Stoichiometric quantification of spatially dense assemblies with qPAINT

Area of Science:

• Biophysics
• Nanotechnology
• Molecular Imaging

Background:

• Quantitative PAINT (qPAINT) is a key technique for quantifying molecules in nanoscale structures.
• The impact of molecular proximity and potential cross-reactivity on qPAINT accuracy in dense arrangements remains uncharacterized.

Purpose of the Study:

• To investigate the robustness and accuracy of qPAINT measurements in densely packed molecular assemblies.
• To determine the minimum resolvable distance between target molecules using qPAINT.

Main Methods:

• Utilized qPAINT methodology to analyze molecular arrangements with varying degrees of proximity.
• Employed high-resolution imaging to assess molecular separation and potential cross-reactivity.

Main Results:

• Demonstrated that qPAINT measurements are reliable even when target molecules are separated by as little as 3 nm.
• Established that molecular crowding does not significantly perturb qPAINT quantification within this proximity range.

Conclusions:

• qPAINT is a robust method for accurate molecular counting in nanoscale assemblies, even under conditions of high molecular density.
• The findings support the use of qPAINT for analyzing complex biological structures where molecules are closely packed.