Background Long cardiac troponin T (cTnT) has been proposed to be a promising and more specific biomarker of acute myocardial infarction (AMI). As it represents a subfraction of circulating cTnT, detection of very low concentrations is a requirement. The aim of this study was to develop a novel, highly sensitive immunoassay for long cTnT. Methods A two-step sandwich-type immunoassay for long cTnT was developed, utilizing upconverting nanoparticles (UCNPs) as reporters. The limits of detection and quantitation were determined for the assay. Linearity and matrix effects were evaluated. Performance with clinical samples was assessed with samples from patients with non-ST elevation myocardial infarction (NSTEMI, n = 30) and end-stage renal disease (ESRD, n = 37) and compared to a previously developed time-resolved fluorescence (TRF)-based long cTnT assay and a commercial high-sensitivity cTnT assay. Results The novel assay reached a 28-fold lower limit of detection (0.40 ng/L) and 14-fold lower limit of quantitation (1.79 ng/L) than the previously developed TRF long cTnT assay. Li-heparin and EDTA plasma, but not serum, were found to be suitable sample matrixes for the assay. In a receiver operating characteristics curve analysis, the troponin ratio (long/total cTnT) determined with the novel assay showed excellent discrimination between NSTEMI and ESRD with an area under the curve of 0.986 (95% CI, 0.967–1.000). Conclusions By utilizing upconversion luminescence technology, we developed a highly sensitive long cTnT assay. This novel assay can be a valuable tool for investigating the full potential of long cTnT as a biomarker for AMI. ClinicalTrials.gov Registration Number: NCT04465591

中文翻译：

---

使用上转换发光对长形式心肌肌钙蛋白 T 进行高灵敏度免疫测定


背景 长心肌肌钙蛋白 T （cTnT） 已被提出是急性心肌梗死 （AMI） 的一种有前途且更具特异性的生物标志物。由于它代表循环 cTnT 的一个亚级，因此需要检测非常低的浓度。本研究的目的是开发一种针对长 cTnT 的新型、高灵敏度免疫测定法。方法 利用上转换纳米颗粒 （UCNP） 作为报告基因，开发了一种针对长 cTnT 的两步夹心型免疫测定法。测定测定的检测和定量限。评估了线性和基质效应。使用非 ST 段抬高型心肌梗死 （NSTEMI， n = 30） 和终末期肾病 （ESRD， n = 37） 患者的样本评估临床样本的性能，并与先前开发的基于时间分辨荧光 （TRF） 的长 cTnT 测定和市售高敏 cTnT 测定进行比较。结果 与先前开发的 TRF 长 cTnT 检测相比，该检测方法的检测下限 （0.40 ng/L） 和 14 倍的定量下限 （1.79 ng/L） 分别达到了 28 倍和 14 倍。发现肝素和 EDTA 血浆（而不是血清）是适合测定的样品基质。在受试者工作特征曲线分析中，用新测定法测定的肌钙蛋白比值 （长/总 cTnT） 显示 NSTEMI 和 ESRD 之间有很好的区分力，曲线下面积为 0.986 （95% CI，0.967-1.000）。结论 利用上转换发光技术，我们开发了一种高灵敏度的长 cTnT 测定法。这种新颖的测定法可以成为研究长 cTnT 作为 AMI 生物标志物的全部潜力的宝贵工具。ClinicalTrials.gov 注册号：NCT04465591