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Albumin is a vital blood protein responsible for transporting metabolites and drugs throughout the body and serves as a potential biomarker for various medical conditions, including inflammatory, cardiovascular, and renal issues. This report details the fabrication of Ni-metal organic framework/SnS2nanocomposite modified nickel foam electrochemical sensor for highly sensitive and selective non enzymatic detection of albumin in simulated human blood serum samples. Ni-metal organic framework/SnS2nanocomposite was synthesized using solvothermal technique by combining Ni-metal-organic framework (MOF) with conductive SnS2leading to the formation of a highly porous material with reduced toxicity and excellent electrical conductivity. Detailed surface morphology and chemical bonding of the Ni-MOF/SnS2nanocomposite was studied using scanning electron microscopy, transmission electron microscopy, Fourier transform infra-red, and Raman analysis. The Ni-MOF/SnS2nanocomposite coated on Ni foam electrode demonstrated outstanding electrochemical performance, with a low limit of detection (0.44µM) and high sensitivity (1.3µA/pM/cm2) throughout a broad linear range (100 pM-10 mM). The remarkable sensor performance is achieved through the synthesis of a Ni-MOF/SnS2nanocomposite, enhancing electrocatalytic activity for efficient albumin redox reactions. The enhanced performance can be attributed due to the structural porosity of nickel foam and Ni-metal organic framework, which favours increased surface area for albumin interaction. The presence of SnS2shows stability in acidic and neutral solutions due to high surface to volume ratio which in turn improves sensitivity of the sensing material. The sensor exhibited commendable selectivity, maintaining its performance even when exposed to potential interfering substances like glucose, ascorbic acid, K+, Na+, uric acid, and urea. The sensor effectively demonstrates its accuracy in detecting albumin in real samples, showcasing substantial recovery percentages of 105.1%, 110.28%, and 91.16%.
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Estruturas Metalorgânicas , Nanocompostos , Humanos , Estruturas Metalorgânicas/química , Níquel/química , Soro , Eletrodos , Técnicas EletroquímicasRESUMO
Single atom catalysts (SACs) have attracted attention due to their excellent catalysis activity under specific reactions and conditions. However, the low density of SACs greatly limits catalytic performance. The three-dimensional graphene hollow nanospheres (GHSs) with very thin shell structure can be used as excellent carrier materials. Not only can its outer surface be used to anchor metal single atoms, but its inner surface can also provide rich sites. Here, a novel step-by-step assembly strategy is reported to anchor nickel single atoms (Ni SAs) on the inner and outer surfaces of GHSs (Ni SAs/GHSs/Ni SAs), which significantly increases the loading capacity of Ni SAs (4.8 wt%). Compared to conventional materials that only anchor Ni SAs to the outer surface of the carrier (Ni SAs/GHSs), Ni SAs/GHSs/Ni SAs exhibits significantly higher electrocatalytic activity toward glucose oxidation in alkaline media. The sensitivity of Ni SAs/GHSs/Ni SAs/GCE is nearly five times higher than that of Ni SAs/GHSs/GCE. Moreover, the sensor based on Ni SAs/GHSs/Ni SAs can detect glucose in a wide concentration range of 0.8 µM-1.1244 mM with a low detection limit of 0.19 µM (S/N = 3). This study not only provides an effective sensing material for glucose detection, but also opens a new avenue to construct high-density metal SACs.
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A flexible, wearable, non-invasive contact lens sensor utilizing nickel-cobalt metal-organic framework (Ni-Co-MOF) based hydrogel is introduced for urea monitoring in tear samples. The synthesized Ni-Co-MOF hydrogel exhibits a porous structure with interconnected voids, as visualized by Scanning Electron Microscopy (SEM). Detailed structural and vibrational properties of the material were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, and Raman spectroscopy. The developed Ni-Co-MOF hydrogel sensor showcases a detection limit of 0.445 mM for urea within a linear range of 0.5-70 mM. Notably, it demonstrates exceptional selectivity, effectively distinguishing against interfering species like UA, AA, glucose, dopamine, Cl-, K+, Na+, Ca2+, and IgG. The enhanced electrocatalytic performance of the Ni-Co-MOF hydrogel electrode is attributed to the presence of Ni and Co, fostering Ni2+ oxidation on the surface and forming a Co2+ complex that acts as a catalyst for urea oxidation. The fabricated sensor exhibits successful detection and retrieval of urea in simulated tear samples, showcasing promising potential for bioanalytical applications. The binder-free, non-toxic nature of the Ni-Co-MOF hydrogel sensor presents exciting avenues for future utilization in non-enzymatic electrochemical sensing, including applications in wearable devices, point-of-care diagnostics, and personalized healthcare monitoring.
Assuntos
Estruturas Metalorgânicas , Dispositivos Eletrônicos Vestíveis , Níquel/química , Estruturas Metalorgânicas/química , Ureia , Cobalto , HidrogéisRESUMO
Nanorod structures exhibit a high surface-to-volume ratio, enhancing the accessibility of electrolyte ions to the electrode surface and providing an abundance of active sites for improved electrochemical sensing performance. In this study, tetragonal α-MnO2 with a large K+-embedded tunnel structure, directly grown on microfibrous carbon paper to form densely packed nanorod arrays, is investigated as an electrocatalytic material for non-enzymatic glucose sensing. The MnO2 nanorods electrode demonstrates outstanding catalytic activity for glucose oxidation, showcasing a high sensitivity of 143.82 µA cm-2 mM-1 within the linear range from 0.01 to 15 mM, with a limit of detection (LOD) of 0.282 mM specifically for glucose molecules. Importantly, the MnO2 nanorods electrode exhibits excellent selectivity towards glucose over ascorbic acid and uric acid, which is crucial for accurate glucose detection in complex samples. For comparison, a gold electrode shows a lower sensitivity of 52.48 µA cm-2 mM-1 within a linear range from 1 to 10 mM. These findings underscore the superior performance of the MnO2 nanorods electrode in both sensitivity and selectivity, offering significant potential for advancing electrochemical sensors and bioanalytical techniques for glucose monitoring in physiological and clinical settings.
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Técnicas Biossensoriais , Técnicas Eletroquímicas , Eletrodos , Glucose , Compostos de Manganês , Nanotubos , Óxidos , Compostos de Manganês/química , Óxidos/química , Nanotubos/química , Glucose/análise , Glucose/química , Técnicas Eletroquímicas/métodos , Técnicas Biossensoriais/métodos , Técnicas Biossensoriais/instrumentação , Limite de Detecção , Carbono/química , Oxirredução , Papel , Ácido Úrico/análise , Ácido Úrico/química , Catálise , Ácido Ascórbico/química , Ácido Ascórbico/análiseRESUMO
Cholesterol (CH) is a vital diagnostic marker for a variety of diseases, making its detection crucial in biological applications including clinical practice. In this work, we report the synthesis of tin oxide-polyaniline nanocomposite-modified nickel foam (SnO2-PANI/NF) for non-enzymatic detection of CH in simulated human blood serum. SnO2was synthesized via the hydrothermal method, followed by the synthesis of SnO2-PANI nanocomposite throughin situchemical polymerization of aniline using ammonium persulfate as the oxidizing agent. Morphological studies display agglomerated SnO2-PANI, which possess diameters ranging from an average particle size of â¼50 to â¼500 nm, and the XRD analysis revealed the tetragonal structure of the SnO2-PANI nanocomposite. Optimization studies demonstrating the effect of pH and weight percentage are performed to improve the electrocatalytic performance of the sensor. The non-enzymatic SnO2-PANI/NF sensor exhibits a linear range of 1-100µM with a sensitivity of 300µAµM-1/cm-2towards CH sensing and a low limit of detection of 0.25µM (=3 S m-1). SnO2-PANI/NF facilitates the electrooxidation of CH to form cholestenone by accepting electrons generated during the reaction and transferring them to the nickel foam electrode via Fe (III)/Fe (IV) conversion, resulting in an increased electrochemical current response. The SnO2-PANI/NF sensor demonstrated excellent selectivity against interfering species such as Na+, Cl-, K+, glucose, ascorbic acid, and SO42-. The sensor successfully determined the concentration of CH in simulated blood serum samples, demonstrating SnO2-PANI as a potential platform for a variety of electrochemical-based bioanalytical applications.
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Nanocompostos , Níquel , Humanos , Níquel/química , Soro , Nanocompostos/química , Compostos de Anilina/química , ColesterolRESUMO
The non-enzymatic electrochemical sensors are attractive due to their high sensitivity, quick detection, low cost, and simple construction. Hence, in this work, a non-enzymatic biosensor was constructed with NiCo2O4 nanoparticles (~ 82 nm) decorated over Ti2NbC2 nanosheets by an in-situ method. The crystal structure, phase purity, morphology and elemental composition of the synthesized NiCo2O4/Ti2NbC2 nanohybrid was investigated using XRD, Raman and FESEM analysis. The electrocatalytic and electrochemical behaviour of the prepared nanohybrid was investigated using cyclic voltammetry and amperometry analysis. Hybrid of NiCo2O4/Ti2NbC2 produces a biocompatible, electrochemically active surface with enhanced electrical conductivity. The enhanced surface area of NiCo2O4 and superior electrical conductivity of Ti2NbC2 nanosheets helped to develop non-enzymatic electrochemical glucose sensor with enhanced sensitivity (425.6 µA mM-1cm-2), low limit of detection and quick response time that satisfy glucose detection applications. Thus, the developed non-enzymatic electrochemical glucose sensor has excellent electrochemical properties and making it as a strong candidate for the detection of glucose concentration in sweat.
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Técnicas Biossensoriais , Glucose , Glucose/análise , Suor/química , Técnicas Eletroquímicas/métodos , Titânio , Técnicas Biossensoriais/métodos , EletrodosRESUMO
Introducing oxygen-vacancy into the surface of the non-enzymatic sensor is supposed to be an effective way to improve inherently low catalytic activity and specificity of non-enzymatic sensors. In this work, CuO/C was synthesized at different temperatures using metal-organic frameworks as sacrificial templates to receive additional content of oxygen-vacancy. The product with the highest oxygen vacancy was found at 400 °C (named CuO/C-400 °C), which increased catalytically active sites and enhanced the charge-transfer efficiency. The sensing performance was afterward explored by amperometry under an optimal applied potential at 0.5 V (vs. SCE), presenting a broad detection range from 5.0 µM to 25.325 mM (R2 = 0.9998) with a sensitivity of 244.71 µA mM- 1 cm- 2, and a detection limit of 1 µM. Furthermore, the reliability and selectivity of CuO/C-400 °C sensors were extensively explored in the presence of artificial serum/saliva samples with gradient glucose concentrations. The human blood samples were also detected with high recoveries compared with the clinical Hexokinase method. Hence, the prepared CuO/C-400 °C sensor with a broad detection range and high selectivity can be applied for the diabetes diagnosis ex vivo without further dilution for real-time analysis in practical applications.
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Glucose , Oxigênio , Humanos , Temperatura , Reprodutibilidade dos TestesRESUMO
This study reports a facile approach for constructing low-cost and remarkable electroactivity iron vanadate (Fe-V-O) semiconductor material to be used as a photoelectrochemical sensor for dopamine detection. The structure and morphology of the iron vanadate obtained by the Successive Ionic Adsorption and Reaction process were critically characterized, and the photoelectrochemical characterization showed a high photoelectroactivity of the photoanode in visible light irradiation. Under best conditions, dopamine was detected by chronoamperometry at +0.35 V vs. Ag/AgCl, achieving two linear response ranges (between 1.21 and 30.32 µmol L-1, and between 30.32 and 72.77 µmol L-1). The limits of detection and quantification were 0.34 and 1.12 µmol L-1, respectively. Besides, the accuracy of the proposed electrode was assessed by determining dopamine in artificial cerebrospinal fluid, obtaining recovery values ranging from 98.7 to 102.4%. The selectivity was also evaluated by dopamine detection against several interferent species, demonstrating good precision and promising application for the proposed method. Furthermore, DFT-based electronic structure calculations were also conducted to help the interpretation. The dominant dopamine species were determined according to the experimental conditions, and their interaction with the iron vanadate photoanode was proposed. The improved light-induced DOP detection was likewise evaluated regarding the charge transfer process.
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Técnicas Biossensoriais , Dopamina , Técnicas Biossensoriais/métodos , Dopamina/química , Técnicas Eletroquímicas/métodos , Eletrodos , Ferro , Luz , Limite de Detecção , VanadatosRESUMO
In this paper, a non-enzymatic glucose sensor was developed based on a g-C3N4/NiO/CuO nanocomposite immobilized on a glassy carbon electrode (GCE). Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) were utilized for the characterization of the synthesized g-C3N4/NiO/CuO nanocomposite. The electrocatalytic activity of the nanocomposite was investigated by cyclic voltammetry, and the amperometric technique was applied for monitoring glucose. The g-C3N4/NiO/CuO/GCE exhibited better electrocatalytic performance than g-C3N4/GCE, g-C3N4/CuO/GCE and g-C3N4/NiO/GCE. Under optimized conditions, the proposed sensor offered a linearity ranging from 0.4⯵M to 8.5â¯mM with a detection limit of 0.1⯵M and a sensitivity of 362.12⯵Aâ¯mM-1â¯cm-2. The constructed sensor displayed favorable reproducibility, outstanding selectivity, and long-term performance. These results reveal that the sensor is a promising candidate for blood glucose sensing.
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Técnicas Biossensoriais/métodos , Glicemia/análise , Cobre/química , Técnicas Eletroquímicas/métodos , Grafite/química , Nanocompostos/química , Níquel/química , Compostos de Nitrogênio/química , Carbono/química , Catálise , Espectroscopia Dielétrica , Eletrodos , Vidro/química , Humanos , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Nanocompostos/ultraestrutura , Oxirredução , Reprodutibilidade dos Testes , Espectrometria por Raios X , Difração de Raios XRESUMO
Polyaniline, as a kind of conductive polymer with commercial application prospects, is still under researches in its synthesis and applications. In this work, polyaniline was fabricated on flexible substrates including carbon cloths and polyethylene naphthalate byin situelectropolymerization method. The synthesized flexible electrodes were characterized by scanning electron microscopy, High resolution transmission electron microscope, atomic force microscope, Fourier transform infrared, x-ray diffraction, and x-ray photoelectron spectroscopy. Owing to the conductivity and the reversible redox property, the polyaniline/carbon cloth electrodes show excellent properties such as decent supercapacitor performance and good detection capability toward ascorbic acid. As supercapacitors, the electrodes exhibit a specific capacitance as high as 776 F g-1at a current density of 1 A g-1and a long cycle life of 20 000 times in the three-electrode system. As ascorbic acid sensors, the flexible electrodes demonstrate stable response to ascorbic acid in the range of 1-3000µM with an outstanding sensitivity (4228µA mM-1cm-2), low detection limit (1µM), and a fast response time. This work holds promise for high-performance and low-cost flexible electrodes for both supercapacitors and non-enzymatic ascorbic acid sensors, and may inspire inventions of self-powered electrochemical sensor.
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Non-enzymatic electrochemical sensors possess superior stability and affordability in comparison to natural enzyme-based counterparts. A large variety of nanomaterials have been introduced as enzyme mimicking with appreciable sensitivity and detection limit for various analytes of which glucose and H2O2 have been mostly investigated. The nanomaterials made from noble metal, non-noble metal, and metal composites, as well as carbon and their derivatives in various architectures, have been extensively proposed over the past years. Three-dimensional (3D) transducers especially realized from the hybrids of carbon nanomaterials either with metal-based nanocatalysts or heteroatom dopants are favorable owing to low cost, good electrical conductivity, and stability. In this critical review, we evaluate the current strategies to create such nanomaterials to serve as non-enzymatic transducers. Laser writing has emerged as a powerful tool for the next generation of devices owing to their low cost and resultant remarkable performance that are highly attractive to non-enzymatic transducers. So far, only few works have been reported, but in the coming years, more and more research on this topic is foreseeable.
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Unique Ni2CoS4-carbon nanofiber (CNF) composite nanostructures were fabricated using a simple electrospinning-assisted hydrothermal route and used for the rapid and accurate electrochemical oxidation of glucose in real samples at the trace level. Electrochemical impedance spectroscopy and cyclic voltammetry of unmodified and modified electrodes revealed low charge-transfer resistance and the excellent electrocatalytic sensing of glucose when using the Ni2CoS4-CNF at a low potential due to the combined benefits of the highly conductive Ni2Co2S4 anchored to the large surface area of the CNFs. Amperometric analysis of the fabricated sensor has shown an extremely low limit of detection (0.25 nM) and a large linear range (5-70 nM) for glucose at a working potential of 0.54 V (vs. Hg/HgO). The practicability of the Ni2CoS4-CNF for use in glucose determination was tested withl human saliva, blood plasma, and fruit juice samples. The Ni2CoS4-CNF/GCE showed acceptable recovery values for human saliva (99.1-100.8%), blood plasma (98.6-101.5%), and fruit juice (95.1-105.7%) samples. The proposed sensor also exhibited outstanding electroanalytical characteristics for glucose oxidation in these samples, including reusability, repeatability, and interference resistance, even in the presence of other biological substances and organic and inorganic metal ions.
Assuntos
Glicemia/análise , Técnicas Eletroquímicas/métodos , Nanocompostos/química , Nanofibras/química , Glicemia/química , Carbono/química , Cobalto/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Sucos de Frutas e Vegetais/análise , Humanos , Limite de Detecção , Níquel/química , Oxirredução , Reprodutibilidade dos Testes , Saliva/química , Sulfetos/químicaRESUMO
Copper-doped zinc oxide nanoparticles (NPs) CuxZn1-xO (x = 0, 0.01, 0.02, 0.03, and 0.04) were synthesized via a sol-gel process and used as an active electrode material to fabricate a non-enzymatic electrochemical sensor for the detection of glucose. Their structure, composition, and chemical properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) and Raman spectroscopies, and zeta potential measurements. The electrochemical characterization of the sensors was studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Cu doping was shown to improve the electrocatalytic activity for the oxidation of glucose, which resulted from the accelerated electron transfer and greatly improved electrochemical conductivity. The experimental conditions for the detection of glucose were optimized: a linear dependence between the glucose concentration and current intensity was established in the range from 1 nM to 100 µM with a limit of detection of 0.7 nM. The proposed sensor exhibited high selectivity for glucose in the presence of various interfering species. The developed sensor was also successfully tested for the detection of glucose in human serum samples.
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Técnicas Biossensoriais/métodos , Glicemia/análise , Cobre/química , Técnicas Eletroquímicas/métodos , Eletrodos , Nanopartículas/química , Óxido de Zinco/química , Humanos , OxirreduçãoRESUMO
In this work, a novel manganese dioxide-graphene nanosheets (MnO2-GNSs) composite was synthesized by a facile one-step hydrothermal method, in which manganese dioxide (MnO2) was fabricated by hydrothermal reduction of KMnO4 with GNSs. The structure and morphology of MnO2-GNSs composite were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS). A sensitive non-enzymatic electrochemical sensor based on MnO2-GNSs composite for the detection of low concentration hydrogen peroxide (H2O2) was fabricated. The electrochemical properties of MnO2-GNSs composite modified glassy carbon electrode (MnO2-GNSs/GCE) were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry. The observations confirmed that the fabricated sensor exhibited high electrocatalytic activity for oxidation of H2O2 owing to the catalytic ability of MnO2 particles and the conductivity of GNSs. Under the optimum conditions, the calibration curve was linear for the amperometric response versus H2O2 concentration over the range 0.5-350 µM with a low detection limit of 0.19 µM (S/N = 3) and high sensitivity of 422.10 µA mM-1 cm-2. The determination and quantitative analysis of H2O2 in antiseptic solution on MnO2-GNSs/GCE exhibited percent recovery of 96.50%-101.22% with relative standard deviation (RSD) of 1.48%-4.47%. The developed MnO2-GNSs/GCE might be a promising platform for the practical detection of H2O2 due to its prominent properties including excellent reproducibility, good anti-interference and repeatability.
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Técnicas Eletroquímicas/métodos , Grafite/química , Peróxido de Hidrogênio/análise , Compostos de Manganês/química , Modelos Químicos , Óxidos/química , Carbono/química , Catálise , Espectroscopia Dielétrica , Eletrodos , Limite de Detecção , Reprodutibilidade dos TestesRESUMO
ZnO nanorods (NRs) synthesized by a hydrothermal method and decorated with Au nanoparticles (NPs) were used for fluorescent non-enzymatic glucose detection. The detection is based on the photoluminescence (PL) quenching of ZnO NRs/Au NPs (at 382 nm under 325 nm excitation) exposed to glucose. The sensor exhibits a high sensitivity of (22 ± 2) % mM-1 (defined as percentage change of the PL peak intensity per mM) and a limit of detection (LOD) as low as 0.01 mM, along with an excellent selectivity and a short response time (less than 5 s). In comparison with a fluorescent non-enzymatic ZnO nanostructure-based glucose sensor, the addition of Au NPs significantly enhances the sensitivity. This is attributed to the surface plasmon resonance, which increases not only the photoluminescence intensity but also the photo-oxidation property of the ZnO NRs. Thus, ZnO NRs/Au NPs can act as an efficient photocatalyst for glucose detection. Most importantly, the probe is applicable to glucose detection in human blood serum. The outstanding performance of the material and its cost-effectiveness allow for potential application in single-use, noninvasive glucose devices.Graphical abstract A sensitive non-enzymatic fluorescent glucose probe-based ZnO nanorod decorated with Au nanoparticles.
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Técnicas Biossensoriais/métodos , Glucose/química , Ouro/química , Nanopartículas Metálicas/química , Nanotubos/química , Óxido de Zinco/química , HumanosRESUMO
A novel hybrid with three-dimensional (3D) hierarchical CuS@Pd core-shell cauliflowers decorated on nitrogen-doped reduced graphene oxide (CuS@Pd/N-RGO) has been prepared by a facile wet-chemical route without utilizing any template molecules and surfactants. The characterization results reveal that the 3D flower-like structure of CuS "core" is composed of interconnecting nanoplates, which is conductive to the loading of Pd nanoparticles' "shell" and results in the robust interaction between the core and shell for the formation of CuS@Pd cauliflowers. Anchoring such appealing CuS@Pd cauliflowers on the two-dimensional N-RGO can efficaciously inhibit the aggregation of CuS@Pd cauliflowers and accelerate the kinetics of xanthine oxidation. Benefiting from the multi-functional properties and unique morphology, the sensor constructed by CuS@Pd/N-RGO exhibits excellent performance for non-enzymatic detection of xanthine including a wide detection range of 0.7-200.0 µM (0.94 V vs. SCE), a low detection limit of 28 nM (S/N = 3), high reproducibility (relative standard deviation (RSD) = 4.1%), and commendable stability (retained 90% of the initial electrochemical responses after storage for 30 days), which is amongst the best of various electrochemical sensors reported for xanthine assays till date. Reliable and satisfying recoveries (95-105%, RSD ≤ 4.1%) are achieved for xanthine detection in real samples. The inspiring results make the uniquely structural CuS@Pd/N-RGO greatly promising in non-enzymatic electrochemical sensing applications. Graphical abstract A high-performance non-enzymatic xanthine sensor has been constructed by the three-dimensional hierarchical CuS@Pd core-shell cauliflowers decorated on nitrogen-doped reduced graphene oxide.
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Grafite/química , Nanopartículas Metálicas/química , Xantina/análise , Animais , Catálise , Galinhas , Cobre/química , Técnicas Eletroquímicas , Humanos , Cinética , Limite de Detecção , Nitrogênio/química , Oxirredução , Paládio/química , Reprodutibilidade dos Testes , Xantina/sangue , Xantina/química , Xantina/urinaRESUMO
A nonenzymatic electrochemical sensor is described for the prostate cancer biomarker sarcosine (Sar). Riboflavin was employed to mimic the active center of the enzyme sarcosine oxidase for constructing the biomimetic sensor. The use of riboflavon (Rf) avoids the disadvantages of an enzymatic sensor, such as high cost and poor stability. A glassy carbon electrode (GCE) was modified with a graphene-chitosan (GR) composite and further modified with gold-platinum bimetallic nanoparticles in a polypyrrole (PPy) matrix in order to enhance the catalytic activity of the enzyme mimic. Finally, Rf was electrodeposited on the surface of the AuPt-PPy/GR-modified GCE. Under optimized conditions, the GCE provided high sensitivity and selectivity for Sar at around 0.61 V. Response covers the 2.5-600 µM concentration range, and the detection limit is 0.68 µM. The method was successfully applied to the determination of Sar in spiked urine with 98.0%-103.2% recovery. Graphical abstract Schematic presentation of the fabrication of the Rf/AuPt-PPy/GR/GCE surface and the measurement principle by differential pulse voltammetry (DPV).
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Biomarcadores Tumorais/urina , Materiais Biomiméticos , Sarcosina/urina , Técnicas Biossensoriais , Quitosana/química , Técnicas Eletroquímicas , Eletrodos , Ouro/química , Grafite/química , Humanos , Limite de Detecção , Masculino , Nanopartículas Metálicas/química , Tamanho da Partícula , Platina/química , Neoplasias da Próstata/diagnóstico , Pirróis/química , Riboflavina/química , Sarcosina Oxidase , Propriedades de SuperfícieRESUMO
Gold nanobipyramids were synthesized by a seed-mediated growth method and then supported by multi-walled carbon nanotubes (denoted as AuNBP/MWCNTs). The electrocatalytic activity of the AuNBP/MWCNTs on a glassy carbon electrode (GCE) towards direct glucose oxidation and hydrogen peroxide reduction was superior to that of AuNBPs and MWCNTs. The modified GCE, operated at a typical working voltage of +0.15 V (vs. SCE) and in 0.1 M NaOH solution, exhibits a linear response in the 10 µM to 36.7 mM glucose concentration range with a 3.0 µM detection limit (at S/N = 3) and a sensitivity of 101.2 µA mM-1 cm-2. It also demonstrates good sensitivity towards hydrogen peroxide in at pH 7 solution at a working potential of -0.50 V (vs. SCE), with a linear response range from 5.0 µM to 47.3 mM, a sensitivity of 170.6 µA mM-1 cm-2 and a detection limit of 1.5 µM. Graphical abstract A electrochemical sensing platform based on the use of gold nanobipyramids and multi-walled carbon nanotubes nanocomposites (AuNBP/MWCNTs) is described for the determination of glucose and hydrogen peroxide.
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A sensitive non-enzymatic fluorescent glucose sensor, consisting of vertically aligned ZnO nanotubes (NTs) grown on low-cost printed circuit board substrates, is described. The ZnO NTs were synthesized by a one-step hydrothermal method without using a seed layer. The sensor function is based on the photoluminescence (PL) quenching of ZnO NTs treated with different concentrations of glucose. The UV emission (emission maximum at 384 nm under 325 nm excitation) decreases linearly with increasing glucose concentration. The sensor exhibits a sensitivity of 3.5%·mM-1 (defined as percentage change of the PL peak intensity per mM) and a lower limit of detection (LOD) of 70 µM. This is better than previously reported work based on the use of ZnO nanostructures. The detection range is 0.1-15 mM which makes the sensor suitable for practical uses in glucose sensing. The sensor was successfully applied to the analysis of human blood serum samples. It is not interfered by common concentrations of ascorbic acid, uric acid, bovine serum albumin, maltose, fructose, and sucrose. Graphical abstract Schematic of the one-step, seedless hydrothermal method utilized for synthesizing vertically aligned ZnO nanotubes on printed circuit board substrates (PCBs). The ZnO nanotubes were used to monitor glucose concentrations in a non-enzymatic fluorescent sensor.
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Glicemia/análise , Corantes Fluorescentes/química , Nanotubos/química , Óxido de Zinco/química , Corantes Fluorescentes/síntese química , Calefação , Humanos , Limite de Detecção , Medições Luminescentes/métodos , Estudo de Prova de Conceito , Reprodutibilidade dos Testes , Óxido de Zinco/síntese químicaRESUMO
A sensitive nonenzymatic amperometric glucose sensor is described that relies on a glassy carbon electrode modified with a macro-/meso-porous NiCo2O4. NiCo2O4 with spinel structure has been prepared via a one-step solution combustion method. The material was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen absorption/desorption. An electrode was coated with the porous material and then displayed excellent electrocatalytic activity towards the direct oxidation of glucose in 0.15 M NaOH solution by cyclic voltammetry. Amperometric I-t curve demonstrated a sensitivity of 2100 µA·mM-1·cm-2 at an applied potential of 0.45 V (vs Hg/HgCl). The sensor has a linear response in the 0.001 to 1.0 mΜ glucose concentration range, a fast response time (3.9 s) and a low detection limit (0.38 µΜ). Graphical abstract.