Immunomagnetic diffractometry for detection of diagnostic serum markers

J Am Chem Soc. 2007 Dec 26;129(51):15824-9. doi: 10.1021/ja073094m. Epub 2007 Nov 30.


We describe an integrated approach for detection of diagnostic markers using in situ assembled optical diffraction gratings in combination with immunomagnetic capture. Folate receptor (FR), a serum protein indicative of various cancers, was chosen as a model system to demonstrate the potential of the method. Magnetic beads coupled to FR antibody were used to capture FR from serum. The FR-bound magnetic beads self-assembled onto microcontact-printed folate-coupled BSA (F-BSA) patterns to form diffraction gratings which served to detect FR by measuring the diffraction intensities caused by laser illumination. The FR-containing beads, upon binding to the F-BSA surface, served as intrinsic signal enhancement agents, circumventing the need for additional enzymatic signal amplification or fluorescent labeling steps. With this approach, a detection sensitivity of 700 fM (20 pg/mL) was achieved. The potential use of this approach in clinical diagnostics was demonstrated by measuring FR concentration in blood samples obtained from cancer patients.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biomarkers / blood*
  • Carrier Proteins / blood*
  • Carrier Proteins / chemistry
  • Enzyme-Linked Immunosorbent Assay
  • Folate Receptors, GPI-Anchored
  • Humans
  • Immunomagnetic Separation*
  • Polymerase Chain Reaction
  • Receptors, Cell Surface / blood*
  • Receptors, Cell Surface / chemistry
  • Serum Albumin, Bovine / chemistry


  • Biomarkers
  • Carrier Proteins
  • Folate Receptors, GPI-Anchored
  • Receptors, Cell Surface
  • Serum Albumin, Bovine