Disclosed are genetically-modified phages, comprising a first nucleic acid sequence encoding at least a first peptide able to bind to a magnetic nanoparticle, and a second nucleic acid sequence encoding at least a second peptide able to bind with high specificity to a predetermined biomarker, and a method for using the genetically-modified phage displaying the first peptide and second peptide in a method for analyzing a fluid sample for the predetermined biomarker.
