Biology subjects

Park, W. M.

Publications and source records attributed to Park, W. M..

4 recordsLinked to original sources

bioRxiv2026

Cooperative self-assembly of nanoparticle-encapsulating hybrid protein cages

Protein cages are versatile platforms capable of encapsulating a wide range of nanoparticle cargo within biocompatible protein shells while providing tunable functionalities. Here, we investigated a self-assembly system that forms vesicle-like protein cages while simultaneously encapsulating nanoparticles at high density, yielding pomegranate-like protein- nanoparticle hybrid materials. Amphiphilic recombinant fusion protein building blocks based on elastin-like polypeptides, leucin zippers, and fluorescent proteins were employed to assemble vesicle-like protein cages via temperature-triggered liquid-liquid phase separation in the presence of fluorescent polystyrene nanoparticles. Analysis of nanoparticle encapsulation density and protein cage size indicates cooperative interactions between protein building blocks and nanoparticles that mediate the formation of protein-nanoparticle coacervate intermediates, which subsequently convert into core-shell hybrid protein cages, as further supported by kinetics studies. We demonstrate the self-assembly hybrid protein cages incorporating a fluorescent calcium sensor protein and titanium oxide nanoparticles, which exhibit a drastic enhancement in their calcium-sensing capability as a result of nanoparticle encapsulation. This platform offers a broadly applicable strategy that integrates protein biofunctionality with diverse nanoparticle properties for development of advanced hybrid materials.

biochemistry↗

bioRxiv2024

Self-assembly of microstructured protein coatings with programmable functionality for fluorescent biosensors

Proteins, as genetically programmable functional macromolecules, hold immense potential as biocompatible self-assembling building blocks. Despite their versatility in building coating materials, it has been often hindered from programming their functionality genetically. In this study, we demonstrate a modular self-assembly of protein coatings that are genetically programmable for a biosensor application. We designed recombinant fusion protein building blocks to form microstructured coatings on diverse substrates, such as glass or polymer, through a thermally triggered liquid-liquid phase separation and an orthogonal high-affinity coiled-coil interaction. We incorporated fluorescence proteins into coatings and controlled protein density to enable fluorescence imaging and quantification in a low-resource setting. Then, we created a coating for a calcium biosensor using a genetically engineered calcium indicator protein. This protein coating served as the foundation for our smartphone-based fluorescence biosensor, which successfully measured free calcium concentrations in the millimolar range at which extracellular calcium homeostasis is maintained. Using this fluorescence biosensor, we were able to detect abnormal physiological conditions such as mild or moderate hypercalcemia. We envision that this modular and genetically programmable functional protein coating platform could be extended to the development of highly accessible, low-cost fluorescent biosensors for a variety of targets.

bioengineering↗

bioRxiv2021

Recording of cellular physiological histories along optically readable self-assembling protein chains

Observing cellular physiological histories is key to understanding normal and disease-related processes, but longitudinal imaging is laborious and equipment-intensive. A tantalizing possibility is that cells could record such histories in the form of digital biological information within themselves, for later high-throughput readout. Here we show that this concept can be realized through information storage in the form of growing protein chains made out of multiple self-assembling subunits bearing different labels, each corresponding to a different cellular state or function, so that the physiological history of the cell can be visually read out along the chain of proteins. Conveniently, such protein chains are fully genetically encoded, and easily readable with simple, conventional optical microscopy techniques, compatible with visualization of cellular shape and molecular content. We use such expression recording islands (XRIs) to record gene expression timecourse downstream of pharmacological and physiological stimuli, in cultured neurons and in living mouse brain.

synthetic biology↗

bioRxiv2019

Precision calcium imaging of dense neural populations via a cell body-targeted calcium indicator

Methods for one-photon fluorescent imaging of calcium dynamics in vivo are popular due to their ability to simultaneously capture the dynamics of hundreds of neurons across large fields of view, at a low equipment complexity and cost. In contrast to two-photon methods, however, one-photon methods suffer from higher levels of crosstalk between cell bodies and the surrounding neuropil, resulting in decreased signal-to-noise and artifactual correlations of neural activity. Here, we address this problem by engineering cell body-targeted variants of the fluorescent calcium indicator GCaMP6f. We screened fusions of GCaMP6f to both natural as well as engineered peptides, and identified fusions that localized GCaMP6f to within approximately 50 microns of the cell body of neurons in live mice and larval zebrafish. One-photon imaging of soma-targeted GCaMP6f in dense neural circuits reported fewer artifactual spikes from neuropil, increased signal-to-noise ratio, and decreased artifactual correlation across neurons. Thus, soma-targeting of fluorescent calcium indicators increases neuronal signal fidelity and may facilitate even greater usage of simple, powerful, one-photon methods of population imaging of neural calcium dynamics.

neuroscience↗