Probing Early Development using Quantum Sensors

Genes are small sections of DNA that provide a blueprint for making specific proteins. These are inherited from our parents and govern how our cells grow and function. However, genes operate within the environment of a cell, influenced by variables such as temperature, viscosity, and stiffness. Knowing how these factors affect cell division and modify the developmental pathway is still a key question in biology. With our environment changing rapidly, this research will further our understanding of how increasing temperatures and ocean acidity might affect the growth and development of all living organisms.

C. Elegans

C. Elegans are tiny transparent worms about 1mm in length and are an ideal system to study. Their transparency allows for easy observation of their internal features under a microscope, and their fully mapped genetic code means we can identify and study specific genes. Additionally, their short reproductive cycle means we can rapidly analyse all points of their development.

Quantum Nanodiamonds

Our project aims to delve into the internal structure of these worms, focusing on how mechanical properties are affected by temperature variations inside the cells. To achieve this, we need sensors capable of measuring at very small length scales. We utilize quantum nanodiamonds, miniature diamonds approximately 1/1000th the width of a human hair. These diamonds, with small defects in their carbon lattice, enable precise measurements of temperature and viscoelasticity. 

Viscoelasticity is a property of a material related to how it moves with the input of a force. An example of a viscoelastic material is memory foam, as you put weight on it, it deforms (viscous), but it gradually returns to its original shape (elastic). We can measure this in the cells by tracking the movement of the nanodiamonds within it, and the way they move will tell us about the surrounding environment. Because of the small size of the diamonds, this can be measured with very high precision.

Temperature Sensing

Equipped with a custom-built microscope, we illuminate the nanodiamonds with laser light. This excites the electrons in the diamond defect, and as they return to their ground state, they release the excess energy in the form of a red photon, a phenomenon known as photoluminescence.
Simultaneously, we apply a microwave field. When the energy of this microwave field matches the energy difference between specific states in the defect, the electrons are driven to the higher energy state. When these electrons are then excited by the green laser, they do not emit red photons upon returning to the ground state. Consequently, at this microwave frequency, there is a noticeable drop in photoluminescence.

This energy difference between the states is temperature dependent. By identifying the microwave frequency that causes a reduction in photoluminescence, we can determine the energy gap and thus measure the temperature of the nanodiamond.

Experiments

Our experiments will involve injecting the worms with the nanodiamonds into a part of the reproductive tract, meaning that the diamonds will eventually become embedded into the embryos. Then we will look at the embryos using the quantum microscope and track the nanodiamonds as they move through the cell, as well as performing the temperature sensing. This will allow very precise measurements of the temperature and viscoelasticity inside the cells. We will monitor the embryonic development of the C. Elegans and investigate various factors influencing it, including heating, chemical disruptions, and genetic mutations.

Katharine Ninham

NanoDTC PhD Student, c2023