A miniature chip for protein detection based on magnetic relaxation switches

A miniature multi-sample chip for protein detection with a bench-top magnetic resonance imager was created on the basis of magnetic relaxation switches. The chip was assessed with two protein systems. Both qualitative and quantitative results for the target proteins were obtained by image analysis and relaxation time measurement, respectively. The detection of prostate specific antigen, the serum marker of human prostate cancer, showed a linear concentration range of 17.3–43.2 ng mL−1 and a detection limit of 13.7 ng mL−1. As proof of concept, the analysis of 18 samples with a volume of 6.37 μL each was completed in 26 min by this chip. This technique may become an easy and efficient approach for rapid and high-throughput protein assay and protein–protein interaction screening.