Detection of disease biomarkers from whole blood is very important in disease prevention and management. However, new generation assays like point-of-care or mobile diagnostics face a myriad of challenges in detecting proteins from whole blood. In this research, we have designed, fabricated, and characterized a portable biomedical sensor for the detection of cardiac troponin I (cTnI) directly from whole blood, without sample pretreatments. The sensing methodology is based on an extended gate electrical double layer (EDL) gated field effect transistor (FET) biosensor that can offer very high sensitivity, a wide dynamic range, and high selectivity to target analyte. The sensing methodology is not impeded by electrostatic screening and can be applied to all types of FET sensors. A portable biomedical system is designed to carry out the diagnostic assay in a very simple and rapid manner, that allows the user to screen for target protein from a single drop of blood, in 5 min. This biomedical sensor can be used in hospitals and homes alike, for early detection of cTnI which is a clinical marker for acute myocardial infarction. This sensing methodology could potentially revolutionize the modern health care industry.
We
have developed a swift and simplistic protein immunoassay using
aptamer functionalized AlGaN/GaN high electron mobility transistors
(HEMTs). The unique design of the sensor facilitates protein detection
in a physiological salt environment overcoming charge screening effects,
without requiring sample preprocessing. This study reports a tunable
and amplified sensitivity of solution-gated electric double layer
(EDL) HEMT-based biosensors, which demonstrates significantly enhanced
sensitivity by designing a smaller gap between the gate electrode
and the detection, and by operating at higher gate voltage. Sensitivity
is calculated by quantifying NT-proBNP, a clinical biomarker of heart
failure, in buffer and untreated human serum samples. The biosensor
depicts elevated sensitivity and high selectivity. Furthermore, detailed
investigation of the amplified sensitivity in an increased ionic strength
environment is conducted, and it is revealed that a high sensitivity
of 80.54 mV/decade protein concentration can be achieved, which is
much higher than that of previously reported FET biosensors. This
sensor technology demonstrates immense potential in developing surface
affinity sensors for clinical diagnostics.
In this research, we have developed a rapid diagnostic assay using a high-electron-mobility transistor (HEMT)-based biosensor to screen for fibrinogen in clinical plasma samples. High sensitivity over a wide detection range (0-5 g/L), good selectivity, low-cost fabrication, portability, and simplicity of use are key features of our biosensor. Early diagnosis of heart disease in low-, medium-, and high-risk patients is possible with an assay turnaround time of 5 min and a plasma sample volume of 5-10 µL. High sensitivity and low detection limits (0.5 g/L) are made possible in environments with high salt concentrations because the HEMT sensor design overcomes the charge screening effect associated with a very small Debye length. This biosensor technology demonstrates the potential for development as a point-of-care or homecare diagnostic device for quick and easy assessment of cardiovascular disease (CVD) risk.
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