Biomedical Engineering Reference
In-Depth Information
21.4
Future Commercially Available Immunosensors
Progress is being made in MESOSYSTEM Inc. for developing different types of sensors
[94,131,132]. Micro fluidics cartridge and system has been shown in Figure 21.7.
A group has previously reported a sandwich-based strip immunoassay for rapid detection
of
E. coli
O157:H7 [133]. In the present study, a microcapillary flow injection liposome
immunoanalysis (mFILIA) system was developed for the detection of heat-killed
E. coli
O157:H7. A fused-silica microcapillary with anti-
E. coli
O157:H7 antibodies chemically immo-
bilized on the internal surface via protein A served as an immunoreactor or immunosepara-
tor for the mFILIA system. Liposomes tagged with anti-
E. coli
O157:H7 and encapsulating a
fluorescent dye were used as the detectable label. In the presence of
E. coli
O157:H7, sandwich
complexes were formed between the immobilized antibodies in the column, the sample of
E. coli
O157:H7 and the antibody-tagged sulforhodamine-dye-loaded liposomes. Signals gen-
erated by lysing the bound liposomes with 30-mM
n
-octyl-
-D-glucopyranoside were meas-
ured by a fluorometer. The detected signal was directly proportional to the amount of
E. coli
O157:H7 in the test sample. The mFILIA system successfully detected as low as 360 cells/mL
(equivalent of 53 heat-killed bacteria in the 150
L of the sample solution injected). MeOH
(30%) was used for the regeneration of antibody-binding sites in the capillary after each meas-
urement, which allowed the immunoreactor or immunoseparator to be used for at least 50
repeated assays. The calibration curve for heat-killed
E. coli
O157:H7 has a working range of
6
10
7
cells, and the total assay time was less than 45 min. A coefficient of varia-
tion for triplicate measurements was
10
3
to 6
8.9%, which indicates an acceptable level of repro-
ducibility for this newly developed method [134-136].
BioMonitor Product Concept
MesoRAC
TM
Aerosol collector
9V Battery
Circuit Board
with optics
Alarm
indicators
Cartridge with
reagents
•
Biosensor technology
•
Electrochemical assay
•
University of New Mexico
•
Microfluidic cartridge
technology
•
U. Washington
•
Micronics, Inc.
Support from
•
DARPA (Microflumes)
•
•
SBCOM (MesoSystems
SBIR)
Micronics, Inc. cartridge
Redmond, WA
FIGURE 21.7
Micro fluidics cartridge and system.
