Surfactant-mediated enhanced FRET from a quantum-dot complex for ratiometric sensing of food colorants

Abstract

The surfactant-assisted enhancement in FRET from a quantum-dot complex and its application potential in ratiometric and visual sensing of food colorants are reported herein.

Surfactant-Assisted Förster Resonance Energy Transfer from a Quantum Dot Complex for Highly Stable White Light Emission

“…The spectral overlap integral (J) can be calculated by eq 3. 28 where FD(λ) is the luminescence intensity of the donor S-QDC and ε(λ) is the extinction coefficient of RhB (λ= 485 nm). The overlap integral, J, is calculated to be 1.54429 × 10 −13 M −1 cm 3 for the current FRET pair.…”

“…The energy transfer efficiency (E) is estimated using eq 5. 28−30 The distance between the donor and acceptor (r 0 ) is calculated using…”

“…The particulars of the fabrication of ZnS QDs, QDC, and S-QDC are described in details in the Supporting Information. − The ZnS QDs display an absorption edge at 315 nm and blue luminescence centered at λ em = 445 nm, which originates owing to the surface trap states of ZnS − (Figure Ai-Ci). Figure Di clearly shows the feature peaks of (111), (220), and (311) lattice planes of cubic ZnS and thus backing the formation of ZnS QDs (Figure Di, Figure S1, Supporting Information).…”

“…These clearly demonstrate the successful synthesis of the ZnS QDs. Next, the QDC is synthesized based on the earlier reported surface complexation reaction of ZnS QDs using 8-hydroxyquinoline-5-sulfonic acid (HQS) as a complexation agent, which leads to the formation of zinc-quinolate coupled ZnS QD (termed herein as QDC). − The QDC shows cyan luminescence centered at 485 nm (which originates due to the orbital electronic transition of surface zinc-quinolate complex) − and a second absorption edge at 365 nm (which indicates the presence of a surface zinc-quinolate complex) − along with the original absorption edge of QDs (Figure Aii-Cii). No major alteration is observed in terms of the particle size distribution, lattice fringe, and the X-ray diffraction (XRD) patterns of QDs upon conversion to QDC (Figure Dii-Fii, Figure S1, Supporting Information).…”

“…The reduction in the luminescence intensity at 485 nm of S-QDC (Figure A) with increasing concentration of RhB indicates an efficient quenching mechanism, which is further evaluated using the Stern–Volmer (S–V) equation (eq ). − I 0 I = 1 + K normalS normalV [ Q ] where K SV is the Stern–Volmer constant and [Q] is the different concentrations of RhB. The Stern–Volmer constant ( K SV ) is calculated to be 3.68 × 10 4 M –1 for the current FRET pair of S-QDC and RhB (Figure C and Table ).…”