Microcentrifuge tubes as disposable immunoelectrochemical cells for the on-site detection of GFAP, biomarker of hemorrhagic stroke

Nowadays, stroke is the leading cause of mortality worldwide. Hemorrhagic (HS) and ischemic stroke (IS) have different pathophysiology and treatment. While there is a treatment for IS that reverses its most devastating effects, this does not happen with HS, and treatment for IS could even worsen HS. Therefore, differential diagnosis between IS and HS in the acute stage is an important challenge. Current diagnostic of acute stroke relies on neuroimaging techniques that provide valuable information but not always are readily available. Therefore, the development of analytical tools for rapid and on-site detection of biomarkers capable of differentiate between the types of stroke could enhance the optimally manage of patients. Glial fibrillary acidic protein (GFAP) is considered one of the acute HS biomarkers; its levels in serum are increased in patients with HS in comparison with IS patients.

In this work, a sandwich-type immunoassay for the determination of GFAP was wholly performed inside a microcentrifuge tube immobilizing the capture antibody on its bottom. The electrodes needed for the detection are included in the cap in a simple and innovative strategy that allows to follow an all-in-one procedure. Thus, the cap is drilled with three stainless-steel pins that act as electrodes. With this design, when the tube is closed the head of the pins is inside and thus, once the immunoassay is finished, the tube is turned upside down allowing the electrochemical detection in the same tube.

The good precision of this tube-based electrochemical cell makes possible to obtain a point-of-need device with huge potential for analytical applications that require rapid and on-site response. In the case of GFAP determination, this device, combined with a handheld potentiostat, would be of great interest for its use in out-of-hospital sites to help determine the cause of the stroke in the acute stage.