Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
Sci Rep. 2022 Jul 26;12(1):12729. doi: 10.1038/s41598-022-14841-3.
For highly sensitive point-of-care (POC) diagnostics, we explored the limit of thermal contrast amplification (TCA) reading of gold nanoparticles (GNPs/mm) 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/mm) within both LFAs and MIAs.
对于高灵敏度的即时检测（POC）诊断，我们探索了在免疫分析中测试区域内金纳米颗粒（GNPs/mm）的热对比度放大（TCA）读数的极限。更具体地说，我们分别使用连续波（CW）和毫秒脉冲激光器构建并比较了快速（分钟级）和超快速（秒级）TCA 装置。TCA 提高了载于硝酸纤维素（NC）膜中的硅芯金纳米壳（GNS）作为侧向流动免疫分析（LFA）模型的检测限（LoD），比目视读数提高了 10 到 20 倍。虽然超快速 TCA 产生了更高的热信号，但与快速 TCA 相比，LoD 降低了两倍，这主要是由于红外传感器内的噪声以及为避免燃烧而必须限制功率。为了允许更高的激光功率，从而实现更高的放大倍数，我们还探索了透明玻璃盖玻片作为模型微流控免疫分析（MIA）的基底。我们发现，经过 GNS 涂层的盖玻片的超快速 TCA 读数比模型 LFA 的目视读数实现了高达 57 倍的信号放大。因此，超快速 TCA-MIA 有望实现超灵敏和超快速诊断。与 LFA 相比，TCA 在 MIA 中的进一步优势可能包括更低的样品体积、多重测试、更高的通量和快速读数。总之，TCA 技术能够提高 LFA 和 MIA 中 GNPs（GNPs/mm）的灵敏度和读数速度。
