Elevated glial fibrillary acidic protein (GFAP) in the
blood serum
is one of the promising bodily fluid markers for the diagnosis of
central nervous system (CNS) injuries, including traumatic brain injury
(TBI), stroke, and spinal cord injury (SCI). However, accurate and
point-of-care (POC) quantification of GFAP in clinical blood samples
has been challenging and yet to be clinically validated against gold-standard
assays and outcome practices. This work engineered and characterized
a novel nanoporous carbon screen-printed electrode with significantly
increased surface area and conductivity, as well as preserved stability
and anti-fouling properties. This nano-decorated electrode was immobilized
with the target GFAP antibody to create an ultrasensitive GFAP immunosensor
and quantify GFAP levels in spiked samples and the serum of CNS injury
patients. The immunosensor presented a dynamic detection range of
100 fg/mL to 10 ng/mL, a limit of detection of 86.6 fg/mL, and a sensitivity
of 20.3 Ω mL/pg mm2 for detecting GFAP in the serum.
Its clinical utility was demonstrated by the consistent and selective
quantification of GFAP comparable to the ultrasensitive single-molecule
array technology in 107 serum samples collected from TBI, stroke,
and SCI patients. Comparing the diagnostic and prognostic performance
of the immunosensor with the existing clinical paradigms confirms
the immunosensor’s accuracy as a potential complement to the
existing imaging diagnostic modalities and presents a potential for
rapid, accurate, cost-effective, and near real-time POC diagnosis
and prognosis of CNS injuries.