Layer-by-Layer assembled growth factor reservoirs for steering the response of 3T3-cells.

Layer-by-Layer (LbL) assemblies of heparin (Hep) and chitosan (Chi) were prepared for use as reservoirs for acidic and basic fibroblast growth factors (aFGFs and bFGFs, respectively). The effects of the architecture and composition of the reservoirs on the viability and proliferation of NIH-3T3 fibroblast cells were studied under starvation conditions. The reservoir stability was monitored by ellipsometry. The aFGF and bFGF loadings were determined using a dissipation-enhanced quartz crystal microbalance (QCM-D). Stability and release assays were performed in a phosphate buffer at physiological conditions. The results demonstrated that the amount of aFGF and bFGF loaded into and released from LbL reservoirs composed of 3 and 6 layer pairs could be controlled. Cell culture assays in low serum culture medium (LSCM) demonstrated that incorporating very small amounts of aFGF and bFGF into the (Hep/Chi)n multilayers significantly improved the proliferation of the NIH-3T3 fibroblasts. The cells did not proliferate on (Hep/Chi)n assemblies prepared in the absence of FGF under identical conditions. The LbL reservoirs were highly effective for the long-term storage (up to 9 months) of aFGF and bFGF. This work demonstrates the potential of LbL reservoirs for use as biomaterial coatings.