Qualitative bedside assay of increased human serum myoglobin by sandwich dot-immunogold filtration for the diagnosis of acute myocardial infarction

A Dual-Label Time-Resolved Fluorescence Immunoassay for the Simultaneous Determination of Cardiac Troponin T and Myoglobin

The aim of this study was to establish a dual-label time-resolved fluorescence immunoassay (TRFIA) for the simultaneous determination of cardiac troponin T (cTnT) and myoglobin (MYO) for the early diagnosis of acute myocardial infarction. The sandwich immunoassay was used to detect the concentration of cTnT and MYO in serum. cTnT and MYO in serum were captured by anti-cTnT and anti-MYO antibodies immobilized on microtiter wells and then banded together with another anti-cTnT and anti-MYO labeled with europium(III) Sm³⁺ and samarium(III) Eu³⁺ chelates, followed by fluorescence measurement using time-resolved fluorometry. The performance of this TRFIA was evaluated using the clinical serum and compared with the commercial assays. The linear correlation coefficients ( R²) of the cTnT and MYO standard curves were 0.9993 and 0.9995, respectively. The sensitivity for cTnT detection was 2.21 pg/mL (linear dynamic range was 3.24-963.71 pg/mL), and the average recovery was 100.57%. The sensitivity for MYO detection was 3.24 ng/mL (linear dynamic range was 4.95-976.85 ng/mL), and the average recovery was 99.79%. High correlation coefficients ( R²) were obtained between the commercial assays and dual-label TRFIA ( R² = 0.999). The present dual-label TRFIA has high sensitivity, specificity, and accuracy in clinical sample analysis. It is a good alternative to the single-label diagnostic methods.

Dot immunogold filtration assay (DIGFA) for the rapid detection of specific antibodies against the rat lungworm Angiostrongylus cantonensis (Nematoda: Metastrongyloidea) using purified 31-kDa antigen

A rapid dot immunogold filtration assay (DIGFA) was adopted for specific immunodiagnosis of human cerebral angiostrongyliasis, using purified 31-kDa glycoprotein specific to Angiostrongylus cantonensis as diagnostic antigen and protein A colloidal gold conjugate as antigen-antibody detector. A total of 59 serum samples were assayed - 11 samples from clinically diagnosed patients with detectable A. cantonensis-specific antibody in immunoblotting; 23 samples from patients with other related parasitic diseases, i.e. gnathostomiasis (n= 8), cysticercosis (n= 5), toxocariasis (n= 2), filariasis (n= 4), paragonimiasis (n= 2) and malaria (n= 2); and 25 samples from normal healthy subjects. The sensitivity and specificity of DIGFA to detect anti-A. cantonensis specific antibodies in serologically confirmed angiostrongyliasis cases, were both 100%. No positive DIGFA was observed in cases with other parasitic diseases, and the healthy control subjects. The 3-min DIGFA is as sensitive and specific as the 3-h immunoblot test in angiostrongyliasis confirmed cases that revealed a 31-kDa reactive band. The gold-based DIGFA is more rapid and easier to perform than the traditional enzyme-linked immunosorbent assay (ELISA). The test utilizing purified A. cantonensis antigen is reliable and reproducible for specific immunodiagnosis of human infection with A. cantonensis - thus can be applied as an additional routine test for clinical diagnostic support. Large-scale sero-epidemiological studies in endemic communities in north-east Thailand are under way to evaluate its usefulness under field conditions.

Modeling of dielectrophoretic transport of myoglobin molecules in microchannels

Myoglobin is one of the premature identifying cardiac markers, whose concentration increases from 90 pgml or less to over 250 ngml in the blood serum of human beings after minor heart attack. Separation, detection, and quantification of myoglobin play a vital role in revealing the cardiac arrest in advance, which is the challenging part of ongoing research. In the present work, one of the electrokinetic approaches, i.e., dielectrophoresis (DEP), is chosen to separate the myoglobin. A mathematical model is developed for simulating dielectrophoretic behavior of a myoglobin molecule in a microchannel to provide a theoretical basis for the above application. This model is based on the introduction of a dielectrophoretic force and a dielectric myoglobin model. A dielectric myoglobin model is developed by approximating the shape of the myoglobin molecule as sphere, oblate, and prolate spheroids. A generalized theoretical expression for the dielectrophoretic force acting on respective shapes of the molecule is derived. The microchannel considered for analysis has an array of parallel rectangular electrodes at the bottom surface. The potential and electric field distributions are calculated using Green's theorem method and finite element method. These results also compared to the Fourier series method, closed form solutions by Morgan et al. [J. Phys. D: Appl. Phys. 34, 1553 (2001)] and Chang et al. [J. Phys. D: Appl. Phys. 36, 3073 (2003)]. It is observed that both Green's theorem based analytical solution and finite element based numerical solution for proposed model are closely matched for electric field and square electric field gradients. The crossover frequency is obtained as 40 MHz for given properties of myoglobin and for all approximated shapes of myoglobin molecule. The effect of conductivity of medium and myoglobin on the crossover frequency is also demonstrated. Further, the effect of hydration layer on the crossover frequency of myoglobin molecules is also presented. Both positive and negative DEP effects on myoglobin molecules are obtained by switching the frequency of applied electric field. The effect of different shapes of myoglobin on DEP force is studied and no significant effect on DEP force is observed. Finally, repulsion of myoglobin molecules from the electrode plane at 1 KHz frequency and 10 V applied voltage is observed. These results provide the ability of applying DEP force for manipulating nanosized biomolecules such as myoglobin.