Fluorescence methods for detecting the kinetics of photosensitizer release from nanosized carriers

International audienceThree approaches to analyzing the rate of release of the photosensitizer meta-tetrahydroxyphenylchlorin (mTHPC) from unilaminar lipid vesicles (ULV) in model biological systems are studied: by excitation energy transfer from probe diphenylhexatriene to mTHPC, by the fluorescence anisotropy of mTHPC, and by photoinduced quenching of the fluorescence of mTHPC. Each of these methods has its characteristic range of sensitivity for measurements of the local concentration of mTHPC in ULV. Fluorescence anisotropy can be used for quantitative determination of the mTHPC yield from ULV for mTHPC:lipid ratios of 1:100 to 1:1000, determining the efficiency of fluorescence quenching of diphenylhexatriene for ratios <1:200, and photoinduced quenching for ratios of 1:10-1:500

Use of UV-C postharvest treatment for extending fresh whole tomato (Solanum lycopersicum, cv. Zinac) shelf-life

The effect of UV-C treatments (0.32, 0.97, 2.56, 4.16 and 4.83 kJ.m(-2) at 254 nm) on the physical-chemical properties [colour, texture, total phenolic content (TPC), weight loss (WL)], and mesophylic counts of whole tomato, was evaluated during 15 days at 10 A degrees C. During storage, the Ctr samples acquired faster red colour than all UV-C samples (higher a* and lower A degrees h values). Comparing texture of Ctr and UV-C samples at 15(th) storage day, an increase of 9 and 8 % on firmness of treated samples at low UV-C intensities (0.32 and 0.97 kJ.m(-2), respectively) was observed. At the end of the storage, Ctr samples showed ca. 4 Log(10) of mesophylic load, and the samples treated at 0.97 and 4.83 kJ.m(-2) revealed the lowest microbial load (1.9 and 3.2 Log(10), respectively). These results indicate that UV-C radiation, at an appropriate dose, combined with low storage temperature (10 A degrees C) are an effective method to preserve the postharvest life of tomato, without adversely affecting quality parameters.info:eu-repo/semantics/publishedVersio