Stability and morphology of Ag nanoplatelets probed by depolarized dynamic light scattering.

The stability of silver nanoplatelet (NP) suspensions prepared with different concentrations of trisodium citrate (TSC) was studied by depolarized dynamic light scattering (DDLS) and UV-vis spectrometry. The morphology of the nanoparticles, as well as the color and stability of the sols, are tuned by the concentration of the capping agent. The nanoparticles prepared with high TSC concentration (>10-4 M) are blue triangular NPs showing a slight truncation of the tips with aging. When low TSC concentrations are used, the color of the sols changes from blue to yellow with aging time and a strong modification of the morphology occurs: the nanoparticle shape changes from triangular to spherical. Remarkably, they show a high degree of anisotropy. The aging process was followed by the UV-vis spectra and by measuring the rotational diffusion coefficient by DDLS, providing information on the nanoparticle size and shape evolution. The high intensity of depolarized signal and the high value of rotational diffusion coefficient suggest that the aging process increases the thickness and the roughness of the nanoparticles.

Chiral separation of terbutaline and non-steroidal anti-inflammatory drugs by using a new lysine-bridged hemispherodextrin in capillary electrophoresis.

A method for the separation of a mixture of terbutaline and non-steroidal anti-inflammatory drugs was developed using capillary electrophoresis with a new hemispherodextrin, ad hoc designed, the lysine - bridged hemispherodextrin (THLYSH). The use of lysine residues to bridge the trehalose capping unit moiety to the cyclodextrin cavity gives rise to a receptor with two long chains with amine nitrogen atoms, whose charge can be easily tuned as a function of the solution pH. The new hemispherodextrin was accurately characterised by ESI-MS and NMR spectroscopy, also highlighting its protonation behaviour. Circular dichroism and ESR spectroscopy measurements were also carried out to test its inclusion ability towards anthraquinone-3-sulfonate and its metal coordination ability towards copper(II) ion, respectively. Analogously to the other hemispherodextrins, the main skill of this new derivative lies in its chiral selector properties, as shown by the separation of the enantiomeric pairs of terbutaline and ibuprofen, flurbiprofen, suprofen and tiaprofenic acid by capillary electrophoresis. The focused use of the solution equilibria involved in the separations made it possible to understand the phenomena occurring in solution, and to finely tune the charge status of the receptor. In this way the chiral separation of the racemic mixture was successfully obtained, even if the receptor was individually used, differently by the other hemispherodextrins previously studied whose chiral separation capabilities are present only if used as binary mixtures.

The 3-amino-derivative of gamma-cyclodextrin as chiral selector of Dns-amino acids in electrokinetic chromatography.

The enantioseparation of the enantiomeric pairs of 10 Dns derivatives of alpha-amino acids was successfully carried out by using for the first time the 3-amino derivative of the gamma-cyclodextrin. The effects of pH and selector concentration on the migration times and the resolutions of analytes were studied in detail. 3-Deoxy-3-amino-2(S),3(R)-gamma-cyclodextrin (GCD3AM) shows very good chiral recognition ability even at very low concentrations at all the three investigated values of pH, as shown by the very large values of selectivity and resolution towards several pairs of amino acids. The role played by the cavity, the substitution site and the protonation equilibria on the observed properties of chiral selectivity, on varying the specific amino acid involved, is discussed.

Computerized tomography of the abdomen and pelvis with peritoneal administration of soluble contrast (IPC-CT) in detection of residual disease for patients with ovarian cancer.

Forty-five ovarian cancer patients were submitted to abdominopelvic computed tomography after intraperitoneal administration of soluble contrast in large fluid volumes (3 liters of normal saline) (IPC-CT), for a total of 66 exams. In all cases standard abdominopelvic CT scanning had previously missed the presence of disease. Peritoneal access was achieved by a temporary Teflon catheter inserted blindly. No major complications related to peritoneal access or fluid administration occurred. Laparotomy was performed in all cases to evaluate accuracy of this new diagnostic procedure. Overall, 32/66 exams showed no abnormal findings. In 9/32 cases persistence of disease was demonstrated by laparotomy. The remaining 34 exams were suggestive of persistence of tumor. In 19 cases CT scan showed nodular images or peritoneal thickness. Persistence of disease was confirmed by laparotomy in all instances. In 15 cases only an abnormal diffusion of soluble contrast into peritoneum (suprahepatic, anterior, or parietocolic region) was demonstrated. In 11/15 persistence of tumor was found at laparotomy. To summarize, IPC-CT revealed persistence of tumor in 30/39 cases (77% sensitivity). Positive results were predictive of persistence of disease in 30/34 cases (88% specificity). This new procedure was able to detect persistence of disease in most of our patients showing negative standard CT (30/39 vs 0/39; P < 10E-8) and its diagnostic accuracy was even better than standard CT+serum tumor markers (30/39 vs 16/39; P < 0.001). In conclusion, IPC-CT could be very effective in monitoring response to treatment and could markedly reduce the number of ovarian cancer patients requiring second-look laparotomy.