Ultrasensitive detection of adrenocorticotropin hormone (ACTH) using disposable phenylboronic-modified electrochemical immunosensors

Abstract

This work reports for the first time an electrochemical immunosensor for the determination of adrenocorticotropin hormone (ACTH). The immunoelectrode design involves the use of amino phenylboronic acid for the oriented immobilization of anti-ACTH antibodies onto screen-printed carbon modified electrode surfaces. A competitive immunoassay between the antigen and the biotinylated hormone for the binding sites of the immobilized antibody was performed. The electroanalytical response was generated by using alkaline phosphatase-labelled streptavidin and 1-naphtyl phosphate as the enzyme substrate. The electrochemical oxidation of the enzyme reaction product, 1-naphtol, measured by differential pulse voltammetry was employed to monitor the affinity reaction. Under the optimized working conditions, an extremely low detection limit of 18 pg/L was obtained. Cross-reactivity was evaluated against other hormones (cortisol, estradiol, testosterone, progesterone, hGH and prolactin) and the obtained results demonstrated an excellent selectivity. The developed immunosensor was applied to a human serum sample containing a certified amount of ACTH with good results.

Multiplexed Ultrasensitive Determination of Adrenocorticotropin and Cortisol Hormones at a Dual Electrochemical Immunosensor

“…These methodologies allowed ranges between a few units up to various hundreds of ng/L ACTH to be covered [19][20][21], concentrations that are much larger than those appearing in the linear range obtained for this hormone with the developed Strept-AP/ Biotin-ACTH/anti-ACTH/APBA/SPCE1 immunosensor. On the other hand, the electrochemical immunosensor for ACTH previously described by our group provided a detection limit of 18 pg/L [15]. This slight difference is most likely due to the remarkably smaller surface area of the SPCE working electrodes in the dual device (5.6 mm 2 ) with respect to that of the single SPCE used for the individual determination of ACTH (12.56 mm 2 ).…”

“…In a first approach, the experimental conditions optimized previously for ACTH (2 % BSA and 1h incubation time) [15] were used. Although the unspecific responses from Strept-AP at SPCE were found to be always lower than 10 % of the signals obtained with the Strept-AP/Biotin-ACTH/anti-ACTH/ APBA/SPCE, the nonspecific binding was remarkably higher when cortisol-AP was involved.…”

“…Magnetic electrochemical immunosensors were also developed for testosterone [12], prolactin [13] and cortisol [14]. Moreover, the ultrasensitive detection of ACTH was accomplished by using disposable phenylboronic-modified electrochemical immunosensors [15].…”

Disposable Biosensors for Clinical Diagnosis

“…4), 42 73 testosterone, 74 human growth hormone (hGH), 75 adrenocorticotropin, 76 prolactin, 41 and estradiol. 12 Regarding the field of cardiology, immunosensor devices have been employed for predicting the risk of fatal cardiovascular diseases by sensing the nonspecific biomarker C-reactive protein.…”

Aptamer-antibody sandwich assay for cytochrome c employing an MWCNT platform and electrochemical impedance

“…This technique is very sensitive to changes in the interfacial properties of the modified electrodes caused by biorecognition events at the electrode surface [22,23]. For this reason, EIS is becoming an attractive electrochemical technique for numerous applications such as immunosensing [24], enzyme activity determination [25], genosensing [26,27], studies of corrosion [28] and other surface phenomena [29].…”