Polymer-encapsulated organic nanoparticles for fluorescence and photoacoustic imaging

Abstract

Polymer encapsulated organic nanoparticles have recently attracted increasing attention in the biomedical field because of their unique optical properties, easy fabrication and outstanding performance as imaging and therapeutic agents. Of particular importance is the polymer encapsulated nanoparticles containing conjugated polymers (CP) or fluorogens with aggregation induced emission (AIE) characteristics as the core, which have shown significant advantages in terms of tunable brightness, superb photo- and physical stability, good biocompatibility, potential biodegradability and facile surface functionalization. In this review, we summarize the latest advances in the development of polymer encapsulated CP and AIE fluorogen nanoparticles, including preparation methods, material design and matrix selection, nanoparticle fabrication and surface functionalization for fluorescence and photoacoustic imaging. We also discuss their specific applications in cell labeling, targeted in vitro and in vivo imaging, blood vessel imaging, cell tracing, inflammation monitoring and molecular imaging. We specially focus on strategies to fine-tune the nanoparticle property (e.g. size and fluorescence quantum yield) through precise engineering of the organic cores and careful selection of polymer matrices. The review also highlights the merits and limitations of these nanoparticles as well as strategies used to overcome the limitations. The challenges and perspectives for the future development of polymer encapsulated organic nanoparticles are also discussed.

Conjugated polymer nanoparticles with aggregation induced emission characteristics for intracellular Fe3+ sensing

“…15,16 Among the AIE luminogens, tetraphenylethene (TPE) have been intensively investigated because of its facile synthesis, good photostability, and bright fluorescence emission. 12,14,17,18 The approach that introducing TPE moieties to conjugated polymer chain can thus be employed to design and synthesis AIE Additional Supporting Information may be found in the online version of this article. active conjugated polymers to solve the ACQ effect.…”

H 2 O 2 -responsive liposomal nanoprobe for photoacoustic inflammation imaging and tumor theranostics via in vivo chromogenic assay

“…Different from conventional fluorescence or bioluminescence imaging techniques that are suitable mostly for small animals, PA imaging has already moved into clinical trials owing to its significantly improved in vivo imaging depth (as deep as ∼12 cm) and spatial resolution compared with traditional optical imaging modalities (10,11,13). A large variety of nanoscale agents, including both organic and inorganic ones, with absorption in the near-infrared (NIR) "tissue transparent" optical window have been extensively explored as PA imaging probes (14)(15)(16)(17)(18)(19)(20). For example, many types of nanoparticles with strong and constant NIR absorbance are often used for enhanced blood pool imaging and PA imaging of tumors (15,16,19).…”

Smart Supramolecular Nanosystems for Bioimaging and Drug Delivery

“…There is a main obstacle to obtain highly emissive nanoparticles due to aggregation-caused quenching (ACQ) of fluorophores or other non-radiative pathways, which is inconsistent with high brightness and good sensitivity at a low dosage of the contrast agents for fluorescence imaging. By utilizing aggregation-induced emission (AIE) [33][34][35] and aggregation-induced emission enhancement (AIEE) [36,37] mechanisms to obtain high fluorescence in aggregated state or controlling the formation of J-type aggregates of fluorophores are two straight forward solutions.…”