Abstract: Systems and methods for enhancing quantitative transfer of analytes to an adsorptive substrate are provided. A preferred embodiment provides an improved transfer system and method that reduces “blow through” of low molecular weight analytes and increases the adsorption of low molecular weight, for example proteins of about 30 kDa or less compared to conventional transfer techniques. It has been discovered that using a secondary porous backing membrane in conjunction with an adsorptive membrane such as nitrocellulose or polvinylidene fluoride increases the efficiency of analyte interaction with the adsorption membrane compared to transfers techniques using the adsorption membrane without the secondary backing membrane. This improvement of quantitative analyte transfer efficiency facilitates a wider range of detection processes, such as direct analysis by MALDI mass spectrometry than in earlier applications of the process without the secondary backing membrane.

Abstract: In a cardiac monitoring method, at east an inactive natriuretic peptide (22) and an active natriuretic peptide (20) are assayed in a biological sample taken from a patient. Both the inactive and active natriuretic peptides are produced in the patient responsive to cardiac stress. A therapeutic agent (26), such as a synthetic or mimetic natriuretic peptide, is administered to the patient. The administered therapeutic agent substantially interferes with the active natriuretic peptide assay but does not substantially interfere with the inactive natriuretic peptide assay. Kinetics of the administered therapeutic agent are determined based on at least the active natriuretic peptide assay. Cardiac diagnostic information is determined based on at least the inactive natriuretic peptide assay.

Abstract: The present invention relates to a device method and kit for the convenient and rapid isolation and purification of nucleic acids, proteins, peptides, carbohydrates and oligosaccharides from heterogeneous biological samples. The device comprises a membrane assembly comprised of layers of microporous, polymeric membranes functionalized with ion-exchange groups. The device is reusable for like samples, relatively inexpensive compared to currently available separation techniques and is disposable, thereby avoiding cross-contamination of biological samples.

Abstract: A membrane suitable for immobilizing peptides and proteins is disclosed. The membrane is a flexible, polymeric, porous membrane which contains functional groups capable of covalently linking the peptides and proteins. The functional groups can be provided by reacting the membrane itself or a coating thereon with nucleophiles which provide --NH.sub.2, --SH, --OH or --COOH functionality to the membrane surface. Additionally, surfaces containing --NH.sub.2 groups can be further reacted with diisothiocyantes to provide an isothiocyanate functionality having enhanced covalent binding characteristics.

Abstract: A hydrophobic material having a crosslinked, cationic charge-modifying coating such that the majority of the ion exchange capacity of the material is provided by fixed formal positive charge groups is disclosed. The material is produced by contacting a hydrophobic substrate with a mildly alkaline, aqueous organic solvent solution into which has been dissolved a cationic charge-modifying agent. The charge-modifying agent comprises a water soluble, organic polymer having a molecular weight of greater than about 1000, wherein the polymer chain contains both fixed formal positive charge groups and halohydrin groups.Materials of the type described herein can be used in a variety of applications including macromolecular blotting and filtration.