During drug discovery and development the thermodynamics and kinetics of crystal form transitions must be studied and the fundamental properties of polymorphs must be identified. However, despite the accumulation of knowledge and experimental evidence that support the understanding of crystallization, its predictability still presents significant challenges. With the continuous development of new drug delivery technologies, even more complex situations arise such as difficult cases of polymorph selection, co-crystallization of different molecules, and manipulation of the crystallization environment for example amorphous solids. This review covers some fundamental thermodynamics and kinetics of simple system, before the discussions consider at these special cases and how the manipulation of thermodynamic and kinetic processes has increased our knowledge, understanding and application of crystallization science during the drug development process.
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Abstract: Chitosan Grafted Silica (CGS) material was prepared by using tetraethyl-orthosilicate as grafting and/or cross linking agent. The structure of the material was characterized by SEM (Scanning Electron Microscopy), FTIR (Fourier transform infrared Spectroscopy), and BET (Brunauer, Emmett and Teller) analysis. The higher sorption potential of synthesized material for organo-chlorine pesticides (OCPs) like DDT and DDE was attributable to its large surface area, porous rigid structure and active sites such as –OH, –NH2, and –CONH2. Most removal of DDT (94±2.9%) and DDE (86 ±1.8%) was achieved at 40°C and pH 6 with agitation of 2 and 3 hours, respectively. The thermodynamics data suggested an endothermic, spontaneous and higher stable sorption process with no structural changes at the solid-solution interface. The ΔG value was increased with an increase in temperature up to 40°C, indicating a greater driving force ensuing a higher sorption capacity. The co-efficient of correlation (R2) suggested that the sorption data was best fitted in Freundlich isotherm rather than the Langmuir isotherm, indicating a multilayer sorption. The Freundlich sorption isotherm proposed a favorable sorption of DDT as compare to DDE. The developed method was applied to real industrial waste at laboratory level. The experimental data revealed that developed method might be employed for the removal of DDT and DDE from aqueous industrial effluents before discharging them into water bodies.
Article Title:Enhanced Luminescent Properties of Solution Combustion Synthesized Nanocrystalline Y3Al5O12:Eu3+ Phosphors
Author(s): Sumei Wang, Xurong Zhao, Shengming Zhou, Limin Zhou and Guodong Xia
Author(s): Shunan Shan, Xuhua Hu, Siyu Ni, Kai Li, Jing Li and Xingping Zhou
Alpha-fetoprotein ( α-FP, AFP) was the only serological marker currently available for the detection of hepatocellular carcinoma (HCC). As a novel biological luminescent label, the favorable properties of water-soluble CdTe quantum dots (QDs) have advantages over conventional fluorescent materials. Meantime, the magnetic separation technique has widely been applied to various aspects in biotechnology in recent years. In this paper, CdTe QDs and dextran–Fe3O4 magnetic nanoparticles were both applied on immunoassay for the determination of AFP concentration. Firstly, a mouse anti-human AFP antibody (primary antibody) was immobilized on magnetic nanoparticles, which were used as solid support. Secondly, another mouse anti-human AFP antibody (secondary antibody) was attached to the surface of the CdTe QDs via electrostatic interaction. It was found that when the pH value was 6.0, the volume ratio of CdTe (3 ×10-4 mol/L) to antibody (2 mg/mL) was 50:3, and the reaction time was more than 10 min, the complex of the secondary antibody and CdTe was formed and the strongest PL intensity was obtained. Thirdly, the above two complexes were conjugated with a serial of AFP concentrations. Then the relationship between the PL intensity and the AFP concentration was determined and the calibration equation— Y=k(X-9.31)/V—was obtained. Finally, ten samples of human serum were tested based on this equation. The results, to a large extent, were consistent with those obtained by Time-resolved Fluorescence. More importantly, the current method could be applied in many other antibody-antigen systems.
Author(s): Fei-Peng Jiao, Lei Zhou, Wei-Jie Yang, Jin-Gang Yu and Xiao-Qing Chen
Sudan dyes are toxic or carcinogenic even at low concentrations, which are illegally used as additives in food products to maintain their red color and thus stimulate sales of these products in the market recently. A facile adsorption procedure for the removal of Sudan I and II in n-hexane using oxidized multi-walled carbon nanotubes (O-MWCNTs) is presented in this paper. The effect of absorption conditions including absorption time, amount of adsorbent, initial concentration of Sudan I and II was examined. Two isotherm models were used to describe the adsorption equilibrium, while three kinetic models were applied to evaluate the adsorption process. The adsorption process and equilibrium for Sudan I and II were all proved to be fitted by the Langmuir model and second-order kinetic model. The O-MWCNTs possessed fast kinetics for Sudan I and II from n-hexane solvent with each saturation time of <30 min, and correspondingly the maximum adsorption capacities for Sudan I and II were 41.408 mg/g and 47.037 mg/g, respectively.