Drugs In Human Serum Research Articles

Improving the Efficiency of Luminescent Zn(II)-Modified N-Doped GOQD Nanomaterials in Parkinson's Disease Treatment: A Theoretical Mechanistic Framework Exploring Doping Effect.

Levodopa, a widely prescribed drug in Parkinson's disease treatment, stands as the foremost prodrug of dopamine. An affordable self-testing kit is utilized to monitor levodopa content in anti-parkinson drugs in human serum. A photoluminescent trinuclear Zn(II) complex [Zn3(L)2(κ1-OAc)2(κ2-OAc)2] has been synthesized, which cleaves into mononuclear ZC in aqueous solution. ZC was found to detect L-Dopa in Tris-HCl buffer, exhibiting a moderate decrease in PL-emission. The real-life utility of the ZC probe is limited, for its lower sensitivity (LOD 35.3 μM) and separation challenges. Therefore, an interface between homogeneous and heterogeneous supports has been explored, leading to the strategic development of NGOZC, where ZC was grafted onto NGOQD (Graphene oxide quantum dots). This material enables naked- eye detection under both ambient and UV light with color change from bright cyan to green, followed by dark. The nitrogen doping effect was investigated by several comparative investigations involving the synthesis of ZC-grafted GOQD, leading to enhanced quenching performance. Steady-state and time-resolved fluorescence titration study, morphological analysis, and computational calculations have been performed to get insights into the sensing mechanism. To the best of our knowledge, this as-synthesized NGOZC (LOD 1.78 nM) represents a promising strategy and platform for applications in biosensors, especially for Parkinson's and Alzheimer's diseases.

Solid-phase extraction coupled to automated centrifugal microfluidics SERS: Improving quantification of therapeutic drugs in human serum

Surface-enhanced Raman spectroscopy (SERS) is a powerful method in analytical chemistry, but its application in real-life medical settings has been limited due to technical challenges. In this work, we introduce an innovative approach that is meant to advance the automation of microfluidics SERS to improve reproducibility and label-free quantification of two widely used therapeutic drugs, methotrexate (MTX) and lamotrigine (LTG), in human serum. Our methodology involves a miniaturized solid-phase extraction (μ-SPE) method coupled to a centrifugal microfluidics disc with incorporated SERS substrates (CD-SERS). The CD-SERS platform enables simultaneous controlled sample wetting and accurate SERS mapping. Together with the assay we implemented a machine learning method based on Partial Least Squares Regression (PLSR) for robust data analysis and drug quantification. The results indicate that combining μ-SPE with CD-SERS (μ-SPE to CD-SERS) led to a substantial improvement in the signal-to-noise ratio compared to combining CD-SERS with ultrafiltration or protein precipitation. The PLSR model enabled us to obtain the limit of detection and quantification for MTX as 2.90 and 8.92 μM, respectively, and for LTG as 10.76 and 32.29 μM. We also validated our μ-SPE to CD-SERS method for MTX against HPLC and immunoassay (p-value <0.05), using patient samples undergoing MTX therapy. In addition, we achieved a satisfactory recovery rate (80%) for LTG when quantifying it in patient samples. Our results show the potential of this newly developed approach as a strategy for therapeutic drugs in point-of-care clinical settings and highlight the benefits of automating label-free SERS assays.

UPLC-MS/MS determination of 71 neuropsychotropic drugs in human serum

In this study, a UPLC-MS/MS method was developed for the rapid detection of 71 neuropsychotropic drugs in human serum for drug concentration monitoring and toxicity screening. The analytes were separated from the biological matrix by protein precipitation using a methanol-acetonitrile solvent mixture. The chromatographic separation was performed on a Kromasil ClassicShell C18 column (2.1*50 mm, 2.5 μ m) with gradient elution using acetonitrile-0.2 % acetic acid and 10 mM ammonium acetate as the mobile phases (flow rate 0.4 mL/min, column temperature 40 °C, injection volume 5 μL). An electrospray ion source in both positive and negative ion modes with multiple ion monitoring was used. The total run time was 6 min. All compounds were quantified using the isotope internal standard method. Totally, 71 drugs were detected within their linear ranges with correlation coefficients greater than 0.990. The intra- and inter-batch precision relative standard deviations (RSDs) for the low, medium, and high concentration points were less than 15 %, with an accuracy of 90%–110 %. All compounds except Moclobemide N-oxindole are stabilised within 7 days. The relative matrix effect results for each analyte were within ±20 % of the requirements. The method is validated according to Clinical and Laboratory Standards Institute guidelines, easy to use, and has a low cost.

Development of a rapid LC-MS/MS method for simultaneous quantification of ten commonly used antibiotic drugs in human serum

The use of TDM in clinical practice to monitor the plasma levels of antibiotics administered to critically ill patients is a well-established approach that allows for optimization of the patient's response to drug therapy, considering the characteristics of the drug, the clinical and physiological status of the patient and any peculiar of the pathogen that caused the clinical picture. In our laboratory, we have developed a single LC-MS/MS analysis for dosing the serum concentration of an antibacterial panel composed of eight antibacterial and two selective inhibitors. The method presented used a certified material furnished by a commercial company and was internally validated using the EMA guidelines. The results have shown high sensitivity, precision, and accuracy, a lower matrix effect combined with simple sample preparation and a time-saving procedure. We have evaluated the recovery rate and matrix effect by testing serum samples without pathological index and serum pools obtained from haemolysed, icteric, or lipemic samples. The assay has shown a recovery range between 94% and 101%.

Development, Validation, and Clinical Application of an Ultra-High-Performance Liquid Chromatography Coupled With Tandem Mass Spectrometry Method for the Determination of 10 Antituberculosis Drugs in Human Serum.

Linezolid, moxifloxacin, rifapentine, rifabutin, cycloserine, clofazimine, bedaquiline, levofloxacin, prothionamide, and ethionamide are commonly used second-line antituberculosis (anti-TB) drugs. To support therapeutic drug monitoring in regular clinical practice, the authors sought to develop a method based on ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) that would allow for the simultaneous quantification of multiple second-line anti-TB drugs in human serum. Analytes were extracted from human serum by protein precipitation. UHPLC-MS/MS was performed using a gradient at a flow rate of 0.3 mL/min, and each sample was taken for 7.5 minutes. The mass spectrometry scanning mode used was electrospray ionization with multiple reaction monitoring in the positive mode. Validation showed that endogenous substances in the sample did not interfere with the assay, and the relationship between X and Y was highly linear, with a coefficient of determination (R 2 ) >0.9954 for each curve. The accuracy (85.0%-114.7%) and precision (intraday: 0.27%-9.32%; interday: 0.20%-7.66%) were less than 15.0%, and the internal standard-normalized matrix effects were consistent (coefficient of variation ≤4.40%). The analytes were stable in the final extract and human serum under various storage conditions (recovery: 87.0%-115.0%). The clinical applicability of the method was demonstrated by quantitative determination of analytes in serum samples obtained from patients with TB. Reproducibility of the drug concentrations measured in clinical samples was confirmed by incurred sample reanalysis. A simple and reliable analytical method was developed and validated for the simultaneous determination of 10 anti-TB drugs in human serum using UHPLC-MS/MS. Quantitation of anti-TB drugs in clinical samples confirmed that the assay is suitable for therapeutic drug monitoring in regular clinical practice.

Preparation of restricted-access boronate affinity adsorbent with excellent anti-protein adsorption property for directly extracting small cis-diol molecules from biological matrices

Boronate affinity adsorbents are of great promise in the enrichment of small cis-diol-containing molecules (cis-diols) from biological matrices. This work develops a restricted-access boronate affinity mesoporous adsorbent, in which boronate sites are only distributed on the internal surface of mesopores and the external surface is a strongly hydrophilic layer. The adsorbent has high binding capacities (30.3 mg g−1, 22.9 mg g−1 and 14.9 mg g−1 for dopamine, catechol and adenosine, respectively) in spite of removal of the boronate sites on the external surface of adsorbent. The adsorption specific of adsorbent towards cis-diols was assessed by dispersive solid-phase extraction (d-SPE) method, and the results show that the adsorbent can selectively extract small cis-diols in the biosamples while exclude proteins completely. Under the optimal d-SPE, the nucleosides and cis-diol drugs in human serum were successfully analyzed by coupling d-SPE with high-performance liquid chromatography. Where, the detection limits are between 6.1 and 13.4 ng mL−1 for four nucleosides, and 24.9 and 34.3 ng mL−1 for two cis-diol drugs; the relative recoveries of all the analytes vary from 84.1% to 110.1% (RSDs <13.4%, n = 6). The results indicate that the adsorbent can directly treat the real biosamples without the necessary protein precipitation steps in advance, thus simplifying the analysis process.

A High-Performance Liquid Chromatography—Mass Spectrometry Method for Simultaneous Determination of Vancomycin, Meropenem, and Valproate in Patients with Post-Craniotomy Infection

Vancomycin (VAN), meropenem (MER), and valproate (VPA) are commonly used to treat intracranial infection post-craniotomy and prevent associated epilepsy. To monitor their levels, we developed a novel bioassay based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneous determination of these three drugs in human serum and cerebrospinal fluid (CSF). Sample preparation by protein precipitation using acetonitrile was followed by HPLC on a Zorbax 300SB-C8 column (150 mm × 4.6 mm, 5 μm) maintained at 40 °C. The lower limit of quantification (LLOQ) was 5 ng/mL for MER, 0.1 μg/mL for VAN, and 1 μg/mL for VPA in serum and 50 ng/mL for MER, 1 μg/mL for VAN, and 2 μg/mL for VPA in CSF. This method was validated with satisfactory linearity, sensitivity, precision, accuracy, recovery, matrix effects, and stability for all analytes. The assay was then successfully applied to evaluate VPA, MER, and VAN levels in serum and CSF from patients with intracranial infection administrated by intrathecal injection. Compared with intravenous injections, an intrathecal injection can provide sufficient therapeutic effects even if the CSF levels did not reach the effective concentration reported. Our method provided a detection tool to study the effective concentrations of these three drugs in CSF from patients administered via intrathecal injection.

Red emission carbon dots for mitoxantrone detection

Red-emitting carbon dots were designed for the first time as the fluorescent probe for the determination of mitoxantrone (MITX) anticancer drug in human serum based on the inner filter effect (IFE). With the increase of MITX concentration, the single emission fluorescence intensity of the red carbon dots (R-CDs) at 655 nm gradually decreased and the emission peak position red-shifted to 661 nm. The developed R-CDs detection probe was sensitive to MITX with a wide linear detection range of 0.096–30 µM and a low limit of detection (LOD) of 0.032 µM. Moreover, the proposed method had been successfully applied to the determination of MITX in human serum samples, showing exhibited good operability, low cost, and high accuracy.

An in-depth analysis of four classes of antidepressants quantification from human serum using LC–MS/MS

Depression is a growing global crisis, with females at a higher rate of diagnosis than males. While the percentage of patients on prescribed antidepressants have tripled over the last two decades, we are still at a crossroad where the discrepancy lies between finding a drug to suit a patient and monitoring the abundance of it in the body to prevent unwanted side effects. Liquid Chromatography tandem mass spectrometry (LC–MS/MS) has garnered the attention of clinicians as a technique to accurately monitor therapeutic drugs in human serum with high specificity and accuracy. This may be a potential solution, but the challenge persists in the realm of sample preparation, where a method is automatable. We have developed and validated an LC–MS/MS-based assay for simultaneous quantification of 4 different classes of commonly prescribed antidepressants in women that is automated using a JANUS G3 Robotic Liquid Handler. Our method utilizes a simple sample preparation technique, utilizing only 20 μL of a serum sample, to accurately measure Bupropion, Citalopram, Desipramine, Imipramine, Olanzapine, Sertraline and Vilazodone across a range of 1.0 to 230 ng/mL. Our method exhibits a linearity of R2 ≥ 0.99 when detected in MRM mode and % CV of ≤ 20% for all analytes across the board. In addition, we have designed a prototype that can be utilized at a clinical mass spectrometry lab and assessed the long-term use of this prototype using an accelerated stability study. Overall, our developed method has the potential to be translated to clinical settings to monitor postpartum depression for a large number of patient samples using automation.

Highly Sensitive In-Capillary Derivatization and Field Amplified Sample Stacking to Analyze Narcotic Drugs in Human Serum by Capillary Zone Electrophoresis

An in-capillary derivatization (in-CAP-D) integrated with field amplified sample stacking (FASS) has been developed for the determination of morphine (MOR) and its metabolite, morphine-6-glucuronide (MOR-6-G) in human serum using capillary zone electrophoresis (CZE) and fluorescence detection (in-Cap-D-FASS-CZE). Acetonitrile was employed in removing proteins and extracting MOR and MOR-6-G into the clear supernatant containing codeine (COD) as an internal standard (IS). The derivatization was achieved in an in-capillary mode by introducing the acetonitrile-treated samples into a running electrolyte containing an oxidizing agent of potassium ferricyanide, whereas MOR, MOR-6-G and COD were oxidized into dimer derivatives with highly fluorescent intensity. The effectiveness and sensitivity of the in-Cap-D-FASS-CZE method were affected by many parameters, and the following conditions were found to be optimal: 70 m Mdisodium tetraboratedecahydrate (pH, 10.5), 0.30 mM ferrricyanide and a separation voltage of 10 kV. In order to perform the FASS, samples were electrokinetically injected for 20 s at 20 kV into the capillary that was pre-field with a 4 s water plug. Analysis was performed at ambient temperature (22 ± 1 °C). The method’s validation revealed good linearity with respect to peak area ratios of MOR and MOR-6-G with the IS and the corresponding concentrations over the ranges of 1–2000 and 1.2 to 2000 ng/mL, respectively. Following one oral dose of controlled-release MOR sulphate tablet, the validated in-Cap-D-FASS-CZE method successfully enabled the determination of MOR and MOR-6-G in clinical serum samples.

The Experimental Design Approach in Square‐Wave Voltammetric Determination of Tamoxifen by NiO‐CPE**

AbstractDue to the explosive global increase of various cancers, the need to introduce/develop novel catalysts/sensors for quantitative determination of cancer drugs is emphasized. Nickel oxide nanoparticles (NiO‐NPs) calcined at 200 °C were used as a modifier of carbon paste electrode (CPE) to quantify tamoxifen (TAM) in an aqueous solution. The square wave voltammetry (SqW) was used due to its high sensitivity. The modified NiO‐CPE showed an SqW anodic peak current with a peak potential of about 420 mV in the NaOH‐supporting electrolyte. This peak current was decreased when TAM analyte was added to the test solution. Thus, this reduced peak current (Δi) was used to quantify TAM in solution. The experimental design used the response surface methodology (RSM) approach to study the simultaneous interaction effects between the influencing variables. The optimized run was associated with a 10 % NiO ingredient in the CPE, 0.3 M NaOH, an amplitude of 200 mV, a step potential of 3 mV, and a frequency of 25 Hz. A proportional behavior was obtained between the mentioned Δi and TAM concentration in the range of 10–60 nM. The detection (LOD) and quantification (LOQ) limits were 1.81±0.35 and 6.05±0.24 nM, respectively. Interfering and recovery results confirmed the applicability of the proposed NiO‐CPE electrode for TAM determination in complex matrixes and the direct assay of the drug in human serum.

Phenotypic Screening of the Reframe Drug Repurposing Library to Discover New Drugs for Treating Sickle Cell Disease

Stem cell transplantation and genetic therapies offer potential cures for patients with sickle cell disease (SCD) but these options require advanced medical facilities and are expensive. Consequently, these treatments are not available, and will not be available for many years, for the vast majority of the millions of patients suffering from this disease, who live in under-resourced countries. Hydroxyurea is considered standard therapy for patients with SCD and would be even more therapeutic if it increased fetal hemoglobin in all red blood cells, which it does not. What is urgently needed now is an inexpensive oral drug, in addition to hydroxyurea, that inhibits sickle-hemoglobin polymerization in all cells. To this end, we have just completed a phenotypic screen of the 12,657 compounds of the Scripps ReFrame drug repurposing library using our recently developed high-throughput assay to measure sickling times following deoxygenation to 0% oxygen of red cells from individuals with sickle trait (HbAS), the heterozygous condition. The ReFrame library is a very important collection because the compounds are either FDA-approved drugs or have been tested in clinical trials with extensive drug annotation in an open-access format. Compounds, which inhibit sickling in our assay at concentrations that can be achieved in human serum, without side effects that would be deleterious for SCD patients, can be brought to clinical trials with very few or even no pre-clinical studies. From dose-response measurements, we discovered that 106 of the 12,657 compounds are anti-sickling at concentrations ranging from 31 nM to 10 microM. We also showed that compounds that inhibit sickling of trait cells are effective with SCD cells. As many as 21 of the 106 anti-sickling compounds should emerge as drugs. This estimate is based on a comparison of the distribution of inhibitory concentrations in our assay with the known distribution of free concentrations of oral drugs in human serum (see Figure). Moreover, the expected therapeutic effect for each level of inhibition can be predicted from our measurements of sickling times for cells from individuals with sickle syndromes of differing clinical severity. We believe our results represent a breakthrough in drug therapy by serving as a catalyst for us and others to develop one or more of these 106 anti-sickling compounds into effective drugs for treating SCD. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Drug discovery by a basic research scientist.

I was fortunate to do my military service during the Vietnam era as a medical officer at the National Institutes of Health (NIH) in Bethesda, Maryland. My first research at NIH was concerned with making a variety of optical measurements on nucleic acid bases and proteins, including single crystal spectra in linearly polarized light and near infrared circular dichroism, interpreting the spectra using molecular orbital and crystal field theories. What I do now is drug discovery, a field at the opposite end of the scientific spectrum. This article gives a brief account of my transition from spectroscopy to sickle cell hemoglobin polymerization to protein folding to drug discovery for treating sickle cell disease. My lab recently developed a high throughput assay to screen the 12,657 compounds of the California Institute of Biomedical Research ReFrame drug repurposing library. This is a precious library because the compounds have either been FDA approved or have been tested in clinical trials. Since the 1970s numerous agents have been reported in the literature to inhibit HbS polymerization and/or sickling with only one successful drug, hydroxyurea, and another of dubious value, voxelotor, even though it has been approved by the FDA. Our screen has discovered 106 anti-sickling agents in the ReFrame compound library. We estimate that as many as 21 of these compounds could become oral drugs for treating sickle cell disease because they inhibit at concentrations typical of the free concentrations of oral drugs in human serum.

Phenotypic screening of the ReFRAME drug repurposing library to discover new drugs for treating sickle cell disease

Stem cell transplantation and genetic therapies offer potential cures for patients with sickle cell disease (SCD), but these options require advanced medical facilities and are expensive. Consequently, these treatments will not be available for many years to the majority of patients suffering from this disease. What is urgently needed now is an inexpensive oral drug in addition to hydroxyurea, the only drug approved by the FDA that inhibits sickle-hemoglobin polymerization. Here, we report the results of the first phase of our phenotypic screen of the 12,657 compounds of the Scripps ReFRAME drug repurposing library using a recently developed high-throughput assay to measure sickling times following deoxygenation to 0% oxygen of red cells from sickle trait individuals. The ReFRAME library is a very important collection because the compounds are either FDA-approved drugs or have been tested in clinical trials. From dose-response measurements, 106 of the 12,657 compounds exhibit statistically significant antisickling at concentrations ranging from 31 nM to 10 μM. Compounds that inhibit sickling of trait cells are also effective with SCD cells. As many as 21 of the 106 antisickling compounds emerge as potential drugs. This estimate is based on a comparison of inhibitory concentrations with free concentrations of oral drugs in human serum. Moreover, the expected therapeutic potential for each level of inhibition can be predicted from measurements of sickling times for cells from individuals with sickle syndromes of varying severity. Our results should motivate others to develop one or more of these 106 compounds into drugs for treating SCD.

P115 Reversed-phase high-performance liquid chromatography as rapid and simple method for quantifications of terbinafine drug in human serum from dermatophytosis cases

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM ObjectivesThe alarming situation of treatment failure cases in dermatophytosis and resistance to the first-line drug (terbinafine) is a worrisome condition for the management of tinea cases. However, studies also reported non-responders to terbinafine treatment even when the isolates are susceptible to this drug in vitro. Thus, evaluating the pharmacokinetic profile of terbinafine might help better manage dermatophytosis. This study was conducted to standardize and validate a rapid and simple reversed-phase high-performance liquid chromatography (HPLC)-based protocol for terbinafine in serum/plasma of dermatophytosis cases.MethodsHPLC analysis was standardized for terbinafine drug on an Agilent 1290 infinity system (Agilent Technologies InC., USA). Chromatographic parameters including mobile phase [acetonitrile (A), methanol (M), and water (W)], flow rate (0.7-1.5 ml/min), injection volume (20 μl), and various wavelengths ranging from 220 to 265 nm under isocratic conditions were assessed and optimized. The mobile phase consisted of a filtered and degassed mix of A: W and M: W with various ratios of 85:15, 60:40, 50:50, and M-100%, respectively. Quality control samples were prepared in drug-free serum by spiking with the terbinafine at 0.0312-100 μg/mL concentrations. An equal volume of serum and acetonitrile (A) were mixed. The mixture was vigorously vortexed for 30 s, followed by high-speed centrifugation at 13 000 rpm at 40°C for 10 min. The supernatant was transferred into the chromatographic vials and placed in the autosampler of HPLC for injection. The standardized method was tested in 6 dermatophytosis patients’ serum/plasma samples collected at 3-time points (first, second, and third week of start of antifungal).ResultsLinearity of calibration standard for terbinafine was optimized at 250C at a flow rate of 1.0 ml/min, injection volume 20 μl, 8 minutes run time with the standardized wavelength at 245 nm under isocratic conditions. The best suitable graph was determined by plotting the area under the curve (AUC) and peak height separately against the drug concentrations measured by reversed-phase- HPLC for terbinafine drugs (Fig. 1a and b). The standardized mobile phase consisted of filtered and degassed Methanol (100, v/v). The chromatographic separation was achieved on an Agilent C18 column, and 4.3 ± 1 time represents the peak for terbinafine drug. Based on the standardized protocol, six tinea cases were included for validation, and the therapeutic range achieved for terbinafine in clinical samples was 0.6 to 1.13 μg/ml.ConclusionsThe standardization of HPLC method was successfully applied to quantify terbinafine in spiked samples with terbinafine drug and showed no observable interferences at the standardized parameter. Further evaluation with larger number of samples is warranted.

(Invited) Fast and Generalizable Electrochemical Sensing of Small Molecules, Peptides, and Proteins Using a Nucleic Acid Nanostructure with Analyte-DNA Conjugates

Sensors based on electrochemical (EC) readout offer low cost, miniaturization, and adaptability to the point-of-care (POC). Nonetheless, most EC sensors are specialized to a particular target, and there remains a need for a robust EC biosensor platform for the multitude of biomarkers that are not EC-active, do not undergo enzymatic conversion, or are not suited for potentiometry [1,2]. Impressively, aptamer-based EC sensors have been proven for sensing in living animals with temporal resolution as low as a few seconds [3], yet most method development has been target-focused, lacking generalizability [4]. Presently, the clinical EC toolbox is a conglomerate of targeted methods, and there is a pressing need to develop an EC platform amenable to rapid, generalizable, quantitative readout of multiple classes of clinically relevant targets.Direct EC sensing without added reagents or amplification steps should be ideal for this purpose. For example, the Kelley group recently developed a reagentless “molecular pendulum” EC sensor for a broad range of protein analytes [5]. Our group has been working to address this need and expand to more analyte classes for several years, and in 2019 we designed a versatile DNA-nanostructure architecture attached to gold electrode surfaces [6]. Initially, our sensors were validated with biotechnology controls, antibodies, and with a small molecule immunomodulatory drug in human serum. In this presentation, we discuss the expansion of the generalizability of our sensor platform, chiefly through custom synthesis of varied DNA-analyte bioconjugates to incorporate within the DNA-nanostructure.For peptide sensing, DNA-peptide conjugates were synthesized, purified, then ligated to the DNA-nanostructure. Sensors were validated for quantifying exendin-4 (4.2 kDa)—a human glucagon-like peptide-1 receptor agonist important in diabetes therapy—for the first time using direct EC methods, with an LOD of 6 nM [7]. Sensors for larger proteins were made using DNA-epitope conjugates. The antibody-binding epitope of creatine kinase MM (CK-MM) was conjugated into the nanostructure, allowing CK-MM sensing in the 10 to 100 nM range. Finally, DNA-steroid bioconjugates have been incorporated into the sensors. Sensing of testosterone throughout the clinically relevant range (for males) was accomplished from 1 to 50 nM (LOD of 0.9 nM), and cortisol could be easily detected in the 1 to 100 nM range, well below the 90 – 550 nM range in blood and nicely encompassing the 6 – 75 nM range in saliva.All of these sensors were functional in 98% human serum, and several detection ranges overlap with the clinical/therapeutic ranges, boding well for future applications in biosensing or therapeutic drug monitoring. Overall, this new DNA nanostructure platform provides a generalizable sensor with minimal workflow, direct-readout, and the capability to expand EC sensing to a wide variety of clinically important analytes.

The evaluation of drug-plasma protein binding interaction on immobilized human serum albumin stationary phase, aided by different computational approaches

The drug-human serum albumin binding interaction was evaluated on a stationary phase immobilized with human serum albumin using a mixture of phosphate buffer (pH 7.0) and acetonitrile modifier as mobile phase. The 33 compounds that have a wide structural and therapeutic diversity were analyzed by performing a large number of experiments. The interaction mechanism was interpreted based on: i) retention characteristics of structurally related compounds, ii) retention modeling, iii) quantitative structure retention relationship (QSRR), and iv) molecular docking. Small structural differences of related compounds (e.g., reflected in different lipophilicity and polarity) have been found to affect their different binding to human serum albumin. It was found that drug retention in HSA column can be successfully described by using the quadratic function. The isocratic (logk(14%)) and extrapolated (b0(LSS)) retention factors showed the highest correlation (r > 0.76) with the constant that defines the binding affinity for human serum albumin (ACD/I-Lab). Therefore, selected chromatographic parameters can demonstrate reliable applicability for rapid screening of drug-plasma protein binding in drug discovery. In QSRR study, the resulting SVM/logk(14%) and MLR/b0(LSS) models display high internal and external predictive power. The constitutional properties (double bonds, aromatic rings, benzyl, allyl, -amino and -sulfur containing functional groups) supported by the charged parts of surface area had a significant impact on human serum albumin-binding affinity, which was also confirmed with molecular docking study. The high structural diversity of the data set provides wide applicability of tested chromatographic conditions and constructed models for defining the pharmacokinetic profile and possible structural modifications that can increase plasma protein binding of newly synthesized, pharmaceutically important compounds.

Engineering hairy cellulose nanocrystals for chemotherapy drug capture

Cancer is one of the leading causes of death worldwide, affecting millions of people every year. Although chemotherapy remains one of the most common cancer treatments in the world, the severe side effects of chemotherapy drugs impose serious concerns to cancer patients. In many cases, the chemotherapy can be localized to maximize the drug effects; however, the drug systemic circulation induces undesirable side effects. Here, we have developed a highly efficient cellulose-based nanoadsorbent that can capture more than 6,000 milligrams of doxorubicin (DOX), one of the most widely used chemotherapy drugs, per gram of the adsorbent at physiological conditions. Such drug capture capacity is more than 3,200% higher than other nanoadsorbents, such as DNA-based platforms. We show how anionic hairy cellulose nanocrystals, also known as electrosterically stabilized nanocrystalline cellulose (ENCC), bind to positively charged drugs in human serum and capture DOX immediately without imposing any cytotoxicity and hemolytic effects. We elucidate how ENCC provides a remarkable platform for biodetoxification at varying pH, ionic strength, ion type, and protein concentration. The outcome of this research may pave the way for developing the next-generation in vitro and in vivo drug capture additives and devices.

Application of NiO[sbnd]CPE in the quantitative determination of loratadine: Experimental design in square wave voltammetry approach

Nickel oxide (NiO) nanoparticles (NPs) were synthesized by a sol-gel method and calcination at 200 °C. The modified carbon paste electrode with NiO NPs showed an increased current in the presence of loratadine (Lor). Thus, the experimental design using the response surface methodology (RSM) approach was applied to study the interaction effects of binary variables in the electrode's response in the square wave voltammetric (SqW) determination of Lor. The optimized run included by 10.5% of NiO modifier, 0.1 M NaOH, the amplitude of 700 mV, step potential of 3 mV, and frequency of 45 Hz. A calibration plot in the range of 30–960 nM with limits of detection (LOD) and quantification (LOQ) of 1.4 ± 0.27 and 4.6 ± 0.4 nM were obtained, respectively. The modified electrode showed good selectivity and applicability for Lor determination in complex matrixes and the direct assay of the drug in human serum. Two mechanism pathways were suggested for the oxidation of Lor by NiOOH. In the first one, the nitrogen atom of the pyridine ring can be oxidized. In contrast, in the second one, the nitrogen atom of isocyanate can be oxidized. In the present oxidizing media, the produced intermediate is more stable than in the first pathway. Here, isocyanate cation radical is produced, which has a resonance form. Further, in this intermediate, CO is an excellent leaving group. Finally, both pathways confirm some intermediates for the oxidized Lor causing an irreversible process.

Fast fabric phase sorptive extraction of selected β-blockers from human serum and urine followed by UHPLC-ESI-MS/MS analysis

A fast fabric phase sorptive extraction method is presented herein for the rapid isolation of selected beta-blocker drugs from human serum and urine. Among many high efficiency sol-gel sorbent coated FPSE membranes, sol-gel CW20 M coated FPSE membrane was identified as the best FPSE membrane for the target beta-blocker drugs possessing logP values ranging from 0.1 (highly polar) to 3.1 (moderately polar). Due to the engineered affinity towards the analytes via complementary intermolecular interactions and high mass transfer rate of the analytes from the bulk sample solution to the FPSE membrane, the extraction is accomplished in relatively short time (15 min) while its high permeability permits the direct extraction of biological samples without any other pretreatment. The advantages of the fabricated extraction membrane were exploited for the determination of six beta-blockers (namely atenolol, nadolol, metoprolol, oxprenolol, labetalol and propranolol) in biological matrices in combination with UHPLC-ESI-MS/MS. Important parameters including extraction time, sample volume, sorbent size, elution solvent, etc. affecting the performance of the extraction were systematically investigated. The linearity of the method was evaluated in the range of 50–5000 ng mL−1 by constructing weighted (1/X) matrix-matched calibration curves. The intra-day and inter-day trueness were ranged between – 17.2 to 13.3% and – 10.8 to 12.6%, respectively. The intra-day and inter-day precision were less than 11.5 and 14.5 %, respectively. The proposed analytical scheme was successfully applied to the determination of the target drugs in human serum and urine.