Covalent grafting of polythymidylic acid onto amine-containing polystyrenelatex particles

The covalent grafting of a 35-base poly(thymidylic) acid (dT(35)) onto amin ated polystyrene latex has been studied. The oligonucleotide was activated by 1,4-phenylene diisothiocyanate (PDC) prior to grafting reaction. The inf luence of various experimental conditions related either to the medium (pH, ionic strength) or to the latex (nature and surface charge density, presen ce of adsorbed nonionic surfactant) was studied. Discrimination between cov alent grafting and adsorption was achieved by desorbing the non-covalently grafted dT35 induced by consecutive washings with a suitable buffer solutio n. The amount of covalently grafted oligonucleotide directly correlated to the concentration and accessible functional groups at the particle surface.