Non-enzymatic Glucose Biosensor Based on Cu/SWNTs Composite Film Fabricated by One-step Electrodeposition

Based on the adsorption of copper ions on single-walled carbon nanotubes（SWNTs） in electrolyte, Cu/SWNTs nanocomposite film was initially prepared on indium-doped tin oxide（ITO） substrate by one-step electrodeposition. This method may provide a versatile and facile pathway to fabricate other SWNTs-supported metal composite films. Electrochemical experiments revealed that the obtained Cu/SWNTs/ITO electrode offered an excellent electrocatalytic activity towards the oxidation of glucose and could be applied to the construction of non-enzymatic glucose biosensor. The linear range of the sensor was 1.0×10–6 to 6.0×10–4 mol/L and the response time was within 2 s. Particularly, its sensitivity reached as high as 1434.67 μA？L？mmol–1？cm–2, which was superior to any other non-enzymatic glucose biosensor based on copper-carbon nanotubes electrode reported previously.

Amperometric glucose biosensor based on gold nanorods and chitosan comodified Au electrode

Au nanorods were prepared by a seeding growth approach and used in fabricating the nanorod-enhancing glucose biosensor. The high affinity of chitosan for Au nanorods associated with its amino groups resulted in the formation of a layer of Au nanorods on the surface of Au electrode. It served as an intermediator to retain high efficient and stable immobilization of the enzyme. The performance of biosensors was investigated by cyclic voltammetry （CV）, in the presence of artificial redox mediator, ferrocenecarboxaldehyde. The biosensor had a fast response to glucose, and the response time was less than 10 s. The results indicated that the gold nanorods could enhance the current response to glucose. The detection limits of glucose can reach 10 mM, and the Michaelis-Menten constant Km^app is 13.62 mM.

A ferrocene-mediated anti-interfering glucose biosensor based on glutin and cellulose acetate

A ferrocene-mediated glucose biosensor removing interference of ascorbic acid and uric acid was developed by coating of ferrocene, glutin and cellulose acetate on screen-printed gold electrode surface. The resuhs show that it can detect glucose sensitively in the presence of uric acid and ascorbic acid, and also suppress the leakage velocity of fcrrocene. Compared to the currents of the pretreated electrode, it decreases the current of uric acid and ascorbic acid by 99.4% and 98.8% at 400 mV, respectively, with a dynamic range of 0 - 30 mM for glucose, sensitivity of 30.73 nA/mM, response time of 10 s, and correlation coefficient of 0.998 8.

Construction of Amperometric Glucose Biosensor based on In-situ Fabricated Hierarchical Mesomacroporous SiO2 Modified Au Film Electrodes

Gold nanoparticles（GNPs） modified hierarchical meso-macroporous（HMMP） SiO2 layer on the surface of Au film electrode was developed as a novel enzyme immobilization matrix for biosensors construction.HMMP SiO2-Au bilayer film electrodes were in-situ fabricated with magnetron sputtering process and templating method.The as-prepared HMMP SiO2 films were characterized by SEM,TEM,and cyclic voltammetry（CV）.The modified layer of HMMP SiO2 has interconnected pore channels,and the sizes of macropores and mesopores are about 330 nm and 9 nm,respectively.The HMMP SiO2 modified gold film electrodes not only have no diffusion barrier for electrochemical probes,but also exhibit good electrochemical properties.In addition,the activity and stability of the immobilized enzyme can be commendably retained in HMMP SiO2.The biosensor exhibits an excellent bioelectrocatalytic response to glucose with a linear range of 1.0×10-4M-1.0×10-2M,high sensitivity of 18.0 μA·m M-1·cm-2,as well as good reproducibility and stability.

Microelectrode glucose biosensor based on nanoporous platinum/graphene oxide nanostructure for rapid glucose detection of tomato and cucumber fruits

A microelectrode glucose biosensor based on a three-dimensional hybrid nanoporous platinum/graphene oxide nanostructure was developed for rapid glucose detection of tomato and cucumber fruits.The nanostructure was fabricated by a two-step modification method on a microelectrode for loading a larger amount of glucose oxidase.The nanoporous structure was prepared on the surface of the platinum microelectrode by electrochemical etching,and then graphene oxide was deposited on the prepared nanoporous electrode by electrochemical deposition.The nanoporous platinum/graphene oxide nanostructure had the advantage of improving the effective surface area of the electrode and the loading quantity of glucose oxidase.As a result,the biosensor achieved a wide range of 0.1-20.0 mmol/L in glucose detection,which had the ability to accurately detect the glucose content.It was found that the three-dimensional hybrid nanostructure on the electrode surface realized the rapid direct electrochemistry of glucose oxidase.Therefore,the biosensor achieved high glucose detection sensitivity 11.64μA·L/(mmol.cm^(2)),low detection limit(13μmol/L)and rapid response time(reaching 95%steady-state response within 3 s),when calibrating in glucose standard solution.In agricultural application,the as-prepared biosensor was employed to detect the glucose concentration of tomato and cucumber samples.The results showed that the relative deviation of this method was less than 5%when compared with that of high-performance liquid chromatography,implying high accuracy of the presented biosensor in glucose detection in plants.

A mediator-free self-powered glucose biosensor based on a hybrid glucose/MnO_(2) enzymatic biofuel cell

Self-powered glucose biosensor(SPGB)is of great interest due to the advantages including single configuration,good stability and particularly no need of external power sources.Herein,a mediator-free SPGB with high sensitivity and good selectivity is constructed based on a hybrid enzymatic biofuel cell(EBFC)composed of a glucose oxidase/cobalt phthalocyanine/1-pyrenebutyric acid/buckypaper(GOD/CoPc/PBA/BP)bioanode and a MnO_(2)/PBA/BP capacitive cathode.The efficient electron transfer from GOD to electrodes is achieved successfully through the anode oxidation of hydrogen peroxide(H_(2)O_(2)),one nature product of glucose oxidation catalyzed by GOD,thus avoiding the potential drawbacks posed by the use of redox mediators.CoPc servers as an efficient catalyst to lower the anode potential required by the reaction of H_(2)O_(2) to 0.17 V.The MnO_(2)/PBA/BP capacitive cathode is utilized because it can not only provide a high discharge potential and adequate capacitance to match the bioanode well,but also exhibit no potential interference to the anodic reaction.The concentration of glucose can be detected simply by measuring the output of the SPGB and a wide linear detection range from 0.5 to 8 mM has been obtained with high sensitivities of 48.66 and 32.12μA·cm^(−2)·mM^(−1) with and without stirring,respectively.The recoveries of glucose in grape juice and human serum are in the range from 99.5%to 101.2%with the relative standard deviation(RSD)less than 8%,indicating the good promise of the SPGB in sensing glucose in real samples.

Highly stable,stretchable,and transparent electrodes based on dualheaded Ag@Au core-sheath nanomatchsticks for non-enzymatic glucose biosensor

Stretchable and transparent electrodes(STEs)based on silver nanowires(AgNWs)have garnered considerable attention due to their unique optoelectronic features.However,the low oxidation resistance of AgNWs severely limits the reliability and durability of devices based on such STEs.The present work reports a type of core-sheath silver@gold nanowires(Ag@Au NWs)with a morphology resembling dual-headed matchsticks and an average Au sheath thickness of 2.5 nm.By starting with such Ag@Au NWs,STEs with an optical transmittance of 78.7%,a haze of 13.0%,a sheet resistance of 13.5Ω·sq.−1,and a maximum tensile strain of 240%can be formed with the aid of capillary-force-induced welding.The resultant STEs exhibit exceptional oxidation resistance,high-temperature resistance,and chemical/electrochemical stability owing to the conformal and dense Au sheath.Furthermore,non-enzymatic glucose biosensors are fabricated employing the Ag@Au NW STEs.The electrocatalytic oxidation currents are proportional to glucose concentrations with a high sensitivity of 967μA·mM−1·cm−2 and a detection limit of 125μM over a detection range of 0.6 to 16 mM.Additionally,the biosensors demonstrate an appealing robustness and antiinterference characteristics,high repeatability,and great stability that make them adequate for practical use.

Glucose biosensor based on new carbon nanotube–gold–titania nano-composites modifed glassy carbon electrode

In this paper, a novel biosensor was prepared by immobilizing glucose oxidase （GOx） on carbon nanotube-gold-titania nanocomposites （CNT/Au/TiO2） modified glassy carbon electrode （GCE）. SEM was initially used to investigate the surface morphology of CNT/Au/TiO2 nanocomposites modified GCE, indicating the formation of the nano-porous structure which could readily facilitate the attachment of GOx on the electrode surface. Cyclic voltammogram （CV） and electrochemical impedance spectrum （EIS） were further utilized to explore relevant electrochemical activity on CNT]Au/TiO2 nanocomposites modified GCE. The observations demonstrated that the immobilized GOx could efficiently execute its bioelectrocatalytic activity for the oxidation of glucose. The biosensor exhibited a wider linearity range from 0.1 mmol L-1 to 8 mmol L^-1 glucose with a detection limit of 0.077 mmol L^- 1.

Photoelectrochemical glucose biosensor incorporating CdS nanoparticles

A novel photoelectrochemical biosensor incorporating nanosized CdS semiconductor crystals with enzyme to enhance photochemical reaction has been investigated. CdS nanoparticles were synthesized by using dendrimer PAMAM as inner templates. The CdS nanoparticles and glucose oxidase （GOD） were immobilized on Pt electrode via layer-by-layer （LbL） technique to fabricate a biological-inorganic hybrid system. Under ultraviolet light, the photo-effect of the CdS nanoparticles showed enhancement of the biosensor to detect glucose. Pt nanoparticles were mixed into the Nation film to immobilize the CdS/enzyme composites and to improve the charge transfer of the hybrid. Experimental results demonstrate the desirable characteristics of this biosensing system, e,g. a sensitivity of 1.83 μA/（mM cm^2）, lower detection limit （1 μM）, and acceptable reproducibility and stability,

Ceramic Carbon/Polypyrrole Materials for the Construction of Bienzymatic Amperometric Biosensor for Glucose

A novel amperometric glucose biosensor was constructed by electrochemical formation of a polypyrrole (PPy) membrane in the presence of glucose oxidase (GOD) on the surface of a horseradish peroxidase (HRP) modified ferrocenecarboxylic acid (FCA) mediated sol-gel derived ceramic carbon electrode. The amperometric detection of glucose was carried out at +0.16 V (vs. SCE) in 0.1 mol/L phosphate buffer solution (pH 6.9) with a linear response range between 8.0x10(-5) and 1.3x10(-3) mol/L of glucose. The biosensor showed a good suppression of interference and a negligible deviation in the amperometric detection.

Electrochemical biosensor employing PbS colloidal quantum dots/Au nanospheres-modified electrode for ultrasensitive glucose detection

Rapid and accurate detection of glucose is of great significance for diabetic management.Highly sensitive glucose sensors promise to achieve noninvasive detection technology,enabling more convenient and efficient means for large-scale screening and long-term dynamic monitoring of diabetes patients.In this work,we demonstrate a sensitive glucose electrochemical biosensor through the synergetic labelling strategy utilizing PbS colloidal quantum dots(CQDs)and Au nanospheres(AuNSs).The PbS CQDs/AuNSs/glucose oxidase(GOx)mixture could be stably immobilized on the carbon electrode surface via the onestep dip-coating method.The electrochemical biosensor employing PbS CQDs/AuNSs/GOx-modified electrode integrates the functions of specific molecule recognition,signal transduction as well as signal amplification.The sensor is capable of transducing the glucose enzyme-catalyzed reaction into significant current signals,exhibiting a good linear response in the glucose concentration range of 0.1μM-10 mM with the limit of detection being 1.432 nM.

Anti-biofouling strategies for implantable biosensors of continuous glucose monitoring systems

Continuous glucose monitoring(CGM)systems play an increasingly vital role in the glycemic control of patients with diabetes mellitus.However,the immune responses triggered by the implantation of poorly biocompatible sensors have a significant impact on the accuracy and lifetime of CGM systems.In this review,research efforts over the past few years to mitigate the immune responses by enhancing the anti-biofouling ability of sensors are summarized.This review divided these works into active immune engaging strategy and passive immune escape strategy based on their respective mechanisms.In each strategy,the various biocompatible layers on the biosensor surface,such as drug-releasing membranes,hydrogels,hydrophilic membranes,anti-biofouling membranes based on zwitterionic polymers,and bio-mimicking membranes,are described in detail.This review,therefore,provides researchers working on implantable biosensors for CGM systems with vital information,which is likely to aid in the research and development of novel CGM systems with profound anti-biofouling properties.

Ultra-low charge transfer resistance carbons by onepot hydrothermal method for glucose sensing

Hydrothermal carbon （HTC） is typically well- dispersed, but it remains a great challenge for HTC to become conductive. Co-doping with heteroatoms has been confirmed to be an effective strategy to significantly promote the electrical conductivity of carbon. Moreover, there is no simple and green method to construct sensitive HTC based electro- chemical biosensors until now. In this paper, N and S dual-doped carbon （NS-C） with ultra-low charge transfer resistance is easily synthesized from L-cysteine and glucose in a hydrothermal reaction system. The morphology, structural prop- erties and electrochemical properties of the as-prepared NS-C are analyzed. In comparison with the undoped hydrothermal （UC） modified glassy carbon electrode （GCE）, the charge transfer resistance of UC （476 Ω） is ten times the value of NS- C （46 Ω）. The developed biosensor shows a better performance to detect glucose in a wide concentration range （50-2500 μmol L^-1） with the detection limit of 1.77 μmol L^-1 （S/N-3） and a high sensitivity （0.0554 μA cm^-2μmol^-1 L）. The apparent Michaelis-Menten constant value of GCE/NS-C/GOx/nafion modified electrode is 0.769 mmol L^-1, indicating a high affinity of glucose oxidase to glucose. These results demonstrate that the hydrothermal method is an effective way for prepar- ing high electrical conductivity carbon with excellent performances in biosensor application.

Preparation of glucose oxidase electrode containing hydrophobic silica nanoparticles by the sol-gel method

The influences of hydrophobic SiO_2 nanoparticles and the contents of glucose oxidase(GOD) upon the response current of enzyme electrode have been investigated by using the sol-gel method,in which polyvinylbutyryl(PVB)was used as a matrix.The influenoe of enzymatic activity was measured by electrochemical method.Experimental data demonstrated that hydrophobic SiO_2 particles can immobilize enzyme well,providing a good and simple method for preparing high quality GOD biosensor.The mechanism has been discussed.