An aptamer-based shear horizontal surface acoustic wave biosensor with a CVD-grown single-layered graphene film for high-sensitivity detection of a label-free endotoxin

Abstract

The thickness of the sensitive layer has an important influence on the sensitivity of a shear horizontal surface acoustic wave (SH-SAW) biosensor with a delay-line structure and lower layer numbers of graphene produce better sensitivity for biological detection. Therefore, a label-free and highly sensitive SH-SAW biosensor with chemical vapor deposition (CVD-)-grown single-layered graphene (SLG) for endotoxin detection was developed in this study. With this methodology, SH-SAW biosensors were fabricated on a 36°Y-90°X quartz substrate with a base frequency of 246.2 MHz, and an effective detection cell was fabricated using acrylic material. To increase the surface hydrophilicity, chitosan was applied to the surface of the SLG film. Additionally, the aptamer was immobilized on the surface of the SLG film by cross-linking with glutaraldehyde. Finally, the sensitivity was verified by endotoxin detection with a linear detection ranging from 0 to 100 ng/mL, and the detection limit (LOD) was as low as 3.53 ng/mL. In addition, the stability of this type of SH-SAW biosensor from the air phase to the liquid phase proved to be excellent and the specificity was tested and verified by detecting the endotoxin obtained from Escherichia coli (E. coli), the endotoxin obtained from Pseudomonas aeruginosa (P. aeruginosa), and aflatoxin. Therefore, this type of SH-SAW biosensor with a CVD-grown SLG film may offer a promising approach to endotoxin detection, and it may have great potential in clinical applications.

Current Trends on Surface Acoustic Wave Biosensors

“…Ji et al. had engineered a high sensitivity SH‐SAW biosensing device coated with a single‐layered graphene film to detect endotoxin, [ 198 ] and the outline of their device was as shown in Figure . Their biosensor was fabricated by lithography technique with a quartz piezoelectric substrate that had a basic frequency of 246.2 MHz.…”

“…Reproduced with permission. [ 198 ] Copyright 2020, Springer Nature.…”

Recent Advances in Nanomaterial-Based Aptasensors in Medical Diagnosis and Therapy

“…The detection of biomarkers could be in vitro as well as in vivo since graphene can act as a delivery vehicle for aptamers into living cells or animals [ 1 ]. An in vitro detection of endotoxin, a complex lipopolysaccharides found in cell walls of Gram-negative bacteria, was performed using a highly sensitive and label-free shear horizontal surface acoustic wave (SH-SAW)/single-layer graphene (SLG)-based aptasensor [ 46 ]. The SH-SAW/SLG aptasensor demonstrated a linear relationship with the endotoxin concentration range from 0 to 100 ng/mL and reached a detection limit of 3.53 ng/mL.…”

Biosensors Based on Mechanical and Electrical Detection Techniques

“…However more recently, with the more widespread understanding and availability of graphene, this is starting to be used as a detection surface. An example of this comes from the work of Ji et al producing a SAW biosensor for the detection of bacterial endotoxin with a high sensitivity of 3.5 ug L −1 [ 126 ]. An alternative is the design developed by Lamanna et al using a thin molybdenum layer on AlN instead of gold on quartz [ 114 , 127 ].…”