Surface modification of PDMS substrates for tumour cell adhesion: Influence of roughness parameters

Surface properties play a key role in how biomaterials interact with the environment. Surface topography has also been reported to be influential in some research, although its effect is still not well elucidated. In this study, nano-roughened polydimethylsiloxane (PDMS) substrates were developed through a chemically etched intermediate surface. Additionally, PDMS substrates containing 10–30 μm diameter micropillars were functionalized with multilayers of chitosan (CHI) and hyaluronic acid (HA) via layer-by-layer. Such substrates were submitted to cell adhesion assays with PC3 tumour cells. The characterization of these substrates was carried out using an atomic force microscopy (AFM), and some roughness parameters were estimated. Through a statistical description of the topography, we investigated the effects of these surface parameters on PC3 cell adhesion. AFM results indicated a significant modification in the PDMS surface topography and the cell adhesion assays suggest that smoother surfaces induce the PC3 cell adhesion, especially the ones with a high Hurst exponent value. In addition to the AFM analysis, the surface modification of the LbL-functionalized substrates was monitored by contact angle and UV-visible measurements. The improved wettability and the significant Alcian Blue absorbance of the functionalized substrates suggest that the HA/CHI film deposition was successfully accomplished. The LbL functionalization increased the cell capture potential of the PDMS substrates, in which lower diameter micropillars favour the cell adhesion mechanism. Although much work is still needed, the findings advance progress towards the fundamental understanding of the role of nanoscale fractal roughness in cell adhesion and can contribute to the development of new biomaterials with applications in biomedical systems, such as biosensors.