Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 May 15;146(19):12877-12882.
doi: 10.1021/jacs.4c00611. Epub 2024 May 6.

Single-Molecule Stoichiometry of Supramolecular Complexes

Alan McLean  1 , Renata L Sala  1 , Brooke W Longbottom  1 , Alexander R Carr  1 , Jade A McCune  1 , Steven F Lee  2 , Oren A Scherman  1
Affiliations

Single-Molecule Stoichiometry of Supramolecular Complexes

Alan McLean et al. J Am Chem Soc. .

Abstract

The use of single-molecule microscopy is introduced as a method to quantify the photophysical properties of supramolecular complexes rapidly at ultra low concentrations (<1 nM), previously inaccessible. Using a model supramolecular system based on the host-guest complexation of cucurbit[n]uril (CB[n]) macrocycles together with a fluorescent guest (Ant910Me), we probe fluorescent CB[n] host-guest complexes in the single molecule regime. We show quantification and differentiation of host-guest photophysics and stoichiometries, both in aqueous media and noninvasively in hydrogel, by thresholding detected photons. This methodology has wide reaching implications in aiding the design of next-generation materials with programmed and controlled properties.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
A. Schematic and chemical structures of cucurbit[n]uril (CB[n]) where n = 7 and 8 and the Ant910Me guest molecule (2 Cl– counterions not shown). Host–guest binding occurs between Ant910Me and CB[7] (1:2) and CB[8] (2:2). B. Time resolution and concentration limits for various techniques used to study noncovalent interactions, including single-molecule microscopy (SMM), bulk optical measurements (BOM), isothermal titration calorimetry (ITC), and NMR spectroscopy. C. Absorption/emission from free Ant910Me and host–guest complexes of Ant910Me with CB[7] and CB[8]. D. Overview of SMM acquisition, where each molecule emits fluorescence (“on state”) until deactivated (“off state”), scale bar is 5 μm (stack) and 2 pixels in length (174 nm, localization) E. SMM processing pipeline, scale bars equal 2 pixels (174 nm).
Figure 2
Figure 2
A. SMM localizations for Ant910Me and 2Ant910Me·2CB[8] in aqueous solution at ultra low concentration (300 pM - 1 nM see Methods; scale bar is 5 μm and 2 pixels (174 nm) for inset images). B. Photon histograms where the x-axis is intensity (photons) and the y-axis is the frequency (in %) of the bin. The star (*) above the final bin indicates that the bin includes all values greater than. Median photons detected is provided in the upper right. The thresholded value (dashed line) was set to the 90th percentile of the Ant910Me free dye histogram (at 9526 detected photons). C. Thresholded localizations for Ant910Me and 2Ant910Me·2CB[8] in aqueous solution, scale bar is 5 μm and 2 pixels (174 nm) for inset images.
Figure 3
Figure 3
A. Depiction of Ant910Me·2CB[7], and 2Ant910Me·2CB[8] in agarose hydrogel and associated photon histograms in 3 wt% agarose solution. The thresholded value (dashed line) was set to the 90th percentile of the Ant910Me·2CB[7] agarose histogram at 9786 detected photons. B. Thresholded localizations for agarose samples (Ant910Me·2CB[7] and 2Ant910Me·2CB[8] respectively), scale bar is 5 μm and 2 pixels (174 nm) for inset images.
See this image and copyright information in PMC

References

    1. Behrend R.; Meyer E.; Rusche F. I. Ueber condensationsproducte aus glycoluril und formaldehyd. Justus Liebigs Ann. Chem. 1905, 339, 1–37. 10.1002/jlac.19053390102. - DOI
    1. Meyer E.Uber die condensation des harnstoffs mit glyoxal und des glykolurils mit formaldehyd. Heidelberg. Ph.D. thesis, Heidelberg University, Heidelberg, 1904.
    1. Kim J.; Jung I.-S.; Kim S.-Y.; Lee E.; Kang J.-K.; Sakamoto S.; Yamaguchi K.; Kim K. New Cucurbituril Homologues: Syntheses, Isolation, Characterization, and X-ray Crystal Structures of Cucurbit[n]uril (n = 5, 7, and 8). J. Am. Chem. Soc. 2000, 122, 540–541. 10.1021/ja993376p. - DOI
    1. Barrow S. J.; Kasera S.; Rowland M. J.; del Barrio J.; Scherman O. A. Cucurbituril-Based Molecular Recognition. Chem. Rev. 2015, 115 (22), 12320–12406. 10.1021/acs.chemrev.5b00341. - DOI - PubMed
    1. Assaf K. I.; Nau W. M. Cucurbiturils: from synthesis to high-affinity binding and catalysis. Chem. Soc. Rev. 2015, 44, 394–418. 10.1039/C4CS00273C. - DOI - PubMed

LinkOut - more resources