Crosslinked Chitosan Nanoparticles with Muco-Adhesive Potential for Intranasal Delivery Applications.

Intranasal drug delivery is convenient and provides a high bioavailability but requires the use of mucoadhesive nanocarriers. Chitosan is a well-established polymer for mucoadhesive applications but can suffer from poor cytocompatibility and stability upon administration. In this work, we present a method to obtain stable and cytocompatible crosslinked chitosan nanoparticles. We used 2,6-pyridinedicarboxylic acid as a biocompatible crosslinker and compared the obtained particles with those prepared by ionotropic gelation using sodium tripolyphosphate. Nanoparticles were tested to evaluate the size and the surface charge, as well as their stability in storage conditions (4 °C), at the nasal cavity temperature (32 °C), and at the body temperature (37 °C). The crosslinked chitosan nanoparticles showed a size around 150 nm and a surface charge of 10.3 mV ± 0.9 mV, both compatible with the intranasal drug administration. Size and surface charge parameters did not significantly vary over time, indicating the good stability of these nanoparticles. We finally tested their cytocompatibility in vitro using SHSY5Y human neuroblastoma and RPMI 2650 human nasal epithelial cells, with positive results. In conclusion, the proposed synthetic system shows an interesting potential as a drug carrier for intranasal delivery.

The 2D:4D ratio is associated with performance in the 'TEACCH program' of subjects with autism spectrum disorder.

Problems arising on the autistic spectrum are more common in male individuals, leading scholars to attempt to determine whether there is a correlation with testosterone levels to which fetuses were exposed during intrauterine life. The aim of the present study was to investigate, through the digit ratio technique, the possible correlation between testosterone exposure during intrauterine life and the achievement of predetermined objectives during the educational program Treatment and Education of Autistic and Related Communication Handicapped Children (TEACCH) in a group of subjects with different forms of autism. The results showed a positive correlation of the TEACCH program and 2D:4D ratio. Therefore, we hypothesize that a base screening may be useful to pinpoint the optimal teaching strategies to obtain the best possible performance from each subject.