A PDA/AuNPs/PDANPs sandwich structure modified optical fiber surface plasmon resonance (SPR) biosensor for specific detecting of rabbit IgG were proposed in this paper. On the proposed sensor, polydopamine (PDA), gold nanoparticles (AuNPs) and polydopamine nanoparticles (PDANPs) were sequentially deposited to form a multilayer hybrid structure. The refractive index (RI) sensitivity of the sensor has been significantly enhanced through the strong coupling effects of SPR and localized surface plasmon resonance. The sensor achieves an RI sensitivity of3009.58 nm/RIU, representing a 3-fold increase compared to the original SPR sensor. In addition, due to the high surface activity and large specific surface area of PDANPs, the biosensitivity of the sensor has been enhanced. The sensor demonstrated specific detection of Rabbit IgG with a biosensitivity of 0.9157 nm/(μg/mL) and limit of detection (LOD) of 22 ng/mL. These findings indicate that the prepared sensor can specifically detect Rabbit IgG with high precision and a low LOD. Therefore, this PDA/AuNPs/PDANPs sandwich structure modified biosensor has great potential in clinical detection and other bio-detection fields.
Huanhuan Li,Qiyi Bei,Wenhao Zhang,Murugavelu Marimuthu,Md. Mehedi Hassan,Suleiman A. Haruna,Quansheng Chen
Mercury (Hg 2+ ) is a potentially toxic heavy metal ion found to be drastically deleterious to humans. Herein, an ultrasensitive fluorescence sensor was developed using three-dimensional upconversion nanoclusters (EBSUCNPs) and aptamer-modulated thymine-Hg 2+ -thymine strategy. The EBSUCNPs were used as the energy donors, the PDANPs served as the acceptors, and the aptamer was applied as an identification tag for Hg 2+ . Due to the energy transfer effect, the fluorescence of EBSUCNPs can be effectively quenched by Polydopamine nanoparticles (PDANPs). In the existence of Hg 2+ , T (thymine)-rich aptamers between EBSUCNPs and PDANPs were hybridized with Hg 2+ to yield thymine-Hg 2+ -thymine and folded back to hairpin structure, causing PDANPs to detach from the EBSUCNPS and the recovery of fluorescence. Under optimum conditions, the linear sensing range of Hg 2+ was 0.5–20 µg/L, and the detection limit was 0.28 µg/L. Furthermore, it exhibited excellent selectivity and anti-interference, which made it an ideal method for identifying Hg 2+ in spiked samples.
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