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Cerutti E, D'Amico M, Cainero I, Dellino GI, Faretta M, Vicidomini G, Pelicci PG, Bianchini P, Diaspro A, Lanzanò L. Evaluation of sted super-resolution image quality by image correlation spectroscopy (QuICS). Sci Rep 2021; 11:20782. [PMID: 34675304 PMCID: PMC8531054 DOI: 10.1038/s41598-021-00301-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/08/2021] [Indexed: 12/05/2022] Open
Abstract
Quantifying the imaging performances in an unbiased way is of outmost importance in super-resolution microscopy. Here, we describe an algorithm based on image correlation spectroscopy (ICS) that can be used to assess the quality of super-resolution images. The algorithm is based on the calculation of an autocorrelation function and provides three different parameters: the width of the autocorrelation function, related to the spatial resolution; the brightness, related to the image contrast; the relative noise variance, related to the signal-to-noise ratio of the image. We use this algorithm to evaluate the quality of stimulated emission depletion (STED) images of DNA replication foci in U937 cells acquired under different imaging conditions. Increasing the STED depletion power improves the resolution but may reduce the image contrast. Increasing the number of line averages improves the signal-to-noise ratio but facilitates the onset of photobleaching and subsequent reduction of the image contrast. Finally, we evaluate the performances of two different separation of photons by lifetime tuning (SPLIT) approaches: the method of tunable STED depletion power and the commercially available Leica Tau-STED. We find that SPLIT provides an efficient way to improve the resolution and contrast in STED microscopy.
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Affiliation(s)
- Elena Cerutti
- Department of Physics and Astronomy "Ettore Majorana", University of Catania, Via S. Sofia 64, 95123, Catania, Italy.,Nanoscopy and NIC@IIT, CHT Erzelli, Istituto Italiano di Tecnologia, Via Enrico Melen 83, Building B, 16152, Genoa, Italy
| | - Morgana D'Amico
- Department of Physics and Astronomy "Ettore Majorana", University of Catania, Via S. Sofia 64, 95123, Catania, Italy
| | - Isotta Cainero
- Nanoscopy and NIC@IIT, CHT Erzelli, Istituto Italiano di Tecnologia, Via Enrico Melen 83, Building B, 16152, Genoa, Italy
| | - Gaetano Ivan Dellino
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, 20139, Milan, Italy.,Department of Oncology and Hemato-Oncology, University of Milan, 20122, Milan, Italy
| | - Mario Faretta
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, 20139, Milan, Italy
| | - Giuseppe Vicidomini
- Molecular Microscopy and Spectroscopy, CHT Erzelli, Istituto Italiano di Tecnologia, Via Enrico Melen 83, Building B, 16152, Genoa, Italy
| | - Pier Giuseppe Pelicci
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, 20139, Milan, Italy.,Department of Oncology and Hemato-Oncology, University of Milan, 20122, Milan, Italy
| | - Paolo Bianchini
- Nanoscopy and NIC@IIT, CHT Erzelli, Istituto Italiano di Tecnologia, Via Enrico Melen 83, Building B, 16152, Genoa, Italy
| | - Alberto Diaspro
- Nanoscopy and NIC@IIT, CHT Erzelli, Istituto Italiano di Tecnologia, Via Enrico Melen 83, Building B, 16152, Genoa, Italy.,DIFILAB, Department of Physics, University of Genoa, via Dodecaneso 33, 16143, Genoa, Italy
| | - Luca Lanzanò
- Department of Physics and Astronomy "Ettore Majorana", University of Catania, Via S. Sofia 64, 95123, Catania, Italy. .,Nanoscopy and NIC@IIT, CHT Erzelli, Istituto Italiano di Tecnologia, Via Enrico Melen 83, Building B, 16152, Genoa, Italy.
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