Drug-delivery carriers must endure harsh pH conditions in the gastrointestinal tract and still maintain a high drug loading (DL) for oral therapeutic drugs to be effectively delivered to the colon area. In this research, a pH-sensitive drug-delivery system with an enhanced DL was developed by the coating of 5-fluorouracil (5-FU)-loaded poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) with Eudragit S100 with an oil-in-oil solvent evaporation technique. The enhanced DL and encapsulation efficiency were achieved by the optimization of the fabrication parameters and by the use of particles of a proper size. A DL of 5.8% was obtained by a moderate initial drug feeding, a high volume ratio of the outer water phase to the organic phase, and by the adjustment of the pH value of the outer aqueous phase to the isoelectric point of 5-FU. An in vitro drug-dissolution test showed that the coating of the Eudragit S100 microspheres could effectively prevent drugs from being released in an environment with a pH lower than 7. The PLGA NPs showed an initial burst release followed by a slow and sustained release over an extended period of over 120 h at pH value of 7.4. Therefore, the prepared systems have great potential for practical applications in the treatment of colorectal cancer.

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Non-invasive characterization and observation of synthetic membranes is an important practice to monitor the performance of membrane process. Primarily there are two techniques -optical and non-optical for this purpose. Among them, X-ray computed tomography, as a non-optical technique, has been extensively used for the measurement of fibre distribution and air pockets trapped in the modules. However, the micro resolution of most commercial systems has limited its application which can hardly be used for the sub-micro characterization of membrane processes. A novel micro and nano characterization method is introduced in the current work by exploring an innovative development of the X-ray ultramicroscope (XuM) and micro-tomographic techniques. The XuM, based on using a scanning electron microscope as host, provides a new approach to X-ray projection microscopy. It has demonstrated the ability to characterize very small features in objects, down to of order 100 nm, including the use for dry, wet and even liquid samples. It can also distinguish objects with very subtle difference in density.