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.

A highly sensitive fluorescence "on-off-on" sensing platform for captopril detection based on AuNCs@ZIF-8 nanocomposite

Here, a novel fluorescent sensing strategy is established for the detection of captopril (CP) sensitively on the basis of a nanocomposite of gold nanoclusters (AuNCs) and metal-organic framework (AuNCs@ZIF-8). The aggregation-induced emission (AIE) effect will be triggered when AuNCs is encapsulated by metal-organic framework (MOF) which served as a carrier since it limits the molecular motion of AuNCs, and the fluorescence of AuNCs greatly enhanced about 5-time after forming the nanocomposites of AuNCs@ZIF-8. The strong orange-emission at 562 nm was quenched in the presence of mercury ions through dynamic quenching. After adding captopril, the quenched fluorescence of AuNCs@ZIF-8/Hg2+ system would be restored due to the specific interaction among captopril with mercury ions. Simultaneously, the restored degree of AuNCs@ZIF-8/Hg2+ fluorescence depended on the concentration of captopril. Hence, with AuNCs@ZIF-8 serving as reporter signal, the captopril content can be monitored by an "on-off-on" fluorescence sensing mode with a linear relationship of 1-100 μM, and the limit of detection for captopril was 0.134 μM.

In silico design and pharmacological evaluation of conjugates of atenolol with modified saccharide for cardiovascular targeting

Amongst a wide range of biological macromolecules, saccharides exhibit the potential to be specifically recognized by cell-surface receptors and hence can be utilized as ligands in targeted drug delivery. The current study aims to use saccharides viz. Galactose, Pectin and Chitosan to improve targeting of Atenolol by oxalyl chloride mediated grafting. Conjugates were engineered by grafting Atenolol, a cardiovascular agent with the modified saccharide units. The conjugates were characterized by FTIR, DSC and ¹H NMR study. Drug release analysis and cellular uptake study was carried out using H9c2 cell lines which represent that concentration of drug in cells treated with all atenolol-saccharide conjugates is enhanced by almost two-folds in comparison with cells treated with atenolol solution. Thus cell line study confers the evidence of selective cardiac delivery. No significant cytotoxicity was observed in case of all synthesized conjugates in the Brine shrimp lethality bioassay. Possible binding of the developed conjugates with the GLUT-4 receptors was assessed by in silico analysis using homology model developed by Swiss Model server. Hence it was concluded that the application of these conjugates with saccharides in selective cardiovascular drug delivery can be a promising approach to increase bioavailability, minimize drug loss by degradation and prevent harmful side effects by increasing specific cell targeting.

Facile Preparation of Boron and Nitrogen Codoped Green Emission Carbon Quantum Dots for Detection of Permanganate and Captopril

A hydrothermal strategy for preparing boron and nitrogen codoped carbon quantum dots was studied using the precursors of p-amino salicylic acid, boric acid and ethylene glycol dimethacrylate. The boron and nitrogen codoped carbon quantum dots have high fluorescence intensity, good monodispersity, high stability, superior water solubility, and a fluorescence quantum yield of 19.6%. Their average size is 5 nm. Their maximum excitation and emission wavelengths are 380 and 520 nm, respectively. Permanganate (MnO₄^-) quenched boron and nitrogen codoped carbon quantum dots fluorescence through inner filter effect and static quenching effects. The linear relation between quenching efficiency and MnO₄^- concentration ranged from 0.05 to 60 μmol/L with a detection limit of 13 nmol/L. In the presence of captopril, MnO₄^- was reduced to Mn²⁺ and the fluorescence of boron and nitrogen codoped carbon quantum dots was recovered. The linear range between recovery and captopril concentration was from 0.1 to 60 μmol/L. The limit of detection was 0.03 μmol/L. The developed method can be employed as a sensitive fluorescence sensing platform for MnO₄^-. It has been successfully used for captopril detection in mouse plasma.