A polydopamine nanospheres modified fiber optic SPR biosensor for specific detection of C-reactive protein.

• The prepared biosensor has the advantages of good bio-sensing performance, short measurement time and low limit of detection. • The RI sensitivity can reach 2427.68 nm/RIU, showing a superior performance compared to the raw sensors coated by Au film. • The sensor was used to detect the concentration of CRP, with the bio-sensitivity of 0.09 nm/(µg/mL) and LOD of 0.22 µg/mL. C-reactive protein (CRP) is a vital inflammatory marker in humans and a key single marker of cardiovascular diseases. In this paper, the concentration of CRP was specifically detected by a polydopamine nanospheres (PDA-NPs) developed surface plasmon resonance (SPR) sensor with high accuracy. PDA-NPs is a self-polymerizing material that can be obtained from dopamine through the mussel adhesion effect. The PDA-NPs (diameter ≈ 100 nm) modified SPR sensor exhibits enhanced refractive index (RI) sensitivity and bio-sensitivity attributed to the large specific surface area and high surface reactivity of the PDA-NPs. The developed sensor demonstrates a RI sensitivity of 2427.68 nm/RIU, presenting a 55.7% increase compared to the raw sensor (RI sensitivity was 1559.08 nm/RIU). Moreover, the developed biosensor is used to detect CRP specifically. The bio-sensitivity reaches 0.09 nm/(µg/mL), while the limit of detection (LOD) reaches 0.22 µg/mL. These findings indicate that the developed biosensor can specifically detect CRP with a low LOD. Therefore, this PDA-NPs modified biosensor has great potential in clinical detection and other bio-detection filed. [ABSTRACT FROM AUTHOR]