Study on interactions of aminoglycoside antibiotics with calf thymus DNA and determination of calf thymus DNA via the resonance Rayleigh scattering technique.

A simple and sensitive resonance Rayleigh scattering (RRS) spectra method was developed for the determination of calf thymus DNA (ctDNA). The enhanced RRS signals were based on the interactions between ctDNA and aminoglycoside antibiotics (AGs) including kanamycin (KANA), tobramycin (TOB), gentamicin (GEN) and neomycin (NEO) in a weakly acidic medium (pH 3.3-5.7). Parameters influencing the method were investigated. Under optimum conditions, increments in the scattering intensity (∆I) were directly proportional to the concentration of ctDNA over certain ranges. The detection limit ranged from 12.2 to 16.9 ng/mL. Spectroscopic methods, including RRS spectra, absorption spectra and circular dichroism (CD) spectroscopy, coupled with thermo-denaturation experiments were used to study the interactions, indicating that the interaction between AGs with ctDNA was electrostatic binding mode.