Application of Different Zeolites for Improvement of the Characteristics of a pH‐FET Biosensor Based on Immobilized Urease

Different modifications of the zeolites Na⁺‐Beta and LTA were applied for improving the working characteristics of a urea biosensor. The bioselective membrane of the biosensor was based on urease and different zeolites co‐immobilized with bovine serum albumin on the surface of a pH‐FET. It was shown that the biosensors modified with the zeolites H⁺‐Beta30 and H⁺‐Beta50 are characterized by increased sensitivity to urea. The influence of the zeolite concentration on the sensitivity of the biosensors was studied. The optimal concentration of the zeolites H⁺‐Beta30 and H⁺‐Beta50 in the bioselective membrane was 15 %. Different variants of co‐immobilization of urease and zeolite H⁺‐Beta30 were studied and the optimal method was selected. Thus, a general conclusion is that the urea biosensor sensitivity can be improved using zeolite H⁺‐Beta30 for urease immobilization in the bioselective membrane.     

Polypeptide/Doxorubicin Hydrochloride Polymersomes Prepared Through Organic Solvent‐free Technique as a Smart Drug Delivery Platform

Rapid and efficient side‐chain functionalization of polypeptide with neighboring carboxylgroups is achieved via the combination of ring‐opening polymerization and subsequent thiol‐yne click chemistry. The spontaneous formation of polymersomes with uniform size is found to occur in aqueous medium via electrostatic interaction between the anionic polypeptide and cationic doxorubicin hydrochloride (DOX·HCl). The polymersomes are taken up by A549 cells via endocytosis, with a slightly lower cytotoxicity compared with free DOX ·HCl. Moreover, the drug‐loaded polymersomes exhibit the enhanced therapeutic efficacy, increase apoptosis in tumor tissues, and reduce systemic toxicity in nude mice bearing A549 lung cancer xenograft, in comparison with free DOX ·HCl.     

Fluorescent azophenol-quinazoline dyad as multichannel reversible pH indicator in aqueous media: an innovative concept on diazo based dyads

A novel azophenol-quinazoline dyad 1 has been designed, synthesized and demonstrated as an efficient reversible multichannel pH indicator through distinct signalling in aqueous media. Owing to the competence between highly fluorescent quinazoline moiety and a well known fluorescence quencher diazo group, dyad 1 is moderately fluorescent in nature. Under acidic conditions 1 displays diverse fluorogenic changes (blue emission at pH 4.25; green at pH 1.80) while under basic condition (pH 11.80) chromogenic changes were observed.     

THE USE OF CARBOXYMETHYL ETHOXYLATE SURFACTANT TO DISSOLVE VITAMIN K1 AND TO OBTAIN LOW INTERFACIAL TENSION AND STABLE EMULSION SYSTEMS

Abstract

The presence of vitamin K₁ in human body is important for preventing the hemorrhagic disease. Due to its very long side chain, vitamin K₁ is highly insoluble in water. We have successfully dissolve a substantial amount of vitamin K₁ in solutions of a commercial surfactant containing carboxymethyl ethoxylates (Hüls B433) and obtained low interfacial tension (IFT) and stable emulsion systems. This paper will present the details of these experiments. The solubilization of vitamin K₁ was estimated from UV absorption. The IFT values were measured by using a spinning drop apparatus and all particle sizes were determined by using laser light scattering. By using the Hüls B433 surfactant and an optimum amount of CaCl₂, we can dissolve vitamin K₁ in water and obtain low IFT systems in the order of 10^?2 dyne/cm. The emulsions obtained in these systems are stable and contain droplet sizes below 65 nm. The dissolution of vitamin K₁ and the IFT behavior in these systems follow the rules for crude oil and prefer larger surfactant micelles.     

Spectrophotometric Studies of Entrapped Thymol Phtalein pH Indicator into Sol‐Gel Matrix

This research involves the behavior of thymol phtalein pH indicator entrapped into the sol‐gel derived inorganic matrix. The method is based on the physical entrapment of the reagent molecules in the sol‐gel matrix. The immobilized thymol phthalein pH indicator shows behavior similar to its solution counterpart. The UV/vis spectra indicate that the thymol phthalein retains its structure during the sol‐gel reactions in terms of response to pH. Thymol phthalein can be regarded as uniformly distributed in the sol‐gel matrix. This observation has been confirmed using polarized microscopy. This research shows that thymol phtalein can be immobilized in sol‐gel glasses and used as a solid pH sensor.     

Encapsulation of Phenolphthalein pH-Indicator into a Sol-Gel Matrix

Transparent monolithic silica doping with phenolphthalein has been prepared via the acid-catalyzed sol-gel reactions of tetraethylorthosilicate in the presence of phenolphthalein. The immobilized phenolphthalein pH-indicator shows similar behavior as its solution counterpart. The UV/Vis spectra indicate that the phenolphthalein retains its structure during the sol-gel reactions in terms of response to pH. The phenolphthalein can be regarded as uniformly distributed in the silica matrix. This observation has been confirmed using polarized microscopy.