Simple surface treatment of cell-culture scaffolds with ultrafine bubble water.

We propose a novel method to treat polymeric scaffold surfaces for cell culture with water containing nanobubbles, called ultrafine bubbles (UFBs), with typical diameters less than 1 μm. A thin film of polystyrene (PS) prepared on a solid substrate was exposed to UFB water for 2 days at room temperature. The PS surface was characterized by X-ray photoelectron spectroscopy (XPS), static contact angle measurements in water, and atomic force microscopy (AFM). The surface chemical composition and wettability of PS films remained unchanged after treatment, so that aggregation states of PS at film surfaces remained unaltered by UFB water. On the other hand, after treatment, many UFBs were adsorbed on hydrophobic PS surfaces. To study the effect of UFBs on scaffold properties, the adsorption behavior of fibronectin, which is a typical extracellular matrix protein involved in cell adhesion and proliferation, was examined. While the effect on the adsorption was unclear, the structural denaturation of fibronectin was enhanced after UFB treatment, so that the proliferation of fibroblast cells on PS surfaces was promoted.