This paper presents integrated nanorod arrays on microfluidic chips for fast and sensitive flow-through immunoassays. Dense arrays of Au nanorods are fabricated through one-step oblique angle deposition, eliminating the need for advanced lithography. The plasmonic structure improves the cardiac troponin I (cTnl) assay detection limit by over 6 × 10⁵-fold, reaching 33.9 fg mL⁻¹ (~1.4 fM). Monolithic integration with microfluidic elements enables a flow-through assay for quantitative cTnl detection in serum with a sensitivity of 6.9 pg mL⁻¹ (~0.3 pM) in <6 min. This sensitivity is attributed to the large surface area for antibody conjugation and metal-enhanced fluorescent signals. Simultaneous detection of multiple cancer biomarkers (PSA and CEA) is also demonstrated. The simple fabrication process makes this device suitable for point-of-care diagnosis.

Ye Wang, Jiongdong Zhao, Yu Zhu, Shurong Dong, Yang Liu, Yijun Sun, Liling Qian, Wenting Yang, Zhen Cao