Rapid Distance-Based Cardiac Troponin Quantification Using Paper Analytical Devices for the Screening and the Follow-Up of Acute Myocardial Infarction, Using a Single Drop of Human Whole Blood

Abstract

This work introduces the procedure of using nonimmunoassay distance-based paper analytical devices (dPADs) to accurately measure any traces of the cardiac troponin I (TnI) in whole blood samples without the use of any external blood separation. This enables a rapid clinical diagnosis and the subsequent follow-up in regard to identifying acute myocardial infarction. These dPADs are designed and constructed to accommodate three parts: (1) a blood separation zone that is immobilized with a hemostatic agent, this no longer requires a blood separation membrane for the isolation of the plasma from the blood element, (2) a pretreatment zone, and (3) a detection zone coated with thymol blue. The quantitative TnI level in the whole blood was determined by measuring the blue color length found in the detection zone, which is proportional to the concentration, owing to the dry protein binding principle. Correspondingly, a mere single drop of human whole blood performs adequately within our proposed method. This reduces both the size of the collection process and the sample volumes needed in the respective medical fields. As we cover all of the optimization studies, our dPADs provide an evaluation of the linearity range from 0.025 to 2.5 ng/mL (R 2 = 0.9989) of TnI, with a detection limit as low as 0.025 ng/mL by use of an observation just using the naked eye. To validate the clinical utilities of our proposed method, our dPADs were then applied for the detection of TnI in humans using the whole blood sample of 15 volunteers. A great amount of accuracy was required in this assay because there was no significant difference between both methods, with the confidence level being as high as 95%. This technique also showed that the recoveries ranged from 99.40 to 104.27%, with the highest relative standard deviation being at 3.77%. Thus, our proposed dPADs offer more benefits for a rapid TnI determination.

Distance-based β-amyloid protein detection on PADs for the scanning and subsequent follow-up of Alzheimer's disease in human urine samples

“…Nevertheless, it could not interfere with the Aβ detection using this assay due to its small molecule, thus affecting its low positive charge and hydrophobic capacity. 32 Furthermore, we detected the signals of mixtures of Aβ protein and the interferents at the above-concentration, as indicated in Fig. 4(b).…”

“…Our results indicated that the color change from yellow to blue along the distance length of the paper was directly proportional to the TnI level, with both high sensitivity and selectivity, with a detection limit equal of 0.025 ng mL −1 . 32 According to this, it can be noticed that there were no interferences in the analysis, because TnI has a pI of 9.86, which is higher than that of most of the general proteins. Also, the high dissociation constant (p K a ) is 8.6 in the buffer solution at pH 8.0.…”

“…Our proposed sensor was deposited with citrate buffer solution (CBS) at pH 5.0 onto the sample zone to avoid the interference of leaked albumin or globulin proteins in urine samples, where both albumin and globulin protein have a pI of 4.7. 32 Then we coated bromocresol purple (BCP) onto the detection area to interact with the Aβ protein, thus illustrating a color change over a distance length from yellow to blue, which could be distinguished by the naked eye. Specially, the selectivity of this developed sensor was based on a satisfactory combination of an Aβ protein and the matrix samples.…”

Recent Advances and Applications in Paper-Based Devices for Point-of-Care Testing

“…3 d). In 2021, a non-immunoassay dPAD was introduced for the detection of cardiac troponin I (TnI) [ 142 ]. Without any external blood separation, TnI in whole blood samples was determined by using the dPAD with the LOD of 0.025 ng/mL.…”

Microsampling tools for collecting, processing, and storing blood at the point-of-care

“…Eliminating the void volume associated with a standard PSM layer for separation allowed lower volumes of blood to perform the same colorimetric assay. Similarly, a distance-based µPAD featured the same Whatman 1 filter paper with a wax patterned sample addition zone and lateral channel (40 mm x 2 mm) to yield a dried plasma output [127]. In this device, plasma separation was achieved by a hemostatic agent (3% w/v CaCO3/chitosan in 1 M acetic acid) stored in the sample addition zone, which induced clotting and blood aggregation by accelerating thrombin formation.…”