time resolved florescence

With this instrumentation the decay time of a fluorescence signal can be measured by the Time Correlated Single Photon Counting technique. It has a pulsed laser source (λem= 375 nm; ν0= 40 MHz; FWHM: 40 ps), a computer controlled Peltier thermostatted cell holder (-10-80°C), a stepped motor monochromator (200-800 nm interval), a fast single photon detector and an TCSPC acquisition board (0.8 ps time resolution). This instrumentation allows to measure fluorescence lifetimes (τ) spanning from ps (10-12 s) to μs (10-6 s); therefore, it can be used with a broad range of fluorophores. In the lab where it is located, polymeric nanoparticles assemblies (NP) hosting the anticancer antibiotics doxorubicin -DX- and epirubicin -EPI- (both in the form of hydrochloride to increase their water solubility) are prepared, with the aim of testing them as drug-carriers against tumours. Since the NP core is hydrophobic, the drug migration (assisted by anionic bile salts) from the water phase to the NP interior is coupled to a progressive decrease in the drug lifetime (for example, τ_DX^water=1.00 ns;τ_DX^NP=4.30 ns).