Magnetically promoted rapid immunoreactions using functionalized fluorescent magnetic beads: a proof of principle.
BACKGROUND
Accurate detection and monitoring of disease-related biomarkers is important in understanding pathophysiology. We devised a rapid immunoreaction system that uses submicrometer polymer-coated fluorescent ferrite (FF) beads containing both ferrites (magnetic iron oxide) and fluorescent europium complexes.


METHODS
FF beads were prepared by encapsulation of hydrophobic europium complexes into the polymer layers of affinity magnetic beads using organic solvent. A sandwich immunoassay using magnetic collection of antibody-coated FF beads to a specific place was performed. Brain natriuretic peptide and prostate-specific antigen were selected as target detection antigens to demonstrate the feasibility of this approach. An immunohistochemical staining using magnetic collection of antibody-coated FF beads onto carcinoma cell samples was also performed.


RESULTS
The sandwich immunoassays, taking advantage of the magnetic collection of antibody-coated FF beads, detected target antigens within 5 min of sample addition. Without magnetic collection, the sandwich immunoassay using antibody-coated FF beads required long times, similar to conventional immunoassays. Using the magnetic collection of antibody-coated FF beads, immunohistochemical staining enabled discrimination of carcinoma cells within 20 min.


CONCLUSIONS
This proof of principle system demonstrates that immunoreactions involving the magnetic collection of antibody-coated FF beads allow acceleration of the antigen-antibody reaction. The simple magnetic collection of antibody-coated FF beads to a specific space enables rapid detection of disease-related biomarkers and identification of carcinoma cells.
Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan;
Satoshi
S
Sakamoto
Kenshi
K
Omagari
Yoshinori
Y
Kita
Yusuke
Y
Mochizuki
Yasuyuki
Y
Naito
Shintaro
S
Kawata
Sachiko
S
Matsuda
Osamu
O
Itano
Hiromitsu
H
Jinno
Hiroya
H
Takeuchi
Yuki
Y
Yamaguchi
Yuko
Y
Kitagawa
Hiroshi
H
Handa
D015415:Biomarkers / Q000032:analysis; D001943:Breast Neoplasms / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000378:metabolism; D045744:Cell Line, Tumor; D056831:Coordination Complexes / Q000737:chemistry*; D066246:ErbB Receptors / Q000378:metabolism; D004938:Esophageal Neoplasms / Q000378:metabolism; D005063:Europium; D005260:Female; D005290:Ferric Compounds / Q000737:chemistry*; D005456:Fluorescent Dyes; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008175:Lung Neoplasms / Q000378:metabolism; D059346:Magnets; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000032:analysis; D017430:Prostate-Specific Antigen / Q000032:analysis; D055752:Small Cell Lung Carcinoma / Q000378:metabolism
D015415:Biomarkers; D056831:Coordination Complexes; D005290:Ferric Compounds; D005456:Fluorescent Dyes; D020097:Natriuretic Peptide, Brain; C001215:ferrite; D005063:Europium; D066246:ErbB Receptors; D017430:Prostate-Specific Antigen