Publications by authors named "Hyeondo Luke Hwang"

2 Publications

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Osmotic Shock-Triggered Assembly of Highly Charged, Nanoparticle-Supported Membranes.

Langmuir 2018 10 22;34(43):13000-13005. Epub 2018 Oct 22.

Spherical nanoparticle-supported lipid bilayers (SSLBs) combine precision nanoparticle engineering with biocompatible interfaces for various applications, ranging from drug delivery platforms to structural probes for membrane proteins. Although the bulk, spontaneous assembly of vesicles and larger silica nanoparticles (>100 nm) robustly yields SSLBs, it will only occur with low charge density vesicles for smaller nanoparticles (<100 nm), a fundamental barrier in increasing SSLB utility and efficacy. Here, through whole mount and cryogenic transmission electron microscopy, we demonstrate that mixing osmotically loaded vesicles with smaller nanoparticles robustly drives the formation of SSLBs with high membrane charge density (up to 60% anionic lipid or 50% cationic lipid). We show that the osmolyte load necessary for SSLB formation is primarily a function of absolute membrane charge density and is not lipid headgroup-dependent, providing a generalizable, tunable approach toward bulk production of highly curved and charged SSLBs with various membrane compositions.
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http://dx.doi.org/10.1021/acs.langmuir.8b03026DOI Listing
October 2018

Quantitative analysis of total reflection X-ray fluorescence from finely layered structures using XeRay.

Rev Sci Instrum 2017 Mar;88(3):033112

James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.

Total reflection x-ray fluorescence (TXRF) is a widely applicable experimental technique for studying chemical element distributions across finely layered structures at extremely high sensitivity. To promote and facilitate scientific discovery using TXRF, we developed a MATLAB-based software package with a graphical user interface, named XeRay, for quick, accurate, and intuitive data analysis. XeRay lets the user model any layered system, each layer with its independent chemical composition and thickness, and enables fine-tuned data fitting. The accuracy of XeRay has been tested in the analysis of TXRF data from both air/liquid interface and liquid/liquid interfacial studies and has been compared to literature results. In an air/liquid interface study, Ca sequestration was measured at a Langmuir monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidic acid (SOPA) on a buffer solution of 1 mM CaCl at pH 7.5. Data analysis with XeRay reveals that each 1 nm of interfacial area contains 2.38 ± 0.06 Ca ions, which corresponds to a 1:1 ratio between SOPA headgroups and Ca ions, consistent with several earlier reports. For the liquid/liquid interface study of Sr enrichment at the dodecane/surfactant/water interface, analysis using XeRay gives a surface enrichment of Sr at 68 Å per ion, consistent with the result published for the same dataset.
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http://dx.doi.org/10.1063/1.4978654DOI Listing
March 2017