Abstract: The invention concerns a barrier (2) temporarily separating a reaction container (1) into at least a first compartment (3) wherein a reaction medium comprising an analyte and optionally a reagent is introduced and a second compartment (4) for receiving at least one of the elements among the reagent, the analyte and the reaction product, said barrier (2) being made of a material adapted to shift, by the action of a specific chemical substance, from a first state wherein said material is substantially impermeable to the reaction medium to a second state wherein said material is capable of allowing through at least one of said elements among the reagent, the analyte and the reaction product. The invention also concerns a container comprising such a barrier and a method for carrying out an assay in said container.

Abstract: The invention concerns a method for magnetising chemical or biological markers using magnetic particles, said method comprising steps which consist in: activating the magnetic particles so as to modify their surface state; contacting the activated magnetic particles with the markers so as to produce non-specific bonds between them. The invention also concerns the use of biological markers magnetised by said method as reagents or analytes in a biological assay.

Abstract: The invention concerns a biological assay device using a reaction between an analyte present in a fluid and a reagent capable of forming a complex with said analyte, wherein the analyte is in the form of cellular elements, said device comprising at least a reaction container (1) provided with a reaction zone (2) wherein are introduced the fluid and the reagent, and with an immobilizing zone (3) whereon is fixed a substance (4) capable of specifically binding with the possibly formed complexes, the reaction zone (2) and the immobilizing zone (3) being separated from each other by a material layer (8), said material being capable of shifting from one first state wherein the layer (8) is substantially impermeable to a second state wherein the layer (8) is capable of allowing through the cellular elements, whether complexed or not.