Graphene biosensors reported so far are based on polycrystalline graphene flakes which are anchored on supporting substrates. The influence of grain boundary and the scattering from substrate drastically degrade the properties of graphene and conceal the performance of intrinsic graphene as a sensor. Here we report a label-free biosensor based on suspended single crystalline graphene (SCG), which can get rid of grain boundary and substrate scattering, revealing the biosensing mechanism of intrinsic graphene for the first time. Monolayer SCG flakes were derived from low pressure chemical vapor deposition (LPCVD) method. Multiplex detection of three different lung cancer tumor markers was realized. The suspended structure can largely improve the sensitivity and detection limit (0.1. pg/ml) of the sensor, and the single crystalline nature of SCG enable the biosensor to have superior uniformity compared to polycrystalline ones. The SCG sensors exhibit superb specificity and large linear detection range from 1. pg/ml to 1. μg/ml, showing the prominent advantages of graphene as a sensing material.
Bibliographical noteFunding Information:
The work described in this paper was supported in part by the National Natural Science Foundation of China (No. 51405257 ) and Science Fund of China Post Doctor (No. 2012M520259 ). The authors acknowledge the assistance of fabrication and characterization from Minnesota Nano Center and Characterization Facility at the University of Minnesota .
- Cancer sensor
- Single crystalline
- Suspended beam