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10 pages, 2788 KiB

Open AccessArticle

Mechanical Force-Induced Blue-Shifted and Enhanced Emission for AIEgens

by Chang-Sheng Guo, Xiao-Long Su, Yu-Ting Yin, Bo-Xuan Zhang, Xin-Yi Liu, Rui-Peng Wang, Pu Chen, Hai-Tao Feng and Ben-Zhong Tang

Biosensors 2022, 12(11), 1055; https://doi.org/10.3390/bios12111055 - 21 Nov 2022

Cited by 1 | Viewed by 1880

Abstract

Mechanochromic (MC) luminescence of organic molecules has been emerging as a promising smart material for optical recording and memory devices. At the same time, pressure-induced blue-shifted and enhanced luminescence are rarely reported now. Herein, a series of cyanostilbene-based AIEgens with different substituents were [...] Read more.

Mechanochromic (MC) luminescence of organic molecules has been emerging as a promising smart material for optical recording and memory devices. At the same time, pressure-induced blue-shifted and enhanced luminescence are rarely reported now. Herein, a series of cyanostilbene-based AIEgens with different substituents were synthesized to evaluate the influence of morphology transformation and push-pull electronic effect on the MC luminescence. Among these luminophores, compound 1 with one cyano group and diethylamino group was more susceptible to mechanical stimuli and obtained blue-shifted and enhanced fluorescence in response to anisotropic grinding. Powder X-ray diffraction patterns indicated that the MC behaviors were ascribed to the solid-state morphology transition from crystal-to-crystal. Analysis of crystal structures revealed that loose molecular packing is a key factor for high high-contrast MC luminescence. The smart molecular design, together with the excellent performance, verified that luminophores with twisted structures are ideal candidates for MC luminogens. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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12 pages, 4409 KiB

Open AccessArticle

A Ratiometric Organic Fluorescent Nanogel Thermometer for Highly Sensitive Temperature Sensing

by Chao Wang, Xianhao Zhao, Kaiyu Wu, Shuyi Lv and Chunlei Zhu

Biosensors 2022, 12(9), 702; https://doi.org/10.3390/bios12090702 - 01 Sep 2022

Cited by 3 | Viewed by 1876

Abstract

Sensing temperature in biological systems is of great importance, as it is constructive to understanding various physiological and pathological processes. However, the realization of highly sensitive temperature sensing with organic fluorescent nanothermometers remains challenging. In this study, we report a ratiometric fluorescent nanogel [...] Read more.

Sensing temperature in biological systems is of great importance, as it is constructive to understanding various physiological and pathological processes. However, the realization of highly sensitive temperature sensing with organic fluorescent nanothermometers remains challenging. In this study, we report a ratiometric fluorescent nanogel thermometer and study its application in the determination of bactericidal temperature. The nanogel is composed of a polarity-sensitive aggregation-induced emission luminogen with dual emissions, a thermoresponsive polymer with a phase transition function, and an ionic surface with net positive charges. During temperature-induced phase transition, the nanogel exhibits a reversible and sensitive spectral change between a red-emissive state and a blue-emissive state by responding to the hydrophilic-to-hydrophobic change in the local environment. The correlation between the emission intensity ratio of the two states and the external temperature is delicately established, and the maximum relative thermal sensitivities of the optimal nanogel are determined to be 128.42 and 68.39% °C⁻¹ in water and a simulated physiological environment, respectively. The nanogel is further applied to indicate the bactericidal temperature in both visual and ratiometric ways, holding great promise in the rapid prediction of photothermal antibacterial effects and other temperature-related biological events. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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18 pages, 5599 KiB

Open AccessArticle

Aggregation-Induced Ignition of Near-Infrared Phosphorescence of Non-Symmetric [Pt(C^N*N’^C’)] Complex in Poly(caprolactone)-based Block Copolymer Micelles: Evaluating the Alternative Design of Near-Infrared Oxygen Biosensors

by Nina A. Zharskaia, Anastasia I. Solomatina, Yu-Chan Liao, Ekaterina E. Galenko, Alexander F. Khlebnikov, Pi-Tai Chou, Pavel S. Chelushkin and Sergey P. Tunik

Biosensors 2022, 12(9), 695; https://doi.org/10.3390/bios12090695 - 28 Aug 2022

Cited by 4 | Viewed by 1765

Abstract

In the present work, we described the preparation and characterization of the micelles based on amphiphilic poly(ε-caprolactone-block-ethylene glycol) block copolymer (PCL-b-PEG) loaded with non-symmetric [Pt(C^N*N’^C’)] complex (Pt1) (where C^N*N’^C’: 6-(phenyl(6-(thiophene-2-yl)pyridin-2-yl)amino)-2-(tyophene-2-yl)nicotinate). The obtained nanospecies displayed the [...] Read more.

In the present work, we described the preparation and characterization of the micelles based on amphiphilic poly(ε-caprolactone-block-ethylene glycol) block copolymer (PCL-b-PEG) loaded with non-symmetric [Pt(C^N*N’^C’)] complex (Pt1) (where C^N*N’^C’: 6-(phenyl(6-(thiophene-2-yl)pyridin-2-yl)amino)-2-(tyophene-2-yl)nicotinate). The obtained nanospecies displayed the ignition of near-infrared (NIR) phosphorescence upon an increase in the content of the platinum complexes in the micelles, which acted as the major emission component at 12 wt.% of Pt1. Emergence of the NIR band at 780 nm was also accompanied by a 3-fold growth of the quantum yield and an increase in the two-photon absorption cross-section that reached the value of 450 GM. Both effects are believed to be the result of progressive platinum complex aggregation inside hydrophobic poly(caprolactone) cores of block copolymer micelles, which has been ascribed to aggregation induced emission (AIE). The resulting phosphorescent (Pt1@PCL-b-PEG) micelles demonstrated pronounced sensitivity towards molecular oxygen, the key intracellular bioanalyte. The detailed photophysical analysis of the AIE phenomena revealed that the NIR emission most probably occurred due to the excimeric excited state of the ³MMLCT character. Evaluation of the Pt1@PCL-b-PEG efficacy as a lifetime intracellular oxygen biosensor carried out in CHO-K1 live cells demonstrated the linear response of the probe emission lifetime towards this analyte accompanied by a pronounced influence of serum albumin on the lifetime response. Nevertheless, Pt1@PCL-b-PEG can serve as a semi-quantitative lifetime oxygen nanosensor. The key result of this study consists of the demonstration of an alternative approach for the preparation of NIR biosensors by taking advantage of in situ generation of NIR emission due to the nanoconfined aggregation of Pt (II) complexes inside the micellar nanocarriers. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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11 pages, 2040 KiB

Open AccessArticle

A Fast-Response AIE-Active Ratiometric Fluorescent Probe for the Detection of Carboxylesterase

by Mengting Xia, Chunbin Li, Lingxiu Liu, Yumao He, Yongdong Li, Guoyu Jiang and Jianguo Wang

Biosensors 2022, 12(7), 484; https://doi.org/10.3390/bios12070484 - 03 Jul 2022

Cited by 5 | Viewed by 2255

Abstract

Hepatocellular carcinoma (HCC) is associated with a high mortality rate worldwide. The therapeutic outcomes can be significantly improved if diagnosis and treatment are initiated earlier in the disease process. Recently, the carboxylesterase (CaE) activity/level in human plasma was reported to be a novel [...] Read more.

Hepatocellular carcinoma (HCC) is associated with a high mortality rate worldwide. The therapeutic outcomes can be significantly improved if diagnosis and treatment are initiated earlier in the disease process. Recently, the carboxylesterase (CaE) activity/level in human plasma was reported to be a novel serological biomarker candidate for HCC. In this article, we fabricated a new fluorescent probe with AIE characteristics for the rapid detection of CaE with a more reliable ratiometric response mode. The TCFISE probe showed high sensitivity (LOD: 93.0 μU/mL) and selectivity toward CaE. Furthermore, the good pH stability, superior resistance against photobleaching, and low cytotoxicity highlight the high potential of the TCFISE probe for application in the monitoring of CaE activity in complex biological samples and in live cells, tissues, and animals. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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10 pages, 4250 KiB

Open AccessCommunication

Dual Molecular Design toward a Lysosome-Tagged AIEgen and Heavy-Atom-Free Photosensitizers for Hypoxic Cancer Photodynamic Therapy

by Thanh Chung Pham, Thi Thuy Hang Hoang, Yeonghwan Choi, Seongman Lee, Sang-Woo Joo, Gun Kim, Dongwon Kim, Ok-Sang Jung and Songyi Lee

Biosensors 2022, 12(6), 420; https://doi.org/10.3390/bios12060420 - 15 Jun 2022

Cited by 3 | Viewed by 2137

Abstract

To date, a large number of photosensitizers (PS) have introduced heavy atoms to improve the ISC process and ¹O₂ generation. However, they often show low efficiency in hypoxic conditions, aggregate states, and turn-off PDT in the dark. Besides that, the toxicity [...] Read more.

To date, a large number of photosensitizers (PS) have introduced heavy atoms to improve the ISC process and ¹O₂ generation. However, they often show low efficiency in hypoxic conditions, aggregate states, and turn-off PDT in the dark. Besides that, the toxicity of heavy metals is also concerned. Therefore, we developed lysosome-targeted heavy-metal-free PS (3S and 4S) based on thionated naphthalimide for hypoxic cancer photodynamic therapy (PDT), not only under white light but also in the dark via thermal-induced ¹O₂ generation. AIEgen (3O and 4O) were prepared for studying the PDT action of PSs (3S and 4S) in lysosome and aggregate state. We also examined the photophysical properties of AIEgen (3O and 4O) and PS (3S and 4S) by UV–vis absorption, fluorescent emission spectra, and theoretical calculations. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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19 pages, 5318 KiB

Open AccessArticle

Brush-like Polymer Prodrug with Aggregation-Induced Emission Features for Precise Intracellular Drug Tracking

by Sanaz Naghibi, Soheila Sabouri, Yuning Hong, Zhongfan Jia and Youhong Tang

Biosensors 2022, 12(6), 373; https://doi.org/10.3390/bios12060373 - 29 May 2022

Cited by 4 | Viewed by 2378

Abstract

In this study, a brush-like polymer with aggregation-induced emission (AIE) features was synthesized for drug delivery and intracellular drug tracking. The polymer consisting of tetraphenylethene (TPE) chain-end as well as oligo-poly (ethylene glycol) (PEG) and hydrazine functionalities was successfully synthesized through copper (0)-mediated [...] Read more.

In this study, a brush-like polymer with aggregation-induced emission (AIE) features was synthesized for drug delivery and intracellular drug tracking. The polymer consisting of tetraphenylethene (TPE) chain-end as well as oligo-poly (ethylene glycol) (PEG) and hydrazine functionalities was successfully synthesized through copper (0)-mediated reversible-deactivation radical polymerization (Cu⁰-mediated RDRP). Anticancer drug doxorubicin (DOX) was conjugated to the polymer and formed a prodrug named TPE-PEGA-Hyd-DOX, which contains 11% DOX. The hydrazone between DOX and polymer backbone is a pH-sensitive linkage that can control the release of DOX in slightly acidic conditions, which can precisely control the DOX release rate. The drug release of 10% after 96 h in normal cell environments compared with about 40% after 24 h in cancer cell environments confirmed the influence of the hydrazone bond. The ratiometric design of fluorescent intensities with peaks at 410 nm (emission due to AIE feature of TPE) and 600 nm (emission due to ACQ feature of DOX) provides an excellent opportunity for this product as a precise intracellular drug tracker. Cancer cells confocal microscopy showed negligible DOX solution uptake, but an intense green emission originated from prodrug uptake. Moreover, a severe red emission in the DOX channel confirmed a promising level of drug release from the prodrug in the cytoplasm. The merged images of cancer cells confirmed the high performance of the TPE-PEGA-Hyd-DOX compound in the viewpoints of cellular uptake and drug release. This polymer prodrug successfully demonstrates low cytotoxicity in healthy cells and high performance in killing cancer cells. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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24 pages, 3174 KiB

Open AccessArticle

Visualising the Emerging Platform of Using Microalgae as a Sustainable Bio-Factory for Healthy Lipid Production through Biocompatible AIE Probes

by AHM Mohsinul Reza, Sharmin Ferdewsi Rakhi, Xiaochen Zhu, Youhong Tang and Jianguang Qin

Biosensors 2022, 12(4), 208; https://doi.org/10.3390/bios12040208 - 31 Mar 2022

Cited by 4 | Viewed by 2027

Abstract

Nowadays, a particular focus is using microalgae to get high-valued health beneficiary lipids. The precise localisation of the lipid droplets (LDs) and biochemical changes are crucial to portray the lipid production strategy in algae, but it requires an in vivo tool to rapidly [...] Read more.

Nowadays, a particular focus is using microalgae to get high-valued health beneficiary lipids. The precise localisation of the lipid droplets (LDs) and biochemical changes are crucial to portray the lipid production strategy in algae, but it requires an in vivo tool to rapidly visualise LD distribution. As a novel strategy, this study focuses on detecting lipid bioaccumulation in a green microalga, Chlamydomonas reinhardtii using the aggregation-induced emission (AIE) based probe, 2-DPAN (C₂₄H₁₈N₂O). As the messenger molecule and stress biomarker, hydrogen peroxide (H₂O₂) activity was detected in lipid synthesis with the AIE probe, TPE-BO (C₃₈H₄₂B₂O₄). Distinctive LDs labelled with 2-DPAN have elucidated the lipid inducing conditions, where more health beneficiary α-linolenic acid has been produced. TPE-BO labelled H₂O₂ have clarified the involvement of H₂O₂ during lipid biogenesis. The co-staining procedure with traditional green BODIPY dye and red chlorophyll indicates that 2-DPAN is suitable for multicolour LD imaging. Compared with BODIPY, 2-DPAN was an efficient sample preparation technique without the washing procedure. Thus, 2-DPAN could improve traditional fluorescent probes currently used for lipid imaging. In addition, the rapid, wash-free, multicolour AIE-based in vivo probe in the study of LDs with 2-DPAN could advance the research of lipid production in microalgae. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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Review

Jump to: Research

21 pages, 19546 KiB

Open AccessReview

Ir(III) Complexes with AIE Characteristics for Biological Applications

by Yu Pei, Yan Sun, Meijia Huang, Zhijun Zhang, Dingyuan Yan, Jie Cui, Dongxia Zhu, Zebing Zeng, Dong Wang and Benzhong Tang

Biosensors 2022, 12(12), 1104; https://doi.org/10.3390/bios12121104 - 01 Dec 2022

Cited by 9 | Viewed by 1947

Abstract

Both biological process detection and disease diagnosis on the basis of luminescence technology can provide comprehensive insights into the mechanisms of life and disease pathogenesis and also accurately guide therapeutics. As a family of prominent luminescent materials, Ir(III) complexes with aggregation-induced emission (AIE) [...] Read more.

Both biological process detection and disease diagnosis on the basis of luminescence technology can provide comprehensive insights into the mechanisms of life and disease pathogenesis and also accurately guide therapeutics. As a family of prominent luminescent materials, Ir(III) complexes with aggregation-induced emission (AIE) tendency have been recently explored at a tremendous pace for biological applications, by virtue of their various distinct advantages, such as great stability in biological media, excellent fluorescence properties and distinctive photosensitizing features. Significant breakthroughs of AIE-active Ir(III) complexes have been achieved in the past few years and great progress has been witnessed in the construction of novel AIE-active Ir(III) complexes and their applications in organelle-specific targeting imaging, multiphoton imaging, biomarker-responsive bioimaging, as well as theranostics. This review systematically summarizes the basic concepts, seminal studies, recent trends and perspectives in this area. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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35 pages, 11266 KiB

Open AccessReview

Aggregation-Induced Emission Luminogens for Enhanced Photodynamic Therapy: From Organelle Targeting to Tumor Targeting

by Jiahe Zhou, Fen Qi, Yuncong Chen, Shuren Zhang, Xiaoxue Zheng, Weijiang He and Zijian Guo

Biosensors 2022, 12(11), 1027; https://doi.org/10.3390/bios12111027 - 16 Nov 2022

Cited by 1 | Viewed by 2102

Abstract

Photodynamic therapy (PDT) has attracted much attention in the field of anticancer treatment. However, PDT has to face challenges, such as aggregation caused by quenching of reactive oxygen species (ROS), and short ¹O₂ lifetime, which lead to unsatisfactory therapeutic effect. Aggregation-induced [...] Read more.

Photodynamic therapy (PDT) has attracted much attention in the field of anticancer treatment. However, PDT has to face challenges, such as aggregation caused by quenching of reactive oxygen species (ROS), and short ¹O₂ lifetime, which lead to unsatisfactory therapeutic effect. Aggregation-induced emission luminogen (AIEgens)-based photosensitizers (PSs) showed enhanced ROS generation upon aggregation, which showed great potential for hypoxic tumor treatment with enhanced PDT effect. In this review, we summarized the design strategies and applications of AIEgen-based PSs with improved PDT efficacy since 2019. Firstly, we introduce the research background and some basic knowledge in the related field. Secondly, the recent approaches of AIEgen-based PSs for enhanced PDT are summarized in two categories: (1) organelle-targeting PSs that could cause direct damage to organelles to enhance PDT effects, and (2) PSs with tumor-targeting abilities to selectively suppress tumor growth and reduce side effects. Finally, current challenges and future opportunities are discussed. We hope this review can offer new insights and inspirations for the development of AIEgen-based PSs for better PDT effect. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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19 pages, 9450 KiB

Open AccessReview

Type I Photosensitizers Based on Aggregation-Induced Emission: A Rising Star in Photodynamic Therapy

by Danxia Li, Peiying Liu, Yonghong Tan, Zhijun Zhang, Miaomiao Kang, Dong Wang and Ben Zhong Tang

Biosensors 2022, 12(9), 722; https://doi.org/10.3390/bios12090722 - 04 Sep 2022

Cited by 9 | Viewed by 2821

Abstract

Photodynamic therapy (PDT), emerging as a minimally invasive therapeutic modality with precise controllability and high spatiotemporal accuracy, has earned significant advancements in the field of cancer and other non-cancerous diseases treatment. Thereinto, type I PDT represents an irreplaceable and meritorious part in contributing [...] Read more.

Photodynamic therapy (PDT), emerging as a minimally invasive therapeutic modality with precise controllability and high spatiotemporal accuracy, has earned significant advancements in the field of cancer and other non-cancerous diseases treatment. Thereinto, type I PDT represents an irreplaceable and meritorious part in contributing to these delightful achievements since its distinctive hypoxia tolerance can perfectly compensate for the high oxygen-dependent type II PDT, particularly in hypoxic tissues. Regarding the diverse type I photosensitizers (PSs) that light up type I PDT, aggregation-induced emission (AIE)-active type I PSs are currently arousing great research interest owing to their distinguished AIE and aggregation-induced generation of reactive oxygen species (AIE-ROS) features. In this review, we offer a comprehensive overview of the cutting-edge advances of novel AIE-active type I PSs by delineating the photophysical and photochemical mechanisms of the type I pathway, summarizing the current molecular design strategies for promoting the type I process, and showcasing current bioapplications, in succession. Notably, the strategies to construct highly efficient type I AIE PSs were elucidated in detail from the two aspects of introducing high electron affinity groups, and enhancing intramolecular charge transfer (ICT) intensity. Lastly, we present a brief conclusion, and a discussion on the current limitations and proposed opportunities. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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16 pages, 4678 KiB

Open AccessReview

AIEgen-Peptide Bioprobes for the Imaging of Organelles

by Bochao Chen, Haotong Yuan, Wei Zhang, Jingjing Hu, Xiaoding Lou and Fan Xia

Biosensors 2022, 12(8), 667; https://doi.org/10.3390/bios12080667 - 22 Aug 2022

Cited by 5 | Viewed by 2117

Abstract

Organelles are important subsystems of cells. The damage and inactivation of organelles are closely related to the occurrence of diseases. Organelles’ functional activity can be observed by fluorescence molecular tools. Nowadays, a series of aggregation-induced emission (AIE) bioprobes with organelles-targeting ability have emerged, [...] Read more.

Organelles are important subsystems of cells. The damage and inactivation of organelles are closely related to the occurrence of diseases. Organelles’ functional activity can be observed by fluorescence molecular tools. Nowadays, a series of aggregation-induced emission (AIE) bioprobes with organelles-targeting ability have emerged, showing great potential in visualizing the interactions between probes and different organelles. Among them, AIE luminogen (AIEgen)-based peptide bioprobes have attracted more and more attention from researchers due to their good biocompatibility and photostability and abundant diversity. In this review, we summarize the progress of AIEgen-peptide bioprobes in targeting organelles, including the cell membrane, nucleus, mitochondria, lysosomes and endoplasmic reticulum, in recent years. The structural characteristics and biological applications of these bioprobes are discussed, and the development prospect of this field is forecasted. It is hoped that this review will provide guidance for the development of AIEgen-peptide bioprobes at the organelles level and provide a reference for related biomedical research. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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25 pages, 16560 KiB

Open AccessReview

Reactive Species-Activatable AIEgens for Biomedical Applications

by Xiaoying Kang, Yue Li, Shuai Yin, Wen Li and Ji Qi

Biosensors 2022, 12(8), 646; https://doi.org/10.3390/bios12080646 - 17 Aug 2022

Cited by 5 | Viewed by 2855

Abstract

Precision medicine requires highly sensitive and specific diagnostic strategies with high spatiotemporal resolution. Accurate detection and monitoring of endogenously generated biomarkers at the very early disease stage is of extensive importance for precise diagnosis and treatment. Aggregation-induced emission luminogens (AIEgens) have emerged as [...] Read more.

Precision medicine requires highly sensitive and specific diagnostic strategies with high spatiotemporal resolution. Accurate detection and monitoring of endogenously generated biomarkers at the very early disease stage is of extensive importance for precise diagnosis and treatment. Aggregation-induced emission luminogens (AIEgens) have emerged as a new type of excellent optical agents, which show great promise for numerous biomedical applications. In this review, we highlight the recent advances of AIE-based probes for detecting reactive species (including reactive oxygen species (ROS), reactive nitrogen species (RNS), reactive sulfur species (RSS), and reactive carbonyl species (RCS)) and related biomedical applications. The molecular design strategies for increasing the sensitivity, tuning the response wavelength, and realizing afterglow imaging are summarized, and theranostic applications in reactive species-related major diseases such as cancer, inflammation, and vascular diseases are reviewed. The challenges and outlooks for the reactive species-activatable AIE systems for disease diagnostics and therapeutics are also discussed. This review aims to offer guidance for designing AIE-based specifically activatable optical agents for biomedical applications, as well as providing a comprehensive understanding about the structure–property application relationships. We hope it will inspire more interesting researches about reactive species-activatable probes and advance clinical translations. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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29 pages, 9373 KiB

Open AccessReview

Pyrene-Based AIE Active Materials for Bioimaging and Theranostics Applications

by Muthaiah Shellaiah and Kien-Wen Sun

Biosensors 2022, 12(7), 550; https://doi.org/10.3390/bios12070550 - 21 Jul 2022

Cited by 38 | Viewed by 3803

Abstract

Aggregation-induced emission (AIE) is a unique research topic and property that can lead to a wide range of applications, including cellular imaging, theranostics, analyte quantitation and the specific detection of biologically important species. Towards the development of the AIE-active materials, many aromatic moieties [...] Read more.

Aggregation-induced emission (AIE) is a unique research topic and property that can lead to a wide range of applications, including cellular imaging, theranostics, analyte quantitation and the specific detection of biologically important species. Towards the development of the AIE-active materials, many aromatic moieties composed of tetraphenylethylene, anthracene, pyrene, etc., have been developed. Among these aromatic moieties, pyrene is an aromatic hydrocarbon with a polycyclic flat structure containing four fused benzene rings to provide an unusual electron delocalization feature that is important in the AIE property. Numerous pyrene-based AIE-active materials have been reported with the AIE property towards sensing, imaging and theranostics applications. Most importantly, these AIE-active pyrene moieties exist as small molecules, Schiff bases, polymers, supramolecules, metal-organic frameworks, etc. This comprehensive review outlines utilizations of AIE-active pyrene-based materials on the imaging and theranostics studies. Moreover, the design and synthesis of these pyrene-based molecules are delivered with discussions on their future scopes. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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24 pages, 16174 KiB

Open AccessReview

AIE-Active Photosensitizers: Manipulation of Reactive Oxygen Species Generation and Applications in Photodynamic Therapy

by Hao Yu, Binjie Chen, Huiming Huang, Zhentao He, Jiangman Sun, Guan Wang, Xinggui Gu and Ben Zhong Tang

Biosensors 2022, 12(5), 348; https://doi.org/10.3390/bios12050348 - 18 May 2022

Cited by 27 | Viewed by 4946

Abstract

Photodynamic therapy (PDT) is a non-invasive approach for tumor elimination that is attracting more and more attention due to the advantages of minimal side effects and high precision. In typical PDT, reactive oxygen species (ROS) generated from photosensitizers play the pivotal role, determining [...] Read more.

Photodynamic therapy (PDT) is a non-invasive approach for tumor elimination that is attracting more and more attention due to the advantages of minimal side effects and high precision. In typical PDT, reactive oxygen species (ROS) generated from photosensitizers play the pivotal role, determining the efficiency of PDT. However, applications of traditional PDT were usually limited by the aggregation-caused quenching (ACQ) effect of the photosensitizers employed. Fortunately, photosensitizers with aggregation-induced emission (AIE-active photosensitizers) have been developed with biocompatibility, effective ROS generation, and superior absorption, bringing about great interest for applications in oncotherapy. In this review, we review the development of AIE-active photosensitizers and describe molecule and aggregation strategies for manipulating photosensitization. For the molecule strategy, we describe the approaches utilized for tuning ROS generation by attaching heavy atoms, constructing a donor-acceptor effect, introducing ionization, and modifying with activatable moieties. The aggregation strategy to boost ROS generation is reviewed for the first time, including consideration of the aggregation of photosensitizers, polymerization, and aggregation microenvironment manipulation. Moreover, based on AIE-active photosensitizers, the cutting-edge applications of PDT with NIR irradiated therapy, activatable therapy, hypoxic therapy, and synergistic treatment are also outlined. Full article

(This article belongs to the Special Issue Development of Aggregation-Induced Emission Materials and Their Applications in Biosensing, Bioimaging and Theranostics)

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