Dual-mode colorimetric and fluorescence sensing system for the detection of captopril based on Fe/NC nanozymes and carbon dots

A lysosome-targeted fluorescent probe for thiol detection in drug analysis and multiple biological systems

Biothiols, characterized by their unique sulfhydryl (-SH) groups, possess excellent antioxidant properties, effectively neutralizing the damage to cellular structures caused by reactive oxygen species (ROS) in living organisms. Additionally, lysosomes play a crucial role in decomposing damaged biomolecules through the action of their internal enzymes, regulating the cellular redox state, and mitigating oxidative stress. To facilitate rapid monitoring of intracellular biothiols, particularly within lysosomes, we constructed a lysosome-targeted biothiol fluorescent probe, PHL-DNP, in this study. PHL-DNP exhibited excellent photophysical properties in an aqueous test system, including strong fluorescence enhancement response, excellent selectivity, and low detection limits (Cys 16.5 nM, Hcy 16.8 nM, GSH 21.3 nM, Cap 26.6 nM). These attributes enabled easy and efficient qualification of Cys on test strips and accurate determination of the effective content of captopril tablets. Notably, PHL-DNP demonstrated low cytotoxicity and precise lysosomal targeting. Through bioimaging, PHL-DNP not only monitored changes in biothiol levels under oxidative stress but also assessed biothiols in complex biological systems such as live HeLa cells, zebrafish, tumor tissue sections, and radish roots. This provides a promising tool for quantitative analysis of biothiols, disease marker detection, and drug testing.

A novel robust hydrogel-assisted paper-based sensor based on fluorescence UiO-66-NH2@ZIF-8 for the dual-channel detection of captopril

Captopril (CP) is commonly used as an active enzyme inhibitor for the treatment of coronary heart disease, hypertension and angina pectoris. The development of sensitive and efficient method for CP analysis is of great importance in biomedical research. Herein, we fabricated a sensitive and robust hydrogel-assisted paper-based sensor based on fluorescence UiO-66-NH2@ZIF-8 and Co, N-doped carbon nanozymes with oxidase-mimicking activity for accurate monitoring of captopril. The hydrogel-assisted paper-based sensor appeared a visible pink signal due to the catalytic oxidation of colorless N,N-diethyl-p-phenylenediamine (DPD) to oxDPD by Co, N-doped carbon-based nanozymes, and resulted in the fluorescence quenching of UiO-66-NH2@ZIF-8. In the presence of captopril, the oxidation of chromogenic substrate DPD by Co, N-doped nanozymes in the hydrogel-assisted paper-based sensor was hindered and accompanied by a change in the visible color, leading to recovery of the fluorescence of UiO-66-NH2@ZIF-8, and the change in the fluorescence color could also be observed. Therefore, the quantitative detection of captopril is achieved by taking a smartphone photograph and converting the image parameters into data information using ImageJ software. The portable hydrogel-assisted paper sensor provided sensitive detection of captopril in two modes based on visible color change as well as fluorescence color change with limits of detection of 0.45 μM and 0.47 μM, respectively. This hydrogel-assisted paper-based sensor has been successfully applied to the accurate monitoring of captopril in human serum, providing a potential avenue for in situ detection of captopril.

Implications of analytical nanoscience in pharmaceutical and biomedical fields: A critical view

This review summarizes recent progress performed in the design and application of analytical tools and methodologies using nanomaterials for pharmaceutical analysis, and specifically new nanomedicines at distinct phases of development and translation from preclinical to clinical stages. Over the last 10-15 years, a growing number of studies have utilized various nanomaterials, including carbon-based, metallic nanoparticles, polymeric nanomaterials, materials based on biological molecules, and composite nanomaterials as tools for improving the analysis of pharmaceutical products. New and more complex nanomaterials are currently being explored to influence different stages of the analytical process. These materials provide unique properties to support the extraction of analytes in complex samples, increase the selectivity and efficiency of chromatographic separations, and improve the analytical properties of many sensor applications. Indeed, nanomaterials, including electrochemical detection approaches and biosensing, are expanding at a remarkable rate. Furthermore, the analytical performance of numerous approaches to determine drugs in different matrices can be significantly improved in terms of precision, detection limits, selectivity, and time of analysis. However, the quality control and metrological characterization of the currently synthesized nanomaterials still depend on the development of new and improved analytical methodologies, and the application of specific and improved instrumentation. Therefore, there is still much to explore about the properties of nanomaterials which need to be determined even more precisely and accurately.

Development of a "turn off" fluorescent molecularly imprinted nanoparticle-based sensor for selective captopril quantification in synthetic urine and wastewater samples

The combination of silica nanoparticles with fluorescent molecularly imprinted polymers (Si-FMIPs) prepared by a one-pot sol-gel synthesis method to act as chemical sensors for the selective and sensitive determination of captopril is described. Several analytical parameters were optimized, including reagent ratio, solvent, concentration of Si-FMIP solutions, and contact time. Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and the ninhydrin assay were used for characterization. The selectivity was evaluated against molecules belonging to other drug classes, such as fluoroquinolones, nonacid nonopioids, benzothiadiazine, alpha amino acids, and nitroimidazoles. Under optimized conditions, the Si-FMIP-based sensor exhibited a working range of 1-15 µM, with a limit of detection (LOD) of 0.7 µM, repeatability of 6.4% (n = 10), and suitable recovery values at three concentration levels (98.5% (1.5 µM), 99.9% (3.5 µM), and 99.2% (7.5 µM)) for wastewater samples. The sensor provided a working range of 0.5-15 µM for synthetic urine samples, with an LOD of 0.4 µM and a repeatability of 7.4% (n = 10) and recovery values of 93.7%, 92.9%, and 98.0% for 1.0 µM, 3.5 µM, and 10 µM, respectively. In conclusion, our single-vessel synthesis approach for Si-FMIPs proved to be highly effective for the selective determination of captopril in wastewater and synthetic urine samples.

Dual-mode fluorescence and colorimetric sensing of sulfide anion in natural water based on near-infrared Ag2S quantum dots and MnO2 nanosheets complex

Near infrared (NIR) emission Ag2S quantum dots (QDs) are of great value for biochemical sensing with strong anti-interference and low toxicity. Herein, NIR fluorescence Ag2S QDs were synthesized successfully. Combined with the excellent oxidase-like characteristics of manganese dioxide (MnO2) nanosheets, a fluorescence and colorimetric dual-mode sensor for sulfide anion was developed. MnO2 nanosheets could effectively catalyze the oxidation of TMB to produce blue TMB oxide (ox TMB), at the same time, the fluorescence of Ag2S QDs could be effectively quenched by fluorescence internal filtration effect (IFE) and dynamic quenching effect. The enzyme-like activity was weakened and the NIR fluorescence of Ag2S QDs was restored when sulfide anion (S2-) was added, due to the reduction of MnO2 to Mn2+.The linear ranges for fluorescence and colorimetric analysis of S2- were 2-250 μM and 0.3-50 μM, with detection limits of 0.6 and 0.215 μM, correspondingly. The dual-mode sensor had a wider detection range, higher sensitivity and shorter reaction time, which could be used for highly selective detection of S2- in different concentration ranges. In addition, it had been successfully applied to the determination of sulfide in water samples with satisfactory accuracy and sensitivity.

A colorimetric/electrochemical sensor based on coral-like CuCo2O4@AuNPs composites for sensitive dopamine detection

As a central neurotransmitter, DA (dopamine) plays a vital part in human metabolism, and its accurate detection is of great significance in disease diagnosis. In this work, we used Cu/Co bimetallic metal-organic frameworks (MOFs) as templates and gold nanoparticles (AuNPs) to construct novel nanocomposite coral-like CuCo2O4@AuNPs with strong peroxidase activity and electrochemical response. The coral-like CuCo2O4@AuNPs showed excellent peroxidase activity, and the Km value was as low as 0.358 mM. In the presence of H2O2, the colorless substrate 3,3',5,5', -tetramethylbenzidine (TMB) can be catalytically oxidized into a blue product. Simultaneously, coral-like CuCo2O4@AuNPs, as an electroactive substance, possess strong electrocatalytic activity, which enhances the electron-transfer rate and promotes excellent current response. In the presence of DA, coral-like CuCo2O4@AuNPs can catalyze the oxidation of DA to dopaquinone, which further enhances the electrochemical signal. In addition, DA captures hydroxyl radicals and inhibits the oxidation of TMB, resulting in an obvious color change (blue turns colorless) and realizing colorimetric detection with the naked eye. On this basis, we successfully established a dual-mode colorimetric/electrochemical sensor using coral-like CuCo2O4@AuNP nanocomposites as a dual-signal probe. Combining colorimetric and electrochemical detection, the sensor achieved a wide linear range (0-1 mM) and a low detection limit (0.07 μM) for DA concentration. It was also successfully used for the detection of DA in human serum and urine with good results. In summary, this work provides an intuitive, economical, sensitive, and promising platform for DA detection.

Recent advances in the colorimetric and fluorescence analysis of bioactive small-molecule compounds based on the enzyme-like activity of nanomaterials

Nanomaterials with enzyme-like activity have been widely used in the construction of colorimetric and fluorescence sensors due to their advantages of cost-effectiveness, high stability, good biocompatibility, and ease of modification. Furthermore, the colorimetric and fluorescence sensors, which are effective approaches for detecting bioactive small-molecule compounds, have been extensively explored due to their simple operation and high sensitivity. Recent significant researches have focused on designing various sensors based on nanozymes with peroxidase- and oxidase-like activity for the colorimetric and fluorescence analysis of different analytes. In this review, recent developments (from 2018 to present) in the colorimetric and fluorescent analysis of bioactive small-molecule compounds based on the enzyme-like activity of nanomaterials were summarized. In addition, the challenges and design strategies in developing colorimetric and fluorescent assays with high performance and specific sensing were discussed.

LC-MS/MS bioanalytical method for the quantitative analysis of nifedipine, bisoprolol, and captopril in human plasma: Application to pharmacokinetic studies

In this study, the development and validation of an accurate and highly sensitive LC-MS/MS method were performed for the estimation of nifedipine, bisoprolol and captopril in real human plasma. Liquid-liquid extraction using tert-butyl methyl ether was efficiently applied for extraction of the analytes from plasma samples. The chromatographic separation was carried out using an isocratic elution mode on the X-terra MS C18 column (4.6 × 50 mm, 3.5 μm). The mobile phase consisted of methanol-0.1% formic acid (95:5, v/v) for determination of nifedipine and bisoprolol and acetonitrile-0.1% formic acid (70:30, v/v) for determination of captopril with a flow rate of 0.5 ml/min. Acceptable results regarding the different validation characteristics of the analytes were obtained in accordance with US Food and Drug Administration recommendations for bioanalytical methods. The developed approach was linear over concentration ranges of 0.5-130.0, 50.0-4,500.0 and 0.3-30.0 ng/ml for nifedipine, captopril and bisoprolol, respectively. The method revealed a sufficient lower limit of quantification in the range of 0.3-50.0 ng/ml, as well as high recovery percentages, indicating high bioanalytical applicability. The proposed method was efficiently applied to a pharmacokinetic evaluation of a fixed-dose combination of the analytes in healthy male volunteers.