A multimode aptasensor based on hollow gold nanoparticles and structure switching of aptamer: Fast and sensitive detection of carcinoembryonic antigen

Abstract

A fast and sensitive carcinoembryonic antigen (CEA) aptasensor with multiple detection modes was developed. It is based on hollow gold nanoparticles (HGNPs) and horse radish peroxidase (HRP) as both labels and signal amplification elements. In fabrication, capture DNA (cpDNA) was modified on magnetic beads, and reporter DNA (rpDNA) and HRP were co-modified on HGNPs. A combination DNA, containing a DNA aptamer (GAC-P) segment, hybridized with cpDNA and rpDNA, forming a satellite-structured biosensor. In response to CEA, the aptamer switches its structure, releasing rpDNA/HGNPs/HRP under magnetic separation. The surface plasmon resonance of HGNPs and the HRP enzyme activity of the supernatant were observed/detected with naked eyes, UV–vis spectroscopy, and electrochemistry techniques. The assay time is as short as ~45 min. CEA levels can be differentiated with naked eyes. The absorbance at 677 nm is linearly proportional to CEA concentration from 10 to 250 ng mL−1, with a limit of detection (LOD) of 8.6 ng mL−1. In contrast, the differential pulse voltammetry (DPV) peak current at -0.057 V is linearly correlated with CEA concentration in the range of 2−250 ng mL−1, with an LOD of 0.78 ng mL−1. The LOD values are lower than cancer patient threshold levels. The aptasensor exhibits negligible responses to interfering proteins. In addition, it displays good reproducibility, stability, accuracy and easiness of usage. The recovery rate for CEA spiked human serum samples are 100±5%. The developed assay strategy should provide a general platform for detecting other interested biomarkers.

Keywords

• Hollow gold nanoparticles
• Tumor marker
• DNA aptamer
• Structure switching
• Signal amplification
• Carcinoembryonic antigen detection