Honors & Awards

  • Stanford Bio-X SIGF Fellow, Stanford Bio-X (Sep. 2021- Aug. 2024)
  • Morgridge Family SIGF Fellow, Stanford Office of the Vice Provost for Graduate Education (Sep. 2021- Aug. 2024)

Professional Affiliations and Activities

  • Member, Phi Tau Phi (2019 - Present)

Education & Certifications

  • Master of Science, Stanford University, BIOE-MS (2021)
  • MD, National Taiwan University (2019)
  • Certified Physician, Ministry of Health, Taiwan (2019)

All Publications

  • Topological damping in an ultrafast giant cell. Proceedings of the National Academy of Sciences of the United States of America Chang, R., Prakash, M. 2023; 120 (41): e2303940120


    Cellular systems are known to exhibit some of the fastest movements in biology, but little is known as to how single cells can dissipate this energy rapidly and adapt to such large accelerations without disrupting internal architecture. To address this, we investigate Spirostomum ambiguum-a giant cell (1-4 mm in length) well-known to exhibit ultrafast contractions (50% of body length) within 5 ms with a peak acceleration of 15[Formula: see text]. Utilizing transmitted electron microscopy and confocal imaging, we identify an association of rough endoplasmic reticulum (RER) and vacuoles throughout the cell-forming a contiguous fenestrated membrane architecture that topologically entangles these two organelles. A nearly uniform interorganelle spacing of 60 nm is observed between RER and vacuoles, closely packing the entire cell. Inspired by the entangled organelle structure, we study the mechanical properties of entangled deformable particles using a vertex-based model, with all simulation parameters matching 10 dimensionless numbers to ensure dynamic similarity. We demonstrate how entangled deformable particles respond to external loads by an increased viscosity against squeezing and help preserve spatial relationships. Because this enhanced damping arises from the entanglement of two networks incurring a strain-induced jamming transition at subcritical volume fractions, which is demonstrated through the spatial correlation of velocity direction, we term this phenomenon "topological damping." Our findings suggest a mechanical role of RER-vacuolar meshwork as a metamaterial capable of damping an ultrafast contraction event.

    View details for DOI 10.1073/pnas.2303940120

    View details for PubMedID 37792511

  • Energetics of the Microsporidian Polar Tube Invasion Machinery. bioRxiv : the preprint server for biology Chang, R., Davydov, A., Jaroenlak, P., Budaitis, B., Ekiert, D. C., Bhabha, G., Prakash, M. 2023


    Microsporidia are eukaryotic, obligate intracellular parasites that infect a wide range of hosts, leading to health and economic burdens worldwide. Microsporidia use an un-usual invasion organelle called the polar tube (PT), which is ejected from a dormant spore at ultra-fast speeds, to infect host cells. The mechanics of PT ejection are impressive. Anncaliia algerae microsporidia spores (3-4 mu m in size) shoot out a 100-nm-wide PT at a speed of 300 mu m/sec, creating a shear rate of 3000 sec - 1 . The infectious cargo, which contains two nuclei, is shot through this narrow tube for a distance of ~60-140 mu m 1 and into the host cell. Considering the large hydraulic resistance in an extremely thin tube and the low-Reynolds-number nature of the process, it is not known how microsporidia can achieve this ultrafast event. In this study, we use Serial Block-Face Scanning Electron Microscopy to capture 3-dimensional snapshots of A. algerae spores in different states of the PT ejection process. Grounded in these data, we propose a theoretical framework starting with a systematic exploration of possible topological connectivity amongst organelles, and assess the energy requirements of the resulting models. We perform PT firing experiments in media of varying viscosity, and use the results to rank our proposed hypotheses based on their predicted energy requirement, pressure and power. We also present a possible mechanism for cargo translocation, and quantitatively compare our predictions to experimental observations. Our study provides a comprehensive biophysical analysis of the energy dissipation of microsporidian infection process and demonstrates the extreme limits of cellular hydraulics.Statement of Significance: Microsporidia are a group of spore-forming, intracellular parasites that infect a wide range of hosts (including humans). Once triggered, microsporidian spores (3-4 mu m in size) shoot out a specialized organelle called the polar tube (PT) (60-140 mu m long, 100 nm wide) at ultrafast speed (300 mu m/sec), penetrating host cells and acting as a conduit for the transport of infectious cargo. Although this process has fascinated biologists for a century, the biophysical mechanisms underlying PT extrusion are not understood. We thus take a data-driven approach to generate models for the physical basis of PT firing and cargo transport through the PT. Our approach here demonstrates the extreme limits of cellular hydraulics and the potential applications of biophysical approaches to other cellular architectures.

    View details for DOI 10.1101/2023.01.17.524456

    View details for PubMedID 36711805

  • Modified full-face snorkel masks as reusable personal protective equipment for hospital personnel. PloS one Kroo, L., Kothari, A., Hannebelle, M., Herring, G., Pollina, T., Chang, R., Peralta, D., Banavar, S. P., Flaum, E., Soto-Montoya, H., Li, H., Combes, K., Pan, E., Vu, K., Yen, K., Dale, J., Kolbay, P., Ellgas, S., Konte, R., Hajian, R., Zhong, G., Jacobs, N., Jain, A., Kober, F., Ayala, G., Allinne, Q., Cucinelli, N., Kasper, D., Borroni, L., Gerber, P., Venook, R., Baek, P., Arora, N., Wagner, P., Miki, R., Kohn, J., Kohn Bitran, D., Pearson, J., Arias-Arco, B., Larrainzar-Garijo, R., Herrera, C. M., Prakash, M. 2021; 16 (1): e0244422


    Here we adapt and evaluate a full-face snorkel mask for use as personal protective equipment (PPE) for health care workers, who lack appropriate alternatives during the COVID-19 crisis in the spring of 2020. The design (referred to as Pneumask) consists of a custom snorkel-specific adapter that couples the snorkel-port of the mask to a rated filter (either a medical-grade ventilator inline filter or an industrial filter). This design has been tested for the sealing capability of the mask, filter performance, CO2 buildup and clinical usability. These tests found the Pneumask capable of forming a seal that exceeds the standards required for half-face respirators or N95 respirators. Filter testing indicates a range of options with varying performance depending on the quality of filter selected, but with typical filter performance exceeding or comparable to the N95 standard. CO2 buildup was found to be roughly equivalent to levels found in half-face elastomeric respirators in literature. Clinical usability tests indicate sufficient visibility and, while speaking is somewhat muffled, this can be addressed via amplification (Bluetooth voice relay to cell phone speakers through an app) in noisy environments. We present guidance on the assembly, usage (donning and doffing) and decontamination protocols. The benefit of the Pneumask as PPE is that it is reusable for longer periods than typical disposable N95 respirators, as the snorkel mask can withstand rigorous decontamination protocols (that are standard to regular elastomeric respirators). With the dire worldwide shortage of PPE for medical personnel, our conclusions on the performance and efficacy of Pneumask as an N95-alternative technology are cautiously optimistic.

    View details for DOI 10.1371/journal.pone.0244422

    View details for PubMedID 33439902