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Flexible nanoporous tunable electrical double layer biosensors for sweat diagnostics.

Munje RD, Muthukumar S, Panneer Selvam A, Prasad S - Sci Rep (2015)

Bottom Line: High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors.Specificity in synthetic sweat was demonstrated using a cytokine IL-1β.Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, EC 39, Richardson, TX 75080.

ABSTRACT
An ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

No MeSH data available.


Structural characteristics of sensor.(a) SEM image of nanoporous polyamide substrate. (b) SEM image of bio-functionalized area of ZnO in sensor on nanoporous polyamide substrate. (c) Schematic of the biosensor configuration (d) actual sensor image.
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f1: Structural characteristics of sensor.(a) SEM image of nanoporous polyamide substrate. (b) SEM image of bio-functionalized area of ZnO in sensor on nanoporous polyamide substrate. (c) Schematic of the biosensor configuration (d) actual sensor image.

Mentions: We used Pulsed Laser Deposition (PLD) technique to deposit ZnO thin films in the active regions. PLD deposited thin films highly crystalline and uniform with stable electrical properties even after deposition on flexible substrates19. PLD deposited ZnO has also been used for glucose and cortisol detection, using enzyme based assays2021. Figure 1 show ZnO deposited on nanoporous polyamide substrate and the schematic of the sensor device. Parylene is deposited and patterned on the nanoporous polyamide substrate to isolates the entire sensor surface except the ZnO channel area from the liquid. Parylene fabrication is followed by transverse electrode fabrication. ZnO is deposited and patterned on the nanoporous polyamide substrate within the area enclosed by Parylene so that there is small overlap with the transverse electrodes. The orthogonal, third electrode is then fabricated above ZnO region. Electrical isolation of the electrodes is verified post sensor fabrication to ensure functionality prior to biosensor characterization.


Flexible nanoporous tunable electrical double layer biosensors for sweat diagnostics.

Munje RD, Muthukumar S, Panneer Selvam A, Prasad S - Sci Rep (2015)

Structural characteristics of sensor.(a) SEM image of nanoporous polyamide substrate. (b) SEM image of bio-functionalized area of ZnO in sensor on nanoporous polyamide substrate. (c) Schematic of the biosensor configuration (d) actual sensor image.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588585&req=5

f1: Structural characteristics of sensor.(a) SEM image of nanoporous polyamide substrate. (b) SEM image of bio-functionalized area of ZnO in sensor on nanoporous polyamide substrate. (c) Schematic of the biosensor configuration (d) actual sensor image.
Mentions: We used Pulsed Laser Deposition (PLD) technique to deposit ZnO thin films in the active regions. PLD deposited thin films highly crystalline and uniform with stable electrical properties even after deposition on flexible substrates19. PLD deposited ZnO has also been used for glucose and cortisol detection, using enzyme based assays2021. Figure 1 show ZnO deposited on nanoporous polyamide substrate and the schematic of the sensor device. Parylene is deposited and patterned on the nanoporous polyamide substrate to isolates the entire sensor surface except the ZnO channel area from the liquid. Parylene fabrication is followed by transverse electrode fabrication. ZnO is deposited and patterned on the nanoporous polyamide substrate within the area enclosed by Parylene so that there is small overlap with the transverse electrodes. The orthogonal, third electrode is then fabricated above ZnO region. Electrical isolation of the electrodes is verified post sensor fabrication to ensure functionality prior to biosensor characterization.

Bottom Line: High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors.Specificity in synthetic sweat was demonstrated using a cytokine IL-1β.Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, EC 39, Richardson, TX 75080.

ABSTRACT
An ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

No MeSH data available.