Abstract: Provided herein are methods, compositions, and kits for preparing biological samples for multiplex spatial gene expression and proteomic analysis, such as determining a location of a nucleic acid analyte and a protein analyte in a biological sample.

Abstract: An apparatus includes an electrochemical cell with an electrolyte solution containing particles and metal ions; an electrode system disposed in the electrolyte solution, wherein the electrode system includes a counter electrode, a reference electrode, and a working electrode, and wherein the counter electrode and the working electrode are arranged to allow electric current to flow therebetween; and an open-bore magnet arrangement having at least one permanent magnet connected to the electrochemical cell and arranged to produce a magnetic field in the electrolyte solution to interact with the electric current to produce an electrodeposition of the particles with metal derived from the metal ions onto the working electrode.