Fast and ultrafast thermal contrast amplification of gold nanoparticle-based immunoassays

Yilin Liu, Li Zhan, Joseph Kangas, Yiru Wang, John Bischof

Research output: Contribution to journalArticlepeer-review


For highly sensitive point-of-care (POC) diagnostics, we explored the limit of thermal contrast amplification (TCA) reading of gold nanoparticles (GNPs/mm2) at test regions in immunoassays. More specifically, we built and compared fast (minute scale) and ultrafast (seconds scale) TCA setups using continuous-wave (CW) and ms pulsed lasers, respectively. TCA improved the limit of detection (LoD) for silica-core gold nanoshells (GNSs) preloaded in nitrocellulose (NC) membrane as model lateral flow immunoassays (LFAs) by 10- to 20-fold over visual reading. While the ultrafast TCA led to higher thermal signals, this came with a twofold loss in LoD vs. fast TCA primarily due to noise within the infrared sensor and a necessity to limit power to avoid burning. To allow higher laser power, and therefore amplification fold, we also explored transparent glass coverslip substrate as a model microfluidic immunoassay (MIA). We found the ultrafast TCA reading of GNS-coated coverslips achieved a maximal signal amplification (57-fold) over visual reading of model LFAs. Therefore, ultrafast TCA-MIA is promising for ultrasensitive and ultrafast diagnostics. Further advantages of using TCA in MIA vs. LFA could include lower sample volume, multiplexed tests, higher throughput, and fast reading. In summary, TCA technology is able to enhance the sensitivity and speed of reading GNPs (GNPs/mm2) within both LFAs and MIAs.

Original languageEnglish (US)
Article number12729
JournalScientific reports
Issue number1
StatePublished - Dec 2022

Bibliographical note

Funding Information:
J.C.B. acknowledges the Kuhrmeyer Chair in Mechanical Engineering and the Medtronic-Bakken Endowed Chair for Engineering in Medicine. We thank nanoComposix, Inc. for providing silica-cored gold nanoshells to our lab.

Publisher Copyright:
© 2022, The Author(s).


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