An aptasensor for carcinoembryonic antigen based on upconversion fluorescence resonance energy transfer

• A new aptasensor for CEA detection is constructed based on upconversion fluorescence resonance energy transfer.
• The near-infrared excitation and anti-Stokes emission of upconversion phosphors facilitate a homogeneous assay procedure with the ability to overcome background interference.
• The π–π stacking interaction between CEA aptamer and carbon nanoparticles enables the assembly of donor and acceptor.
• The sensor exhibits high sensitivity and specificity.
• Excellent performances are obtained both in aqueous buffer and human serum samples, suggesting potential applications in clinical analysis.

In this work, an aptasensor for carcinoembryonic antigen (CEA) determination was constructed on the basis of fluorescence resonance energy transfer (FRET) between upconversion phosphors (UCPs) and carbon nanoparticles (CNPs). Polyacrylic acid (PAA)-capped UCPs (NaYF4:Yb, Er) were employed as the energy donor, which were covalently tagged with an amino group modified CEA aptamer (5′-NH2-(A)5 ATA CCA GCT TAT TCA ATT-3′). The fluorescence of UCPs was dramatically quenched by CNPs due to the π–π stacking interaction between CEA aptamer and CNPs, which brought UCPs and CNPs in close proximity and triggered the energy transfer from UCPs to CNPs. When the CEA protein was introduced into the UCPs–aptamer–CNPs complex, the CEA aptamer preferentially interacted with CEA protein, leading to a structural change of the aptamer which was unfavorable for the π–π stacking. As a result, the energy transfer process was blocked and the fluorescence of UCPs was recovered. The degree of fluorescence restoration linearly depended on CEA concentration in the range of 0.1–40 ng/mL in both buffer solution and human serum samples. The aptasensor exhibited high specificity toward CEA protein without being interfered by other biomolecules. The proposed method showed the potential of clinical applications because of the good sensing performance and ease of operation.

With the use of upconversion phosphors as the energy donor and carbon nanoparticles as the energy acceptor, a new detection method for carcinoembryonic antigen based on upconversion fluorescence resonance energy transfer was developed. The sensor presented high sensitivity and specificity, and it also showed the ability to overcome background interference in serum samples.Figure optionsDownload as PowerPoint slide