A series of four water-soluble benzazole dyes that emit fluorescence by the excited state intramolecular proton transfer (ESIPT) mechanism were structurally characterized by Fourier transform infrared spectroscopy (FTIR), 1H and 13C nuclear magnetic resonance (NMR) attached proton test (APT) and mass spectrometry. Their photophysical properties were systematically studied by UV-absorption and fluorescence emission. Some photophysical parameters were obtained by semi-empirical PM3 and ZINDO methods, and related to experimental photophysical data. Changes in the absorption and fluorescence emission spectra as well as conformational equilibrium between different species were investigated in solvents of different polarities and under different pH conditions. These benzazole dyes emit dual fluorescence emission in the blue-orange region with a Stokes shift between 2617-12337 cm-1. In general, these dyes are potentially interesting for studies of biological systems in an aqueous environment due to the presence of groups that increase aqueous solubility and reactivity with biomolecules. The present dyes were successfully used as new probes by means of direct staining of larvae. The obtained results indicate that these fluorescent dyes permit a quick, easy and selective visualization of larvae.

Cryptosporidium spp is a common intestinal pathogen of animals and humans. It may have an important economic impact on farms and cause potentially zoonotic infections. Fecal specimens were collected from 331 domestic animals (81 beef cattle, 50 sheep, 100 pigs and 100 dogs) and checked for the presence of Cryptosporidium oocysts by way of Ziehl Neelsen and auramine staining methods. An overall positivity rate of 7.5% (25/331) was found, with rates of 10% (10/100) among the dogs and 18.5% (15/81) among the beef cattle. The feces of sheep and pigs tested negative. In beef cattle, 15 and 12 positive samples were detected by the auramine and Ziehl Neelsen staining techniques, respectively, with no statistically significant difference between the two methods. In dogs, the same number of positive samples was found by both techniques