An affinity substrate for the selective binding of a protein of blood plasma includes a solid substrate material on which are immobilized deoxyribonucleic aptamers specifically binding with the plasma protein.

The present invention provides a pipette tip, which can be used in in-vitro diagnostics, in particular in the diagnostic testing of body fluids, such as in coagulation testing. The Pipette tip contains two constituents in a spatially separated manner. The present invention furthermore provides a method of performing such diagnostics, e.g. coagulation analysis, and to the use of the pipette tip in such diagnostic testing.

The invention relates to commercially viable methods for producing biologically active vitamin K dependent proteins, particularly Factor IX. Factor IX is produced at a level of at least about 15 mg/L and is at least 25% biologically active. The method relies upon co-expression of one or more of paired basic amino acid converting enzyme (PACE), vitamin K dependent epoxide reductase (VKOR) and vitamin K dependent -glutamyl carboxylase (VKGC) at a preferred ratio so that the vitamin K dependent protein is efficiently produced and processed by a recombinant cell.