Biology subjects

Nofal, M.

Publications and source records attributed to Nofal, M..

3 recordsLinked to original sources

bioRxiv2026

High-plex protein imaging across thick tissue by synchronized amplification

High-plex protein imaging is essential for decoding complex tissue organization, yet it remains largely confined to thin sections. Current approaches in millimeter-thick samples suffer from poor signal penetration and depth-dependent, uneven signal amplification. Even with specialized instrumentation to facilitate probe diffusion, iterative millimeter-thick tissue workflows can take more than four days per staining round, and reported eleven-marker experiments extend beyond a month. We introduce Amplification by Cyclic Extension (ACE), a DNA-barcoded, synchronized in situ amplification strategy that uses thermally controlled cyclic extension to coordinate DNA concatemer growth across tissue depths. By synchronously activating and coordinating reaction progression throughout the sample, ACE enables controlled, uniform signal amplification across tissue depths. Using ACE, we demonstrate 63-plex protein and RNA imaging in thin sections, 22-plex protein imaging in 200 m mouse brain sections, and 16-plex protein imaging in 1 mm-thick brain tissue encompassing over three million cells. For millimeter-thick tissues, ACE reduces per-round target-switching time from multiple days to less than eight hours, shifting volumetric high-plex protein imaging from months to days. Together, these results establish ACE as a synchronized amplification strategy that enables scalable high-plex protein imaging in thick tissues.

bioengineering↗

bioRxiv2025

U.S. Visa Bureaucracy and Its Burdens Among Early Career Scholars

Foreign-born research scholars on temporary visas are essential to the U.S. scientific workforce and economy, yet they face systemic challenges shaped by restrictive immigration policies. While scholars across disciplines have long analyzed the evolution of U.S. immigration regimes and citizenship privilege, there remains a critical lack of quantitative data on the financial, temporal, and psychological burdens associated with visa bureaucracy. Here we present original survey data from more than 700 international postdoctoral researchers at Harvard Medical School (HMS) and its affiliated institutions, revealing how visa-related burdens directly impact scholars and their research. For example, over 40% of scholars reported spending more than a month in their home countries to renew U.S. visas, with 5% spending more than six months. Scholars from Asia experienced longer delays and higher costs than those from Europe. Seventy-five percent of respondents reported mental health challenges related to visa stress, often feeling trapped at work, with some requiring medication and time off. Our findings underscore the urgent need for targeted institutional support to promote research productivity, equitable opportunity, and mental well-being. As the U.S. repositions itself as a global scientific leader, such reforms will be critical to recruiting and retaining top talent and advancing equity in science.

scientific communication and education↗

bioRxiv2024

Cryosectioning-enabled super-resolution microscopy for studying nuclear architecture at the single protein level

DNA-PAINT enables nanoscale imaging with virtually unlimited multiplexing and molecular counting. Here, we address challenges, such as variable imaging performance and target accessibility, that can limit its broader applicability. Specifically, we enhance its capacity for robust single-protein imaging and molecular counting by optimizing the integration of TIRF microscopy with physical sectioning, in particular, Tokuyasu cryosectioning. Our method, tomographic & kinetically enhanced DNA-PAINT (tkPAINT), achieves 3 nm localization precision across diverse samples, enhanced imager binding, and improved cellular integrity. tkPAINT can facilitate molecular counting with DNA-PAINT inside the nucleus, as demonstrated through its quantification of the in situ abundance of RNA Polymerase II in both HeLa cells as well as mouse tissues. Anticipating that tkPAINT could become a versatile tool for the exploration of biomolecular organization and interactions across cells and tissues, we also demonstrate its capacity to support multiplexing, multimodal targeting of proteins and nucleic acids, and 3D imaging.

cell biology↗