Differential properties and effects of fluorescent carbon nanoparticles towards intestinal theranostics.

Given the potential applications of fluorescent carbon nanoparticles in biomedicine, the relationship between their chemical structure, optical properties and biocompatibility has to be investigated in detail. In this work, different types of fluorescent carbon nanoparticles are synthesized by acid treatment, sonochemical treatment, electrochemical cleavage and polycondensation. The particle size ranges from 1 to 6 nm, depending on the synthesis method. Nanoparticles that were prepared by acid or sonochemical treatments from graphite keep a crystalline core and can be classified as graphene quantum dots. The electrochemically produced nanoparticles do not clearly show the graphene core, but it is made of heterogeneous aromatic structures with limited size. The polycondensation nanoparticles do not have CC double bonds. The type of functional groups on the carbon backbone and the optical properties, both absorbance and photoluminescence, strongly depend on the nanoparticle origin. The selected types of nanoparticles are compatible with human intestinal cells, while three of them also show activity against colon cancer cells. The widely different properties of the nanoparticle types need to be considered for their use as diagnosis markers and therapeutic vehicles, specifically in the digestive system.

Characteristics of continuous esophageal pH-metering in infants with gastroesophageal reflux and apparent life-threatening events.

Episodes of apnea during the first year of life have been classified with the term "Apparent Life-Threatening Events" (ALTE). Gastroesophageal reflux (GER) has been accepted to be one of the factors which can favor ALTE. The aim of this work is to study the continuous 24 h gastroesophageal pH-metering (fundamentally the Reflux Index [RI] and the Area Under Curve [AUC] parameters in three different periods of time: total pH-metering, pH-metering excluding the first two post-prandial hours, and pH-metering during sleep time, for 24 infants, 14 with ALTE and 10 without it). Between these two groups (with and without ALTE) there were no significant differences in the total pH-metering concerning the RI (2 +/- 1.2 vs 5.6 +/- 7.5 p > 0.05) and concerning the AUC (24.9 +/- 14.4 vs 67.4 +/- 84 p > 0.05), but in the analysis of the sleep period, the RI (p < 0.05) and the AUC (p < 0.01) both showed significant differences in the group of infants without ALTE. These results confirm that pH-metering study during sleep is the procedure of choice for recognizing infants with ALTE.