Direct adsorption of chemically modified biomolecules onto gold: a rapid method for biological functionalization of MEMS

The present work reports a simple, rapid and versatile strategy for glycoprotein immobilization, based on the targeted functionalization of carbohydrate residues with disulphide "anchors" derivatives able to spontaneously chemisorb onto gold, with no need of surface pre-functionalization. Different glycoproteins as enzymes and antibodies were chemically modified using this "one step" bio-immobilization protocol and directly adsorbed onto gold coated interfaces. Surface plasmon resonance (SPR) and Electrochemistry techniques revealed that direct adsorption of a modified glyco-enzyme (horseradish peroxidase) onto gold led to the formation of a densely packed SAM, where each single biomolecule is several thousand times more active than a non modified one. In the case of antibodies, the specific location of the carbohydrate moieties in the constant region resulted in the formation of active and site-oriented SAMs. This bio- immobilization method was applied to the bio- functionalization of a degenerate mode MEMS sensor (MEMSens). Preliminary results obtained for the detection of protein S-100ββ (brain injury marker), indicate a promising low detection limit.