Exciting developments in high-resolution fluorescence microscopy offer researchers a breakthrough – the availability of biocompatible molecular rulers designed for calibrating the latest super-resolution microscopy methods.
Super-resolution microscopy techniques have recently achieved optical resolutions in the nanometer range, corresponding to the size of cellular molecules. However, assessing the achieved resolution on cellular structures like multiprotein complexes proved challenging due to the absence of biomolecular reference systems labeled with dyes at precisely defined positions just a few nanometers apart.
Addressing this gap, a team led by Dr. Gerti Beliu and Professor Markus Sauer from the Rudolf Virchow Center at Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany, has introduced a significant advancement. Published in Advanced Materials, their innovative contribution comes in the form of biocompatible molecular rulers known as PicoRulers (Protein-based Imaging Calibration Optical Rulers).
Utilizing genetic code expansion and click chemistry, the team has engineered these tailor-made molecular rulers, offering precise biomolecular reference structures for fluorescence microscopy applications. This development marks a pivotal step in enhancing the accuracy and reliability of super-resolution microscopy methods for researchers in various fields.
Precision at molecular level
The foundation of PicoRulers lies in the intricate structure of the three-part protein PCNA (Proliferating Cell Nuclear Antigen), a key player in DNA replication and repair. Through meticulous modification involving the introduction of unnatural amino acids at precise locations, this protein undergoes alterations that allow fluorescent dyes or other molecules to be selectively attached with minimal linkage error.
This breakthrough empowers researchers to scrutinize the resolution capabilities of cutting-edge super-resolution microscopy methods with unparalleled accuracy on a specifically defined cellular biomolecule.
Markus Sauer emphasizes, “Achieving the capability to discern authentic biological structures at a sub-10-nanometer level heralds a new era in biological imaging. In comparison to previously utilized artificial macromolecules, our PicoRulers not only boast biological compatibility but also offer unmatched precision for assessing resolution under realistic conditions.”
Opening the door to investigate complex processes in cells
The impact of this technology transcends conventional microscopy boundaries. Gerti Beliu underscores, “Our PicoRulers serve not only as a tool for heightened precision in measurements but also usher in a realm of deeper and more intricate exploration into the complex processes occurring within our cells.”
The ongoing evolution of PicoRulers holds the potential to revolutionize biological and medical imaging, offering molecular-level resolution in the long run. Unprecedentedly, they enable the validation and enhancement of the resolution capabilities of emerging super-resolution microscopy methods on biological samples. This positions them as a valuable asset for unraveling the future intricacies of molecular organization and biomolecular interactions within cells.