Application of L-cysteine-capped ZnS nanoparticles in the determination of nucleic acids using the resonance light scattering method

Nanometer-sized L-cysteine-capped ZnS particles were synthesized by a colloidal aqueous method. The functionalized nanoparticles are water-soluble and suitable for biological applications. In Tris-HCl buffer solution, nucleic acids combine with cysteine-capped nano-ZnS particles by intermolecular forces to form larger nanoparticles. There are two resonance light scattering peaks at 304.5 nm and 373.8 nm, respectively. The enhanced RLS is related to the concentration of nucleic acids in the range of 0.04 to 1.2 mug mL(-1) for calf thymus DNA and 0.2 to 1.0 mug mL(-1) for fish sperm DNA. The detection limits (3delta) are 19 ng mL(-1) for calf thymus DNA and 23 ng mL(-1) for fish sperm DNA, respectively. Four synthetic samples were analyzed satisfactorily.