Abstract
Sensitive detection of vascular endothelial growth factor (VEGF165) is important for early cancer disease diagnosis in the clinic. A sensitive fluorescent sensing platform for VEGF165 detection is developed in this work. It is based on a target-triggered hybridization chain reaction (HCR) and graphene oxide (GO) selective fluorescence quenching. In this assay, in the presence of the VEGF165, the hairpin structure of Hp opens up and the initiation sequence will be exposed to Hp1 to open its hairpin structure. Then the opened Hp1 hybridizes with Hp2 to expose the complementary sequence of Hp1 which hybridizes with Hp1 again by HCR. Thus HCR would be initiated, generating super-long dsDNA. After the HCR, the double strands of the HCR product cannot be adsorbed on the GO surface. As a result, the HCR product gives a strong fluorescence signal which is dependent on the concentration of VEGF165. By using VEGF165 as a model analyte, the assay provides a highly sensitive fluorescence detection method for VEGF165 with a detection limit down to 20 pg mL−1. The proposed aptasensing strategy based on target-triggered HCR amplification can thus be realized. It was successfully applied to the determination of VEGF165 in spiked human serum, urine and saliva. Therefore, it can easily have wide applications in the diagnosis of vital diseases.
Highlights
Cancer has become one of the greatest causes of human death worldwide,[1] and so early diagnosis of cancer is important in reducing cancer mortality
The detection method was composed of three DNA probes, assistant DNA probe (Hp), hairpin probe 1 (Hp1) and hairpin probe 2 (Hp2), and VEGF165 was adopted as the target protein
The Hp1 on the 50 terminal was labeled with an FAM, and the Hp2 on the 30 terminal was labeled with an FAM
Summary
Detection of VEGF165 is important for disease diagnosis and subsequent therapy monitoring. A variety of aptamer-based analytical strategies for the detection of VEGF165 have been reported, such as differential pulse voltammetry (DPV),[20,21] electrochemical impedance spectroscopy (EIS),[11] photoelectrochemical (PEC),[22] electrochemiluminescence (ECL),[23] chemiluminescence (CL),[24,25] and time-resolved uorescence (TR-FL).[26] These methods have good speci city and stability compared to traditional approaches.[27,28] they lack a signal ampli cation strategy, resulting in low sensitivity, a narrow detection range and high error rate. One may believe that this sensing system possesses great potential for detection of proteins, biological molecules research and clinical diagnosis
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