Resonance Light Scattering Imaging Detection of Single Suprahelical Species of DNA Induced by Porphine‐5,10,15,20‐tetrakis(p‐phenyltrimethylaminium)

Abstract

AbstractA resonance light scattering (RLS) imaging method was proposed based on imaging and measuring the RLS features of single suprahelical species of DNA, and its application to DNA assay was also investigated. In acidic medium, porphine‐5,10,15,20‐tetrakis(p‐phenyltrimethylaminium) (PTPTMA), could stack along the molecular surface of DNA with the mode of long‐range assembly to induce the formation of suprahelical species of DNA, resulting in strong RLS signals in the range of 450–510 nm. Under the excitation of 488 nm light beam of argon ion laser source, single suprahelical species could be observed with the aid of a common microscope due to the strong scattered light emitted by the suprahelical species. By capturing the RLS images of the single suprahelical species with a cooled charge coupled device (CCD) camera, and analyzing the RLS data, herein an RLS imaging method of DNA was proposed based on the linear relationship between the counts of suprahelical species in the detection focus plane and the concentration of DNA in nanograms. When 1.8??µmol/L PTPTMA was employed, both calf thymus DNA (ct DNA) and fish sperm DNA (fs DNA) in the range of 25–1100 ng/mL could be detected with the limits of detection lower than 25 ng/mL (3σ). Four synthetic samples were detected satisfactorily with relative standard deviations less than 5.1%.