Novel low-molecular-weight-gelator-based microcapsules with controllable morphology and temperature responsiveness.

A new type of microcapsules with controllable morphology is presented. They are based on a low-molecular-weight gelator and can be switched from temperature-stable to temperature-responsive by simply modifying the preparation method.

Straightforward preparation of organic colloidal particles by harnessing spontaneous non-covalent interactions of active molecules from natural origin.

We demonstrate a straightforward method to prepare organic colloidal particles based on the spontaneous molecular interactions between small molecular weight actives of natural origin. Representative reactive natural actives from three of the most researched classes of phytochemicals including berberine (isoquinoline alkaloid), tannic acid (polyphenol) and glycyrrhizin (olenane type saponin) were chosen for the study. Binding parameters (association constant, binding enthalpy and entropy) obtained from isothermal titration calorimetry indicated that berberine strongly interacted with tannic acid to form insoluble colloidal complex which could be stabilised in the presence of glycyrrhizin (due to its interaction with both berberine and tannic acid and also due to its amphiphilic nature). Working on this principle, the mutual interactions of these three natural actives were exploited to obtain stable spherical particles with a mean diameter of less than 100 nm (77 nm) simply by mixing the aqueous solutions of berberine:tannic acid:glycyrrhizin at molar ratio of 2:1:1. The involvement of aromatic chromophore (π-π*) system and charged N atom of berberine in the spontaneous interaction between berberine and tannic acid was confirmed from spectral analysis. X-ray diffraction study suggested formation of amorphous organic colloidal particles, and the spherical shape of colloidal particles was confirmed by transmission electron microscopy.

Quercetin loaded biopolymeric colloidal particles prepared by simultaneous precipitation of quercetin with hydrophobic protein in aqueous medium.

Quercetin loaded biopolymeric colloidal particles were prepared by precipitating quercetin (water insoluble polyphenol) and zein (hydrophobic protein), simultaneously, by adding their hydro-alcoholic solution to aqueous solution in presence of sodium caseinate as an electrosteric stabiliser. The presence of protein resulted in altering the shape of quercetin precipitates from needle-like to spherical shape at higher zein proportions, as confirmed by transmission electron microscopy. The average particle size of zein:quercetin composite particles was below 200 nm (130-161 nm) with negative surface charge (-30 to -41 mV), as confirmed by dynamic light scattering and electrophoretic mobility data. Solid state characterisation (X-ray diffraction) and spectroscopic measurements (UV-Vis and IR spectroscopy) confirmed characteristic changes in quercetin due to the entrapment in the biopolymeric matrix of colloidal particles. Results from anti-oxidant study demonstrated the advantage of entrapping quercetin in the colloidal particles in terms of the chemical stability in the alkaline pH and against photodegradation under UV-light irradiation.

Attenuated total internal reflection infrared microscopy of multilayer plastic packaging foils.

Multilayer plastic foils are important packaging materials that are used to extend the shelf life of food products and drinks. Fourier transform infrared (FT-IR) spectroscopic imaging using attenuated total internal reflection (ATR) can be used for the identification and localization of different layers in multilayer foils. A new type of ATR crystal was used in combination with a linear array detector through which large sample areas (400 x 400 microm(2)) could be imaged with a pixel size of 1.6 microm. The method was tested on laminated plastic packing materials containing 5 to 12 layers. The results of the identification of the different materials using ATR-FT-IR were compared with differential scanning calorimetry (DSC) and the layer thickness of the individual layers measured by ATR-FT-IR was compared with polarized light microscopy (LM) and scanning electron microscopy (SEM). It has been demonstrated that individual layers with a thickness of about 3 microm could be identified in multilayer foils with a total thickness ranging from 100 to 150 microm. The results show a spatial resolution of about 4 microm (measured at wavenumbers ranging from 1000 to 1730 cm(-1)), which is about a factor of two better than can be obtained using transmission FT-IR imaging. An additional advantage of ATR is the ease of sample preparation. A good correspondence was found between visible and FT-IR images. The results of ATR-FT-IR imaging were in agreement with those obtained by LM, SEM, and DSC. ATR-FT-IR is superior to the combination of these techniques because it delivers both spatial and chemical information.

The use of multivariate modelling of near infra-red spectra to predict the butter fat content of spreads.

In order to obtain a rapid method that can detect adulteration of butter fats with cheaper vegetable fats, the use of NIR spectroscopy and multivariate modelling was explored. For model building and validation, an extensive set of samples was collected, consisting of 152 butter samples, 42 oils and 200 blends thereof. Variations in butter fat composition are reflected in distinct NIR spectral regions. Principal components analysis and partial least square discriminant analysis was used to inspect the variation within the sample set. As reference values for training partial least squares models, butter fat levels as declared by suppliers were taken, as well as C4:0 fatty acid levels as measured directly by GC. All samples were used for training, except for 100 blends, which were used later for validation. Different pre-processing and PLS approaches were explored, resulting in models that had a RMSEPs for butter fat and C4:0 fatty acid level in the range of 4.3-8.2 and 0.33-0.38% (w/w), respectively. The performance of NIR in assessment of C4:0 fatty acid levels is lower as for GC, but this disadvantage is outweighed by shorter measurement times and the lower skill levels required. Furthermore NIR is able to assess overall levels of butter fat, in addition to the indirect indicator provided by the C4:0 fatty acid level.