Glucose Levels In Human Serum Research Articles

Rapid colorimetric detection of H2O2 in living cells and its upstream series of molecules based on oxidase-like activity of CoMnO3 nanofibers

Most studies on nanozymes in recent years have focused on enhancing their catalytic activity and synthesizing directly, although this task is still complicated. Bimetallic oxides are particularly desirable due to their mixed valence and structural properties. In this study, bimetallic oxide nanofibers (CoMnO3 NFs) were prepared using a quick and effective hydrothermal synthesis technique, and exhibited outstanding oxidase-like activity. The catalytic activity of CoMnO3 NFs displayed an inhibitory response on exposure to H2O2, which was applied in detecting H2O2 and its upstream molecules (glucose and uric acid). Based on this, a straightforward, affordable, and accurate colorimetric approach was developed by combining with 3,3′,5,5′-tetramethylbenzidine. Employing the oxidase activity rather than the traditional peroxidase activity to detect H2O2 drastically reduces the detection time. This method was also successfully used for in situ quantitative monitoring of intracellular H2O2, as well as detecting uric acid and glucose levels in human serum. Moreover, a smartphone-assisted colorimetric sensing system built on self-developed software was developed, enabling the on-site detection of H2O2 without laboratory instruments. This study established theoretical support for the valid design of bimetallic oxide nanozyme activity and might guide the development of detection systems for accurately analyzing biomarkers in foods and biochemical products.

Reduced graphene oxide supported MXene based metal oxide ternary composite electrodes for non-enzymatic glucose sensor applications

Diagnosis and monitoring of glucose level in human blood has become a prime necessity to avoid health risk and to cater this, a sensor’s performance with wide linearity range and high sensitivity is required. This work reports the use of ternary composite viz. MG–Cu2O (rGO supported MXene sheet with Cu2O) for non-enzymatic sensing of glucose. It has been prepared by co-precipitation method and characterized with X-ray powder diffraction, Ultraviolet–visible absorption spectroscopy (UV–Vis), Raman spectroscopy, Field emission scanning electron microscopy, High resolution transmission electron microscopy and Selected area diffraction. These analyses show a cubic structure with spherical shaped Cu2O grown on the MG sheet. Further, the electrocatalytic activity was carried out with MG–Cu2O sensing element by cyclic voltammetry and chronoamperometry technique and compared with M–Cu2O (MXene with Cu2O) composite without graphene oxide. Of these, MG–Cu2O composite was having the high defect density with lower crystalline size of Cu2O, which might enhance the conductivity thereby increasing the electrocatalytic activity towards the oxidation of glucose as compared to M–Cu2O. The prepared MG–Cu2O composite shows a sensitivity of 126.6 µAmM−1 cm−2 with a wide linear range of 0.01to 30 mM, good selectivity, good stability over 30 days and shows a low Relative Standard Deviation (RSD) of 1.7% value towards the sensing of glucose level in human serum. Thus, the aforementioned finding indicates that the prepared sensing electrode is a well suitable candidate for the sensing of glucose level for real time applications.

Coaxial electrospinning synthesis of size-tunable CuO/NiO hollow heterostructured nanofibers: Towards detection of glucose level in human serum

Nanofibers (NFs) have found wide applications by virtue of their particular morphology and high specific surface area. In this study, size-tunable hollow CuO/NiO NFs were synthesized by coaxial electrospinning and subsequent calcination. The synthesized hollow CuO/NiO NFs owned large specific surface area for catalytic active sites. In addition, the formation of heterostructure interface between CuO and NiO was beneficial to improve the electrocatalytic performance. As non-enzymatic electrode material, the synthesized CuO/NiO NFs exhibited superior electrocatalytic capability for glucose oxidation. When the molar ratio of CuO to NiO is 0.4, the composite NFs achieved the optimal electrocatalytic ability for glucose oxidation, performing high sensitivity of 1324.17 μA mM−1 cm−2 and wide liner range from 1 to 10,000 μM. The constructed electrode has been utilized to detect glucose concentration in real serum with excellent recovery, indicating that CuO/NiO hollow heterostructured NFs are promising materials for biomedical applications.

Reusable, Non-Invasive, and Ultrafast Radio Frequency Biosensor Based on Optimized Integrated Passive Device Fabrication Process for Quantitative Detection of Glucose Levels.

The increase in the number of people suffering diabetes has been the driving force behind the development of glucose sensors to overcome the current testing shortcomings. In this work, a reusable, non-invasive and ultrafast radio frequency biosensor based on optimized integrated passive device fabrication process for quantitative detection of glucose level was developed. With the aid of the novel biosensor design with hammer-shaped capacitors for carrying out detection, both the resonance frequency and magnitude of reflection coefficient can be applied to map the different glucose levels. Meanwhile, the corresponding fabrication process was developed, providing an approach for achieving quantitative detection and a structure without metal-insulator-metal type capacitor that realizes low cost and high reliability. To enhance the sensitivity of biosensor, a 3-min dry etching treatment based on chlorine/argon-based plasma was implemented for realizing hydrophilicity of capacitor surface to ensure that the biosensor can be touched rapidly with glucose. Based on above implementation, a non-invasive biosensor having an ultrafast response time of superior to 0.85 s, ultralow LOD of 8.01 mg/dL and excellent reusability verified through five sets of measurements are realized. The proposed approaches are not limited the development of a stable and accurate platform for the detection of glucose levels but also presents a scheme toward the detection of glucose levels in human serum.

Synthesis of Co3O4-NiO nano-needles for amperometric sensing of glucose

In this paper, needle-like Co3O4-NiO nanocomposites with excellent electrocatalytic activity were served as electrode matrix for constructing novel electrochemical glucose sensor. The Co3O4-NiO nanocomposites were synthesized via a simple two-step procedure, showing a uniform geometric size with average length and diameter about 465 and 25nm, respectively. The Co3O4-NiO composites exhibited random distributed nano-needles were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. In addition, the needle-like Co3O4-NiO nanocomposites were used as an electrode material for constructing nonenzymatic electrochemical glucose sensor and their electrocatalytic performances were evaluated by cyclic voltammetry and amperometry techniques. The sensor exhibited a wide linear response in the 1μM to 3.4mM and 3.4mM to 12.2mM glucose concentration ranges, a low detection limit of 0.81μM and a high sensitivity of 62mAM−1cm−2 (S/N=3). Furthermore, the prepared sensor was utilized to detect the glucose levels in human serum, and satisfactory results were obtained. It demonstrated that needle-like Co3O4-NiO nanocomposites are promising materials in practical electrochemical sensing.

Elemental Cu doped Co3O4 thin film for highly sensitive non-enzymatic glucose detection

We report on the non-enzymatic glucose sensing ability of elemental Cu doped Co3O4 thin film deposited on FTO in this study. A facile chemical solution method was used to substitute elemental Cu into the Co3O4 host lattice. The morphology of the electrode was characterized by XRD, SEM, HRTEM, SAED and EELS. The as prepared thin film exhibited very high sensitivity of 1850 μAcm-2 mM−1, and linear range up to 7.6 mM. The sensor showed a limit of detection of 153 nM at a signal to noise ratio of 3. The developed sensor was used successfully to measure glucose level in human serum and spiked saliva samples.

Fabrication and evaluation of a carbon quantum dot/gold nanoparticle nanohybrid material integrated onto planar micro gold electrodes for potential bioelectrochemical sensing applications

We have developed a hybrid nanomaterial based on both of carbon quantum dots(CQDs)/gold nanoparticles(AuNPs), such that the cheapness and versatility on the CQDs is directly combined with the inertness and electrochemical activity of the AuNPs to create a new electrochemical biosensor. Here, for the first time, we demonstrate how this interesting materials combination can be applied in the development of an enzymatic biosensor that is easily manufacturable using standard semiconductor processing methods. To demonstrate the potential and performance of the CQDs as an immobilization matrix, glucose oxidase(GOx) enzyme was chosen as a model system. The analytical performance of the developed biosensor was examined using chronoamperometry and the developed CQDs/AuNPs-GOx biosensor exhibited a sensitivity of 47.24 μA mM−1 cm−2 and a detection limit of 17 μM (S/N = 3) with a linear response to glucose ranging from 0.05 mM to 2.85 mM (R = 0.987). Furthermore, this new biosensor showed a high level of reproducibility and was also shown to be very selective towards glucose in the presence of the possible interference species ascorbic acid, uric acid and acetaminophen. Finally, it is demonstrated that the sensor is also capable of reliably detecting glucose levels in human serum.

Porous Ni3N nanosheet array as a catalyst for nonenzymatic amperometric determination of glucose

A glassy carbon electrode was modified with an array of porous Ni3N nanosheets (Ni3N NA) and studied for its use in non-enzymatic electrochemical detection of glucose. The morphology and structure of the Ni3N NA were characterized by scanning electron microscopy and X-ray diffraction. Electrochemical studies demonstrated that the Ni3N NA acts as an efficient catalyst for the electro-oxidation of glucose at pH13, best at a working voltage of 0.55V (vs. Ag/AgCl). Figures of merit include (a) high sensitivity (39μA·mM-1·cm-2), (b) a low limit of detection (0.48μM), and (c) a linear range that extends from 2μM to 7.5mM. The sensor was applied to the determination of glucose levels in human serum, and satisfactory results were obtained. Graphical abstract Nonenzymatic electrochemical glucose sensor based on porous Ni3N nanosheet array. The arrow indicates the successive addition of glucose standard solutions.

Improved peroxidase mimetic activity of a mixture of WS2 nanosheets and silver nanoclusters for chemiluminescent quantification of H2O2 and glucose

It is reported that a mixture of WS2 nanosheets (WS2 NS) and silver nanoclusters (AgNCs) displays strongly enhanced peroxidase-mimicking activity. The catalytic effect of the mixture was studied by colorimetry, fluorometry, chemiluminescence (CL) and electrochemistry. The effect is interpreted in terms of a difference between the Fermi energy level of the two nanomaterials. This leads to the formation of charge separation regions which act as active sites for enzyme mimetic interaction with the substrates. The mixture of WS2 NS and AgNCs was exploited for the non-enzymatic determination of H2O2 and glucose. A stopped-flow method was applied as a sensitive CL detection system using the bicarbonate-H2O2 reaction. The mixture has a powerful peroxidase mimicking activity on the bicarbonate-H2O2 CL reaction, and this effect is much larger than that of any single constituent. In addition, the CL emission is improved several times by using the stopped-flow technique. Under optimum condition, H2O2 can be determined in the2.5-1500 nM concentration range. Moreover, glucose levels in human serum can be quantified via glucose oxidase based oxidation which leads to the generation of H2O2. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.03-20μM, with a limit of detection (3S) of 13 nM. Graphical abstract An enhanced peroxidase-like catalytic activity for WS2 nanosheets (WS2 NS) was revealed in the presence of silver nanoclusters (AgNCs), and was exploited for the non-enzymatic determination of H2O2,and ofglucose (via glucose oxidase; GOx) using a stopped-flow CL method.

Synthesis of a novel Au nanoparticles decorated Ni-MOF/Ni/NiO nanocomposite and electrocatalytic performance for the detection of glucose in human serum

A nonenzymatic glucose electrochemical sensor was constructed based on Au nanoparticles (AuNPs) decorated Ni metal-organic-framework (MOF)/Ni/NiO nanocomposite. Ni-MOF/Ni/NiO nanocomposite was synthesized by one-step calcination of Ni-MOF. Then AuNPs were loaded onto the Ni-based nanocomposites’ surface through electrostatic adsorption. Through characterization by transmission electron microscopy (TEM), high resolution TEM (HRTEM) and energy disperse spectroscopy (EDS) mapping, it is found that the AuNPs were well distributed on the surface of Ni-based nanocomposite. Cyclic voltammetric (CV) study showed the electrocatalytic activity of Au-Ni nanocomposite was highly improved after loading AuNPs onto it. Amperometric study demonstrated that the Au-Ni nanocomposites modified glassy carbon electrode (GCE) exhibited a high sensitivity of 2133.5 mA M−1 cm−2 and a wide linear range (0.4–900 μM) toward the oxidation of glucose with a detection limit as low as 0.1 μM. Moreover, the reproducibility, selectivity and stability of the sensor all exhibited outstanding performance. We applied the as-fabricated high performance sensor to measure the glucose levels in human serum and obtained satisfactory results. It is believed that AuNPs decorated Ni MOF/Ni/NiO nanocomposite provides a new platform for developing highly performance electrochemical sensors in practical applications.

Ni and NiO Nanoparticles Decorated Metal-Organic Framework Nanosheets: Facile Synthesis and High-Performance Nonenzymatic Glucose Detection in Human Serum.

Ni-MOF (metal-organic framework)/Ni/NiO/carbon frame nanocomposite was formed by combing Ni and NiO nanoparticles and a C frame with Ni-MOF using an efficient one-step calcination method. The morphology and structure of Ni-MOF/Ni/NiO/C nanocomposite were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and energy disperse spectroscopy (EDS) mapping. Ni-MOF/Ni/NiO/C nanocomposites were immobilized onto glassy carbon electrodes (GCEs) with Nafion film to construct high-performance nonenzymatic glucose and H2O2 electrochemical sensors. Cyclic voltammetric (CV) study showed Ni-MOF/Ni/NiO/C nanocomposite displayed better electrocatalytic activity toward glucose oxidation as compared to Ni-MOF. Amperometric study indicated the glucose sensor displayed high performance, offering a low detection limit (0.8 μM), a high sensitivity of 367.45 mA M-1 cm-2, and a wide linear range (from 4 to 5664 μM). Importantly, good reproducibility, long-time stability, and excellent selectivity were obtained within the as-fabricated glucose sensor. Furthermore, the constructed high-performance sensor was utilized to monitor the glucose levels in human serum, and satisfactory results were obtained. It demonstrated the Ni-MOF/Ni/NiO/C nanocomposite can be used as a good electrochemical sensing material in practical biological applications.

Sensitive fluorescent detection of H2O2 and glucose in human serum based on inner filter effect of squaric acid-iron(III) on the fluorescence of upconversion nanoparticle

Diabetes mellitus is an epidemic disease that it has became a worldwide public health problem. Thus, blood glucose monitoring has attracted extensive attention. Here, we report a nanosensor based on inner filter effect (IFE) between upconversion nanoparticles (UCNPs) and squaric acid (SQA)-iron(III) for the highly sensitive and selective detection of glucose levels in human serum. In this assay, GOx-catalyzed oxidization of glucose produces gluconic acid and hydrogen peroxide (H2O2). The latter can catalytically oxidize iron(II) to iron(III) which can rapidly (<1min) coordinate with the SQA to produce (SQA)-iron(III). The absorption band of (SQA)-iron(III) largely covered the emission band of UCNPs, resulting the fluorescence emission of UCNPs was effectively quenched. Therefore, the glucose can be monitored based on the formation of SQA-iron(III). Under the optimal condition, the fluorescence quenching efficiency shows a good linear response to glucose concentration in the ranges of 7–340μmol/L with a detection limit of 2.3μmol/L. The developed method has been further applied to monitor glucose levels in human serum with satisfactory results. Compared with other fluorescence methods, current method displayed high sensitivity and signal-to-noise ratio. Meanwhile, this nanosystem is also generalizable and can be easily expanded to the detection of various H2O2-involved analytes.

MnO2-Nanosheet-Modified Upconversion Nanosystem for Sensitive Turn-On Fluorescence Detection of H2O2 and Glucose in Blood.

Blood glucose monitoring has attracted extensive attention because diabetes mellitus is a worldwide public health problem. Here, we reported an upconversion fluorescence detection method based on manganese dioxide (MnO2)-nanosheet-modified upconversion nanoparticles (UCNPs) for rapid, sensitive detection of glucose levels in human serum and whole blood. In this strategy, MnO2 nanosheets on the UCNP surface serve as a quencher. UCNP fluorescence can make a recovery by the addition of H2O2, which can reduce MnO2 to Mn(2+), and the glucose can thus be monitored based on the enzymatic conversion of glucose by glucose oxidase to generate H2O2. Because of the nonautofluorescent assays offered by UCNPs, the developed method has been applied to monitor glucose levels in human serum and whole blood samples with satisfactory results. The proposed approach holds great potential for diabetes mellitus research and clinical diagnosis. Meanwhile, this nanosystem is also generalizable and can be easily expanded to the detection of various H2O2-involved analytes.

Complex permittivity characterization of serum with an air-bridge enhanced capacitor for quantifiable detection of glucose

We proposed the complex permittivity characterization of serum sample on an air-bridge enhanced capacitor for the mediator-free glucose sensor in the radio frequency of 7.37 GHz. An air-bridge enhanced capacitor with integrated passive device process on a gallium arsenide substrate was implemented for the design, fabrication, and testing to enable effective quantifiable detection of glucose levels in human serum. The decomposition parameters such as complex permittivity, air-bridge capacitance, phase and correlation coefficient were extracted from the measured S-parameter. A high detectable resolution of 0.61 MHz/mg dl−1 and 3.4 pF/mg dl−1 for ten different subjects of serum in the concentration range of 65 to 245 mg/dl at a minimum glucose concentration of 65 mg/dl was realized. The findings support the development of resonance-based sensing by the characterization of complex permittivity with excellent linearity having a correlation coefficient of 0.9979, short assay time of 40 s, limit of quantization of 29.37 mg/dl, and minimum detectable glucose level of about 9.69 mg/dl.

A reusable robust radio frequency biosensor using microwave resonator by integrated passive device technology for quantitative detection of glucose level.

A reusable robust radio frequency (RF) biosensor with a rectangular meandered line (RML) resonator on a gallium arsenide substrate by integrated passive device (IPD) technology was designed, fabricated and tested to enable the real-time identification of the glucose level in human serum. The air-bridge structure fabricated by an IPD technology was applied to the RML resonator to improve its sensitivity by increasing the magnitude of the return loss (S21). The resonance behaviour, based on S21 characteristics of the biosensor, was analysed at 9.20 GHz with human serum containing different glucose concentration ranging from 148-268 mg dl(-1), 105-225 mg dl(-1) and at a deionised (D) water glucose concentration in the range of 25- 500 mg dl(-1) for seven different samples. A calibration analysis was performed for the human serum from two different subjects and for D-glucose at a response time of 60 s; the reproducibility, the minimum shift in resonance frequency and the long-term stability of the signal were investigated. The feature characteristics based on the resonance concept after the use of serum as an analyte are modelled as an inductor, capacitor and resistor. The findings support the development of resonance-based sensing with an excellent sensitivity of 1.08 MHz per 1 mg dl(-1), a detection limit of 8.01 mg dl(-1), and a limit of quantisation of 24.30 mg dl(-1).

Au-nanocluster emission based glucose sensing

Fabrication of a glucose biosensor based on Au-cluster emission quenching in the UV region is reported. The glucose biosensor is highly sensitive to β-d-glucose in 2.5–25.0mM range as confirmed from a linear calibration plot between Au-cluster colloid emission intensity as a function of β-d-glucose concentration. The interaction of β-d-glucose with l-cysteine capped Au cluster colloids has been confirmed from their Fourier transformed infrared spectroscopy (FTIR) measurements. It has been found that the biomolecules present in the serum such as ascorbic and uric acids, proteins and peptides do not interfere and affect in glucose estimation as confirmed from their absorption and fluorescence (FL) emission measurements. Practical utility of this sensor based on FL quenching method has been demonstrated by estimating the glucose level in human serum that includes diabetes and the data were found to be comparable or more accurate than those of the pathological data obtained from a local hospital. In addition, this biosensor is useful to detect glucose level over a wide range with sensor response time of the order of nano to picoseconds that is emission lifetime of Au clusters.

Glucose sensing electrodes based on a poly(3,4-ethylenedioxythiophene)/Prussian blue bilayer and multi-walled carbon nanotubes

Here we report a new glucose sensing electrode based on a poly(3,4-ethylenedioxythiophene) (PEDOT)/Prussian blue (PB) bilayer and multi-walled carbon nanotubes (CNT). The bilayer was prepared on a flexible screen-printed carbon electrode (SPCE) by sequential electrodeposition. The inner PB layer was electrodeposited first for detecting H2O2 from glucose oxidation; the outer PEDOT layer was electropolymerized on a baked or an unbaked PB film to entrap glucose oxidase (GOD). It was observed that the stability of PB in phosphate buffered saline (pH 7.4) was attained by post-deposition bake at 100°C and the outer PEDOT layer both. In addition, a baked PB film enhanced the subsequent PEDOT growth and the corresponding GOD entrapment. As a result, the bilayer enzyme electrode showed highly resolved and reproducible signals (R.S.D.=2.54%) to glucose samples from 100μM to 1M during a flow-injection analysis (FIA) at −0.1V vs. Ag/AgCl. The sensitivity of the linear range (1–10mM) was 2.67μAcm−2mM−1. Moreover, the electrode retained ca. 82% of the original response after 1-month storage in PBS, pH 6.0 at 4°C and could determine the glucose level in human serum precisely. Besides, it was found that CNT incorporation could further improve the sensitivity and could achieve μM-range glucose detection.

Amperometric Biosensor Coupled to Capillary Electrophoresis for Glucose Determination

A novel glucose biosensor has been fabricated and employed as the amperometric detector of a capillary electrophoresis (CE) system. (±)-1-Ferrocenylethylamine and chitosan were successively modified on a 500-µm diameter disc platinum electrode by dip-coating. The modified electrode was subsequently immersed in glucose oxidase (GOx) solution to entrap the enzyme in the chitosan membrane. The primary amino groups of 1-ferrocenylethylamine, GOx, and chitosan were cross-linked by glutaraldehyde to obtain a biosensing membrane so as to reduce leaching of 1-ferrocenylethylamine and GOx. The electrochemical behavior of the target biosensor was investigated. It was demonstrated that the investigated biosensor features fast response, high stability, long lifetime, and ideal compatibility with the CE system. When CE was employed to introduce a glucose plug into the surface of the biosensor, the current response was linear to the glucose concentration in the range of 0.0025 to 2.5 mM with a detection limit of 1.2 µM (S/N = 3) at a working potential of +0.6 V (vs. SCE). The CE-biosensor system was applied to the determination of the glucose level in human serum. The results were satisfactory and in good agreement with the hospital assay results.