One-step synthesis of cyclodextrin-capped gold nanoparticles for ultra-sensitive and highly-integrated plasmonic biosensors.

Highlights • An eco-friendly one-step synthesis of β-CD-capped AuNPs is demonstrated. β-CD acts as both reducing and stabilizing agent. • The systematic characterization and study on the formation mechanism, size control and quality of the β-CD-capped AuNPs. • Integration of β-CD-capped AuNPs and microfiber to realize a biosensor with high-performance LSPR behavior, flexibility and small footprint. • Ultralow LOD of cholesterol of 5 aM is achieved, providing extremely low consumption of clinical samples. • Selective detection of cholesterol molecules in human serum is demonstrated, taking a step towards the practical applications. Abstract Plasmonics in conjunction with supramolecular chemistry brings new opportunities for biosensing. Modified with macrocyclic supramolecules, noble metal nanoparticles possess improved biocompatibility and highly efficient biomolecule immobilization and recognition via host-guest interaction. In this work, we synthesize high-quality and monodisperse β-cyclodextrin-capped gold nanoparticles (β-CD-capped AuNPs) in one-step facile and eco-friendly process, where β-CD functions as both reducing and capping agent. Integrated with a microfiber, the β-CD-capped AuNPs deliver promising localized surface plasmon resonance properties and ultralow detection limit of cholesterol molecules of 5 aM. The selective recognition of our proposed biosensor to cholesterol is further verified by interference study and analysis of real human serum samples. This study shows the bright prospects of supramolecular chemistry assisted plasmonics in achieving highly integrated and highly sensitive biosensing with extremely low consumption of clinical samples and small footprint. [ABSTRACT FROM AUTHOR]