Quantification of propidium iodide delivery with millisecond electric pulses: A model study

A model study of propidium iodide delivery with millisecond electric pulses is presented; this work is a companion of the experimental efforts by Sadik et al. [1]. Both membrane permeabilization and delivery are examined with respect to six extra-cellular conductivities. The transmembrane potential of the permeabilized regions exhibits a consistent value, which corresponds to a bifurcation point in the pore-radius-potential relation. Both the pore area density and membrane conductance increase with an increasing extra-cellular conductivity. On the other hand, the inverse correlation between propidium iodide delivery and extra-cellular conductivity as observed in the experiments is quantitatively captured by the model. This agreement confirms that this behavior is primarily mediated by electrophoretic transport during the pulse. The results suggest that electrophoresis is important even for the delivery of small molecules such as propidium iodide. The direct comparison between model prediction and experimental data presented in this work helps validate the former as a robust predictive tool for the study of electroporation

Ralaxation of deformed drops, vesicles, and cells

The deformation of drops, vesicles, and cells constitutes an important class of problems in chemical and biomedical engineering and is often explored as a means to study interfacial dynamics and mechanical properties of the lipid membrane. Less attention has been paid to the relaxation process after the deforming mechanism is removed. In this study, analyses of such process are presented. A drop, vesicle, or cell of spherical shape at rest is initially deformed into a spheroid. The relaxation process is then solved within the same theoretical framework in both small- and moderate-deformation limits. Different regimes are discovered. For sufficiently small initial deformations, the change in the membrane tension is a negligible higher-order effect for both vesicles and cells, and they behave identically to drops in the relaxation process. For moderate initial deformations, vesicle and cell relaxation is dominantly governed by the folding of undulations on the lipid membrane which differs from the behavior of a drop. Membrane properties, namely, membrane tension and bending rigidity, are the key parameters governing this dynamic process. A detailed comparison with experimental data for vesicles/cells is performed, and the results are presented and discussed

Effect of Shikonin Against Candida albicans Biofilms

Candidiasis is often associated with the formation of biofilms. Candida albicans biofilms are inherently resistant to many clinical antifungal agents and have increasingly been found to be the sources of C. albicans infections. Novel antifungal agents against C. albicans biofilms are urgently needed. The aim of this study was to investigate the effect of shikonin (SK) against C. albicans biofilms and to clarify the underlying mechanisms. XTT reduction assay showed that SK could not only inhibit the formation of biofilms but also destroy the maintenance of mature biofilms. In a mouse vulvovaginal candidiasis (VVC) model, the fungal burden was remarkably reduced upon SK treatment. Further study showed that SK could inhibit hyphae formation and reduce cellular surface hydrophobicity (CSH). Real-time reverse transcription-PCR analysis revealed that several hypha- and adhesion-specific genes were differentially expressed in SK-treated biofilm, including the downregulation of ECE1, HWP1, EFG1, CPH1, RAS1, ALS1, ALS3, CSH1 and upregulation of TUP1, NRG1, BCR1. Moreover, SK induced the production of farnesol, a quorum sensing molecule, and exogenous addition of farnesol enhanced the antibiofilm activity of SK. Taken together, these results indicated that SK could be a favorable antifungal agent in the clinical management of C. albicans biofilms

Plasmonic Metasurfaces with High UVâ Vis Transmittance for Photopatterning of Designer Molecular Orientations

Recent developments of utilizing plasmonic metasurfaces in photopatterning of designer molecular orientations have facilitated numerous new applications of liquid crystals; while the optical efficiency of the metamasks remains a critical issue, especially in the UV region. Here a new design of plasmonic metasurfaces made of parallelepiped arrays is presented which yield very high and broadband transmission in the UVâ vis wavelength range. It is shown that this plasmonic metamask exhibits two polarization peaks originated from a cavity mode and lattice resonance respectively and demonstrated that complex designer molecular orientations can be photopatterned by using this metamask with significantly reduced exposure time. This type of highâ efficiency broadband plasmonic metasurfaces is not only important for high resolution photopatterning of molecular orientation but also tailorable for various other flat optics applications in the UV and near UV regions.Spatially variant molecular orientations are central to many liquid crystal applications. Here a new design of plasmonic metasurfaces with ultrahigh optical transmissions as metamasks for photopatterning arbitrary designer molecular orientations is presented and it is demonstrated that such metamasks can significantly reduce the exposure time of the photopatterning.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149547/1/adom201900117-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149547/2/adom201900117.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149547/3/adom201900117_am.pd