• Chimie/Chimie thérapeutique
  
• Chimie/ou physique
  
• Chimie/Chimie inorganique
  
• Chimie
  
• Physique/Physique/Physique Numérique
  
• Physique/Matière Condensée/Science des matériaux
  

Photodynamic therapy (PDT) is a cancer treatment, which exploits a photosensitizing drug and light to produce reactive oxygen species that can cause selective damage to the target tissue. The second-generation photosensitizer 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (m-THPC) is a widely used, clinically tested, and commercially available drug with the market formulation known as Foscan. m-THPC was used as a starting point to obtain a library of compounds with improved optical properties. Substitution, esterification and Sonogashira coupling reactions were employed to modify the m-THPC skeleton. Aldehyde and carboxylic acid moieties provided the possibility to enhance the two-photon absorption (TPA) cross-section while being suitable synthetic handles in the design of drug delivery systems. Characterization of their linear photophysical properties (fluorescence quantum yield, fluorescence lifetime and singlet oxygen quantum yield) was followed by the evaluation of their potential use in a non-linear absorption regime. The calculated TPA cross-section values indicate even a 2.6-fold enhancement at the TPA maximum (69.3±10.0 GM), compared to m-THPC (26.7±4.0 GM), which proves that functionalization of the m-THPC core leads to the improvement of the non-linear optical properties. Thus, tetrafunctionalized m-THPC derivatives are promising candidates for application in two-photon induced PDT.

We have elaborated a new preparation method of ternary AgInS2 and alloyed quaternary AgInS2-ZnS nanocrystals which consisted of two consecutive injections of sulfur (S dissolved in oleylamine, OLA) and then silver (AgNO3 or Ag2CO3 dissolved in dichlorobenzene, DCB) precursors to a mixture of indium(III) chloride, zinc stearate and 1-dodecanethiol (DDT) dissolved in 1-octadecene (ODE). In these conditions nucleation of cubic In2S3 seeds took place followed by the growth of orthorhombic AgInS2 or alloyed AgInS2-ZnS cubic phases to yield a heterodimer type of nanocrystals. In both types of nanocrystals clearly separated photoluminescence peaks could be observed, confirming their heterogenic nature. The first one at 430 nm originated from the luminescence of the In2S3 phase. The second one was ascribed to the presence of ternary Ag-In-S or quaternary Ag-In-Zn-S phases and its position, within the spectroscopic range from 515 nm to 710 nm, strongly depended on the nanocrystals composition. The registered two-dimensional excitation-emission topographical maps clearly indicated that the observed emissions in two different spectral regions were related to the excitations in the same spectral range (300-400 nm), however their photoluminescence mechanisms were distinctly different. The photoluminescence lifetime of 3 ns measured for the emission at shorter wavelengths was typical of the simple mechanism of excitons radiative recombination in the In2S3 phase. Significantly longer lifetime of the longer wavelengths emission (26 s) seemed to clearly indicate that in this case the photoluminescence mechanism was more complex, involving exciton trap states whose positions depended on the composition of the ternary (or quaternary) phase.

An exocyclic π-extension of phenanthriporphyrin reduces the macrocyclic antiaromaticity of the formed expanded carbaporphyrinoids.

Carbon-based dots have been attracting much attention as potentially superior alternatives to more conventional semiconductor (e.g. cadmium-based) nanoparticles, due to their fascinating optical properties, chemical and photochemical stability, a unique environment-friendliness, and the versatility of fabrication routes. So far, different commercial materials and organic compounds were considered as carbon precursors for the syntheses but in many cases there are issues with their homogeneity or the fabrication that may require high-temperature conditions. We report on a simple low-cost procedure to produce hydrophilic and hydrophobic fractions of non-conjugated carbon-rich polymer dots (PDs) with the average diameter of 2-4 nm (hydrophilic PDs) and ca. 6 nm (hydrophobic PDs), involving acetone as carbon precursor. The as-obtained PDs reveal the greenish-blue photoluminescence (PL) that is characterized by high PL quantum yields (∼5-7%) and complex kinetics of the PL decays with the average lifetimes estimated to be 3.5 ns. Such luminescent acetone-based PDs may have potential in several application fields, including sensing and bioimaging.