Ultrasensitive and fast detection of pathogens using Europium-containing polystyrene nanospheres in a homemade portable NMR diagnostic system

Abstract

The use of nuclear magnetic resonance (NMR) platforms to detect biological samples via magnetic nanoparticles has shown great importance in clinical applications. In numerous studies, superparamagnetic nanoparticles, including ferromagnetic nanoparticles, have been adopted to improve the performance of magnetic nanoparticles. Here we developed a simple and novel europium (Eu)-containing polystyrene nanosphere (PS NS)-based NMR system for rapid pathogen detection in clinical samples. Using this proposed portable NMR diagnostic system, we found that during pathogen detection, NPs with lower susceptibility (e.g., Eu-containing PS NSs) produced an unexpected detection effect compared with iron oxide NPs. Our Eu-containing PS NS-based NMR diagnostic system showed higher detection sensitivity, broader detection range, and higher stability than conventional iron oxide NP-based NMR platforms do. Using an inexpensive microcontact-printed Ag microcoil-based NMR probe, we demonstrated unprecedented detection sensitivity and speed with minimal sample preparation for pathogen analyses. The sample concentration of 0.2 ng/mL of hepatitis B virus surface antigen (HBsAg) and 10 CFU/mL of Clostridium difficile can be attained by the NMR diagnostic system within 5 s, and concentration-detection ranges spanned over three orders of magnitude. With advantages of low-cost NMR probe, a portable instrument, and convenient operation, our proposed NMR platform may provide a promising point-of-care diagnostic system in clinical applications.