Impact of temperature on the binding interaction between dsDNA and curcumin: An electrochemical study.

In this study, we investigated the binding mode between double-stranded deoxyribonucleic acid (dsDNA) and curcumin (CU) using differential pulse voltammetry (DPV), UV-Vis spectroscopy, and molecular docking. By employing these techniques, we predicted the binding within the minor groove region of dsDNA and CU. Significantly, we employed electrochemistry, specifically cyclic voltammetry (CV), to explore the temperature effect on the dsDNA and CU binding. To the best of our knowledge, this is the first study to utilize electrochemical methods for investigating the temperature-dependent behavior of this binding interaction. Our findings revealed temperature-dependent variations in the binding constants: 2.42 × 103 M-1 at 25 °C, 4.26 × 103 M-1 at 30 °C, 5.44 × 103 M-1 at 35 °C, 6.29 × 103 M-1 at 40 °C, and 7.52 × 103 M-1 at 45 °C. Notably, the binding constant exhibited an increasing trend with elevated temperatures, indicating a temperature-dependent enhancement of the binding interaction.

Development of an eco-friendly fluorescence nanosensor based on molecularly imprinted polymer on silica-carbon quantum dot for the rapid indoxacarb detection.

Rapid and efficient detection of indoxacarb (IXC), a common chemical contaminant, in environmental and biological samples is necessary. In this work, a modern optical sensor was developed for IXC, based on environmentally friendly molecularly imprinted polymer (MIP) coated on silica-carbon quantum dots (SiCQDs). A hydrothermal method was used to prepare highly fluorescence SiCQDs and, subsequently, MIP formed on surface (MIP@SiCQDs) using a sol-gel method. A linear relationship between the fluorescence quenching effect and increased IXC concentration was found for the range of 4-102 nM, under the optimal conditions, with a 1 nM detection limit. Precisions was of 4.5 and 2.3% for five replicate detections at 21 and 60 nM IXC, respectively. Applicability of the sensor for IXC quantification in environmental and biological samples was verified with recoveries in the range 95-106% with a relative standard deviation of <6.0%.

Ingenious pH-sensitive etoposide loaded folic acid decorated mesoporous silica-carbon dot with carboxymethyl-ßcyclodextrin gatekeeper for targeted drug delivery and imaging.

A new strategy is reported for the synthesis of label-free fluorescent mesoporous silica (MS) by the introduction of fluorescent carbon dots in the MSs (MSCDs) in this work. Etoposide (ETO) loaded MSCDs have been used as a drug model. Carboxymethyl ß-cyclodextrin (CßCD) used as a gatekeeper agent was attached to amine-functionalized MSCDs to retain ETO molecules inside the nanocarrier. In order to target the nanocarrier to the site of action, folic acid (FA) was grafted onto the MSCDs surface (FA-CßCD-MSCDs). The in vitro release of an entrapped ETO from the formulation in phosphate buffered saline (PBS) (pH 7.4) and citrate buffer (pH 5.4) was investigated. At neutral pH in PBS, the pores are blocked by CßCD which prevent premature ETO release. However, under the weakly acidic intercellular environment of the tumor, the amide bond can be partially hydrolyzed and consequently lead to the ETO release from the nanocarrier. The targeted and ETO-loaded FA-CßCD-MSCDs showed a higher growth inhibition towards FA-positive HeLa cells compared with FA-negative HepG2 cells, as demonstrated by comparison of in vitro cytotoxicity experiments. In addition, the CDs emission was used for the fluorescent microscopic imaging. Moreover, molecular docking and molecular dynamics simulations (MDS) were applied to examine the interactions of ETO molecules with the topoisomerase II (Top II). ETO molecules bind Top II with overall binding constants of 3.08 × 1010 M-1, according to docking results. Based on MDS results, ETO-Top II complex is formed through hydrophobic interactions.

Aptasensor based on fluorescence resonance energy transfer for the analysis of adenosine in urine samples of lung cancer patients.

A new aptasensor was designed for the analysis of adenosine based on fluorescence resonance energy transfer (FRET) between CdS quantum dot (QDs) as a donor and polypyrrole (Ppy) as an acceptor. The QDs were covalently bonded to anti-adenosine aptamer where its fluorescence was quenched by Ppy. When Ppy was replaced by adenosine, the fluorescence of QDs was restored and its intensity was proportional to the adenosine concentration. Under the optimized conditions, a linear range was found to be 23-146 nM with a detection limit of 9.3 nM. The method was used for analysis of adenosine in urine samples of lung cancer patients and its accuracy was evaluated by comparison of the results of the proposed method with the standard method of HPLC-UV. Furthermore, the interactions of adenosine molecules with the aptamer were investigated using molecular modeling, including molecular dynamic simulations (MDS). The results demonstrated that each G-quadruplex aptamer can capture two adenosine molecules.