One-step detection of pathogens and viruses: combining magnetic relaxation switching and magnetic separation.
We report a sensing methodology that combines magnetic separation (MS) and magnetic relaxation switching (MS-MRS) for one-step detection of bacteria and viruses with high sensitivity and reproducibility. We first employ a magnetic field of 0.01 T to separate the magnetic beads of large size (250 nm in diameter) from those of small size (30 nm in diameter) and use the transverse relaxation time (T2) of the water molecules around the 30 nm magnetic beads (MB30) as the signal readout of the immunoassay. An MS-MRS sensor integrates target enrichment, extraction, and detection into one step, and the entire immunoassay can be completed within 30 min. Compared with a traditional MRS sensor, an MS-MRS sensor shows enhanced sensitivity, better reproducibility, and convenient operation, thus providing a promising platform for point-of-care testing.
†Beijing Engineering Research Center for BioNanotechnology and CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for NanoScience and Technology, Beijing, 100190, China.
Yiping
Y
Chen
†Beijing Engineering Research Center for BioNanotechnology and CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for NanoScience and Technology, Beijing, 100190, China.
Yunlei
Y
Xianyu
§Beijing Institute for Tropical Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yongan Road, Xicheng District, Beijing, 100050, China.
Yu
Y
Wang
†Beijing Engineering Research Center for BioNanotechnology and CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for NanoScience and Technology, Beijing, 100190, China.
Xiaoqing
X
Zhang
†Beijing Engineering Research Center for BioNanotechnology and CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for NanoScience and Technology, Beijing, 100190, China.
Ruitao
R
Cha
†Beijing Engineering Research Center for BioNanotechnology and CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for NanoScience and Technology, Beijing, 100190, China.
Jiashu
J
Sun
†Beijing Engineering Research Center for BioNanotechnology and CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for NanoScience and Technology, Beijing, 100190, China.
Xingyu
X
Jiang
D000818:Animals; D001419:Bacteria / Q000302:isolation & purification*; D015374:Biosensing Techniques / Q000379:methods*; D007118:Immunoassay / Q000379:methods*; D060526:Magnetic Fields; D059346:Magnets / Q000737:chemistry; D008863:Microspheres; D008892:Milk / Q000382:microbiology; D009522:Newcastle disease virus / Q000302:isolation & purification; D015203:Reproducibility of Results; D014780:Viruses / Q000302:isolation & purification*
homogeneous immunosensor; magnetic bead; magnetic relaxation switch; magnetic separation; one-step detection