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Gold Nanomaterials at Work in Biomedicine *
Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Xuan Yang, Miaoxin Yang, Pang Bo, Madeline Vara, Younan Xia
In general, the number of Au atoms in each cluster [26, 76, 77, 82, 300, 303–307], the aggregation state of the clusters [308], and the type of capping ligand can all impact the photoluminescence emitted from a sample of Au clusters [309]. Ying and coworkers reported the use of BSA as a matrix to prepare fluorescent Au clusters with a remarkable quantum yield of 6% [82]. Spectroscopy studies further confirmed that the photoluminescence originated from the Au clusters rather than BSA. As shown in Fig. 5.21A, the Au clusters displayed an emission peak at 640 nm, implying the presence of Au25 clusters according to the spherical jellium model, which was supported by the data from MALDI-MS. In another study, Xie and coworkers demonstrated that the strong luminescence from Au(0)@ Au(I)-thiolate clusters could be explained using a mechanism based on aggregation-induced emission (AIE) [308]. As shown in Fig. 5.21B, nonluminescent oligomeric Au(0)@ Au(I)-thiolate clusters could emit strong photoluminescence once the clusters had been induced to aggregate. The wavelength and intensity of the photoluminescence were largely determined by the degree of aggregation. This method was further used to develop highly luminescent Au nanostructures with a quantum yield up to 15%.
Extracellular vesicles: emerging anti-cancer drugs and advanced functionalization platforms for cancer therapy
Published in Drug Delivery, 2022
Manling Wu, Min Wang, Haoyuan Jia, Peipei Wu
The phospholipid bilayer of EVs can be labeled with lipophilic dyes, such as PKH dyes (such as PKH26, PKH67) and carbocyanine dyes (such as DiI, DiD, DiO, and DiR). In addition, EVs can also be labeled with some membrane-permeable compounds (such as CFSE, CFDA, and Calcein-AM). After nearly a decade of efforts and development, aggregation-induced emission (AIE) materials have been developed as a new photosensitizer, which has greatly promoted the development of tumor photodynamic therapy. Zhu et al. designed 4T1 tumor cell-derived EVs loaded with AIE luminogen, which facilitate efficient breast cancer penetration and photodynamic therapy (Zhu et al., 2020). In addition, AIE luminogen has also been reported to exhibit superior labeling efficiency and tracking capability for in vivo real-time imaging of EVs (Cao et al., 2019; 2020). Therefore, AIE luminogen is expected to become an ideal photosensitizer and imaging agent for tumor photodynamic therapy.
A mechanistic insight into benefits of aggregation induced emissive luminogens in cancer
Published in Journal of Drug Targeting, 2021
In this context, the probable usage of luminogens that display aggregation-induced emission (AIE) features in theranostic nanomedicine has as garnered worldwide interest [17–19]. AIEgens own several distinctive benefits such as simple preparation and modification prospects, good biocompatibility, low cytotoxicity, intense and bright emission in aggregate form, large Stokes shift, widely tuneable emission wavelengths, high photobleaching threshold, low background noise, workability at high concentration, on-site activation and turn-on detection feature for specific intracellular analytes, external stimuli or microenvironment [20–27]. Moreover, the perfect nano-aggregation size aids in enhanced permeability and retention (EPR) [28] and improved multimodal imaging and therapy, when compared with some of the conventional theranostic nanomaterials.
Recent CPP-based applications in medicine
Published in Expert Opinion on Drug Delivery, 2019
An interesting cancer imaging approach has been proposed by Cheng et al., who took advantage of the previously described unconventional fluorescence phenomenon called aggregation-induced emission (AIE) effect [44]. Whereas conventional fluorescence imaging is characterized by an aggregation-caused quenching, the AIE-active tetraphenylethene derivative PyTPE is fluorescent in the aggregated state, being non-emissive when dispersed [44]. This property was used to stably ‘label’ more crowded subcellular regions, such as by using nuclear targeting, the cell nuclei. Accordingly, the authors proposed a multifunctional nucleic acid delivery system, composed of three peptide elements: an RGD integrin‐targeting moiety, CPP, NLS signal, all of those conjugated to the above-mentioned fluorophore. Finally, this construct was electrostatically complexed with the nucleic acid cargo. Ultimately, their multifunctional nanosystem offered both diagnostic values from the AIE effect, and antisense against Bcl2 was effective in suppressing tumor in a mouse model [45].