Uric Acid In Biological Fluids Research Articles

Ingenious fabrication of bamboo leaf-like ferric vanadate intertwined multi-walled carbon nanotubes nanocomposite as a sensitive sensor for determination of uric acid in fetal bovine serum.

Anovel nanocomposite material, ferric vanadate intertwined multi-walled carbon nanotubes (FeV/MWCNTs), has been designed which was drop-coated onto a glassy carbon electrode (GCE). The constructed sensor was used for the sensitive determination of uric acid (UA) in fetal bovine serum (FBS) and human serum (HS). A series of characterization and electrochemical tests showed that the ultrasound-assisted assembly of FeV with MWCNTs not only overcame the disadvantages of low conductivity and easy (unwanted) aggregation, but also avoided the decrease in effective surface area due to the severe aggregation of each individual raw material. The fabricated FeV/MWCNTs nanocomposites exhibited higher conductivity, larger effective surface area, and better electrocatalytic activity. In addition, under optimized conditions, the developed electrochemical sensor FeV/MWCNTs/GCE has a lower limit of detection (LOD, 0.05µM; Ep = 0.268Vvs. Ag/AgCl) and wider linear range (0.20-100µM), which can satisfy the criteria of trace UA detection. The results of UA determination in FBS (recovery = 95.5-103%; RSD ≤ 3.1%) and HS (recovery = 95.5-103%; RSD ≤ 4.3%) further validated the feasibility of FeV/MWCNTs-based electrochemical sensors for the determination of UA in biological fluids.

Determination of Uric Acid in Biological Fluids by Ceria Nanoparticles Doped Reduced Graphene Oxide Nanocomposite Voltammetric Sensor

High levels of uric acid (UA) in the human body usually cause diabetes, hypertension and atherosclerosis, kidney diseases, and neurological diseases. Hence, it is important to develop sensitive methods for UA determination. In this paper, nanocomposite composed of ceria nanoparticles and reduced graphene was successfully modified on the surface of glassy carbon electrode (ceria NPs-rGO/GCE) by a simple electroreduction method. The morphology, structure and property of the ceria NPs-rGO/GCE was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electrocatalytic activity of the ceria NPs-rGO/GCE for uric acid (UA) oxidation was studied in detail. The results showed that the ceria NPs-rGO/GCE exhibited excellent selectivity and high sensitivity for UA detection. In 0.05 M H2SO4 solution, a linear range of 0.02–20 μM and a low detection limit of 8.0 nM of UA were obtained on the ceria NPs-rGO/GCE. This developed method was successfully applied for the detection of UA in human serum and urine samples, and its recoveries reached 95.8%-105.0%.

S, N-doped carbon quantum dots enhanced Luminol-Mn(IV) chemiluminescence reaction for detection of uric acid in biological fluids

Herein, S, N doped carbon quantum dots (S, N- CQDs) were prepared by a simple hydrothermal method and characterized by transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FTIR) analysis. The influence of as-prepared CQDs was studied on the luminol- Mn(IV) CL reaction. The results indicated that S,N-CQDs remarkably increase the CL intensity of this reaction (about 13 fold). Furthermore, it was found that the CL intensity of S,N-CQDs–luminol-Mn(IV) system was significantly declined by uric acid. We exploited the amplified CL system to design a novel probe for the detection of uric acid. The CL intensity of S,N-CQDs–luminol-Mn(IV) reaction was proportional to the logarithm of uric acid concentration in the range of 0.05 to 1.5 µM, with a limit of detection of 17 nM. Based on these results, a sensitive and straightforward CL method was developed for the analysis of uric acid in biological fluids with satisfactory results.

Simultaneous electrochemical determination of levodopa and uric acid based on ZnS nanoparticles/3D graphene foam electrode

Levodopa and uric acid are important neurotransmitters associated with many neurological diseases. Abnormal concentrations of levodopa and uric acid in biological fluids can be used for the evaluation of such diseases. In this work, three-dimensional graphene foam (3D GF) was prepared by chemical vapor deposition. ZnS nanoparticles were in-situ grown on the surface of 3D GF (ZnS NPs/3D GF) using a simple hydrothermal method, which was used to simultaneously determinate levodopa and uric acid. The results show that a porous mesh film made up of ZnS NPs with the diameter of 200 nm is evenly covered on the surface of 3D GF. The ZnS NPs/3D GF electrode exhibits a high sensitivity of 2.34 and 2.39 μA·μM−1·cm−2 for the detection of levodopa and uric acid, respectively. Also, it shows a low limit of detection, excellent selectivity, good anti-interference ability and stability. Moreover, the electrode was successfully used in human plasma samples.

Poly(3-methylthiophene) modified gold sensor for determination of 3,4-dihydroxyphenylacetic acid, ascorbic acid and uric acid in biological fluids using voltammetric techniques

Poly(3-methylthiophene) modified gold sensor for determination of 3,4-dihydroxyphenylacetic acid, ascorbic acid and uric acid in biological fluids using voltammetric techniques

Carbon‐nanotube Modified Screen‐printed Electrode for the Simultaneous Determination of Nitrite and Uric Acid in Biological Fluids Using Batch‐injection Amperometric Detection

AbstractA portable electroanalytical system applied for rapid and simultaneous determination of uric acid (UA) and nitrite (NIT) in human biological fluids (urine, saliva and blood) is reported. The system is based on batch‐injection analysis with multiple‐pulse amperometric (BIA‐MPA) detection using screen‐printed electrodes (SPEs) modified with multi‐walled carbon nanotubes. Sample dilution in optimized electrolyte (0.1 mol L−1 Britton‐Robinson buffer pH 2) followed by injection of 100 μL on the electrode surface using an electronic micropipette is performed. UA is detected at +0.45 V and both UA+NIT at +0.70 V. Linear calibration plots for UA and NIT were obtained over the range of 1–500 μmol L−1 with detection limits of 0.05 and 0.06 μmol L−1, respectively. For comparison, a differential‐pulse voltammetric (DPV) method was optimized, and linear calibration plots for UA and NIT were obtained over range of 1–30 μmol L−1 and 1–40 μmol L−1 with detection limits of 0.1 and 0.3 μmol L−1, respectively. BIA‐MPA is highly precise (RSD<1.3 %), fast (160 h−1) and free from sample‐matrix interferences as recovery values ranged from 77 to 121 % for spiked samples (short contact time of sample aliquot with SPE). Contrarily, recovery tests conducted using DPV did not provide adequate recovery values (>150 %), probably due to the longer contact time of the SPE with the biological samples during analysis leading to a severe interference of sample matrices.

Au-IDA microelectrodes modified with Au-doped graphene oxide for the simultaneous determination of uric acid and ascorbic acid in urine samples

An electrochemical sensor based on graphene oxide decorated with gold nanoparticles has been prepared for the simultaneous quantification of uric acid (UA) and ascorbic acid (AA) in urine samples. The gold interdigitated microelectrodes array (Au-IDA) has been modified using graphene oxide doped with gold nanoparticles (AuNPs-GO/Au-IDA), which was characterized by TEM, FE-SEM, XPS and cyclic voltammetry. Excellent results were obtained for the separate quantification of UA and AA by chronoamperometry. The electrochemical sensor exhibits limits of detection (LODs) of 1.4μM and 0.62μM for AA and UA, respectively, limits of quantification (LOQs) of 4.6μM (AA) and 2.0μM (UA), and the working ranges obtained were between 4.6μM and 193μM for AA and between 2μM and 1.05mM for UA. The repeatability was studied at 20μM providing coefficients of variation of 16% for AA and 13% for UA. Moreover, UA does not interfere in the measurement of AA and viceversa (provided that the concentration of UA is equal to or higher than 450μM in the latter case). For lower concentrations of UA, an easy and fast strategy to quantify both analytes is presented. The good electrocatalytic activity achieved with this material makes it useful for the quantification of AA and UA in biological fluids. Other analytes like glucose, dopamine and epinephrine have been investigated. The results allow us to conclude that they do not interfere in the quantification of AA and UA in PBS (0.25M, pH 7.0). Human urine samples have been analyzed using the method proposed, contaning AA and UA concentration levels of (0.588±0.002) mM and (1.43±0.02) mM, respectively, which are in the concentration range of these analytes in urine samples for healthy people.

A novel electrochemical platform for sensitive and simultaneous determination of dopamine, uric acid and ascorbic acid based on Fe3O4[sbnd]SnO2[sbnd]Gr ternary nanocomposite

A ternary nanocomposite of Fe3O4SnO2Gr was synthesized and characterized by scanning electron microscopy and X-ray diffraction. A novel sensing layer was constructed by incorporation of the prepared nanocomposite into carbon paste electrode (CPE) for the simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Three clear and well-separated voltammetric peaks along with the remarkably increased electro-oxidation currents were obtained on the modified electrode (Fe3O4SnO2Gr/CPE) in differential pulse voltammetry (DPV) measurements. The linear calibration curves were obtained by plotting the peak currents against the analytes concentrations in the range of 0.1 to 23.00, 0.02 to 2.8, and 0.015 to 2.40μM, with detection limits of 62.0, 7.1 and 5.0nM for AA, DA, and UA, respectively. Additionally, the Fe3O4SnO2Gr/CPE presented a noticeable anti-interference ability, stability, and reproducibility. Also, the obtained electrode showed satisfactory results when applied for the determination of the AA, DA and UA in biological fluids and pharmaceutical samples.

Uric acid detection by means of SERS spectroscopy on dried Ag colloidal drops

Uric acid concentration in human bodily fluids is an important marker for disorders such as gout, pre‐eclamsia or cardiovascular disease. However, currently used methods for its detection either lack sensitivity or require sophisticated, bulky and expensive equipment. In this work, we show that by using surface‐enhanced Raman scattering spectroscopy (SERS) on dried Ag colloidal drops and with 1064 nm excitation, concentrations of uric acid in aqueous solutions down to 10−6 M can be detected. Such sensitivity is sufficient for medical applications as concentration of uric acid in various bodily fluids are in the range of 10−3–10−4 M. Drying of the colloidal drops is known to result in the formation of ‘coffee‐ring’ structures that allow obtaining high enhancements but poor reproducibility. Here, the formation of the structures was avoided by choosing aluminum oxide as a base substrate and by controlling environment conditions. Despite the fact that variations of signal enhancement from sample to sample prevent quantitative analysis from being performed, the results of this work imply that strict control of sample preparation conditions could lead to obtaining reproducible SERS enhancements. Results of density functional theory calculations of uric acid tautomer – five‐atom silver cluster complexes performed for the first time show that the differences between Raman and SERS spectra of uric acid can be mainly explained by tautomerization of the molecule and its bonding to the silver surface. Assignment of spectral bands is important for correct SERS signal interpretation and detection of uric acid in biological fluids in the future studies. (Less)

Highly sensitive colorimetric detection of glucose and uric acid in biological fluids using chitosan-modified paper microfluidic devices

This paper describes the modification of microfluidic paper-based analytical devices (μPADs) with chitosan to improve the analytical performance of colorimetric measurements associated with enzymatic bioassays. Chitosan is a natural biopolymer extensively used to modify biosensing surfaces due to its capability of providing a suitable microenvironment for the direct electron transfer between an enzyme and a reactive surface. This hypothesis was investigated using glucose and uric acid (UA) colorimetric assays as model systems. The best colorimetric sensitivity for glucose and UA was achieved using a chromogenic solution composed of 4-aminoantipyrine and sodium 3,5-dichloro-2-hydroxy-benzenesulfonate (4-AAP/DHBS), which provided a linear response for a concentration range between 0.1 and 1.0 mM. Glucose and UA were successfully determined in artificial serum samples with accuracies between 87 and 114%. The limits of detection (LODs) found for glucose and UA assays were 23 and 37 μM, respectively. The enhanced analytical performance of chitosan-modified μPADs allowed the colorimetric detection of glucose in tear samples from four nondiabetic patients. The achieved concentration levels ranged from 130 to 380 μM. The modified μPADs offered analytical reliability and accuracy as well as no statistical difference from the values achieved through a reference method. Based on the presented results, the proposed μPAD can be a powerful alternative tool for non-invasive glucose analysis.

A new sensor based on In doped CeO2 nanoparticles modified glassy carbon paste electrode for sensitive determination of uric acid in biological fluids

A novel In doped CeO2 nanoparticles modified glassy carbon paste electrode (nano-In–CeO2/GCPE) was prepared and applied for selective and sensitive electrochemical determination of uric acid (UA). In doped CeO2 nanoparticles were characterized by X-ray diffraction, energy-dispersed X-ray spectrometry (EDS) and transmission electron microscopy (TEM). Scanning electron microscopy (SEM) and cyclic voltammetry (CV) were employed for the surface analysis of the modified electrodes. Compared with undoped CeO2, the In (5wt.%) doped CeO2 modified electrode exhibits high effective surface area, more reactive site and excellent electrochemical catalytic activity toward the oxidation of UA. The prepared nano-In–CeO2/GCPE showed high selectivity and sensitive for UA oxidation over ascorbic and dopamine. This In–CeO2 nanoparticles modified electrode responded to UA linearly over a concentration range from 7.90×10−8 to 1.48×10−5M with a detection limit of 7.40×10−9M UA (1.24ng/mL). The fabricated sensor showed anti-interference ability against the physiological common interferents (i.e. adenine, guanine and xanthine) and provided to be useful for the determination of UA in human blood serum and urine samples with satisfactory results.

MgO nanobelt-modified graphene-tantalum wire electrode for the simultaneous determination of ascorbic acid, dopamine and uric acid

ABSTRACT A promising electrochemical biosensor for simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA) was fabricated by electrochemical deposition of MgO nanobelts on a graphene-modified tantalum wire (denoted as MgO/Gr/Ta) electrode. The MgO nanobelts and graphene were verified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrochemical performances of the electrodes were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The CV results show that AA, DA and UA could be detected simultaneously using MgO/Gr/Ta electrode with peak-to-peak separation of 300 mV, 147 mV and 447 mV for AA-DA, DA-UA and AA-UA, respectively. In the threefold co-existence system, the linear calibration plots for AA, DA and UA were obtained over the concentration range of 5.0–350 μM, 0.1–7 μM and 1–70 μM with detection limits of 0.03 μM, 0.15 μM and 0.12 μM, respectively. The modified electrode shows excellent selectivity, good sensitivity and good stability, making it attractive as a sensor for simultaneous detection of AA, DA and UA in biological fluids.

Graphene nanosheets as a sensing platform for amplified electrochemical measurement of quercetin and uric acid in biological fluids

A simple and selective electrochemical method was investigated for the simultaneous determination of quercetin (Qu) and uric acid (UA) in aqueous media (citrate buffer solution, pH 4.0) on a glassy carbon electrode modified with graphene nanosheets as a sensing platform (GNSs/GCE). Cyclic voltammetry, transmission electron microscopy, and Fourier transform infrared spectroscopy were employed to characterize the nanostructure of the sensor. Separation of the oxidation peak potentials for Qu and UA was about 160 mV, and the anodic currents for the oxidation of both Qu and UA are greatly increased at GNSs/GCE, which makes it suitable for simultaneous determination of these compounds. The detection limits were 0.0011 and 0.0137 μmol/L for Qu and UA, respectively. The method was applied to the determination of Qu and UA in human blood serum and urine samples.

Magnetic core–shell Fe3O4@SiO2/MWCNT nanocomposite modified carbon paste electrode for amplified electrochemical sensing of uric acid

A new type of nanocomposite based on multi-walled carbon nanotubes decorated with magnetic core–shell Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2/MWCNTs) was prepared and used to fabricate a modified carbon paste electrode (CPE). The nanocomposite was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR) techniques. Electrochemical behavior of uric acid (UA) was investigated on Fe3O4@SiO2/MWCNTs-CPE by cyclic voltammetry (CV) and square wave voltammetry (SWV) in phosphate buffer solution (pH6.0). Under the optimized conditions, the peak currents increased linearly with the concentration of UA in the range from 0.60 to 100.0μM, with a detection limit of 0.13μM. The proposed sensor was successfully applied for the determination of UA in biological fluids.

Chromogenic System for Measuring Hydrogen Peroxide: The Enzymatic Uric Acid Assay

Featured Article: Fossati P, Prencipe L, Berti G. Use of 3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone chromogenic system in direct enzymic assay of uric acid in serum and urine. Clin Chem 1980;26:227–31.1 Our 1980 report in Clinical Chemistry described an improved chromogenic detection system that, coupled with the enzyme oxidation of uric acid, led to a direct method for assaying uric acid in biological fluids. The system assay was reliable, simple, rapid, and suitable for either manual or automated procedures. The work was developed in the context of the Sera-Pak line of clinical chemistry reagents at Miles Italiana SpA’s Ames research and development laboratories. This line of reagents was marketed in 58 countries throughout the world. Before our investigation, chemical and enzymatic methods for uric acid assay had been described, but these assays had practical disadvantages: lack of direct assay in a small sample with a single reagent, need for a serum blank, long incubation times, and false negatives …

Conventional and planar chip sensors for potentiometric assay of uric acid in biological fluids using flow injection analysis

The potentiometric response properties of several PVC-based membrane sensors using phthalocyanine complexes of cobalt(II) (CoPC) and Fe(II) (FePC) as anion carriers, towards uric acid were constructed and characterized. The sensors demonstrated fast near-Nernstian response for uric acid over the concentration ranges 9.1 × 10 −6 to 9.1 × 10 −2 and 3.1 × 10 −5 to 3.1 × 10 −2 M with detection limits 0.67 and 2.85 μg mL −1 over pH 6.5–8 for CoPC and FePC based membrane sensors plasticized with o-NPOE and 1% TDMAC, respectively. A novel solid-state planar chip urate sensor was developed, characterized according to IUPAC recommendations, easily used in a single channel wall-jet flow injection system and compared with a tubular detector. The intrinsic characteristics of the detectors in a low dispersion manifold were determined and compared with data obtained under hydrodynamic mode of operation. Validation of the assay methods with the proposed sensors by measuring the lower limit, range, accuracy, precision, repeatability and between-day-variability revealed good performance characteristics confirming applicability for continuous determination of uric acid. The sensors were used for determining urate in biological fluids at an input rate of 50 samples per hour. The results compare favorably with data obtained by the standard spectrophotometry.

A ratiometric and non-enzymatic luminescence assay for uric acid: differential quenching of lanthanide excited states by anti-oxidants

The excited states of Tb and Eu complexes of a common macrocyclic ligand are quenched preferentially by electron transfer from the urate anion, allowing the creation of a new assay to measure uric acid in biological fluids.

An Inexpensive Biosensor for Uric Acid Determination in Human Serum by Flow-Injection Analysis

An inexpensive and easy to construct miniaturized biosensor is described for the determination of uric acid in biological fluids. The amperometric biosensor was prepared by using a carbon paste electrode prepared with uricase from Arthrobacter globiforms and tetracyanoquinodimethane as electron transfer mediator. When incorporated into a flow-injection system it was enabled to perform 50 measurements/h of uric acid in the analytical range of 1–100 μmol dm−3 with a relative standard deviation of 0.20% (n=14). The system was applied to human serum samples analysis providing good data correlation with those obtained by the reference spectrophotometric method. A linear relationship AM (μmol dm−3)=1.02 (±0.05) SP (μmol dm−3) −0.12 (±0.13) was obtained evidencing the absence of significant error. The constructed biosensor was successfully used for at least four months (250 assays) with only a 13% of decrease in the enzymatic activity.

Biological microsystem for measuring uric acid in biological fluids

This paper describes a biological microsystem (bio-system) for measuring uric acid concentration in serum, plasma or urine. Its operation is based on optical absorption in a well-defined part of the visible spectrum. The bio-system is composed by two dies: one is fabricated in polystyrene and contains the microchannels and the other is fabricated in a CMOS standard process and contains the photodetector and readout electronics. The uric acid concentration is measured by using a mixture of 14 l of infinity TM uric acid reagent with 0.25 lo f sample. The achieved sensitivity is 0.33 mg/dl (±0.6% of the value in urine of a healthy person), with a 1 mm lightpath. Using an optical absorption method, a maximum peak at wavelength λ = 494 nm, is detected. This bio-system can be included in the group of low-cost disposable devices for biological fluids analysis. © 2003 Elsevier B.V. All rights reserved.

Miniaturized graphite sensors doped with metal-bathophenanthroline complexes for the selective potentiometric determination of uric acid in biological fluids.

Miniaturized poly(vinyl chloride) matrix membrane sensors in an all-solid-state graphite support, responsive to urate anion, were developed. The membranes incorporate lipophilic ion-pair complexes of urate anion with ruthenium(III), iron(II), nickel(II) and copper(I) bathophenanthroline (4,7-diphenyl-1,10-phenanthroline) counter cations. The sensors demonstrate a near-Nernstian response to urate over the concentration range 1 x 10(-2)-1 x 10(-5) mol l-1 and have micromolar detection limits and good selectivity properties. The response is virtually unaffected by pH changes in the range 7-10 and the response times are 5-10 s in aqueous solutions and in human serum and urine samples. A flow injection detector incorporating an iron(II) bathophenanthroline-urate graphite sensor was used for continuous monitoring of uric acid. The minimum detectable concentration was approximately 8 micrograms ml-1 and the sample throughput was approximately 120 h-1. Direct potentiometric determination of uric acid in the static and hydrodynamic modes of operation over the range 15 micrograms ml-1-1.5 mg ml-1 showed average recoveries of 98.7 and 97.8% with RSDs of 0.6 and 0.7%, respectively. Application of the method to the determination of uric acid in human serum and urine gave results that compared favourably with those obtained by the standard spectrophotometric method.