A dual-wavelength resonance light scattering ratiometry of biopolymer by its electrostatic interaction with surfactant

A dual-wavelength resonance lighting scattering (DW-RLS) ratiometry is developed to detect anion biopolymer based on their bindings with cation surfactant. Using the interaction of Hyamine 1622 (HM) with fish sperm DNA (fsDNA) as an example, a dual-wavelength resonance light scattering (DW-RLS) ratiometric method of DNA was constructed. In Britton–Robinson buffer controlled medium, fish sperm DNA (fsDNA) could interact with Hyamine 1622 (HM), displaying significantly enhanced RLS signals. By measuring the RLS signals characterized at 300.0 nm (I300.0) and the RLS intensity ratio (I276.0/I294.0), respectively, fsDNA over a wide dynamic range of content could be detected. Typically, when HM concentration is kept at 6.0 × 10−5 mol l−1, using I300.0 could detect fsDNA over the range of 50–2000 ng ml−1 with the limit of 3.0 ng ml−1, while using I276.0/I294.0 could detect fsDNA over the range of 0.5–2500 ng ml−1 with the limit of 0.05 ng ml−1. Thus the latter so-called DW-RLS ratiometry is obviously superior to the former one. Based on the measurements of I300.0 and I276.0/I294.0 data, a Scatchard plot concerning the interaction between HM and fsDNA could be constructed and thus the binding number (n) and binding constant (K) could be available with the values of 13.5 and 1.35 × 105 mol−1 l, and 11.9 and 1.65 × 105 mol−1 l, respectively.