Detection of C-reactive protein using a label-free NIR fluorescent aptasensor with a large Stokes shift based on an...

C-reactive protein (CRP), one of the classic biomarkers of inflammation, is closely related to infectious inflammation, cardiovascular disease, cancer, and other diseases. Therefore, timely and accurate detection of CRP in human blood is crucial for the discovery, diagnosis, and treatment of the aforementioned diseases. Herein, a novel label-free NIR fluorescence aptasensor with a large Stokes shift based on an AIEE anthracene derivative B and a molybdenum disulfide (MoS₂) platform was developed and used for the high sensitivity and specificity detection of CRP.

Compound B could emit near-infrared (NIR) fluorescence with a large Stokes shift (190 nm). Notably, this compound could bind with the aptamer of CRP (CRP-Apt) through electrostatic attraction to form a B/CRP-Apt complex, generating an aggregation-induced emission enhancement effect and enhancing the fluorescent intensity of B. B/CRP-Apt could be adsorbed on the surface of MoS₂ with the addition of MoS₂ to its solution, and the fluorescence of Compound B was quenched. CRP was then added to the above solution. CRP-Apt had a substantially higher affinity for CRP than MoS₂. Therefore, B/CRP-Apt detached from the surface of MoS₂ and bound to CRP, thereby restoring the fluorescence of B. Experimental results showed a good linear relationship between the fluorescent recovery intensity of B and the concentration of CRP in the concentration range of 0.3-70 ng mL^-1, with a limit of detection as low as 0.1 ng mL^-1.

The aptasensor integrates the advantages of high sensitivity of NIR fluorescence, high specificity of aptamers, good water-solubility and AIEE effect of Compound B. And it could be applied to the determination of CRP in human serum samples, while most of the reported methods can only determine CRP in spiked human serum samples.