Micropatterning of covalently attached biotin on poly(lactic acid) film surfaces

A two-step approach was used to micropattern covalently attached biotin on the surface of poly(lactic acid) (PLA) film. Poly(acrylic acid) (PAA) was micropatterned on PLA using photolithography in step 1, followed by carbodiimide wet chemistry to covalently attach biotin to acid groups in step 2. The PAA micropatterning reaction progression was monitored using attenuated total reflectance-Fourier transform infrared (ATR-FT-IR) spectroscopy, water contact angle goniometry, and atomic force microscopy (AFM). The PAA-biotin conjugation reaction characterization using XPS confirmed the carbodiimide mediated amidation reaction. The resultant PLA film was then immersed into a solution of fluorescence-conjugated streptavidin and examined under fluorescence microscopy to reveal various micropatterns.