Work

Improved Sensitivity in a Modified Berkeley Red Sensor of Transmembrane Potential

Year: 2024

Type: article

Abstract: Voltage imaging is an important complement to traditional methods for probing cellular physiology, like electrode-based patch clamp techniques. Unlike the related Ca2+ imaging, voltage imaging provides a direct visualization of bioelectricity changes. We have been exploring the use of sulfonated silicon rhodamine dyes (Berkeley Red Sensor of Transmembrane potential, or BeRST) for voltage imaging. In this study, we explore the effect of converting BeRST to diEt BeRST, by replacing the dimethyl aniline of BeRST with a diethyl aniline group. The new VF dye, diEt BeRST, has a voltage sensitivity of 40% ΔF/F per 100 mV, a 33% increase compared to the original BeRST dye, which has a sensitivity of 30% ΔF/F per 100 mV. In neurons, the cellular brightness of diEt BeRST is about 20% as bright as BeRST, which may be due to the lower solubility of diEt BeRST (300 μM) compared to BeRST (800 μM). Despite this lower cellular brightness, diEt BeRST is able to record spontaneous and evoked action potentials from multiple neurons, simultaneously, and in single trials. Far-red excitation and emission profiles enable diEt BeRST to be used alongside existing fluorescent indicators of cellular physiology, like Ca2+-sensitive Oregon Green BAPTA (OGB). In hippocampal neurons, simultaneous voltage and Ca2+ imaging reveals neuronal spiking patterns and frequencies that cannot be resolved with traditional Ca2+ imaging methods. This study represents a first step towards describing the structural features that define voltage sensitivity and brightness in silicon rhodamine-based BeRST indicators.

Source: ACS Chemical Biology

DOI: 10.1021/acschembio.4c00442

Authors: Marisol X. Navarro, Nels C. Gerstner, Soren M. Lipman, Gabby E. Dolgonos, Evan W. Miller

Institution: University of California, Berkeley

Language: English

Topic: Advanced Fluorescence Microscopy Techniques

Subfield: Biophysics

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: green

Funders: National Science Foundation, National Institutes of Health, National Institute of General Medical Sciences, National Institute of Neurological Disorders and Stroke

Awards: Acquisition of a Cryoprobe and Related Accessories for a 600 MHz NMR Spectrometer to Support Health Research Activities at the University of California, Berkeley, Design, synthesis and application of long wavelength fluorophores for bioimaging, University of California Berkeley Chemistry-Biology Interface Training Program, Chemical Biology Training Program, Interrogating Neuronal Membrane Potential Dynamics with Optical Voltage Sensors