Sprayed Cells and Polyelectrolyte Films for Biomaterial Functionalization: The Influence of Physical PLL–PGA Film Treatments on Dental Pulp Cell Behavior

Figure S1. (Spray deposition of polyelectrolyte multilayers; (A): Quantity of solution deposited by spraying; (B): Volume of sprayed solution deposited on samples for 0.57ml (four spraying) and 1.27 ml (eight spraying) total deposited volume; (C): Total spray image (St: diameter = 7 cm and the disk surface (Ss: diameter = 1.4 cm). Contact angle measurements have been performed to characterize the surface of PEM's. A sessile drop of the reference liquid (water in our case) was applied with a syringe onto a specimen, which was placed on a plate capable of moving in three dimensions. Specimens were dried for 5 min in air at room temperature before the drop deposition. Water drop profiles were recorded with a CCD camera connected to a video-acquisition card. Contact angles were measured and recorded with ImageJ software (NIH, Bethesda, MD, USA, http://rsb.info.nih.gov/ij/). The contact angle of a water drop was measured after each layer deposition. Contact angles were determined by averaging data obtained at five different spots (one measurement per spot) after each polyelectrolyte adsorption step. Contact angle measurements during (PLL-PGA)₅-PLL construction showed an increase of hydrophobicity after PLL adsorption, and of hydrophilicity after PGA deposition (Figure S2). There is no statistically significant difference (p = 0.156) between the contact angle of glass surface and that of the (PLLPGA)₅PLL films (PLL 6 on Figure S₂). The mean contact angle of a water drop was 64°±3° on the PEM surface, while it was 57° ± 3° on the bare glass surface.

Figure S2. Contact angle changes during (PLL-PGA)₅-PLL film build up; Five measurements have been done for each PEM deposition on five different glass disks. PLL increased the hydrophobicity, in contrast, PGA increased the hydrophilicity of the film surface.) Contact angle measurements showed alternating changes according to the nature of the last-adsorbed polyelectrolyte. Multilayers having PLL as the outermost layer were more hydrophobic than those of terminated by PGA, most probably due to the lower polarity of the PLL head-group, similarly as in the case of polyallilamine/polystyrenesulfonate (PAH/PSS) multilayers. The difference between the contacts angles became more expressed as the number of layers grew, i.e. as the structure of the PLL/PGA film became more perfect.