A total of 0.0001 g of TiO2 spheres and 40 μL of antibody (1 wt %) were added to 450 μL of PBS at 4 °C for half an hour for premixing. After premixed, 50 μL of EDC (2 wt %) and 50 μL of 5 M N-hydroxysuccinimide (NHS) was added to the solution at 4 °C for 4 h to induce an EDC coupling reaction, and the final products were washed four times in PBS to remove residual EDC and antibodies and transferred to 500 μL of 5 wt % milk solution.