An attenuated live measles virus (MV) was characterized by several biophysical methods as a function of temperature and pH. Following a method developed previously, the resultant light scattering and spectroscopic data were synthesized into an empirical phase diagram that visually and simultaneously represents the entire data set. Using this empirically-based phase diagram, screening assays were developed to identify potential vaccine stabilizers. Various compounds are shown by these assays to inhibit the temperature-induced aggregation of viral particles, and also to protect the integrity of the viral envelope. Accelerated stability assays show that, upon thermal challenge, MV formulated with these excipients retains its infectivity to a significant extent. Thus, the enhanced physical stability produced by this method is shown to protect the biological activity of this important but labile vaccine.

Tick-borne Babesia parasites are responsible for costly diseases worldwide. Improved control and prevention tools are urgently needed, but development of such tools is limited by numerous gaps in knowledge of the parasite-host relationships. We hereby used atomic force microscopy (AFM) and frequency-modulated Kelvin probe potential microscopy (FM-KPFM) techniques to compare size, texture, roughness and surface potential of normal and infected Babesia bovis, B. bigemina and B. caballi erythrocytes to better understand the physical properties of these parasites. In addition, AFM and FM-KPFM allowed a detailed view of extraerythrocytic merozoites revealing shape, topography and surface potential of paired and single parasites. B. bovis-infected erythrocytes display distinct surface texture and overall roughness compared to noninfected erythrocytes. Interestingly, B. caballi-infected erythrocytes do not display the surface ridges typical in B. bovis parasites. Observations of extraerythrocytic B. bovis, B. bigemina and B. caballi merozoites using AFM revealed differences in size and shape between these three parasites. Finally, similar to what was previously observed for Plasmodium-infected erythrocytes, FM-KPFM images reveal an unequal electric charge distribution, with higher surface potential above the erythrocyte regions that are likely associated with Babesia parasites than over its remainder regions. In addition, the surface potential of paired extraerythrocytic B. bovis Mo7 merozoites revealed an asymmetric potential distribution. These observations may be important to better understand the unique cytoadhesive properties of B. bovis-infected erythrocytes, and to speculate on the role of differences in the distribution of surface charges in the biology of the parasites.

The effect of annealing on the phase transformation and the dielectric properties of poly(vinylidene fluoride) (PVDF) is explored using quasi-single molecule (quasi-SM) microscopy. The solvatochromic properties of nile red (NR) are employed to measure the spatial distribution of the local dielectric constant (ε) in ∼30 μm thick PVDF films before and after annealing at 90 °C. The results presented here demonstrate that nonannealed films exhibit much larger ε distributions, both in terms of magnitude and distribution, when compared to annealed films. The polymorphic phase of PVDF before and after annealing is also confirmed using X-ray diffraction. Nonannealed films are found to be in the γ-phase with annealing promoting the transition to primarily β-phase. Combining these results, we conclude that the decrease in ε with annealing time is due to the phase transformation from γ- to β-phase. Using quasi-SM imaging techniques one can readily visualize the ε environments present within different polymorphic phases of PVDF.

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