Visual detection of nucleic acids based on Mie scattering and the magnetophoretic effect.
Visual detection of nucleic acid biomarkers is a simple and convenient approach to point-of-care applications. However, issues of sensitivity and the handling of complex bio-fluids have posed challenges. Here we report on a visual method detecting nucleic acids using Mie scattering of polystyrene microparticles and the magnetophoretic effect. Magnetic microparticles (MMPs) and polystyrene microparticles (PMPs) were surface-functionalised with oligonucleotide probes, which can hybridise with target oligonucleotides in juxtaposition and lead to the formation of MMPs-targets-PMPs sandwich structures. Using an externally applied magnetic field, the magnetophoretic effect attracts the sandwich structure to the sidewall, which reduces the suspended PMPs and leads to a change in the light transmission via the Mie scattering. Based on the high extinction coefficient of the Mie scattering (∼3 orders of magnitude greater than that of the commonly used gold nanoparticles), our results showed the limit of detection to be 4 pM using a UV-Vis spectrometer or 10 pM by direct visual inspection. Meanwhile, we also demonstrated that this method is compatible with multiplex assays and detection in complex bio-fluids, such as whole blood or a pool of nucleic acids, without purification in advance. With a simplified operation procedure, low instrumentation requirement, high sensitivity and compatibility with complex bio-fluids, this method provides an ideal solution for visual detection of nucleic acids in resource-limited settings.
Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong Special Administrative Region, China. thchen@cityu.edu.hk.
Zichen
Z
Zhao
Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong Special Administrative Region, China. thchen@cityu.edu.hk.
Shan
S
Chen
Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong Special Administrative Region, China. thchen@cityu.edu.hk.
John Kin Lim
JK
Ho
Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong Special Administrative Region, China. thchen@cityu.edu.hk.
Ching-Chang
CC
Chieng
Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong Special Administrative Region, China. thchen@cityu.edu.hk and School of Creative Media, City University of Hong Kong, Hong Kong Special Administrative Region, China.
Ting-Hsuan
TH
Chen
D000818:Animals; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D004396:Coloring Agents / Q000737:chemistry; D008280:Magnetics; D053758:Nanoparticles / Q000737:chemistry; D009696:Nucleic Acids / Q000032:analysis* / Q000097:blood; D020641:Polymorphism, Single Nucleotide; D011137:Polystyrenes / Q000737:chemistry
D004396:Coloring Agents; D009696:Nucleic Acids; D011137:Polystyrenes