Specific Detection Of Glucose Research Articles

Fabrication of natural enzyme-covered / amino-modified Pd-Pt bimetallic-doped zeolitic imidazolate framework for ultrasensitive detection of metabolites.

The present article introduced an natural enzyme-covered/amino-modified Pd-Pt bimetallic-doped zeolitic imidazolate framework (NAPPZ) for ultrasensitive and specific detection of glucose. The dodecahedral nanomaterial zeolitic imidazolate framework (ZIF-8)-loaded Pd-Pt bimetallic nanoparticles endowed the composite with peroxidase-like activity. The modification with glucose oxidase (GOx) facilitated the rapid access of H2O2 produced through glucose oxidation to the Pd-Pt nanoparticles vicinity reducing diffusion. GOx specifically catalyzes the transformation of glucose into H2O2, which then H2O2 rapidly migrates to the Pd-Pt nanoparticles, catalyzing the oxidation of colorless o-phenylenediamine into the orange-yellow product 2,3-diaminophenazine. Based on the aforementioned cascade reaction, the NAPPZ and NAPPZ based on ChOx were utilized for detecting glucose in human urine samples and cholesterol in milk, respectively. The NAPPZ strategy presented a broad detection range (20-1100μmol L-1) and a low detection limit (15.9μmol L-1) for glucose, and the NAPPZ based on ChOx strategy approach offered a broad detection range (10-500μmol L-1) and low detection limit (6.4μmol L-1) for cholesterol. Therefore, this novel method holds significant potential in the areas of clinical diagnostics and food safety.

Design, fabrication, and characterization of a polymer-based waveguide Bragg grating for blood glucose monitoring

A waveguide Bragg grating (WBG) can facilitate an adaptable method for glucose monitoring according to the optical properties of polymer materials. We propose the design and fabrication of a WBG for glucose monitoring. By exploiting glucose oxidase as the upper cladding, polydimethylsiloxane was used as the substrate, and polymethyl methacrylate was used as the core layer. We investigated the effects of the diffraction order, waveguide structure, and grating period on the reflected spectrum of the WBG. Finally, process reproducibility after long-term storage and the capability to eliminate background solution interference (to achieve more specific glucose detection) were evaluated. The experimental results showed that when the glucose concentration was in the range of [0, 3.6] mg/ml, as the glucose concentration increased, the wavelength decreased approximately linearly, with a sensitivity of approximately 242.9 pm/(mg/ml) in the range of 0–2.7 mg/ml, while maintaining good selectivity and stability. The WBG for glucose monitoring has the advantages of a large measurement range and high sensitivity. This approach facilitates the application potential of such polymer material-based WBG photonic sensors in wearable technology and realizes the measurement of human blood glucose.

A smartphone-assisted colorimetric sensor based on Fe1-xS nanozyme for detection of glucose and ascorbic-acid in soft drinks

Due to their distinct enzyme-like catalytic activity, iron-based nanomaterials have attracted considerable attention from researchers in the field of biomolecular detection. However, the current literature predominantly focuses on iron oxide nanozymes, with limited attention given to iron sulfide (FexSy) nanozymes. In this work, a glutathione-modified Fe1-xS nanoparticles (Fe1-xS NPs) with a diameter of 4–6 nm was synthesized in one-pot aqueous solution at room temperature. The resulting Fe1-xS NPs exhibited superior peroxidase-like (POD) activity compared to natural horseradish peroxidase, indicating their potential as a promising alternative for POD applications. A sensor utilizing the POD activity of Fe1-xS NPs was developed for detecting glucose and ascorbic-acid (AA) in soft drinks. The detection limits for glucose and AA were determined to be 37 and 5.3 μM, respectively, with broader linear ranges of 200–700 and 10–500 μM. Moreover, Fe1-xS NPs demonstrated exceptional selectivity and anti-interference properties in detecting glucose and AA in soft drinks. Furthermore, this study proposed a smartphone-assisted colorimetric sensor based on Fe1-xS nanozymes for rapid and specific detection of glucose and AA. This technique has the potential to be utilized in the future for convenient and efficient detection of glucose and AA.

Two-Dimensional Transition Metal Dichalcogenide Tunnel Field-Effect Transistors for Biosensing Applications.

Field-effect transistor (FET) biosensors based on two-dimensional (2D) materials have drawn significant attention due to their outstanding sensitivity. However, the Boltzmann distribution of electrons imposes a physical limit on the subthreshold swing (SS), and a 2D-material biosensor with sub-60 mV/dec SS has not been realized, which hinders further increase of the sensitivity of 2D-material FET biosensors. Here, we report tunnel FETs (TFETs) based on a SnSe2/WSe2 heterostructure and observe the tunneling effect of a 2D material in aqueous solution for the first time with an ultralow SS of 29 mV/dec. A bilayer dielectric (Al2O3/HfO2) and graphene contacts, which significantly reduce the leakage current in solution and contact resistance, respectively, are crucial to the realization of the tunneling effect in solution. Then, we propose a novel biosensing method by using tunneling current as the sensing signal. The TFETs show an extremely high pH sensitivity of 895/pH due to ultralow SS, surpassing the sensitivity of FET biosensors based on a single 2D material (WSe2) by 8-fold. Specific detection of glucose is realized, and the biosensors show a superb sensitivity (3158 A/A for 5 mM), wide sensing range (from 10-9 to 10-3 M), low detection limit (10-9 M), and rapid response rate (11 s). The sensors also exhibit the ability of monitoring glucose in complex biofluid (sweat). This work provides a platform for ultrasensitive biosensing. The discovery of the tunneling effect of 2D materials in aqueous solution may stimulate further fundamental research and potential applications.

Ti2C-TiO2 MXene Nanocomposite-Based High-Efficiency Non-Enzymatic Glucose Sensing Platform for Diabetes Monitoring.

Diabetes is a major health challenge, and it is linked to a number of serious health issues, including cardiovascular disease (heart attack and stroke), diabetic nephropathy (kidney damage or failure), and birth defects. The detection of glucose has a direct and significant clinical importance in the management of diabetes. Herein, we demonstrate the application of in-situ synthesized Ti2C-TiO2 MXene nanocomposite for high throughput non-enzymatic electrochemical sensing of glucose. The nanocomposite was synthesized by controlled oxidation of Ti2C-MXene nanosheets using H2O2 at room temperature. The oxidation results in the opening up of Ti2C-MXene nanosheets and the formation of TiO2 nanocrystals on their surfaces as revealed in microscopic and spectroscopic analysis. Nanocomposite exhibited considerably high electrochemical response than parent Ti2C MXene, and hence utilized as a novel electrode material for enzyme-free sensitive and specific detection of glucose. Developed nanocomposite-based non-enzymatic glucose sensor (NEGS) displays a wide linearity range (0.1 µM-200 µM, R2 = 0.992), high sensitivity of 75.32 μA mM−1 cm−2, a low limit of detection (0.12 μM) and a rapid response time (~3s). NEGS has further shown a high level of repeatability and selectivity for glucose in serum spiked samples. The unveiled excellent sensing performance of NEGS is credited to synergistically improved electrochemical response of Ti2C MXene and TiO2 nanoparticles. All of these attributes highlight the potential of MXene nanocomposite as a next-generation NEGS for on the spot mass screening of diabetic patients.

Optical fiber SPR biosensor with a solid-phase enzymatic reaction device for glucose detection

A portable and user-friendly optical fiber sensing platform for rapid glucose detection based on surface plasmon resonance (SPR) sensing and enzymatic reaction is proposed. We designed a simple and easy-to-use miniaturized device for the specific decomposition of glucose; the device can fully react with glucose samples and produce glucose-free samples. The optical fiber SPR biosensor was prepared for detecting glucose samples before and after enzymatic reaction through the device, and to obtain an SPR differential signal that corresponds specifically to glucose concentration. Different levels of urine glucose concentrations in a broad range of 0–400 mg/dL were distinguished by the proposed method with a sensitivity of 3.10 pm/(mg/dL). Our novel method has the following advantages: (1) the sensor and enzymatic reaction device can be reused with low cost; (2) the interference of the background solution can be eliminated for more specific glucose detection; (3) the operation is simple and fast without requiring professional operation skills, and the test samples can be directly loaded/released for detecting; (4) the platform is also suitable for the specific detection of other enzymatic reactions by changing the reaction enzyme. The platform provides a new pathway for the detection of food additives and medical immunoassays.

Sensitive silica‐alumina modified capacitive non‐Faradaic glucose sensor for gestational diabetes

A highly sensitive silica-alumina (Si-Al)-modified capacitive non-Faradaic glucose biosensor was introduced to monitor gestational diabetes. Glucose oxidase (GOx) was attached to the Si-Al electrode surface as the probe through amine-modification followed by glutaraldehyde premixed GOx as aldehyde-amine chemistry. This Si-Al (∼50 nm) modified electrode surface has increased the current flow upon binding of GOx with glucose. Capacitance values were increased by increasing the glucose concentrations. A mean capacitance value was plotted and the detection limit was found as 0.03 mg/mL with the regression coefficient value, R² = 0.9782 [y = 0.8391x + 1.338] on the linear range between 0.03 and 1 mg/mL. Further, a biofouling experiment with fructose and galactose did not increase the capacitance, indicating the specific glucose detection. This Si-Al-modified capacitance sensor detects a lower level of glucose presence and helps in monitoring gestational diabetes.

A D-shaped fiber SPR sensor with a composite nanostructure of MoS2-graphene for glucose detection

Fiber-based techniques make it possible to implant a miniaturized and flexible surface plasmon resonance (SPR) sensor into the human body for glucose detection. However, the miniaturization of fiber SPR sensors results in low sensitivity compared with traditional prism-type SPR sensors due to limited sensing area. In this paper, we proposed a D-shaped fiber SPR sensor with a composite nanostructure of molybdenum disulfide (MoS2)-graphene to improve the sensor sensitivity. Compared with the traditional cylindrical fiber, the planar sensing area on the side-polished fiber makes it easier to modify two-dimensional materials. Chemical vapor deposition (CVD) graphene and CVD MoS2 were modified on the sensor surface to obtain the MoS2-graphene composite nanostructure. π-π stacking interactions were used to modify pyrene-1-boronic acid (PBA) on the graphene. The excellent photoelectric properties of the MoS2-graphene composite nanostructure and the ability of PBA to specifically bind glucose molecules improved the glucose detection performance of the SPR sensor. The results show that specific detection of glucose was realized and that the highest sensitivity was achieved with three-layer MoS2 and monolayer graphene.

"Switch-On" Fluorescence Detection of Glucose with High Specificity and Sensitivity Based on Silver Nanoparticles Supported on Porphyrin Metal-Organic Frameworks.

As the energy source of living cells and the intermediate product of metabolism, glucose plays an important role in biological systems. Therefore, it is of great significance to establish a reliable and sensitive method for the detection of glucose, especially in blood. Herein, a "switch-on" fluorescence sensor for rapid, sensitive, and specific detection of glucose was successfully developed. In this strategy, PCN-224 served as the recognition unit, while AgNPs played the roles as both a "quencher", to decrease the fluorescence intensity of PCN-224, and an H2O2 recognizer. After exposure to H2O2 that was produced in situ during GOx-catalyzed oxidation of glucose, AgNPs can be effectively etched into silver ions and released from PCN-224, thereby recovering the fluorescence of PCN-224. The present sensing strategy shows many merits including high sensitivity with a low limit of detection (0.078 μM) and excellent selectivity toward glucose over other saccharides. More importantly, the sensing platform we proposed was further extended to monitoring glucose in human serum samples with satisfactory recoveries, indicating its promising potential for diagnostic purposes.

Carbon Nanotube Paper‐based Electrode for Electrochemical Detection of Chemicals in Rat Microdialysate

AbstractPaper‐based analytical devices, which are suited to point‐of‐care diagnostics and on‐site detection because of cheap price and portability, have attracted increasing attention for improving global health and in other applications. Here, we constructed one carbon nanotube paper‐based electrode (CNTPE) for the detection of neurochemicals in brain microdialysate. CNTPE was directly fabricated through filter depositing CNT dispersion onto the surface of filter paper. The fabricated CNTPE have good electrochemical performance with advantage of CNT, which not only facilitate ascorbic acid (AA) oxidation, also could as a good platform to functionalize. As a proof, we demonstrate that the CNTPE act as electrode to detect AA directly and detect glucose with further modified CNTPE through electrodeposited Prussian blue (PB). The results show that the easily prepared CNTPE can be used for the selective measurement of AA without interference from dopamine and other electrochemical active substances; what's more, PB and glucose oxidase (GOx) modified CNTPE has good performance towards the specific detection of glucose. Therefore, we believe that CNTPE would have great potential application in detection of chemicals to understand the function of brain.

Enzyme-functionalized thin-cladding long-period fiber grating in transition mode at dispersion turning point for sugar-level and glucose detection.

Enzyme-functionalized dual-peak long-period fiber grating (LPFG) inscribed in 80 - ? m -cladding B/Ge codoped single-mode fiber is presented for sugar-level and specific glucose detection. Before enzyme functionalization, the dual-peak LPFG was employed for refractive index sensing and sugar-level detection and high sensitivities of ? 4298.20 ?? nm / RIU and 4.6696 ?? nm / % were obtained, respectively. Glucose detection probe was attained by surface functionalization of the dual-peak LPFG via covalent binding with aminopropyl triethoxysilane used as a binding site. Optical micrographs confirmed the presence of enzyme. The surface-functionalized dual-peak LPFG was tested with D-(+)-glucose solution of different concentrations. While the peak 2 at the longer wavelength was suitable only to measure lower glucose concentration (0.1 to 1.6 ?? mg / ml ) recording a high sensitivity of 12.21 ± 0.19 ?? nm / ( mg / ml ) , the peak 1 at the shorter wavelength was able to measure a wider range of glucose concentrations (0.1 to 3.2 ?? mg / ml ) exhibiting a maximum resonance wavelength shift of 7.12 ± 0.12 ?? nm / mg / ml . The enzyme-functionalized dual-peak LPFG has the advantage of direct inscription of highly sensitive grating structures in thin-cladding fibre without etching, and most significantly, its sensitivity improvement of approximately one order of magnitude higher than previously reported LPFG and excessively tilted fibre grating (Ex-TFG) for glucose detection.

Engineering mediatorless glucose oxidase microbioreactor

Event Abstract Back to Event Engineering mediatorless glucose oxidase microbioreactor Geraldine Merle1*, Joao H. Lopes1*, Francois-Xavier Colson1* and Jake E. Barralet1* 1 McGill University, Dentistry, Canada Introduction: Accomplishing a transfer direct of electrons (DET) between the enzyme and the electrodes has become a great challenge in the development of biosensor and biopile[7]. The electron-tunneling distance can be diminished with structured conducting nanomaterials to enable DET. Glucose monitoring has an important significance in medicine with the routine analysis of glucose in blood or in environment and food industry. Glucose oxidase (GOx) technology has been already commercialised through the disposable glucose sensor strips however, the main hurdle of this system is the limited detection (10-3-10-6 M). Here, we successfully enhanced the conductivity while immobilizing GOx by self-assemblying GOx with TiO2 and carbon nanotubes. This has led to the development of an ultrasensitive, selective and inexpensive biosensor with a detection limit in the micro-molar range, which can be further miniaturised. Experimental: Briefly, GOx, TiO2, Na3PO4 and CNT solution were mixed together with a final weight ratio of TiO2/CNT of 0.6 wt% and dried. The mixture was self-assembled into nanoporous microparticles following Bassett et al. [1] Finally, the suspension was filtered through a 75 µm sieve and the particles ≥75 μm diameter were collected and dried. Beside the determination of the physico-chemical properties of the microparticle such as specific surface area and morphology, enzymatic and electrochemical activity measurements were performed. Results and Discussion: The morphology of microparticles was investigated with SEM. It can be clearly seen at higher magnification the carbon nanotubes entangled with the TiO2 nanoparticles compared to the pristine TiO2. The biocatalytic activities of free GOx and immobilized GOx were investigated by monitoring the oxidation of glucose in the presence of horseradish peroxidase. Despite a lower Vmax for the immobilised GOx (0.063 µM/min) compared to the free enzyme (0.65 µM/min), a KM value of approximately 17.5 mM and 23.5mM was found for free and immobilised GOx respectively, confirming that the self-assembly process and the nano-environment do not alter the affinity of the enzyme for the substrate[2][3]. The residual activity for the microbioparticle remained high with a gradual decrease up to 40% of its initial activity after 30 days storage at 4°C, probably as a consequence of the desorption and leaching of enzyme. Cyclic voltammetry experiments show in the absence of GOx, no significant redox peaks whereas the microbioparticle exhibits a of well-defined peaks at -0.2 V vs SCE reference electrode, ascribed only to GOx and more specifically to the redox active center (FAD/FADH2)[4]. This confirms the key role of the CNTs assembled with TiO2 in promoting successfully the direct electron transfer between GOD and the electrode surface. The detection of glucose by chronoamperometric method shows a fast (less than 3s) response time of the biosensor to the added glucose and a current response stable in 2min. The glucose biosensor exhibits a sensitivity of 17.16 µA.mM-1cm-2 and a high selectivity for glucose.[5][6] Conclusion: Mediating DET by engineering the structures at the nanometer scale has been performed by assembling GOx with CNT and TiO2 in one step synthesis. While greatly stabilizing the GOX, this nanostructures allow the specific detection of glucose by wiring the electrons from the active site of the GOX to the electrode and opens new avenues for others biosensors. This work was carried out with the support of the São Paulo Research Foundation – FAPESP (Grant 2013/12376-5). Natural Sciences and Engineering Research Council of Canada (NSERC)

Glucose sensing by waveguide-based absorption spectroscopy on a silicon chip.

In this work, we demonstrate in vitro detection of glucose by means of a lab-on-chip absorption spectroscopy approach. This optical method allows label-free and specific detection of glucose. We show glucose detection in aqueous glucose solutions in the clinically relevant concentration range with a silicon-based optofluidic chip. The sample interface is a spiral-shaped rib waveguide integrated on a silicon-on-insulator (SOI) photonic chip. This SOI chip is combined with micro-fluidics in poly(dimethylsiloxane) (PDMS). We apply aqueous glucose solutions with different concentrations and monitor continuously how the transmission spectrum changes due to glucose. Based on these measurements, we derived a linear regression model, to relate the measured glucose spectra with concentration with an error-of-fitting of only 1.14 mM. This paper explains the challenges involved and discusses the optimal configuration for on-chip evanescent absorption spectroscopy. In addition, the prospects for using this sensor for glucose detection in complex physiological media (e.g. serum) is briefly discussed.

Sensitive SERS glucose sensing in biological media using alkyne functionalized boronic acid on planar substrates

In this work, we propose a novel glucose binding mechanism on a highly sensitive SERS substrate, in order to overcome challenges in specific glucose detection in bio-fluids. We make use of phenylboronic acid as a receptor for saccharide capture onto the substrate and the ability of the captured glucose molecule to undergo secondary binding with an alkyne-functionalized boronic acid to form a glucose–alkyne–boronic acid complex. The formation of this complex shows high selectivity for glucose, over other saccharides. In addition, the alkyne group of the alkyne-functionalized boronic acid exhibits a distinct Raman peak at 1996cm−1 in a biological silent region (1800–2800cm−1) where most endogenous molecules, including glucose, show no Raman scattering, thus offering a high sensitivity over other SERS glucose sensing. The substrate offers long-term stability, as well as high SERS enhancement to the glucose–alkyne boronic acid complex on substrate. In addition, the reversibility of SERS signals at various incubation stages also shows reusability capabilities, whereas positive results in clinical urine samples demonstrate clinical feasibility. All these strongly suggest that this newly developed SERS-based assay offers great potential in glucose sensing.

Glucose-triggered signalling in Saccharomyces cerevisiae: different requirements for sugar phosphorylation between cells grown on glucose and those grown on non-fermentable carbon sources.

Addition of glucose or fructose to cells of the yeast Saccharomyces cerevisiae grown on a nonfermentable carbon source triggers within a few minutes posttranslational activation of trehalase, repression of the CTT1 (catalase) and SSA3 (Hsp70) genes, and induction of the ribosomal protein genes RPL1, RPL25 and RPS33. By using appropriate sugar kinase mutants, it was shown that rapid glucose- or fructose-induced activation of trehalase requires phosphorylation of the sugar. On the other hand, partial induction of RPL1, RPL25 and RPS33 as well as partial repression of CTT1 and SSA3 were observed in the absence of sugar phosphorylation. In glucose-grown nitrogen-starved yeast cells readdition of a nitrogen source triggers activation of trehalase in a glucose- or fructose-dependent way, but with no apparent requirements for phosphorylation of the sugar. Repression of CTT1 and SSA3 under the same conditions was also largely dependent on the presence of the sugar and also in these cases there was a strong effect when the sugar could not be phosphorylated. Nitrogen induction of RPL1, RPL25 and RPS33 was much less dependent on the presence of the sugar, and only phosphorylated sugar caused a further increase in expression. These results show that two glucose-dependent signalling pathways, which can be distinguished on the basis of their requirement for glucose phosphorylation, appear to be involved in activation of trehalase, repression of CTT1 and SSA3 and induction of ribosomal protein genes. They also show that nutrient-induced repression of CTT1 and SSA3 is not a response to improvement of the growth conditions because the addition of nonmetabolizable sugar does not ameliorate the growth conditions. Similarly, the upshift in ribosomal protein synthesis cannot be a response to increased availability of energy or biosynthetic capacity derived from glucose, but it is apparently triggered to a significant extent by specific detection of glucose as such.