Poly(dimethylsiloxane) contamination in microcontact printing and its influence on patterning oligonucleotides

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Microcontact printing (muCP) utilizes poly(dimethylsiloxane) (PDMS) stamps for precise molecular transfer.
• Unintended transfer of siloxane fragments from PDMS stamps to substrates, known as contamination, impacts printing fidelity.
• The precise role of siloxane contamination in muCP remains incompletely understood.

Purpose of the Study:

• To investigate the kinetics of siloxane contamination during muCP.
• To evaluate the influence of PDMS curing conditions and contact time on substrate contamination.
• To assess the effect of siloxane contamination on the quality of muCP, particularly with DNA inks.

Main Methods:

• Surface characterization of stamps and substrates post-printing to analyze contamination.
• Controlled variation of PDMS curing conditions and contact times.
• Development and testing of a stamp cleaning procedure.
• Comparison of muCP performance using cleaned versus uncleaned PDMS stamps with fluorescent DNA.

Main Results:

• Siloxane contamination levels are influenced by PDMS curing conditions and contact time.
• A proposed multi-hour cleaning process effectively removes siloxane contamination from PDMS stamps.
• Hydrophobicity recovery of oxygen plasma-treated PDMS is significantly delayed by the cleaning procedure.
• Uncleaned PDMS stamps, exhibiting siloxane contamination, resulted in higher DNA transfer during muCP.

Conclusions:

• Siloxane contamination, previously considered detrimental, positively impacts muCP by enhancing oligonucleotide adsorption.
• The presence of low molecular weight siloxane fragments on PDMS stamps can improve the efficiency of DNA printing.
• Understanding and potentially controlling siloxane transfer could optimize muCP processes for specific applications.