# Tools to probe the biophysical properties of cells

> **NIH NIH R01** · NEW YORK UNIVERSITY SCHOOL OF MEDICINE · 2021 · $508,500

## Abstract

Abstract
The physical properties of the cell interior are crucial for the organization and efficiency of biochemical reactions.
The biophysical properties of cells can change during development, cancer progression and aging. Thus, it is
crucial to understand the mechanisms that control the physical properties of the cell and the physiological
consequences of perturbations to this unique environment. The current gold-standard method to study properties
of the cell interior is the microinjection of inorganic nanoparticles. This technique dilutes the cytoplasm, damages
the membrane and cortex, and is highly prone to experimental error. Microinjection is impossible in key genetic
systems such as S. cerevisiae and has been mostly limited to cell culture models due to the difficulty of applying
current techniques to animals. Studies of organelles have been almost impossible, limiting our current
understanding to the cytoplasm. Finally, microinjection is labor intensive, making it impossible to undertake large-
scale genetic screens to find genes and pathways that control the properties of the cell interior.
 We have created self-assembling, genetically-encoded fluorescent probes (GEMs) with 20- and 40-nm
diameters that overcome all of the problems of the previous state-of-the-art technologies. After inserting the gene
encoding GEMs, cells have nanoparticles permanently present, thus no microinjection is required. GEMs
massively increase the speed, efficiency and reproducibility of microrheology experiments. Our recent discovery
of pathways that control the physical properties of the cytoplasm required hundreds of experiments in an
extensive genetic screen, which would not have been feasible without GEMs. We will use this focused technology
research funding to extend the GEM technology and make it accessible to a broad community of scientists. In
Aim 1, we will target GEMs to the nucleus and mitochondria, to characterize these organelles for the first time.
In Aim 2, we will generate nanoparticles from 50 nm to 100 nm in size. The cellular environment varies
substantially for objects of different sizes, just as car and a bicycle experience a traffic jam differently. Thus, we
must investigate the environment for a wide range of particle sizes. Finally, in Aim 3, we will extend GEM
technology to animals with well-defined developmental patterns to enable characterization of the physical
properties of cells within tissues throughout development. Throughout, we will develop computational tools to
identify and track GEMs, compare our technology to current gold-standard techniques and generate reference
datasets that will aid the community in future studies. Overall, we will develop a suite of easy-to-use nanoparticles
that will accelerate the discovery of mechanisms that control the physical properties of animals, cells and
organelles. This will help elucidate the role of the intracellular environment to cell function, and the contributions
of the loss of thi...

## Key facts

- **NIH application ID:** 10136638
- **Project number:** 5R01GM132447-03
- **Recipient organization:** NEW YORK UNIVERSITY SCHOOL OF MEDICINE
- **Principal Investigator:** Liam J Holt
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $508,500
- **Award type:** 5
- **Project period:** 2019-07-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10136638

## Citation

> US National Institutes of Health, RePORTER application 10136638, Tools to probe the biophysical properties of cells (5R01GM132447-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10136638. Licensed CC0.

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