Plasma Treatment of PDMS for Microcontact Printing (μCP) of Lectins Decreases Silicone Transfer and Increases the Adhesion of Bladder Cancer Cells

The present study investigates silicone transfer occurring during microcontact printing (mu CP) of lectins with polydimethyl-siloxane (PDMS) stamps and its impact on the adhesion of cells. Static adhesion assays and single-cell force spectroscopy (SCFS) are used to compare adhesion of nonmalignant (HCV29) and cancer (HT1376) bladder cells, respectively, to high-affinity lectin layers (PHA-L and WGA, respectively) prepared by physical adsorption and mu CP. The chemical composition of the mu CP lectin patterns was monitored by time-of-flight secondary ion mass spectrometry (ToF-SIMS). We show that the amount of transferred silicone in the mu CP process depends on the preprocessing of the PDMS stamps. It is revealed that silicone contamination within the patterned lectin layers inhibits the adhesion of bladder cells, and the work of adhesion is lower for mu CP lectins than for drop-cast lectins. The binding capacity of microcontact printed lectins was larger when the PDMS stamps were treated with UV ozone plasma as compared to sonication in ethanol and deionized water. ToF-SIMS data show that ozone-based treatment of PDMS stamps used for mu CP of lectin reduces the silicone contamination in the imprinting protocol regardless of stamp geometry (flat vs microstructured). The role of other possible contributors, such as the lectin conformation and organization of lectin layers, is also discussed.

Automated summary

This study investigates the transfer of silicone and its impact on cell adhesion during microcontact printing. The results show that silicone contamination inhibits cell adhesion and microcontact printed lectins have lower adhesion compared to drop-cast lectins. Treatment of PDMS stamps with ozone reduces silicone contamination during the imprinting protocol.