Real Urine Research Articles

A highly stable copper nano cluster on nitrogen-doped graphene quantum dots for the simultaneous electrochemical sensing of dopamine, serotonin, and nicotine: a possible addiction scrutinizing strategy.

A highly stable copper (Cu) nanocluster (NC), which exhibited stability for more than one year, was synthesized using nitrogen-doped graphene quantum dots (N-GQDs) as reducing and capping agents and smaller glutathione molecules as additional capping agents. The synthesized NC, CuNC@N-GQDs, successfully sensed dopamine (DA), serotonin (SER), and nicotine (NIC) simultaneously with well-defined peaks and good peak-to-peak separation, whereas none of the controls including CuNCs and N-GQDs exhibited the simultaneous sensing properties. In addition, they exhibited enhanced sensitivity with current responses ∼4, ∼4, and ∼2 times those of the corresponding control for DA, SER, and NIC. The limits of detection obtained were 0.001, 1.00, and 0.01 nM for DA, SER, and NIC, respectively. The higher sensitivity and the simultaneous sensing are indicative of the synergistic effect of CuNCs and N-GQDs in the CuNC@N-GQDs. The sensing performance was successfully extended to real blood and urine samples spiked with DA, SER, and NIC.

Self-assembled nanoplatforms with ZIF-8 as a framework for FRET-based glutathione sensing in biological samples.

A glutathione (GSH) optical sensor with high sensitivity and exceptional selectivity was established for the first time. Zeolitic imidazolate framework-8 (ZIF-8) as a model was used for the first time to entrap Mn2+:ZnS quantum dots (QDs) and a rhodamine B derivative (RBD) by self-assembly. Benefiting from the confinement effect of ZIF-8, the loaded QDs and RBD can be brought into close proximity for energy transfer to occur. In the presence of GSH, the fluorescence resonance energy transfer (FRET) process from the QDs to RBD can be initiated, rendering the fluorescent nanoprobe to exhibit a response to GSH. The fluorescence intensity of Mn2+:ZnS@ZIF-8@RBD decreased with an increase in the GSH concentration in the linear range of 5-120 μM and a detection limit of 1.5 μM. This finding leads to a method for the fluorescence detection of GSH with excellent selectivity over other reactive thiols. Moreover, because of its good accuracy and excellent recovery, the nanoplatform can be applied for GSH sensing in real human serum and urine samples. Hence, the developing probe may be extended to other optical sensing domains or drug carriers and has tremendous potential in the field of biomedicine.

Elaboration of a novel nanosensor using nanoparticles of α-Fe2O3 magnetic cores for the detection of metronidazole drug. Urine human and tap water

Metronidazole (MTZ) is a widely used antibiotic to treat infections caused by anaerobic bacteria, protozoa, and bacteroids such as trichromonosis and vaginosis. In this study, we present a simple strategy for constructing an electroanalysis platform for metronidazole in real samples. We prepared a modified carbon paste with α-Fe2O3 magnetic core nanoparticles to construct an α-Fe2O3@CPE electrochemical sensor. The surface morphology and composition of the sensor were evaluated using several methods, such as X-ray diffraction and scanning electron microscope. The average size of the α-Fe2O3 magnetic core nanoparticles was around 34.30 ​nm. Cyclic voltammetry, electrochemical impedance spectroscopy and chrono-coulometry were performed for the understanding of the electron transfer behavior on the electrocatalytic surface of α-Fe2O3@CPE and the unmodified electrode CPE. The resulting sensor demonstrates a very good shift of the Metronidazole reduction peak to a more positive potential (−0.57v vs Ag/AgCl) compared to the unmodified CPE electrode (−0.71v .vs Ag/AgCl). The Metronidazole peak reduction current Ipc varies linearly with metronidazole concentration in the range of 10-4 ​M to 0.8x10-6 ​M with a limit of detection and limit of quantification of 2.852x10-7 ​M and 9.509x10-7 ​M respectively. Exceeding the detection limits of several existing analytical methods. The proposed procedure has been successfully demonstrated on pharmaceutical tablets and real tap water and urine samples.

Tyndall-effect-based colorimetric assay with colloidal silver nanoparticles for quantitative point-of-care detection of creatinine using a laser pointer pen and a smartphone.

Herein, this paper initially reports a new colorimetric Tyndall effect-inspired assay (TEA) for simple, low-cost, sensitive, specific, and point-of-care detection of creatinine (an important small biomolecule) by making use of silver nanoparticles (AgNPs) as model colloidal nanoprobes for visual light scattering signaling. The naked-eye TEA method adopts negatively-charged citrate-capped AgNPs (Cit-AgNPs) prepared by sodium citrate reduction. In the presence of alkaline conditions, the creatinine analyte can form carbanion/oxoanion amino tautomers which in turn crosslink with carboxylate groups on the Cit-AgNPs via a hydrogen bonding network to mediate the aggregation of such colloidal nanoprobes showing a significantly-enhanced TE signal that was created and quantified by a hand-held laser pointer pen and a smartphone, respectively. The results demonstrate that the resulting equipment-free method with the TE readout could enable the portable quantification of creatinine with a detection limit of ∼55 nM, which was ∼90–2334 times lower than that obtained from AgNP-based colorimetric approaches with the most common localized surface plasma resonance signaling. Moreover, it shows a larger analytical sensitivity up to ∼580.8227 signal per nM, offering ∼2.4–232-fold improvement in comparison with many of the recent instrumental creatinine nanosensors. The accuracy and practicality of the developed nanosensing system was additionally confirmed with satisfactory recovery results ranging from ca. 98.52 to 100.36% when analyzing a set of real complex human urine samples.

Estimation of Some Useful Drugs in Water, Urine, and Medical Formulations Following Conventional and Modified Dispersive Microextraction Coupled with HPLC-UV

Dispersive Liquid-Liquid Microextraction (DLLME) coupled with high-performance liquid chromatography-ultraviolet spectroscopy was developed, as a fast and precise operation, for extractive recovery and estimation of two pharmaceuticals viz. moxifloxacin and galantamine, from water, urine, and medical formulations. The process was investigated for Extraction (ES) and Dispersive Solvent (DS) as well as pH, temperature, and salt concentration. Extraction was found effective using methanol (CH3OH), as the DS, employing 1,1,2,2-tetrachloroethane (C2H2Cl4) and chloroform (CHCl3), as the ES, for moxifloxacin and galantamine respectively. The optimum pH was found to be 6.9 for moxifloxacin and 10.2 for galantamine. Temperature and salt were found to have some influence on the extraction efficiency of moxifloxacin but insignificant for galantamine. An improvement of the operation in terms of the Extraction efficiency (ER %), Preconcentration Factor (PF), thermodynamic feasibility, and greenness were achieved during surfactant aided DLLME (SDS-DLLME), where anionic surfactant (Sodium Dodecyl Sulphate (SDS)) was employed and no DS was required. Interestingly, the volume requirement for ES was found less, compared to that in the conventional DLLME, without compromising the performance. Moreover, quantitative recovery of both the drugs was achieved using a single ES. Thus, mutual separation and simultaneous determination of moxifloxacin and galantamine may be designed. A two-phase separation with concomitant enrichment of the solute in the sediment phase occurred. The drugs in the sediment phase, on subsequent dilution with methanol, were determined using the High Performance Liquid Chromatography-Ultraviolet (HPLC-UV) system. The negative free energy changes for the operation indicated that the process was thermodynamically feasible. The process was found to be effective for the spiked recovery of the studied drugs from real samples viz, water, human urine, and commercial medical formulations.

A versatile sensing platform based on FeOOH nanorod/expanded graphite for electrochemical quantification of bioanalytes

Quantitative analysis of biologically important compounds plays extraordinary roles in diagnostic studies of human health. In this study, a versatile electrochemical sensing platform is proposed for selective quantification of ascorbic acid (AA), dopamine (DA), uric acid (UA), acetaminophen (AC) and l-tryptophan (Trp). Such a platform is based on a nanocomposite of FeOOH nanorod and expanded graphite (FeOOH nanorod/EG), prepared through a hydrothermal process. The characterization of its morphology and electrochemical properties by means of microscopic methods and electrochemical techniques reveals that this nanocomposite exhibits outstanding electrocatalytic activity and sensing performance toward these bioanalytes. A combined action between EG and FeOOH is confirmed, where the former provides a huge electroactive surface area as well as a fast electron transfer rate, while the latter features strong electrical catalytic ability. This platform exhibits high sensitivity toward voltammetric quantitation of AA, DA, UA, AC and Trp, and their detection limits are 3.28, 0.22, 0.02, 0.0014 and 0.03 μM (S/N = 3), respectively. Beyond that, the proposed FeOOH nanorod/EG electrochemical sensing platform shows good selectivity, high reproducibility and stability in the quantitative analysis of these bioanalytes. The established sensing platform has been also successfully adopted in analyzing these bioanalytes in real biological serum and urine samples or commercial drugs. Consequently, the fabricated FeOOH nanorod/EG nanocomposite is a promising electrode material in the applications of sensing different bioanalytes.

Determination of three urinary catecholamines and serotonin by on-line packed-fiber solid-phase extraction

生物单胺包括儿茶酚胺类以及5-羟色胺等,在中枢神经系统中扮演着非常关键的角色,也是临床上诊断神经内分泌肿瘤疾病的重要生物标志物。由于这类单胺类物质的强化学极性导致传统吸附材料对其吸附效果不佳,从复杂生物样本中同时检测更多的生物单胺存在挑战性。该文建立了一种基于聚冠醚纳米纤维在线固相萃取检测尿液中3种儿茶酚胺(多巴胺、肾上腺素、去甲肾上腺素)和5-羟色胺的方法。采用静电纺丝法制备聚二苯并-18-冠-6醚-聚苯乙烯复合纳米纤维(PCE-PS),制成装填纤维的固相萃取(PFSPE)柱,再将PFSPE柱与HPLC进行在线联用。该在线PFSPE-HPLC方法采用双三元泵进行样品富集净化和分析,左泵连接PFSPE柱,进行样品富集净化;右泵连接分析柱进行样品分离检测。控制切换阀的切换,实现样品富集后洗脱至分析柱中分离检测。结果表明,在线PFSPE-HPLC检测尿液儿茶酚胺(多巴胺、肾上腺素、去甲肾上腺素)和5-羟色胺在1~200 ng/mL范围内有良好的线性关系,线性相关系数达0.996以上。3种儿茶酚胺和5-羟色胺的检出限(S/N=3)分别为1和2.5 ng/mL,定量限(S/N=10)分别为2.5和5 ng/mL。空白尿液和实际尿液加标回收率在83.5%~117.7%之间,日内精密度<10%。PCE-PS复合纳米纤维在多次使用后无明显变化,具有良好的稳定性,可重复使用达95次以上。在线PFSPE-HPLC方法能够集样品在线前处理与分析检测于一体,省时省力,实现分析过程的高度自动化。该方法成功应用于尿液中3种儿茶酚胺和5-羟色胺的检测,可以为临床上相关疾病检测诊断和研究提供有力的技术支持。

Modulating donor of dicyanoisophorone-based fluorophores to detect human serum albumin with NIR fluorescence

It is urgently needed to develop NIR-fluorescent probe for detection of human serum albumin (HSA) since the interference of short-wavelength-fluorescence from endogenous species in real serum and urine. However, most previous reports were located in the short-wavelength region (<600 nm). In this work, a series of dicyanoisophorone (DCO)-based fluorophores 1–4 with different donor groups have been designed and investigated. A systematic study of their photophysical properties has been carried out. Among these probes, 4 exhibited NIR emission with the highest fluorescence brightness and the most sensitive signal response to HSA. Further studies demonstrated that 4 could strongly bind into the DS1 pocket of HSA with a 1:1 ratio. Importantly, the method based on 4 has been proven to be capable of sensing HSA in real serum and urine samples.

Superior selectivity of high-frequency ultrasound toward chorine containing-pharmaceuticals elimination in urine: A comparative study with other oxidation processes through the elucidation of the degradation pathways

This work considered the sonochemical degradation (using a bath-type reactor, at 375 kHz and 106.3 W L-1, 250 mL of sample) of three representative halogenated pharmaceuticals (cloxacillin, diclofenac, and losartan) in urine matrices. The action route of the process was initially established. Then, the selectivity of the sonochemical system, to degrade the target pharmaceuticals in simulated fresh urine was compared with electrochemical oxidation (using a BDD anode, at 1.88 mA cm−2), and UVC/H2O2 (at 60 W of light and 500 mol L-1 of H2O2). Also, the treatment of cloxacillin in an actual urine sample by ultrasound and UVC/H2O2 was evaluated. More than 90% of the target compounds concentration, in the simulated matrix, was removed after 60 min of sonication. However, the sono-treatment of cloxacillin in the real sample was less efficient than in the synthetic urine. The ultrasonic process achieved 43% of degradation after 90 min of treatment in the actual matrix. In the sonochemical system, hydroxyl radicals in the interfacial zone were the main degrading agents. Meanwhile, in the electrochemical process, electrogenerated HOCl was responsible for the elimination of pharmaceuticals. In turn, in UVC/H2O2 both direct photolysis and hydroxyl radicals degraded the target pollutants. Interestingly, the degradation by ultrasound of the pharmaceuticals in synthetic fresh urine was very close to the observed in distilled water. Indeed, the sonodegradation had a higher selectivity than the other two processes. Despite the sono-treatment of cloxacillin was affected by the actual matrix components, this contrasts with the UVC/H2O2, which was completely inhibited in the real urine. The sonochemical process led to 100% of antimicrobial activity (AA) elimination after 75 min sonication in the synthetic urine, and ∼ 20% of AA was diminished after 90 min of treatment in the real matrix. The AA decreasing was linked to the transformations of the penicillin nucleus on cloxacillin, the region most prone to electrophilic attacks by radicals according to a density theory functional analysis. Finally, predictions of biological activity confirmed that the sono-treatment decreased the activity associated with cloxacillin, diclofenac, and losartan, highlighting the positive environmental impact of degradation of chlorinated pharmaceuticals in urine.

Tyndall-Effect-inspired assay with gold nanoparticles for the colorimetric discrimination and quantification of mercury ions and glutathione

This work initially reports a new nanosening method for simple, sensitive, specific, visual detection of mercury (II) (Hg2+) and glutathione (GSH) using the Tyndall Effect (TE) of the same colloidal gold nanoparticle (GNP) probes for efficient colorimetric signaling amplification. For the TE-inspired assay (TEA) method, arginine (Arg) molecules are pre-modified on the GNPs' surfaces (Arg-GNPs). Upon the Hg2+ introduction, it can be specifically coordinated with the terminal –NH2 and –COOH groups of the Arg molecules to make the Arg-GNPs aggregate, producing a significantly-enhanced TE signal in the reaction solution after its irradiation by a 635-nm red laser pointer pen. On the other hand, the introduction of the GSH results in the production of the original Arg-GNPs’ weak TE response, as it is able to bind such metal ion via mercury-thiol reactions to inhibit the above aggregation. Under the optimal conditions, the utility of the new TEA method is well demonstrated to quantitatively detect the Hg2+ and GSH with the aid of a smartphone as a portable TE reader during the linear concentration ranges of 50–3000 and 10–3000 nM, respectively. The detection limits for the Hg2+ and GSH are estimated to be as low as ∼3.5 and ∼0.3 nM, respectively. The recovery results obtained from the detection of Hg2+ in the complex tap and pond water samples and the assay of GSH in real human serum and urine samples are also satisfactory.

Fertiliser recovery from source-separated urine via membrane bioreactor and heat localized solar evaporation

Urine with its abundant macronutrients (N-P-K) is an ideal resource for the production of fertiliser. However, the odor and pathogens in the raw urine must be removed to meet the public acceptance of urine collection systems and to enable its safe reuse as a fertiliser. In this work, real urine was collected and treated through a pilot-scale gravity-driven membrane bioreactor (GDMBR) to remove the malodorous organics and to nitrify almost 50% of the ammonia into nitrate. The stablised urine was subsequently distilled via low-cost heat localized solar evaporation (HLSE) to produce a non-odorous solid fertiliser. The developed HLSE with a small footprint can attract bulk solution into a vertical insulated space and quickly heat it up to 68 °C within 1 h. The HLSE process had vapour flux at 1.3 kg m−2 h−1 as well as high solar to vapour conversion efficiency at 87%. Based on the EDX mapping and XRD analysis, the generated crystals are mainly NaNO3, NH4Cl, NaCl, NH4H2PO4 and K2HPO4, which are ideal nutrients for vegetation. In this study, the produced urine-derived fertilisers have a better performance on the growth of the leafy basil than the all-purpose commercial fertilisers. Generally, the GDMBR-HLSE is a promising cost-effective and green technology for nutrients recovery from urine.

Exploiting the capsule phase microextraction features in bioanalysis: Extraction of ibuprofen from urine samples

Undoubtedly, the exploration of new sample preparation techniques is in the forefront of research in bioanalysis. Capsule phase microextraction (CPME) is a recently introduced extraction technique based on the sol–gel sorbents which are incorporated into a porous tubular polymeric membrane. Herein, we exploited the advantageous features of CPME in biological matrices by utilizing sol–gel poly(tetrahydrofuran) (sol–gel PTHF) sorbent in CPME device for the extraction of ibuprofen (model compound) from urine samples. In CPME, both filtration and stirring mechanisms are merged into a unified extraction device allowing the direct extraction of the analytes from biological matrix without any pretreatment process. The main parameters (sample pH and volume, adsorption and elution time, volume of elution volume etc.) affecting the extraction efficiency of the CPME method were systematically investigated and optimized. The determination of ibuprofen was performed using UHPLC-PDA. The reported method was validated in terms of linearity, selectivity, accuracy, and precision, limit of detection and limit of quantification using the total error concept. Employing the accuracy profiles – as a graphical decision-making tool – the β-expectation tolerance intervals did not exceed the acceptance criteria of ± 15% meaning that 95% of future results will be included in the defined bias limits. The limit of detection (LOD) of the method was adequate, corresponding to 14 ng mL−1. The relative bias in the spiking levels was acceptable being in the range of −4.1 and +3.9% while the relative standard deviation (RSD) was lower than 4.6%. Moreover, the sol–gel sorbent integrated microextraction capsules were found to be reusable for at least 20 extraction cycles. The CPME protocol was successfully employed for the analysis of real urine samples obtained by a healthy volunteer. Finally, the developed CPME method was characterized by absence of matrix-effect and thus its application can be potentially expanded to other types of biological matrices.

Pd–Fe3O4 Janus nanozyme with rational design for ultrasensitive colorimetric detection of biothiols

Although nanozyme-based colorimetric assays have been broadly used for biosensing, some limitations such as low catalytic activity of nanozyme, poor sensitivity to analytes and lack of understanding the structure-activity relationship remain unsolved. In this work, we developed an ultrasensitive colorimetric method for biothiols detection based on density functional theory-assisted design of janus Pd–Fe3O4 nanozyme. The Pd–Fe3O4 dumbbell-like nanoparticles (DBNPs) prepared by seed-mediated approach shows a uniform heterodimeric nanostructure. Ultrasensitive biothiols detection is achieved from two aspects. On one hand, due to the synergistic effect between Pd and Fe3O4 in the dumbbell structure, Pd–Fe3O4 DBNPs show enhanced peroxidase-mimic activity compared to the individual components. On the other hand, when the target biothiols molecule is present, its inhibition effect on the janus Pd–Fe3O4 nanozyme is also significantly enhanced. The above results are confirmed both in experiment and theoretical calculation. Based on the rational design, a simple, highly selective and urtrasensitive colorimetric and quantitative assay for biothiols is developed. The limit of detection (LOD) can reach as low as 3.1 nM in aqueous solution. This assay is also successfully applied to the detection of biothiols in real urine samples. Moreover, the Pd–Fe3O4 nanozyme is used to discriminate biothiols levels in normal and cancer cells with high sensitivity at the cell density of 15,000/mL, which demonstrates its great potential in biological and clinical analysis. This work not only shows the great promise of janus bimetallic nanozymes’ excellent functionalities but also provides rational guidelines to design high-performance nanozymes for biosensing and biomedical applications.

Electrochemical detection of dopamine with negligible interference from ascorbic and uric acid by means of reduced graphene oxide and metals-NPs based electrodes

Dopamine is an important neurotransmitter involved in many human biological processes as well as in different neurodegenerative diseases. Monitoring the concentration of dopamine in biological fluids, i.e., blood and urine is an effective way of accelerating the early diagnosis of these types of diseases. Electrochemical sensors are an ideal choice for real-time screening of dopamine as they can achieve fast, portable inexpensive and accurate measurements. In this work, we present electrochemical dopamine sensors based on reduced graphene oxide coupled with Au or Pt nanoparticles. Sensors were developed by co-electrodeposition onto a flexible substrate, and a systematic investigation concerning the electrodeposition parameters (concentration of precursors, deposition time and potential) was carried out to maximize the sensitivity of the dopamine detection. Square wave voltammetry was used as an electrochemical technique that ensured a high sensitive detection in the nM range. The sensors were challenged against synthetic urine in order to simulate a real sample detection scenario where dopamine concentrations are usually lower than 600 nM. Our sensors show a negligible interference from uric and ascorbic acids which did not affect sensor performance. A wide linear range (0.1–20 μm for gold nanoparticles, 0.1–10 μm for platinum nanoparticles) with high sensitivity (6.02 and 7.19 μA μM-1 cm-2 for gold and platinum, respectively) and a low limit of detection (75 and 62 nM for Au and Pt, respectively) were achieved. Real urine samples were also assayed, where the concentrations of dopamine detected aligned very closely to measurements undertaken using conventional laboratory techniques. Sensor fabrication employed a cost-effective production process with the possibility of also being integrated into flexible substrates, thus allowing for the possible development of wearable sensing devices.

Determination of multiple drugs of abuse in human urine using dispersive liquid–liquid microextraction and capillary electrophoresis with PDA detection

A new method was developed for pre-concentration and determination of multiple drugs of abuse in human urine using dispersive liquid–liquid microextraction (DLLME) and capillary electrophoresis (CE) with photodiode array detection. The method was based on the formation of tiny droplets of an organic extractant in the prepared sample solution using water-immiscible organic solvent (chloroform) dissolved in water-miscible organic dispersive solvent (isopropyl alcohol). The organic phase, which extracted eight drugs of abuse from the prepared urine solution, was separated by centrifugation. The sedimented phase was transferred into a small volume CE auto-sampler vial with 10 µL of 1% HCl methanol solution and evaporated to dryness. The residue was reconstituted in lidocaine hydrochloride (internal standard) aqueous solution and introduced by electrokinetic injection into CE. Under the optimum conditions, acceptable linear relationship was observed in the range of 3.0–500 ng/mL with the correlation coefficient ( r ) of 0.9982–0.9994 for spiked urine samples. The limit of detection (LOD) (S/N = 3) was estimated to be 1.0 ng/mL. A recovery of 75.7%–90.6% was obtained for spiked samples. The mean relative error (MRE) was within ±7.0% and the relative standard deviation (RSD) was less than 6.9%. The proposed DLLME-CE procedure offers an alternative analytical approach for the sensitive detection of drugs of abuse in real urine samples. Key points: The dispersive liquid-liquid microextraction (DLLME) was involved for the determination of drugs in urine with capillary electrophoresis with photodiode array detection (CE-PDA). Good linearity, sensitivity, recovery and precision were achieved. The proposed method was eco-friendly with microliter scale solvent consumption.

Synergistically Interfaced Bifunctional Transition Metal Selenides for High‐Rate Hydrogen Production Via Urea Electrolysis

AbstractThe realization of carbon‐neutral energy is regarded a prime challenge as the environment and energy have become two key issues facing modern society. Here, synergistically interfaced transition metal selenides are studied for hydrogen production via urea electrolysis with concurrent environmental treatment. Extremely low overpotentials of 210 mV, 250 mV, and 1.41 V vs. RHE were observed at 100 mA cm−2 for HER, OER and UOR, respectively with a 98.3 % faradaic efficiency. A notably low cell voltage of 1.6 and 1.84 V was required at 200 mA cm−2 for urea and water electrolysis, respectively along with a remarkably stable performance for 4 days. Additionally, A 1.45‐fold increase in H2 production rate was observed for urea electrolysis [26.6 μmol min−1] when compared with water electrolysis [18 μmol min−1] decreasing the power consumption by 37 %. Real human urine electrolysis was conducted with excellent performance requiring a cell voltage of only 1.9 V at 200 mA cm−2, attributed to the synergistic intermediate‐active site interaction, improved charge transfer capability, and slow surface transformation‐induced activation.

Urea recovery from stabilized urine using a novel ethanol evaporation and recrystallization process

Urea is a raw material in the production of various chemicals and is a key nitrogen-based fertilizer. The conventional process to manufacture synthetic urea operates at high temperatures and pressures and is therefore energy intensive. The aim of this work was to investigate the feasibility of recovering and purifying urea crystals from human urine using a novel ethanol evaporation and recrystallization process that exploits the solubility differences of urea and impurities in water and ethanol. This approach could provide an alternative method to produce urea that operates at atmospheric pressure and low temperatures (< 30°C).Synthetic and real human urine was treated with Ca(OH)2 to prevent urea hydrolysis and then dried to recover the solids. These solids were dissolved in a predetermined amount of ethanol and the urea present was recrystallized. A complex synthetic urine solution (with various organics and inorganics) had a urea solubility of 56.7 g L−1 at 22°C. It was determined that the solubility of urea in ethanol increased when more organics were present in the solution. Urea was recovered from inorganic synthetic urine (SI), organic synthetic urine (SO) and real human urine (RU) with yields of 88%, 77% and 67%, respectively. The purity of urea increased from 41%, 41% and 43% to 91%, 76% and 76% for SI, SO and RU using the ethanol evaporation and recrystallization process.

Electrochemical determination of epinephrine based on Ti3C2Tx MXene-reduced graphene oxide/ITO electrode

EP is an important natural catecholamine neurotransmitter in the central nervous system, and the change of EP concentration will lead to many diseases. Therefore, rapid and sensitive detection of EP is of great significance for clinical research. The Ti3C2Tx MXene dispersion obtained by in-situ HF etching Ti3AlC2 was mixed with graphene oxide (GO) dispersion synthesized by the modified Hummers method. After freeze drying and heat-treatment, the reduced graphene oxide/Ti3C2Tx MXene (GMA) was obtained and then the GMA was moved onto indium tin oxide (ITO) as the GMA/ITO working electrode for electrochemical detection of epinephrine (EP). The results are as follows: Ti3C2Tx MXene with a diameter of approximately 150 nm is uniformly distributed on the surface of the 3D graphene. The three-dimensional structure of GMA facilitates the entry of bioactive molecules and increases the contact area. GMA/ITO has a high sensitivity for the determination of EP 3.74 μA·μM−1·cm−2. Moreover, the electrode shows a very low detection limit, well repeatability and stability, and it can detect the EP content in real urine samples.

Ultrasensitive and High Reproducible Detection of Urinary Metabolites Using the Tip–Contact Extraction Method Coupled with Negative LDI-MS

More and more evidence has proved that urinary metabolites can instantly reflect disease state. Therefore, ultra-sensitive and reproducible detection of urinary metabolites in a high-throughput way is urgently desirable for clinical diagnosis. Matrix-free laser desorption/ionization mass spectrometry (LDI-MS) is a high-throughput platform for metabolites detection, but it is encountered by severe interference from numerous salts in urine samples, because the crystallized urine salt on dried samples could result in poor reproducibility in LDI-MS detection. The present work proposed a tip-contact extraction (TCE) technique to eliminate interference from the urine salt. Vertical silicon nanowire arrays decorated with the fluorinated ethylene propylene film (FEP@VSiNWs) could effectively extract metabolites from the urine sample dropping on its surface. High salt tolerance was observed in the subsequent LDI-MS detection of the metabolites extracted on the tip of FEP@VSiNWs even in the presence of 1 M urea. Stable and reproducible mass spectra for non-target metabolic analysis were obtained in real urine samples with different dilution folds. Urinary metabolites collected from bladder cancer (BC) patients were reliably profiled by the TCE method coupled with negative LDI-MS. Based on this platform, potential metabolic biomarkers that can distinguish BC patients and normal controls were uncovered.

Development of an Accurate Mass Retention Time Database for Untargeted Metabolomic Analysis and Its Application to Plasma and Urine Pediatric Samples.

Liquid-chromatography coupled to high resolution mass spectrometry (LC-HRMS) is currently the method of choice for untargeted metabolomic analysis. The availability of established protocols to achieve a high confidence identification of metabolites is crucial. The aim of this work is to describe the workflow that we have applied to build an Accurate Mass Retention Time (AMRT) database using a commercial metabolite library of standards. LC-HRMS analysis was carried out using a Vanquish Horizon UHPLC system coupled to a Q-Exactive Plus Hybrid Quadrupole-Orbitrap Mass Spectrometer (Thermo Fisher Scientific, Milan, Italy). The fragmentation spectra, obtained with 12 collision energies, were acquired for each metabolite, in both polarities, through flow injection analysis. Several chromatographic conditions were tested to obtain a protocol that yielded stable retention times. The adopted chromatographic protocol included a gradient separation using a reversed phase (Waters Acquity BEH C18) and a HILIC (Waters Acquity BEH Amide) column. An AMRT database of 518 compounds was obtained and tested on real plasma and urine samples analyzed in data-dependent acquisition mode. Our AMRT library allowed a level 1 identification, according to the Metabolomics Standards Initiative, of 132 and 124 metabolites in human pediatric plasma and urine samples, respectively. This library represents a starting point for future metabolomic studies in pediatric settings.