The quantitative determination of nucleic acids is of great importance in fundamental research and clinical diagnosis. In this work, the interaction between DNA and cationic Gemini surfactant 12-4-12, which changes the conformation of DNA, was investigated by UV-vis absorption, FT-IR spectra and steady-state fluorescence techniques. A hydrophobic pyrene probe was used to investigate the microenvironment change and calculate the critical micelle concentration (CMC) of Gemini surfactant 12-4-12 (0.69 mmol/L), which is close to the value obtained from the conductivity method (0.79 mmol/L). A new detection assay for DNA is proposed with Gemini surfactant 12-4-12, using the resonance light-scattering (RLS) technique. The formation of DNA-12-4-12 complex resulted in enhanced RLS signals at 368 nm, which is proportional to DNA concentration in the range 0.304-5.32 mg/L, with a detection limit of 35 µg/L. Most coexisting substances do not interfere in the detection and four synthetic samples were analyzed satisfactorily.
The present work aims to propose a new simple assay for deoxyribonucleic acids (DNA) by applying cationic Gemini surfactant 12-3-12 and cationic dye methylene blue (MB) as resonance light scattering (RLS) probes. The formation of MB-DNA-12-3-12 complex at pH 3.99 results in enhanced RLS signals at 369 nm, which is proportional to the concentration of DNA from 0 to 0.88 mg L À1 , with determination limit of 0.014 mg L À1 . Most foreign substances do not interfere in the detection and three synthetic samples are analyzed satisfactorily. transmission electron microscopy (TEM), FTIR, and ultraviolet spectra are used to investigate the interaction mechanism.
Polymer (N,N-dimethyl-ethylamine methacrylate)-block-poly{6-[4-(4-methoxy phenyl-azo) phenoxy] hexylacrylate} p(DMAEMA m -b-AZOM n ) was synthesized by successive reversible addition-fragmentation chain transfer polymerization in the hydrothermal reactor. The products were characterized by hydrogen nuclear magnetic resonance, differential scanning calorimetry, gel permeation chromatography, and ultraviolet and visible absorption spectroscopy (UV-vis). In H 2 O/THF mixture, we found amphiphilic p(DMAEMA m -b-AZOM n ) self-assembles occurred. p(DMAEMA 79 -b-AZOM 7 ) self-assembled into rods, p(DMAEMA 79 -b-AZOM 5 ) self-assembled into giant microspheres with rods wind around, p(DMAEMA 79 -b-AZOM 2 ) self-assembled into microspheres. Photochromic behaviors of the polymers in different environments were investigated. We found the colors of diblock copolymers in films changed from yellow to orange after irradiation by ultraviolet and visible (UV) light. The rates of trans-cis photoisomerization in films were almost the same for the three p(DMAEMA m -b-AZOM n ) copolymers. The rates in aqueous micellar solutions were only marginally faster than those in films for all the three diblock copolymers. The observation of a sizable rate difference in different environments for p(DMAEMA m -b-AZOM n ) suggested that a rotational mechanism might be operative for these water-soluble amphiphilic diblock copolymers. The self-assembly behaviors of three copolymers and the application of p(DMAEMA 79 -b-AZOM 2 ) microspheres in biochemistry were investigated in present work.
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