Two-Photon Absorption: An Open Door to the NIR-II Biological Window?
Open accessAbstract
The way in which photons travel through biological tissues and subsequently become scattered or absorbed is a key limitation for traditional optical medical imaging techniques using visible light. In contrast, near-infrared wavelengths, in particular those above 1000 nm, penetrate deeper in tissues and undergo less scattering and cause less photo-damage, which describes the so-called “second biological transparency window”. Unfortunately, current dyes and imaging probes have severely limited absorption profiles at such long wavelengths, and molecular engineering of novel NIR-II dyes can be a tedious and unpredictable process, which limits access to this optical window and impedes further developments. Two-photon (2P) absorption not only provides convenient access to this window by doubling the absorption wavelength of dyes, but also increases the possible resolution. This review aims to provide an update on the available 2P instrumentation and 2P luminescent materials available for optical imaging in the NIR-II window.
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Light in the 1000 to 2000 nm spectrum can increase penetration depth into biological tissues, improve image resolution, reduce tissue autofluorescence, and aid image-based diagnostics.
“For published data assembled by Shaw et al.,59 it was shown that light in the 1000 to 2000 nm spectrum can increase penetration depth into biological tissues, improve image resolution, reduce tissue autofluorescence, and aid image-based diagnostics.”
From Effect of skin color on optical properties and the implications for medical optical technologies: a review (2024) · cites this paper as [59]
NIR II and III have been exploited for deep-tissue high-resolution optical imaging in other tissues.
“Similar has been shown to be true for other tissues, and NIR II and III have also been exploited for deep-tissue high-resolution optical imaging [27,31–36].”
From Relevance and utility of the in-vivo and ex-vivo optical properties of the skin reported in the literature: a review [Invited] (2023) · cites this paper as [34]
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References 183 · Cited by 75
Research works printed but not linked: 2
- Eisele M. (2020). Simplifying Two-Photon Microscopy. Wiley Analytical Science.
- Zhang N.-N. Lu C.-Y. Chen M.-J. Xu X.-L. Shu G.-F. Du Y.-Z. (2021). Recent Advances in Near-Infrared II Imaging Technology for Biological Detection. J. Nanobiotechnol 19, 132. 10.1186/s12951-021-00870-z PMC8112043 33971910 · DOI
- Authors
- Shaw, P. A., Forsyth, E., Haseeb, F., Yang, S., Bradley, M., & Klausen, M.
- Affiliations
- University of Edinburgh (GB)
- Corresponding author
- Klausen, Maxime
- Venue
- Frontiers in Chemistry
- Publisher
- Frontiers Media SA
- Published
- 2022-06-24
- Volume
- 10
- Pages
- 921354-921354
- ISSN
- 2296-2646 (ISSN-L)
- PMC
- PMC9263132
- OpenAlex
- W4283359935
- Cited by
- 75
- References
- 183
- Citations by year
- 2026: 15 · 2025: 28 · 2024: 14 · 2023: 17 · 2022: 1
- FWCI
- 2.54
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Frontiers in Chemistry (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- Edinburgh Research Explorer (University of Edinburgh) (publishedVersion, cc-by)
- Queen Mary Research Online (Queen Mary University of London) (submittedVersion, cc-by)
- HAL (submittedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Funders
- Engineering and Physical Sciences Research Council (EP/T020997 EP/R018669/1 EP/R005257 EP/L016559)
- Topics
- Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Optical Imaging and Spectroscopy Techniques
- Physical Sciences › Engineering › Biomedical Engineering › Nonlinear Optical Materials Studies
- Physical Sciences › Materials Science › Materials Chemistry › Luminescence and Fluorescent Materials
- Keywords
- two-photon absorption, NIR-II window, near-infrared dyes, two-photon luminescence, optical imaging, tissue penetration depth, light scattering
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