A ratiometric fluorescence sensor for caffeine

Abstract

The dye disodium 3,4:3',4'-bibenzo[b]thiophene-2,2'-disulfonate can be used as a molecular probe for the fluorimetric detection of caffeine in aqueous solution. The fluorescence response is attributed to non-covalent interactions of caffeine with the dye in the ground state and in the excited state. The bimodal interaction allows performing ratiometric measurements with very good selectivity over structurally related analytes. The dye was also used to develop a simple test strip for the visual differentiation of normal and decaffeinated coffee with a standard UV lamp.

A fast charge‐Dependent atom‐pairwise dispersion correction for DFTB3

“…As illustrated by the examples provided in Figure , the latest 3OB parameterization by Cui et al offers a dramatic improvement over MIO11 for the dispersion corrected gas phase geometries. DFTB/3OB‐dDMC leads to four geometries that are in close agreement with the reference PBE0‐dDsC/def2‐SVP or RI‐MP2/TZ data. In particular, the T‐shape thiophene dimer and the illustrative caffeine–receptor complex are well reproduced with both DFTB/3OB‐dDMC and DFTB/3OB‐D3 (root mean square deviation (RMSD) < 0.4 Å).…”

“…DFTB/3OB‐dDMC leads to four geometries that are in close agreement with the reference PBE0‐dDsC/def2‐SVP or RI‐MP2/TZ data. In particular, the T‐shape thiophene dimer and the illustrative caffeine–receptor complex are well reproduced with both DFTB/3OB‐dDMC and DFTB/3OB‐D3 (root mean square deviation (RMSD) < 0.4 Å). The ‐D3 description of the annulated β‐trithiophene dimer converges toward another minima (RMSD= 2.025 Å), whereas dDMC remains in agreement with the reference data (RMSD = 0.6 Å).…”

“…The simulations on the caffeine–receptor complex are conducted in the canonical (NVT) ensemble using the Langevin thermostat with a 2 ps −1 friction. We found that a 1 fs time step is small enough to avoid energy drifts.…”

Make Caffeine Visible: a Fluorescent Caffeine “Traffic Light” Detector

“…Two aqueous sensors were reported by Severin group, both of which utilize π-stacking as the driving force for binding caffeine2930. CO, on the other hand, interacts with caffeine not only through π-stacking, but also through hydrogen bonding and electrostatic interactions, as exhibited by FT-IR and NMR.…”

“…The authors tested this sensor in different samples by extraction method, yet the incorporation of toxic organic solvent (chloroform) and the fluorescence turn-off feature renders difficulties in real-life application. Although they further developed a similar-structure ratiometric caffeine fluorescence sensor and incorporated it into a caffeine detection strip30, it would still require more than 20 minutes for caffeine detection in beverages. Moreover, the relatively low fluorescence response adds difficulties to direct caffeine observation.…”