Artificial Urine Samples Research Articles

Combination of spraying based liquid phase microextraction and liquid chromatography–tandem mass spectrometry for the determination of colchicine at ultra–trace levels in artificial urine and serum samples

Combination of spraying based liquid phase microextraction and liquid chromatography–tandem mass spectrometry for the determination of colchicine at ultra–trace levels in artificial urine and serum samples

PolyCitrulline Modified Glassy Carbon Electrode as a Voltammetric Sensor for the Simultaneous Determination of Metabolic Syndrome Biomarkers-Uric Acid and Tyramine

Abstract This article describes the development of a simple and sensitive voltammetric sensor for the simultaneous determination of Uric acid (UA) and Tyramine (TYM), which act as metabolic syndrome (Mts) biomarkers. The electropolymer of the naturally occurring amino acid citrulline (Cit) has been employed as the electrode modifier in this sensor. Glassy carbon electrode modified with poly citrulline has been characterized with the aid of techniques such as scanning electron microscopy (SEM) and SEM-energy dispersive X-ray analysis, surface area calculations and electrochemical impedance spectroscopy. Studies were carried out to optimize parameters like the cycles of polymerisation, supporting electrolyte and its pH. The sensor which offers fast determination of the analytes using square wave voltammetry possesses a limit of detection 1.32×10-8 M and 4.20×10-8 M for UA and TYM, respectively. The applicability of the sensor in body fluids has been proved through spike recovery analysis in artificial blood serum and urine samples. Interference on the voltammetric signals created by some dominant coexisting species of the analytes was found to be tolerable.

Enhancing Pregnancy Care: Harnessing Label‐Free Immunosensors for Pre‐Eclampsia Detection Using PdNPs/Poly(3,5‐Diaminobenzoic Acid) Modified Glassy Carbon Electrodes

AbstractPlacental Growth factor (PlGF) is one of the biomarkers useful for detecting pregnancy hypertension disorder, Pre‐eclampsia. Herein, we focus on developing a label‐free immunosensor using simple electrochemical methods to detect PlGF antigens for pre‐eclampsia diagnosis. The work includes the electrochemical deposition of Palladium nanoparticles (PdNPs) on the glassy carbon electrode (GCE) surface using amperometry followed by electropolymerization of diaminobenzoic acid (DABA) onto the PdNPs/GCE. Antibody (aPlGF) was covalently immobilized on the pDABA/PdNPs/GCE using EDC/NHS reaction. The interaction of the antibody with the antigen was measured using differential pulse voltammetric technique. The linear range obtained for the immunosensor is 1–25 ng mL−1 with a limit of detection of 53 pg mL−1. The stability and reproducibility of the sensor were obtained in the acceptable range. The developed sensor was used to detect PlGF antigen in artificial blood and urine samples by spike recovery analysis.

Multi-walled carbon nanotubes functionalized with a new Schiff base containing phenylboronic acid residues: applicationtothe development of a bienzymatic glucose biosensor using a response surface methodology approach.

Aninnovative supramolecular architectureis reportedfor bienzymatic glucose biosensing based on the use of a nanohybrid made of multi-walled carbon nanotubes (MWCNTs) non-covalently functionalized with a Schiff base modified with two phenylboronic acid residues (SB-dBA) as platform for the site-specific immobilization of the glycoproteins glucose oxidase (GOx) and horseradish peroxidase (HRP). The analytical signal was obtained from amperometric experiments at - 0.050V in the presence of 5.0 × 10-4M hydroquinone as redox mediator. The concentration of GOx and HRP and the interaction time between the enzymes and the nanohybrid MWCNT-SB-dBA deposited at glassy carbon electrodes (GCEs) were optimized through a central composite design (CCD)/response surface methodology (RSM). The optimal concentrations of GOx and HRP were 3.0mgmL-1 and 1.50mgmL-1, respectively, while the optimum interaction time was 3.0min. The bienzymatic biosensor presented a sensitivity of (24 ± 2) × 102 µA dL mg-1 ((44 ± 4) × 102 µA M-1), a linear range between 0.06mg dL-1 and 21.6mg dL-1 (3.1µM-1.2mM) (R2 = 0.9991),and detection and quantification limits of 0.02mg dL-1 (1.0µM) and 0.06mg dL-1 (3.1µM), respectively. The reproducibility for five sensors prepared with the same MWCNT-SB-dBA nanohybrid was 6.3%, while the reproducibility for sensors prepared with five different nanohybrids and five electrodes each was 7.9%. The GCE/MWCNT-SB-dBA/GOx-HRP was successfully used for the quantification of glucose in artificial human urine and commercial human serum samples.

Embroidered textile-based electrochemical sensors towards urinary nitrite measurement

Wearable biochemical sensors enable the real-time measurement of health parameters in non-invasive manner. In this work, we have developed polyaniline (PANI)/COOH-functionalized multiwalled carbon nanotubes (MWCNTs)/sodium copper chlorophyllin (CuCP) coated conductive thread as a novel wearable platform for monitoring nitrite (NO2–) levels. The linear calibration plots for NO2– were obtained over the concentration range of 0.05 µM–10 mM with detection limit of 0.35 nM. The sensor platform was also tested for measuring NO2– levels in artificial urine samples.

Development of An Eco-Friendly and Cost-Effective Electrochemical Sensor for the Simultaneous Detection of Dopamine and Serotonin

An electrochemical sensor based on eco-friendly green synthesized silver nanoparticles decorated reduced graphene oxide (AgNPs-rGO) modified screen-printed carbon electrode (SPCE) for the simultaneous detection of serotonin (5-HT) and dopamine (DA) is reported for the first time. The experimental parameters affecting the sensor performance were optimized in terms of AgNPs-rGO coating amount, scan rate and electrolyte pH (6–8). Under optimal conditions, the AgNPs-rGO/SPCE was employed to individually determine both analytes using DPV technique. The sensor was also efficient in the simultaneous detection of these species and reported well-resolved oxidation peaks with a linear range of 10–100 μM and detection limits of 7 μM and 7.41 μM, respectively. The developed device showed good selectivity, reproducibility, and repeatability. Furthermore, it was successfully applied to the determination of both biomolecules in artificial urine samples with good recovery. The main advantages of the designed sensor are its simplicity, portability, and low cost.

2D-network of boron-functionalized N-doped graphene quantum dots for electrochemical sensing of dopamine

A glassy carbon electrode (GCE) modified by boron-functionalized N-doped graphene quantum dots (B-GQDs) was employed for the electrochemical determination of dopamine (DA), a neurotransmitter. The B-GQDs were obtained by hydrothermal etching of GO with H2O2 and NH3 in the presence of H3BO3. By using various techniques, including transmission electron microscopy, atomic force microscopy, molecular absorption spectrometry, fluorescence, ICP-MS, and zeta potential analysis, it was demonstrated that B-GQDs are self-organized in 2D-network, being N-doped GQDs nanoparticles crosslinked by H3BO3. The GCE modification was carried out using the drop-casting method with B-GQDs in Nafion®, previously dispersed through ultrasonication. For the first time, the synthesized nanomaterial was tested in the electroanalysis of neurotransmitters. The B-GQDs/Nafion®/GCE modification led to a significant increase in peak currents in the presence of DA. The electrochemical and interfacial characteristics of the sensors were evaluated by cyclic voltammetry (CV). Under optimized square wave voltammetry and supporting electrolyte conditions, a linear dependence between the anodic peak current and DA concentration was observed in the range of 0.7 to 188 μmol L−1 (R2 = 0.9991). The limit of detection (LOD) was estimated at 0.05 μmol L−1. Selectivity was confirmed in the presence of potential interferents found in urine, with interference response below 12 %. The sensor exhibited excellent intra-day and inter-day repeatability, with a relative standard deviation of 4.12 % and 4.66 %, respectively. Electrochemical determination of DA was conducted in artificial urine samples (Surine®), with recovery values of 90–101 %. The new analytical platform B-GQDs/Nafion®/GCE demonstrated promising characteristics for application in biological and/or pharmaceutical analysis.

Determination of Acetylamantadine by γ-Cyclodextrin-Assisted α-HL Nanopore for Potential Cancer Prediagnosis.

The high expression of Spermidine/spermine N1-acetyltransferase (SSAT-1) is an important indicator in early cancer diagnosis. Here, we developed a nanopore-based methodology with γ-cyclodextrin as an adaptor to detect and quantify acetylamantadine, the specific SSAT-1-catalyzed product from amantadine, to accordingly reflect the activity of SSAT-1. We employ γ-cyclodextrin and report that amantadine cannot cause any secondary signals in γ-cyclodextrin-assisted α-HL nanopore, while its acetylation product, acetylamantadine, does. This allows γ-cyclodextrin to practically detect acetylamantadine in the interference of excessive amantadine, superior to the previously reported β-cyclodextrin. The quantification of acetylamantadine was not interfered with even a 50-fold amantadine and displayed no interference in artificial urine sample analysis, which indicates the good feasibility of this nanopore-based methodology in painless cancer prediagnosis. In addition, the discrimination mechanism is also explored by 2-D nuclear magnetic resonance (NMR) and nanopore experiments with a series of adamantane derivatives with different hydrophilic and hydrophobic groups. We found that both the hydrophobic region matching effect and hydrophilic interactions play a synergistic effect in forming a host-guest complex to further generate the characteristic signals, which may provide insights for the subsequent design and study of drug-cyclodextrin complexes.

The future of drug Monitoring: Highly selective ratiometric sensing of mefenamic acid by simple AIEE active probe supported through Extensive fluorometric and DFT studies

Over intake of mefenamic acid (MA) cause morbidity, mortality, liver damage, and hepatic necrosis. For this reason, it is of great importance to discover novel methodologies that provide sharp detection timing, improved sensing efficiency, and profound reproducibility in MA detection. In our current research, we synthesized a naphthalic anhydride based probe PPN which revealed excellent sensing potential towards MA. Probe PPN exhibited ratiometric fluorescence against MA based on complex formation and photoinduced electron transfer (PET) process. Detection mechanism was verified through Density functional theory (DFT) calculations and 1H NMR titration experiments. The type of interaction between probe PPN and MA was investigated through quantum theory of atoms in molecules (QTAIM) analysis and noncovalent interaction (NCI) analysis and was further evaluated via spectroscopic analysis. Moreover, the probe PPN was practically employed to the sensing of MA in artificial urine, pharmaceutical wastewater, and blood samples. Probe PPN is the most streamlined probe designed ever for the sensing of MFA in complex environments with extreme selectivity and sensitivity.

Smartphone-Based Point-of-Care Urinalysis Vivoo App: A Validation Study

Point-of-care (POC) analysis has emerged as a pivotal approach in providing rapid and convenient medical diagnostics. Smartphone-based solutions further augment the accessibility and ease of POC, enabling efficient on-the-go analysis. The integration of smartphone technology with POC has paved the way for innovative applications such as the Vivoo App, which empowers users to monitor various health parameters conveniently. Our study validated the accuracy and reliability of the smartphone-based POC urinalysis Vivoo mobile application. A comparative approach was followed wherein artificial urine samples were analyzed using both the Vivoo and traditional laboratory methods. A diverse range of health parameters were assessed. A total of 2618 strips were used over the course of this study to evalate the accuracy of Vivoo. The test strips results appeared to match exactly the expected measurement results. In addition, when the ±1 color block acceptance criterion was applied, 2608 of 2618 measurements of the tested strips were found to have met the expected measurement results completely. Based on the results, the 95% confidence interval for the exact match agreement proportion of Vivoo is 87.55% ± 1.27% and 99.62% ± 0.24%. As a wellness product, this study thus concludes that the Vivoo is appropriate in terms of both device reliability and performance. The app's ability to provide accurate and timely health results offers promising opportunities to improve individual health management.

Direct fluorescence and spectrophotometric-based detection of azithromycin using fluorescein isothiocyanate: Method development and comparative analysis

New methods for the analysis of azithromycin (AZM) have been devised, employing direct fluorescence and spectrophotometric techniques. This research focused on the development and validation of these methods, especially based on the formation of an ion-pair complex with fluorescein isothiocyanate (FITC). The resulting complex enhanced the fluorescence intensity at a wavelength of 520 nm and the absorbance at 480 nm. The impact of different solvent compositions was investigated, with methanol and a 1:1 mixture of methanol and Milli-Q proving to be the most sensitive. The optimal FITC concentration was determined as 50 µg/ml, and the molar ratio of the AZM-FITC ion-pair complex was determined to be 1:1. Notably, an instantaneous increase in fluorescence intensity was observed, eliminating the need for incubation. The developed methods were validated for sensitivity, accuracy, and precision, with the fluorescence-based method demonstrating superior sensitivity and precision compared to the spectrophotometric method. Under optimum conditions, the fluorescence-based method achieved a linear range of 0–31.25 µg/ml with a limit of detection (LOD) of 0.41 µg/ml and a limit of quantification (LOQ) of 1.23 µg/ml., In contrast, the spectrophotometric method had an LOD of 0.82 µg/ml and an LOQ of 2.49 µg/ml. Additionally, the fluorescence-based method exhibited a narrower recovery range in artificial urine samples, suggesting higher precision in complex matrices. Overall, these methods offer rapid and sensitive AZM analysis with potential applications in diverse matrices such as biological samples post-extraction.

Electrochemical Determination of Fentanyl Using Carbon Nanofiber-Modified Electrodes.

In this work, we report the direct electrochemical oxidation of fentanyl using commercial screen-printed carbon electrodes (SPCEs) modified with carboxyl-functionalized carbon nanofibers (fCNFs). CNFs have surface chemistry and reactivity similar to carbon nanotubes (CNTs), yet they are easier to produce and are of a lower cost than CNTs. By monitoring the current produced during the electrochemical oxidation of fentanyl, variables such as fCNF loading, fentanyl accumulation time, electrolyte pH, and differential pulse voltammetry parameters were optimized. Under an optimized set of conditions, the fCNF/SPCEs responded linearly to fentanyl in the concentration range of 0.125-10 μM, with a limit of detection of 75 nM. The fCNF/SPCEs also demonstrated excellent selectivity against common cutting agents found in illicit drugs (e.g., glucose, sucrose, caffeine, acetaminophen, and theophylline) and interferents found in biological samples (e.g., ascorbic acid, NaCl, urea, creatinine, and uric acid). The performance of the sensor was also successfully tested using fentanyl spiked into an artificial urine sample. The straightforward electrode assembly process, low cost, ease of use, and rapid response make the fCNF/SPCEs prime candidates for the detection of fentanyl in both physiological samples and street drugs.

Rapid Near-Patient Impedimetric Sensing Platform for Prostate Cancer Diagnosis.

With the global escalation of concerns surrounding prostate cancer (PCa) diagnosis, reliance on the serologic prostate-specific antigen (PSA) test remains the primary approach. However, the imperative for early PCa diagnosis necessitates more effective, accurate, and rapid diagnostic point-of-care (POC) devices to enhance the result reliability and minimize disease-related complications. Among POC approaches, electrochemical biosensors, known for their amenability and miniaturization capabilities, have emerged as promising candidates. In this study, we developed an impedimetric sensing platform to detect urinary zinc (UZn) in both artificial and clinical urine samples. Our approach lies in integrating label-free impedimetric sensing and the introduction of porosity through surface modification techniques. Leveraging a cellulose acetate/reduced graphene oxide composite, our sensor's recognition layer is engineered to exhibit enhanced porosity, critical for improving the sensitivity, capture, and interaction with UZn. The sensitivity is further amplified by incorporating zincon as an external dopant, establishing highly effective recognition sites. Our sensor demonstrates a limit of detection of 7.33 ng/mL in the 0.1-1000 ng/mL dynamic range, which aligns with the reference benchmark samples from clinical biochemistry. Our sensor results are comparable with the results of inductively coupled plasma mass spectrometry (ICP-MS) where a notable correlation of 0.991 is achieved. To validate our sensor in a real-life scenario, tests were performed on human urine samples from patients being investigated for prostate cancer. Testing clinical urine samples using our sensing platform and ICP-MS produced highly comparable results. A linear correlation with R2 = 0.964 with no significant difference between two groups (p-value = 0.936) was found, thus confirming the reliability of our sensing platform.

Bimetallic FeOx-TiO2@Carbon hybrid structure materials with notable peroxidase enzyme mimics applied toone-step colorimetric detection of glucose.

FeOx-TiO2@Carbon hybrid structure materials (FeOx-TiO2@CHs) with high peroxidase (POD)-like activity have been preparedby one-pot hydrothermal method. Based on the excellent POD activity of FeOx-TiO2@CHs, one pot colorimetric detection for glucose was constructed by using TMB as substrate with the synergistic reaction of glucose oxidase; the linear range and the limit of detection (LOD) are 25 ~ 1000 and 1.77µM, respectively. Using this method, the glucose in serum real samples was detected with satisfactory results, and the results are consistent with that of the glucometer method in the hospital. The recovery in diabetic and artificial urine samples was 95.71 ~ 104.67% and 99.01 ~ 103.16%, respectively. Themechanism of the catalytic colorimetric reaction was also investigated by multiple measurements, and the results indicated that superoxide anions (O2•-) between FeOx-TiO2@CHs and substrate play a main role, but a small quantity of hydroxyl radical •OH and singlet oxygen 1O2 is also generated simultaneously. The one-pot reaction method is simple and fast; the detection process only requires a simple mixing, which is suitable for application in special environment.

Flow-Through Amperometric Biosensor System Based on Functionalized Aryl Derivative of Phenothiazine and PAMAM-Calix-Dendrimers for the Determination of Uric Acid.

A flow-through biosensor system for the determination of uric acid was developed on the platform of flow-through electrochemical cell manufactured by 3D printing from poly(lactic acid) and equipped with a modified screen-printed graphite electrode (SPE). Uricase was immobilized to the inner surface of a replaceable reactor chamber. Its working volume was reduced to 10 μL against a previously reported similar cell. SPE was modified independently of the enzyme reactor with carbon black, pillar[5]arene, poly(amidoamine) dendrimers based on the p-tert-butylthiacalix[4]arene (PAMAM-calix-dendrimers) platform and electropolymerized 3,7-bis(4-aminophenylamino) phenothiazin-5-ium chloride. Introduction of the PAMAM-calix-dendrimers into the electrode coating led to a fivefold increase in the redox currents of the electroactive polymer. It was found that higher generations of the PAMAM-calix-dendrimers led to a greater increase in the currents measured. Coatings consisted of products of the electropolymerization of the phenothiazine with implemented pillar[5]arene and PAMAM-calix-dendrimers showing high efficiency in the electrochemical reduction of hydrogen peroxide that was formed in the enzymatic oxidation of uric acid. The presence of PAMAM-calix-dendrimer G2 in the coating increased the redox signal related to the uric acid assay by more than 1.5 times. The biosensor system was successfully applied for the enzymatic determination of uric acid in chronoamperometric mode. The following optimal parameters for the chronoamperometric determination of uric acid in flow-through conditions were established: pH 8.0, flow rate 0.2 mL·min-1, 5 U of uricase per reactor. Under these conditions, the biosensor system made it possible to determine from 10 nM to 20 μM of uric acid with the limit of detection (LOD) of 4 nM. Glucose (up to 1 mM), dopamine (up to 0.5 mM), and ascorbic acid (up to 50 μM) did not affect the signal of the biosensor toward uric acid. The biosensor was tested on spiked artificial urine samples, and showed 101% recovery for tenfold diluted samples. The ease of assembly of the flow cell and the low cost of the replacement parts make for a promising future application of the biosensor system in routine clinical analyses.

Gold Nanoparticle-Modified Carbon-Fiber Microelectrodes for the Electrochemical Detection of Cd2+ via Fast-Scan Cyclic Voltammetry.

Neurotoxic heavy metals, such as Cd2+, pose a significant global health concern due to their increased environmental contamination and subsequent detrimental health hazards they pose to human beings. These metal ions can breach the blood-brain barrierblood-brain barrier, leading to severe and often irreversible damage to the central nervous system and other vital organs. Therefore, developing a highly sensitive, robust, and rapid in vivo detection method for these hazardous heavy metal ions is of the utmost importance for early detection, thus initiating timely therapeutics. Detecting ultra-low levels of toxic metal ions in vivo and obtaining accurate speciation information remains a challenge with conventional analytical techniques. In this study, we fabricated a novel carbon carbon-fiber microelectrode (CFM)-based sensor that can detect Cd2+ ions using fast-scan cyclic voltammetry by electrodepositing gold nanoparticles (AuNP). We optimized electrochemical parameters that generate a unique cyclic voltammogram (CV) of Cd2+ at a temporal resolution of 100 ms with our novel sensor. All our experiments were performed in tris buffer that mimics the artificial cerebellum fluid. We established a calibration curve resulting in a limit of detection (LOD) of 0.01 µM with a corresponding sensitivity of 418.02 nA/ µM. The sensor's selectivity was evaluated in the presence of other metal ions, and it was noteworthy to observe that the sensor retained its ability to produce the distinctive Cd2+ CV, even when the concentration of other metal ions was 200 times higher than that of Cd2+. We also found that our sensor could detect free Cd2+ ions in the presence of complexing agents. Furthermore, we analyzed the solution chemistry of each of those Cd2+-ligand solutions using a geochemical model, PHREEQC. The concentrations of free Cd2+ ions determined through our electrochemical data align well with geochemical modeling data, thus validating the response of our novel sensor. Furthermore, we reassessed our sensor's LOD in tris buffer based on the concentration of free Cd2+ ions determined through PHREEQC analysis, revealing an LOD of 0.00132 µM. We also demonstrated the capability of our sensor to detect Cd2+ ions in artificial urine samples, showcasing its potential for application in actual biological samples. To the best of our knowledge, this is the first AuNP-modified, CFM-based Cd2+ sensor capable of detecting ultra-low concentrations of free Cd2+ ions in different complex matrices, including artificial urine at a temporal resolution of 100 ms, making it an excellent analytical tool for future real-time, in vivo detection, particularly in the brain.

Development of new matrix reference materials for quantitative urine analysis in drug tests.

Accurate quantitative analyses require standardized methods to control and improve the analytical process in the laboratory. The availability of urine reference materials (RMs) may offer a feasible option to improve the accuracy of urine analysis and to control matrix effects. This paper presents the complete process of the development of matrix RMs in urine, including sample preparation, homogeneity, and stability studies, as well as uncertainty assessment. A freeze-drying process was developed, and freeze-dried human and pig urine samples were prepared and verified to have comparable homogeneity to liquid samples and higher stability than liquid human, pig, and artificial urine samples at 4℃ or room temperature and under extreme conditions. A total of 21 authentic urine samples from August 2022 were measured with freeze-dried RMs and spiked urine samples, and the reliability of the quantification of the RMs was compared. The freeze-dried human urine matrix RM appeared to be an excellent tool for daily quality control, as it showed high stability and gave the most consistent results with spiked samples.

Highly sensitive AIEE active fluorescent probe for detection of deferasirox: extensive experimental and theoretical studies.

High concentrations of deferasirox (DFX) in living organisms cause hepatic, gastric and renal malfunctions. Therefore, it is significant to establish an accurate and efficient approach for the detection of deferasirox (DFX) to protect public health. Herein, we synthesized a thiourea-based diphenylacetamide probe MPT for the effective sensing of deferasirox through the fluorescence quenching phenomenon. The designed probe MPT shows a fluorescence quenching response toward deferasirox (DFX) through photo-induced electron transfer (PET). Furthermore, DFT studies were performed to support the experimental results. 1H-NMR titration experiment was used to explore the interaction type between probe MPT and DFX. The existence of non-covalent interactions was verified with spectroscopic studies that were assisted by NCI studies, QTAIM and SAPT0 analysis. Dynamic light scattering (DLS) analysis and scanning electron microscopy (SEM) were used to investigate the complexation of probe MPT with DFX. Moreover, the on-site solution phase and solid-state detection of DFX by probe MPT are executed. Additionally, the practical applications of probe MPT to sense DFX were also revealed in human plasma as well as in artificial urine samples.

Additive-manufactured paper-PMMA hybrid microfluidic chip for simultaneous monitoring of creatinine and pH in artificial urine.

Nowadays, kidney dysfunction is a common health issue due to the modernized lifestyle. Even though medications are commercially available to treat kidney diseases, early diagnosis is crucial and challenging. Clinically, measuring urine creatinine and pH has gained significant interest as a way to diagnose kidney diseases early. In the present work, we attempted to develop a low-cost, robust, accurate and naked-eye colorimetric method to determine both creatinine levels and pH variations in artificial urine samples using a simple 3D-printed hybrid microfluidic device. Creatinine was detected by the incorporation of the traditional Jaffe test onto the hybrid paper-PMMA microfluidic device and pH (4-8) was measured by a simple anthocyanin test. Notably, the tests were established without employing any sophisticated or costly instrument clusters. The developed 3D-printed microfluidic probe showed a limit of detection (LOD) of 0.04 mM for creatinine over a concentration range of 1-10 mM, with a regression coefficient (R2) of 0.995 in laboratory conditions. Interestingly, the experimental data obtained with artificial urine exhibited a wide linear range from 0.1 mM to 5 mM under different pH values ranging from 4 to 8 in the presence of matrices commonly found in urine samples other than proteins, indicating the potential use of this method in pre-clinical analysis. Since the wide linear range of urine creatinine in artificial urine samples falls well below the clinically relevant concentrations in humans (0.07-0.27 mM), the developed lab-on-chip device is further suitable for clinical evaluation with proper ethical clearance. This 3D-printed hybrid microfluidic colorimetry-based creatinine detection and pH indicator platform can be beneficial in the healthcare sector due to the on-site testing capability, cost-effectiveness, ease of use, robustness, and instrument-free approach.

Adsorption and detection tramadol in aqueous solution by fluorescent- magnetic molecularly imprinting polymers

BackgroundThe usage of tramadol (TR) as one of the most common analgesics is expansively growing in the world. Therefore, there is an urgent requirement for a rapid and reliable method for the on-site detection of tramadol in different samples. The elimination half-life of tramadol is about 6 h, and its removal from body is relatively slow. So, it is very critical providing a method for rapid detection of tramadol. MethodsIn this study, three magnetic nanocomposites (Fe3O4, Fe3O4/SiO2, and Fe3O4/SiO2/CMC) and molecularly imprinted polymers (MIPs) based on those in the presence of graphene quantum dots (GQDs) were synthesized and investigated for selective adsorption and detection of TR in aqueous solution. For the characterization of synthesized materials, XRD, FT-IR, SEM, VSM, and the response surface method (RSM) were also employed to optimize and estimate the effective parameters of TR adsorption by these materials. Significant findingsThe results of investigating the absorption ability of nanocomposites showed that the Fe3O4/SiO2/CMC composite has higher absorption ability than the other two nanocomposites. Moreover, Fe3O4/SiO2/CMC has an excellent ability to adsorb of TR with a removal percentage of 97.46 % at pH = 7, initial TR concentration = 15 mg/L, composite dosage = 1.5 g/L, and contact time = 6 min. According to the experimental results, the imprinting factors (IF) of MIP-Fe3O4, MIP-Fe3O4/SiO2, and MIP-Fe3O4/SiO2/CMC are 1.02, 1.72, and 2.19, respectively. Therefore, the MIP-Fe3O4/SiO2/CMC was chosen as a selective sensor, and the sensitivity of its response was investigated. The detection of TR was performed by fluorescence spectroscopy at a concentration range of TR of 0 to 250 µM, and a sensitivity of 3.13 a.u./µM and limit of detection of 2.08 µM were determined. Also, the river water and artificial urine samples (with TR of 10 µM) was detected using MIP-Fe3O4/SiO2/CMC, and the results of the sensor showed a TR concentration of river water is 9.97 µM and artificial urine is 10.456 µM and which is very good and acceptable precision.