Abstract
Reaction of porphycene isothiocyanates with primary and secondary amines leads to the formation of thiazolo[4,5-c]porphycenes, with a substantial shift in the absorption and fluorescence spectra. The conjugates show fluorescence in the near-infrared and are capable of photosensitizing the production of the cytotoxic species singlet oxygen.
Highlights
Theranostic nanomedicine is an emerging therapeutic strategy that combines a contrast agent and a drug on a single nanoplatform for enhanced diagnosis and treatment of localised diseases.1a Of particular interest are photoactivatable theranostic agents that allow simultaneous fluorescence imaging and localised generation of cytotoxic species.1b,c Current research efforts are directed to the development of theranostic labels that show absorption and emission in the red and near-infrared spectral range,2a as well as strong and selective binding to proteins and nanoparticles.2b Several click reactions have been developed to this end, employing reactive groups such as the isothiocyanate (ITC) for conjugation to free amino residues,2c,d maleimide for cysteine-reduced thiol groups,2e,f and carbodiimide for carboxyl groups.2g
A common and severe drawback of current labels is that the optical and fluorescence properties of the conjugates are not too different from those of the unbound probes, which makes it very difficult to differentiate between covalent adducts and non-specific complexes.2c The latter pose a serious problem to bioconjugate-based biological assays and therapies as they can be released into the biological milieu, altering their results
In the domain of fluorescence, the conventional solution to this problem is the development of turn-on labels that increase their fluorescence intensity upon binding.2h,i since the spectra of the bound and unbound probes are the same and only the intensity changes, good contrast cannot be generally achieved.2j A more robust solution would be the use of probes that change their absorption and fluorescence spectra upon covalent binding since this would allow to selectively excite and monitor the bound and unbound tags
Summary
Theranostic nanomedicine is an emerging therapeutic strategy that combines a contrast agent and a drug on a single nanoplatform for enhanced diagnosis and treatment of localised diseases.1a Of particular interest are photoactivatable theranostic agents that allow simultaneous fluorescence imaging and localised generation of cytotoxic species.1b,c Current research efforts are directed to the development of theranostic labels that show absorption and emission in the red and near-infrared spectral range,2a as well as strong and selective binding to proteins and nanoparticles.2b Several click reactions have been developed to this end, employing reactive groups such as the isothiocyanate (ITC) for conjugation to free amino residues,2c,d maleimide for cysteine-reduced thiol groups,2e,f and carbodiimide for carboxyl groups.2g. Reaction of porphycene isothiocyanates with primary and secondary amines leads to the formation of thiazolo[4,5-c]porphycenes, with a substantial shift in the absorption and fluorescence spectra.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: 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.
