Label-free aptasensor based on ultrathin-linker-mediated hot-spot assembly to induce strong directional fluorescence.
We have demonstrated the proof-of-concept of a label-free biosensor based on emission induced by an extreme hot-spot plasmonic assembly. In this work, an ultrathin linking layer composed of cationic polymers and aptamers was fabricated to mediate the assembly of a silver nanoparticles (AgNPs)-dyes-gold film with a strongly coupled architecture through sensing a target protein. Generation of directional surface plasmon coupled emission (SPCE) was thus stimulated as a means of reporting biorecognition. Both the biomolecules and the nanoparticles were totally free of labeling, thereby ensuring the activity of biomolecules and allowing the use of freshly prepared metallic nanoparticles with large dimensions. This sensor smartly prevents the plasmonic assembly in the absence of targets, thus maintaining no signal through quenching fluorophores loaded onto a gold film. In the presence of targets, the ultrathin layer is activated to link NPs-film junctions. The small gap of the junction (no greater than 2 nm) and the large diameter of the nanoparticles (~100 nm) ensure that ultrastrong coupling is achieved to generate intense SPCE. A >500-fold enhancement of the signal was observed in the biosensing. This strategy provides a simple, reliable, and effective way to apply plasmonic nanostructures in the development of biosensing.
Department of Chemistry and the MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
Shuo-Hui
SH
Cao
Wei-Peng
WP
Cai
Qian
Q
Liu
Kai-Xin
KX
Xie
Yu-Hua
YH
Weng
Si-Xin
SX
Huo
Zhong-Qun
ZQ
Tian
Yao-Qun
YQ
Li
D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001483:Base Sequence; D004867:Equipment Design; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*; D013917:Thrombin / Q000032:analysis*
D052157:Aptamers, Nucleotide; D005456:Fluorescent Dyes; D011108:Polymers; C081676:thrombin aptamer; D012834:Silver; D006046:Gold; D013917:Thrombin