Regeneration of a thiolated and antibody functionalized GaAs (001) surface using wet chemical processes

Wet chemical processes were investigated to remove alkanethiol self-assembled monolayers (SAMs) and regenerate GaAs (001) samples studied in the context of the development of reusable devices for biosensing applications. The authors focused on 16-mercaptohexadecanoic acid (MHDA) SAMs that are commonly used to produce an interface between antibodies or others proteins and metallic or semiconductor substrates. As determined by Fourier transform infrared absorption spectroscopy, among the investigated solutions of HCl, H2O2, and NH4OH, the highest efficiency in removing alkanethiol SAM from GaAs was shown by NH4OH:H2O2 (3:1 volume ratio) diluted in H2O. The authors observed that this result was related to chemical etching of GaAs that even in a weak solution of NH4OH:H2O2:H2O (3:1:100) proceeded at a rate of 130 nm/min. The surface revealed by a 2-min etching under these conditions allowed depositing successfully a new MHDA SAM with comparable quality and density to the initial coating. This work provides an important view on the perspective of the development of a family of cost-effective GaAs-based biosensors designed for repetitive detection of a variety of biomolecules immobilized with dedicated antibody architectures.