Uric Acid Assay Research Articles

An amperometric biosensor and a biofuel cell of uric acid based on a chitosan/uricase–poly(furan-3-boronic acid)–Pd nanoparticles/plated Pd/multiwalled carbon nanotubes/Au electrode

A chitosan (CS)/uricase (UOx)–poly(furan-3-boronic acid) (PFBA)–Pd nanoparticles (PdNPs)/plated Pd (Pdplate)/multiwalled carbon nanotubes (MWCNTs)/Au electrode was prepared for fabricating an amperometric biosensor and a biofuel cell (BFC) of uric acid (UA). Briefly, Pd was electroplated on a MWCNTs-modified Au electrode, the UOx–PFBA–PdNPs bionanocomposite was prepared on the Pdplate/MWCNTs/Au electrode through chemical oxidation of a UOx-furan-3-boronic acid adduct by Na2PdCl4, and then chitosan (CS) was cast-coated on the electrode. In the first-generation biosensing mode (anodic detection of enzymatically generated H2O2), the prepared CS/UOx–PFBA–PdNPs/Pdplate/MWCNTs/Au electrode showed a linear amperometric response to UA concentration from 1.0μM to 2.5mM with a sensitivity of 490μAmM−1cm−2 and a limit of detection (S/N=3) of 0.1μM, excellent operation/storage stability, and good results of UA assay in real urine samples. The enzyme electrode also worked well in the second-generation biosensing mode involving a p-benzoquinone or ferrocene monocarboxylic acid mediator. Furthermore, a monopolar UA BFC was fabricated by using the enzyme electrode as the bioanode and a Pt/MWCNTs/Au electrode as the cathode, which gave an open-circuit cell voltage of 0.394V, a short-circuit current density of 857μAcm−2 and a maximum power density of 70μWcm−2 at 0.22V under simulated physiological conditions.

Cotton-based diagnostic devices.

A good diagnostic procedure avoids wasting medical resources, is easy to use, resists contamination, and provides accurate information quickly to allow for rapid follow-up therapies. We developed a novel diagnostic procedure using a “cotton-based diagnostic device” capable of real-time detection, i.e., in vitro diagnostics (IVD), which avoids reagent contamination problems common to existing biomedical devices and achieves the abovementioned goals of economy, efficiency, ease of use, and speed. Our research reinforces the advantages of an easy-to-use, highly accurate diagnostic device created from an inexpensive and readily available U.S. FDA-approved material (i.e., cotton as flow channel and chromatography paper as reaction zone) that adopts a standard calibration curve method in a buffer system (i.e., nitrite, BSA, urobilinogen and uric acid assays) to accurately obtain semi-quantitative information and limit the cross-contamination common to multiple-use tools. Our system, which specifically targets urinalysis diagnostics and employs a multiple biomarker approach, requires no electricity, no professional training, and is exceptionally portable for use in remote or home settings. This could be particularly useful in less industrialized areas.

Molecularly imprinted titania nanoparticles for selective recognition and assay of uric acid

Molecularly imprinted titania nanoparticles are su ccessfully synthesized by sol–gel method for the selective recognition of uric acid. Atomic force microscopy is used to study the morphology of uric acid imprinted titania nanoparticles with diameter in the range of 100–150 nm. Scanning electron microscopy images of thick titania layer indicate the formation of fine network of titania nanoparticles with uniform distribution. Molecular imprinting of uric acid as well as its subsequent washing is confirmed by Fourier transformation infrared spectroscopy measurements. Uric acid rebinding studies reveal the recognition capability of imprinted particles in the range of 0.01–0.095 mmol, which is applicable in monitoring normal to elevated levels of uric acid in human blood. The optical shift (signal) of imprinted particles is six times higher in comparison with non-imprinted particles for the same concentration of uric acid. Imprinted titania particles have shown substantially reduced binding affinity toward interfering and structurally related substances, e.g. ascorbic acid and guanine. These results suggest the possible application of titania nanoparticles in uric acid recognition and quantification in blood serum.

Plant flavone apigenin protects against cyclosporine-induced histological and biochemical changes in the kidney in rats

Cyclosporine (CsA) is an immunosuppressant drug universally used for the prevention of transplant rejection and also for the treatment of autoimmune diseases. Use of cyclosporine has been limited by its side effects such as hypertension and renal damage. Antioxidants are known to protect free radical induced damage of tissues during drug toxicity. The aim of this study was to test the role of plant flavone apigenin against cyclosporine-induced nephrotoxicity. Adult male Sprague Dawley rats were randomly divided into control, cyclosporine alone, and cyclosporine with apigenin (10, 15 and 20mg/kg). Cyclosporine treatment was continued for 21days to induce nephrotoxicity. From the blood samples, urea, uric acid, total antioxidants and lipid hydroperoxide assays were done. There was a significant renal damage with cyclosporine alone treatment. Blood urea nitrogen, urea, uric acid and lipid hydroperoxides were significantly elevated whereas there was a significant decrease in the total antioxidant levels. Treatment with apigenin significantly reduced the lipid hydroperoxides and increased the total antioxidant levels. Concurrent apigenin treatment significantly reduced the histopathological changes in the CsA treated groups. In conclusion, the study confirmed the role of oxidative stress in the pathogenesis of cyclosporine-induced nephrotoxicity and protective effects of flavone apigenin against free radical-induced renal damage.

THU0547 Association of Asymptomatic Hyperuricemia and Endothelial Dysfunction in Psoriatic Arthritis

BackgroundCardiovascular disease is an increasingly recognized contributor to excess morbidity and mortality in psoriatic arthritis (PsA). Atherosclerosis is a multifocal, immune-inflammatory disease affecting the medium and large arteries. There is...

Optimization of pH values to formulate the bireagent kit for serum uric acid assay

A new formulation of the bireagent kit for serum uric acid assay was developed based on the effects of pH on enzyme stability. At 4°C, half-lives of uricases from Bacillus fastidious and Arthrobacter globiforms were longer than 15 months at pH 9.2, but became shorter at pH below 8.0; half-lives of ascorbate oxidase and peroxidase were comparable at pH 6.5 and 7.0, but became much shorter at pH higher than 7.4. In the new formulation of the bireagent kit, Reagent A contained peroxidase, 4-aminoantipyrine, and ascorbate oxidase in 50mM phosphate buffer at pH 6.5; Reagent B contained B. fastidious or A. globiforms uricase in 50mM sodium borate buffer at pH 9.2; Reagents A and B were mixed at 4:1 to produce a final pH from 7.2 to 7.6 for developing a stable color. The new bireagent kit consumed smaller quantities of three enzymes for the same shelf life. With the new bireagent kit, there were linear responses of absorbance at 546nm to uric acid up to 34mM in reaction mixtures and a good correlation of uric acid levels in clinical sera with those by a commercial kit, but stronger resistance to ascorbate. Therefore, the new formulation was advantageous.

Oxidation of C60 Aerosols by Atmospherically Relevant Levels of O3

Atmospheric processing of carbonaceous nanoparticles (CNPs) may play an important role in determining their fate and environmental impacts. This work investigates the reaction between aerosolized C60 and atmospherically relevant mixing ratios of O3 at differing levels of humidity. Results indicate that C60 is oxidized by O3 and forms a variety of oxygen-containing functional groups on the aerosol surface, including C60O, C60O2, and C60O3. The pseudo-first-order reaction rate between C60 and O3 ranges from 9 × 10(-6) to 2 × 10(-5) s(-1). The reaction is likely to be limited to the aerosol surface. Exposure to O3 increases the oxidative stress exerted by the C60 aerosols as measured by the dichlorofluorescein acellular assay but not by the uric acid, ascorbic acid, glutathione, or dithiothreitol assays. The initial prevalence of C60O and C60O2 as intermediate products is enhanced at higher humidity, as is the surface oxygen content of the aerosols. These results show that C60 can be oxidized when exposed to O3 under ambient conditions, such as those found in environmental, laboratory, and industrial settings.

Assessment of the Trueness and Inter-Laboratory Precision of Routine Uric Acid Assays Using 4 Frozen Pooled Serum Samples Measured by the Japan Society of Clinical Chemistry's HPLC Method

BackgroundReference procedures are required for evaluating the accuracy of routine analytical systems for uric acid (UA). External quality assessment (EQA) for UA has only been conducted with quality controls in China, and the results have not been published. This study was designed to investigate both the trueness and inter-laboratory precision of UA measurements among routine analytical systems using a candidate reference method.MethodsWe performed the HPLC method recommended by the Japan Society of Clinical Chemistry (JSCC). Next, we evaluated its analytical performance and validated its trueness. The performance of 4 routine analytical systems (5 instruments per system, n=20) for UA was assessed by using 4 frozen pooled serum samples measured by the HPLC method according to biologically relevant quality goals.ResultsWithin-run, between-run, inter-day, and total CV of the method were less than 0.3%, 0.4%, 1.8%, and 2.6%, respectively. The UA measurements were consistent with the target values of standard reference material (SRM) 909b, the sixth ring trial for Reference Laboratories (RELA-2008) specimen, and national primary reference materials. The 4 frozen pooled serum samples were homogeneous, stable, and commutable. All routine systems achieved the desirable performance goal (total error <11.9%).ConclusionsWe successfully reproduced the JSCC's HPLC method, which was simple, specific, precise, and accurate. We recommend this method as a reference method for UA measurement in human serum. Four routine analytical systems for UA measurement had acceptable traceability, and their UA results showed good concordance.

Ethamsylate (Dicynone) interference in determination of serum creatinine, uric acid, triglycerides, and cholesterol in assays involving the Trinder reaction; in vivo and in vitro.

The aim of our research was the quantification of interfering properties of the haemostatic drug Dicynone (ethamsylate) in serum creatinine, uric acid, cholesterol, and triglyceride assays using the Trinder reaction. Blood from patients was collected before and 15 minutes after administration of 500 mg Dicynone dose i.v. and the above mentioned analytes were quantified using Roche assays (Cobas 8000). In our in vitro experiment, we measured concentrations of the analytes in pooled serum aliquots with final concentrations of Dicynone additions 0, 30, 60, 150, and 300 mg/L. Aliquots with 60 mg/L Dicynone were also measured at 2, 6, and 8 hours after initial measurement when stored in 22 degrees C and 4 degrees C for comparison. Concentrations of the measured analytes in samples from patients administered with a 500 mg dose of Dicynone were lower in all cases (n = 10) when compared to values in samples taken immediately before treatment. The in vitro samples showed that considerable negative interference occurred even with the low concentrations of Dicynone additions (30 and 60 mg/L), showing the strongest negative interference in creatinine values, followed by uric acid, triglycerides, and cholesterol. Using in vitro samples, we showed strong time and temperature dependence on Dicynone interference. We found and proved significant negative interference of the drug Dicynone (ethamsylate) in the clinical analysis of blood using in vivo and in vitro experiments. Furthermore, we observed a change of this effect in serum matrix over time and at different storage temperatures.

Prevalence of preclinical renal dysfunction in obese Egyptian patients with primary knee osteoarthritis, preliminary data

Aim of the workObesity and the related metabolic syndrome cluster of cardiovascular risk factors have been associated with chronic kidney disease (CKD). Patients with knee osteoarthritis (OA) are frequently obese and due to the combined effects of obesity and the chronic use of non-steroidal anti-inflammatory drugs (NSAIDs); they may represent a high risk group for renal dysfunction. We aimed to detect preclinical renal involvement in obese patients with knee OA. Patients and methodsForty patients with knee OA and a body mass index (BMI)⩾30 (mean age 43.5±3.7years) not on chronic NSAID use and forty age and sex matched non-obese controls were enrolled in this study. For all subjects anthropometric measures were taken. Laboratory assessment included fasting blood sugar, serum triglycerides, high density lipoprotein cholesterol (HDL), serum uric acid, urea, creatinine and microalbuminuria assay. For patients with knee OA, knee radiographs were done and the disease severity was assessed according to Kellgren–Lawrence (K–L) scale. Tc-99m DTPA was used for the measurement of the glomerular filtration rate (GFR) and the results were classified into normal and CKD according to Kidney–Dialysis Outcomes and Quality Initiative stages. ResultsAmong the patients’ group, 26/40 (65%) had CKD compared to 12/40 (30%) subjects among the controls (P=0.001). GFR correlated positively with HDL (r=0.4; P=0.02) and inversely with microalbuminuria and the severity of knee OA (r=−0.4; P=0.02 for each). ConclusionsObese patients with knee OA represent a high risk group for renal dysfunction.

Selective and sensitive determination of uric acid in the presence of ascorbic acid and dopamine by PDDA functionalized graphene/graphite composite electrode

In this work, a facile electrochemical sensor based on poly(diallyldimethylammonium chloride) (PDDA) functionalized graphene (PDDA-G) and graphite was fabricated. The composite electrode exhibited excellent selectivity and sensitivity towards uric acid (UA), owing to the electrocatalytic effect of graphene nanosheets and the electrostatic attractions between PDDA-G and UA. The anodic peak current of UA obtained by cyclic voltammetry (CV) increased over 10-fold compared with bare carbon paste electrode (CPE). And the reversibility of the oxidation process was improved significantly. Differential pulse voltammetry (DPV) was used to determine UA in the presence of ascorbic acid (AA) and dopamine (DA). It was found that all of oxidation peaks of three species could be well resolved, and the peak current of UA was much stronger than the other two components. More importantly, considerable-amount of AA and DA showed negligible interference to UA assay. The calibration curve for UA ranged from 0.5 to 20μmolL−1 with a correlation coefficient of 0.9934. The constructed sensor has been employed to quantitatively determine UA in urine samples.

Redox-active thionine–graphene oxide hybrid nanosheet: One-pot, rapid synthesis, and application as a sensing platform for uric acid

In this paper, we fabricate a sensitive and stable amperometric UA amperometric biosensor using nanobiocomposite derived from thionine modified graphene oxide in this study. A simple wet-chemical strategy for synthesis of thionine–graphene oxide hybrid nanosheets (T–GOs) through π–π stacking has been demonstrated. Various techniques, such as UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemistry have been utilized to characterize the formation of the T–GOs. Due to the synergistic effect between thionine and graphene oxide, the nanosheets exhibited excellent performance toward H2O2 reduction. The incorporation of thionine onto graphene oxide surface resulted in more than a twice increase in the amperometric response to H2O2 of the thionine modified electrode. The as-formed T–GOs also served as a biocompatible matrix for enzyme assembly and a mediator to facilitate the electron transfer between the enzyme and the electrode. Using UOx as a model system, we have developed a simple and effective sensing platform for assay of uric acid at physiological levels. UA has been successfully detected at −0.1V without any interference due to other electroactive compounds at physiological levels of glucose (5mM), ascorbic acid (0.1mM), noradrenalin (0.1mM), and dopamine (0.1mM). The response displays a good linear range from 0.02 to 4.5mM with detection limit 7μM. The application of this modified electrode in blood and urine UA exhibited a good performance. The robust and advanced hybrid materials might hold great promise in biosensing, energy conversion, and biomedical and electronic systems.

Association of asymptomatic hyperuricemia and endothelial dysfunction in psoriatic arthritis

IntroductionCardiovascular disease is an increasingly recognized contributor to excess morbidity and mortality in psoriatic arthritis (PsA). Traditional cardiovascular risk factors do not adequately account for the extent of cardiovascular disease in PsA. Aim of the workTo examine the prevalence of subclinical atherosclerosis in patients with PsA to emphasize the potential role of serum uric acid on endothelial dysfunction, as an early predictor for atherosclerosis in PsA patients. Patients and methodsThis study included 60 PsA patients as well as 60 age and sex matched healthy controls. Assay of serum uric acid, interleukin-6 (IL-6) and soluble intercellular adhesion molecule-1 (sICAM-1) was done for all patients and controls. Patients were subjected to psoriasis area severity index (PASI) and assessment of disease activity. Patients and controls underwent brachial flow-mediated dilatation (FMD) assessment by color duplex sonography to determine endothelial dysfunction as well as extracranial carotid arteries assessment by high-resolution B-mode ultrasound to measure the common carotid intima-media thickness (CIMT) and the detection of atheromatous plaques. ResultsPsA patients have a high significant difference in CIMT, FMD of the brachial artery and mean levels of serum uric acid compared to healthy controls (p<0.001). PsA patients with hyperuricemia have a high significant difference in CIMT and FMD of the brachial artery than those with normal serum uric acid. Serum uric acid levels showed a high significant positive correlation with each of CIMT, disease duration, markers of inflammation (ESR, CRP, IL-6, sICAM-1), disease activity score in 28 joints (DAS 28) and PASI (r=0.71, 0.893, 0.956, 0.858, 0.853, 0.877, 0.907, 0.847, respectively, as p<0.001). A high significant negative correlation was found between serum uric acid levels and FMD of the brachial artery as r=−0.634, p<0.001. ConclusionPatients with PsA have a high prevalence of subclinical atherosclerosis dependent on serum uric acid, suggesting that chronic systemic inflammation and endothelial dysfunction appear to be the link between asymptomatic hyperuricemia and atherosclerosis. Therefore, proper control of serum uric acid may play a preventive role in the development of atherosclerosis in PsA patients.

Gold nanoparticle–enzyme conjugates based FRET for highly sensitive determination of hydrogen peroxide, glucose and uric acid using tyramide reaction

In this paper, we report a new strategy for highly sensitive determination of hydrogen peroxide, glucose and uric acid based on fluorescence resonance energy transfer (FRET) using gold nanoparticles (AuNPs) as energy acceptors. The principle is based on highly sensitive reaction of tetramethyl rhodamine (TMR) labeled tyramide and hydrogen peroxide catalysed by horseradish peroxidase (HRP), and the fluorescence spectrum of TMR (EX(max) 575 nm) partially overlaps with the visible absorption bands of AuNPs. We demonstrated an efficient FRET between tyramide labeled TMR (as energy donors) and HRP (BSA) conjugated AuNPs (as energy acceptors) due to the formation of TMR-labeled HRP-AuNPs or TMR-labeled BSA-AuNPs in the presence of H(2)O(2). We observed that the quenching of the fluorescence signal depended linearly on the H(2)O(2) concentration within a range of concentrations from 25 to 400 nM and the detection limit of this assay was 10 nM. Based on the principle for determination of H(2)O(2), we developed a new strategy for assay of glucose and uric acid by coupling with glucose oxidase (GOx)-mediated and uricase-mediated reaction. The established methods were successfully used for determination of glucose and uric acid levels in human sera, and the results obtained are in good agreement with commercially available methods. Our methods are at least 1 order of magnitude more sensitive than the commercially available methods. More importantly, our method described here can be extended to other assay designs using different oxidase enzymes, energy donors and energy acceptors, such as fluorescent quantum dots, near-infrared (NIR)-to-visible upconversion nanoparticles and even other metallic nanoparticles.

Hyperuricemia is associated with histological liver damage in patients with non-alcoholic fatty liver disease

Hyperuricemia has been associated with metabolic disorders. In this line recent studies observed an independent link between higher uric acid serum levels and clinical diagnosis of non-alcoholic fatty liver disease (NAFLD). We aimed to assess the potential association between uric acid serum levels and histological liver damage in a homogeneous cohort of biopsy-proven NAFLD patients. Consecutive NAFLD patients (n = 166), assessed by liver biopsy (Kleiner score), anthropometric, biochemical and metabolic features, were included. Enzymatic colorimetric test was used for serum uric acid assays (Roche Diagnostics GmbH, Mannheim, Germany). Hyperuricemia was diagnosed when uric acid serum levels were > 7 mg/dL in men, and > 6 mg/dL in women. Mean uric acid serum level was 5.75 mg/dL, and about 20% of patients had hyperuricemia, that was independently associated with younger age (OR 0.951, 95% CI 0.918-0.984, P = 0.004), lobular inflammation (OR 2.144, 95% CI 1.055-4.357, P = 0.03) and steatosis grade (OR 1.859, 95% CI 1.078-3.205, P = 0.02), by multivariate logistic regression analysis. Female gender (OR 2.656, 95% CI 1.190-5.928, P = 0.01), higher HOMA index (OR 1.219, 95% CI 1.043-1.426, P = 0.01), and hyperuricemia (OR 4.906, 95% CI 1.683-14.296, P = 0.004) were linked to NAFLD activity score (NAS) ≥ 5 by multiple logistic regression analysis. Conversely, higher HOMA index (OR 1.140, 95% CI 1.001-1.229, P = 0.04), and NAS (OR1.954, 95% CI 1.442-2.649, P < 0.001) were independently associated with significant fibrosis by logistic regression analysis. In NAFLD patients, hyperuricemia is independently associated with the severity of liver damage, representing, in this setting of patients, together with insulin resistance, a potential new therapeutic target in future intervention trials.

Intervention of Selenium on Chronic Fluorosis-Induced Injury of Blood Antioxidant Capacity in Rats

This study was conducted to further explore the effects of selenium on the blood antioxidant capacity in rats exposed to fluoride to find out the optimal dosage level of selenium. Animals were divided into prevention sequence (Selenium → NaF, water → NaF) and treatment sequence (NaF → Selenium, NaF → water) (sodium fluoride 50mg/L; sodium selenite 0.375, 0.75, 1.5mg/L). The exposure time was 12months. Then, the fluidity of erythrocyte membrane by electron spin resonance was analyzed, and the blood was collected for GSH-Px and SOD activity, total antioxidant capacity (T-AOC) and uric acid assay, sialic acid and MDA content. The results showed that, compared with control group, GSH-Px activity and T-AOC level increased significantly (P < 0.05), and SOD activity was raised in varying degrees in prevention and treatment groups, respectively. Uric acid level was up-regulated, but no significant differences were observed (P > 0.05). The fluidity of erythrocyte membrane showed significant increase (P < 0.05). As evident in this study, when the dose of selenium was 0.75mg/L, all the activities of antioxidant enzymes increased significantly in prevention sequence; but in treatment sequence, the optimum intervention concentration was 1.5mg/L. On the basis of results, the preventive effect of selenium was superior to treatment effect on the oxidative stress induced by an overdose of fluoride.

Fluorescence modulation of 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione by silver nanoparticles and its possible analytical application

The effects of silver nanoparticles on the photophysical properties of 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, popularly known as curcumin, have been investigated using optical absorption and fluorescence techniques. Although absorption spectroscopy suggests a ground-state complex formation, fluorescence quenching data confirms a simultaneous static and dynamic quenching, inferring ground as well as excited-state complex formation. The recovery of fluorescence quenching of the curcumin-silver nanoparticle complex in the presence of ascorbic acid or uric acid emphasizes a strong interaction between the silver nanoparticles and ascorbic acid/uric acid, suggesting that fluorescence recovery after the quenching of curcumin-silver nanoparticle complexes has potential for ascorbic acid or uric acid assay development.

The utility of uric acid assay in dogs as an indicator of functional hepatic mass

Uric acid was used as a test for liver disease before the advent of enzymology. Three old studies criticised uric acid as a test of liver function. Uric acid, as an end-product of purine metabolism in the liver, deserved re-evaluation as a liver function test. Serum totalbile acids are widely accepted as the most reliable liver function test. This study compared the ability of serum uric acid concentration to assess liver function with that of serum pre-prandial bile acids in dogs. In addition, due to the renal excretion of uric acid the 2 assays were also compared in a renal disease group. Using a control group of healthy dogs, a group of dogs with congenital vascular liver disease, a group of dogs with non-vascular parenchymal liver diseases and a renal disease group, the ability of uric acid and pre-prandial bile acids was compared to detect reduced functional hepatic mass overall and in the vascular or parenchymal liver disease groups separately. Sensitivities, specificities and predictive value parameters were calculated for each test. The medians of uric acid concentration did not differ significantly between any of the groups, whereas pre-prandial bile acids medians were significantly higher in the liver disease groups compared with the normal and renal disease group of dogs. The sensitivity of uric acid in detecting liver disease overall was 65% while the specificity of uric acid in detecting liver disease overall was 59%. The sensitivity and specificity of uric acid in detecting congenital vascular liver disease was 68% and 59%, respectively. The sensitivity and specificity of uric acid in detecting parenchymal liver disease was 63% and 60%, respectively. The overall positive and negative predictive values for uric acid in detecting liver disease were poor and the data in this study indicated uric acid to be an unreliable test of liver function. In dogs suffering from renal compromise serum uric acid concentrations may increase into the abnormal range due to its renal route of excretion.

Enzyme-free colorimetric assay of serum uric acid

A nonenzymatic method for the selective detection and quantification of serum uric acid (UA) using 2-thiouracil (2-TU) tailored Au nanoparticles is developed. The H-bonding interaction of UA with functionalized Au nanoparticles brings instantaneous visible color change and paves the way for the visible sensing of UA.

Influence of selenium and fluoride on blood antioxidant capacity of rats

This study is to explore the effect of selenium and fluoride on blood antioxidant capacity of rats, and try to find out the optimal level of selenium in drinking water against fluorosis. Animals were divided into control group, sodium fluoride treated group (NaF, 50 mg/L) and selenium+NaF treated group (sodium selenite 0.375, 0.75, 1.5 mg/L) in water were respectively administered to male rats, which were decapitated after 6 months. Their blood was collected for GSH-Px activity, plasma SOD activity, T-AOC assay, uric acid assay, sialic acid (SA) content and MDA content, and the fluidity of erythrocyte membrane by electron spin resonance (ESR) was analyzed. The results showed that, compared with the control group, the blood antioxidant capacity of the rats exposed to fluoride was down-regulated significantly (P<0.05, P<0.01), MDA content increased significantly (P<0.05), the fluidity of erythrocyte membrane decreased (P<0.05, P<0.01). Meanwhile, the treatments of selenium along with NaF compared with fluorosis group, SOD activity, GSH-Px activity and T-AOC assay increased respectively, MDA content decreased significantly (P<0.05) in NaF+Se (Se 0.75, 1.5 mg/L) treated groups, uric acid level was up-regulated, but had no statistical significant difference (P>0.05). The fluidity of erythrocyte membrane showed significant increase (P<0.05), the content of SA was lower. Fluorosis could induce the decline of blood antioxidant capacity and the fluidity of erythrocyte membrane, as evident in this study, and Se at different levels possess some antagonistic effects on blood induced by fluoride. However, high dose of selenium (1.5 mg/L) is the optimum concentration.