Real Urine Samples Research Articles

Simultaneous Detection of Citric Acid and Oxalic Acid Based on Dual Spectrum and Biomimetic Peroxidase for Urolithiasis Screening with a Fully Automatic Urine Analyzer.

Urolithiasis stands as a prevalent ailment within the urinary system, with hyperoxaluria and hypocitraturia being the most frequent manifestations characterized by excessive oxalic acid (OA) and deficient citric acid (CA) levels in urine. Detecting these compounds in urine quantitatively holds paramount importance for early urolithiasis screening. Existing methodologies fall short in achieving simultaneous and on-site identification of OA and CA, posing challenges for accurate urolithiasis screening. Addressing this concern, the study successfully accomplishes the concurrent identification of OA and CA in urine through a combination of dual-spectral analysis and biomimetic peroxidase utilization. Bovine serum albumin and dithiothreitol-modified copper nanoclusters (BSA-DTT-CuNCs) are employed as biomimetic peroxidases, effectively mitigating interference and enabling the simultaneous determination of OA and CA. The quantification range spans from 0 to 12mm for OA and 0.5 to 2.5mm for CA, with detection limits of 0.18 and 0.11mm, respectively. To facilitate swift and on-location urine analysis, a fully automated urine analyzer (FAUA) is introduced that streamlines the process of biomarker pretreatment and identification within urine samples. Validation with real urine samples from urolithiasis patients demonstrates the method's diagnostic precision, highlighting the dual-spectral technique and analyzer's promising role in urolithiasis screening.

Synthesis of 2D VO2 Nanosheets for the Dual Optical Sensor Method by Colorimetric and Fluorometric Sensing of Catecholamines.

For the first time, we report a dual optical sensor method (DOSM) using novel 2D VO2 nanosheets to act as fluorometric and colorimetric sensors to perform quantitative analysis of epinephrine (EP) and dopamine (DA). The wide color spectrum of the 2D vanadium oxidation series and specifically metastable blue 2D VO2 nanosheets were used to develop a DOSM biosensor. DA and EP are the major catecholamines in the human body that play vital roles as neurotransmitters and stress-responsive hormones of the endocrine system, respectively. Accurate and selective detection of these biomolecules can assist in the diagnosis of many neuroendocrine system-related diseases. The newly synthesized 2D VO2 nanosheet sensor showed bluish-green fluorescence as the first-ever fluorescence from 2D VO2 nanosheets. This sensor showed dual-function sensing toward EP by a dominant color change and fluorescence quenching. It is capable of individually detecting and quantifying both EP and DA with high selectivity and sensitivity by using both colorimetry and fluorometry simultaneously, with the detection limits of 1.07 and 5.54 μM for colorimetric analysis, respectively, and 48.07 and 3.98 μM for fluorescence analysis, respectively. The DOSM sensor was directly applied to real urine samples and gained satisfactory recovery above 90% by means of spiked concentrations. This study has opened a new platform using the DOSM and the vanadium oxidation spectrum in a much more effective way for biosensing. The fluorescence capabilities of this metal oxide can be further applied to many sensor applications based on both fluorescence and colorimetric detection.

A “signal-on” cathodic photoelectrochemical biosensor based on Cu-MOF@Cu2O heterostructure for L-cysteine detection

Cathodic photoelectrochemical (PEC) sensor has attracted extensive attention as a convenient and efficient detection method. In this study, a “signal-on” cathodic PEC sensor based on Cu-MOF modified Cu2O heterostructure (Cu-MOF@Cu2O) has been successfully constructed for L-Cysteine (L-CySH) detection. Compared with Cu-MOF and Cu2O, the photocurrent response of Cu-MOF@Cu2O heterostructure are significantly enhanced due to the improved visible light capturing ability and photoelectric conversion efficiency. For the detection of L-CySH, L-CySH can be coupled to the electrode surface via CuS bond and further oxidized by copper ions (Cu2+) to form L-Cystine (L-CySSyC). Then, the L-CySSyC serves as the electron acceptor to scavenge the photogenerated electron of Cu-MOF@Cu2O, resulting in the increase of photocurrent response. The linear concentration range for L-CySH detection is 0.5–500.0 μM, and the detection limit is 0.32 μM. Furthermore, this sensor also has been obtained satisfactory results for L-CySH detection in real urine samples.

Tablet-Based Sensor: A Stable and User-Friendly Tool for Point-of-Care Detection of Glucose in Urine.

The colorimetric detection of glucose in urine through enzymatic reactions offers a low-cost and non-invasive method to aid in diabetes management. Nonetheless, the vulnerability of enzymes to environmental conditions, particularly elevated temperatures, and their activity loss pose significant challenges for transportation and storage. In this work, we developed a stable and portable tablet sensor as a user-friendly platform for glucose monitoring. This innovative device encapsulates glucose oxidase and horseradish peroxidase enzymes with dextran, transforming them into solid tablets and ensuring enhanced stability and practicality. The enzymatic tablet-based sensor detected glucose in urine samples within 5 min, using 3,3',5,5'-tetramethylbenzidine (TMB) as the indicator. The tablet sensor exhibited responsive performance within the clinically relevant range of 0-6 mM glucose, with a limit of detection of 0.013 mM. Furthermore, the tablets detected glucose in spiked real human urine samples, without pre-processing, with high precision. Additionally, with regard to thermal stability, the enzyme tablets better maintained their activity at an elevated temperature as high as 60 °C compared to the solution-phase enzymes, demonstrating the enhanced stability of the enzymes under harsh conditions. The availability of these stable and portable tablet sensors will greatly ease the transportation and application of glucose sensors, enhancing the accessibility of glucose monitoring, particularly in resource-limited settings.

Development of a disposable hollow fibre-solid phase microextraction device using chitosan functionalised MWCNTs and a polyoxometalate for the simultaneous extraction of angiotensin II receptor blocker drugs

ABSTRACT Valsartan and Losartan are two angiotensin II receptor blocker drugs used to treat heart failure and high blood pressure. A straightforward and disposable hollow fibre-solid phase microextraction device was developed to extract these drugs from real water and urine samples. A green sorbent was synthesised by functionalised MWCNTs with chitosan through a chemical route method. Besides, a polyoxometalate (Ni-CoWO4 nanoparticles) was prepared as a modifier using the hydrothermal procedure. Using the sol-gel strategy, the sorbent and modifier were reinforced in the hollow fibre pores and lumen. The approach leads to an increase in the sorbent coating stability on/in hollow fibre. The influential factors were optimised with an experimental design, indicating that pH, extraction time, and desorption time significantly affect the Valsartan and Losartan extraction. The linearity of the method to determine Valsartan and Losartan was 3.4–1850 and 3.1–1800 ng mL−1, with R squared of 0.9929 and 0.9947, respectively. The detection and quantification limits were lower than 0.9 ng mL−1 and 3.4 ng mL−1, respectively. The pre-concentration factors for determining Valsartan and Losartan with a concentration of 20 ng mL−1 were 654.2 and 546.3, respectively. The intra-day and inter-day RSDs were lower than 3.11% and 3.87% for measuring Valsartan and Losartan. The recoveries and RSDs for analysing spiked eal water and urine samples were between 91.8–97.8% and 3.16–4.10%, respectively.

Hg2+ detection and information encryption of new [1+1] lanthanide cluster

The sensing of heavy metal ion and information encryption are two very important research areas. Therefore, developing multi-functional materials capable of sensing heavy metal ions and encrypting information is highly important. In this work, three [1 + 1] lanthanide clusters [Ln(TFBA)3(dmp) (H2O)2]2 (Ln = Tb3+Tb1+1, Eu3+Eu1+1, Gd3+Gd1+1, HTFBA = 2,3,4,5-tetrafluorobenzoic acid, dmp = 4,7-dimethyl-1,10-phenanthroline) were designed and synthesized. Among them, Tb1+1 shows excellent luminescence sensing towards Hg2+ (Ex = 350 nm, Em = 545 nm). Results demonstrates the sensing with high selectivity, strong anti-interference, 20-s response time, high accuracy, excellent linear relationship in 0–20.0 μM, and a very low limit of detection (0.02 ppb). Furthermore, paper strips based on Tb1+1 is fabricated for visual detection of Hg2+ in real samples of tap water, lake water, human urine, and human serum. More interestingly, a new method for confidentiality of information is realized through multi-color anti-counterfeiting patterns with the [1 + 1] lanthanide cluster ink, based on the luminescence “on-off” sensing towards Hg2+.

High sensitivity, low-cost, and disposability: A novel screen-printed electrode developed for direct electrochemical detection of the antibiotic ceftriaxone

This study describes the development of a novel disposable and low-cost electrochemical platform for detecting the antibiotic ceftriaxone. The screen-printed electrode has been modified with a novel hybrid nanostructure containing silicon oxide (SiO2), zirconium oxide (ZrO2), and nitrogen-doped carbon quantum dots (Cdot-N). Different techniques like Fourier-transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy characterized the hybrid nanostructure used in the sensor surface modifier material. The hybrid nanostructure showed an excellent synergistic effect that contributed to the oxidation reaction of ceftriaxone. The screen-printed electrode modified with SiO2/ZrO2/Cdot-N nanostructure presented high sensitivity with a detection limit of 0.2 nmol L−1 in the linear range of 0.0078–40.02 μmol L−1. The measurements have been performed by square wave voltammetry technique. Studies on real samples of synthetic urine, urine, and tap water showed 95%–105% recovery without applying any sample pretreatment. The sensor demonstrated excellent selectivity in the antibiotic ceftriaxone determination in the presence of possible interferences cationic, Na+, K+, Ca2+, Mg2+, Cu2+, Pb2+, Mn2+, Zn2+, Co2+, and biological, glucose, caffeine, uric acid, and ascorbic acid. The developed sensor becomes a selective, sensitive, and applicable tool in determining the antibiotic ceftriaxone.

Electrochemical Sensing Platform Based on Metal Nanoparticles for Epinephrine and Serotonin.

A sensing platform based on nanocomposite materials composed of gold metal nanoparticles (AuNPs) and conducting polymer (CP) matrix has been developed for serotonin and epinephrine detection. The CP-AuNPs nanocomposite materials have been synthesized onto glassy carbon electrodes (GCE) by using novel electrochemical procedures based on sinusoidal currents (SC). The SC procedures ensured good control of the metal nanoparticles distribution, increased electrochemical surface area, and enhanced analytical performance. The proposed sensing platform displayed good analytical performance toward serotonin and epinephrine detection. A wide linear analytical response toward epinephrine in the range from 10 to 640 μM and a low detection limit of 1.4 μM epinephrine has been obtained. The sensing platform has also displayed a linear response toward serotonin in the range from 10 to 320 μM, with a detection limit of 5.7 μM serotonin. The sensing platform has been successfully applied in the analysis of epinephrine and serotonin in real samples of tap water and urine with good accuracy.

In-situ synthesis of novel multifunctionally linked tin oxide on holy reduced graphene oxide: An electrocatalyst for antipsychotic drug sensing

Herein, we developed a novel electro-catalyst containing multifunctionally linked tin oxide on holy reduced graphene oxide (mf-SnO2/h-rGO) was prepared through a facile in situ hydrothermal method. The mf-SnO2/h-rGO coated onto the screen-printed carbon electrode (SPCE), which is used as a working electrode for the highly sensitive detection of phenothiazine (PTZ). The mf-SnO2/h-rGO/SPCE working electrode has an electroactive surface area of 0.66 cm2, peak to peak separation (∆Ep) of 122 mV, the ratio of anodic (Ipa) and cathodic (Ipc) current is 0.98, and charge transfer resistance (Rct) of 0.24 kΩ. The prepared mf-SnO2/h-rGO catalyst shows a good detection limit (LOD) of 0.168 10−9 mole/L (Epa = 0.04 V) and 0.035 10−9 mole/L (Epa = 0.33 V) and an outstanding sensitivity of 1.44 μA/mM cm2. The proposed sensor exhibits an acceptable stability, selectivity, repeatability and reproducibility. For real sample analysis, blood serum and urine samples were performed and mf-SnO2/h-rGO shows good recovery.

Getting rid of reference electrode in potentiometric multisensor measurements

Reference electrodes are indispensable part of electroanalytical methods; however, their use may often limit the options for miniaturization of the measurement set-up which is an important requirement for handling small sample volumes in biomedical studies. This is also true for potentiometric multisensor systems (“electronic tongues”) that are currently being rapidly developed for numerous analytical applications. We describe an approach to potentiometric multisensor measurements allowing the elimination of reference electrode from the measurement scheme. The idea is based on the employment of “cross-voltages” – the potentials of the sensors measured against each particular sensor of multisensor array with subsequent chemometric processing of these data. In this scenario each sensor in turn becomes a pseudo-reference electrode, thus the overall measuring protocol is as simple as direct potentiometry with only difference at the data treatment stage, where chemometric processing is required to extract the analytical information. The feasibility of this scheme is demonstrated for analysis of several model mixtures and for real urine samples. The accuracy attained by this procedure is at least the same as in classical multisensor measurements scheme and in several cases the cross-voltage approach yielded two times better accuracy, thus proving the perspective of the proposed measuring protocol.

Hydrothermal synthesis of cobalt germanium oxide supported with carbon-based graphitic carbon nitride for electrochemical determination of ornidazole

In recent decades, nitroimidazole derivatives have played an effectual role against bacterial and protozoan infections that can be used as anti-cancer and antibiotic drugs. Ornidazole (ORD) consists of a major 5-imidazole nucleus which complements to first nitro groups, ORD invades into lipid tissue and other nitroimidazole derivatives. The periodic intake of ORD orally causes side effects of headache, nausea, vomiting, and breathing difficulties such effects need potential monitoring and develop essential electrochemical sensing toward ORD. In this study, we developed a ternary cobalt germanium oxide (Co2GeO4) nanoparticle prepared by a facile hydrothermal method and followed by calcination. The carbon-based graphitic carbon nitride (GCN, g-C3N4) nanosheets were therefore supported for electrochemical sensing applications in order to improve the features like the catalytic activity, electrical conductivity, and active surface area of Co2GeO4 composites. The structural, chemical composition, and morphological properties of samples were characterized. Subsequently, the fabrication of cobalt germanium oxide with graphitic carbon nitride (Co2GeO4/GCN) was modified over a screen-printed carbon electrode (SPCE) towards electrochemical detection of ORD. Electrochemical measurements were recorded by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) for the determination of ORD. The Co2GeO4/GCN nanocomposite exhibits a wide linear range response of 0.049–94.9 μM in DPV with a nanomolar limit of detection of 7.2 nM of ORD and a high sensitivity of 2.66 µA µM−1 cm−2. An interference study was carried out for the Co2GeO4/GCN nanocomposite in the existence of hazardous metals, biological compounds, and similar drugs for examining the selectivity of the sensor. The proposed Co2GeO4/GCN nanocomposite reveals superior sensing selectivity towards ORD; hence, repeatability, reproducibility, and storage stability were recorded in their RSD and found to be less than 0.4%, adding to this practical feasibility of the sensor analyzed by real samples of blood serum & human urine with exceptional recovery percentages.

Determination of 1,3-Diphenylguanidine, 1,3-Di-o-tolylguanidine, and 1,2,3-Triphenylguanidine in Human Urine Using Liquid Chromatography-Tandem Mass Spectrometry.

1,3-Diphenylguanidine (DPG), 1,3-di-o-tolylguanidine (DTG), and 1,2,3-triphenylguanidine (TPG) are rubber additives widely present in the indoor environment. Nevertheless, little is known about their human exposure. We developed a method for the quantification of DPG, DTG, and TPG in human urine, using high-performance liquid chromatography-tandem mass spectrometry. The quantitative analysis of target analytes at parts-per-trillion levels in urine was optimized using hydrophilic-lipophilic balanced solid-phase extraction and isotopic dilution. The method limits of detection and quantification were in the range of 0.002-0.02 and 0.005-0.05 ng/mL, respectively. The recoveries of all analytes in human urine fortified at 1, 5, 10, and 20 ng/mL concentrations were in the range of 75.3-111%, with standard deviations of 0.7-4%. The repeated measurement of similarly fortified human urine yielded intra-day and inter-day variations of 0.47-3.90 and 0.66-3.76%, respectively. The validated method was applied in the measurement of DPG, DTG, and TPG in real human urine samples, which revealed the occurrence of DPG in children's urine samples (n = 15) with a detection frequency of 73% and at a median concentration of 0.05 ng/mL. DPG was found in 20% of adults' urine samples (n = 20).

A Schiff base fluorescence switch-on probe derived from vitamin B6 cofactor for simultaneous detection of bovine serum albumin and ovalbumin

The abnormal amount of albumin found in serum and urine samples is an important biomarker for a variety of illnesses. It is essential for clinical diagnosis, medicinal research, and preventative medicine to correctly assess the albumin concentration in actual biological samples. Herein, vitamin B6 cofactors derived Schiff bases obtained by condensing pyridoxal 5′-phosphate (PLP) with 2-aminophenol (L), pyridoxal with 2-aminophenol (L1) and PLP with aniline (L2) were employed for the detection of albumins. Schiff base L is non-fluorescent due to conformational flexibility and free intramolecular rotation, but becomes fluorescent upon protein–ligand complex formation with bovine serum albumin (BSA) and ovalbumin (OVA). Other Schiff bases L1 and L2 failed to response the presence of BSA and OVA. The intensity of fluorescence of L increases linearly with the increasing concentration of BSA and OVA, and the detection limits for BSA and OVA were estimated to be 0.18 µM and 0.13 µM, respectively. The molecular docking and molecular dynamics simulations were done to investigate the binding affinity and modes between the albumins (BSA and OVA) and L. The developed detection method was applied for the detection of BSA and OVA in real biological samples of milk, serum, egg white and urine, with satisfactory recovery.

Amplification of SERS Signal of Methotrexate Using Beta-Cyclodextrin Modified Silver Nanoparticles

The paper describes the use of native β-cyclodextrin (CD) for the modification of silver nanoparticles (AgNPs) in order to improve the determination of the anticancer drug methotrexate (MTX) using surface-enhanced Raman spectroscopy (SERS). A control experiment with unmodified AgNPs showed that the strong SERS signal of MTX can only be achieved in alkaline media. However, competitive interactions and the strong background signal of human body fluid components significantly challenge MTX determination in real samples. While previous reports propose the use of thorough sample pretreatment (e.g., solid phase extraction), the application of CD-modified AgNPs increases the SERS signal of MTX in neutral media by seven times which enables simplifying the analysis and improving its accuracy by reducing the influence of endogenous components of body fluids. A detailed study of the synthesis conditions (CD concentration and reaction time) and SERS registration conditions (pH, NaCl concentration, dilution of urine samples) was performed to maximize the analytical signal and signal-to-noise ratio. The final assay was tested for MTX determination in artificially spiked samples of real human urine. The results demonstrated that MTX can be determined within the concentration range suitable for therapeutic drug monitoring (20–300 μg mL−1) with satisfactory precision (6–15% RSD), accuracy (95–111% apparent recovery), and limit of detection (0.3 μg mL−1).

Large-scale fabrication of ion-selective electrodes for simultaneous detection of Na+, K+, and Ca2+ in biofluids using a smartphone-based potentiometric sensing platform.

A significant bottleneck exists for mass-production of ion-selective electrodes despite recent developments in manufacturing technologies. Here, we present a fully-automated system for large-scale production of ISEs. Three materials, including polyvinyl chloride, polyethylene terephthalate and polyimide, were used as substrates for fabricating ion-selective electrodes (ISEs) using stencil printing, screen-printing and laser engraving, respectively. We compared sensitivities of the ISEs to determine the best material for thefabrication process of the ISEs. The electrode surfaces were modified with various carbon nanomaterials including multi-walled carbon nanotubes, graphene, carbon black, and their mixed suspensions as the intermediate layer to enhance sensitivities of the electrodes. An automated 3D-printed robot was used for the drop-cast procedure during ISE fabrication to eliminate manual steps. The sensor array was optimized, and the detection limits were 10-5M, 10-5M and 10-4M for detection of K+, Na+ and Ca2+ ions, respectively. The sensor array integrated with aportable wireless potentiometer was used to detect K+, Na+ and Ca2+ in real urine and simulated sweat samples and results obtained werein agreement with ICP-OES with good recoveries. The developed sensing platform offers low-cost detection of electrolytes for point-of-care applications.

Ultrastable Gold–Copper Nanoclusters on Nitrogen-Doped Graphene Quantum Dots for Selective Electrochemical and Fluorescence Sensing of Glycine

In this work, we present an ultrastable gold–copper nanocluster on nitrogen-doped graphene quantum dot (AuCuNC@N-GQD), with a stability of ≥1 year, achieved through a galvanic exchange process, which displayed intense solid- and solution-state near-infrared emission. Furthermore, the NC exhibited selective and dual sensing of glycine (GLY) through (nonenzymatic) electrochemical (EC) and fluorescence methods, which is assigned to the unique combination of the strong emission and conducting properties of Au–CuNC and N-GQD, respectively, in the same material and is a first-time report of all the above-mentioned. The limits of detection (LODs) obtained for GLY by EC and fluorescence sensing were 10 nM and 1 μM, respectively and are the lowest LOD values reported hitherto in the respective categories. Compared to the controls, AuCuNC@N-GQDs exhibited a ∼20-fold enhancement with a sensitivity of 0.377 μA μM–1 cm–2. The preferential Au–GLY interaction is considered to be the reason for the selective sensing of GLY by AuCuNC@N-GQD and the improvement in the electronic and conductivity characteristics due to N-GQD to the enhanced sensitivity. The sensing performance was successfully extended to real blood and urine samples spiked with GLY without interference.

Glutamic acid-capped iron oxide quantum dots as fluorescent nanoprobe for tetracycline in urine.

Thefabrication of iron oxide quantum dots (IO-QDs) modified with glutamic acid (Glu) under controllable conditionsis reported. The IO-QDs have been characterized by transmission electron microscopy, spectrofluorometry, powder X-ray diffraction, vibrating sample magnetometry, UV-Vis spectroscopy, X-ray photoelectron spectroscopy,and Fourier-transform infrared spectroscopy. The IO-QDs exhibited good stability towards irradiation, temperature elevations, and ionic strength, and the quantum yield (QY) of IO-QDs was calculated to be 11.91 ± 0.09%. The IO-QDs were furtherly measured at an excitation wavelength of 330nm with emission maxima at 402nm, which were employed to detect tetracycline (TCy) antibiotics, including tetracycline (TCy), chlortetracycline (CTCy), demeclocycline (DmCy), and oxytetracycline (OTCy) in biological samples. The results indicated that TCy, CTCy, DmCy, and OTCy in urine samples show a dynamic workingrange between 0.01 and 80.0μM; 0.01 and 1.0μM; 0.01 and 10μM; and 0.04 and 1.0μM, respectively, with detection limits of 7.69nM, 120.23nM, 18.20nM, and 67.74nM, respectively. The detection was not interfered with by the auto-fluorescence from the matrices. In addition, the obtained recovery in real urine samples suggested that the developed method could be used in practical applications. Therefore, the current study has prospect to developan easy, fast, eco-friendly, and efficient new sensing method for detecting tetracycline antibiotics in biological samples.

Magnetic layered double hydroxides for the sensitive dispersive solid phase microextraction of hippuric acid in urine samples prior to HPLC-UV analysis

The core- shell structural layered double hydroxide (Fe3O4-SiO2-EN@Zn-Al-LDH) was successfully synthesized and applied as a solid sorbent in the magnetic dispersive micro solid-phase-extraction (M-DµSPE) method. It was combined with high-performance liquid chromatography for the trace analysis of hippuric acid (HA) from urine samples. The obtained magnetic layered double hydroxides (LDHs) were characterized by XRD, FT-IR, VSM, FE-SEM, and BET techniques. The characterization analysis indicated that Fe3O4- SiO2- EN@ Zn-Al-LDH has a sufficient surface area and good saturation magnetism. The affecting variables on the extraction of HA by the proposed method were optimized. Excellent adsorption capacity (127.8 mg g−1), wide linearity dynamic range (0.015–500 µg mL−1), and satisfactory limits of detection and quantification (0.055 and 0.014 µg mL−1, respectively) could be obtained under optimum conditions. The good repeatability and low relative standard deviation (7.2 %), low carry-over (2.7%), good matrix effect (93.6%), high reusability (up to 19 times), and an acceptable percent recovery value (97.2%) proved the selectivity and applicability of the proposed method for the extraction of the trace levels of HA in real urine samples.

Nitazoxanide and azithromycin for the early treatment of COVID‐19: A multi‐spectroscopic, biochemical and computational drug–drug interaction study

AbstractHerein, we present an experimental and theoretical drug–drug interaction study between nitazoxanide (NTZ) and azithromycin (AZT) in an aqueous solution. Interaction was studied by using UV/Vis, fluorescence, attenuated total reflectance‐fourier transform infrared (ATR‐FTIR), and circular dichroism (CD) spectroscopy, while molecular docking studies were performed to establish the interaction computationally. A bright yellow color was observed when the two drugs interacted, giving a hyperchromic band at 420 nm. The rate of absorbance was linearly increased by increasing drug concentrations and in a time‐dependent manner. Stability of the interaction complex (i.e., NTZ: AZT) was measured at variable temperatures (25–80°C), pH (5.0–10.0) and ionic strength (0.05–2.0 M NaCl), and not only proved stable but also retained antimicrobial potential with reduced cellular toxicity. Mole ratio and Job's method of continuous variations were used to establish the binding stoichiometry and found to be 2:1. The calculated binding constant (kb = 8,400 M−1) and Gibb's free energy (ΔG° = −22.4 KJ/mol) also suggested an energetically favorable interaction. FTIR spectra of NTZ: AZT complex in comparison with two drugs alone revealed significant interaction which was nicely complemented by molecular docking studies. Interaction was also successfully demonstrated in presence of carrier protein HSA and by spiking the two drugs in real samples of human plasma and urine.

Magnetic Solid-Phase Microextraction Protocol Based on Didodecyldimethylammonium Bromide-Functionalized Nanoparticles for the Quantification of Epirubicin in Biological Matrices.

Due to epirubicin's (EPI) narrow therapeutic index and risk of cardiotoxicity, it is critical to monitor concentrations of this drug when being used to treat cancer patients. In this study, a simple and fast magnetic solid-phase microextraction (MSPME) protocol for the determination of EPI in plasma and urine samples is developed and tested. Experiments were performed using prepared Fe3O4-based nanoparticles coated with silica and a double-chain surfactant-namely, didodecyldimethylammonium bromide (DDAB)-as a magnetic sorbent. All the prepared samples were analyzed via liquid chromatography coupled with fluorescence detection (LC-FL). The validation parameters indicated good linearity in the range of 0.001-1 µg/mL with a correlation coefficient > 0.9996 for plasma samples, and in the range of 0.001-10 µg/mL with a correlation coefficient > 0.9997 for urine samples. The limit of detection (LOD) and limit of quantification (LOQ) for both matrices were estimated at 0.0005 µg/mL and 0.001 µg/mL, respectively. The analyte recovery after sample pretreatment was 80 ± 5% for the plasma samples and 90 ± 3% for the urine samples. The developed method's applicability for monitoring EPI concentrations was evaluated by employing it to analyze real plasma and urine samples collected from a pediatric cancer patient. The obtained results confirmed the proposed MSPME-based method's usefulness, and enabled the determination of the EPI concentration-time profile in the studied patient. The miniaturization of the sampling procedure, along with the significant reduction in pre-treatment steps, make the proposed protocol a promising alternative to routine approaches to monitoring EPI levels in clinical laboratories.