Surface functionalization of germanium ATR devices for use in FTIR-biosensors.

Biosensors based on intrinsic detection methods have attracted growing interest. The use of Fourier transform infra-red (FTIR) spectroscopy with the attenuated internal total reflection (ATR) mode, in the biodetection context, requires appropriate surface functionalization of the ATR optical element. Here, we report the direct grafting of a thin organic layer (about 20 A depth) on the surface of a germanium crystal.

Ligand-receptor interactions in complex media: a new type of biosensors for the detection of coagulation factor VIII.

Detection of receptor-ligand interaction in complex media remains a challenging issue. We report experimental results demonstrating the specific detection of the coagulation factor VIII in the presence of a large excess of other proteins using the new BIA-ATR technology based on attenuated total reflection Fourier transform infrared spectroscopy. The principle of the detection is related to the ability of factor VIII molecules to bind to lipid membranes containing at least 8% phosphatidylserine.

Biochemical interaction analysis on ATR devices: a wet chemistry approach for surface functionalization.

A new generic device suitable for the investigation of ligand-receptor interactions is presented. In particular, the research focused on optical waveguides constituted by an attenuated total internal reflection (ATR) element, transparent in the infrared and whose surfaces were activated in view of covalently binding a receptor. Silicon and germanium ATR elements were considered.

A practical molecular clip for immobilization of receptors and biomolecules on devices' surface: synthesis, grafting protocol and analytical assay.

Deposition of O-succinimidyl 4-(p-azido-phenyl)butanoate (4) onto inorganic device (FTIR-ATR crystal) or polymer material (filtration membrane) followed by irradiation at 254nm led to surface functionalisation with NHS esters. Further reaction with biomolecules allowed their covalent grafting. The reactivity of the photoactivated surfaces was assayed by two methods: (i) the coupling with 3,5-bis(trifluoromethyl)benzylamine (7) and subsequent XPS analysis; (ii) the coupling with 4,5-bis-tritiated lysine (10) and subsequent LSC measurement of the radioactivity.