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Measurement of cardiac troponin I (cTnI) should be feasible for point-of-care testing (POCT) to diagnose acute myocardial infarction (AMI). Lateral flow immunoassays (LFIAs) have been long implemented in POCT and clinical settings. However, sensitivity, matrix effect and quantitation in lateral flow immunoassays (LFIAs) have been major limiting factors. The performance of LFIAs can be improved with upconverting nanoparticle (UCNP) reporters. Here we report a new methodological approach to quantify cTnI using UCNP-LFIA technology with minimized plasma interference. The performance of the developed UCNP-LFIA was evaluated using clinical plasma samples (n = 262). The developed UCNP-LFIA was compared to two reference assays, the Siemens Advia Centaur assay and an in-house well-based cTnI assay. By introducing an anti-IgM scrub line and dried EDTA in the LFIA strip, the detection of cTnI in plasma samples was fully recovered. The UCNP-LFIA was able to quantify cTnI concentrations in patient samples within the range of 30-10,000 ng/L. The LoB and LoD of the UCNP-LFIA were 8.4 ng/L and 30 ng/L. The method comparisons showed good correlation (Spearman's correlation 0.956 and 0.949, p < 0.0001). The developed UCNP-LFIA had LoD suitable for ruling in AMI in patients with elevated cTnI levels and was able to quantify cTnI concentrations in patient samples. The technology has potential to provide simple and rapid assay for POCT in ED setting., (© 2021. The Author(s).)

Cancer antigen 125 (CA125) is a widely used biomarker in monitoring of epithelial ovarian cancer (EOC). Due to insufficient cancer specificity of CA125, its diagnostic use is severely compromised. Abnormal glycosylation of CA125 is a unique feature of ovarian cancer cells and could improve differential diagnosis of the disease. Here we describe the development of a quantitative lateral flow immunoassay (LFIA) of aberrantly glycosylated CA125 which is widely superior to the conventional CA125 immunoassay (CA125IA). With a 30 min read-out time, the LFIA showed 72% sensitivity, at 98% specificity using diagnostically challenging samples with marginally elevated CA125 (35-200 U/mL), in comparison to 16% sensitivity with the CA125IA. We envision the clinical use of the developed LFIA to be based on the substantially enhanced disease specificity against the many benign conditions confounding the diagnostic evaluation and against other cancers.

Background: Among the Alzheimer's disease (AD) biomarkers measured in blood, phosphorylated forms of tau (p-tau) have been shown to exhibit a particularly high diagnostic potential. Here, we performed a comprehensive method comparison study, followed by evaluation of the diagnostic performance of eight recent plasma p-tau immunoassays targeting different tau phosphorylation sites, different tau fragments, and that are measured by two distinct platforms. Methods: We enrolled a cohort of 40 patients with AD at the stage of dementia (AD-dem) characterized by positive CSF A + T + profile, and a control group of 40 cognitively healthy participants (Control), to conduct a comprehensive method comparison for three plasma p-tau181 and five plasma p-tau217 assays run on the Simoa® HD-X™ or Lumipulse® G600II/G1200 platforms. Design of the compared assays differed in regard to: (1) tau phosphorylation site targeted by the capture antibody (T181 or T217), and (2) epitope of the pan-tau detector antibody (N-terminal or mid-region). For each of the assays we determined precision and analytical sensitivity parameters and used Passing-Bablok regression and Bland-Altman plots for pairwise comparison of p-tau181 or p-tau217 assays. Subsequently, we evaluated the diagnostic accuracy of all the assays for discrimination between AD-dem and Control groups. Results: We found a strong, positive correlation between all the measurements. Fixed and/or proportional bias was observed for each of compared p-tau181 assay pairs or p-tau217 assay pairs. While both plasma p-tau181 and p-tau217 levels were significantly increased in AD-dem vs. Control groups as measured by all assays, higher median concentration AD-dem/Control fold change and AUC values were observed for p-tau217 (assays range: fold change 3.72–6.74, AUC 0.916–0.956) compared with p-tau181 (assays range 1.81–2.94, AUC 0.829–0.909), independently of the platform used. No significant differences were observed between diagnostic performance of p-tau181 assays or p-tau217 assays targeting tau N-terminus or mid-region. Conclusions: Although all plasma p-tau measurements enabled discrimination between clinical groups, p-tau217 assays showed the highest robustness, independently of the pan-tau detector antibody targeting N-terminal or mid-region, and independently of the platform used. Considering the observed method disagreement in measured absolute concentrations, we stress the need for development of certified reference material, harmonizing measurements across different platforms. [ABSTRACT FROM AUTHOR]

Rapid diagnostic tests (RDTs) are often used for the detection of anti-human immunodeficiency virus (HIV) antibodies in remote locations in low- and middle-income countries (LMIC) with low or limited access to central laboratories. The typical format of an RDT is a lateral flow assay (LFA) with visual interpretation prone to subjectivity. This risk of misinterpretation can be overcome with luminescent upconverting nanoparticle reporters (UCNPs) measured with a miniaturized easy-to-use reader instrument. An LFA with UCNPs for anti-HIV-1/2 antibodies was developed and the assay performance was evaluated extensively with challenging patient sample panels. Sensitivity (n = 145) of the UCNP-LFA was 96.6% (95% CI: 92.1–98.8%) and specificity (n = 309) was 98.7% (95% CI: 96.7–99.7%). Another set of samples (n = 200) was used for a comparison between the UCNP-LFA and a conventional visual RDT. In this comparison, the sensitivities for HIV-1 were 96.4% (95% CI: 89.8–99.3%) and 97.6% (95% CI: 91.6–99.7%), for the UCNP-LFA and conventional RDT, respectively. The specificity was 100% (95% CI: 96.4–100%) for both assays. The developed UCNP-LFA demonstrates the applicability of UCNPs for the detection of anti-HIV antibodies. The signal measurement is done by a reader instrument, which may facilitate automated result interpretation, archiving and transfer of data from de-centralized locations. [ABSTRACT FROM AUTHOR]