Sulforhodamine 101 is a synthetic fluorescent compound widely used in various scientific fields. Its ability to emit light after absorbing it makes it a valuable tool for researchers. This dye has advanced our understanding of biological systems and structures that are otherwise invisible.
As a marker, it allows scientists to observe and track processes at a microscopic level. Its application contributes to discoveries in areas ranging from cellular dynamics to complex neural networks. This compound’s properties enable precise visualization, which is fundamental to many modern scientific investigations.
What is Sulforhodamine 101?
Sulforhodamine 101 is a synthetic fluorescent dye, classified as a rhodamine derivative, with a chemical formula of C31H30N2O7S2 and a molar mass of 606.71 g/mol. It appears as a green to dark green crystalline powder. The compound is known for its strong red fluorescence, extending furthest into the red region of the spectrum.
Fluorescence is a phenomenon where certain materials absorb light at one wavelength and then re-emit it at a longer, lower-energy wavelength. Sulforhodamine 101 absorbs light with an excitation peak around 578 nanometers (nm) and emits light with an emission peak around 593 nm. This process allows scientists to visualize structures or processes not visible under normal light, making them “glow” under specific illumination. The compound exhibits high fluorescence quantum yield, meaning it efficiently converts absorbed light into emitted light, contributing to a bright signal. It also demonstrates photostability, resisting fading when exposed to light, which is beneficial for prolonged imaging experiments.
Its Role in Scientific Discovery
Sulforhodamine 101 is widely used as a fluorescent tracer, allowing visualization of structures and processes that would otherwise remain hidden. Its fluorescent properties make it suitable for various microscopy techniques, providing a clear visual signal within complex biological environments. The compound’s red emission is advantageous for imaging, as red light penetrates tissues more effectively than shorter wavelengths, leading to better signal detection in biological samples.
In cell biology, Sulforhodamine 101 is employed for general cell imaging, enabling the visualization of cellular morphology and tracking various cellular processes. For instance, it can be used to monitor regulated exocytosis, a process where cells release molecules, by acting as an activity-dependent probe. Observing the dye’s movement and distribution within cells provides insights into cellular functions and interactions.
The compound has significant application in neuroscience for neuronal tracing and visualizing brain structures. It is utilized as a specific marker for astrocytes, a type of glial cell in the brain, allowing differentiation from neurons in neurophysiological experiments involving calcium imaging methods. This counterstaining capability helps scientists analyze neuronal data separately, contributing to a more precise understanding of brain activity.
Beyond astrocytes, Sulforhodamine 101 also labels myelinating oligodendrocytes, another type of glial cell involved in forming the myelin sheath around nerve fibers. The dye’s ability to highlight these distinct cell types aids in mapping neural circuits and studying their organization within living tissues. Its use in visualizing brain structures provides a clearer picture of the complex architecture of the nervous system.
Its derivative, Texas Red, is widely used for conjugating to various functional groups, particularly primary amines, allowing researchers to label specific proteins or other biomolecules for visualization. This conjugation capability expands its utility, enabling targeted labeling within cells and tissues.
The dye’s utility extends to advanced microscopy techniques, such as confocal and two-photon microscopy, benefiting from its photostability and high quantum yield for deep tissue imaging. These techniques allow for the creation of high-resolution, three-dimensional images of biological samples, revealing intricate details of cellular and tissue organization. Its distinct red emission minimizes spectral overlap with other commonly used green or blue fluorescent dyes, allowing for multi-color imaging experiments.
Important Considerations
Handling Sulforhodamine 101 requires adherence to general safety guidelines. It is stored at temperatures below -15 °C and protected from light to maintain its stability. Minimizing light exposure helps preserve its fluorescent properties over time.
The compound should be stored desiccated to prevent moisture absorption, which can affect its stability. For preparation, a stock solution can be made by dissolving the powder in solvents like DMSO or water at a concentration of 1 millimolar (mM). These stock solutions should be divided into single-use aliquots and stored frozen to avoid repeated freeze-thaw cycles, which can degrade the compound.
Working solutions, diluted from the stock, can be prepared in phosphate or Tris buffer at a pH range of 7-8, depending on experimental needs. While Sulforhodamine 101 is a valuable research tool, some studies suggest it may affect the excitability of neurons, indicating caution in certain neurophysiological experiments.