Method for performing molecular reactions by using immiscible intermediate fluids

The present invention relates to a method for performing molecular reactions in a device comprising the steps of (a) introducing one or more reagent solution(s) and an immiscible intermediate fluid into the device, wherein the device comprises a substrate, on which chemically or biochemically recognizable entities are immobilized; (b) performing molecular reactions between the immobilized chemically or biochemically recognizable entities and the reagent solution(s); or on the immobilized chemically or biochemically recognizable entities in the presence of the reagent solution(s); (c) displacing the reagent solution(s) present on the substrate by the immiscible intermediate fluid; (d) separating the immiscible intermediate fluid and the reagent solution(s); and reusing the reagent solution(s) and/or immiscible intermediate fluid for one or more repetitions of steps (a) to (e). The invention further relates to a device for performing a molecular reaction, comprising a reaction zone, reservoirs and liquid connections and a collection and regeneration zone wherein the immiscible intermediate fluid and the reagent solution(s) are separable by gravitational separation; or a redirection and distribution module, wherein the immiscible intermediate fluid and reagent solution(s) are separated. The invention also relates to the use of an immiscible intermediate fluid for displacing a reagent solution present in a reaction zone in a microfluidic device, as well as the use of a corresponding device for performing a sequencing reaction or a nucleic acid synthesis reaction