Photochemical approach for multiplexed biofunctionalisation of GaAs

The optoelectronic properties of gallium arsenide (GaAs) hold great promise in biosensing applications, currently being held back by the lack of methodologies reporting the functionalisation of this material with multiple biomolecules. Here, we exploit the use of a photoreactive crosslinker - a diazirine derivative - for spatially selective covalent immobilisation of multiple bioreceptors on the GaAs surface. As a proof of principle we show the immobilisation of two proteins: neutravidin and endosulfine alpha protein. X-ray photoelectron spectroscopy results showed the presence of the biomolecules on the GaAs regions selectively exposed to UV light. The approach presented here is applicable to the covalent attachment of other biomolecules, paving the way for using GaAs as a platform for multiplexed biosensing.