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CRP Assay Comparison
 The C-reactive protein (CRP) assay was one of the first immunoassays implemented on the Electronic Taste Chip (ETC) system. Since its inception, the CRP assay has been thoroughly optimized and now outperforms the counterpart assays of other established methodologies. The table below outlines the accolades of the ETC CRP assay relative to traditional testing protocols.
Organization |
Methodology |
Useful
Assay Range |
Limit of Detection |
Intra assay
% CV |
Inter-Assay
% CV |
UT ETC |
Lab-on-a-chip |
In PBS: 20 fg/mL -100,000 ng/mL
In Saliva: 10- 10,000 pg/mL
In Serum: 0.2 - 100,000 ng/mL |
10.0 fg/mL
1 pg/mL
0.1 ng/mL
|
8%
|
3 - 10% |
ALPCO |
ELISA |
1.9 - 150 ng/mL |
0.124 ng/mL |
6% |
12% |
Diagnostic Systems Laboratories |
ELISA |
10 - 500 ng/mL |
1.6 ng/mL |
3% |
5% |
Dade Behring |
IN |
175 - 11,000 ng/mL |
20.0 ng/mL |
N/A
|
4.3- 6.8% |
Wako |
IT |
50 - 10,000 ng/mL |
60.0 ng/mL |
N/A
|
1 - 11% |
Roche |
Particle-enhanced IT |
100 - 20,000 ng/mL |
210 ng/mL |
N/A
|
0.6 - 7.2 |
Abbot |
Latex enhanced IT
Micro-particle capture |
5000 -300,000 ng/mL
50 - 30,000 ng/mL (1 : 50 dilution) |
N/A
N/A |
N/A
N/A
|
11-12%
6.7 -12% |
Diagnostic Products Corporation |
IL |
100 - 250,000 ng/mL (1 : 100 dilution) |
20 ng/mL |
N/A
|
6.4 - 12% |
Beckman Coulter |
IN |
1,000 -960,000 ng/mL |
|
N/A
|
4-24% |
Iatron |
IT |
50 - 4000 ng/mL |
5 ng/mL |
N/A
|
1.1 - 3.4% |
Daiichi |
IT |
200 - 60,000 ng/mL |
40 ng/mL |
N/A
|
1.3 - 6.1% |
Denka |
IT |
50 - 10,000 ng/mL |
30 ng/mL |
N/A
|
2.2 - 5.1% |
Kamiya |
IT |
100 -20,000 ng/mL |
320 ng/mL |
N/A
|
1.51 -13% |
Olympus |
IT |
500 -20,000 ng/mL |
80 ng/mL |
N/A |
3.2 - 44% |
| (IN, immunonephelometric; IT, immunoturbidimetric; IL, immunoluminometric; ELISA, enzyme-linked immunosorbent assay) |
There are a number of advantages of the ETC analysis system over traditional methods such as the Enzyme Linked ImmunoSorbent Assay (ELISA).
Although well established, the standard ELISA method suffers from poor fluid transport; thereby, inhibiting efficient analyte movement to the planar surface of the ELISA plate. This problem is counteracted on the ETC lab-on-a-chip system by integrating microfluidic structures to actively transport reagents to the microporous bead elements.
Additionally, ELISA typically requires 2 to 3 manual washes to reduce nonspecific binding. Due to a low internal bead volume (20-30 nL) and a high flow rate (1-5mL/min), over 5000 washes can be completed per minute on the ETC lab-on-a-chip system. These washes contribute to a reduction in background signal and an enhancement of the CRP limit of detection.
Finally, the use of a porous bead allows for the creation of a long effective path length. Here the entire bead diameter may, in principle, be used for this purpose. On the other hand, a planar surface with modest roughness is typically used as the capture element for ELISA.
With more effective transport, better rinsing, and a longer pathlength, the ETC sensor system has improved limits of detection, reduced background noise, and better reproducibility.
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