42
M. A. Espinosa-Hernandez et al.
Fig. 2.4 a Device with the test strip being removed from storage compartment, b Obtaining sweat
and saliva samples, c inserting test strip into optical system for reading, d pH analysis with test strip
inserted Oncescu et al. (2013)
loads the calibration data and user interface, the test strip was to be inserted into the
case and touch “Analyze” on the screen. The app takes a flashed image of the strip
and then is categorized by color.
Matˇ ejovský and Pitschmann have created an addition from glass nanofibers to the
Detehit biosensor (Pitschmann et al. 2018) for cholinesterase inhibitors (Matˇ ejovský
and Pitschmann 2018). These inhibitors interfere with the nerve impulses cholinergic transfer mechanism. The biosensor was made based on the cholinesterase
reaction based on enzymatic degradation of the substrate to obtain the appropriate
acid or thiocholine. The Detehit biosensor was a detection ribbon based on hardened PVC and contains a detection fabric with immobilized and stabilized acetylcholinesterase (AChE), and a cellulose paper strip with acetylthiocholine iodide
(ATChI) and Ellman’s reagent, shown in Fig. 2.5. For its operation, the detection
fabric ought to be moist and exposed to air, by placing the fabric in contaminated
water or pressing a wet detection zone against the test surface. The cellulose strip
was squeezed with the exposed detection fabric, making the color change visible to
be analyzed. If the white detection fabric changed to yellow, there were no inhibitors,
however, if the color did not change, there were inhibitors present. This is depicted
in Fig. 2.6a. However, because the color differentiation was sometimes difficult, a
new substrate carrier made of glass nanofibers and using a chromogenic reagent
(Ellman’s reagent) was developed to increase the intensity of the yellow color. The
two were compared by having Ellman’s reagent combined with the ATChI and an
alternate butyrylthiocholine iodide (BuTChI) and testing the new device with AChE
and butyrylcholinesterase (BuChE). It was a 10 cm long by 1 cm wide plastic strip,
having an indication fabric on one end with an immobilized enzyme covering about 1
cm
2 , while the carrier was at the other end impregnated with a substrate and an indicator, also measuring 1 cm
2 , as seen in Fig. 2.6b. The detection fabric was made by
impregnating a white cellulose fabric with a solution containing the enzyme (AChE
tissue, AChE, or BuChE) with total activity of 21 nkat/mL, 5% of dextran, and 2%
M. A. Espinosa-Hernandez et al.
Fig. 2.4 a Device with the test strip being removed from storage compartment, b Obtaining sweat
and saliva samples, c inserting test strip into optical system for reading, d pH analysis with test strip
inserted Oncescu et al. (2013)
loads the calibration data and user interface, the test strip was to be inserted into the
case and touch “Analyze” on the screen. The app takes a flashed image of the strip
and then is categorized by color.
Matˇ ejovský and Pitschmann have created an addition from glass nanofibers to the
Detehit biosensor (Pitschmann et al. 2018) for cholinesterase inhibitors (Matˇ ejovský
and Pitschmann 2018). These inhibitors interfere with the nerve impulses cholinergic transfer mechanism. The biosensor was made based on the cholinesterase
reaction based on enzymatic degradation of the substrate to obtain the appropriate
acid or thiocholine. The Detehit biosensor was a detection ribbon based on hardened PVC and contains a detection fabric with immobilized and stabilized acetylcholinesterase (AChE), and a cellulose paper strip with acetylthiocholine iodide
(ATChI) and Ellman’s reagent, shown in Fig. 2.5. For its operation, the detection
fabric ought to be moist and exposed to air, by placing the fabric in contaminated
water or pressing a wet detection zone against the test surface. The cellulose strip
was squeezed with the exposed detection fabric, making the color change visible to
be analyzed. If the white detection fabric changed to yellow, there were no inhibitors,
however, if the color did not change, there were inhibitors present. This is depicted
in Fig. 2.6a. However, because the color differentiation was sometimes difficult, a
new substrate carrier made of glass nanofibers and using a chromogenic reagent
(Ellman’s reagent) was developed to increase the intensity of the yellow color. The
two were compared by having Ellman’s reagent combined with the ATChI and an
alternate butyrylthiocholine iodide (BuTChI) and testing the new device with AChE
and butyrylcholinesterase (BuChE). It was a 10 cm long by 1 cm wide plastic strip,
having an indication fabric on one end with an immobilized enzyme covering about 1
cm
2 , while the carrier was at the other end impregnated with a substrate and an indicator, also measuring 1 cm
2 , as seen in Fig. 2.6b. The detection fabric was made by
impregnating a white cellulose fabric with a solution containing the enzyme (AChE
tissue, AChE, or BuChE) with total activity of 21 nkat/mL, 5% of dextran, and 2%