Axial-Ligand-Cleavable Silicon Phthalocyanines Triggered by Near-Infrared Light toward Design of Photosensitizers for Photoimmunotherapy

Axial-Ligand-Cleavable Silicon Phthalocyanines Triggered by Near-Infrared Light toward Design of Photosensitizers for Photoimmunotherapy | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Axial-Ligand-Cleavable Silicon Phthalocyanines Triggered by Near-Infrared Light toward Design of Photosensitizers for Photoimmunotherapy Hideo Takakura, Shino Matsuhiro, Masato Kobayashi, Yuto Goto, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-904362/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Dec, 2021 Read the published version in Journal of Photochemistry and Photobiology A: Chemistry → Version 1 posted You are reading this latest preprint version Abstract Near-infrared photoimmunotherapy (NIR-PIT) is a novel phototherapy for the treatment of cancer that uses NIR light and conjugates of antibody-IR700, a silicon phthalocyanine photosensitizer. A key feature of NIR-PIT is light-induced axial ligand cleavage of IR700, which finally causes cytotoxicity. Here, we focused on protonation of the axial ligand on the IR700 anion radical during the photochemical process. The Gibbs energy in the protonation reaction of IR700 derivatives with different axial ligands was calculated. These calculations suggested the order of the cleavage efficiency corresponds to the basicity of the axial ligand (i.e. alkoxy > siloxy (IR700) > phenoxy ≈ oxycarbonyl), which was confirmed by the photoirradiation experiments with synthesized compounds. Thus, axial ligand cleavage is significantly dependent on the basicity of the axial ligand. Our findings suggest that PIT reagent with an IR700 derivative bearing alkoxy group would show better efficacy than IR700. Nuclear Medicine & Medical Imaging Clinical Pharmacology Near-infrared photoimmunotherapy (NIR-PIT) IRDye700DX (IR700) silicon phthalocyanine (SiPc) near-infrared (NIR) HER2 Full Text Additional Declarations Yes there is potential Competing Interest. M.O. has received research grants and consultation fees from Rakuten Medical, Inc. Supplementary Files SupportingInformationNIRCommunChem.pdf Cite Share Download PDF Status: Published Journal Publication published 01 Dec, 2021 Read the published version in Journal of Photochemistry and Photobiology A: Chemistry → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-904362","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":52470426,"identity":"adb0181f-92bc-468d-a168-5766ce10b2d1","order_by":0,"name":"Hideo Takakura","email":"","orcid":"","institution":"Hokkaido Univeristy","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Hideo","middleName":"","lastName":"Takakura","suffix":""},{"id":52470427,"identity":"2794ae20-b8dc-4234-9980-bf9355a8a735","order_by":1,"name":"Shino Matsuhiro","email":"","orcid":"","institution":"Hokkaido 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A key feature of NIR-PIT is light-induced axial ligand cleavage of IR700, which finally causes cytotoxicity. Here, we focused on protonation of the axial ligand on the IR700 anion radical during the photochemical process. The Gibbs energy in the protonation reaction of IR700 derivatives with different axial ligands was calculated. These calculations suggested the order of the cleavage efficiency corresponds to the basicity of the axial ligand (i.e. alkoxy \u003e siloxy (IR700) \u003e phenoxy ≈ oxycarbonyl), which was confirmed by the photoirradiation experiments with synthesized compounds. Thus, axial ligand cleavage is significantly dependent on the basicity of the axial ligand. 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