplified, as AMCc can constantly oxidize intracellular reductive glutathione through the cyclic valence alternation of Cu and Mn ions, and the generated Cu+ elevate the production of ·OH from H2 O2 . Further studies depict that the well-designed AMCc exhibits the excellent photothermal performance and achieves TME-responsive sustainable starvation/photothermal-enhanced chemodynamic synergistic effects in vitro and in vivo. Overall, a promising approach is demonstrated here to design "all-in-one" nanozyme for theranostics by remodeling the TME.

Probing human heart TCA cycle metabolism and response to glucose load using hyperpolarized [2-13 C]pyruvate MRS.

The healthy heart has remarkable metabolic flexibility that permits rapid switching between mitochondrial glucose oxidation and fatty acid oxidation to generate ATP. Loss of metabolic flexibility has been implicated in the genesis of contractile dysfunction seen in cardiomyopathy. Metabolic flexibility has been imaged in experimental models, using hyperpolarized (HP) [2-13 C]pyruvate MRI, which enables interrogation of metabolites that reflect tricarboxylic acid (TCA) cycle flux in cardiac myocytes. This study aimed to develop methods, demonstrate feasibility for [2-13 C]pyruvate MRI in the human heart for the first time, and assess cardiac metabolic flexibility. Good manufacturing practice [2-13 C]pyruvic acid was polarized in a 5 T polarizer for 2.5-3 h. Following dissolution, quality control parameters of HP pyruvate met all safety and sterility criteria for pharmacy release, prior to administration to study subjects. Three healthy subjects each received two HP injections and MR scans, first under fasting conditions, followed by oral glucose load. A 5 cm axial slab-selective spectroscopy approach was prescribed over the left ventricle and acquired at 3 s intervals on a 3 T clinical MRI scanner. The study protocol, which included HP substrate injection, MR scanning, and oral glucose load, was performed safely without adverse events. Key downstream metabolites of [2-13 C]pyruvate metabolism in cardiac myocytes include the glycolytic derivative [2-13 C]lactate, TCA-associated metabolite [5-13 C]glutamate, and [1-13 C]acetylcarnitine, catalyzed by carnitine acetyltransferase (CAT). After glucose load, 13 C-labeling of lactate, glutamate, and acetylcarnitine from 13 C-pyruvate increased by an average of 39.3%, 29.5%, and 114% respectively in the three subjects, which could result from increases in lactate dehydrogenase, pyruvate dehydrogenase, and CAT enzyme activity as well as TCA cycle flux (glucose oxidation). HP [2-13 C]pyruvate imaging is safe and permits noninvasive assessment of TCA cycle intermediates and the acetyl buffer, acetylcarnitine, which is not possible using HP [1-13 C]pyruvate. Cardiac metabolite measurement in the fasting/fed states provides information on cardiac metabolic flexibility and the acetylcarnitine pool.