Fluorescence intensity A B Fluorescence intensity Wavelength [nm] Supplemental Data Figure 1. (A) TEM images of affinity magnetic beads (left) and FF beads (right). (B) Fluorescence spectra of FF beads. Red, Blue, and Green lines represent 100, 30, and 10 mg of FF beads, respectively.

Fluorescence counts [cps] Concentration [pg/mL] Supplemental Data Figure 2. Detection of BNP in plasma by sandwich immunoassay using anti-BNP antibody-coated FF beads. The incubation time with magnet is 1.5 minutes. All data are expressed as means ± SD of five measurements.

Fluorescence counts [cps] Concentration [ng/mL] Supplemental Data Figure 3. Detection of PSA in serum by sandwich immunoassay using anti-PSA antibody-coated FF beads. The incubation time with magnet is 1 minute. All data are expressed as means ± SD of three measurements.

A B Supplemental Data Figure 4. Immunohistochemical staining of tissues from esophageal cancer cells using (A) anti-EpCAM antibody-coated FF beads and (B) anti-CK19 antibody-coated FF beads. Left, HE staining; Middle, paraffin-embedded staining; Right, immunohistochemical staining with magnetic collection of FF beads.