Patterning of Polystyrene by Scanning Electrochemical Microscopy. Biological Applications to Cell Adhesion

Abstract

Polystyrene surfaces may be patterned by Ag(II), NO(3)(•), and OH(•) electrogenerated at the tip of a scanning electrochemical microscope. These electrogenerated reagents lead to local surface oxidation of the polymer. The most efficient surface treatment is obtained with Ag(II). The patterns are evidenced by XPS and IR and also by the surface wettability contrast between the hydrophobic virgin surface and the hydrophilic pattern. Such Ag(II) treatment of a polystyrene Petri dish generates discriminative surfaces able to promote or disfavor the adhesion of proteins and also the adhesion and growth of adherent cells. The process is also successfully applied to a cyclo-olefin copolymer and should be suitable to pattern any hydrogenated polymer.

Control of mesenchymal stem cell phenotype and differentiation depending on cell adhesion mechanism

“…The plates were then washed three times with PBS. Atomic force microscopy (AFM) was used to characterise the topography of PS surfaces coated with MBP-FGF2, which showed the PS surface to be densely covered by 10 µg/mL of MBP-FGF2 (Ktari et al, 2010) (Fig. 1C).…”

Local Oxidation of Polystyrene by Scanning Electrochemical Microscopy

“…PS could also be oxidized by electrogenerating at the tip either the NO 3 • or the OH • radical. 18, 23 We have shown that the former species requires more constraining experimental conditions, while the latter oxidizes less efficiently the surface. XPS and FT-IRRAS showed that the oxidative treatment is confined to the upper few nanometers of the polymer and represents 10À25% of surface composition.…”

“…As proposed earlier, the approach curves with electrogenerated Ag 2+ are obtained by holding the SECM tip at potentials corresponding to mass-transfer limited currents (E = 1.72 V/saturated calomel electrode (SCE)). 18 For Ag + solutions between 10 À3 and 7 Â 10 À2 M, the steady-state current is linearly dependent on the Ag + concentration ( Figure 1). The diffusion coefficient of Ag + , D, is deduced from the slope of the straight line in Figure 1, using the relationship for ultramicroelectrode (UME) mass-transfer limited currents (i T,inf = 4nFDCa, with C being the concentration of the species submitted to oxidation and a being the UME radius).…”

“…This agrees with the spectroscopic analyses (XPS and Fourier transform infrared reflection adsorption spectroscopy (FT-IRRAS)) of the etched surfaces, which show that the etching is limited to a few tens of nanometers, the photoelectron mean free path. 18 When the Ag + content is increased from 10 À3 to 10 À2 M (respectively brown 4 and pink ) in Figure 2A), the normalized tip current decreases, and the apparent heterogeneous rate constant, k app , estimated from the approach curves decreases accordingly (green 2 in Figure 3A). Such concentration effects on heterogeneous kinetics are usually observed when the number of accessible reactive sites is lower than the mediator concentration.…”

New Strategy for Electrochemical Micropatterning of Nafion Film in Sulfuric Acid Solution

“…Previous literatures reported that hydroxyl radical generated from Fenton reaction could cause the decomposition of polymers. [41][42][43] However, we have never managed to find a suitable scavenger for Fenton reaction, because hydrogen peroxide is a strong oxidant used as the precursor of Fenton regent.…”