Quenched Stochastic Optical Reconstruction Microscopy (qSTORM) with Graphene Oxide

Ruiheng Li,Henry Cox,Ian S Roberts,Thomas A Waigh,Jian R Lu,Pantelis Georgiades,Sorasak Phanphak

doi:10.1038/s41598-018-35297-4

Ruiheng Li, Henry Cox + Show 5 more

Open Access

https://doi.org/10.1038/s41598-018-35297-4

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Abstract

Quenched Stochastic Optical Reconstruction Microscopy (qSTORM) was demonstrated with graphene oxide sheets, peptides and bacteria; a method of contrast enhancement with super-resolution fluorescence microscopy. Individual sheets of graphene oxide (GO) were imaged with a resolution of 16 nm using the quenching of fluorescence emission by GO via its large Resonant Energy Transfer (RET) efficiency. The method was then extended to image self-assembled peptide aggregates (resolution 19 nm) and live bacterial cells (resolution 55 nm, the capsular structure of E. coli from urinary tract infections) with extremely low backgrounds and high contrasts (between one and two orders of magnitude contrast factor improvements that depended on the thickness of the graphene oxide layer used). Graphene oxide films combined with STORM imaging thus provide an extremely convenient method to image samples with large backgrounds due to non-specifically bound fluorophores (either due to excess labelling or autofluorescent molecules), which is a common occurrence in studies of both biological cells and soft-condensed matter. The GO quenches the fluorescence across a thin layer at distances of less than 15 nm. Graphene oxide films coated with thin layers (≤15 nm) of polystyrene, polymethylmethacrylate and polylysine are shown to be effective in producing high contrast qSTORM images, providing a convenient modulation of sample/substrate interactions. The GO coatings can also provide an increased image resolution and a factor of 2.3 improvement was observed with the peptide fibres using a feature of interest metric,when there was a large non-specifically bound background.

Highlights

Conventional quenched fluorescence microscopy has previously been demonstrated with the imaging of individual graphene oxide (GO) sheets, as a high throughput method to characterise their morphology[7]
The rough edges of graphene oxide sheets were imaged with a resolution of 16 nm; a two orders of magnitude improvement on previous diffraction limited fluorescence microscopy methods[7]
The distance dependence of graphene oxide quenching of fluorophores was studied in the range 2–15 nm and it is believed to be due to the non-radiative resonance energy transfer between graphene oxide sheets and the fluorescent dyes i.e. Resonant Energy Transfer (RET)

Summary

Introduction

Conventional quenched fluorescence microscopy has previously been demonstrated with the imaging of individual graphene oxide (GO) sheets, as a high throughput method to characterise their morphology[7]. A sample of self-assembled I3K peptide fibrils was used to demonstrate the quenching effect of sparse single layer graphene oxide sheets.

Results

Conclusion