A novel time-gated luminescent ruthenium(II) complex probe for highly sensitive detection of methylglyoxal in foods and complex biological samples.

Methylglyoxal (MGO), a highly reactive dicarbonyl compound, is not only a potentially harmful substance in high-sugar foods, but also an important biomarker associated with diabetes and its complications. However, accurate determination of MGO is severely hampered by intense background autofluorescence arising from complex biological and food matrices. To address this challenge, we developed a turn-on luminescent probe, Ru-DTR, by integrating a ruthenium(II) -phenanthroline complex with an o-phenylenediamine recognition unit. The probe exhibits a large Stokes shift, excellent aqueous solubility, and a long emission lifetime (>300 ns), which are inherent photophysical metrics of transition metal complexes. Benefiting from its long-lived luminescence, Ru-DTR can be coupled with time-gated luminescence spectroscopy to efficiently suppress short-lived autofluorescence from complex samples, thereby eliminating background interference and ensuring high sensitivity and accuracy. The probe shows high selectivity and sensitivity toward MGO, with a low detection limit of 53 nM. Its low cytotoxicity and good cell membrane permeability enable high-contrast imaging of exogenous MGO in live HepG2 cells. Moreover, by accurately quantifying MGO levels in various food samples (such as syrups and honey) and in human serum and ocular fluids via time-gated luminescence detection, we validated the practical applicability of this probe in real matrices. This work provides a powerful and reliable tool for MGO monitoring in food safety control, and clinical diagnosis.