Matrices trehalose

Figure9.6 Typical luminescenceintensityversustimetrajectories of a single CdTe QD (4.6 nm) embedded in a PVA (a) and a trehalose (b) matrix dispersed on a cover glass surface at room temperature. The excitation intensity was 1.7 kW cm and the integration time was 200 ms bin ...

Figure 9.8 Log vs. log plots of off (a) and on (b) probability distribution compiled from a set of CdTe QDs in a trehalose matrix at room temperature.

Levenson, M. D., and Eesley, G. L. 1979. Polarization selective optical heterodyne detection for dramatically improved sensitivity in laser spectroscopy. Appl. Phys. 19 1-17. Librizzi, R, Viapianni, C., Abbruzzetti, S., and Cordone, L. 2002. Residual water modulates the dynamics of the protein and of the external matrix in trehalose-coated MbCO An infrared and flash-photolysis study. J. Chem. Phys. 116 1193-1200. 

As shown in Table 12.3, dry trehalose vitrifies at a higher temperature than do other disaccharides and the resultant glassy matrix is highly stable in the sense that enthalpy relaxation occurs with more difficulty than in other... 

Three amorphous food model systems consisting of lactose, trehalose, and lactose/trehalose (1 1) as matrix materials, and L-lysine and D-xylose (1 1, 5% w/w) as reactants were prepared by freeze-drying. Aliquots (1 g) of the powdered freeze-dried model materials were transferred into 20-ml glass vials, which were stored in desiccators over four relative vapor pressures (RVP) of 33.2,44.1,54.5, and 65.6%. Triplicate samples were removed at 10- to 24-h intervals depending on the RVP, and the extent of browning was determined spectrophotometrically at 280 and 420 nm. 

The NEB extent in the trehalose model is highest at 33.2 and 44.1% RVP probably because of local heterogeneities. In fact, during preparation of the freeze-dried samples in Petri dishes, we found that the trehalose model showed different extents of browning between the top and bottom of the sample. Of course, the uptake of water at 33.2 and 44.1% RVP environments enhanced the NEB reaction. NEB was observed at a temperature lower than the glass-transition temperature in the present study, which might be related to the heterogeneities and porosity of the matrix structure. 

Moreover, most researchers agree that protection by compounds such as lactose and trehalose depends on the formation of an amorphous phase with the protein [15], The proteins are mechanically immobilized in the glassy, solid matrix during dehydration. The restriction of translational and relaxation processes is thought to prevent protein unfolding, and spatial separation between the protein molecules (i.e dilution of protein molecules within the glassy matrix) is proposed to prevent aggregation [12],... 

S. Perry and N. Winogard, High-iesolution TOF-SIMS imaging of eukaryotic cells preserved in a trehalose matrix. Anal Chem. 77, 7950-7957 (2005). 

Figure 11.7 Inactivation constant during storage of L. paracaei ssp. paracasei as a function of (T-T ) with trehalose as drying matrix. Right-side of the solid line, the matrix is in the rubbery state left-side of the solid line, the matrix is in the glassy state.

The NMR method was used to determine the evolution of the amorphous fraction in a trehalose powder, during a milling procedure which ultimately leads to a fully amorphous state. The purpose of the study was to determine quantitatively the amorphous fraction in crystalline-amorphous powder mixtures of trehalose, in order to assess the ability of the C NMR technique for quantitative amorphous characterisation. Poly(ethylene oxide) (PEO) was tested as a polymer matrix for solid dispersion to enhance drug bioavailability. Solid-state NMR, X-ray diffraction, and transmission electron microscopy were utilised to characterise the high miscibility between PEO and ketoprofen, a model for crystalline drugs with poor water solubility. ... 

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