Direct pulp capping with novel nanostructural materials based on calcium silicate systems and hydroxyapatite

Summary Introduction Direct pulp capping is an important therapeutic method that has goal to provide formation of dentin bridge and healing process of the pulp. The aim of this study was to investigate the effects of new nanostructural materials based on calcium silicate systems and hydroxyapatite on exposed dental pulp in Vietnamese pigs. Material and Methods The study was conducted on 30 teeth of two Vietnamese pigs (Sus scrofa verus). On buccal surfaces of incisors, canines and first premolars, class V cavities were prepared with a small round bur and pulp horn was exposed. In the first experimental group (10 teeth) the perforation was covered with new nanostructural material based on calcium silicate systems (CS). In the second experimental group, the perforation was covered with compound of calcium silicate systems and hydroxyapatite (HA-CS) (10 teeth). In the control group, exposed pulp was covered with Pro Root MTA® (Dentsply Tulsa Dental, Johnson City, TN, USA) (10 teeth). All cavities were restored with glass ionomer cement (GC Fuji VIII, GC Corporation, Tokyo, Japan). Observation period was 28 days. After sacrificing the animals, histological preparations were done to analyze the presence of dentin bridge, inflammatory reaction of the pulp, pulp tissue reorganization and the presence of bacteria. Results Dentin bridge was observed in all teeth (experimental and control groups). Inflammation of the pulp was mild to moderate in all groups. Neoangiogenesis and many odontoblast like cells responsible for dentin bridge formation were detected. Necrosis was not observed in any case, neither the presence of Gram-positive bacteria in the pulp. Conclusion Histological analysis indicated favorable therapeutic effects of new nanostructural materials based on calcium silicate systems and hydroxyapatite for direct pulp capping in teeth of Vietnamese pigs.

Synthesis of Silver Nanoparticles with Potential Antifungical Activity for Bamboo Treatment

To increase the durability of bamboo it is important to find an easy method to fill the micro and meso structure of the biological matrix using a nanostructural material with an anti-fungical activity. A colloidal solution of silver nanoparticle (Ag-NPs) is a dispersion of metal nanoparticle in water with a diameter between 5-100 nm. Even if the biological mechanism is not completly understood yet, Ag-NPs show a satisfactory bactericidal and antifungical activity. We present a simple and rapid production of Ag-NPs made by a sol-gel synthesis in flow mode by means of microreactor tecnology through a chemical reduction of AgNO3 with NaBH4 in presence of two different organic ligands: sodium/potassium tartrate and trisodium citrate. The synthesis of Ag-NPs in continuous flow compared to the batch technique allowed to reduce the time of synthesis, facilitating the reproducibility of the process and consequently obtaining NPs with more uniform physical and chemical characteristics. The microorganisms of the genus Aspergillus were used for the microbiological tests. The effect of different Ag-NPs on microbial growth was observed daily. In particular, it was shown that the response of the fungus is inversely proportional to the size of the nanoparticles, cell growth is disrupt depending on the proportion between silver and organic ligand and microbialstatic effect, especially in relation to sporulation stage was also observed.

Birefringence and DNA Condensation of Liquid Crystalline Chromosomes

ABSTRACT DNA can self-assemble in vitro into several liquid crystalline phases at high concentrations. The largest known genomes are encoded by the cholesteric liquid crystalline chromosomes (LCCs) of the dinoflagellates, a diverse group of protists related to the malarial parasites. Very little is known about how the liquid crystalline packaging strategy is employed to organize these genomes, the largest among living eukaryotes—up to 80 times the size of the human genome. Comparative measurements using a semiautomatic polarizing microscope demonstrated that there is a large variation in the birefringence, an optical property of anisotropic materials, of the chromosomes from different dinoflagellate species, despite their apparently similar ultrastructural patterns of bands and arches. There is a large variation in the chromosomal arrangements in the nuclei and individual karyotypes. Our data suggest that both macroscopic and ultrastructural arrangements affect the apparent birefringence of the liquid crystalline chromosomes. Positive correlations are demonstrated for the first time between the level of absolute retardance and both the DNA content and the observed helical pitch measured from transmission electron microscopy (TEM) photomicrographs. Experiments that induced disassembly of the chromosomes revealed multiple orders of organization in the dinoflagellate chromosomes. With the low protein-to-DNA ratio, we propose that a highly regulated use of entropy-driven force must be involved in the assembly of these LCCs. Knowledge of the mechanism of packaging and arranging these largest known DNAs into different shapes and different formats in the nuclei would be of great value in the use of DNA as nanostructural material.