Uric Acid In Biological Samples Research Articles

Rapid aqueous preparation of carbon quantum dots and their application as nanozyme for the detection of hydrogen peroxide and uric acid

A green and rapid method was developed to synthesize a series of carbon quantum dots (Fe,N/CQDs, Fe,S/CQDs, S,N/CQDs and Fe,S,N/CQDs) through thermal decomposition using persimmon frost as a carbon source. All the synthesized CQDs have peroxidase-like activity, and the comparision of their steady-state kinetic parameters inferred that the peroxidase-like activity of Fe,S,N/CQDs is superior to those of Fe,S/CQDs and Fe,N/CQDs. Furthermore, Fe,S,N/CQDs exhibited good affinity towards 3,3′,5,5′-Tetramethylbenzidine (TMB) and H2O2 compared to natural horseradish peroxidase (HRP) and other nanozymes. In theory, uric acid (UA) can produce H2O2 with the catalysis by uricase. Fe,S,N/CQDs could catalyze the breakdown of H2O2 to produce reactive oxygen species (ROS), which can oxidize TMB (colorless) to oxTMB (blue). Based on the nanozyme-catalyzed oxidation of TMB, a simple and sensitive colorimetric sensor was developed for the quantitative analysis of H2O2 and UA. Low limit of detection (0.73 μM), wide linear range (1–80 μM) and good repeatability were obtained. The sensor was also demonstrated for the determination of UA in biological samples and satisfactory results were obtained.

One-step hydrothermal approach for synthesis of hydroxy functionalized boron nitride nanosheets for fluorescence detection of uric acid in biological samples

One-step hydrothermal approach for synthesis of hydroxy functionalized boron nitride nanosheets for fluorescence detection of uric acid in biological samples

Electrochemical sensing based on biomass-derived, hierarchical, porous carbon for simultaneous detection of dopamine and uric acid

This study reported a facile, one-step activation strategy for fabricating hierarchical, nitrogen- and sulfur-doped, porous, activated carbon (NSPAC) utilizing a NaOH/thiourea aqueous system. The morphology, amorphous nature, surface area, pore volume, and elemental composition of the NSPAC was characterized using SEM, HRTEM, EDS, XRD, Raman, BET, and XPS. The as-prepared, porous carbon exhibited a large specific surface area of 1800 m2·g−1, a well-developed pore structure, and good nitrogen- and sulfur-doping of 3.29% and 0.32% respectively. The NSPAC was employed as sensitive material for constructing electrochemical sensors to determine dopamine (DA) and uric acid (UA). The glassy carbon electrode (GCE) modified with the NSPAC (NSPAC/GCE) shows excellent electrocatalytic activity and separation performance, with 135 mV of peak-to-peak separation for DA and UA. The linear response concentration of DA and UA ranges from 0.2 to 100.0 μM and from 0.2 to 50.0 μM respectively, and both have a detection limit of 0.1 μM. The analytical parameters of the sensor are excellent, and the activated carbon prepared using the alkali urea system shows considerable promise as an effective platform for monitoring trace dopamine and uric acid in biological samples.

Designed Mini Protein 20 Mimicking Uricase Encapsulated in ZIF-8 as Nanozyme Biosensor for Uric Acid Detection.

This work presents the use of encapsulated mini protein 20 mimicking uricase (mp20)-zeolitic imidazolate framework-8 (ZIF-8) as a bioreceptor for the development of a nanozyme-based electrochemical biosensor for uric acid detection. The electrochemical performance of the biofunctionalized mp20@ZIF-8 on the reduced graphene oxide/screen-printed carbon electrode (rGO/SPCE) was investigated by optimizing operating parameters such as pH, deposition potential, and deposition time using a central composite design-response surface methodology (CCD-RSM). The quadratic regression model was developed to correlate the combination of each variable to the oxidation current density as a response. A significant effect on current response was observed under optimized conditions of pH of 7.4 at −0.35 V deposition potential and 56.56 s deposition time, with p < 0.05 for each interacted factor. The obtained coefficient of determination (R2) value of 0.9992 indicated good agreement with the experimental finding. The developed nanozyme biosensor (mp20@ZIF-8/rGO/SPCE) exhibited high selectivity in the presence of the same fold concentration of interfering species with a detection limit of 0.27 μM, over a concentration range of 1 to 34 μM. The practicality of the tailored biosensor in monitoring uric acid in human serum and urine samples was validated with high-performance liquid chromatography (HPLC) and a commercial uric acid meter. Hence, nanozyme-based is a promising platform that offers a rapid, sensitive, selective, and low-cost biosensor for the non-enzymatic detection of uric acid in biological samples.

Quantitative determination of uric acid using paper-based biosensor modified with graphene oxide and 5-amino-1,3,4-thiadiazole-2-thiol.

Uric acid is the primary end product of human purine metabolism and has been regarded as a key parameter in urine and blood for monitoring physiological conditions. This paper presents a paper-based biosensor for a quantitative determination of uric acid using electrochemical detection. The working electrode of the biosensor is modified with graphene oxide (GO) and 5-amino-1,3,4-thiadiazole-2-thiol (ATT) by electropolymerizing ATT on the surface of graphene oxide. In this study, cyclic voltammetry (CV) measurements required only 200 μL of analyte solution. The experimental results showed that the oxidation peak current increased as the concentration of uric acid become higher and exhibited a linear relationship in the concentration range of 0.1-10 mM, indicating that this proposed biosensor has high sensitivity. In addition, this biosensor has good selectivity to detect uric acid because ATT has a specific binding with it. In human blood and body fluids, nitrites may be the only factor that can interfere with the detection of uric acid using this proposed biosensor. Nevertheless, uric acid can be discriminated from nitrite in the CV measurement due to different oxidation potentials. Thus, this proposed paper-based biosensor is a promising tool for detecting uric acid in biological samples.

A novel metal organic gel with superior oxidase-like activity for efficient and sensitive chemiluminescence detection of uric acid

It is found that MIL-100(Fe) gels, as a kind of metal-organic gels (MOGs), constitutting of iron (Fe3+) and trimesic acid (H3BTC), has been regarded as the efficient catalyst of luminol chemiluminescence (CL) system without the presence of extra oxidants in the present work. MIL-100(Fe) gels that have possessed mimicking oxidase-like activity can excellently enhanced luminol CL intensity by accelerating the generation of reactive oxygen species. Furthermore, with the addition of uric acid (UA), the CL signal has been dramatically inhibited under alkaline condition. Hence, the CL intensity inhibiting ratio (I0/IS) was proportional to the increasing concentration of UA in the rang from 10 nM to 4000 nM with the detection limit of 5.9 nM. This method has been successfully applied for analysis of UA with acceptable recoveries ranging from 97.0% to 107.9% in urine sample. These results indicates that this study open up a novel, sensitive and convenient method to detect UA in biological samples.

Development and validation of an economical uric acid-Fe3+/Fe2+-ferrozine-based colorimetric assay to estimate uric acid level of pure and biological samples.

This work presents the development and validation of a simple, rapid, and cost-effective spectrophotometric method for quantitative analysis of uric acid in biological samples. The method relies upon uric acid-led reduction of Fe(III) to Fe(II) of sample/standard solutions which stoichiometrically engages ferrozine to form a magenta-colored complex. Different parameters including pH, metal and chelator concentrations, temperature, etc., were optimized for the maximum intensity and stability of the complex. The uric acid concentrations of synthetic/plasma solutions were determined by comparing the color intensity of Fe(ferrozine)3 2+ complex produced by test solution with the standard curve formed by known uric acid concentrations. The method was validated in accordance with ICH guidelines and subjected to human plasma analysis. The results obtained were compared with a reference (enzymatic) method which revealed that there was no significant difference between the two methods at 95% confidence level. The method is highly specific, precise, linear, accurate, and robust.

Preparation of A Magnetic Nanosensor Based on Cobalt Ferrite Nanoparticles for The Electrochemical Determination of Methyldopa in The Presence of Uric Acid.

Methyldopa is one of the medications that is used for the treatment of hypertension. Therefore, the determination of methyldopa in the presence of other biological components is essential. In this work, a promising electrochemical sensor based on CoFe2O4 magnetic nanoparticles modified glassy carbon electrode (CoFe2O4/GCE) was developed for electrochemical determination of methyldopa in the presence of uric acid. Cobalt ferrite nanoparticles were synthesized via chemical method. Characterizing the CoFe2O4 was investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), and cyclic voltammetry techniques. Under the optimal experimental conditions, the current response of the electrochemical sensor obtained with differential pulse voltammetry was increased linearly in the concentration range from 1.45 to 15.1 μmol L-1 with the detection limit of 1.07 μmol L-1 for methyldopa. Also, by using the proposed method, methyldopa and uric acid could be analyzed in a mixture independently. The difference in peak potential for analytes is about 150 mV. The present sensor was successfully applied for the determination of methyldopa in the presence of uric acid in biological samples and the pharmaceutical samples with satisfactory results.

Trivalent Chromium Based Conversion Coating Contains Zinc/Zn(OH)2 on Iron Substrates for the Detection of Uric Acid in Biological Samples and Control of Dyeing

Trivalent Chromium Based Conversion Coating Contains Zinc/Zn(OH)2 on Iron Substrates for the Detection of Uric Acid in Biological Samples and Control of Dyeing

Engineering of Bifunctional Enzymes with Uricase and Peroxidase Activities for Simple and Rapid Quantification of Uric Acid in Biological Samples

Serum uric acid (SUA) is an important biomarker for prognosis and management of gout and other diseases. The development of a low-cost, simple, rapid and reliable assay for SUA detection is of great importance. In the present study, to save the cost of enzyme production and to shorten the reaction time for uric acid quantification, bifunctional proteins with uricase and peroxidase activities were engineered. In-frame fusion of Candida utilis uricase (CUOX) and Vitreoscilla hemoglobin (VHb) resulted in two versions of the bifunctional protein, CUOX-VHb (CV) and VHb-CUOX (VC). To our knowledge, this is the first report to describe the production of proteins with uricase and peroxidase activities. Based on the measurement of the initial rates of the coupled reaction (between uricase and peroxidase), CV was proven to be the most efficient enzyme followed by VC and native enzymes (CUOX+VHb), respectively. CV was further applied for the development of an assay for colorimetric detection of SUA, which was based on VHb-catalyzed oxidation of Amplex Red in the presence of hydrogen peroxide (H2O2). Under the optimized conditions, the assay exhibited a linear relationship between the absorbance and UA concentration over the range of 2.5 to 50 μM, with a detection limit of 1 μM. In addition, the assay can be performed at a single pH (8.0) so adjustment of the pH for peroxidase activity was not required. This advantage helped to further reduce costs and time. The developed assay was also successfully applied to detect UA in pooled human serum with the recoveries over 94.8%. These results suggest that the proposed assay holds great potential for clinical application.

Trivalent Chromium Based Conversion Coating Contains Zinc/Zn(OH)2 on Iron Substrates for the Detection of Uric Acid in Biological Samples and Control of Dyeing

Trivalent Chromium Based Conversion Coating Contains Zinc/Zn(OH)2 on Iron Substrates for the Detection of Uric Acid in Biological Samples and Control of Dyeing

Novel sonochemical synthesis of Fe3O4 nanospheres decorated on highly active reduced graphene oxide nanosheets for sensitive detection of uric acid in biological samples.

In this study, a super-active Iron (II, III) oxide nanospheres (Fe3O4 NPs) decorated reduced graphene oxide (rGOS) nanocomposite was developed. Fe3O4 NPs were stabilized on rGOS through electrostatic interactions in the aqueous medium. This process involves an ultrasound assisted reduction reaction of the GOS. The as-synthesized Fe3O4 NPs@rGOS was characterized through the HRTEM, SEM, XRD, Raman, elemental mapping and EDX analysis. The Fe3O4 NPs@rGOS modified GCE was developed for the determination of biomarker. Uric acid is important biomarker based on gout and kidney stone with high adverse effect in human body. The results obtained showed that the modified electrode Fe3O4 NPs@rGOS shows good electrochemical reduction peak compared to bare electrode and control electrodes. The Fe3O4 NPs@rGOS modified sensor linear range 0.02-783.6 µM was observed with nanomolar LOD 0.12 nM. In addition, the modified Fe3O4 NPs@rGOS/GCE sensor has been applied to determination of uric acid concentration in urine and blood serum samples. Furthermore, advantages of the modified sensor are high stability, repeatability and reproducibility.

Nanohexagonal Fe2O3 Electrode for One-Step Selective Monitoring of Dopamine and Uric Acid in Biological Samples

Fabrication of nonenzymatic biosensors based on the nanomaterials for highly sensitive and selective detection of single or multiple molecules coexisting in one biological sample is extremely challenging. Design of the hierarchical nanohexagonal Fe2O3 platelets (HFP) via one-pot hydrothermal treatment was employed for selective signaling of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA) with high sensitivity. Electrode design with the nanosized structure of parallel hexagonal platelets (20–40 nm), high surface area, multiactive site, smooth surface, and pore distribution inside/outside the surfaces renders excellent sensitivity and selectivity of DA and UA during the catalytic oxidation process. Simultaneous monitoring and selective signaling of DA and UA were successfully achieved by HFP with detection limits as low as 16 nM and 0.218 μM with a wide linear range from 1 to 200 μM and from 20 to 400 μM for DA and UA, respectively. HFP provides high stability and reproducibility with relative standard deviations in the range of 2.5–5.29% to monitor DA and UA. Furthermore, continuous monitoring of DA and UA in real human saliva/serum samples was realized with high sensitivity and selectivity. The designed HFP can be employed as a nonenzymatic biosensor for simultaneous detection of mono-bioactive molecules in the biological samples.

Determination of uric acid in biological samples by high performance liquid chromatography-electrospray ionization-tandem mass spectrometry and study on pathogenesis of pulmonary arterial hypertension in pulmonary artery endothelium cells.

Pulmonary arterial hypertension (PAH) is a severe cardiovascular disease that can lead to vascular remodelling and hypertension. Clinical diagnosis of PAH is very difficult. Uric acid (UA) can act as a biological marker for screening of PAH in patients. Multiple studies have indicated that reactive oxygen species (ROS) play an important role in the development of PAH. Thus, it is important to study the relationship between UA and ROS based on the pathogenesis of PAH. For monitoring PAH, a high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method was developed to measure the concentration of UA from rat models and pulmonary arterial endothelial cells (PAECs) models, which were induced by monocrotaline (MCT) and hypoxia, respectively. In addition, the treatment groups were treated by N-acetyl-l-cysteine (NAC), a ROS scavenger. With the confirmation from hematoxylin-eosin (H&E) staining, the HPLC-ESI-MS/MS method was adopted to successfully analyze the concentration of UA. In this study, for the first time, thymine was used as an internal standard (I.S.) of uric acid. The results showed that the UA concentration in the PAH groups was higher than that in the normal groups, while the UA concentration in the treatment groups decreased compared to that in the PAH group (p < 0.05). It was experimentally proven that the HPLC-ESI-MS/MS method is a rapid, efficient and reliable quantitative method to detect PAH. Furthermore, our results indicated that UA and ROS have a double-regulator role.

Fluorescent detection of uric acid in biological samples through the inhibition of cobalt(II) catalyzed Amplex UltraRed

A novel fluorescent probe consisting of cobalt(II)/hydrogen peroxide–Amplex® UltraRed (Co2+/H2O2–AUR) for determining uric acid (UA) concentration is reported. In the presence of H2O2, Co2+ ions underwent oxidation to produce Co3+ ions and hydroxyl radicals, which then reacted with the fluorescence reagent, AUR, forming a fluorescence product at a pH of 9.0. If UA was present, it underwent oxidation to form urea, parabanic acid, and allantoin. This inhibited the Co2+ ions-catalyzed oxidation of AUR and resulted in a substantial decreasing in fluorescence intensity that was dependent on UA concentration. The buffer systems, pH values, and the concentrations of Co2+ ions, AUR, and H2O2 were crucial parameters in determining the sensitivity and selectivity of the method for sensing UA. Under optimal conditions, the fluorescence intensity decreased linearly with UA concentration in the 0.05–1.0μmolL−1 range (R2=0.94) with a detection limit of 20nmolL−1 at a signal-to-noise ratio of 3. The analytical recoveries in urine and human serum samples were 90%–100.7% and 90%–95% respectively. This method is simpler and more cost effective than are other optical methods for the detection of UA in biological samples.

SIMULTANEOUS ELECTROCHEMICAL DETECTION OF DOPAMINE, ASCORBIC ACID AND URIC ACID USING COPPER-PHTHALOCYANINE FUNCTIONALIZED MWCNTS

ABSTRACT Multiwalled carbon nanotububes functionalized with amino groups (MWCNT-NH 2) and further modified with copper-phthalocyaninetetrasulphonate (4β(SO 3 )CuPc) were used for preparing a hybrid electrode [MWCNT-NH 2 /4β(SO 3 )CuPc/GC] using glassy carbon (GC) as a support. This hybrid electrode was tested for the detection of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA) in a PBS buffer solution at pH 6.8. The presence of the macrocyclic increased the resolution of the oxidation signals of AA, DA and UA into three very well distinct oxidation peaks. This effect was enhanced when the complex is adsorbed on multiwalled carbon nanotubes. In addition, the hybrid films provide a simple method for selective detection of DA, AA and UA in biological samples. The calibration curves for DA were obtained over the range of 1x10 -6 –1x10 -3 M, obtaining a good selectivity and sensitivity Keywords: Dopamine, ascorbic acid, uric acid, carbon nanotubes, copper-tetrasulphonate phthalocyanine, hybrids electrodes, sensor, modified electrodes.

Chemometric Strategies to Develop a Nanocomposite Electrode for Simultaneous Determination of Ascorbic Acid, Dopamine, and Uric Acid

AbstractA simple and sensitive method for simultaneously measuring dopamine (DA), ascorbic acid (AA), and uric acid (UA) using a poly(1‐aminoanthracene) and carbon nanotubes nanocomposite electrode is presented. The experimental parameters for composite film synthesis as well as the variables related to simultaneous determination of DA, AA, and UA were optimized at the same time using fractional factorial and Doehlert designs. The use of carbon nanotubes and poly(1‐aminoanthracene) in association with a cathodic pretreatment led to three well‐defined oxidation peaks at potentials around −0.039, 0.180 and 0.351 V (vs. Ag/AgCl) for AA, DA, and UA, respectively. Using differential pulse voltammetry, calibration curves for AA, DA, and UA were obtained over the range of 0.16–3.12×10−3 mol L−1, 3.54–136×10−6 mol L−1, and 0.76–2.92×10−3 mol L−1, with detection limits of 3.95×10−5 mol L−1, 2.90×10−7 mol L−1, and 4.22×10−5 mol L−1, respectively. The proposed method was successfully applied to determine DA, AA, and UA in biological samples with good results.

Simultaneous determination of dopamine and uric acid in biological samples on the pretreated pencil graphite electrode

An electrochemically pretreated pencil graphite electrode (PGE) has been proposed for simultaneous determination of dopamine (DA) and uric acid (UA) in the presence of high levels of ascorbic acid (AA). The electrochemical pretreatment of PGE was achieved in phosphate buffer (pH 7) by the potential recycling between 1.5–2.0V/SCE for 100 cycles, and at the scan rate of 100mVs−1. The influence of electrochemical pretreatment of PGE on the separation of overlapped peaks of AA, DA and UA were studied and optimum conditions were suggested. Differential pulse voltammetry (DPV) was used for simultaneous determination of DA and UA in the presence of high concentrations of AA. The peak separation between DA and AA, and also between DA and UA was up to 260 and 160mV, respectively. The calibration curves were in the range of 0.15–15μM and 0.3–150μM for DA and UA in the presence of AA, respectively. The detection limits (S/N=3) were 0.033 and 0.12μM for DA and UA, respectively. The results reveal that pretreatment of the pencil graphite electrode surface not only improves its electrochemical catalytic activities towards the oxidation of DA and UA, but also resolves the overlapped oxidation peaks of AA, DA and UA into three well-defined peaks. The present method can apply for UA and DA determination in human serum and urine, and also for some commercial pharmaceutical samples without additional sample pre-treatment.

Simultaneous determination of ascorbic acid, dopamine and uric acid using high-performance screen-printed graphene electrode

A disposable and sensitive screen-printed electrode using an ink containing graphene was developed. This electrode combined the advantages of graphene and the disposable characteristic of electrode, which possessed wide potential window, low background current and fast electron transfer kinetics. Compared with the electrodes made from other inks, screen-printed graphene electrode (SPGNE) showed excellent electrocatalytic activity for the oxidation of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Three well-defined sharp and fully resolved anodic peaks were found at the developed electrode. Differential pulse voltammetry was used to simultaneous determination of AA, DA, and UA in their ternary mixture. In the co-existence system of these three species, the linear response ranges for the determination of AA, DA, and UA were 4.0–4500μM, 0.5–2000μM, and 0.8–2500μM, respectively. The detection limits (S/N=3) were found to be 0.95μM, 0.12μM, and 0.20μM for the determination of AA, DA, and UA, respectively. Furthermore, the SPGNE displayed high reproducibility and stability for these species determination. The feasibility of the developed electrode for real sample analysis was investigated. Results showed that the SPGNE could be used as a sensitive and selective sensor for simultaneous determination of AA, DA, and UA in biological samples, which may provide a promising alternative in routine sensing applications.

Determination of uric acid in biological samples on the pretreated pencil graphite electrode

The electrochemical behavior of uric acid (UA) has been investigated on the pretreated pencil graphite electrode (PPGE). PPGE was prepared by potentiodynamic pretreatment of pencil lead in phosphate buffer solution (pH 7). On non-pretreated pencil graphite electrode (NPGE), ascorbic acid (AA) and uric acid (UA) both exhibit totally irreversible anodic peaks which overlap each other. While on PPGE, anodic peak of AA shifts to negative potentials with a decrease in peak current; but that of UA exhibits only an increase in peak current. This behavior on PPGE results in significant resolution of UA and AA peaks, which provides the voltammetric determination of UA in the presence of AA (ΔEp ≈ 320 mV). The electrochemical oxidation of UA on PPGE being a totally irreversible process is controlled by diffusion. The kinetic parameters such as charge transfer coefficient, α, and catalytic rate constant, kh, were determined for UA at PPGE. At optimum conditions of solution pH and pulse amplitude, differential pulse voltammetry (DPV) was used for determination of UA, which exhibits a linear calibration graph of Ipversus UA concentration in the range of 1–160 μM with a correlation coefficient of 0.997. The calculated detection limit for S/N = 3 was 1.9 × 10−7 M. Finally, PPGE was used for determination of UA in biological samples such as human serum and urine, using the standard addition procedure. The obtained results were compared with those of standard spectrophotometric method, which reveals that no significant difference exists at 95% confidence level between the results of these two procedures.