Molecule responding to formula X-E-SiCl.sub.3 wherein: X represents an isocyanate function --N.dbd.C.dbd.O and B represents an alkyl chain, its use for preparing a device comprising a mineral support (MS) and bound thereto at Self Assembled Monolayer (SAM) of molecules, the Self Assembled Monolayer grafted substrate thus obtained and its use in assays for detection of a target molecule and/or screening of interaction with other molecules.