2006 ที่น้องแอนทำ.pmd - Mahidol University

Mahidol University Abstract of International Publications 2006
6
by a porous membrane diffusion scrubber at 0.2 L/min with quantitative collection
efficiency, derivatized on – line to 1 – sulfonatoisoindole, and measured by fluorometry.
In the typical range for ambient ammonia (0 – 20 ppbv), response is linear (r(2) =
0.9990) with a S/N = 3 limit of detection of 135 pptv (15 nM for 500 mu L of injected
+ NH (aq)) with an inexpensive light emitting diode photodiode – based detector.
4
Automated operation in continuously repeated, 8 – min cycles over 9 days shows
excellent overall precision (n = 1544 P – NH3 = 5 ppbv, RSD = 3%). Precision for liquid
+ – phase injections is even better (n = 1520, [NH (aq)] = 2.5 mu M, RSD = 2%). The
4
response decreases by 3.6% from 20 to 80% relative humidity.
No.17
Author(s) : Anal AK, Stevens WF, Remunan – Lopez C.
Title : Ionotropic cross – linked chitosan microspheres for controlled release of ampicillin.
Source : International Journal of Pharmaceutics. 312 (1 – 2): 166 – 173, 2006 (Apr).
Document Type : Article.
Keywords : Ampicillin, Chitosan microspheres, Controlled release, Emulsification – solvent
evaporation, Spray – drying, Tripolyphosphate.
Abstract : The solubility of non cross – linked chitosan in weak acid solutions restricts its utility
in microspheres for drug delivery. The primary aim of this study was to produce
pentasodium tripolyphosphate cross – linked chitosan microspheres with higher acid
resistance for controlled release of ampicillin. The microspheres were prepared by
two different microencapsulation procedures (by emulsification and by spray – drying)
and characterized by their particle size, surface morphology, stability, drug entrapment
efficiency and drug release. The size of the microspheres was < 10 mu m with a
narrow size distribution. The entrapment of ampicillin in the microspheres was more
than 80%. Stability of uncross – linked and cross – linked microspheres was affected
by the pH of simulated gastric fluid (SGF, pH 1.2) and simulated intestinal fluid (SIF,
pH 7.5). The inclusion of the enzymes pepsin and pancreatin did not affect the stability
of the microspheres. The inclusion of lysozyme in phosphate buffer saline resulted in
increased solubilization. The release of the drug was affected by cross – linking of
microspheres with tripolyphosphate (TPP). The cross – linked microspheres were
more stable in simulated gastric fluid and showed slower but sustained release of
ampicillin. The antimicrobial activity of the released ampicillin was confirmed by
Staphylococcus aureus bioassay.
No.18
Author(s) : Anantachoke N, Makha M, Raston CL, Reutrakul V, Smith NC, Saunders M.
Title : Fine tuning the production of nanosized beta – carotene particles using spinning disk
processing.
Source : Journal of the American Chemical Society. 128 (42): 13847 – 13853, 2006 (Oct).
Document Type : Article.
Keywords : Process intensification, Reactor, Water, Nanodispersions, Calixarenes, Stability,
Spheres.
Abstract : Nanoparticles of trans – beta – carotene are accessible using spinning disk processing
(SDP), by varying the reaction conditions and the choice of surfactant, macrocyclic
amphiphiles, sulfonato – calyx [4, 5, 6, 8] arenes, and alpha, beta – cyclodextrins. SDP
ensures rapid mixing and fast kinetics, and nanoparticles of the carotene formed in
the presence of the calixarenes are stable with respect to extraction of the carotene
into an organic solvent, unlike in the presence of the cyclodextrins. Insight into the
supramolecular structure of the carotene nanoparticles has also been established.
The mean particle sizes (dynamic light scattering, DLS) have been optimized at 40(2)
and 56(1) nm and 71.4(6) and 82(1) nm, respectively, for each sulfonato – calix[5,6
and 4,8] arene, whereas the cyclodextrins form nanoparticles with a mean diameter
of 71(1) and 68.5(6) nm, respectively. Zeta – Potential studies show stability of all the
colloidal dispersions at pH > 4 with values below –30 mV. UV – visible spectroscopy
shows a blue shift indicative of H – aggregates of the carotene within the nanoparticles.
The surface area derived from BET studies is 39.12 m(2)/g corresponding to particles
of 76.7(5) nm in diameter, in agreement with sizes obtained from DLS and TEM
measurements.