Abstract: A piezoelectric biosensor substrate useful for immobilizing biomolecules in an oriented manner on the surface of a piezoelectric sensor has a ladder polymer of polyacrylonitrile. To make the substrate, a solution of an organic polymer, preferably polyacrylonitrile, is applied to the surface of a piezoelectric sensor. The organic polymer is modifying by heating the polymer in a controlled fashion in air such that a ladder polymer is produced which, in turn, forms the attachment point for the biomolecules comprising the piezoelectric biosensor.

Abstract: Hybridomas are provided which secrete an IgG1 or IgG2 monoclonal antibody which binds to an epitope on an antigen, which occurs in the plasma membrane of MCF-7 cells and has a molecular weight of 22 kD. The epitope of the antibodies is exposed on the extracellular side of the plasma membrane of the MCF-7 cells. The monoclonal antibodies, which react generally with human mammary carcinoma cells, but with few non-mammary cancer cells, are useful diagnostically and therapeutically.

Abstract: An hybridoma cell line and the monoclonal antibody produced thereby are provided. The monoclonal antibody is specific for antigen found almost exclusively in the cytoplasm of human mammary tumor cells. The antibody is useful in diagnosing mammary tumors.