Dopamine-loaded chitosan nanoparticles: formulation and analytical characterization

The formulation and characterization of dopamine (DA)-loaded chitosan nanoparticles (CSNPs) are described as preliminary steps for the development of potential DA carrier systems intended for Parkinson’s disease treatment. For this purpose, CSNPs were firstly produced and, afterwards, they were incubated in a DA aqueous solution to promote neurotransmitter loading. The characterization of the resulting nanoparticles started with Fourier transform infrared spectroscopy analysis to ascertain the presence of DA in the nanocarrier, whereas X-ray photoelectron spectroscopy analysis provided evidence of the localization of DA on the nanoparticle surface. A quartz crystal microbalance with dissipation monitoring (QCM-D) was then exploited to investigate both swelling of CSNPs and interaction of DA with CSNPs. In particular, the QCM-D revealed that this interaction is fast and so this allows a stable nanostructured system to be obtained.     

The effect of tannins on Mediterranean ruminant ingestive behavior: the role of the oral cavity

Sheep, cattle and goat are domestic ruminants of significant economic interest in the Mediterranean region. Although sharing the same pasture ranges, they ingest different plants and plant parts and, consequently different levels of tannins. This suggests an ability to detect and adapt ingestion according to animal physiological limits of tolerance for plant secondary metabolites. This review will detail the effects of dietary tannins on feeding behavior, and the role of the oral cavity in this process, with focus on such ruminant species. The role of salivary protein profile in tannin perception in the oral cavity, and as a defense mechanism, will be discussed.     

DITHIOPHOSPHORIC ACIDS AND TETRAPHOSPHORUS DECASULFIDE IN THE SYNTHESIS OF BORON DITHIOPHOSPHATES

Abstract

The reactions of O,O-dialkyl dithiophosphoric acids with triisobutyl borate, ammonium O,O-diisobutyl dithiophosphate with fluorodiisobutyl borate, and tetraphosphorus decasulfide with triisobutyl borate were studied. On the basis of these studies, new boron derivatives of dithiophosphoric acids were obtained. Low frequency ultrasonic irradiation (22 kHz, power 130 W) leads to reduction in reaction temperature and time in the reactions studied.     

Kinetics and Mechanism of the Kabachnic-Fields Reaction

Abstract

The Kabachnic-Fields reaction is one of the most important methods of synthesis of functionally substituted derivatives of tetracoordinated phosphorus with P-C bond. At the same time mechanism of this important and interesting reaction practically has not been investigated.     

“For Asia Market Only”: A Green Tattoo Ink between Safety and Regulations

Due to the increasing tattoo practicing in Eastern countries and general concern on tattoo ink composition and safety, the green tattoo inks Green Concentrate by Eternal, for European and “for Asia Market Only” were analyzed, under the premise that only the former falls under a composition regulation. A separation of the additives from the pigment was carried out by successive extraction in solvents of different polarities, i.e., water, acetone and dichloromethane. The solid residues were analyzed by IR and Raman spectroscopies, the liquid fractions by GC/mass spectrometry. The relative pigment load and element traces were also estimated. We found that the European and the Asian inks are based on the same pigment, PG7, restricted in Europe, though at different loads. They have a similar content of harmful impurities, such as Ni, As, Cd and Sb and both contain siloxanes, including harmful D4. Furthermore, they have different physical-chemical properties, the European ink being more hydrophilic, the Asian more hydrophobic. Additionally, the Asian ink contains harmful additives for the solubilization of hydrophobic matrices and by-products of the phthalocyanine synthesis. Teratogenic phthalates are present as well as chlorinated teratogenic and carcinogenic compounds usually associated to the laser treatment for removal purposes, to a larger extent in the European ink. The composition of the inks does not seem to reflect regulatory restrictions, where issued.     

Disilyl dithiophosphonates in the synthesis of open chain and cyclic organothiophosphorus compounds

O-(Trimethylsiloxy)alkyl S-trimethylsilyl aryldithiophosphonates 7a–d were obtained by the reaction of 2,4-diaryl-1,3,2,4-dithiadiphosphetane-2,4-disulfides 5a,b with disilyl derivatives of glycols 6a,c and salicyl alcohol 6b . The reactions of mixed O,S-bis(trimethylsilyl) 2,4-di(3,5-di-tert-butyl-4-hydroxyphenyl)dithiophosphonate 1 and S-silyl aryldithiophosphonates 7a,b with S,S-diethyldithiodiphenylgermane 2 , dichlorodiphenylgermane 8a , and dichlorodiphenylstannane 8b were studied. The structure of hexaphenyl-2,4,6,1,3,5-trithiatrigerminane 11 was established by X-ray single crystal diffraction. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:225–232, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20009     

New methods of synthesis of boron,germanium, and tin derivatives of pentavalent phosphorus thioacids

The reactions of S‐trimethylsilyl esters of S‐propyl‐4‐methoxyphenyltrithiophosphonic, bis(dialkylamido)dithiophosphoric, and S‐ethyl‐diethylamidotrithiophosphoric acids with trialkyl borates, triorganylbromogermanes, trimethyl(isobutylthio)germane, and trialkylchlorostannanes were studied. On the basis of these studies, new methods of synthesizing S‐boron, S‐germyl, and S‐stannyl derivatives of pentavalent phosphorus thioacids were developed. S‐Diethylaminomethyl O‐isopropyl‐4‐ethoxyphenyldithiophosphonate was obtained by the reaction of the diisopropylboron derivative of the corresponding dithiophosphonic acid with the aminal 6 . © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:27–35, 2002; DOI 10.1002/hc.1103     

Boron derivatives of dithiophosphoric acids

The reactions of tetraphosphorus decasulfide 1 with trialkyl borates 2a,b and O‐isobutyl diphenylborate 2c were studied. On the basis of these studies, a novel method of synthesizing S‐boron derivatives of dithiophosphoric acids was developed. The use of low frequency ultrasonic irradiation (22 kHz, power 130 W) leads to a reduction in reaction temperature and time required for completion of the reactions studied. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:102–106, 2000     

Synthesis and thermal stability of S‐trimethylsilyl esters of tetracoordinated phosphorus amidothioacids

S‐(Diethylamino)dimethylsilyl bis(diethylamido)dithiophosphate 3 was obtained by the reaction of tetraphosphorus decasulfide 1 with bis(diethylamino)dimethylsilane 2a . The reactions of Lawesson's reagent 5 with 2a and the alkyl homologues of Davy's reagent 8a,b with trimethyl(diethylamino)silane 6 were studied. On the basis of these reactions, methods of synthesizing S‐(diethylamino)dimethylsilyl or S‐(diethylamino)diphenylsilyl 4‐methoxyphenyl (diethylamido)dithiophosphonates 7a and 7b and S‐trimethylsilyl S‐alkyl(diethylamido)trithiophosphates 9a,b are described. The optimal reaction conditions and thermal stability of S‐trimethylsilyl S‐ethyl(diethylamido)trithiophosphate 9a were defined by differential thermal analyses. Compound 9a have been decomposed to form 2,4‐bis(diethylamido)‐1,3,2,4‐dithiadiphosphetane‐2,4‐disulfide 10 which structure was established by X‐ray single crystal diffraction. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:670–675, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20231