Synthesis of benzimidazolones by immobilized gold nanoparticles on chitosan extracted from shrimp shells supported on fibrous phosphosilicate

We demonstrate the synthesis of benzimidazolones from o-phenylenediamines and CO2 in the presence of gold nanoparticles supported on a composite material based on microcrystalline chitosan from shrimp shells and fibrous phosphosilicate.

Chitosan in the control of rose powdery mildew and downy mildew

Microcrystalline chitosan at concentrations from 0.025% to 0.2% was evaluated in the control of Sphaerotheca pannosa var. rosae and Peronospora sparsa. Shrubs were sprayed with chitosan 4 times at weekly intervals. Depending on the concentration used, chitosan reduced development of powdery mildew from 43.5% to 77% and its effectiveness was similar to triforine at concentration 0.03% (standard). Observations of rose leaves under light microscopic, which had been done 24 h after spraying showed, that chitosan caused strong hyphae deformation which almost completely collapse. Cell walls of the pathogen were sunken, corrugated and longitudinally cracked. When applied against P. sparsa effectiveness of the compound at concentration 0.0625% was similar like oxadixil at dose 0.016% (standard) and ranged from 55% to 74%. Efficacy of chitosan decreased with increasing of its concentration.

Evaluation of Microcrystalline Chitosan and Fibrin Membranes as Platelet-Derived Growth Factor-BB Carriers with Amoxicillin

The aim of this study was to describe the mechanical and sorption features of homogeneous and composite membranes which consist of microcrystalline chitosan (MCCh) and fibrin (Fb) in various proportions as well as thein vitrokinetics of platelet-derived growth factor-BB (PDGF-BB) released from ten types of membranes in the presence or absence of amoxicillin (Am). The films were characterized by Fourier transform infrared (FTIR) spectroscopy, mechanical tests: breaking strength (Bs) and elongation at break (Eb), as well as SEM images, and swelling study. The influence of the form of samples (dry or wet) on Young’s modulus (E) was also examined. The homogeneous MCCh (M1) and composite M3 and M4 (MCCh : Fb = 2 : 1 and 1 : 1) membranes were characterized by good sorption properties and higher mechanical strength, when compared with Fb (M2) membrane. Connecting MCCh with Fb decreases release of PDGF-BB and increases release of Am. The most efficient release of PDGF-BB was observed in the case of M4 (the optimum MCCh : Fb ratio was 1 : 1) membrane. It was found that the degree of PDGF-BB release from the membrane is influenced by the physicochemical and mechanical characteristics of the films and by its affinity to growth factor PDGF-BB.

Evaluation of physicochemical and mechanical properties of polymeric formulations for use in the oral cavity

The aim of this research was to create and investigate a formulation that could be placed within post-extraction alveolus. The main material used in this work is a natural polymer, known as microcrystalline chitosan (MCCh). It was formulated as an aqueous hydrogel with the addition of the cross-linking agent (CaCl2) and various plasticizers (propylene glycol, glycerol and sorbitol). The swelling of the preparations was tested by three different methods under completely different acceptor fluids such as distilled water, phosphate buffer and simulated saliva. The pH was measured on the surfaces of each formulation, as well as the pH of the acceptor fluids; evidently, both of them had a similar pH to that of the oral cavity. Additionally, mechanical properties of the tested materials such as hardness, springiness and cohesiveness were evaluated. Based on research, the best compositions of materials were chosen to obtain preparations of the desired geometry and mechanical characteristics. The results from the study are able to prove that MCCh not only creates a neutral environment within the oral cavity but also, due to its significant absorptive properties, can reduce exu date and po ten tially be considered as a new carrier for medicinal substances used in dental implantation and management.