Chalcogenide Thin Film Substrate for Protein Biochip Application

Diagnostic of pathogen in the human biological liquids by biochip technology is an intensively developed methodic now. The main and the most important part of biochip is the adsorbing layer. Adsorption properties of chalcogenide films to protein (rat monoclonal antibodies) were tested. The films were prepared by conventional thermal deposition technique and by pulsed laser deposition technique. Two methods were used for forming in the films the two-dimensional map of adsorbing places for probe testing. One is using photoresist properties of chalcogenide films; another is using photo-induced oxidation of chalcogenide films. It was shown Good selectivity of the developed structures to protein markers was shown. 1. Introduction Diagnostic of pathogen in the human biological liquids by biochip technology is an intensively developed methodic now. The most important part of biochip is the adsorbing layer. There are two main problems in developing this layer. One is creation of pattern on the film-surface and the second is achievement of selectivity of adsorption of protein or DNA to the created pattern [1]. Chalcogenide glasses have ability to adsorb biological materials [2]. Besides, chalcogenide glasses, for example, of the As-S system have photostructural transformations under irradiation of light with energy above band gap [3]. These transformations are characterized by changes in the chemical short-range structure and some properties. It can be used for creation of precision island structure with photoresist technology. Also, Ge-Ga-S glassy films undergo photo-induced oxidation under exposure to photons with energy above the band gap [4]. It results in fundamental changes in the chemical structure. Both these effects can be used for forming two-dimensional map of places for adsorbing of probe at the films taking into account supposition that chalcogenide and oxide glasses have different ability to adsorb amine groups of proteins or DNA. Methods of patterning and adsorption properties of chalcogenide films to protein or DNA were investigated in this work for the biochip application. 2. Experimental The glasses of As39S61 and Ge26Ga9S65 compositions were synthesized in evacuated quartz ampoules from elementary arsenic and sulfur or elementary germanium, gallium, and sulfur. The prepared As39S61 glass was used to deposition of thin films onto standard glass slide by thermal deposition. The film thickness was about 500？nm. The synthesized Ge26Ga9S65 glass was used for preparation of the thin films by pulsed laser deposition (XeCl laser was used). Pulsed