Biomarker Quantification in Unprocessed Human Sera by Using A New Nanomagnetic Protein Assay

Abstract

Large hysteretic magnetoresistance in high-mobility semiconductor quantum wires bridged by single-domain nanomagnets Appl. Phys. Lett. 91, 022105 (2007); 10.1063/1.2756270Resonant microwave power absorption and relaxation of the energy levels of the molecular nanomagnet Fe 8 using superconducting quantum interference device-based magnetometry Appl. Phys. Lett.Abstract. Early recognition and prevention of chronic disease, such as lung cancer, require a fast, accurate detection and longitudinal monitoring on potential biomarkers, which could identify the molecule change in the initial stage of the chronic disease. Here we report the realization of specific and accurate quantification of a low-abundance serum protein in unprocessed human sera, using our novel giant magnetoresistive (GMR) biosensing system with uniform highmagnetic-moment nanoparticles and a competition based detection scheme. Only one antibody is needed for such detection scheme. The quantification of interleukin-6 (IL-6, a low-abundance protein and a potential cancer biomarker), as low as 125 fM IL-6 proteins, directly in 4 μL of unprocessed human sera was demonstrated within 5 minutes by such system. The results nicely differentiate normal individuals and lung cancer patients. This platform has great potential to facilitate the identification and validation of disease biomarkers.