Glassy carbon electrodes modified with graphitic carbon nitride nanosheets and CoNiO2 bimetallic oxide nanoparticles as electrochemical sensor for Sunitinib detection in human fluid matrices and pharmaceutical samples

A sophisticated electrochemical sensor is presented employing a glassy carbon electrode (GCE) modified with a novel composite of synthesized graphitic carbon nitride (g-C3N4) and CoNiO2 bimetallic oxide nanoparticles (g-C3N4/CoNiO2). The sensor's electrocatalytic capabilities for Sunitinib (SUNI) oxidation were demonstrated exceptional performance with a calculated detection limit (LOD) of 52.0 nM. The successful synthesis and integrity of the composite were confirmed through meticulous characterization using various techniques. FT-IR analysis affirmed the successful synthesis of g-C3N4/CoNiO2 by providing insights into its molecular structure. XRD, FE-SEM, SEM-EDX, and BET analyses collectively validated the material's structural integrity, surface morphology, and electrocatalytic performance. Optimization of key analytical parameters, such as loading volume, concentration, electrolyte solution type, and pH, enhanced the electrocatalytic sensing capabilities of g-C3N4/CoNiO2. The synergistic interaction between g-C3N4 and CoNiO2 bimetallic oxide nanoparticles executed the sensor highly effective in the electrical oxidation of SUNI. Across a concentration range of 0.1-83.8 µM SUNI, the anodic peak current exhibited a linear increase with good precision. Application of the newly developed g-C3N4/CoNiO2 system to detect SUNI in a variety of samples, including urine, human serum, and capsule dosage forms, obtained satisfactory recoveries ranging from 97.1 to 103.0%. This methodology offers a novel approach to underscore the potential of the developed sensor for applications in biological and pharmaceutical monitoring.

A pilot study for colorectal carcinoma screening by instant metabolomic profiles using conductive polymer spray ionization mass spectrometry

BACKGROUND

The rapid and accurate discrimination of colorectal carcinoma (CRC) and polyps at the molecular level enables early intervention of CRC, which can greatly improve the 5-year survival rate of patients. Here we reported the potential of conductive polymer spray ionization mass spectrometry (CPSI-MS) in successfully screening CRC according to the serum metabolic profile.

METHODS

Trace intravenous blood (50 μL) was collected from 60 colorectal carcinoma (CRC) and 60 polyp patients, respectively. After centrifugation, serum (2 μL) was loaded onto the tip of conductive polymer to form a dried serum spot. When the 5 μL methanol-water (1:1, v/v) extraction solvent was spiked onto the dried serum spot followed with +4.5 kV high voltage applied on the polymer tip, the extracted components will be ionized and carried into the MS system for direct metabolic profiling.

FINDINGS

There were 51 metabolites discovered to be significantly changed in CRC serum compared to polyps. Combining these metabolites as the characteristic panel, the ideal diagnostic performance was achieved by Lasso regression model with the accuracy of 88.3%.

INTERPRETATION

This pilot study demonstrated the potential of CPSI-MS as a cost-effective tool in large-scale CRC screening in the high-risk population.

Ni0.5Zn0.5Fe2O4 nanoparticles-decorated poly (vinyl alcohol) nanofiber as resonance light scattering probe for determination of sunitinib in serum samples

Nickel zinc ferrite (Ni_0.5Zn_0.5Fe₂O₄) nanoparticles decorated poly (vinyl alcohol) was constructed by the electrospinning method and used for determining the sunitinib amount in real sample. In this study, resonance light scattering (RLS) technique was used for studying the interaction of nanofibers with sunitinib. Similar Ni_0.5Zn_0.5Fe₂O₄ nanoparticles-decorated nanofibers with average diameter of 200 nm and length up to several millimeters were prepared. The morphology and microstructure of the as prepared Ni _0.5Zn _0.5Fe₂O₄ nanoparticles-decorated nanofibers were studied in details. The nanofibers were characterized by energy dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. The nanofibers are formed through assembling magnetic nanoparticles with poly (vinyl alcohol) as the structure-directing template. Under the optimal conditions, the linear dynamic range and RSD were 5.0 × 10^-3-10.0 mg L^-1 and 1.62% (n = 3), respectively. A limit of detection of 1.0 × 10^-3 mg L^-1 sunitinib was obtained from this method. The obtained results showed successful application of the method for the analysis of sunitinib in real samples.

Coulometry-assisted quantitation in spray ionization mass spectrometry

The concentration of target analyte in a mixture can be quantified by combining coulometric measurements with spray ionization mass spectrometry. A three-electrode system screen printed on the polymer support acts both as the coulometry platform for electrochemical oxidation and the sample loading tip for spray ionization. After loading a droplet of the analyte solution onto the tip, two steps were taken to implement quantitation. First, the electrochemical oxidation potential was optimized with cyclic voltammetry followed by coulometric measurements to calculate the amount of oxidized analyte under a constant low voltage within a fixed period of time (5 s). Then, a high voltage (+4.5 kV) was applied to the tip to trigger spray ionization for measuring the oxidation yield from the native analyte ion and its oxidized product ion intensities by mass spectrometry. The analyte's native concentration is quantified by dividing the oxidized product's concentration (based on Coulomb's law) and the oxidation yield (estimated from mass spectrometry [MS] assuming that the parent and oxidation product have nearly the same ionization efficiencies). The workflow has an advantage in being free of any standard for constructing the quantitation curve. Several model compounds (tyrosine, dopamine, and angiotensin II) were selected for method validation. It was demonstrated that this strategy was feasible with an accuracy of ~15% for a wide coverage of different species including endogenous metabolites and peptides. As an example of its possible practical use, it was initially employed to make a bilirubin assay in urine.

Paper spray ionization mass spectrometry: recent advances and clinical applications

INTRODUCTION

Paper spray mass spectrometry has provided a rapid, quantitative ambient ionization method for xenobiotic and biomolecule analysis. As an alternative to traditional sample preparation and chromatography, paper spray demonstrates the sampling ionization of a wide range of molecules and significant sensitivity from complex biofluids. The amenability of paper spray with dried blood spots and other sampling types shows strong potential for rapid, point-of-care (POC) analysis without time-consuming separation procedures. Areas covered: This special report summarizes the current state and advances in paper spray mass spectrometry that relate to its applicability for clinical analysis. It also provides our perspectives on the future development of paper spray mass spectrometry and its potential roles in clinical settings. Expert commentary: Paper spray has provided the fundamental aspects of ambient ionization needed for implementation at the POC. With further clinical management and standardization, paper spray has the potential to replace traditional complex analysis procedure for rapid quantitative detection of illicit drugs, therapeutic drugs and metabolites. Surface and substrate modifications also offer significant improvement in desorption and ionization efficiencies, resulting in enhanced sensitivity. Comprehensive analysis of metabolites and lipids will further extend the implementation of paper spray ionization mass spectrometry into clinical applications.

Electrospray Modifications for Advancing Mass Spectrometric Analysis

Generation of analyte ions in gas phase is a primary requirement for mass spectrometric analysis. One of the ionization techniques that can be used to generate gas phase ions is electrospray ionization (ESI). ESI is a soft ionization method that can be used to analyze analytes ranging from small organics to large biomolecules. Numerous ionization techniques derived from ESI have been reported in the past two decades. These ion sources are aimed to achieve simplicity and ease of operation. Many of these ionization methods allow the flexibility for elimination or minimization of sample preparation steps prior to mass spectrometric analysis. Such ion sources have opened up new possibilities for taking scientific challenges, which might be limited by the conventional ESI technique. Thus, the number of ESI variants continues to increase. This review provides an overview of ionization techniques based on the use of electrospray reported in recent years. Also, a brief discussion on the instrumentation, underlying processes, and selected applications is also presented.

Highly fluorescent nitrogen-doped graphene quantum dots as a green, economical and facile sensor for the determination of sunitinib in real samples

The preparation of nitrogen-doped graphene quantum dots (N-GQDs), by a simple and inexpensive synthetic procedure, is reported with blue emission and a high quantum yield of 78%.

Discovery bioanalysis and in vivo pharmacology as an integrated process: a case study in oncology drug discovery

Background: A bioanalytical team dedicated to in vivo pharmacology was set up to accelerate the selection and characterization of compounds to be evaluated in animal models in oncology. Results: A DBS-based serial microsampling procedure was optimized from sample collection to extraction to obtain a generic procedure. UHPLC–high-resolution mass spectrometer configuration allowed for fast quantitative and qualitative analysis. Using an optimized lead compound, we show how bioanalysis supported in vivo pharmacology by generating blood and tumor exposure, drug monitoring and PK/PD data. Conclusion: This process provided unique opportunities for the characterization of drug properties, selection and assessment of compounds in animal models and to support and expedite proof-of-concept studies in oncology.

Ionization Suppression and Recovery in Direct Biofluid Analysis Using Paper Spray Mass Spectrometry

Paper spray mass spectrometry is a method for the direct analysis of biofluid samples in which extraction of analytes from dried biofluid spots and electrospray ionization occur from the paper on which the dried sample is stored. We examined matrix effects in the analysis of small molecule drugs from urine, plasma, and whole blood. The general method was to spike stable isotope labeled analogs of each analyte into the spray solvent, while the analyte itself was in the dried biofluid. Intensity of the labeled analog is proportional to ionization efficiency, whereas the ratio of the analyte intensity to the labeled analog in the spray solvent is proportional to recovery. Ion suppression and recovery were found to be compound- and matrix-dependent. Highest levels of ion suppression were obtained for poor ionizers (e.g., analytes lacking basic aliphatic amine groups) in urine and approached -90%. Ion suppression was much lower or even absent for good ionizers (analytes with aliphatic amines) in dried blood spots. Recovery was generally highest in urine and lowest in blood. We also examined the effect of two experimental parameters on ion suppression and recovery: the spray solvent and the sample position (how far away from the paper tip the dried sample was spotted). Finally, the change in ion suppression and analyte elution as a function of time was examined by carrying out a paper spray analysis of dried plasma spots for 5 min by continually replenishing the spray solvent. Graphical Abstract ᅟ.

Analysis of biofluids by paper spray MS: advances and challenges

Paper spray MS is part of a cohort of ambient ionization or direct analysis methods that seek to analyze complex samples without prior sample preparation. Extraction and electrospray ionization occur directly from the paper substrate upon which a dried matrix spot is stored. Paper spray MS is capable of detecting drugs directly from dried blood, plasma and urine spots at the low ng/ml to pg/ml levels without sample preparation. No front end separation is performed, so MS/MS or high-resolution MS is required. Here, we discuss paper spray methodology, give a comprehensive literature review of the use of paper spray MS for bioanalysis, discuss technological advancements and variations on this technique and discuss some of its limitations.

Ambient Ionization Mass Spectrometry for Point-of-Care Diagnostics and Other Clinical Measurements

BACKGROUND

One driving motivation in the development of point-of-care (POC) diagnostics is to conveniently and immediately provide information upon which healthcare decisions can be based, while the patient is on site. Ambient ionization mass spectrometry (MS) allows direct chemical analysis of unmodified and complex biological samples. This suite of ionization techniques was introduced a decade ago and now includes a number of techniques, all seeking to minimize or eliminate sample preparation. Such approaches provide new opportunities for POC diagnostics and rapid measurements of exogenous and endogenous molecules (e.g., drugs, proteins, hormones) in small volumes of biological samples, especially when coupled with miniature mass spectrometers.

CONTENT

Ambient MS-based techniques are applied in diverse fields such as forensics, pharmaceutical development, reaction monitoring, and food analysis. Clinical applications of ambient MS are at an early stage but show promise for POC diagnostics. This review provides a brief overview of various ambient ionization techniques providing background, examples of applications, and the current state of translation to clinical practice. The primary focus is on paper spray (PS) ionization, which allows quantification of analytes in complex biofluids. Current developments in the miniaturization of mass spectrometers are discussed.

SUMMARY

Ambient ionization MS is an emerging technology in analytical and clinical chemistry. With appropriate MS instrumentation and user-friendly interfaces for automated analysis, ambient ionization techniques can provide quantitative POC measurements. Most significantly, the implementation of PS could improve the quality and lower the cost of POC testing in a variety of clinical settings.

Ambient ionization MS for bioanalysis: recent developments and challenges

Ambient ionization MS has become very popular in analytical science and has now evolved as an effective analytical tool in metabolomics, biological tissue imaging, protein and small molecule drug analysis, where biological samples are probed in a rapid and direct fashion with minimal sample preparation at ambient conditions. However, certain inherent challenges continue to hinder the vibrant prospects of these methods for in situ analyses or to replace conventional methods in bioanalysis. This review provides an introduction to the field and its application in bioanalysis, with an emphasis on the most recent developments and applications. Furthermore, ongoing challenges or limitations related to quantitation, sensitivity, selectivity, instrumentation and mass range of these ambient methods will also be discussed.