Highly Efficient Photosensitizers with Far-Red/Near-Infrared Aggregation-Induced Emission for In Vitro and In Vivo Cancer Theranostics

Macroporous hydrogel loaded with AIE-photosensitizer for enhanced antibacterial and wounds healing

Effective wound healing requires precise immune regulation, including infection clearance to prevent excessive immune cell activation and polarization of macrophages. Therapeutic systems with combined immunomodulatory effects are crucial. Photodynamic therapy (PDT) is a promising antimicrobial treatment(AIE), with photosensitizers (PSs) playing a central role. The PSs with aggregation-induced emission can efficiently generate reactive oxygen species (ROS) in the aggregated state, making them workable in high concentration. Introduction of a biocompatible carrier is beneficial for the PSs' immobilization and distribution and hydrogels are excellent candidates. It is pursuing to design a PS-hydrogel system with synergetic effect. Type II PSs can generate singlet oxygen under sufficient oxygen. Macroporous hydrogels (MPHs) own superiorities in matter transport and immune cell adhesion reduction. Herein, an AIE-PS, TCSPy+ was designed. With its nanoparticles (NPs), an MPH dressing was developed using a facile extrusion-sequential-photo-crosslinking method based on PEGDA and GelMA. In vitro and in vivo studies demonstrated that TCSPy+@MPH dressing exhibited superior antibacterial activity compared to non-porous hydrogel-based one, significantly inhibiting excessive immune cell activation and polarization of macrophages. The macroporous structure also facilitated inflammatory exudates removal. The synergetic effect with the combined immunomodulation ability allows the dressing to efficiently treat infected wounds, offering an effective strategy to design advanced therapeutic systems for tissue regeneration and immune regulation.

Regioisomerism in NIR-II-emissive semiconducting biradicals for high-performance bioimaging and phototheranostics of tumors

Photothermal agents (PTAs) have received significant attention in medical therapeutic and diagnostic applications. Despite their tremendous development, developing PTAs is challenging when applied to a living body with deep tissue, as it usually leads to attenuated therapeutic efficiency and potential biosafety hazards. Here, we report a molecular isomerization strategy based on NIR-II semiconducting biradicals that boosts the performance of NIR-II phototheranostics. With a stereoisomeric design by precisely manipulating the substitution position of the alkyl side chain, the optimal isomer, α-TBTS, and its nanoparticles (NPs) provide enhanced NIR-II absorption and 63% photothermal conversion capabilities, resulting in efficient photoablation of tumor cells. Most importantly, the relationship between the molecular isomerism of these NIR-II theranostics enables enhanced NIR-II performance, which has been proven by theoretical and ultrafast spectroscopy studies. With all these advantages, the α-TBTS nanoplatform has simultaneously achieved high-resolution whole-body NIR-II angiography and trimodal tumor-targeted imaging in vivo. Moreover, α-TBTS NPs efficiently inhibited tumor growth without recurrence upon NIR-II light irradiation, providing good biosafety. This work demonstrates the feasibility of molecular isomerization in multimodal NIR-II biradical PTAs and thus provides a suitable theranostic agent for high-performance tumor phototheranostics.

AIE Photosensitizer with Tuned Membrane Interactions for Effective-Gram-Negative Bacteria Elimination

Photodynamic antimicrobial therapy (PDAT) for efficient bacterial infection eradication critically relies on photosensitizers (PSs) that can specifically target and disrupt bacterial membranes. However, the complex membrane architecture of Gram-negative bacteria poses a significant challenge to the efficacy of most aggregation-induced emission (AIE) PSs. Herein, we introduce TPQ, an AIE PS meticulously designed to overcome this challenge by incorporating an outer membrane disruption ability, thereby boosting PDAT efficacy against Gram-negative bacteria. TPQ demonstrated excellent microbial imaging and potent PDAT activity against both Gram-positive and Gram-negative bacteria, attributed to its inherent fluorescence, high singlet oxygen generation, and balanced electrostatic and hydrophobic interactions with bacterial membranes. Notably, TPQ achieved exceptional PDAT activity (>97% efficacy) against Gram-negative bacteria while exhibiting minimal cytotoxicity to mammalian cells. Furthermore, TPQ-mediated PDAT effectively healed Escherichia coli-infected wounds on mice models with assured biosafety. This work provides valuable insights into the rational design of AIE PSs and highlights the synergistic effect of membrane disruption for advancing PDAT applications, particularly against recalcitrant Gram-negative bacterial infections.

Phototheranostic Zinc Porphyrin Nanoparticles Triggered by an 808 nm Laser: NIR-II Fluorescence/Photoacoustic Imaging-Guided Combined Photothermal/Photodynamic/NO Therapy

Single-wavelength lasers that trigger intelligently designed multifunctional theranostic nanoplatforms are urgently needed for early cancer diagnosis and imaging-guided therapy. In this study, a novel zinc porphyrin, Por-TR, was fabricated by incorporating thiophene as a donor and introducing electron acceptors on both sides to expand the conjugation. The presence of multiple flexible chains in the molecular structure of Por-TR inhibits π-π stacking, which allows it to form J nanoaggregates when coassembled with DSPE-PEG2000, demonstrating maximum absorption at approximately 808 nm. These Por-TR NPs provide NIR-II fluorescence/PA dual-modal signals for imaging and serve as a combined PTT/PDT therapeutic agent, making them a suitable multifunctional theranostic nanoplatform. To further improve their therapeutic effects, we embedded a thermosensitive NO donor, BNN6, in the Por-TR nanosystem to achieve combined PDT/PTT/NO therapy. Intravenous injection of Por-TR-NO NPs into 4T1 tumor-bearing mice enabled the accurate observation of tumor location via NIR-II fluorescence/PA dual-modal imaging. In vivo therapy results show that the Por-TR-NO NPs exhibited remarkable antitumor efficacy in combined PTT/PDT/NO therapy, which was triggered by an 808 nm laser. Overall, this nanoplatform offers a versatile approach to cancer diagnosis and treatment.

Tuning the Near-Infrared J-Aggregate of a Multicationic Photosensitizer through Molecular Coassembly for Symbiotic Photothermal Therapy and Chemotherapy

Cationic photosensitizers (PSs) offer many intriguing advantages, in addition to generating heat or reactive oxygen species for cancer phototherapy. However, the preparation of cationic PSs with enhanced near-infrared (NIR) absorption remains a significant challenge. In this work, we have synthesized a PS TPBBT, which incorporates a strong electron-withdrawing unit, benzobisthiadiazole, and four terminal pyridinium groups. It self-assembles into a mixed H/J aggregated state with a maximal absorption peak at 620 nm but coassembles with negatively charged planar small molecules to form sole J-aggregates. Following this strategy, we coassemble TPBBT with rhein, a planar, anionic traditional Chinese medicine with an anticancer activity, which allows for a near 100 nm bathochromic shift of the maximal absorption of TPBBT and improves the photothermal conversion efficiency (PCE) of TPBBT from 6.4 to 60.4% under 808 nm laser irradiation. Additionally, coassembling with TPBBT significantly enhances the cellular uptake of rhein through the photothermal effect. The coassembly of TPBBT and rhein (TPBBTein) can completely eliminate 4T1 tumors on mouse models, validating that this facile strategy not only can tune the NIR J-aggregate of cationic PS through molecular coassembly but also promotes the efficient, symbiotic combination of photothermal therapy and chemotherapy.

Multiscale and stimuli-responsive biosensing in biomedical applications: Emerging biomaterials based on aggregation-induced emission luminogens

Biosensors play a critical role in the diagnosis, treatment, and prognosis of diseases, with diverse applications ranging from molecular diagnostics to in vivo imaging. Conventional fluorescence-based biosensors, however, often suffer from aggregation-caused emission quenching (ACQ), limiting their effectiveness in high concentrations and complex environments. In contrast, the phenomenon of aggregation-induced emission (AIE) has emerged as a promising alternative, where luminescent materials exhibit strong emission in the aggregated state with good photostability, biocompatibility, large Stokes shift, high quantum yield, and tunable emission. This review article discusses the development of AIEgen-based biosensors for multiscale biosensing in biomedical applications. The integration of AIEgens with nanomaterials, such as graphene oxide and stimuli-responsive nanomaterials, can further improve the selectivity and multifunctionality of biomolecule detection. By careful molecular design, the affinity between AIEgens and specific biomolecules can be tuned, enabling the selective detection of targets like DNA, RNA, and proteins ex vivo, in vitro and in vivo, which can be applied across multiple scales, from detecting biomolecules and cellular structures to analyzing tissues and organs, underscoring their growing importance in disease diagnosis. Furthermore, we explore the potential integration of AIEgen-based biosensors with artificial intelligence (AI) technologies, offering promising avenues for future advancements in this field.

6H-Indolo-[2,3-b]-quinoxaline derivatives as promising bifunctional SHP1 inhibitors

Dysfunction in the SHP1 enzyme can cause cancers and many diseases, so it is of great significance to develop novel small molecule SHP1 inhibitors. Through continuous monitoring of metabolic and targeted processes of SHP1 inhibitors in real-time, we can evaluate the effectiveness and toxicity of the inhibitors, further optimize drug design, and explore SHP1 biology. Indoloquinoxaline is an important class of N-containing heterocycle, which has been studied and applied in the pharmacological field and in optoelectronic materials. In this work, the potential Src homology 2 domain-containing phosphatase 1 (SHP1) inhibitor 5a was developed with the help of the structural fusion and scaffold hop of a fluorophore, 6H-indolo-[2,3-b]-quinoxaline, and a bio-active skeleton, thieno[2,3-b]quinoline-procaine. Compound 5a selectively inhibited the SHP1PTP enzyme abilities (IC50 = 2.34 ± 0.06 μM), exhibited a significant fluorescence response (P = 0.007) in response to SHP1PTP activity, and emitted strong blue/green fluorescence in MDA-MB-231 cells. Furthermore, compound 5a showed irreversible binding with SHP1PTP in simulations and dialysis experiments. Altogether, compound 5a serves as a bifunctional SHP1 inhibitor, combining imaging and therapeutic functionalities, enhancing our understanding of SHP1 biological mechanisms, and positively impacting novel drug development.

Modulation of Donor in Purely Organic Triplet Harvesting AIE-TADF Photosensitizer for Image-guided Photodynamic Therapy

Image-guided photodynamic therapy is acknowledged as one of the most demonstrative therapeutic modalities for cancer treatment because of its high precision, non-invasiveness, and improved imaging ability. A series of purely organic photosensitizers denoted as BTMCz, BTMPTZ, and BTMPXZ, have been designed and synthesized and are found to exhibit both thermally activated delayed fluorescence and aggregation-induced emission simultaneously. Experimental and theoretical studies are combined to reveal that modulation of the donor of the photosensitizer enables distinct thermally activated delayed fluorescence via a second-order spin-orbit perturbation mechanism involving lowest singlet charge-transfer and higher-lying triplet locally excited states, respectively. Further, different donor strengths and unique aggregations (H-, J- and X-type packings) greatly influence their color-tunable up-converted luminescence and endow them with superb dispersibility in water. The confocal microscopy-based cellular uptake study confirms the successful internalization of the nano-probes, while BTMCz enables the generation of reactive oxygen species (singlet oxygen) under white-light irradiation, enabling the efficient killing of cancer cells.

Amphiphilic hemicyanine molecular probes crossing the blood-brain barrier for intracranial optical imaging of glioblastoma

Intracranial optical imaging of glioblastoma (GBM) is challenging due to the scarcity of effective probes with blood-brain barrier (BBB) permeability and sufficient imaging depth. Herein, we describe a rational strategy for designing optical probes crossing the BBB based on an electron donor-π-acceptor system to adjust the lipid/water partition coefficient and molecular weight of probes. The amphiphilic hemicyanine dye (namely, IVTPO), which exhibits remarkable optical properties and effective BBB permeability, is chosen as an efficient fluorescence/photoacoustic probe for in vivo real-time imaging of orthotopic GBM with high resolution through the intact skull. Abnormal leakage of IVTPO adjacent to the developing tumor is unambiguously observed at an early stage of tumor development prior to impairment of BBB integrity, as assessed by commercial Evans blue (EB). Compared with EB, IVTPO demonstrates enhanced optical imaging capability and improved tumor-targeting efficacy. These results offer encouraging insights into medical diagnosis of intracranial GBM.

Improvement of growth and lipid accumulation in microalgae with aggregation-induced emission-based nanomaterials towards sustainable lipid production

Microalgae are a hot research area owing to their promising applications for sustainable food, biofunctional compounds, and biofuel feedstock. However, low lipid content in algal biomass is still a challenge that needs to be resolved for commercial use. The current approaches are not satisfactory for achieving high growth and lipid accumulation in algal cells. This research aims to understand and evaluate the effects of light spectral shift on growth and lipid biosynthesis in a green microalga, Chlamydomonas reinhardtii. As a novel approach, an aggregation-induced emission luminogen (AIEgen), TPA-A (C21H19NO), was introduced into the culture media for tailoring the wavelength to a specific range to enhance photosynthesis and lipid production. Algal growth almost doubled at 10 μM TPA-A exposure compared to the control. A significant increase (*p < 0.05) in lipid accumulation was observed in the algal cells exposed to TPA-A. The elevated level of chlorophyll was attributed to fast algal growth. Furthermore, this luminogen was highly biocompatible (∼97% cell viability) on the HaCaT cell line at a concentration of 10 μM in under light conditions. No residues of TPA-A were detected after 7 days in culture media, indicating that this AIEgen was easily degradable. This AIE-based nanomaterial overcomes the conventional fluorophores' aggregation-caused quenching effect by providing increased fluorescence with AIEgen. This approach for lipid induction with increased algal growth provides potential for the algal biofactory to produce sustainable bioproducts and eco-friendly biofuels.

Biomedical applications of the engineered AIEgen-lipid nanostructurein vitroandin vivo

Since the concept of aggregation-induced emission (AIE) was first coined by Tang and co-workers, AIE-active luminogens (AIEgens) have drawn widespread attention among chemists and biologists due to their unique advantages such as high fluorescence efficiency, large Stokes shift, good photostability, low background noise, and high biological visualization capabilities in the aggregated state, surpassing conventional fluorophores. A growing number of AIEgens have been engineered to possess multifunctional properties, including near-infrared emission, two-photon absorption, reactive oxygen species (ROS) generation and photothermal conversion, making them suitable for deep-tissue imaging and phototherapy. AIEgens show great potential in biomedical applicationsin vitroandin vivo. However, despite the favorable photophysical stability and ROS/heat generation capability in the aggregated state, limitations including uncontrolled size, low targeting efficiency, and unexpected dispersion in physiological environments have hindered their biomedical applications. The combination of AIEgens with lipids offers a simple, promising, and widely adopted solution to these challenges. This review article provides an overview of the synthesis methods of AIEgen-lipid nanostructures and their applications in the biomedical engineering field, aiming to serve as a guideline for developing these AIEgens-lipid nanostructures with promising biological applications.

Super-resolution fluorescence imaging of PEDOT:PSS films

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a popular conduction polymer and widely used in organic electronics, bioelectronics and printed electronics. It is believed that PEDOT:PSS has a core-shell colloidal structure dispersed in the formulation. However, the size and surface functional groups of the PEDOT:PSS dispersion and films remain to be visualized. Here, we have introduced the concept of aggregation-induced emission (AIE) to super-resolution imaging for designing the cationic probe TPE-4N+ and accomplished the nanoscale optical visualization of PEDOT:PSS films through reversible electrostatic interactions. Information on the PEDOT:PSS size and surface charge has been successfully collected via super-resolution imaging. The full-width at half-maximum (FWHM) of PSS nanoparticles was observed to be approximately 30-40 nm. The super-resolution fluorescence imaging method can also be used to monitor the PEDOT:PSS film after acid treatment. It was observed that PSS chains were washed away when exposed to concentrated sulfuric acid, which explains why concentrated sulfuric acid treatment greatly improves the conductivity of the PEDOT:PSS film. Super-resolution imaging is promising as an effective method for characterizing PEDOT:PSS films.

Self-Produced O2 CNs-Based Nanocarriers of DNA Hydrophobization Strategy Triggers Photodynamic and Mitochondrial-Derived Ferroptosis for Hepatocellular Carcinoma Combined Treatment

Hypoxia can aggravate tumor occurrence, development, invasion, and metastasis, and greatly inhibit the photodynamic therapy (PDT) effect. Herein, carbon nitride (CNs)-based DNA and photosensitizer co-delivery systems (BPSCNs) with oxygen-producing functions are developed to address this problem. Selenide glucose (Seglu) is used as the dopant to prepare red/NIR-active CNs (SegluCNs). The tumor-targeting unit Bio-PEG2000 is utilized to construct BPSCNs nanoparticles through esterification reactions. Furthermore, DNA hydrophobization is realized via mixing P53 gene with a positively charged mitochondrial-targeted near-infrared (NIR) emitting photosensitizer (MTTPY), which is encapsulated in non-cationic BPSCNs for synergistic delivery. Ester bonds in BPSCNs@MTTPY-P53 complexes can be disrupted by lipase in the liver to facilitate P53 release, upregulated P53 expression, and promoted HIF-1α degradation in mitochondria. In addition, the oxygen produced by the complexes improved the hypoxic microenvironment of hepatocellular carcinoma (HCC), synergistically downregulated HIF-1α expression in mitochondria, promoted mitochondrial-derived ferroptosis and enhanced the PDT effect of the MTTPY unit. Both in vivo and in vitro experiments indicated that the transfected P53-DNA, produced O2 and ROS by these complexes synergistically led to mitochondrial-derived ferroptosis in hepatoma cells through the HIF-1α/SLC7A11 pathway, and completely avoiding PDT resistance caused by hypoxia, exerting a significant therapeutic role in HCC treatment.

The cyano positional isomerism strategy for constructing mitochondria-targeted AIEgens with type I reactive oxygen species generation capability

In this work, a series of cationic luminogens (designated as PSMP isomers) were developed based on the cyano positional isomerism strategy. The isomerism of the cyano substituent on the molecular skeleton can finely regulate the optical behaviour, the type of photoinduced reactive oxygen species (ROS), and mitochondria-targeted capability of isomers. Interestingly, PSMP-4, with the cyano group installed at an appropriate location, exhibits a special aggregation-induced emission effect and potent O2˙- generation efficacy through the type I photochemistry pathway. Notably, PSMP-4 can accumulate in mitochondria with high specificity. Taking advantage of its excellent photostability, PSMP-4 realizes in situ mitochondria imaging in a washing-free manner and sensitive response to the change of mitochondrial membrane potential. The integration of comprehensive photophysical properties and mitochondrial specificity enable PSMP-4 to successfully trigger the death of cancer cells through an efficient type I photodynamic therapy process both in vitro and in multicellular tumor spheroid models.

Three-in-One: Molecular Engineering of D-A-π-A Featured Type I and Type II Near-Infrared AIE Photosensitizers for Efficient Photodynamic Cancer Therapy and Bacteria Killing

Bacterial infections are closely correlated with the genesis and progression of cancer, and the elimination of cancer-related bacteria may improve the efficacy of cancer treatment. However, the combinatorial therapy that utilizes two or more chemodrugs will increase potential adverse effects. Image-guided photodynamic therapy is a highly precise and potential therapy to treat tumor and microbial infections. Herein, four donor-acceptor-π-bridge-acceptor (D-A-π-A) featured near-infrared (NIR) aggregation-induced emission luminogens (AIEgens) (TQTPy, TPQTPy, TQTC, and TPQTC) with type I and type II reaction oxygen species (ROS) generation capabilities are synthesized. Notably, TQTPy shows mitochondria targeted capacity, the best ROS production efficiency, long-term tumor retention capacity, and more importantly, the three-in-one fluorescence imaging guided therapy against both tumor and microbial infections. Both in vitro and in vivo results validate that TQTPy performs well in practical biomedical application in terms of NIR-fluorescence imaging-guided photodynamic cancer diagnosis and treatment. Moreover, the amphiphilic and positively charged TQTPy is able to specific and ultrafast discrimination and elimination of Gram-positive (G+) Staphylococcus aureus from Gram-negative (G-) Escherichia coli and normal cells. This investigation provides an instructive way for the construction of three-in-one treatment for image-guided photodynamic cancer therapy and bacteria elimination.

Dual-/multi-organelle-targeted AIE probes associated with oxidative stress for biomedical applications

In situ monitoring of biological processes between different organelles upon oxidative stress is one of the most important research hotspots. Fluorescence imaging is especially suitable for biomedical applications due to its distinct advantages of high spatiotemporal resolution, high sensitivity, non-invasiveness, and in situ monitoring capabilities. However, most fluorescent probes can only achieve light-up imaging of single organelles, thus the combined use of two or more probes is usually required for monitoring biological processes between organelles, which can suffer from tedious staining and washing procedures, increased cytotoxicity and poor photostability. Exogenetic oxidants can affect broad-spectrum subcellular organelles, which are not conducive to in situ monitoring of biological processes between specific organelles. To tackle these challenges, a series of dual-/multi-organelle-targeted aggregation-induced emission (AIE) probes associated with oxidative stress have been designed and developed in the past few years. Herein, the recent progress of these AIE probes is summarized in biomedical applications, such as apoptosis monitoring, interplay between organelles, microenvironmental changes of organelles, organelle morphology tracking, precise cancer therapy, and so forth. Moreover, the further outlook for dual-/multi-organelle-targeted AIE probes is discussed, aiming to promote innovative research in biomedical applications.

Strategically engineered Au(I) complexes for orchestrated tumor eradication via chemo-phototherapy and induced immunogenic cell death

Cancer is a significant cause of death around the world, and for many varieties, treatment is not successful. Therefore, there is a need for the development of innovative, efficacious, and precisely targeted treatments. Here, we develop a series of Au(I) complexes (1-4) through rational manipulation of ligand structures, thereby achieving tumor cell specific targeting and orchestrated tumor eradication via chemo-phototherapy and induced immunogenic cell death. A comprehensive exploration based on in vitro and in vivo female mice experimentation shows that complex 4 exhibits proficiency in specific tumor imaging, endoplasmic reticulum targeting, and has robust therapeutic capabilities. Mechanistic elucidation indicates that the anticancer effect derives from the synergistic actions of thioredoxin reductase inhibition, highly efficient reactive oxygen species production and immunogenic cell death. This work presents a report on a robust Au(I) complex integrating three therapeutic modalities within a singular system. The strategy presented in this work provides a valuable reference for the development of high-performance therapeutic agents.

Engineering photodynamics for treatment, priming and imaging

Photodynamic therapy (PDT) is a photochemistry-based treatment approach that relies on the activation of photosensitizers by light to locally generate reactive oxygen species that induce cellular cytotoxicity, in particular for the treatment of tumours. The cytotoxic effects of PDT are depth-limited owing to light penetration limits in tissue. However, photodynamic priming (PDP), which inherently occurs during PDT, can prime the tissue microenvironment to adjuvant therapies beyond the direct PDT ablative zone. In this Review, we discuss the underlying mechanisms of PDT and PDP, and their application to the treatment of cancer, outlining how PDP can permeabilize the tumour vasculature, overcome biological barriers, modulate multidrug resistance, enhance immune responses, increase tumour permeability and enable the photochemical release of drugs. We further examine the molecular engineering of photosensitizers to improve their pharmacodynamic and pharmacokinetic properties, increase their molecular specificity and allow image guidance of PDT, and investigate engineered cellular models for the design and optimization of PDT and PDP. Finally, we discuss alternative activation sources, including ultrasound, X-rays and self-illuminating compounds, and outline key barriers to the clinical translation of PDT and PDP.

A universal strategy for constructing high-performance silica-based AIE materials for biomedical application

As an emerging fluorophore, aggregation-induced emission luminogens (AIEgens) have received widespread attention in recent years, but the inherent drawbacks of AIEgens, such as the poor water-solubility and insufficient fluorescence stability in complex environments, restrict their performance in practical applications. Herein, we report a universal strategy based on hydrophobic dendritic mesoporous silica (HMSN) that can integrate different AIE molecules to construct multi-color fluorescent AIE materials. Specifically, HMSN with central radial pores was used as a powerful carrier for direct loading AIE molecules and restricting their intramolecular motions. Due to the pore-domain restriction effect and hydrophobic interaction, the obtained silica-based AIE materials have bright fluorescence with a maximum quantum yield of 68.38%, high colloidal/fluorescence stability, and excellent biosafety. Further, these silica-based AIE materials can be conjugated with functional antibodies to obtain probes with different targetability. After integration with immunomagnetic beads, the prepared detection probes achieved the quantitative detection of cardiac troponin I with the limit of detection (LOD) of 0.508 ng/mL. Overall, the targeting probes stemming from silica-based AIE materials can not only achieve cell-specific imaging, but quantify the number of Jurkat cells (LOD = 270 cells/mL) to further determine the specific etiology of the disease.

Far-infrared radiation and its therapeutic parameters: A superior alternative for future regenerative medicine?

In future regenerative medicine, far-infrared radiation (FIR) may be an essential component of optical therapy. Many studies have confirmed or validated the efficacy and safety of FIR in various diseases, benefiting from new insights into FIR mechanisms and the excellent performance of many applications. However, the lack of consensus on the biological effects and therapeutic parameters of FIR limits its practical applications in the clinic. In this review, the definition, characteristics, and underlying principles of the FIR are systematically illustrated. We outline the therapeutic parameters of FIR, including the wavelength range, power density, irradiation time, and distance. In addition, the biological effects, potential molecular mechanisms, and preclinical and clinical applications of FIR are discussed. Furthermore, the future development and applications of FIR are described in this review. By applying optimal therapeutic parameters, FIR can influence various cells, animal models, and patients, eliciting diverse underlying mechanisms and offering therapeutic potential for many diseases. FIR could represent a superior alternative with broad prospects for application in future regenerative medicine.

Recent progress in hydrogels combined with phototherapy for bacterial infection: A review

Phototherapy has become one of the most effective antibacterial methods due to its associated lack of drug resistance and its good antibacterial effect. For the purpose of avoiding the aggregation and premature release of photosensitive/photothermal agents during phototherapy, they can be mixed into three-dimensional hydrogels. The combination of hydrogels and phototherapy combines the merits of both hydrogels and phototherapy, overcomes the disadvantages of traditional antibacterial methodologies, and has broad application prospects. This review presents recent advancements in phototherapeutic antibacterial hydrogels including photodynamic antibacterial hydrogels, photothermal antibacterial hydrogels, photodynamic and photothermal synergistic antibacterial hydrogels, and other synergistic antibacterial hydrogels involving phototherapy.

Fluorescent styrenes for mitochondrial imaging and viscosity sensing

Fluorophores bearing cationic pendants, such as the pyridinium group, tend to preferentially accumulate in mitochondria, whereas those with pentafluorophenyl groups display a distinct affinity for the endoplasmic reticulum. In this study, we designed fluorophores incorporating pyridinium and pentafluorophenyl pendants and examined their impact on sub-cellular localization. Remarkably, the fluorophores exhibited a notable propensity for the mitochondrial membrane. Furthermore, these fluorophores revealed dual functionality by facilitating the detection of viscosity changes within the sub-cellular environment and serving as heavy-atom-free photosensitizers. With easy chemical tunability, wash-free imaging, and a favorable signal-to-noise ratio, these fluorophores are valuable tools for imaging mitochondria and investigating their cellular processes.

Synthesis, Fluorescence, and Bioactivity of Novel Isatin Derivatives

The isatin group is widespread in nature and is considered to be a privileged building block for drug discovery. In order to develop novel SHP1 inhibitors with fluorescent properties as tools for SHP1 biology research, this work designed and synthesized a series of isatin derivatives. The presentive compound 5a showed good inhibitory activity against SHP1PTP with IC50 of 11 ± 3 μM, displayed about 92% inhibitory rate against MV-4-11 cell proliferation at the concentration of 20 μM, exhibited suitable fluorescent properties with a long emission wavelength and a large Stokes shift, and presented blue fluorescent imaging in HeLa cells with low cytotoxicity. This study could offer chemical tool to further understand SHP1 biology and develop novel SHP1 inhibitors in therapy.

Sulphur-atom positional engineering in perylenimide: structure-property relationships and H-aggregation directed type-I photodynamic therapy

An innovative design strategy of placing sulfur (S)-atoms within the pendant functional groups and at carbonyl positions in conventional perylenimide (PNI-O) has been demonstrated to investigate the condensed state structure-property relationship and potential photodynamic therapy (PDT) application. Incorporation of simply S-atoms at the peri-functionalized perylenimide (RPNI-O) leads to an aggregation-induced enhanced emission luminogen (AIEEgen), 2-hexyl-8-(thianthren-1-yl)-1H-benzo[5,10]anthra[2,1,9-def]isoquinoline-1,3(2H)-dione (API), which achieves a remarkable photoluminescence quantum yield (Φ PL) of 0.85 in aqueous environments and established novel AIE mechanisms. Additionally, substitution of the S-atom at the carbonyl position in RPNI-O leads to thioperylenimides (RPNI-S): 2-hexyl-8-phenyl-1H-benzo[5,10]anthra[2,1,9-def]isoquinoline-1,3(2H)-dithione (PPIS), 8-([2,2'-bithiophen]-5-yl)-2-hexyl-1H-benzo[5,10]anthra[2,1,9-def]isoquinoline-1,3(2H)-dithione (THPIS), and 2-hexyl-8-(thianthren-1-yl)-1H-benzo[5,10]anthra[2,1,9-def]isoquinoline-1,3(2H)-dithion (APIS), with distinct photophysical properties (enlarged spin-orbit coupling (SOC) and Φ PL ≈ 0.00), and developed diverse potent photosensitizers (PSs). The present work provides a novel SOC enhancement mechanism via pronounced H-aggregation. Surprisingly, the lowest singlet oxygen quantum yield (Φ Δ) and theoretical calculation suggest the specific type-I PDT for RPNI-S. Interestingly, RPNI-S efficiently produces superoxide (O2˙-) due to its remarkably lower Gibbs free energy (ΔG) values (THPIS: -40.83 kcal mol-1). The non-toxic and heavy-atom free very specific thio-based PPIS and THPIS PSs showed selective and efficient PDT under normoxia, as a rare example.

One Stone, Two Birds: High-Brightness Aggregation-Induced Emission Photosensitizers for Super-Resolution Imaging and Photodynamic Therapy

Most aggregation-induced emission (AIE) luminogens exhibit high brightness, excellent photostability, and good biocompatibility, but these AIE-active agents, which kill two birds with one stone to result in applications in both stimulated emission depletion (STED) super-resolution imaging and photodynamic therapy (PDT), have not been reported yet but are urgently needed. To meet the requirements of STED nanoscopy and PDT, D-A-π-A-D type DTPABT-HP is designed by tuning conjugated π spacers. It exhibits red-shifted emission, high PLQY of 32.04%, and impressive 1O2 generation (9.24 fold compared to RB) in nanoparticles (NPs). Then, DTPABT-HP NPs are applied in cell imaging via STED nanoscopy, especially visualizing the dynamic changes of lysosomes in the PDT process at ultrahigh resolution. After that, in vivo PDT was also conducted by DTPABT-HP NPs, resulting in significantly inhibited tumor growth, with an inhibition rate of 86%. The work here is beneficial to the design of multifunctional agents and the deep understanding of their phototheranostic mechanism in biological research.

In Situ-Grown 2D Perovskite Based on π-Conjugated Aggregation-Induced Emission Organic Spacer Boosting the Efficiency and Stability of 2D-3D Heterostructured Perovskite Solar Cells

The two-dimensional-three-dimensional (2D-3D) heterostructured perovskite solar cells (PSCs) have drawn widespread interest, wherein the organic spacer plays a significant role in the photovoltaic performance. Herein, a novel π-conjugated organic spacer with the aggregation-induced emission (AIE) property, (Z)-2-([1,1'-biphenyl]-4-yl)-3-(5-(4-(3-aminopropoxy)phenyl)thiophen-2-yl)acrylonitrile (BPCSA-S), is designed and synthesized, which is successfully applied for the in situ construction of 2D-3D heterostructured PSCs via the two-step solution method. By virtue of the functional groups (i.e., cyano, thiophene, and amino) in BPCSA-S, the BPCSA-S organic spacer can trigger the in situ growth of 2D perovskites, which will serve as the template for the heteroepitaxial growth of 3D perovskites, thus obtaining a 2D-3D heterostructured film with high-quality and few defects. More pleasingly, benefiting from the AIE property and delocalized π-electrons in the π-conjugated BPCSA-S organic spacer, excellent photosensitization process and carrier transport can be achieved. Consequently, the resultant 2D-3D heterostructured PSCs yield a pleasing PCE of 22.07%, accompanied by mitigatory hysteresis, as well as enhanced stability. Our research shows a hopeful multifunctional organic spacer approach using the novel π-conjugated AIE organic spacer for high-performance PSCs.

Mitochondria-Associated Transcriptome Profiling via Localizable Aggregation-Induced Emission Photosensitizers in Live Cells

In recent decades, there has been increasing interest in studying mitochondria through transcriptomic research. Various exogenous fusion protein-based proximity labeling methods have been reported that focus on the site of one particular protein/peptide and might also influence the corresponding localization or interactome. To enable unbiased and high spatial-resolution profiling of mitochondria-associated transcriptomes in live cells, a flexible RNA proximity labeling approach was developed using aggregation-induced emission (AIE) type photosensitizers (PSs) that possess great mitochondria-targeting capabilities. Their accumulation in an enclosed mitochondrial environment tends to enhance the fluorescence emission and reactive oxygen species generation. By comparing the in vitro optical properties, photosensitization processes, as well as the in cellulo mitochondrial specificity and RNA labeling performance of four AIE PSs, high-throughput sequencing analysis was conducted using TFPy-mediated RNA proximity labeling in live HeLa cells. This approach successfully captured a comprehensive list of transcripts, including mitochondria-encoded RNAs, as well as some nuclear-derived RNAs located at the outer mitochondrial membrane and interacting organelles. This small molecule-based proximity labeling method bypasses complex genetic manipulation and transfection steps, making it readily applicable for diverse research purposes.

Reviewing the evolutive ACQ-to-AIE transformation of photosensitizers for phototheranostics

Photodynamic therapy (PDT) represents an emerging noninvasive treatment technique for cancers and various nonmalignant diseases, including infections. During the process of PDT, the physical and chemical properties of photosensitizers (PSs) critically determine the effectiveness of PDT. Traditional PSs have made great progress in clinical applications. One of the challenges is that traditional PSs suffer from aggregation-caused quenching (ACQ) due to their discotic structures. Recently, aggregation-induced emission PSs (AIE-PSs) with a twisted propeller-shaped conformation have been widely concerned because of high reactive oxygen species (ROS) generation efficiency, strong fluorescence efficiency, and resistance to photobleaching. However, AIE-PSs also have some disadvantages, such as short absorption wavelengths and insufficient molar absorption coefficient. When the advantages and disadvantages of AIE-PSs and ACQ-PSs are complementary, combining ACQ-PSs and AIE-PSs is a "win-to-win" strategy. As far as we know, the conversion of traditional representative ACQ-PSs to AIE-PSs for phototheranostics has not been reviewed. In the review, we summarize the recent progress on the ACQ-to-AIE transformation of PSs and the strategies to achieve desirable theranostic applications. The review would be helpful to design more efficient ACQ-AIE-PSs in the future and to accelerate the development and clinical application of PDT.

AIEgens Cross-linked Iron Oxide Nanoparticles Synchronously Amplify Bimodal Imaging Signals in Situ by Tumor Acidity-Mediated Click Reaction

Activatable dual-modal molecular imaging probes present a promising tool for the diagnosis of malignant tumors. However, synchronously enhancing dual-modal imaging signals under a single stimulus is challenging. Herein, we propose an activatable bimodal probe that integrates aggregation-induced emission luminogens (AIEgens) and iron oxide nanoparticles (IOs) to synergistically enhance near-infrared fluorescence (NIRF) intensity and magnetic resonance (MR) contrast through a tumor acidity-mediated click reaction. Tumor acidity-responsive IOs containing dibenzocyclooctyne groups (termed cDIOs) and AIEgens containing azide groups (termed AATs) can be covalently cross-linked in response to tumor acidity, which leads to a simultaneous enhancement in NIRF intensity (≈12.4-fold) and r2 relaxivity (≈2.8-fold). cDIOs and AATs were effectively activated in mice orthotropic breast tumor, and the cross-linking prolonged their retention in tumor, further augmenting the bimodal signals and expanding imaging time frame. This facile strategy leverages the inherent properties of probes themselves and demonstrates promise in future translational studies.

Host-Guest Photosensitizer of a Cationic BODIPY Derivative and Cucurbit[7]uril for High-Efficiency Visible Light-Induced Photooxidation Reactions

In recent years, there has been a notable surge of interest in the fields of organic and pharmaceutical research about photocatalysts (PCs) and photosensitizers (PSs). In this study, a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) molecule adorned with quaternary ammonium (TMB) functionality was meticulously designed and synthesized. This compound has remarkable characteristics such as exceptional water solubility, great optical qualities, and commendable photostability. It can form a 1:1 complex (TMB-CB[7]) with cucurbit[7]uril (CB[7]) through host-guest interactions in the aqueous solution and shows obvious fluorescence enhancement. The reactive oxygen species (ROS) including superoxide anion radical (O2·-) and singlet oxygen (1O2) generation ability of TMB-CB[7] were promoted compared with that of TMB in the aqueous solution. More interestingly, the ROS generated from TMB-CB[7] can be used as PCs for aerobic cross dehydrogenation coupling reactions and photooxidation reactions in water with high yields of 89 and 95%, respectively. Therefore, the utilization of a host-guest PS presents a novel and environmentally friendly approach for conducting photocatalyzed organic processes under ambient conditions using visible light.

A turn-on fluorescent probe for lipid-targeting imaging in human arterial aneurysm and fibrocalcific stenotic aortic valve

Fluorescence imaging techniques have shown remarkable performance in studying the biological functions of lipid droplets (LDs). However, the biological applications of the commercially available LDs probes suffer from insufficient specificity and low signal/noise ratio (SNR). Herein, we presented a novel near-infrared (NIR) lipid activatable fluorescence probe, namely Me2NND, with extremely low emission in water but significantly enhanced emission in the lipid environment. Me2NND presented good biocompatibility and impressive LDs-specific imaging ability in cells and tissues. Moreover, Me2NND has also shown good photostability and it could efficiently locate the distribution of LDs in human pathological samples of aortic aneurysms and fibrocalcific stenotic aortic valves. This study provided a novel turn-on probe Me2NND and would improve the bio-applications of LDs-specific probes.

Clinically Translatable Solid-State Dye for NIR-II Imaging of Medical Devices

Medical devices are commonly implanted underneath the skin, but how to real-time noninvasively monitor their migration, integrity, and biodegradation in human body is still a formidable challenge. Here, the study demonstrates that benzyl violet 4B (BV-4B), a main component in the FDA-approved surgical suture, is found to produce fluorescence signal in the first near-infrared window (NIR-I, 700-900 nm) in polar solutions, whereas BV-4B self-assembles into highly crystalline aggregates upon a formation of ultrasmall nanodots and can emit strong fluorescence in the second near-infrared window (NIR-II, 1000-1700 nm) with a dramatic bathochromic shift in the absorption spectrum of ≈200 nm. Intriguingly, BV-4B-involved suture knots underneath the skin can be facilely monitored during the whole degradation process in vivo, and the rupture of the customized BV-4B-coated silicone catheter is noninvasively diagnosed by NIR-II imaging. Furthermore, BV-4B suspended in embolization glue achieves hybrid fluorescence-guided surgery (hybrid FGS) for arteriovenous malformation. As a proof-of-concept study, the solid-state BV-4B is successfully used for NIR-II imaging of surgical sutures in operations of patients. Overall, as a clinically translatable solid-state dye, BV-4B can be applied for in vivo monitoring the fate of medical devices by NIR-II imaging.

Seeing is believing: Efficiency evaluation of multifunctional ionic-dependent AIEgens for tuberculosis

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a significant public health threat with high rates of infection and mortality. Rapid and reliable theranostics of TB are essential to control transmission and shorten treatment duration. In this study, we report two cationic aggregation-inducing emission luminogens (AIEgens) named TTVP and TTPy, which have different functional charged moieties, to investigate their potential for simultaneous tracing and photodynamic therapy in TB infection. TTVP and TTPy exhibit intrinsic positive charges, excellent water solubility, and near-infrared (NIR) emission. Based on ionic-function relationships, TTVP, with more positive charges, demonstrates a stronger binding affinity to Mycobacterium marinum (M.m), (a close genetic relative of Mtb), compared to TTPy. Both TTVP and TTPy exhibit high efficiency in generating reactive oxygen species (ROS) when exposed to white light irradiation, enabling effective photodynamic killing of M.m in vitro. Additionally, we achieved long-term, real-time, noninvasive, continuous tracing, and evaluated therapeutic performance in vivo. Notably, TTVP outperformed TTPy in intracellular killing of M.m, suggesting a possible correlation between the labeling and photodynamic killing abilities of AIEgens. These findings provide valuable insights and a design basis for cationic AIEgens in TB research, offering potential advancements in TB theranostics.

Endoplasmic Reticulum-Targeted Aggregation-Induced Emission Luminogen for Synergetic Tumor Ablation with Glibenclamide

Photodynamic therapy based on fluorescence illumination of subcellular organelles and in situ bursts of reactive oxygen species (ROS) has been recognized as a promising strategy for cancer theranostics. However, the short life of ROS and unclarified anticancer mechanism seriously restrict the application. Herein, we rationally designed and facilely synthesized a 2,6-dimethylpyridine-based triphenylamine (TPA) derivative TPA-DMPy with aggregation-induced emission (AIE) features and production of type-I ROS. Except for its selective binding to the endoplasmic reticulum (ER), TPA-DMPy, in synergy with glibenclamide, a medicinal agent used against diabetes, induced significant apoptosis of cancer cells in vitro and in vivo. Additionally, TPA-DMPy greatly incited the release of calcium from ER upon light irradiation to further aggravate the depolarization of ER membrane potential caused by glibenclamide, thus inducing fatal ER stress and crosstalk between ER and mitochondria. Our study extends the biological design and application of AIE luminogens and provides new insights into discovering novel anticancer targets and agents.

Pyrene-Based Cationic Fluorophores with High Affinity for BF4-, PF6-, and ClO4- Anions: Detection and Removal

Anions play an indispensable role in the balance and regulation of the ecological environment and human health; however, excess anions can cause serious ecological and environment problems. Therefore, the detection and removal of excess anions in aqueous solution is not only a technological problem but also crucial for environmental protection. Herein, a set of water-soluble pyrene-based cationic fluorophores were synthesized, which exhibit high sensitivity for the detection of the anions BF4-, PF6-, and ClO4- via electrostatic interactions. Such fluorescent probes exhibit "turn-on" emission characteristics even at low concentrations of anions due to anion-π+ interactions. Moreover, these fluorescence probes act as efficient precipitating agents for the removal of the BF4-, PF6-, and ClO4- anions from an aqueous environment. This work opens up new avenues for future research on pyrene-based fluorophores as turn-on fluorescence probes for anion detection and as excellent precipitating agents in environmental settings.

Tyrosinase-activated Nanocomposites for Double-Modals Imaging Guided Photodynamic and Photothermal Synergistic Therapy

Tyrosinase (TYR) is an important biomarker of melanoma. The exploration of fluorescent pr-obes-based composites is beneficial to build an integrative platform for the diagnosis and treatment of melanoma. Herein, a multifunctional nanocomposite IOBOH@BSA activated by TYR is developed for selective imaging and ablation of melanoma. The chemical structure of IOBOH enables the fluorescence (FL) imaging activated by TYR, photoacoustic (PA) imaging, and photodynamic-photothermal activity by regulating the balance between radiative decay and non-radiative decay. IOBOH combined with bovine serum albumin (IOBOH@BSA) presents the response to TYR and realizes FL imaging with mitochondria-targeting in melanoma. Moreover, IOBOH@BSA shows excellent photothermal ability and is applied for PA imaging. After IOBOH@BSA is activated by TYR, the singlet oxygen generation increases obviously. IOBOH@BSA can realize TYR-activated imaging and photodynamic-photothermal therapy of melanoma. The development of TYR-activated multifunctional nanocomposites promotes the precise imaging and improves the therapeutic effect of melanoma.

Aggregation-induced type I&II photosensitivity and photodegradability-based molecular backbones for synergistic antibacterial and cancer phototherapy via photodynamic and photothermal therapies

The clinical applications of phototherapy nanomaterials are still limited due to concerns regarding their phototoxicity and efficacy. Herein, we report a novel type of D-π-A molecular backbone that induces type I/II photosensitivity and photodegradability by forming J-aggregates. The photodegradation rate can be regulated by changing the donor groups to regulate the photosensitivity of their aggregates because the photodegradability performance results from their oxidation by 1O2 generated by their type II photosensitivity. AID4 NPs possess faster photodegradation because of their better type I&II photosensitivity, which can also self-regulate by inhibiting type II and improving type I under hypoxic conditions. Moreover, they exhibited good photothermal and photoacoustic performance for improving their therapeutic effect by a synergistic effect and achieving photoacoustic imaging in vivo. The experimental result also showed that they can be effective for antibacterial and anti-tumor treatment and the photodegradation products of AID4 NPs possess low biological toxicity in the dark or under light. This study could provide a novel strategy for improving the safety and treatment effects of phototherapy.

A Highly Water-Soluble Aggregation-Induced Emission Luminogen with Anion-π+ Interactions for Targeted NIR Imaging of Cancer Cells and Type I Photodynamic Therapy

The low oxygen dependence of type I photosensitizers (PSs) has made them a popular choice for treating solid tumors. However, the drawbacks of poor water solubility, short emission wavelength, poor stability, and inability to distinguish cancer cells from normal cells limit the application of most type I PSs in clinical therapy. Thereby, developing novel type I PSs for overcoming these problems is an urgent but challenging task. Herein, by utilizing the distinctive structural characteristics of anion-π+ interactions, a highly water-soluble type I PS (DPBC-Br) with aggregation-induced emission (AIE) characteristic and near-infrared (NIR) emission is fabricated for the first time. DPBC-Br displays remarkable water solubility (7.3 mM) and outstanding photobleaching resistance, enabling efficient and precise differentiation between tumor cells and normal cells in a wash-free and long-term tracking manner via NIR-I imaging. Additionally, the superior type I reactive oxygen species (ROS) produced by DPBC-Br provide both specific killing of cancer cells in vitro and inhibition of tumor growth in vivo, with negligible systemic toxicity. This study rationally constructs a highly water-soluble type I PS, which has higher reliability and controllability compared with conventional nanoparticle formulating procedures, offering great potential for clinical cancer treatment.

Photoactivatable Sequential Destruction of Multiorganelles for Cancer Therapy

Organelle-targeted therapy guided by fluorescence imaging is promising for precise cancer treatment. However, most current organelle-targeted therapeutics can only destruct single organelles, which suffer from limited therapeutic efficacy. To address this challenge, a photoactivatable probe was developed for sequential photodynamic destruction of multiorganelles in cancer cells, including lysosomes, lipid droplets, and mitochondria. This photoactivatable probe not only exhibits efficient cancer cell eradication in vitro but also can suppress tumor growth in vivo. Simultaneously, the photoactivatable probe enables sequential destruction of multiple organelles in cancer cells, which can be observed in situ through the conversion of green-to-red fluorescence facilitated by a photooxidative dehydrogenation reaction. We believe this photoactivatable probe for sequential destruction of multiple organelles associated with fluorescence color conversion provides a new strategy for cancer treatment with greatly improved efficacy.

Visual Multifunctional Aggregation-Induced Emission-Based Bacterial Cellulose for Killing of Multidrug-Resistant Bacteria

Multidrug-resistant (MDR) bacteria-related wound infections are a thorny issue. It is urgent to develop new antibacterial wound dressings that can not only prevent wounds from MDR bacteria infection but also promote wound healing. Herein, an aggregation-induced emission (AIE) molecule BITT-composited bacterial cellulose (BC) is presented as wound dressings. BC-BITT composites have good transparency, making it easy to monitor the wound healing process through the composite membrane. The BC-BITT composites retain the advantages of biocompatible BC, and display photodynamic and photothermal synergistic antibacterial effects under irradiation of a 660 nm laser. Furthermore, the BC-BITT composites show excellent wound healing performance in a mouse full-thickness skin wound model infected by MDR bacteria, simultaneously with negligible toxicity. This work paves a way for treating clinically troublesome wound infections.

Rational design of water-soluble mitochondrial-targeting near-infrared fluorescent probes with large Stokes shift for distinguishing cancerous cells and bioimaging

In the paper, two new near-infrared fluorescent probes (TTHPs) with D-π-A structure were successfully synthesized. TTHPs exhibited polarity and viscosity sensitivity and mitochondrial targeting under physiological conditions. The emission spectra of TTHPs showed strong polarity/viscosity dependence with more than a large Stokes shift of 200 nm. Based on their unique merits, TTHPs were used to distinguish cancerous and normal cells, which could be new tools for cancer diagnosis. Moreover, TTHPs were the first to achieve biological imaging of Caenorhabditis elegans, which could be labeling probes to apply in multicellular organisms.

Recent advances in type I organic photosensitizers for efficient photodynamic therapy for overcoming tumor hypoxia

Photodynamic therapy (PDT) with an oxygen-dependent character is a noninvasive therapeutic method for cancer treatment. However, its clinical therapeutic effect is greatly restricted by tumor hypoxia. What's more, both PDT-mediated oxygen consumption and microvascular damage aggravate tumor hypoxia, thus, further impeding therapeutic outcomes. Compared to type II PDT with high oxygen dependence and high oxygen consumption, type I PDT with less oxygen consumption exhibits great potential to overcome the vicious hypoxic plight in solid tumors. Type I photosensitizers (PSs) are significantly important for determining the therapeutic efficacy of PDT, which performs an electron transfer photochemical reaction with the surrounding oxygen/substrates to generate highly cytotoxic free radicals such as superoxide radicals (˙O₂^-) as type I ROS. In particular, the primary precursor (˙O₂^-) would progressively undergo a superoxide dismutase (SOD)-mediated disproportionation reaction and a Haber-Weiss/Fenton reaction, yielding higher cytotoxic species (˙OH) with better anticancer effects. As a result, developing high-performance type I PSs to treat hypoxic tumors has become more and more important and urgent. Herein, the latest progress of organic type I PSs (such as AIE-active cationic/neutral PSs, cationic/neutral PSs, polymer-based PSs and supramolecular self-assembled PSs) for monotherapy or synergistic therapeutic modalities is summarized. The molecular design principles and strategies (donor-acceptor system, anion-π⁺ incorporation, polymerization and cationization) are highlighted. Furthermore, the future challenges and prospects of type I PSs in hypoxia-overcoming PDT are proposed.

Aggregation-induced bioprobe for plasma membrane-specific imaging and photodynamic cancer cell ablation

Selective labelling of the plasma membrane (PM) by fluorescence imaging techniques enables an intuitive analysis of cell status together with dynamic changes, and therefore is of great value. We herein disclose a novel carbazole-based probe, CPPPy, that shows aggregation-induced emission (AIE) property and is observed to selectively accumulate at the PM of living cells. Benefiting from its good biocompatibility and PM-targeted specificity, CPPPy can light up the PM of cells by high-resolution imaging even at a low concentration of 200 nM. Simultaneously, CPPPy is capable of generating both singlet oxygen and free radical-dominated species upon visible light irradiation, which further induces irreversible growth inhibition and necrocytosis of tumor cells. This study thus provides new insight into the construction of multifunctional fluorescence probes with PM-specific bioimaging and photodynamic therapy.

Ultra-Small Nano-Assemblies as Tumor-Targeted and Renal Clearable Theranostic Agent for Photodynamic Therapy

It is a challenge to design photosensitizers to balance between the tumor-targeting enrichment for precise treatment and efficient clearance within a reasonable timescale for reducing side effects. Herein, an ultra-small nano-photosensitizer 1a with excellent tumor-specific accumulation and renal clearance is reported. It is formed from the self-assembly of compound 1 bearing three triethylene glycol (TEG) arms and two pyridinium groups in water. The positively charged surface with neutral TEG coating enables 1a to efficiently target the tumor, with the signal-to-background ratio reaching as high as 11.5 after tail intravenous injection. The ultra-small size of 1a with an average diameter of 5.6 nm allows its fast clearance through kidney. Self-assembly also endows 1a with an 18.2-fold enhancement of reactive oxygygen species generation rate compared to compound 1 in organic solution. Nano-PS 1a manifests an excellent photodynamic therapy efficacy on tumor-bearing mouse models. This work provides a promising design strategy of photosensitizers with renal clearable and tumor-targeting ability.

Dynamic and Reversible Decoration of DNA-Based Scaffolds

An approach to achieving dynamic and reversible decoration of DNA-based scaffolds is demonstrated here. To do this, rationally engineered DNA tiles containing enzyme-responsive strands covalently conjugated to different molecular labels are employed. These strands are designed to be recognized and degraded by specific enzymes (i.e., Ribonuclease H, RNase H, or Uracil DNA Glycosylase, UDG) inducing their spontaneous de-hybridization from the assembled tile and replacement by a new strand conjugated to a different label. Multiple enzyme-responsive strands that specifically respond to different enzymes allow for dynamic, orthogonal, and reversible decoration of the DNA structures. As a proof-of-principle of the strategy, the possibility to orthogonally control the distribution of different labels (i.e., fluorophores and small molecules) on the same scaffold without crosstalk is demonstrated. By doing so, DNA scaffolds that display different antibody recognition patterns are obtained. The approach offers the possibility to control the decoration of higher-order supramolecular assemblies (including origami) with several functional moieties to achieve functional biomaterials with improved adaptability, precision, and sensing capabilities.

Photosensitizer-based small molecule theranostic agents for tumor-targeted monitoring and phototherapy

Small molecule theranostic agents for tumor treatment exhibited triadic properties in tumor targeting, imaging, and therapy, which have attracted increasing attention as a potential complement for, or improved to, classical small molecule antitumor drugs. Photosensitizer have dual functions of imaging and phototherapy, and have been widely used in the construction of small molecule theranostic agents over the last decade. In this review, we summarized representative agents that have been studied in the field of small molecule theranostic agents based on photosensitizer in the last decade, and highlighted their characteristics and application in tumor-targeted monitoring and phototherapy. The challenges and future perspectives of photosensitizers in building small molecule theranostic agents for diagnosis and therapy of tumors were also discussed.

Mitochondria Targeted AIE Probes for Cancer Phototherapy

In recent years, mitochondrion (powerhouse of the cells) gained lots of interest as one of the unorthodox targets for futuristic cancer therapy. As a result, novel small molecules were developed to damage and image mitochondria in cancer models. In this context, aggregation-induced emission probes (AIEgens) received immense attention due to their applications in mitochondria-targeted biosensing, imaging, and biomedical theranostics. On the other hand, phototherapy (photodynamic and photothermal) has emerged as a powerful alternative to manage cancer due to its less invasive nature. However, merging these two areas to engineer mitochondria-targeted phototherapeutic probes for cancer diagnosis and treatment has remained a major challenge. In this mini-review, we will outline the development of novel mitochondria-targeted small molecule AIEgens as imaging agents and photosensitizers for photodynamic therapy along with dual photodymanic-phototheramal therapy and chemo-photodynamic therapy. We will also highlight the current challenges in developing mitochondria-targeted photothermal therapy probes for future biomedical theranostic applications to manage cancer.

As Fiber Meets with AIE: Opening a Wonderland for Smart Flexible Materials

Aggregation-induced emission luminogens (AIEgens) have recently been developed at a tremendous pace in the area of organic luminescent materials by virtue of their superior properties. However, the practical applications of AIEgens still face the challenge of transforming AIEgens from molecules into materials. Till now, many AIEgens have been integrated into fiber, endowing the fiber with prominent fluorescence and/or photosensitizing capacities. AIEgens and fiber complement each other for making progress in flexible smart materials, in which the utilization of AIEgens creates new application possibilities for fiber, and the fiber provides an excellent carrier for AIEgens towards realizing the conversion from molecule to materials and an ideal platform to research the aggregate state of AIEgens in mesoscale and macroscale. This review begins with a brief summary of the recent advances related to some typical AIEgens with various functions and the technology for the fabrication of AIEgen-functionalized fiber. The most representative applications are then highlighted by focusing on energy conversion, personal protective equipment, biomedical, sensor, and fluorescence-related fields. Finally, the challenges, opportunities, and tendencies in future development are discussed in detail. This review hopes to inspire innovation in AIEgens and fiber from the view of mesoscale and macroscale.

Mitochondria-targeting NIR AIEgens with cationic amphiphilic character for imaging and efficient photodynamic therapy

A new dual-cationic amphiphilic AIEgen TPhBT-PyP with NIR emission and efficient ¹O₂ generation was designed. The amphiphilicity of TPhBT-PyP was tuned with dual-positive charges of pyridinium and TPP groups, efficiently targeting mitochondria and distinguishing Gram-positive bacteria. TPhBT-PyP performed well in photodynamic therapy, inducing cancer cell apoptosis and killing S. aureus bacteria.