Surface modification of poly(L-lactic acid) film with bioactive materials by a novel direct alkaline treatment process

Poly(L-lactic acid) (PLLA) surface, which is difficult to be modified because there are no usable functional groups on it, was chemically modified by reacting directly with an alkaline solution of gelatin. The amount of immobilized gelatin reached 2 mu g/cm(2) depending on the reaction time and pH of gelatin solution, which was 10 times larger than that in the case of physical adsorption. The method developed here is biologically safe since no toxic chemical coupling reagent is used. The number of 3T3 fibroblasts attached on the gelatin-modified PLLA surface increased with the increasing amount of immobilized gelatin. The cell attachment was inhibited by preincubating the cells in the gelatin-containing medium. This method is easy and effective to impart good cell attachment property to the PLLA surface. The immobilized gelatin molecules can also be utilized as graft molecules having various functional groups through which bioactive molecules such as cell adherent peptide, growth factor, and differentiation-inducing moiety can be immobilized.