Methods of detection are provided, comprising (i) obtaining a. sample, wherein the sample comprises target selected from biological cells and viruses; (ii) incubating the sample with polymer-coated magnetic beads to produce bead-target complexes; (iii) analyzing the bead-target complexes by Raman spectroscopy to produce a spectrograph; and (iv) detecting the presence of the bead-target complexes by analyzing the spectrograph.