Synthesis of pH-responsive hydrogel based on PVP grafted with crotonic acid for controlled drug delivery

In the present study polyvinylpyrrolidone (PVP) was grafted with crotonic acid (CrA) in order to obtain novel hydrogels which are pH – responsive. The grafting was performed by mixing the polymer solution with various concentrations of CrA and applying gamma radiation at different doses. The effects of the preparation conditions such as the irradiation dose and CrA concentration on the gelation process and swelling of the synthesized copolymer were investigated. The hydrogel system was used as carrier for a model drug, ketoprofen, the release behaviour of the drug from the hydrogel was monitored in two different release media (pH 1 and pH 7.2), and released amounts of ketoprofen were followed up spectrophotometrically. The release was low in the acidic medium compared to a better and extended release in the neutral medium suggesting the possibility of using this hydrogel as potential drug carrier to allow targeted release in the intestinal medium

Classification of polyethylene cling films by attenuated total reflectance-Fourier transform infrared spectroscopy and chemometrics

Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) was utilised to analyse nine differently branded cling films. Principal component analysis (PCA) was used to assess the intra-sample variability, i.e. the variation within individual cling film rolls; as well as the inter-sample variability, which explores the variability between different rolls of cling film. Linear discriminant analysis (LDA) was then employed to develop a predictive classification model which gave 100% correct differentiation between three brand groupings of cling film, and accurately classified all of the validation samples obtained from different rolls from the same manufacturers

Effect of processing conditions on in-mold crystallization of poly(L-lactic) acid

Peer reviewed: YesNRC publication: Ye

Modulation of population density and size of silver nanoparticles embedded in bacterial cellulose : via ammonia exposure: visual detection of volatile compounds in a piece of plasmonic nanopaper

The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and from amber to a grey or taupe colour upon fish or meat spoilage exposure. These phenomena are proposed as a simple visual detection of volatile compounds in a flexible, transparent, permeable and stable single-use nanoplasmonic membrane, which opens the way to innovative approaches and capabilities in gas sensing and smart packaging

Nano/micro electro-spun polyethylene terephthalate fibrous mat preparation and characterization

Electro-spun polyethylene terephthalate (PET) fibrous mats are potential substrates for biotechnological and biomedical applications. In this regard, substrate characteristics including, fiber diameter, orientation and mechanical properties play an important role in controlling the interaction of substrate with biological entities. However, few studies reporting the preparation of electro-spun PET substrates with such controlled characteristics have been published. In this study, electro-spun PET fibrous mats with fiber diameters in the nanometer and micrometer range were produced by varying polymer solution concentration and flow rate. Fiber orientation within the mats was also varied by varying collector surface velocities in rotation and translation. Their morphological, mechanical, thermal and structural properties were evaluated as a function of fiber diameter and collector speed using scanning electron microscopy (SEM), a micromechanical tester, differential scanning calorimetry (DSC) and X-ray diffraction (XRD), respectively. Varying polymer solution concentration and flow rate allowed the production of matrices with fiber diameters ranging from 400 nm to 2 \u3bcm. Tensile properties increased with fiber diameter and collector surface velocity. Thermal properties of electro-spun PET fibers were different from the structure of as received raw PET in the form of pellets, revealing an amorphous structure for the entire electro-spun PET. This was also confirmed by XRD analysis. No considerable differences were observed between electro-spun PET fibers, in terms of crystalline and thermal properties, produced under various conditions. These electro-spun mats with different fiber diameters, orientation and mechanical properties can be used for various applications including tissue engineering scaffolds. \ua9 2010 Elsevier Ltd.Peer reviewed: YesNRC publication: Ye