Abstract
Glial fibrillary acidic protein (GFAP) is a discriminative blood biomarker for many neurological diseases, such as traumatic brain injury. Detection of GFAP in buffer solutions using biosensors has been demonstrated, but accurate quantification of GFAP in patient samples has not been reported, yet in urgent need. Herein, we demonstrate a robust on-chip graphene field-effect transistor (GFET) biosensing method for sensitive and ultrafast detection of GFAP in patient plasma. Patients with moderate–severe traumatic brain injuries, defined by the Mayo classification, are recruited to provide plasma samples. The binding of target GFAP with the specific antibodies that are conjugated on a monolayer GFET device triggers the shift of its Dirac point, and this signal change is correlated with the GFAP concentration in the patient plasma. The limit of detection (LOD) values of 20 fg/mL (400 aM) in buffer solution and 231 fg/mL (4 fM) in patient plasma have been achieved using this approach. In parallel, for the first time, we compare our results to the state-of-the-art single-molecule array (Simoa) technology and the classic enzyme-linked immunosorbent assay (ELISA) for reference. The GFET biosensor shows competitive LOD to Simoa (1.18 pg/mL) and faster sample-to-result time (<15 min), and also it is cheaper and more user-friendly. In comparison to ELISA, GFET offers advantages of total detection time, detection sensitivity, and simplicity. This GFET biosensing platform holds high promise for the point-of-care diagnosis and monitoring of traumatic brain injury in GP surgeries and patient homes.
Highlights
Glial fibrillary acidic protein (GFAP) is a discriminative blood biomarker for many neurological diseases, such as traumatic brain injury
This method was applied to the determination of GFAP in four spiked human serum samples at 0.1−0.4 ng/mL range, and the results showed good recovery
For the detection of each sample, two tests have been conducted in parallel, with the GFAP concentration ranging from 36 to 56 424 pg/mL
Summary
Glial fibrillary acidic protein (GFAP) is a discriminative blood biomarker for many neurological diseases, such as traumatic brain injury. The fluctuation of GFAP concentration accurately reflects the progress of TBI, which makes it an ideal biomarker for the TBI early diagnosis and monitoring It is a biomarker for a range of other neurological diseases,[6−10] including glioblastoma multiforme, multiple sclerosis, intracerebral hemorrhage, and Alzheimer’s disease.[11] Classic methods for the detection of GFAP include enzyme-linked immunosorbent assay (ELISA)[12] and Western blot techniques.[13] their sensitivities and detection ranges are inadequate to cover the clinically relevant concentration from a few femtomolars up to the nanomolar level.[9,14] While more advanced assays have been developed and available in some clinical laboratories, i.e., mass spectrometry[15] and single molecular array (Simoa) technology,[11] these techniques require complicated fluorescent labeling processes, demanding laser excitation, and signal capture systems, as well as highly skilled operational personnel and high maintenance cost. For clinical diagnosis and POC screening, more sensitive biosensing methods and detection data toward demonstrations in patient samples are required to measure GFAP biomarker GP surgeries and patients’ home.[6]
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