前列腺癌的早期诊断对于成功治疗以及显着改善预后至关重要。在实验室实践中，标准的非侵入性诊断方法是相关生物标志物前列腺特异性抗原（PSA）的免疫化学检测。 PSA 的超灵敏检测对于诊断和复发监测至关重要。为了实现卓越的灵敏度，我们开发了一种带有流通池的微流体装置，用于使用光子上转换纳米颗粒 (UCNP) 作为检测标签进行单分子分析。为此，首先针对 PSA 的捕获和预浓缩对磁性微粒 (MB) 进行优化，然后用于在微流体装置中实施基于珠子的上转换联免疫测定 (ULISA)。基于对 MB 上单个纳米颗粒标记的 PSA 分子进行计数的数字读数使 50% 胎牛血清中的检测限达到 1.04 pg mL-1 (36 fM)，这比相应的基于模拟 MB 的 ULISA 提高了 11 倍。微流控技术还具有其他一些优点，例如易于实施和实现高通量分析的潜力。最后，证明微流控装置适用于临床样品分析，与参考电化学发光测定具有良好的相关性（回收率在 97% 至 105% 之间）。

Early-stage diagnosis of prostatic carcinoma is essential for successful treatment and, thus, significant prognosis improvement. In laboratory practice, the standard non-invasive diagnostic approach is the immunochemical detection of the associated biomarker, prostate-specific antigen (PSA). Ultrasensitive detection of PSA is essential for both diagnostic and recurrence monitoring purposes. To achieve exceptional sensitivity, we have developed a microfluidic device with a flow-through cell for single-molecule analysis using photon-upconversion nanoparticles (UCNPs) as a detection label. For this purpose, magnetic microparticles (MBs) were first optimized for the capture and preconcentration of PSA and then used to implement a bead-based upconversion-linked immunoassay (ULISA) in the microfluidic device. The digital readout based on counting single nanoparticle-labeled PSA molecules on MBs enabled a detection limit of 1.04 pg mL-1 (36 fM) in 50% fetal bovine serum, which is an 11-fold improvement over the respective analog MB-based ULISA. The microfluidic technique conferred several other advantages, such as easy implementation and the potential for achieving high-throughput analysis. Finally, it was proven that the microfluidic setup is suitable for clinical sample analysis, showing a good correlation with a reference electrochemiluminescence assay (recovery rates between 97% and 105%).