Polydopamine-based molecular imprinted optic microfiber sensor enhanced by template-mediated molecular rearrangement for ultra-sensitive C-reactive protein detection

Conventional molecular imprinting technique is utilized for the construction of three dimensional binding cavities just providing complementary shape and size of the specific template molecule for the recognition of the same. Although molecular imprinting is able to largely improve the selectivity of detection, it lowers the limit of detection (LOD) a little. In this study, a microfiber interference sensor decorated with the polydopamine (PDA)-based molecularly imprinted with C-reactive protein (CMIP-PDA) was developed for C-reactive protein (CRP) detection, in which template molecule induced dopamine2/5,6-dihydroxyindole (DHI) trimer rearrangement in the dopamine self-polymerization process and further forms complementary hydrophobic/hydrophilic and charge distribution other than shape and size in the imprinting cavity corresponding to template. The combination of optical fiber interferometer with enhancement effect from template-mediated rearrangement remarkably boosts the recognition sensitivity. Therefore, our sensor sensitivity reaches 0.881 nm/ (lg ng/mL) and the LOD is found to be 5.813 × 10−10 ng/mL, which is about 8 orders of magnitude lower than the commercial sandwich-type ELISA kit. Moreover, the CMIP-PDA microfiber sensor has excellent repeatability and high selectivity for the target molecule. These findings confirm that the proposed PDA-based molecular imprinting can provide an ultrasensitive, rapid, low cost and label-free CRP diagnosis as well as can be varied to meet any specific biomarkers. This work also opens up new opportunity to quantitatively monitor biological molecules with extremely low concentration.