Abstract
Photoswitchable fluorescent proteins (PFPs) that can change fluorescence color upon excitation have revolutionized many applications of light such as tracking protein movement, super-resolution imaging, identification of circulating cells, and optical data storage. Nevertheless, the relatively weak fluorescence of PFPs limits their applications in biomedical imaging due to strong tissue autofluorecence background. Conversely, plasmonic nanolasers, also called spasers, have demonstrated potential to generate super-bright stimulated emissions even inside single cells. Nevertheless, the development of photoswitchable spasers that can shift their stimulated emission color in response to light is challenging. Here, we introduce the novel concept of spasers using a PFP layer as the active medium surrounding a plasmonic core. The proof of principle was demonstrated by synthesizing a multilayer nanostructure on the surface of a spherical gold core, with a non-absorbing thin polymer shell and the PFP Dendra2 dispersed in the matrix of a biodegradable polymer. We have demonstrated photoswitching of spontaneous and stimulated emission in these spasers below and above the spasing threshold, respectively, at different spectral ranges. The plasmonic core of the spasers serves also as a photothermal (and potentially photoacoustic) contrast agent, allowing for photothermal imaging of the spasers. These results suggest that multimodal photoswitchable spasers could extend the traditional applications of spasers and PFPs in laser spectroscopy, multicolor cytometry, and theranostics with the potential to track, identify, and kill abnormal cells in circulation.
Highlights
Monitoring of real-time dynamics of CTCs released from primary tumors, identification of dormant cells, and imaging of CTCs colonizing a primary tumor or existing metastasis[15]
We propose the novel concept of photoswitchable spasers by utilizing Photoswitchable fluorescent proteins (PFPs) as an active medium structured around a plasmonic core
The concept of photoswitchable spasers is based on the use of a plasmonic core surrounded by PFPs (Fig. 1)
Summary
Monitoring of real-time dynamics of CTCs released from primary tumors, identification of dormant cells, and imaging of CTCs colonizing a primary tumor (self-seeding) or existing metastasis (reseeding)[15]. The low quantum yield efficiency of most PFPs and their limited multifunctionality and quenching effects could restrict their diagnostic applications in areas such as cancer and infection diagnostics due to the strong auto-fluorescent background of blood and tissue[18,19,20]. To overcome these limitations, we propose the novel concept of photoswitchable spasers by utilizing PFPs as an active medium structured around a plasmonic core. Strong absorption of the plasmonic core can allow us to use spaser as a photothermal contrast agent in imaging-related application. We anticipate broad biomedical application of the photoswitchable spasers with tunable stimulated emissions and photothermal contrasts to PFPs and lasers in spectroscopy, microscopy, and cytometery, with added advantages such as a smaller size, brighter emission, and wider multifunctionality
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.