Figures & data
Figure 1 Schematic illustration of HPA axes in HIV progression. In cases of HIV, there is impaired adrenal reverse and more peripheral glucocorticoid excess.
Abbreviations: HPA, hypothalamus–pituitary–adrenal; HIV, human immunodeficiency virus; CRH, corticotropin-releasing hormone; ACTH, adrenocorticotropic hormone; AIDS, acquired immunodeficiency syndrome.
Figure 2 Schematic illustration of the stepwise fabrication and integration of electrochemical cortisol immunosensor with LTCC microfluidic manifold and M-P to detect cortisol in HIV-infected patients.
Notes: A BeagleBone microcontroller is connected with the reconfigured LMP91000EVM to perform full-range CV using three-electrode systems. The obtained data is stored in the BeagleBone SD card and transferred to the display system via SSH. Reproduced from Cruz AFD, Norena N, Kaushik A, Bhansali S. A low-cost miniaturized potentiostat for point-of-care diagnosis. Biosens Bioelectron. 2014;62:249–254.Citation16 An electrochemical immunosensor is prepared via immobilizing anti-Cab onto an SAM-modified IDE-Au electrode. Stepwise schematic illustration of LTCC-based microfluidic chip. For the making of the manifold, green taps are cut according to design and aligned to fuse them on 780°C. A fully assembled LTCC microfluidic manifold integrated with a cortisol biosensor chip.Citation18 This fabricated immunosensor is integrated with an LTCC-based microfluidic manifold for the automation of sample and reconfigured M-P for full-range CV measurement. To the reconfigured LMP9100 chip, a two-wire jumper short was removed to allow for three-electrode-based electrochemical measurements. The J_MENB jumper short was moved to the far left to enable manual configuration of the LMP91000 chip. The ADC takes the analog output from the potentiostat chip and transfers it to the microcontroller unit via SPI using the I2C interface of the LMP91000.Citation14 This developed electrochemical immunosensing method is used to detect cortisol and plasma cortisol of patients. This sensing device can be used as an analytical tool for stress-management programs for obtaining bioinformatics needed to optimize therapeutics.
Abbreviations: LTCC, low temperature co-fired ceramic; M-P, miniaturized potentiostat; HIV, human immunodeficiency virus; CV, cyclic voltammetry; anti-Cab, anticortisol antibody; SAM, self-assembled monolayer; IDE, interdigitated electrode; ADC, analog digital converter; SPI, serial peripheral interface; ADC. analog to digital converter; SAM. self-assembled monolayer; SSH. secure shell.
Table 1 Patient demographics
Figure 3 Electrochemical stepwise characterization of cortisol immunosensor and cortisol sensing calibration curve.
Notes: (A) CV response study of IDE-Au (curve a) electrode, DTSP-SAM/IDE-Au (curve b) electrode, anti-Cab/DTSP-SAM/IDE-Au immunoelectrode (curve c), EA/anti-Cab/DTSP-SAM/IDE-Au immunoelectrode (curve d), and response change after adding cortisol on sensor surface (curve e). (B) A calibration curve was obtained using an electrochemical cortisol sensor as a function of cortisol concentrations (10–500 pg/mL) on a logarithmic scale.
Abbreviations: CV, cyclic voltammetry; IDE, interdigitated electrode; DTSP, dithiobis(succinimidyl propionate); SAM, self-assembled monolayer; EA, ethanolamine; anti-Cab, anticortisol antibody; SD, standard deviation.
Table 2 Plasma cortisol detection using ELISA and electrochemical measurement
Table 3 Summary of cortisol-sensing performance using ELISA and miniaturized electrochemical cortisol sensing device
Figure 4 ELISA calibration curve to estimate plasma cortisol concentration and comparisons of plasma cortisol concentrations of HIV positive patients estimated using ELISA and CV method.
Notes: (A) Calibration plot obtained using ELISA techniques to detect plasma cortisol concentrations in HIV-positive patient. (B) A comparison of plasma cortisol of cocaine using HIV patients using ELISA and CV methods.
Abbreviations: ELISA, enzyme-linked immunosorbent assay; HIV, human immunodeficiency virus; CV, cyclic voltammetry; B%/Bo. mean absorbance of standards/means absorbance of negative control; au, arbitrary unit.
