ARISE fellow Nihit Saigal is developing a cryogenic super-resolution microscope that will help advance cell biology research at EMBL

Some of science’s biggest mysteries unfold at the smallest scales. Since the invention of the microscope in the 17th century, which enabled pioneers such as Robert Hooke and Antonie van Leeuwenhoek to observe the first cells and microorganisms, it has undergone significant improvements. Today, we can observe structures at the nanometer scale; for instance, using an electron microscope, or visualise specific fluorophore-labelled structures inside a cell through fluorescence microscopy. Moreover, Cryogenic sample preservation techniques have enabled scientists to avoid artifacts introduced by chemical fixation methods, resulting in enhanced image resolution. By bringing these technologies together with the help of a cryo-super-resolution microscope, researchers can obtain some of the most detailed snapshots of the molecular structure of cells.

At the group of Timo Zimmerman at EMBL Heidelberg, ARISE fellow Nihit Saigal is joining efforts with an interdisciplinary group of scientists comprising physicists, engineers, chemists, and computational biologists to develop a new cryogenic super-resolution microscope that will propel new scientific discoveries at EMBL. 

Tell us about your scientific background and what attracted you to the ARISE programme?

I am a condensed matter physicist by training. Before joining EMBL, I studied the fundamental physics of semiconductors. During my PhD and postdoctoral research, I investigated the behaviour of electrons in thin semiconducting materials, analogues of graphene, and developed instrumentation for optics and cryogenics to examine their physical properties. 

After my postdoctoral work, I learned about the ARISE programme from my wife, who works in the Communications Team at EMBL. Immediately, I felt attracted to the well-structured programme and the opportunities for secondments in different sectors. It provided a comprehensive opportunity for me to work at the forefront of life science research and development, while also building the networks and collaborations necessary for my future career. I subsequently searched for groups where I could apply my skills in optics and cryogenics instrumentation, and was fortunate to find an open position in Timo Zimmermann’s group. Timo was very open and interested in discussing the ARISE proposal, offering valuable support and input during the proposal writing process. 

What is your ARISE project about?

My ARISE project focuses on exploring new methods and technologies for cryogenic super-resolution microscopy. In collaboration with the groups of Julia Mahamid, Jonas Ries, and Anna Kreshuk, I am developing a cryogenic single-molecule localisation microscope (cryo-SMLM). This microscope is based on the designs and developments of a microscope at the HHMI Janelia Research Campus in the USA. It will be used for imaging vitrified cells directly on electron microscopy grids and will be integrated into a workflow for cryo-correlative light and electron microscopy (cryo-CLEM).

What are the main features of the cryo-SMLM microscope, and what advantages does cryogenic super-resolution microscopy technology offer for life science research?

Some of the main features of the microscope are:

Super-resolution imaging: The microscope will allow super-resolution imaging of vitrified cells directly on electron microscopy grids. 

High vacuum and cryogenic conditions: The microscope will operate under high vacuum (10^-6 mbar) and cryogenic temperatures. This will prevent ice contamination and devitrification issues during sample transfer and imaging, allowing for longer imaging times due to the requirement of low excitation powers to avoid devitrification. 

Mechanical and thermal stability: We have built a stage to fix the cryostat firmly to the optical table. In this design, the sample is fixed while the objective is used for scanning the field of view. This setup will provide high mechanical and thermal stability during long imaging times. 

Integration with cryo-CLEM: The microscope can be integrated into a workflow for cryo-CLEM. This powerful technique combines molecular labelling from fluorescence light microscopy with high-resolution structural information from electron microscopy, allowing researchers to identify rare and transient structures within cells and capture them in their most native state. 

Ultimately, our cryo-super-resolution microscope aims to bridge the resolution gap between light and electron microscopy, bringing us closer to visualising molecular organisation in cells with greater precision.

Coming from a physics background, what new skills or experiences have you gained so far? 

As an ARISE fellow, I have gained significant new experience and acquired valuable skills. This fellowship has exposed me to recent developments in biological sciences through seminars, conferences, and meetings at EMBL. Additionally, I have participated in various biology and bioimaging courses, where I learned about the potential applications of the microscope I am developing. ARISE has also enabled me to engage with the IndiaBioimaging (IBI) community, which includes bio-imaging scientists and facility managers across India.

In terms of scientific skills, as mentioned, I have a background in semiconductor spectroscopy. At EMBL, I am learning super-resolution imaging techniques. Over the past year and a half, I have learned about the various approaches and implementations of super-resolution microscopy applied to different biological systems, as well as the molecular information that has become available as a result. I have come to appreciate the interdisciplinary nature of this field and the importance of expertise from different scientific disciplines. Furthermore, I recognise the strength of correlative light and electron microscopy, which motivates me to continue developing the microscope.

How do you see your work evolving over the next few years?

Within my ARISE project, and following my experience in cryogenic super-resolution microscopy, I will further explore cryogenic super-resolution imaging techniques and point-scanning-based super-resolution microscopy approaches that utilise dark-state transitions of fluorophores at cryogenic temperatures.

In the future, I would like to combine my previous knowledge and experience in condensed matter physics research with the experience I acquired as part of the ARISE fellowship to continue as an independent researcher. I would like to work with an interdisciplinary research team and also integrate the technology development and service provision aspect of ARISE into my work. 

What interests or hobbies do you enjoy outside of work?

Outside of work, I enjoy running, hiking, playing table tennis, tennis, and cricket, as well as other sports. I also like travelling and listening to Hindi songs.