Molecular fluorescence significantly enhanced by gold nanoparticles@zeolitic imidazolate framework-8

Abstract

Noble metal nanoparticles exhibit unique surface plasmon resonance dependent optical properties. On this basis, gold nanoparticles (AuNPs) encapsulated in metal-organic frameworks (MOFs) can form AuNPs@MOFs composites to modulate the optical properties of fluorescent molecules, which is less reported. In this paper, based on the fluorescence enhancement effect of AuNPs on 2-(2-Hydroxyphenyl)-1H-benzimidazole (HPBI) molecules, zeolitic imidazolate framework-8 (ZIF-8) crystals with structural stability were introduced. AuNPs@ZIF-8 exhibited a significantly pronounced fluorescence enhancement of the HPBI molecules. In addition, by comparing the fluorescence characteristics of the HPBI molecules adsorbed on AuNPs@ZIF-8 and the ones captured in AuNPs@ZIF-8, we found that the ZIF-8 can act as a spacer layer with highly effective near-field enhancement. All our preliminary results throw light on future research on the composite structures of noble metal particles and MOFs for fluorescent probes and sensing applications.