In situ modification of cell-culture scaffolds by photocatalytic decomposition of organosilane monolayers

Abstract

We demonstrate a novel application of TiO2 photocatalysis for modifying the cell affinity of a scaffold surface in a cell-culture environment. An as-deposited octadecyltrichlorosilane self-assembled monolayer (OTS SAM) on TiO2 was found to be hydrophobic and stably adsorbed serum albumins that blocked subsequent adsorption of other proteins and cells. Upon irradiation of ultraviolet (UV) light, OTS molecules were decomposed and became permissive to the adhesion of PC12 cells via adsorption of an extracellular matrix protein, collagen. Optimal UV dose was 200 J cm(-2) for OTS SAM on TiO2. The amount of collagen adsorption decreased when excessive UV light was irradiated, most likely due to the surface being too hydrophilic to support its adsorption. This UV-induced modification required TiO2 to be present under the SAM and hence is a result of TiO2 photocatalysis. The UV irradiation for surface modification can be performed before cell plating or during cell culture. We also demonstrate that poly(ethylene glycol) SAM can also be patterned with this method, indicating that it is applicable to both hydrophobic and hydrophilic SAMs. This method provides a unique tool for fabricating cell microarrays and studying dynamical properties of living cells.

Surface Modification of Cell Scaffold in Aqueous Solution Using TiO₂Photocatalysis and Linker Protein L2 for Patterning Primary Neurons<i></i>

“…Next, focused UV light was irradiated to the coverslip through the microscope objective at a dose of 600 J cm −2 . At around this dose, the SAM on the TiO 2 is completely decomposed [27]. Finally, RPL2-GFP was applied to the surface, and GFP fluorescence was imaged to compare the affinity of RPL2 to the intact and UV-irradiated regions.…”

“…Yet the un-necessity of resists can be an advantage in some applications, since residual photoresist can be cell toxic [35]. Most importantly, the method described here is potentially capable of processing surfaces in cell culture environment [27]. Use of the RPL2-tagged Ln is critically important for such an experiment since it has very little non-specific adsorption, in contrast to polylysine (Fig.…”

“…The method to prepare the TiO 2 /glass coverslip modified with the organosilane SAMs was described elsewhere [27]. To remove the additional organosilane molecules, the coverslips were sonicated in toluene and ethanol, in that order.…”

“…To overcome the first issue, we very recently developed a novel surface modification method that takes advantage of titanium dioxide (TiO 2 ) photocatalysis to decompose non-permissive compounds upon irradiation of ultraviolet (UV) light [27]. This method does not require short pulse lasers and is free from generation of the cavitation bubbles.…”

Autonomous patterning of cells on microstructured fine particles

“…The fabricated scaffolds were sterilized by ultraviolet radiation for one day before incubation. The sterilization process (UV irradiation) also induces the OTS-molecules to be decomposed, so that the cell adhesiveness of OTS-covered glass improves to the degree of pristine glass [11]. Fig.…”