Structure Of Polyethylenimine Research Articles

Surface modification strategy of boronic acids on glass substrates and its application for detecting glycated hemoglobin by liquid crystal-based sensors

Surface modification is a fundamental technique in the development of chemical sensors and biosensors. In this work, we established a strategy to incorporate boronic acids into the structure of polyethylenimine (PEI) through a multi-component reaction under microwave conditions. The presence of boronic acids on PEI was identified by NMR and IR spectroscopy. This borylated PEI polymer was coated on the glass substrate and its binding activity was tested by using 5-(diethylamino)-2-((methylimino)methyl)phenol (DAHMI) as a fluorescence tag. Moreover, the boronic acid-modified surface was applied to construct a liquid crystal (LC)-based sensor system for detecting glycated hemoglobin (HbA1C). The specific binding of HbA1C to boronic acid on glass surface lead to the reorientation of LCs, such that a dark-to-bright optical transition was observed under polarized light. Based on this mechanism, the limit of detection of the LC-based sensor for HbA1C was 100 μg/mL with good specificity. Our results demonstrated the applicability of the surface modification strategy of boronic acids on glass substrates for developing chemical sensors and biosensors.

Comparison of different cationic polymers efficacy in fabrication of alginate multilayer microcapsules

In past decades, alginate-based multilayer microcapsules have been given important attention in various pharmaceutical investigations. Alginate-poly l lysine-alginate (APA) is studied the most. Due to the similarity between the structure of polyethyleneimine (PEI) and poly-L-lysine (PLL) and also lower price of PEI than PLL, this study was conducted to compare the efficacy of linear (LPEI) and branch (BPEI) forms of PEI with PLL as covering layers in fabrication of microcapsules. The microcapsules were fabricated using electrostatic bead generator and their shape/size, surface roughness, mechanical strength, and interlayer interactions were also investigated using optical microscopy, AFM, explosion test and FTIR, respectively. Furthermore, cytotoxicity was evaluated by comparing the two anionic final covering layers alginate (Alg) and sodium cellulose sulphate (NCS) using MTT test. BPEI was excluded from the rest of the study due to its less capacity to strengthen the microcapsules and also the aggregation of the resultant alginate-BPEI-alginate microcapsules, while LPEI showed properties similar to PLL. MTT test also showed that NCS has no superiority over Alg as final covering layer. Therefore, it is concluded that, LPEI could be considered as a more cost effective alternative to PLL and a promising subject for future studies.

Phosphorylation of polyethylene imines in chloroform in the presence of calix[4]resorcinarenes

Kinetics of the reaction of alkylated polyethylene imines with 4-nitrophenyl bis(chloromethyl)-phosphinate in chloroform in the absence and in the presence of substituted calix[4]resorcinarenes were studied by UV spectrophotometry. It was shown that calixarenes forming mixed aggregates with polyethylene imines have a catalytic effect on the polymer phosphorylation process. The catalytic effect depends on the structure of polyethylene imine and the component ratio in the system.

Drag reduction and molecular structure. The interaction of polyethylenimine with some linear high polymers

The structure of polyethylenimine in aqueous and ethanolic solutions was investigated by measuring the fluorescence polarization of dansyl conjugates. In aqueous solutions, all polyethylenimines, whatever their molecular weight, are associated into large aggregates containing rotating units having rotary relaxation times corresponding to spherical particles of molecular weight about 3–6 × 103. The interaction of polyethylenimine with very dilute solutions of linear high polymers has been investigated by fluorescence polarization measurements and by the measurement of turbulent drag. Addition of polyethylenimine causes the solutions of anionic polymers to lose their capability of reducing turbulent drag. The results are discussed in relation to the proposed structure of the anionic–cationic complexes formed in the mixtures.