A Cellulose Paper-Based Fluorescent Lateral Flow Immunoassay for the Quantitative Detection of Cardiac Troponin I

Abstract

This paper presents a lateral flow assay (LFA) for the quantitative, fluorescence-based detection of the cardiac biomarker troponin I (cTnI) that features an analytical strip made of cellulose filter paper. The results show that the wicking and test time are comparable to those obtained with conventional nitrocellulose (NC)-based LFAs. Further, the cellulose paper provides an excellent background with no auto-fluorescence that is very adequate in detecting fluorescent lines. While fluorescence that was generated with cellulose strips was lower when compared to that generated in NC strips, signals could be improved by layering carbon nanofibers (CNF) on the cellulose. A nonlinear behavior of the concentration–response relationship was observed for the LFA architectures with NC, cellulose, and cellulose-CNF in the 0 to 200 ng/mL cTnI concentration range. The measurements were consistent and characterized by coefficients of variation lower than 2.5%. Detection and quantitation limits that were in the range 1.28–1.40 ng/mL and 2.10–2.75 ng/mL were obtained for LFA with cellulose and cellulose CNF strips that are equivalent to the limits obtained with the standard NC LFA. Overall, we showed that commercially available filter paper can be used in the analytical strip of LFA.

Development of Liposome-Based Immunoassay for the Detection of Cardiac Troponin I

“…The limit of detection (LOD) of the assay was 6.5 ng/mL (determined as the minimum concentration of cTnI at which the mean (f − f 0 ) values over all replicates is larger than (f 0 ) by at least three standard deviations of the negative controls), which is very close the normal level (5 ng/mL) cut-off in a patient's blood. Although our results presented a higher value of LOD than the previously reported assays [2,24,[55][56][57], the assay was highly specific towards cTnI even in the presence of other interference proteins in the human serum and, more importantly, it has a wide linear dynamic range from right above the normal concentrations (LOD) of cTnI to 320 ng/mL.…”

Ten Years of Lateral Flow Immunoassay Technique Applications: Trends, Challenges and Future Perspectives

“…The use of biodegradable components could also be desirable, even if most of the LFIAs for professional use (in the clinical field) must be incinerated due to possible biohazard. Notwithstanding the exceptional properties of the nitrocellulose as solid support for the LFIA platform, researchers [ 291 , 292 , 293 ] are trying to replace its use with the cellulose that, in addition to further reducing costs, would have a reduced impact on the environment because its production process requires less chemicals in comparison to the nitrocellulose production. Most recently, promising results have been obtained by Adrian Elter et al that developed cellulose-based LFIAs [ 294 ].…”

Fluorescent Immunoassays for Detection and Quantification of Cardiac Troponin I: A Short Review

“…This enhances the sensitivity of this sandwich immunoassay for visual detection of the fluorescent signal. However, the LDR of 2.10-2.75 ng/mL renders the assay technically not useful for practical applications in clinical settings [43].…”