Communication pubs.acs.org/JACS
Plasmonic Photothermal Gold Bipyramid Nanoreactors for Ultrafast Real-Time Bioassays Jung-Hoon Lee,† Zoya Cheglakov,† Jaeseok Yi,‡ Timothy M. Cronin,† Kyle J. Gibson,† Bozhi Tian,†,‡,§ and Yossi Weizmann*,† †
Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States § The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States ‡
S Supporting Information *
development of mobile, point-of-care, and high-throughput analytics because it eliminates the need for gel electrophoresis or other postamplification processes.8 Therefore, there is a critical need to provide new nanotechnologies to address these clear limitations in the current methodologies and to improve detection time, mobility, and the cost- and energy-efficiency of these important biochemical and medical assays while retaining real-time capabilities. Our PPT-NAAs are based on the light-driven photothermal heating of gold bipyramid nanoparticles (AuBPs), which are evenly dispersed in the reaction mixture in a typical PCR tube (Figures 1 and S1). When the reaction solution containing the DNA target and AuBPs is exposed to the IR-light-emitting diodes (IR-LED), the AuBPs act as nanoreactors to absorb the photonic energy and convert it to heat energy, rapidly increasing the temperature of the solution.7,9 In addition, constant and discrete temperatures for isothermal or thermocycling amplification can be achieved by pulsing the IR-LED. During the annealing or extension phase, the accumulated products are measured as a function of the fluorescence emitted from intercalating dyes commonly used for PCR, which are excited by the blue LED and detected via a spectrophotometer. Upon absorbance of a photon, there are no significant energy loss pathways other than the heat dissipation for gold nanoparticles.10 Even and uniform heating throughout the solution is necessary to achieve homogeneity of the reaction; therefore, nanoparticles with a low polydispersity in size and shape, narrow absorbance line width, and a high extinction coefficient would provide an optimal PPT response. AuBPs, having a highly tunable longitudinal surface plasmon resonance (LSPR) and a polydispersity of
