A novel amperometric glucose biosensor based on layer‐by‐layer (LbL) electrostatic adsorption of glucose oxidase (GOx) and dendrimer‐encapsulated Pt nanoparticles (Pt‐DENs) on multiwalled carbon nanotubes (CNTs) was described. Anionic GOx was immobilized on the negatively charged CNTs surface by alternatively assembling a cationic Pt‐DENs layer and an anionic GOx layer. Transmission electron microscopy images and ζ‐potentials proved the formation of layer‐by‐layer nanostructures on carboxyl‐functionalized CNTs. LbL technique provided a favorable microenvironment to keep the bioactivity of GOx and prevent enzyme molecule leakage. The excellent electrocatalytic activity of CNTs and Pt‐DENs toward H2O2 and special three‐dimensional structure of the enzyme electrode resulted in good characteristics such as a low detection limit of 2.5 μM, a wide linear range of 5 μM–0.65 mM, a short response time (within 5 s), and high sensitivity (30.64 μA mM?1 cm?2) and stability (80% remains after 30 days). 相似文献
Weak polyelectrolytes poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) were assembled into {PAH/PAA}n layer‐by‐layer films on electrodes. The cyclic voltammetry (CV) response of ferrocenecarboxylic acid (Fc(COOH)) at {PAH/PAA}5 film electrodes assembled under the specific condition showed pH‐sensitive “on‐off” switching property. This property was further used to control the electrocatalytic oxidation of glucose by glucose oxidase (GOD) with Fc(COOH) as the electron transfer mediator, so that the pH‐switchable bioelectrocatalysis could be realized. The mechanism of pH‐sensitive behavior of the system was explored and believed to originate from the pH‐dependent structure change of the films. 相似文献
A type of novel electroanalytical sensing nanobiocomposite material was prepared by electropolymerization of pyrrole containing poly(amidoamine) dendrimers‐encapsulated platinum nanoparticles (Pt‐PAMAM), and glucose oxidase (GOx). The Pt nanoparticles encapsulated in PAMAM are nearly monodisperse with an average diameter of 3 nm, and they provide electrical conductivity. Polypyrrole acts as a polymer backbone to give stable and homogeneous cast thin films, and it also defines the electrical conductivity. Both Polypyrrole and PAMAM can provide a favorable microenvironment to keep the bioactivity of enzymes such as glucose oxidase. The homogeneity of GOx/Pt‐PAMAM‐PPy nanobiocomposite films was characterized by atomic force microscopy (AFM). Amperometric biosensors fabricated with these materials were characterized electrochemically using cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and amperometric measurements in the presence of hydrogen peroxide or glucose. All those show the resultant biosensor sensitivity was strongly enhanced within the nanobiocomposite film. The optimized glucose biosensor displayed a sensitivity of 164 μA mM?1 cm?1, a linear range of 0.2 to 600 μM, a detection limit of 10 nM, and a response time of <3 s. 相似文献
A new glucose biosensor design based on glucose oxidase (GOD) immobilized by polypyrrole has been described in this paper. The polymerization of pyrrole was initiated by a hexachloroplatinate which itself was reduced into Pt nanoparticles and thus served as a catalyst for the H2O2 oxidation. Properties of the produced GOD modified electrode were examined and the activity of the entrapped enzyme was determined by basic application on the amperometric detection of glucose. Much better results were found comparatively with the enzyme electrode for which the enzyme was entrapped by the electrochemically polymerized polypyrrole. This kind of technique for Pt nanoparticles deposition can be generalized to many cases where polypyrrole is used. 相似文献
Pt nanoparticles were deposited on mesoporous carbon material CMK-3. Glucose oxidase (GOx) was immobilized in the resulting Pt nanoparticles/mesoporous carbon (Pt/CMK-3) matrix, and then the mixture was cast on a glassy carbon electrode (GCE) using gelatin as a binder. The glucose biosensor exhibited excellent current response to glucose after cross-linking with glutaraldehyde. At 0.6V (vs. SCE) the response current was linear to glucose concentration in the range of 0.04-12.2mM. The response time (time for achieving 95% of the maximum current) was 15s and the detection limit (S/N=3) was 1 microM. The Michaelis-Menten constant (K(m)(app)) and the maximum current density (i(max)) were 10.8 mM and 908 microAcm(-2), respectively. The activation energy of the enzymatic reaction was estimated to be 22.54 kJ mol(-1). The biosensor showed good stability. It achieved the maximum response current at about 52 degrees C and retained 95.1% of its initial response current after being stored for 30 days. In addition, some fabrication and operation parameters for the biosensor were optimized in this work. The biosensor was used to monitor the glucose levels of serum samples after being covered with an extra Nafion film to improve its anti-interferent ability and satisfied results were obtained. 相似文献
A sensitive amperometric glucose biosensor based on platinum nanoparticles (PtNPs) combined aligned carbon nanotubes (ACNTs) electrode was investigated. PtNPs which can enhance the electrocatalytic activity of the electrode for electrooxidating hydrogen peroxide by enzymatic reaction were electrocrystallized on 4‐aminobenzene monolayer‐grafted ACNTs electrode by potential‐step method. These PtNPs combined ACNTs' (PtNPs/ACNTs) surfaces were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The highly dispersed PtNPs on ACNTs can be obtained. The enzyme electrode exhibits excellent response performance to glucose with linear range from 1×10?5–7×10?3 mol L?1 and fast response time within 5 s. Furthermore, this glucose biosensor also has good reproducibility. It is demonstrated that the PtNPs/ACNTs electrode with high electrocatalytic activity is a suitable basic electrode for preparing enzyme electrodes. 相似文献
A novel glucose biosensor was developed based on the immobilization of glucose oxidase (GOx) on reduced graphene oxide incorporated with electrochemically deposited platinum and palladium nanoparticles (PtPdNPs). Reduced graphene oxide (RGO) was more hybridized by chemical and heat treatment. Bimetallic nanoparticles were deposited electrochemically on the RGO surface for potential application of the Pd? Pt alloy in biosensor preparation. The as‐prepared hybrid electrode exhibited high electrocatalytic activities toward H2O2, with a wide linear response range from 0.5 to 8 mM (R2=0.997) and high sensitivity of 814×10?6 A/mMcm2. Furthermore, glucose oxidase with active material was integrated by a simple casting method on the RGO/PdPtNPs surface. The as‐prepared biosensor showed good amperometric response to glucose in the linear range from 2 mM to 12 mM, with a sensitivity of 24×10?6 A/mMcm2, a low detection limit of 0.001 mM, and a short response time (5 s). Moreover, the effect of interference materials, reproducibility and the stability of the sensor were also investigated. 相似文献
A nonenzymatic amperometric sensor for sensitive and selective detection of glucose has been constructed by using highly dispersed Pt nanoparticles supported onto mesoporous carbons (MCs). The Pt nanoparticles/mesoporous carbons (Pt/MCs) composites modified electrode displayed high electrocatalytic activity towards the oxidation of glucose. At an applied potential of 0.1 V, the Pt/MCs electrode has a linear dependence (R=0.996) in the glucose concentration up to 7.5 mM with a sensitivity of 8.52 mA M?1 cm?2. The Pt/MCs electrode has also shown highly resistant toward poisoning by chloride ions and without interference from the oxidation of common interfering species. 相似文献
In this research a novel osmium complex was used as electrocatalyst for electroreduction of oxygen and H2O2 in physiological pH solutions. Electroless deposition at a short period of time (60 s), was used for strong and irreversible adsorption of 1,4,8,12‐tetraazacyclotetradecane osmium(III) chloride (Os(III)LCl2) ClO4 onto single‐walled carbon nanotubes (SWCNTs) modified GC electrode. The modified electrode shows a pair of well defined and reversible redox couple, Os(IV)/Os(III) at wide pH range (1–8). The glucose biosensor was fabricated by covering a thin film of glucose oxidase onto CNTs/Os‐complex modified electrode. The biosensor can be used successfully for selective detection of glucose based on the decreasing of cathodic peak current of oxygen. The fabricated biosensor shows high sensitivity, 826.3 nA μM?1cm?2, low detection limit, 56 nM, fast response time <3 s and wide calibration range 1.0 μM–1.0 mM. The biosensor has been successfully applied to determination of glucose in human plasma. Because of relative low applied potential, the interference from electroactive existing species was minimized, which improved the selectivity of the biosensor. The apparent Michaelis‐Menten constant of GOx on the nanocomposite, 0.91 mM, exhibits excellent bioelectrocatalytic activity of immobilized enzyme toward glucose oxidation. Excellent electrochemical reversibility, high stability, technically simple and possibility of preparation at short period of time are of great advantages of this glucose biosensor. 相似文献
This paper describes a layer‐by‐layer (LBL) self‐assembly process of chitosan (CTS) and gold nanoparticles (Au) on the pretreated negatively charged glassy carbon (GC) electrode to fabricate electrochemistry immunosensor with a nontoxic biomimetic interface, which provided an environment similar to a native system and allowed more freedom in orientation for immobilization of carcinoembryonic antibody (anti‐CEA) to monitor carcinoembryonic antigen (CEA). UV‐vis spectroscope, atomic force microscopy (AFM), and cyclic voltammetric (CV) measurements were used to follow the multilayer film formation. The performance of the biominetic interface and factors influencing the assay system were investigated in detail. The differential pulse voltammetry (DPV) current response is used for the CEA concentration assay. The dynamic range was from 0.50 to 80.00 ng mL?1 with a detection limit of 0.27 ng mL?1 at 3σ. In addition, the experiment results indicate that immobilization described in this proposed method exhibits a good sensitivity, selectivity, and stability. 相似文献
A novel complex material was fabricated by three steps. In the first step, gold nanoparticle (Aunano) was prepared with the method of chemistry and dialysis. In the second step, 4‐aminothiophenol (AT) was encapsulated in the cavity of β‐cyclodextrin and formed inclusion complex, cyclodextrin/4‐aminothiophenol (CD/AT). And then inclusion complex was adsorbed to the surface of Aunano based on the bond of Au‐S interaction. In the last step, a complex material, cyclodextrin/poly(4‐aminothiophenol)‐Au nanoparticles (CD/PAT‐Aunano) was obtained by the polymerizing in the acid solution initiated by chlorauric acid. The CD/PAT‐Aunano has spherical nanostructure with the average diameter of 55 nm. Glucose oxidase (GOx) was anchored with this complex material and direct electrochemistry of GOx was achieved. A couple of stable and well‐defined redox peaks were observed with the formal potential (E0′) of ‐0.488 V (vs. SCE) in a pH 6.98 buffer solution. The GOx modified electrode also exhibited an excellent electrocatalytic activity to the reduction of glucose, a linearity range for determination of glucose is from 0.25 mM to 16.0 mM with a detection limit of 0.09 mM (S/N = 3). This protocol had potential application to fabricate the third‐generation biosensor. 相似文献
Summary: The multilayers of polycation‐based non‐viral DNA nanoparticles and biodegradable poly(L ‐glutamic acid) (PGA) were constructed by a layer‐by‐layer (LbL) technique. Poly(ethyleneimine) (PEI) was used to condense DNA to develop non‐viral DNA nanoparticles. AFM, UV‐visible spectrometry, and TEM measurements revealed that the PEI‐DNA nanoparticles were successfully incorporated into the multilayers. The well‐structured, easily processed multilayers with the non‐viral DNA nanoparticles may provide a novel approach to precisely control the delivery of DNA, which may have great potential for gene therapy applications in tissue engineering, medical implants, etc.
A TEM image of the cross section of a (PGA/PEI‐DNA nanoparticle)20 multilayer. 相似文献
Layer‐by‐layer (LBL) assemblies, which have undergone great progress in the past decades, have been used widely in the construction of electrochemical biosensors. The LBL assemblies provide a strategy to rationally design the properties of immobilized films and enhance the performance of biosensors. The following review focuses on the application of LBL assembly technique on electrochemical enzyme biosensors, immunosensors and DNA sensors. 相似文献
The precursor film was first formed on the Au electrode surface based on the self‐assembly of L ‐cysteine and the adsorption of gold colloidal nanoparticles (nano‐Au). Layer‐by‐layer (LBL) assembly films of toluidine blue (TB) and nano‐Au were fabricated by alternately immersing the electrode with precursor film into the solution of toluidine blue and gold colloid. Cyclic voltammetry (CV) and quartz crystal microbalance (QCM) were adopted to monitor the regular growth of {TB/Au} bilayer films. The successful assembly of {TB/Au}n films brings a new strategy for electrochemical devices to construct layer‐by‐layer assembly films of nanomaterials and low molecular weight materials. In this article, {TB/Au}n films were used as model films to fabricate a mediated H2O2 biosensor based on horseradish peroxidase, which responded rapidly to H2O2 in the linear range from 1.5×10?7 mol/L to 8.6×10?3 mol/L with a detection limit of 7.0×10?8 mol/L. Morphologies of the final assembly films were characterized with scanning probe microscopy (SPM). 相似文献