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

Abstract

Caffeine has attracted abundant attention due to its extensive existence in beverages and medicines. However, to detect it sensitively and conveniently remains a challenge, especially in resource-limited regions. Here we report a novel aqueous phase fluorescent caffeine sensor named Caffeine Orange which exhibits 250-fold fluorescence enhancement upon caffeine activation and high selectivity. Nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy indicate that π-stacking and hydrogen-bonding contribute to their interactions while dynamic light scattering and transmission electron microscopy experiments demonstrate the change of Caffeine Orange ambient environment induces its fluorescence emission. To utilize this probe in real life, we developed a non-toxic caffeine detection kit and tested it for caffeine quantification in various beverages. Naked-eye sensing of various caffeine concentrations was possible based on color changes upon irradiation with a laser pointer. Lastly, we performed the whole system on a microfluidic device to make caffeine detection quick, sensitive and automated.

A new approach for turn-on fluorescence sensing of l-DOPA

“…S10 and S11, ESI †). 33 By comparing the actual L-DOPA amount acquired from HPLC and fluorescence measurements, we found that the calculated data for L-DOPA from different methods correlated very well, thus confirming that Resa-Sulf is feasible for practical determination of L-DOPA in real samples. A commercially available source, DOPA Mucuna Veg Capsules, was purchased from Now Foods and used without further treatment.…”

Fluorescence Sensing of Caffeine in Tea Beverages with 3,5-diaminobenzoic Acid

“…Jordan Smith et al have demonstrated a fluorescence approach for the rapid, simple and selective detection of caffeine in real tea beverages using aspirin as probe [27]. Wang et al reported the first BODIPY-based fluorescence turn-on caffeine sensor working in aqueous solution, which provided the ideas and basis for my subsequent experiments [28].…”

Molecular recognition of caffeine in solution and solid state

“…Caffeine competitively inhibits different adenosine receptors and their associated G protein to make a person feel alert. A mild stimulant of the central nervous system, caffeine also stimulates cardiac muscle, relaxes smooth muscle, increases gastric secretions, and produces diuresis [1,2].…”