Steady-state Fluorescence Microscopy Research Articles

Proline-Modified UIO-66 as Nanocarriers to Enhance Candida rugosa Lipase Catalytic Activity and Stability for Electrochemical Detection of Nitrofen.

Immobilization can be used to improve the stability of lipases and enhances lipase recovery and reusability, which increases its commercial value and industrial applications. Nevertheless, immobilization frequently causes conformational changes of the lipases, which decrease lipase catalytic activity. in the present work, we synthesized UIO-66 and grafted UIO-66 crystals with proline for immobilization of Candida rugosa lipase (CRL). As indicated by steady-state fluorescence microscopy, grafting of proline onto UIO-66 crystals induced beneficial conformational change in CRL. CRL immobilized on UIO-66/Pro (CRL@UIO-66/Pro) demonstrated higher enzyme activity and better recyclability than that immobilized on UIO-66 (CRL@UIO-66) in both hydrolysis (CRL@UIO-66/Pro: 0.34 U; CRL@UIO-66: 0.15 U) and transesterification (CRL@UIO-66/Pro: 0.93 U; CRL@UIO-66: 0.25 U) reactions. The higher values of kcat and kcat/Km of CRL@UIO-66/Pro also showed that it had better catalytic efficiency as compared to CRL@UIO-66. It is also worth noting that CRL@UIO-66/Pro (0.93 U) demonstrated a much higher transesterification activity as compared to free CRL (0.11 U), indicating that UIO-66/Pro has increased the solvent stability of CRL. Both CRL@UIO-66 and CRL@UIO-66/Pro were also used for the fabrication of biosensors for nitrofen with a wide linear range (0-100 μM), lower limit of detection, and good recovery rate.

Analyzing Liposomal Drug Delivery Systems in Three-Dimensional Cell Culture Models Using MALDI Imaging Mass Spectrometry.

Cancer chemotherapeutics often fail to reach all diseased cells. To help solve this problem, researchers are investigating novel drug delivery systems. Liposomes are an attractive option due to their low toxicity, high biocompatibility, and potential to carry a large amount of a drug to the tumor site, all while avoiding being eliminated from the body. This study evaluates the penetration of doxorubicin-encased liposomes into three-dimensional cell cultures, or spheroids. Liposomes composed of lipids containing head groups of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cholesterol were created by extrusion. Doxorubicin is encapsulated within the hydrophilic core of the liposome. The drug is actively released in the spheroid as the lipids bind to cellular lipid bilayers. Spheroids were dosed with liposomal doxorubicin, free doxorubicin, or media control to assess drug distribution over the course of 72 h. Drug penetration was visualized by Matrix-Assisted Laser Desorption/Ionization-Imaging Mass Spectrometry (MALDI-IMS) with confirmation by steady state fluorescence microscopy, creating a comprehensive picture of drug distribution. This technique is able to identify both free and liposomal doxorubicin throughout the spheroid after just 12 hours of treatment. Additionally, MALDI-IMS is able to detect three metabolites of doxorubicin, indicating that cells actively metabolize the drug during treatment. Steady state fluorescence microscopy cannot distinguish the drug from its metabolites as they have the same emission spectra. This report summarizes the first study to use MALDI-IMS to analyze drug penetration of a liposomal drug carrier as well as its metabolites.

Synthesis and Properties of Alkyl Dibenzyl Ether Quaternary Ammonium Gemini Surfactant

Abstract Three gemini surfactants with dibenzyl ether spacer (10-B-10, 12-B-12, and 14-B-14) were synthesized and characterized. The surface activity and thermodynamic properties of micellization were determined by surface tension, steady-state fluorescence microscopy, and conductivity methods. The thermodynamic parameters of micellization (ΔmicG0, ΔmicH0, and ΔmicS0) derived from the electrical conductivity measurement implied that the micellization of these surfactants was driven by enthalpy. The enthalpy–entropy compensation of micellization showed that the stability of micelles increased with increasing alkyl chain length. Finally, we evaluated the effects of alkyl chain length on the interfacial tension, foam ability, and the emulsion stability.