Scoring system for diagnosis and pretreatment risk assessment of neuroblastoma using urinary biomarker combinations.

The urinary catecholamine metabolites, homovanillic acid (HVA) and vanillylmandelic acid (VMA), are used for the adjunctive diagnosis of neuroblastomas. We aimed to develop a scoring system for the diagnosis and pretreatment risk assessment of neuroblastoma, incorporating age and other urinary catecholamine metabolite combinations. Urine samples from 227 controls (227 samples) and 68 patients with neuroblastoma (228 samples) were evaluated. First, the catecholamine metabolites vanillactic acid (VLA) and 3-methoxytyramine sulfate (MTS) were identified as urinary marker candidates through comprehensive analysis using liquid chromatography-mass spectrometry. The concentrations of these marker candidates and conventional markers were then compared among controls, patients, and numerous risk groups to develop a scoring system. Participants were classified into four groups: control, low risk, intermediate risk, and high risk, and the proportional odds model was fitted using the L2-penalized maximum likelihood method, incorporating age on a monthly scale for adjustment. This scoring model using the novel urine catecholamine metabolite combinations, VLA and MTS, had greater area under the curve values than the model using HVA and VMA for diagnosis (0.978 vs. 0.964), pretreatment risk assessment (low and intermediate risk vs. high risk: 0.866 vs. 0.724; low risk vs. intermediate and high risk: 0.871 vs. 0.680), and prognostic factors (MYCN status: 0.741 vs. 0.369, histology: 0.932 vs. 0.747). The new system also had greater accuracy in detecting missing high-risk neuroblastomas, and in predicting the pretreatment risk at the time of screening. The new scoring system employing VLA and MTS has the potential to replace the conventional adjunctive diagnostic method using HVA and VMA.

A new three-dimensional (3D) molecularly imprinted polymer fluoroprobe based on green-red dual-emission signals of carbon quantum dots and self-polymerization of dopamine (CDs@PDA-MIPs) for sensitive detection of nifedipine.

Nifedipine (NIF), as one of the dihydropyridine calcium channel blockers, is widely used in the treatment of hypertension. However, misuse or ingestion of NIF can result in serious health issues such as myocardial infarction, arrhythmia, stroke, and even death. It is essential to design a reliable and sensitive detection method to monitor NIF. In this work, an innovative molecularly imprinted polymer dual-emission fluorescent sensor (CDs@PDA-MIPs) strategy was successfully designed for sensitive detection of NIF. The fluorescent intensity of the probe decreased with increasing NIF concentration, showing a satisfactory linear relationship within the range 1.0 × 10-6 M ~ 5.0 × 10-3 M. The LOD of NIF was 9.38 × 10-7 M (S/N = 3) in fluorescence detection. The application of the CDs@PDA-MIPs in actual samples such as urine and Qiangli Dingxuan tablets has been verified, with recovery ranging from 97.8 to 102.8% for NIF. Therefore, the fluorescent probe demonstrates great potential as a sensing system for detecting NIF.

A Novel Electrochemical Sensor Based on Pd Confined Mesoporous Carbon Hollow Nanospheres for the Sensitive Detection of Ascorbic Acid, Dopamine, and Uric Acid.

In this study, we designed a novel electrochemical sensor by modifying a glass carbon electrode (GCE) with Pd confined mesoporous carbon hollow nanospheres (Pd/MCHS) for the simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The structure and morphological characteristics of the Pd/MCHS nanocomposite and the Pd/MCHS/GCE sensor are comprehensively examined using SEM, TEM, XRD and EDX. The electrochemical properties of the prepared sensor are investigated through CV and DPV, which reveal three resolved oxidation peaks for AA, DA, and UA, thereby verifying the simultaneous detection of the three analytes. Benefiting from its tailorable properties, the Pd/MCHS nanocomposite provides a large surface area, rapid electron transfer ability, good catalytic activity, and high conductivity with good electrochemical behavior for the determination of AA, DA, and UA. Under optimized conditions, the Pd/MCHS/GCE sensor exhibited a linear response in the concentration ranges of 300-9000, 2-50, and 20-500 µM for AA, DA, and UA, respectively. The corresponding limit of detection (LOD) values were determined to be 51.03, 0.14, and 4.96 µM, respectively. Moreover, the Pd/MCHS/GCE sensor demonstrated outstanding selectivity, reproducibility, and stability. The recovery percentages of AA, DA, and UA in real samples, including a vitamin C tablet, DA injection, and human urine, range from 99.8-110.9%, 99.04-100.45%, and 98.80-100.49%, respectively. Overall, the proposed sensor can serve as a useful reference for the construction of a high-performance electrochemical sensing platform.

Sensing of Catecholamine in Human Urine Using a Simple Colorimetric Assay Based on Direct Melanochrome and Indolequinone Formation.

We used the first enzyme-free synthesis and stabilization of soluble melanochrome (MC) and 5,6-indolequinone (IQ) derived from levodopa (LD), dopamine (DA), and norepinephrine (NE) oxidation to develop a simple colorimetric assay for catecholamine detection in human urine, also elucidating the time-dependent formation and molecular weight of MC and IQ using UV-Vis spectroscopy and mass spectrometry. The quantitative detection of LD and DA was achieved in human urine using MC as a selective colorimetric reporter to demonstrate the potential assay applicability in a matrix of interest in therapeutic drug monitoring (TDM) and in clinical chemistry. The assay showed a linear dynamic range between 5.0 mg L-1 and 50.0 mg L-1, covering the concentration range of DA and LD found in urine samples from, e.g., Parkinson's patients undergoing LD-based pharmacological therapy. The data reproducibility in the real matrix was very good within this concentration range (RSDav% 3.7% and 6.1% for DA and LD, respectively), also showing very good analytical performances with the limits of detection of 3.69 ± 0.17 mg L-1 and 2.51 ± 0.08 mg L-1 for DA and LD, respectively, thus paving the way for the effective and non-invasive monitoring of dopamine and levodopa in urine from patients during TDM in Parkinson's disease.

Dual-mode detection of dopamine based on 0D/2D/2D CuInS2/ZnS quantum dot-black phosphorous nanosheet-TiO2 nanosheet nanocomposites.

In this work, we designed new dual-mode "turn-on" electrochemical (EC) and photoelectrochemical (PEC) sensors for the detection of dopamine (DA) based on 0D/2D/2D CuInS2/ZnS quantum dot (QD)-black phosphorous nanosheet (BPNS)-TiO2 nanosheet (TiO2NS) nanocomposites. QDs can not only improve the photocurrent of the developed PEC sensors, but also provide the electrochemical signal in the EC detection. BPNSs as p-type semiconductor with high conductive properties work as electron acceptors and are utilized to improve the sensitivity of the DA PEC and EC sensors. Under irradiation of visible light or the applied voltage, DA is both excited and releases electrons, realizing "turn-on" detection. The PEC sensors have a linear range of 0.1-100 µM with a lower detection limit of 0.028 µM. For the EC detection, BPNSs can accelerate electron transfer which attribute to its excellent conductivity. In the range of 1-200 µM, the working curve of DA detection by the EC sensors was established and the detection limit is 0.88 µM. Comparing the two methods, the PEC sensors have a lower detection limit, and the EC sensors have a wider monitoring range. The dual-mode sensors of EC and PEC pave an effective way for the detection in biological and medical fields.

The effect of acid use as a preservative on the results of biochemical tests measured in 24-h urine.

Twenty-four-hour urine measurements play a crucial role in the diagnosis, follow-up and treatment of various diseases. There are different approaches to the collection of urine in patients who need to collect multiple urine samples at a time, especially in hospitals with heavy workloads. In this study, we compared the sodium, potassium, chloride, amylase, calcium, creatinine, phosphorus, microalbumin, protein, magnesium, urea, uric acid, adrenaline, noradrenaline, dopamine, metanephrine, normetanephrine, vanillylmandelic acid, 5-hydroxyindoleacetic acid and homovanillic acid results of 24-h urine samples analyzed immediately without acid addition, which we accepted as the reference and baseline measurement, with the results of the samples analyzed after waiting for 24 h without acid addition, analyzed immediately with acid addition and analyzed after waiting for 24 h with acid addition. Chloride, microalbumin, amylase and protein tests, which are recommended to be measured in the sample without preservatives, are affected by acid addition. Adrenaline, noradrenaline and dopamine, which are the tests recommended to be measured in acid-added urine are degraded in the samples without acid, and the levels of metanephrine and normetanephrine were not significantly degraded in the absence of preservatives.

Clinical utility of urinary levels of catecholamines and their fraction ratios related to heart rate and thyroid function.

Urinary catecholamines (CAs) have been examined for the screening of pheochromocytomas. The decision to perform screening is based on symptoms suggesting secondary hypertension or hyperactivities of the sympathetic nervous system. To elucidate the usefulness of urinary fractions and ratios of CAs, 79 patients in whom 24-h excretions of urinary CAs including adrenaline (AD), noradrenaline (NA) and dopamine (DA) had been examined from 2015 until 2020 were retrospectively analyzed. There were no significant differences in urinary CA levels between two age groups, gender groups and two BMI groups. Patients with histories of preexisting hypertension and diabetes showed significantly higher levels of urinary NA excretion, and the urinary ratio of NA/DA was also increased in the patients with a history of hypertension. Heart rate (HR) was significantly correlated with the urinary ratio of NA/DA. Serum free thyroxine (FT4) concentration and ratio of FT4/thyrotropin (TSH) were correlated with the level of urinary AD. The levels of TSH and FT4/TSH showed negative and positive correlations, respectively, with the urinary NA/DA ratio. Thus, increases of HR are related to the enhanced conversion of DA to NA and increased thyroid hormones are involved in the increase in urinary AD and the conversion of DA to NA. History of lifestyle-related diseases and changes of HR and thyroid functions need to be considered for the evaluation of urinary CAs and their ratios.

Loading-induced antitumor capability of murine and human urine.

While urine has been considered as a useful bio-fluid for health monitoring, its dynamic changes to physical activity are not well understood. We examined urine's possible antitumor capability in response to medium-level, loading-driven physical activity. Urine was collected from mice subjected to 5-minute skeletal loading and human individuals before and after 30-minute step aerobics. Six cancer cell lines (breast, prostate, and pancreas) and a mouse model of the mammary tumor were employed to evaluate the effect of urine. Compared to urine collected prior to loading, urine collected post-activity decreased the cellular viability, proliferation, migration, and invasion of tumor cells, as well as tumor weight in the mammary fat pad. Detection of urinary volatile organic compounds and ELISA assays showed that the loading-conditioned urine reduced cholesterol and elevated dopamine and melatonin. Immunohistochemical fluorescent images presented upregulation of the rate-limiting enzymes for the production of dopamine and melatonin in the brain. Molecular analysis revealed that the antitumor effect was linked to the reduction in molecular vinculin-linked molecular force as well as the downregulation of the Lrp5-CSF1-CD105 regulatory axis. Notably, the survival rate for the high expression levels of Lrp5, CSF1, and CD105 in tumor tissues was significantly lowered in the Cancer Genome Atlas database. Collectively, this study revealed that 5- or 10-minute loading-driven physical activity was sufficient to induce the striking antitumor effect by activating the neuronal signaling and repressing cholesterol synthesis. The result supported the dual role of loading-conditioned urine as a potential tumor suppressor and a source of diagnostic biomarkers.

Early pregnancy metabolites predict gestational diabetes mellitus: implications for fetal programming.

BACKGROUND: Aberrant fetal programming in gestational diabetes mellitus seems to increase the risk of obesity, type 2 diabetes, and cardiovascular disease. The inability to accurately identify gestational diabetes mellitus in the first trimester of pregnancy has thwarted ascertaining whether early therapeutic interventions reduce the predisposition to these prevalent medical disorders. OBJECTIVE: A metabolomics study was conducted to determine whether advanced analytical methods could identify accurate predictors of gestational diabetes mellitus in early pregnancy. STUDY DESIGN: This nested observational case-control study was composed of 92 gravidas (46 in the gestational diabetes mellitus group and 46 in the control group) in early pregnancy, who were matched by maternal age, body mass index, and gestational age at urine collection. Gestational diabetes mellitus was diagnosed according to community standards. A comprehensive metabolomics platform measured 626 endogenous metabolites in randomly collected urine. Consensus multivariate criteria or the most important by 1 method identified low-molecular weight metabolites independently associated with gestational diabetes mellitus, and a classification tree selected a subset most predictive of gestational diabetes mellitus. RESULTS: Urine for both groups was collected at a mean gestational age of 12 weeks (range, 6-19 weeks' gestation). Consensus multivariate analysis identified 11 metabolites independently linked to gestational diabetes mellitus. Classification tree analysis selected a 7-metabolite subset that predicted gestational diabetes mellitus with an accuracy of 96.7%, independent of maternal age, body mass index, and time of urine collection. CONCLUSION: Validation of this high-accuracy model by a larger study is now needed to support future studies to determine whether therapeutic interventions in the first trimester of pregnancy for gestational diabetes mellitus reduce short- and long-term morbidity.

A covalent organic polymer-TiO2/Ti3C2 heterostructure as nonenzymatic biosensor for voltammetric detection of dopamine and uric acid.

Heterostructures have potential to blend the advantages of each material, even exhibiting the evolutionary performance due to synergistic effects. Herein, covalent organic polymers (NUF) are integrated with a TiO2/Ti3C2Tx nanocomposite (TiO2/TiCT) to form TiO2/TiCT-NUF heterojunctions as an enlarged nonenzymatic biosensor for dopamine (DA) and uric acid (UA). Detection is performed by differential pulse voltammetry (DPV). The TiO2/TiCT/NUF exhibits high sensing activity with low detection limits of 0.2 and 0.18 nM (S/N = 3) in the concentration ranges from 0.002 to 100 µM and 0.001 to 60 µM for simultaneous determination of DA and UA, respectively. In addition, the TiO2/TiCT/NUF provides good selectivity and reproducibility for DA and UA detection in urine and serum samples with recoveries of 98.4 to 100.9%. The proposed heterojunctions manifest an intriguing potential as a candidate of an electrochemical sensor for sole and simultaneous detection of DA and UA.

Effect of Exhaustive Training or Forced Immobilization on Physiological Condition and Main Metabolic and Stress Markers of Wistar Male Rats.

For correct and reliable experimental in vivo assessment of antistress effect of various bioactive substances, appropriate biomodels reproducing stress and organism response to stress in laboratory animals should be chosen. We chose treadmill test for simulating exhaustive physical load and forced immobilization accompanied by disorders of physiological and psychological condition. Verification of the models used indicates their wide applicability for testing certain biological manifestations under reproduced stress exposure.

Lateral flow assay using aptamer-based sensing for on-site detection of dopamine in urine.

A lateral flow assay using DNA aptamer-based sensing for the detection of dopamine in urine is reported. Dopamine duplex aptamers (hybridized sensor with capture probe) are conjugated to 40-nm Au nanoparticles (AuNPs) with 20T linkers. The detection method is based on the dissociation of the duplex aptamer in the presence of dopamine, with the sensor part undergoing conformational changes and being released from the capture part. Hybridization between the complementary DNA in the test line and the conjugated AuNP-capture DNA produces a red band, whose intensity is related to the dopamine concentration. The minimum detectable concentration obtained by ImageJ analysis was <10 ng/mL (65.2 nM), while the visual limit of detection is estimated to be ~50 ng/mL (normal range of dopamine in urine of 52-480 ng/mL or 0.3-3.13 µM). No cross reactivity to other stress biomarkers in urine was confirmed. These results indicate that this robust and user-friendly point-of-care biosensor has significant potential for providing a cost-effective alternative for dopamine detection in urine.

Label-free liquid crystal-based biosensor for detection of dopamine using DNA aptamer as a recognition probe.

We present a label-free liquid crystal-based biosensor for the detection of dopamine (DA) in aqueous solutions using dopamine-binding aptamers (DBA) as recognition elements. In this system, the dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DMOAP) self-assembled monolayers immobilized on glass slides support the long alkyl chains that keep the liquid crystal (LC) molecules in a homeotropic orientation. Glutaraldehyde (GA) is used as a cross-linker to immobilize DBA onto the surface of glass slides. The specific binding of DA and DBA disrupts the homeotropic orientation of LCs, thereby inducing a change in the orientation from homeotropic to a random alignment. This orientation change can be converted and visualized simply as a transition from a dark optical LC image to a brighter image under a polarized optical microscope (POM), enabling the detection of DA. The developed LC-based aptasensor shows a good linear optical response towards DA in the very wide range of 1 pM-10 µM (0.19 pg/mL to 1.9 µg/mL) and has a very low detection limit of 10 pM (∼1.9 pg/mL). The biosensor also exhibited satisfactory selectivity and could be successfully applied to detect DA in human urine. The proposed LC-based aptamer sensing method offers a simple, rapid, highly sensitive and selective, and a label-free method for the analysis of DA in real clinical samples.

Silver nanocube coupling with a nanoporous silver film for dual-molecule recognition based ultrasensitive SERS detection of dopamine.

Dopamine (DA) is one of the catecholamine neurotransmitters used for the treatment of neural disorders. In this study, a novel sensor based on surface-enhanced Raman scattering (SERS) with dual molecule-recognition for ultrasensitive detection of DA was presented, with a limit of detection (LOD) of 40 fM, without any pretreatment of clinical samples. To realize the sensitive and selective detection of DA in complex samples, the nanoporous silver film (AgNF) surfaces were functionalized with mercaptopropionic acid (MPA) to accurately capture DA, while silver nanocubes (AgNCs) were modified with 4-mercaptobenzene boronic acid (4-MPBA) as a Raman reporter for the quantitative detection of DA. The nanogaps between AgNCs and the AgNF led to the generation of an abundance of hot spots for the SERS signal and thus effectively improved the sensitivity of DA detection. Measurements of DA concentrations in clinical body fluids such as human serum and urine samples are also demonstrated, showing excellent performance for DA detection in a complex environment. Our results demonstrate the promising potential for the ultrasensitive detection of DA for the potential diagnosis of DA-related diseases.

Nanocomposites of poly(l-methionine), carbon nanotube-graphene complexes and Au nanoparticles on screen printed carbon electrodes for electrochemical analyses of dopamine and uric acid in human urine solutions.

A sensitive electrochemical sensor featuring novel composites of gold and carbon nanocomplexes alongside a polymerized amino acid was developed for the determination of uric acid (UA) and dopamine (DA) concentrations in both buffer and human urine sample solutions. The sensor was fabricated by electropolymerization of l-methionine (l-Met) followed by coating of carbon nanotube-graphene complexes and electrodeposition of gold nanoparticles on a screen printed carbon electrode surface. The electrode surfaces were characterized by field emission scanning electron microscopy and energy dispersive spectroscopy, and the electrochemical properties were investigated by cyclic voltammetry and differential pulse voltammetry. Linear ranges of 0.05-3 µM and 1-35 µM with limits of detection of 0.0029 and 0.034 µM were achieved for DA and UA, respectively. In addition, the developed sensor was applied for the analysis of native UA and DA concentrations in undiluted and diluted human urine samples. The UA analysis results were compared to those obtained using high performance liquid chromatography and a fluorometric assay kit while the DA analysis results were compared to those obtained using liquid chromatography-tandem mass spectrometry.

Dopamine-induced photoluminescence quenching of bovine serum albumin-capped manganese-doped zinc sulphide quantum dots.

The direct detection of dopamine (DA) in human body fluids is a great challenge for medical diagnostics of neurological disorders like Parkinson's disease, Alzheimer's disease, senile dementia, and schizophrenia. In this work, a simple and turn off luminescence sensing of DA based on bovine serum albumin (BSA)-capped manganese-doped zinc sulphide quantum dots (Mn:ZnS/BSA QDs) is developed. The Mn:ZnS/BSA QDs were synthesized by a chemical co-precipitation method. Due to the special interaction of DA with BSA and metal ions, Mn:ZnS/BSA QDs can serve as an effective sensing platform for DA. The luminescence of Mn:ZnS/BSA QDs decreased linearly with increasing concentration of DA in the range from 6.6 to 50.6 nM. The limit of detection is 2.02 nM. The driving force for the luminescence quenching is partly provided by ground-state complex formation of QDs with DA. The photo-induced electron transfer from the conduction band of QDs to oxidized dopamine (quinone) also favors quenching. The Mn:ZnS/BSA QDs are barely interfered with by other competing biomolecules except catecholamine neurotransmitter like epinephrine. Moreover, this method is used in the analysis of DA-spiked human serum and human urine samples and good recovery percentages are found. To assess the utility of the developed sensor, paper strip assay was also successfully conducted. Graphical abstract.

Identification of markers of depression and neurotoxicity in pesticide exposed agriculture workers.

Earlier, we reported that chronic exposure to pesticides causes a reduction in the acetylcholinesterase activity and hematological and biochemical alterations in agriculture workers. In continuation with that, the present study aimed to investigate the pesticide-induced neurochemical imbalance and its association with behavior alterations in agricultural workers. A significant increase in depressive symptoms, assessed by the Beck Depression Inventory-II was observed in pesticide exposed workers as compared to the unexposed. A decrease in the level of dopamine in plasma and levels of dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acids, norepinephrine, serotonin, and hydroxyindoleacetic acid in urine was also observed. An increase in the levels of MAO-A and MAO-B has also been observed in these individuals. The decreased levels of neurotransmitters in the blood and urine have been linked with increased levels of MAO and pesticide residues in plasma and urine. Furthermore, these changes were associated with a higher incidence of depression in agricultural workers.

Simultaneous and sensitive determination of ascorbic acid, dopamine and uric acid via an electrochemical sensor based on PVP-graphene composite.

A method with high sensitivity, good accuracy and fast response is of ever increasing importance for the simultaneous detection of AA, DA and UA. In this paper, a simple and sensitive electrochemical sensor, which based on the polyvinylpyrrolidone (PVP)-graphene composite film modified glassy carbon electrode (PVP-GR/GCE), was presented for detecting ascorbic acid (AA), dopamine (DA) and uric acid (UA) simultaneously. The PVP-GR/GCE has excellent electrocatalytic activity for the oxidation of AA, DA and UA. The second-order derivative linear sweep voltammetry was used for the electrochemical measurements. The peak potential differences of DA-AA, DA-UA, and UA-AA (measured on the PVP-GR/GCE) were 212, 130 and 342 mV respectively. Besides, the over potential of AA, DA and UA reduced obviously, so did the peak current increase. Under the optimum conditions, the linear ranges of AA, DA and UA were 4.0 µM-1.0 mM, 0.02-100 µM, and 0.04-100 µM, respectively. The detection limits were 0.8 µM, 0.002 µM and 0.02 µM for AA, DA, and UA. The electrochemical sensor presented the advantages of high sensitivity and selectivity, excellent reproducibility and long-term stability. Furthermore, the sensor was successfully applied to the analysis of real samples.

Electrochemical sensor based on CuSe for determination of dopamine.

A simple binary copper selenide, CuSe nanostructure, has been investigated as electrochemical sensor for dopamine detection. The hydrothermally synthesized and electrodeposited CuSe nanostructures showed high sensitivity for dopamine detection with low limit of detection (LOD). A sensitivity of 26 µA/µM.cm2 was obtained with this electrochemical sensor which is ideal to detect even small fluctuations in the transient dopamine concentration. Apart from high sensitivity and low LOD, the dopamine oxidation on the catalyst surface also occurred at a low applied potential (< 0.18 V vs Ag|AgCl), thereby significantly increasing selectivity of the process specifically with respect to ascorbic and uric acids, which are considered to be the most prominent interferents for dopamine detection. Electrochemical redox tunability of the catalytic Cu center along with low coordination geometry is believed to enhance the rate of dopamine attachment and oxidation on the catalyst surface thereby reducing the applied potential. The presence of Cu also increases conductivity of the catalyst composite which further improves the charge transfer thus increasing the sensitivity of the device. This is the first report of electrochemical dopamine sensing with a simple binary selenide comprising earth-abundant elements and can have large significance in designing efficient sensors that can be transformative for understanding neurodegenerative diseases further. Graphical abstract.

Photo-electrochemical detection of dopamine in human urine and calf serum based on MIL-101 (Cr)/carbon black.

A new photo-electrochemical sensor based on MIL-101(Cr) MOF/carbon black (CB) is fabricated and characterized. By using differential pulse voltammetry, dopamine (DA) can be effectively detected using a photo-electrochemical MIL-101(Cr)/CB sensor under visible light. The CB acts as the electron bridge to combine with the large specific surface area and photo-catalytic feature of MOF, which contribute to the improvements of sensitivity of DA detection. The concentration of the catalyst, pH value, accumulation potential, and accumulation time were also optimized. Furthermore, the electrochemical performances of MIL-101(Cr)/CB sensor was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scan rate, electrochemically active surface area (ECSA), and amperometric responses. A detection limit of 0.38 nM (LOD = 3 sb/S, sb = 0.028) and a working range of 1 nM to 2.22 µM has been achieved. The MIL-101(Cr)/CB sensor exhibits excellent reproducibility, stability, and selectivity and also has satisfactory recovery rate for the analysis of real samples including calf serum and human urine. Graphical abstract.