The wettability and topography of self-assembled protein monolayer linked by alkanethiols

Protein interactions have great significance in biomedical and bioengineering research. It is a challenge to form an ideal protein surface. Self assembled monolayers (SAMs) is a rather new chemical method which is easily handled to fabricate a well defined protein surface. In this work, we performed alkanethiol monolayers with carboxyl end groups, and mixed alkanethiols monolayers with carboxyl and methyl end groups. Self assembled alkanethiols films with carboxyl end groups were activated by 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride (EDC), and N-Hydroxysulfosuccinimide (NHS), then immersed into human IgG solution, formed protein layers. Protein layers were investigated by atomic force microscopy (AFM) to acquire high resolution 2-D and 3-D topography images, and contact angle goniometry to characterize the wettability of the surfaces. AFM images of bare gold and protein layers showed significant differences in topography and heights. It suggested that protein was uniformly linked with the alkanethiols films. This was also supported by comparing the contact angle of alkanethiols films and protein surfaces. This work could be extended to microarray.