Coprecipitation of DNA and calcium phosphate using an infusion fluid mixture

A surface-mediated gene transfer system using DNA-calcium phosphate (CaP) composite layers (D-CaP layers) would be useful in tissue engineeing. In previous studies, D-CaP layers were fabricated in supersaturated CaP solutions prepared using chemical reagents. In this study, a so-called RKM solution prepared using clinically approved infusion fluids was employed as a supersaturated CaP solution. A D-CaP layer consisting of submicron spherical particles was successfully fabricated on a polystyrene substrate by immersing the substrate in the RKM solution for 24 h. When the immersion period was prolonged from 24 to 72 h, amount of CaP and DNA on the substrate increased. However, the gene transfer capability of the D-CaP layer for the CHO-Kl cells was kept unchanged irrespective of the immersion period. In the RKM solution process, immersion period of 24 h was found to be long enough for gene transfer application of the D-CaP layer. More importantly, the D-CaP layer fabricated by the RKM solution process exhibited a significantly higher gene transfer capability than our previous D-CaP layer fabricated in the conventional CaP solution with the same DNA concentration. The RKM solution process for the fabrication of D-CaP layers was found to be advantageous to the previous process in terms of not only safety but the layer's gene transfer capability.