Multilayer Microcapsules for FRET Analysis and Two‐Photon‐Activated Photodynamic Therapy

Abstract

Microcapsules obtained by layer-by-layer assembly provide a good platform for biological analysis owing to their component diversity, multiple binding sites, and controllable wall thickness. Herein, different assembly species were obtained from two-photon dyes and traditional photosensitizers, and further assembled into microcapsules. Fluorescence resonance energy transfer (FRET) was shown to occur between the two-photon dyes and photosensitizers. Confocal laser scanning microscopy (CLSM) with one- and two-photon lasers, fluorescence lifetime imaging microscopy (FLIM), and time-resolved fluorescence spectroscopy were used to analyze the FRET effects in the microcapsules. The FRET efficiency could easily be controlled through changing the assembly sequence. Furthermore, the capsules are phototoxic upon one- or two-photon excitation. These materials are thus expected to be applicable in two-photon-activated photodynamic therapy for deep-tissue treatment.

Photosensitizers for Two‐Photon Excited Photodynamic Therapy

“…The advantages of using nanocarriers lie in their excellent colloid dispersity in water, which enables the solubilization of hydrophobic PSs in physiological conditions and an enhanced accumulation of PSs at tumor sites through an enhanced permeability and retention effect . The currently reported nanoparticles for 2PE‐PDT mainly include carbon‐, silica‐, or gold‐based nanoparticles, semiconductor quantum dots (QDs), and nonconjugated polymer nanostructures …”

“…Recently, Li and co‐workers fabricated multilayer polyelectrolyte microcapsules by the cyclic adsorption of a polycation (poly(allylamine), PAH) and a polyanion (poly(sodium‐ para ‐styrenesulfonate)) on the surface of a MnCO 3 microsphere template using layer‐by‐layer assembly technology. The PAH was labeled with a 2PA dye (FITC) and a PS (RB) to yield the functional components of FITC‐PAH and RB‐PAH, respectively.…”

Photosensitizing properties of hollow microcapsules built by multilayer self-assembly of poly(allylamine hydrochloride) modified with rose Bengal

“…24,25 Such lms can be conveniently functionalized via post-synthetic modication with selected molecules 26 or nanoparticles, 27,28 or by using already functionalized polyelectrolytes. [29][30][31] LbL assembly can be carried out to create lms, but also grown over different templates, such as carbonates microparticles, which aer removal with suitable chelating agents, give raise to hollow microcapsules (HM). 32 Although the use of RB in the assembly of HM was already reported, 30,33 the inuence of different anchoring strategies and its assembly into LbL architectures on their photophysical and photosensitization properties was not studied in detail.…”

“…[29][30][31] LbL assembly can be carried out to create lms, but also grown over different templates, such as carbonates microparticles, which aer removal with suitable chelating agents, give raise to hollow microcapsules (HM). 32 Although the use of RB in the assembly of HM was already reported, 30,33 the inuence of different anchoring strategies and its assembly into LbL architectures on their photophysical and photosensitization properties was not studied in detail. The goals of the present work can be summarized as follows: (i) to synthesize a RB modied PAH polycation (PAH-RB); (ii) to use such PAH-RB polycation for microcapsule formation via LbL with CaCO 3 microspheres as sacricial templates and PSS as counter polyelectrolyte; (iii) to evaluate the effect of polymer conformation and spatial distribution in the photophysical properties of RB; and nally (iv) to assess the photosensitizing properties of such supramolecular assembly using chemical and biological oxidizable targets.…”

Insight into the efficiency of oxygen introduced photodynamic therapy (PDT) and deep PDT against cancers with various assembled nanocarriers

“…Microcapsules fabricated with different assembly sequences (a) and the corresponding lifetime decay curves (b). (Reprinted with permission from Yang, Liu, Han, Sun, and Li (). Copyright 2016, WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) III.…”