姜黄素-La3+-CTMAB-核酸体系的荧光增强效应及其应用

研究了镧离子(La3+)-姜黄素(CU)-十六烷基三甲基溴化铵(CTMAB)-核酸荧光增强体系.建立了测定核酸的新方法.体系的最优条件为:六次甲基四胺(HMTA)-HCl缓冲溶液(pH 5.80)中,1.00× 10-3 mol/L阳离子表面活性剂CTMAB存在下,姜黄素浓度为2.00×10-5 mol/L,La3+的浓度为1.40×10-4 mol/L时,核酸能增强La3+ -CU络合物的荧光强度,而且体系荧光的增强程度与核酸的加入量在一定范围内呈线性关系.fsDNA,ctDNA和yRNA线性范围分别为7.00×10-4～10.00 mg/L,4.00×10-4～10.00 mg/L和7.00×10-4～10.00 mg/L；检出限分别为0.17,0.02和0.14 μg/L.与已报道的核酸的分析方法相比,本方法具有较宽的线性范围和较高的灵敏度.研究表明,核酸对体系荧光的增强源于DNA主链上PO3-4与CU之间的静电结合,以及通过氢键和疏水力进行的沟槽式结合,为探针分子提供了疏水性的微环境,降低了体系的非辐射能量损失,使体系的荧光强度增加.

Fluorescence Enhancement of Lanthenum-CurcuminCetyltrimethylammonium Bromide-Nucleic Acid System for Determination of Nucleic Acids

Curcumin(CU) is an extremely rare natural diketones antioxidant used as anti-inflammatory and anticarcinogenic agents.A new fluorimetric method for the determination of nucleic acid was developed based on the enhanced fluorescence system La3+-curcumin(CU)-cetyltrimethylammonium bromide(CTMAB)-nucleic acid.In this system,in hexamethylene-tetramine-HCl buffer(pH=5.80),1.00×10-3 mol/L CTMAB,2.00×10-5mol/L CU,1.40×10-4 mol/L La3+,nucleic acids can enhanced the fluorescence intensity of La3+-CU-CTMAB and the enhanced intensities are quantitatively in proportion to the concentrations of nucleic acids in the range of 7.00×10-4-10.00 mg/L for fsDNA,4.00×10-4-10.00 mg/L for ctDNA and 7.00×10-4-10.00 mg/L for yRNA,with corresponding detection limits(S/N=3) of 0.17,0.02,0.14 μg/L.A comparison between the proposed method and other analysis methods for nucleic acids was made.The results show that this method has a relatively wide linear range and high sensitivity.Study on reaction mechanism reveals that the phosphate group of nucleic acid can bind with CU through electrostatic attraction and meanwhile CU can interact with nucleic acid in the mode of groove binding.Such binding force changes the hydrophobic microenvironment of fluorescence probe,decrease the nonradioactive energy loses of the system and enhance its fluorescence intensity.