The present invention is useful in screening for biomarkers associated with any other disease or condition. Such diseases and conditions range from the neurological diseases, autoimmune diseases and cancers identified above as well as any other disease or condition that has a biomarker such as an antibody or other characterizing protein or biomolecule associated with the disease or progression of the disease. The large ligand libraries of the invention can be used directly in biological fluid, under the appropriate experimental conditions and according to the processes recited herein, to screen for such markers and without the need to use fewer support members (e.g. about 100,000 or less) or without the need to transfer such peptoids or ligands to a microarray before screening the biological fluid. In addition, the ligand libraries may also be used to screen for cell based receptors that specifically relate to a particular cell surface marker.