Rational design of large flat nitrogen-doped graphene oxide quantum dots with green-luminescence suitable for biomedical applications

Rational synthesis and simple methodology for the purification of large (35–45 nm in lateral size) and flat (1.0–1.5 nm of height) nitrogen-doped graphene oxide quantum dots (GOQDs) are presented. The methodology allows robust metal-free and acid-free preparation of N-GOQDs with a yield of about 100% and includes hydrothermal treatment of graphene oxide with hydrogen peroxide and ammonia. It was demonstrated that macroscopic impurities can be separated from N-GOQD suspension by their coagulation with 0.9% NaCl solution. Redispersible in water and saline solutions, particles of N-GOQDs were characterized using tip-enhanced Raman spectroscopy (TERS), photoluminescent, XPS, and UV-VIS spectroscopies. The size and morphology of N-GOQDs were studied by dynamic light scattering, AFM, SEM, and TEM. The procedure proposed allows nitrogen-doped GOQDs to be obtained, having 60–51% of carbon, 34–45% of oxygen, and up to 7.2% of nitrogen. The N-GOQD particles obtained in two hours of synthesis contain only pyrrolic defects of the graphene core. The fraction of pyridine moieties grows with the time of synthesis, while the fraction of quaternary nitrogen declines. Application of TERS allows demonstration that the N-GOQDs consist of a graphene core with an average crystallite size of 9 nm and an average distance between nearest defects smaller than 3 nm. The cytotoxicity tests reveal high viability of the monkey epithelial kidney cells Vero in the presence of N-GOQDs in a concentration below 60 mg L⁻¹. The N-GOQDs demonstrate green luminescence with an emission maximum at 505 nm and sedimentation stability in the cell culture medium.

This paper reveals the methodology for robust preparation of purified nitrogen-doped graphene oxide quantum dots with non-cytotoxic activity against monkey epithelial kidney cells (Vero ATCC® CCL-81™).     

Occurrence of aflatoxin M1 in raw milk collected from traditional dairies in Morocco

A survey of the presence of aflatoxin M1 (AFM1) was carried out on eight traditional dairies belonging to four sectors of Fez city situated in the northern center of Morocco. Raw milk samples were collected between October 2009 and September 2010, and analyzed by LC-fluorescence detection after immunoaffinity purification. AFM1 was detected in 13 out of 48 samples (27%) at concentrations ranged between 10 and 100 ng/l. Within these positive samples, four (∼8% of the total) were above the European legislation limit of 50 ng/l. This study revealed a variation of contamination from one sector to another with a higher incidence in milk samples collected in autumn compared to those collected in other seasons suggesting a link between feeding practices, such as the use of silage and AFM1 contamination. This is the first report on AFM1 contamination in raw milk directly collected from Moroccan traditional dairies. The levels of contamination found justify more detailed and continuous monitoring to assess the public health implication and reduce consumers’ exposure to AFM1.     

Atti SUN -Laparoscopic management of sacral neurinoma causing hydronephrosis

We report the case of a sacral neurinoma, which presented with mild hydronephrosis, due to compression of the right ureter, in a 71-yr old woman admitted to our hospital with recurrent urinary tract infections. CT and MRI detected a 4 x 4 cm mass pressing on the right ureter at the sacral level, in continuity with the second sacral foramen. Given this finding, the mass was thought to be of presumable neurogenic origin. In order to both reach a conclusive diagnosis and relieve the compression of the ureter, a laparoscopic resection of the mass was performed. Surgery was successful and the pathologic examination revealed a sacral Antoni A neurinoma. Neurinomas, also called Schwannomas, are uncommon benign nerve sheath tumors arising from Schwann cells. Their diagnosis can be extremely difficult due to their aspecific symptoms and the lack of pathognomonic characteristics on imaging exams. Therefore, histopathologic evaluation is essential in establishing the diagnosis. Surgical resection seems to be the best approach, both for diagnostic and therapeutic purposes.     

A regional model (Northeastern Brazil) of induced mal-nutrition delays ontogeny of reflexes and locomotor activity in rats

Abstract

The aim of this study was to investigate the effects of malnutrition, induced by a regional basic diet (RBD), on motor development. RBD is a 7.87%-protein diet based on aliments typical of Northeastern Brazil, elaborated after nutritional investigation by Teodosio et al. (1979). Female rats were treated with RBD during lactation. The reflex ontogenesis and the development of locomotor activity in their offspring were assessed. Malnourished (MN) rats showed a delay in reflex maturation and in locomotor activity evolution. The decreased locomotor activity may be related to the reduced movement experiences induced by the delay in the reflex maturation. Occurring during the critical period of brain development, this fact could jeopardize all the steps in future locomotion evolution. The present results confirm deleterious effects of RDB-induced malnutrition on the somatic development and maturation of the nervous system (NS).