Fluorescence resonance energy transfer from pyrene nanoparticles to riboflavin: Spectroscopic insights and analytical application

Abstract

The aqueous suspension of fluorescent pyrene nanoparticles (PyNPs) were prepared by a reprecipitation method in the presence of sodium dodecyl sulphate (SDS) as a stabilizer. The PyNPs shows bathochromically shifted aggregation induced enhanced emission (AIEE) in the spectral region 400 nm to 600 nm peaking at 466 nm where Riboflavin (RF) absorbs strongly. The systematic FRET experiments performed by measuring fluorescence quenching of PyNPs with successive addition of RF analyte exploited the use of PyNPs as nano probe for detection of RF in aqueous solution with lower limit of detection 10.163 × 10^-5 mol.L^-1. The fluorescence of PyNPs was quenched by RF and quenching is in accordance with the Stern-Volmer relation. The distance r between the donor (PyNPs) and acceptor (RF) molecules was obtained according to the fluorescence resonance energy transfer. The evaluation of photo kinetic and thermodynamic parameters such as quenching rate constant (k_q), enthalpy change (ΔH), Gibbs free energy change (ΔG) and entropy change (ΔS) was calculated by quenching results obtained at different constant temperatures. The proposed FRET method based on fluorescence quenching of PyNPs was used further to develop an analytical relation for estimation of RF from pharmaceutical samples available commercially in the market.