Acceptor Planarization and Donor Rotation: A Facile Strategy for Realizing Synergistic Cancer Phototherapy via Type I PDT and PTT

Electron-Withdrawing Substituents Enhance the Type I PDT and NIR-II Fluorescence of BODIPY J Aggregates for Bioimaging and Cancer Therapy

Organic dyes with simultaneously boosted near-infrared-II (NIR-II) fluorescence, type I photodynamic therapy (PDT), and photothermal therapy (PTT) in the aggregate state are still elusive due to the unclear structure-function relationship. Herein, electron-withdrawing substituents are introduced at the 5-indolyl positions of BODIPY dyes to form tight J-aggregates for enhanced NIR-II fluorescence and type I PDT/PTT. The introduction of an electron-rich julolidine group at the meso position and an electron-withdrawing substituent (-F) at the indolyl moiety can enhance intermolecular charge transfer and the hydrogen bonding effect, contributing to the efficient generation of superoxide radicals in the aggregate state. The nanoparticles of BDP-F exhibit NIR-II fluorescence at 1000 nm, good superoxide radical generation ability, and a high photothermal conversion efficiency (50.9%), which enabled NIR-II fluorescence-guided vasculature/tumor imaging and additive PDT/PTT. This work provides a strategy for constructing phototheranostic agents with enhanced NIR-II fluorescence and type I PDT/PTT for broad biomedical applications.

Molecular engineering design of twisted-backbone pure Type-I organic photosensitizers for hypoxic photodynamic therapy

Photodynamic therapy (PDT), an emerging tumor therapeutic strategy has received tremendous attention. Enslaved by the high dependence of oxygen, Type-II photosensitizers (PSs) mediated PDT is restricted by the hypoxic environment of tumors. By transferring electrons to water or other substrates instead of oxygen, Type-I PSs hold the promise of achieving an ideal therapeutic effect under hypoxic conditions. In this study, three twisted-backbone PSs (CBz-TQs-1, CBz-TQs-2 and CBz-TQs-3) are synthesized and studied. Owing to different substituent effects, the ROS generation mechanism transfers from pure Type-II of their prototype PSs (TQs-1, TQs-2 and TQs-3) to mixed Type-I/II of CBz-TQs-1 and CBz-TQs-2 to pure Type-I of CBz-TQs-3. Moreover, CBz-TQs-3 exhibits an ultra-high ROS quantum yield (∼1.0). The in vitro and in vivo PDT effects of water-dissolvable nanoparticles (NPs) of CBz-TQs-3 are investigated. The results show that the phototoxicity of CBz-TQs-3 is not affected by hypoxic environments. In addition, a remarkable tumor ablation can be found after CBz-TQs-3 NPs mediated PDT on Balb/c mice with xenograft tumors. It proves that a twisted backbone strategy is beneficial for designing pure Type-I PSs with high-efficient hypoxic PDT.

Regulating donor configuration to develop AIE-active type I photosensitizers for lipid droplet imaging and high-performance photodynamic therapy under hypoxia

Type I photodynamic therapy is considered to be a more promising cancer treatment than type II photodynamic therapy due to its non-oxygen-dependent characteristics. In this work, three D-A structure N,N'-dihydrophenazine (DHP)-based photosensitizers DP-CNPY, SMP-CNPY and DMP-CNPY were designed and synthesized by introducing different numbers of methyl groups in the backbone neighbor of DHP as the donor and combined with the typical strong electron acceptor 2-(pyridin-4-yl)acetonitrile. Among the three photosensitizers, SMP-CNPY with one methyl modification showed the best type I ROS (O2-˙, ˙OH) generation capacity and AIE performance. By encapsulation, SMP-CNPY was fabricated into nanoparticles, and SMP-CNPY NPs exhibited lipid droplet targeting ability with near-infrared (NIR) emission. Cell experiments have proved that SMP-CNPY NPs can effectively kill different kinds of cancer cells under normal oxygen conditions. Even under hypoxic and extreme hypoxic conditions, SMP-CNPY NPs can still produce ROS and kill cancer cells. This work holds significant potential in the field of type I AIE-active photosensitizers and provides a new strategy for overcoming the hypoxic dilemma in the malignant tumor microenvironment.

Near-Infrared-II Nanomaterials for Activatable Photodiagnosis and Phototherapy

Near-Infrared-II (NIR-II) spans wavelengths between 1,000 to 1,700 nanometers, featuring deep tissue penetration and reduced tissue scattering and absorption characteristics, providing robust support for cancer treatment and tumor imaging research. This review explores the utilization of activatable NIR-II photodiagnosis and phototherapy based on tumor microenvironments (e. g., reactive oxygen species, pH, glutathione, hypoxia) and external stimulation (e. g., laser, ultrasound, photothermal) for precise tumor treatment and imaging. Special emphasis is placed on the advancements and advantages of activatable NIR-II nanomedicines in novel therapeutic modalities like photodynamic therapy, photothermal therapy, and photoacoustic imaging. This encompasses achieving deep tumor penetration, real-time monitoring of the treatment process, and obtaining high-resolution, high signal-to-noise ratio images even at low material concentrations. Lastly, from a clinical perspective, the challenges faced by activatable NIR-II phototherapy are discussed, alongside potential strategies to overcome these hurdles.

Exclusive and Switchable Superoxide Radical Generation by O2-Capture-Based Electron Transfer and Supramolecular Assembly

Type-I photosensitizers (PSs) can generate free radical anions with a broad diffusion range and powerful damage effect, rendering them highly desirable in various areas. However, it still remains a recognized challenge to develop pure Type-I PSs due to the inefficiency in producing oxygen radical anions through the collision of PSs with nearby substrates. In addition, regulating the generation of oxygen radical anions is also of great importance toward the control of photosensitizer (PS) activities on demand. Herein, a piperazine-based cationic Type-I PS (PPE-DPI) that exhibits efficient intersystem crossing and subsequently captures oxygen molecules through binding O2 to the lone pair of nitrogen in piperazine is reported. The close spatial vicinity between O2 and PPE-DPI strongly promotes the electron transfer reaction, ensuring the exclusive superoxide radical (O2 •-) generation via Type-I process. Particularly, PPE-DPI with cationic pyridine groups is able to associate with cucurbit[7]uril (CB[7]) through host-guest interactions. Thus, supramolecular assembly and disassembly are easily utilized to realize switchable O2 •- generation. This switchable Type-I PS is successfully employed in photodynamic antibacterial control.

Image-Guided Photothermal and Immune Therapy of Tumors via Melanin-Producing Genetically Engineered Bacteria

Photothermal therapy (PTT) is a new treatment modality for tumors. However, the efficient delivery of photothermal agents into tumors remains difficult, especially in hypoxic tumor regions. In this study, an approach to deliver melanin, a natural photothermal agent, into tumors using genetically engineered bacteria for image-guided photothermal and immune therapy is developed. An Escherichia coli MG1655 is transformed with a recombinant plasmid harboring a tyrosinase gene to produce melanin nanoparticles. Melanin-producing genetically engineered bacteria (MG1655-M) are systemically administered to 4T1 tumor-bearing mice. The tumor-targeting properties of MG1655-M in the hypoxic environment integrate the properties of hypoxia targeting, photoacoustic imaging, and photothermal therapeutic agents in an "all-in-one" manner. This eliminates the need for post-modification to achieve image-guided hypoxia-targeted cancer photothermal therapy. Tumor growth is significantly suppressed by irradiating the tumor with an 808 nm laser. Furthermore, strong antitumor immunity is triggered by PTT, thereby producing long-term immune memory effects that effectively inhibit tumor metastasis and recurrence. This work proposes a new photothermal and immune therapy guided by an "all-in-one" melanin-producing genetically engineered bacteria, which can offer broad potential applications in cancer treatment.

Self-Adaptive Photodynamic-to-Photothermal Switch for Smart Antitumor Photoimmunotherapy

Photodynamic therapy (PDT) and photothermal therapy (PTT) possess different merits in cancer phototherapy, but the tumor microenvironment becomes unfavorable during the phototheranostic progress. Herein, we report a self-adaptive cyanine derivative Cy5-TPA with the PDT-dominated state to PTT-dominated state autoswitch feature for enhanced photoimmunotherapy. The incorporation of rotatable triphenylamine (TPA) moiety renders Cy5-TPA with the temperature or intramolecular-motion regulated photoactivities, which shows preferable reactive oxygen species (ROS) generation at lower temperature while stronger photothermal conversion at higher ones. Such a promising feature permits the in situ switch from PDT-dominated state to PTT-dominated state along with intratumoral temperature increase during laser irradiation, which also works in line with the concurrently reduced intratumoral oxygen level, exhibiting a self-adaptive phototherapeutic behavior to maximize the phototherapeutic antitumor outcome. Most importantly, the self-adaptive PDT-dominated state to PTT-dominated state switch also facilitates the sequential generation and release of damage-associated molecular patterns during immunogenic cell death (ICD). Hence, Cy5-TPA demonstrates excellent photoimmunotherapy performance in ICD induction, dendritic cell maturation, and T cell activation for tumor eradication and metastasis inhibition.

Photothermal therapy: a novel potential treatment for prostate cancer

Prostate cancer (PCa) is a leading cause of cancer-related death in men, and most PCa patients treated with androgen deprivation therapy will progress to metastatic castration-resistant prostate cancer (mCRPC) due to the lack of efficient treatment. Recently, lots of research indicated that photothermal therapy (PTT) was a promising alternative that provided an accurate and efficient prostate cancer therapy. A photothermic agent (PTA) is a basic component of PPT and is divided into organic and inorganic PTAs. Besides, the combination of PTT and other therapies, such as photodynamic therapy (PDT), immunotherapy (IT), chemotherapy (CT), etc., provides an more efficient strategy for PCa therapy. Here, we introduce basic information about PTT and summarize the PTT treatment strategies for prostate cancer. Based on recent works, we think the combination of PPT and other therapies provides a novel possibility for PCa, especially CRPC clinical treatment.

Photothermal Ferrotherapy - Induced Immunogenic Cell Death via Iron-Based Ternary Chalcogenide Nanoparticles Against Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is highly malignant and prone to recurrence and metastasis. Patients with TNBC have limited therapeutic options, often resulting in poor prognosis. Some new treatments for TNBC have been considered in the past decade, such as immunotherapy, photothermal therapy (PTT), and ferroptosis therapy, that allow the rapid and minimally invasive ablation of cancer. However, a multifunctional nanodrug system with more potent efficacy for TNBC is still needed. The use of iron-based ternary chalcogenide nanoparticles (NPs), namely AgFeS2, is reported, which synergistically combines photothermal therapy, ferrotherapy, and immunotherapy in one system for the treatment of TNBC. AgFeS2 possesses excellent photothermal conversion performance for tumor near-infrared (NIR) phototherapy. Upon photoirradiation, these NPs generate heat, accelerate the release of iron ions, and effectively catalyze the Fenton reaction, resulting in cell apoptosis and ferroptosis. Additionally, AgFeS2 promotes the release of tumor-specific antigens and triggers an immune response via immunogenic cell death (ICD), thereby providing unique synergistic mechanisms for cancer therapy. The present study demonstrates the great potential of iron-based ternary chalcogenide as a new therapeutic platform for a combination of photothermal therapy, ferrotherapy, and immunotherapy for the suppression of TNBC.

Near-Infrared Light-Driven Nanoparticles for Cancer Photoimmunotherapy by Synergizing Immune Cell Death and Epigenetic Regulation

Histone deacetylases (HDACs) are a class of epigenetic enzymes that are closely related to tumorigenesis and suppress the expression of tumor suppressor genes. Whereas the HDACs inhibitors can release DNA into the cytoplasm and trigger innate immunity. However, the high density of chromatin limits DNA damage and release. In this study, suitable nanosized CycNHOH NPs (150 nm) and CypNHOH NPs (85 nm) efficiently accumulate at the tumor site due to the enhanced permeability and retention (EPR) effect. In addition, robust single-linear oxygen generation and good photothermal conversion efficiency under NIR laser irradiation accelerated the DNA damage process. By effectively initiating immune cell death, CypNHOH NPs activated both innate and adaptive immunity by maturing dendritic cells, infiltrating tumors with natural killer cells, and activating cytotoxic T lymphocytes, which offer a fresh perspective for the development of photo-immunotherapy.

Deciphering Oxygen-Independent Augmented Photodynamic Oncotherapy by Facilitating the Separation of Electron-Hole Pairs

Developing Type-I photosensitizers provides an attractive approach to solve the dilemma of inadequate efficacy of photodynamic therapy (PDT) caused by the inherent oxygen consumption of traditional Type-II PDT and anoxic tumor microenvironment. The challenge for the exploration of Type-I PSs is to facilitate the electron transfer ability of photosensitization molecules for transforming oxygen or H2O to reactive oxygen species (ROS). Herein, we propose an electronic acceptor-triggered photoinduced electron transfer (a-PET) strategy promoting the separation of electron-hole pairs by marriage of two organic semiconducting molecules of a non-fullerene scaffold-based photosensitizer and a perylene diimide that significantly boost the Type-I PDT pathway to produce plentiful ROS, especially, inducing 3.5-fold and 2.5-fold amplification of hydroxyl (OH⋅) and superoxide (O2 -⋅) generation. Systematic mechanism exploration reveals that intermolecular electron transfer and intramolecular charge separation after photoirradiation generate a competent production of radical ion pairs that promote the Type-I PDT process by theoretical calculation and ultrafast femtosecond transient absorption (fs-TA) spectroscopy. By complementary tumor diagnosis with photoacoustic imaging and second near-infrared fluorescence imaging, this as-prepared nanoplatform exhibits fabulous photocytotoxicity in harsh hypoxic conditions and terrific cancer revoked abilities in living mice. We envision that this work will broaden the insight into high-efficiency Type-I PDT for cancer phototheranostics.

A Dual-Function Hemicyanine Material with Highly Efficient Photothermal and Photodynamic Effect Used for Tumor Therapy

Small molecular organic optical agents with synergistic effects of photothermal therapy (PTT) and photodynamic therapy (PDT), hold credible promise for anti-tumor therapy by overcoming individual drawbacks and enhancing photon utilization efficiency. However, developing effective dual-function PTT-PDT photosensitizers (PSs) for efficient synergistic phototherapy remains challenging. Here, a benz[c,d]indolium-substituted hemicyanine named Rh-BI, which possesses a high photothermal conversion efficiency of 41.67% by exhaustively suppressing fluorescence emission, is presented. Meanwhile, the rotating phenyl group at meso-site induces charge recombination to enhance the molar extinction coefficient up to 13.58 × 104 M-1cm-1, thereby potentiating the photodynamic effect. Under 808 nm irradiation, Rh-BI exhibits significant phototoxicity in several cancer cell types in vitro with IC50 values as low as ≈0.5 µM. Moreover, treatment of 4T1 tumor-bearing mice with Rh-BI under laser irradiation successfully inhibits tumor growth. In a word, an effective strategy is developed to build PTT-PDT dual-functional optical materials based on hemicyanine backbone for tumor therapy by modulating conjugation system interaction to adjust the energy consumption pathway.

End Group Engineering for Constructing A-D-A Fused-Ring Photosensitizers with Balanced Phototheranostics Performance

Phototheranostics continues to flourish in cancer treatment. Due to the competitive relationships between these photophysical processes of fluorescence emission, photothermal conversion, and photodynamic action, it is critical to balance them through subtle photosensitizer designs. Herein, it is provided a useful guideline for constructing A-D-A photosensitizers with superior phototheranostics performance. Various cyanoacetate group-modified end groups containing ester side chains of different length are designed to construct a series of A-D-A photosensitizers (F8CA1 ∼ F8CA4) to study the structure-property relationships. It is surprising to find that the photophysical properties of A-D-A photosensitizers can be precisely regulated by these tiny structural changes. The results reveal that the increase in the steric hindrance of ester side chains has positive impacts on their photothermal conversion capabilities, but adverse impacts on the fluorescence emission and photodynamic activities. Notably, these tiny structural changes lead to their different aggregation behavior. The molecule mechanisms are detailedly explained by theoretical calculations. Finally, F8CA2 nanoparticles with more balanced photophysical properties perform well in fluorescence imaging-guided photothermal and type I&II photodynamic synergistic cancer therapy, even under hypoxic conditions. Therefore, this work provides a novel practicable construction strategy for desired A-D-A photosensitizers.

Aggregation-Induced Emission Photosensitizer-Engineered Anticancer Nanomedicine for Synergistic Chemo/Chemodynamic/Photodynamic Therapy

Photodynamic therapy (PDT) with aggregation-induced emission (AIE) photosensitizers (PSs) is a promising therapeutic strategy to achieve better anticancer results. However, eradicating solid tumors completely by PDT alone can be difficult owing to the inherent drawbacks of this treatment, and the combination of PDT with other therapeutic modalities provides opportunities to achieve cooperative enhancement interactions among various treatments. Herein, this work presents the construction of a biocompatible nanocomposite, namely CaO2@DOX@ZIF@ASQ, featuring light-responsive reactive oxygen species (ROS) generation and tumor-targeting oxygen and hydrogen peroxide discharge, as well as controlled doxorubicin (DOX) and copper ion release, thus allowing the combined PDT/CT/CDT effect by AIE PS-enhanced PDT, DOX-based chemotherapy (CT), and copper-involved Fenton-like reaction-driven chemodynamic therapy (CDT). In vitro and in vivo studies verify that the generation of both ROS and O2 by this nanomedicine, stimulated by light, exhibits superior anticancer efficacy, alleviating tumor hypoxia and achieving synergistic PDT/CT/CDT therapeutic effect. This multifunctional nanomedicine remarkably suppresses the tumor growth with minimized systemic toxicity, providing a new strategy for constructing multimodal PDT/CT/CDT therapeutic systems to overcome hypoxia limitations, and potentially increase the antitumor efficacy at lower doses of PSs and chemotherapeutic drugs, thus minimizing potential toxicity to non-malignant tissues.

Rotor-based image-guided therapy of glioblastoma

Glioblastoma (GBM), deep in the brain, is more challenging to diagnose and treat than other tumors. Such challenges have blocked the development of high-impact therapeutic approaches that combine reliable diagnosis with targeted therapy. Herein, effective cyanine dyes (IRLy) with the near-infrared two region (NIR-II) adsorption and aggregation-induced emission (AIE) have been developed via an "extended conjugation & molecular rotor" strategy for multimodal imaging and phototherapy of deep orthotopic GBM. IRLy was synthesized successfully through a rational molecular rotor modification with stronger penetration, higher signal-to-noise ratio, and a high photothermal conversion efficiency (PCE) up to ∼60%, which can achieve efficient NIR-II photo-response. The multifunctional nanoparticles (Tf-IRLy NPs) were further fabricated to cross the blood-brain barrier (BBB) introducing transferrin (Tf) as a targeting ligand. Tf-IRLy NPs showed high biosafety and good tumor enrichment for GBM in vitro and in vivo, and thus enabled accurate, efficient, and less invasive NIR-II multimodal imaging and photothermal therapy. This versatile Tf-IRLy nanosystem can provide a reference for the efficient, precise and low-invasive multi-synergistic brain targeted photo-theranostics. In addition, the "extended conjugation & molecular rotor" strategy can be used to guide the design of other photothermal agents.

A biodegradable semiconducting polymer phototherapeutic agent for safe cancer phototherapy

Combined photodynamic therapy (PDT) and photothermal therapy (PTT) not only effectively reduce the hypoxic resistance to PDT, but also overcome the heat shock effect to PTT. However, the residual phototherapeutic agents still produce reactive oxygen species (ROS) to damage normal tissue under sunlight after treatment, which induces undesirable side effects to limit their biomedical application. Herein, a facile strategy is proposed to construct a biodegradable semiconducting polymer p-DTT, which is constructed by thieno[3,2-b]thiophene modified diketopyrrolopyrrole and (E)-1,2-bis(5-(trimethylstannyl)thiophen-2-yl)ethene moieties, to avoid the post-treatment side effects of phototherapy. Additionally, p-DTT exhibits strong photoacoustic (PA) for imaging, as well as good ROS production capacity and high photothermal conversion efficiency for synergistic PDT and PTT, which has been confirmed by both in vitro and in vivo results. After phototherapy, p-DTT could be gradually oxidized and degraded by endogenous ClO-, and subsequently lose ROS production and photothermal conversion capacities, which can guarantee the post-treatment safety, and address above key limitation of traditional phototherapy.

Oxygen-independent organic photosensitizer with ultralow-power NIR photoexcitation for tumor-specific photodynamic therapy

Photodynamic therapy (PDT) is a promising cancer treatment but has limitations due to its dependence on oxygen and high-power-density photoexcitation. Here, we report polymer-based organic photosensitizers (PSs) through rational PS skeleton design and precise side-chain engineering to generate •O2- and •OH under oxygen-free conditions using ultralow-power 808 nm photoexcitation for tumor-specific photodynamic ablation. The designed organic PS skeletons can generate electron-hole pairs to sensitize H2O into •O2- and •OH under oxygen-free conditions with 808 nm photoexcitation, achieving NIR-photoexcited and oxygen-independent •O2- and •OH production. Further, compared with commonly used alkyl side chains, glycol oligomer as the PS side chain mitigates electron-hole recombination and offers more H2O molecules around the electron-hole pairs generated from the hydrophobic PS skeletons, which can yield 4-fold stronger •O2- and •OH production, thus allowing an ultralow-power photoexcitation to yield high PDT effect. Finally, the feasibility of developing activatable PSs for tumor-specific photodynamic therapy in female mice is further demonstrated under 808 nm irradiation with an ultralow-power of 15 mW cm-2. The study not only provides further insights into the PDT mechanism but also offers a general design guideline to develop an oxygen-independent organic PS using ultralow-power NIR photoexcitation for tumor-specific PDT.

Theranostic Fluorescent Probes

The ability to gain spatiotemporal information, and in some cases achieve spatiotemporal control, in the context of drug delivery makes theranostic fluorescent probes an attractive and intensely investigated research topic. This interest is reflected in the steep rise in publications on the topic that have appeared over the past decade. Theranostic fluorescent probes, in their various incarnations, generally comprise a fluorophore linked to a masked drug, in which the drug is released as the result of certain stimuli, with both intrinsic and extrinsic stimuli being reported. This release is then signaled by the emergence of a fluorescent signal. Importantly, the use of appropriate fluorophores has enabled not only this emerging fluorescence as a spatiotemporal marker for drug delivery but also has provided modalities useful in photodynamic, photothermal, and sonodynamic therapeutic applications. In this review we highlight recent work on theranostic fluorescent probes with a particular focus on probes that are activated in tumor microenvironments. We also summarize efforts to develop probes for other applications, such as neurodegenerative diseases and antibacterials. This review celebrates the diversity of designs reported to date, from discrete small-molecule systems to nanomaterials. Our aim is to provide insights into the potential clinical impact of this still-emerging research direction.

Photoinduced Cuproptosis with Tumor-Specific for Metastasis-Inhibited Cancer Therapy

Cuproptosis is a novel form of regulated cell death which guarantees to increase the efficacy of existing anticancer treatments that employ traditional apoptotic therapeutics. However, reducing the amount of undesirable Cu ions released in normal tissue and maximizing Cu-induced cuproptosis therapeutic effects at tumor sites are the major challenges. In this study, exploiting the chemical properties of copper ionophores and the tumor microenvironment, a novel method is developed for controlling the valence of copper ions that cause photoinduced cuproptosis in tumor cells. CJS-Cu nanoparticles (NPs) can selectively induce cuproptosis after cascade reactions through H2 O2 -triggered Cu2+ release, photoirradiation-induced superoxide radical (∙O2 - ) generation, and reduction of Cu2+ to Cu+ by ∙O2 - . The generated reactive oxygen species can result in glutathione depletion and iron-sulfur cluster protein damage and further augmented cuproptosis. CJS-Cu NPs effectively suppressed tumor growth and downregulated the expression of metastasis-related proteins, contributing to the complete inhibition of lung metastasis. Ultimately, this study suggests novel avenues for the manipulation of cellular cuproptosis through photochemical reactions.

Toward Type I/II ROS Generation Photoimmunotherapy by Molecular Engineering of Semiconducting Perylene Diimide

As prospective phototheranostic agents for cancer imaging and therapy, semiconducting organic molecule-based nanomedicines are developed. However, near-infrared (NIR) emission, and tunable type I (O2 • -) and type II (1O2) photoinduced reactive oxygen species (ROS) generation to boost cancer photoimmunotherapy remains a big challenge. Herein, a series of D-π-A structures, NIR absorbing perylene diimides (PDIs) with heavy atom bromide modification at the bay position of PDIs are prepared for investigating the optimal photoinduced type I/II ROS generation. The heavy atom effect has demonstrated a reduction of molecular ∆EST and promotion of the intersystem crossing processes of PDIs, enhancing the photodynamic therapy (PDT) efficacy. The modification of three bromides and one pyrrolidine at the bay position of PDI (TBDT) has demonstrated the best type I/II PDT performance by batch experiments and theoretical calculations. TBDT based nanoplatforms (TBDT NPs) enable type I/II PDT in the hypoxic tumor microenvironment as a strong immunogenic cell death (ICD) inducer. Moreover, TBDT NPs showing NIR emission allow in vivo bioimaging guided phototherapy of tumor. This work uses novel PDIs with adjustable type I/II ROS production to promote antitumor immune response and accomplish effective tumor eradication, consequently offering molecular guidelines for building high-efficiency ICD inducers.

Photoactivation Inducing Multifunctional Coupling of Fluorophore for Efficient Tumor Therapy In Situ

Photoactivatable molecules, with high-precision spatialtemporal control, have largely promoted bioimaging and phototherapy applications of fluorescent dyes. Here, the first photoactivatable sensor (BI) is described that can be triggered by broad excitation light (405-660 nm), which further undergoes intersystem crossing and H-atom transfer processes to forming superoxide anion radicals (O2 -• ) and carbon radicals. Particularly, the photoinduced gain of carbon-centered radicals (BI•) allows for radical-radical coupling to afford the combined crosslink product (BI─BI), which would be oxidized in the presence of O2 -• to produce an extended conjugate system with near infrared emission (820 nm). Besides, the photochemically generated product (Cy─BI) possesses ultra-high photothermal conversion efficiency up to 90.9%, which optimized phototherapy potential. What's more, Western Blot assay reveals that both BI and the photoproduct Cy─BI can efficiently inhibit the expression of CHK1, and the irradiation of BI and Cy─BI further induces apoptosis and ultimately enhances the phototherapeutic effects. Thus, the combination of cell cycle block inducing apoptosis, photodynamic therapy and photothermal therapy treatments significantly suppress solid tumor in vivo antitumor efficacy explorations. This is a novel finding in developing photoactivatable molecules, as well as the broad applicability of photoimaging and phototherapy in tumor-related areas.

Acid-triggered controlled release and fluorescence-switchable phthalocyanine nanoassemblies combined with O2-economizer for tumor imaging and collaborative photodynamic antitumor therapy

Photodynamic therapy (PDT) has emerged as a highly efficacious therapeutic modality for malignant tumors owing to its non-invasive property and minimal adverse effects. However, the pervasive hypoxic microenvironment within tumors significantly compromises the efficacy of oxygen-dependent PDT, posing a formidable challenge to the advancement of high-efficiency PDT. Here, we developed a nanostructured photosensitizer (PS) assembled by cationic and anionic zinc phthalocyanines to load oxygen-throttling drug atovaquone (ATO), which was subsequently coated with polydopamine to obtain the final product ATO/ZnPc-CA@DA. ATO/ZnPc-CA@DA exhibited excellent stability, particularly in the blood milieu. Interestingly, the acidic microenvironment can trigger drug release from ATO/ZnPc-CA@DA, leading to a significant enhancement in fluorescence and an augmented generation of reactive oxygen species (ROS). ATO/ZnPc-CA@DA can induce synergistic cytotoxicity of PS and ATO, and significantly enhance the killing ability against tumor cells under hypoxic conditions. The mechanism underlying cytotoxicity of ATO/ZnPc-CA@DA was demonstrated to be associated with augmented cell apoptosis, disruption of mitochondrial membrane potential, diminished ATP production, heightened intracellular ROS generation, and reduced intracellular oxygen consumption. The animal experiments indicated that ATO/ZnPc-CA@DA possessed enhanced tumor targeting capability, along with a reduction in PS distribution within normal organs. Furthermore, ATO/ZnPc-CA@DA exhibited enhanced inhibitory effect on tumor growth and caused aggravated damage to tumor tissue. The construction strategy of nanostructured PS and the synergistic antitumor principle of combined oxygen-throttling drugs can be applied to other PSs, thereby advancing the development of photodynamic antitumor therapy and promoting the clinical translation.

Promoting the Near-Infrared-II Fluorescence of Diketopyrrolopyrrole-Based Dye for In Vivo Imaging via Donor Engineering

Small-molecule dyes for fluorescence imaging in the second near-infrared region (NIR-II, 900-1880 nm) hold great promise in clinical applications. Constructing donor-acceptor-donor (D-A-D) architectures has been recognized to be a feasible strategy to achieve NIR-II fluorescence. However, the development of NIR-II dyes via such a scheme is hampered by the lack of high-performance electron acceptors and donors. Diketopyrrolopyrrole (DPP), as a classic organic optoelectronic material, enjoys strong light absorption, high fluorescence quantum yield (QY), and facile derivatization. Nevertheless, its application in the NIR-II imaging field has been hindered by its limited electron-withdrawing ability and the aggregation-caused quenching (ACQ) effect resulting from the planar structure of DPP. Herein, with DPP as an electron acceptor and through donor engineering, we have successfully designed and synthesized a DPP-based dye named T-27, in which the strong D-A interaction confers excellent NIR absorption and high-brightness NIR-II fluorescence tail emission. By strategically introducing long alkyl chains on the donor unit to increase intermolecular spacing and reduce the influence of solvent molecules, T-27 exhibits an improved anti-ACQ effect in aqueous solutions. After being encapsulated into DSPE-PEG2000, T-27 nanoparticles (NPs) show a relative NIR-II fluorescence QY of 3.4% in water, representing the highest value among the DPP-based NIR-II dyes reported to date. The outstanding photophysical properties of T-27 NPs enable multimode NIR-IIa bioimaging under 808 nm excitation. As such, the T-27 NPs can distinguish mouse femoral vein and artery and achieve cerebral vascular microscopic imaging with a penetrating depth of 800 μm, demonstrating the capability for high-resolution deep-tissue imaging. This work holds significant potential in the field of bioimaging and provides a new strategy for developing bright NIR-II dyes.

Targeting Lysosome for Enhanced Cancer Photodynamic/Photothermal Therapy in a "One Stone Two Birds" Pattern

Highly immunogenic programmed death of tumor cells, such as immunogenic cell death (ICD) and pyroptosis, strengthens antitumor responses and thus represents a promising target for cancer immunotherapy. However, the development of ICD and pyroptosis inducers remains challenging, and their efficiency is typically compromised by self-protective autophagy. Here, we report a potent ICD and pyroptosis-inducing strategy by coupling combined photodynamic/photothermal therapy (PTT/PDT) to biological processes in cancer cells. For this purpose, we rationally synthesize a lysosomal-targeting boron-dipyrromethene dimer (BDPd) with intense NIR absorption/emission, high reactive oxygen species (ROS) yield, and photothermal abilities, which can be self-assembled with Pluronic F127, producing lysosomal-acting nanomicelles (BDPd NPs) to facilitate cancer cell internalization of BDPd and generation of intracellular ROS. Owing to the favorable lysosomal-targeting ability of the morpholine group on BDPd, the intracellular BDPd NPs can accumulate in the lysosome and induce robust lysosomal damage in cancer cells upon 660 nm laser irradiation, which results in the synergetic induction of pyroptosis and ICD via activating NLRP3/GSDMD and caspase-3/GSDME pathways simultaneously. More importantly, PTT/PDT-induced self-protective autophagic degradation was blocked due to the dysfunction of lysosomes. Either intratumorally or intravenously, the injected BDPd NPs could markedly inhibit the growth of established tumor tissues upon laser activation, provoke local and systemic antitumor immune responses, and prolong the survival time in the mouse triple-negative breast cancer model. Collectively, this work represents a promising strategy to boost the therapeutic potential of PTT/PDT by coupling phototherapeutic reagents with the subcellular organelles, creating a "one stone two birds" pattern.

J-Aggregation Strategy toward Potentiated NIR-II Fluorescence Bioimaging of Molecular Fluorophores

Molecular fluorophores emitting in the second near-infrared (NIR-II, 1000-1700 nm) window with strong optical harvesting and high quantum yields hold great potential for in vivo deep-tissue bioimaging and high-resolution biosensing. Recently, J-aggregates are harnessed to engineer long-wavelength NIR-II emitters and show unique superiority in tumor detection, vessel mapping, surgical navigation, and phototheranostics due to their bathochromic-shifted optical bands in the required slip-stacked arrangement aggregation state. However, despite the preliminary progress of NIR-II J-aggregates and theoretical study of structure-property relationships, further paradigms of NIR-II J-aggregates remain scarce due to the lack of study on aggregated fluorophores with slip-stacked fashion. In this effort, how to utilize the specific molecular structure to form slip-stacked packing motifs with J-type aggregated exciton coupling is emphatically elucidated. First, several molecular regulating strategies to achieve NIR-II J-aggregates containing intermolecular interactions and external conditions are positively summarized and deeply analyzed. Then, the recent reports on J-aggregates for NIR-II bioimaging and theranostics are systematically summarized to provide a clear reference and direction for promoting the development of NIR-II organic fluorophores. Eventually, the prospective efforts on ameliorating and promoting NIR-II J-aggregates to further clinical practices are outlined.

MXene-Decorated Nanofibrous Membrane with Programmed Antibacterial and Anti-Inflammatory Effects via Steering NF-κB Pathway for Infectious Cutaneous Regeneration

Although antibiotic is still the main choice for antibacteria both in hospital and community, phototherapy has become a possibly one of the alternative approaches in the treatment of microbe-associated infections nowadays because of its considerable potential in effective eradication of pathogenic bacteria. However, overwhelming reactive oxygen species (ROS) generated from phototherapy inevitably provoke an inflammatory response, complicating the healing process. To address this outstanding issue, a MXene-decorated nanofibrious is devised that not only yield localized heat but also elevate ROS levels under near-infrared laser exposure ascribed to the synergistic photothermal/photodynamic effect, for potent bacterial inactivation. After being further loaded with aspirin, the nanofibrous membranes exhibit benign cytocompatibility, boosting cell growth and suppressing the (nuclear factor kappa-B ( NF-κB) signaling pathways through RNA sequencing analysis, indicating an excellent anti-inflammatory effect. Interestingly, in vivo investigations also corroborate that the nanofibrous membranes accelerate infectious cutaneous regeneration by efficiently killing pathogenic bacteria, promoting collagen deposition, boosting angiogenesis, and dampening inflammatory reaction via steering NF-κB pathway. As envisaged, this work furnishes a decorated nanofibrous membrane with programmed antibacterial and anti-inflammatory effects for remedy of refractory bacteria-invaded wound regeneration.

Recent advances in aggregation-induced emission-active type I photosensitizers with near-infrared fluorescence: From materials design to therapeutic platform fabrication

Near-infrared (NIR) fluorescence imaging-guided photodynamic therapy (PDT) technology plays an important role in treating various diseases and still attracts increasing research interests for developing novel photosensitizers (PSs) with outstanding performances. Conventional PSs such as porphyrin and rhodamine derivatives have easy self-aggregation properties in the physiological environment due to their inherent hydrophobic nature caused by their rigid molecular structure that induces strong intermolecular stacking π-π interaction, leading to serious fluorescence quenching and cytotoxic reactive oxygen species (ROS) reduction. Meanwhile, hypoxia is an inherent barrier in the microenvironment of solid tumors, seriously restricting the therapeutic outcome of conventional PDT. Aforementioned disadvantages should be overcome urgently to enhance the therapeutic effect of PSs. Novel NIR fluorescence-guided type I PSs with aggregation-induced emission (AIE), which features the advantages of improving fluorescent intensity and ROS generation efficiency at aggregation as well as outstanding oxygen tolerance, bring hope for resolving aforementioned problems simultaneously. At present, plenty of research works fully demonstrates the advancement of AIE-active PDT based on type I PSs. In this review, cutting-edge advances focusing on AIE-active NIR type I PSs that include the aspects of the photochemical mechanism of type I ROS generation, various molecular structures of reported type I PSs with NIR fluorescence and their design strategies, and typical anticancer applications are summarized. Finally, a brief conclusion is obtained, and the underlying challenges and prospects of AIE-active type I PSs are proposed.

Precise ligand engineering of Ir(III)-based photosensitizer with aggregation-induced emission for image-guided photodynamic therapy

Photodynamic therapy (PDT), which relies on the production of reactive oxygen species (ROS) induced by a photosensitizer to kill cancer cells, has become a non-invasive approach to combat cancer. However, the conventional aggregation-caused quenching effect, as well as the low ROS generation ability of photosensitizers, restrict their biological applications. In this work, a new Ir(III) complex with a dendritic ligand has been strategically designed and synthesized by ingenious modification of the ancillary ligand of a reported Ir(III) complex (Ir-1). The extended π-conjugation and multiple aromatic donor moieties endow the resulting complex Ir-2 with obvious aggregation-induced emission (AIE) activity and bathochromic emission. In in vitro experiments, importantly, Ir-2 nanoparticles exhibit the excellent photoinduced ROS generation capabilities of O2 •- and 1 O2 , as well as excellent biocompatibility and the lipid droplets (LDs) targeting feature. This study would provide useful guidance to design efficient Ir(III)-based photosensitizers used in biological applications in the future.

NIR-II Emissive Superoxide Radical Photogenerator for Photothermal/Photodynamic Therapy against Hypoxic Tumor

Due to the "Achilles' heels" of hypoxia, complicated location in solid tumor, small molecular photosensitizers with second near-infrared window (NIR-II) fluorescence, type-I photodynamic therapy (PDT), and photothermal therapy (PTT) have attracted great attention. However, these photosensitizers are still few but yet challenging. Herein, an "all in one" NIR-II acceptor-donor-acceptor fused-ring photosensitizer, Y6-Th, is presented for the in-depth diagnosis and efficient treatment of cancer. Benefiting from the strong intramolecular charge transfer, promoted highly efficient intersystem crossing, largely p-conjugated fused-ring structure, and reduced planarity, the fabricated nanoparticles (Y6-Th nanoparticles) can emit NIR-II fluorescence with the peak located at 1020 nm, exclusively generate O2•- for type-I PDT, and display excellent PTT performance under an 808 nm laser stimulation. These characteristics make Y6-Th a distinguished NIR-wavelength-triggered phototheranostic agent, which can effectively therapy the hypoxic tumor using NIR-II-fluorescence-guided type-I PDT/PTT. This work provides a valuable guideline for fabricating high-performing NIR-II emissive superoxide radical photogenerators.

Synthesis of germanium/germanium phosphide in-plane heterostructure with efficient photothermal and enhanced photodynamic effects in the second near-infrared biowindow

Inspired by the bifunctional phototherapy agents (PTAs), constructing compact PTAs with efficient photothermal therapy (PTT) and photodynamic therapy (PDT) effects in the near-infrared (NIR-II) biowindow is crucial for high therapeutic efficacy. Herein, none-layered germanium (Ge) is transformed to layered Ge/germanium phosphide (Ge/GeP) structure, and a novel two-dimensional sheet-like compact S-scheme Ge/GeP in-plane heterostructure with a large extinction coefficient of 15.66 L/g cm-1 at 1,064 nm is designed and demonstrated. In addition to the outstanding photothermal effects, biocompatibility and degradability, type I and type II PDT effects are activated by a single laser. Furthermore, enhanced reactive oxygen species generation under longer wavelength NIR laser irradiation is achieved, and production of singlet oxygen and superoxide radical upon 1,064 nm laser irradiation is more than double that under 660 nm laser irradiation. The S-scheme charge transfer mechanism between Ge and GeP, is demonstrated by photo-irradiated Kelvin probe force microscopy and electron spin resonance analysis. Thus, the obtained S-scheme Ge/GeP in-plane heterostructure shows synergistic therapeutic effects of PTT/PDT both in vitro and in vivo in the NIR-II biowindow and the novel nanoplatform with excellent properties has large clinical potential.

Nanomedicine Strategies in Conquering and Utilizing the Cancer Hypoxia Environment

Cancer with a complex pathological process is a major disease to human welfare. Due to the imbalance between oxygen (O2) supply and consumption, hypoxia is a natural characteristic of most solid tumors and an important obstacle for cancer therapy, which is closely related to tumor proliferation, metastasis, and invasion. Various strategies to exploit the feature of tumor hypoxia have been developed in the past decade, which can be used to alleviate tumor hypoxia, or utilize the hypoxia for targeted delivery and diagnostic imaging. The strategies to alleviate tumor hypoxia include delivering O2, in situ O2 generation, reprogramming the tumor vascular system, decreasing O2 consumption, and inhibiting HIF-1 related pathways. On the other side, hypoxia can also be utilized for hypoxia-responsive chemical construction and hypoxia-active prodrug-based strategies. Taking advantage of hypoxia in the tumor region, a number of methods have been applied to identify and keep track of changes in tumor hypoxia. Herein, we thoroughly review the recent progress of nanomedicine strategies in both conquering and utilizing hypoxia to combat cancer and put forward the prospect of emerging nanomaterials for future clinical transformation, which hopes to provide perspectives in nanomaterials design.

Near-Infrared-II Fluorophore with Inverted Dependence of Fluorescence Quantum Yield on Polarity as Potent Phototheranostics for Fluorescence-Image-Guided Phototherapy of Tumors

Organic phototheranostics simultaneously having fluorescence in the second near-infrared (NIR-II, 1000-1700 nm) window, and photothermal and photodynamic functions possess great prospects in tumor diagnosis and therapy. However, such phototheranostics generally suffer from low brightness and poor photodynamic performance due to severe solvatochromism. Herein, an organic NIR-II fluorophore AS1, which possesses an inverted dependence of fluorescence quantum yield on polarity, is reported to serve as potent phototheranostics for tumor diagnosis and therapy. After encapsulation of AS1 into nanostructures, the obtained phototheranostics (AS1R ) exhibit high extinction coefficients (e.g., 68200 L mol-1  cm-1 at 808 nm), NIR-II emission with high fluorescence quantum yield up to 4.7% beyond 1000 nm, photothermal conversion efficiency of ≈65%, and 1 O2 quantum yield up to 4.1%. The characterization of photophysical properties demonstrates that AS1R is superior to other types of organic phototheranostics in brightness, photothermal effect, and photodynamic performance at the same mass concentration. The excellent phototheranostic performance of AS1R enables clear visualization and complete elimination of tumors using a single and low injection dose. This study demonstrates the merits and prospects of NIR-II fluorophore with inverted polarity dependence of fluorescence quantum yield as high-performance phototheranostic agents for fluorescence imaging and phototherapy of tumors.

Asymmetric aza-BODIPY photosensitizer for photoacoustic/photothermal imaging-guided synergistic photodynamic/photothermal therapy

Cancer synergistic therapy usually shows improved therapeutic efficacy with low side effects. In this contribution, an aza-BODIPY-derived photosensitizer NBDP with asymmetric structure and the periphery phenyl ring modified with bromine atom was designed and synthesized for synergistic photothermal therapy (PTT) and photodynamic therapy (PDT). Photosensitizer NBDP exhibited good singlet oxygen (1O2) generation capacity (1.43 times higher than that of ICG), and NBDP NPs showed an outstanding photothermal conversion efficiency (η) of 46.0% under 660 nm photoirradiation. Guided by in vivo photoacoustic (PA) imaging, NBDP NPs were found to targetedly accumulate in the tumor tissues in 6 h. All results showed that the aza-BODIPY-derived photosensitizer NBDP had great potential for PA/photothermal imaging-guided synergistic PTT/PDT.

Mn2+ /Ir3+ -Doped and CaCO3 -Covered Prussian Blue Nanoparticles with Indocyanine Green Encapsulation for Tumor Microenvironment Modulation and Image-Guided Synergistic Cancer Therapy

The development of smart theranostic nanoplatforms has gained great interest in effective cancer treatment against the complex tumor microenvironment (TME), including weak acidity, hypoxia, and glutathione (GSH) overexpression. Herein, a TME-responsive nanoplatform named PMICApt /ICG, based on PB:Mn&Ir@CaCO3 Aptamer /ICG, is designed for the competent synergistic photothermal therapy and photodynamic therapy (PDT) under the guidance of photothermal and magnetic resonance imaging. The nanoplatform's aptamer modification targeting the transferrin receptor and the epithelial cell adhesion molecule on breast cancer cells, and the acid degradable CaCO3 shell allow for effective tumor accumulation and TME-responsive payload release in situ. The nanoplatform also exhibits excellent PDT properties due to its ability to generate O2 and consume antioxidant GSH in tumors. Additionally, the synergistic therapy is achieved by a single wavelength of near-infrared laser. RNA sequencing is performed to identify differentially expressed genes, which show that the expressions of proliferation and migration-associated genes are inhibited, while the apoptosis and immune response gene expressions are upregulated after the synergistic treatments. This multifunctional nanoplatform that responds to the TME to realize the on-demand payload release and enhance PDT induced by TME modulation holds great promise for clinical applications in tumor therapy.

Hybrid Polypyrrole and Polydopamine Nanosheets for Precise Raman/Photoacoustic Imaging and Photothermal Therapy

The development of near-infrared light responsive conductive polymers provides a useful theranostic platform for malignant tumors by maximizing spatial resolution with deep tissue penetration for diagnosis and photothermal therapy. Herein, the self-assembly of ultrathin 2D polypyrrole nanosheets utilizing dopamine as a capping agent and a monolayer of octadecylamine as a template is demonstrated. The 2D polypyrrole-polydopamine nanostructure has tunable size distribution which shows strong absorption in the first and second near-infrared windows, enabling photoacoustic imaging and photothermal therapy. The hybrid double-layer is demonstrated to increase Raman intensity for 3D Raman imaging (up to two orders of magnitude enhancement and spatial resolution up to 1 µm). The acidic environment drives reversible doping of polypyrrole, which can be detected by Raman spectroscopy. The combined properties of the nanosheets can substantially enhance performance in dual-mode Raman and photoacoustic guided photothermal therapy, as shown by the 69% light to heat conversion efficiency and higher cytotoxicity against cancer spheroids. These pH-responsive features highlight the potential of 2D conductive polymers for applications in accurate, highly efficient theranostics.

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.

Anion-π Interaction in a Diketopyrrolopyrrole Derivative

In this work, an N-substituted diketopyrrolopyrrole (DPP) derivative Ph-DPP was synthesized, showing interaction toward Lewis alkaline anions such as F-. The typical electron-transfer-dominated anion-π interaction product Ph-DPP•- and unexpected isomer product i-Ph-DPP were both observed, and their formation mechanism was studied by density functional theory calculations, suggesting that a deprotonation initiation route is favored, which gives interesting insight for understanding the debatable role of F- in such non-covalent intermolecular interactions.

Aggregation-Induced Emission (AIE), Life and Health

Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health.

Mechanochemistry toward Organic "Salt" via Integer-Charge-Transfer Cocrystal Strategy for Rapid, Efficient, and Scalable Near-Infrared Photothermal Conversion

Inspired by the concept of ionic charge-transfer complexes for the Mott insulator, integer-charge-transfer (integer-CT) cocrystals are designed for NIR photo-thermal conversion (PTC). With amino-styryl-pyridinium dyes and F4TCNQ (7,7',8,8'-Tetracyano-2,3,5,6-tetrafluoroquinodimethane) serving as donor/acceptor (D/A) units, integer-CT cocrystals, including amorphous stacking "salt" and segregated stacking "ionic crystal", are synthesized by mechanochemistry and solution method, respectively. Surprisingly, the integer-CT cocrystals are self-assembled only through multiple D-A hydrogen bonds (C-H⋅⋅⋅X (X=N, F)). Strong charge-transfer interactions in cocrystals contribute to the strong light-harvesting ability at 200-1500 nm. Under 808 nm laser illumination, both the "salt" and "ionic crystal" display excellent PTC efficiency beneficial from ultrafast (∼2 ps) nonradiative decay of excited states. Thus integer-CT cocrystals are potential candidates for rapid, efficient, and scalable PTC platforms. Especially amorphous "salt" with good photo/thermal stability is highly desirable in practical large-scale solar-harvesting/conversion applications in water environment. This work verifies the validity of the integer-CT cocrystal strategy, and charts a promising path to synthesize amorphous PTC materials by mechanochemical method in one-step.

Chlorin e6-modified iron oxide nanoparticles for photothermal-photodynamic ablation of glioblastoma cells

Introduction: The effective treatment of glioblastoma still remains a great challenge. We herein report the development of chlorin e6 (Ce6)-conjugated iron oxide (Fe3O4-Ce6) nanoparticles for ablation of glioblastoma cells via combining photothermal therapy (PTT) with photodynamic therapy (PDT). Methods: Ce6 was conjugated to the synthesized Fe3O4 nanoparticles to form Fe3O4-Ce6 nanoparticles displaying the optical property of Ce6. Results and discussion: Under 808 nm laser irradiation, Fe3O4-Ce6 nanoparticles generated heat and the temperature increase did not have obvious changes after five cycles of laser irradiation, suggesting their good photothermal effect and photothermal stability. In addition, 660 nm laser irradiation of Fe3O4-Ce6 nanoparticles produced singlet oxygen (1O2) to mediate PDT. The Fe3O4-Ce6 nanoparticles without laser irradiation showed a low cytotoxicity, but they would obviously kill C6 cancer cells after laser irradiation via the combinational effect of PTT and PDT. Fe3O4-Ce6 nanoparticles thus could be used as a nanotherapeutic agent for combinational ablation of glioblastoma cells.

Designing Nonconventional Luminescent Materials with Efficient Emission in Dilute Solutions via Modulation of Dynamic Hydrogen Bonds

Nonconventional luminescent materials (NLMs) which do not contain traditional aromatic chromophores are of great interest due to their unique chemical structures, optical properties, and their potential applications in various areas, such as cellular imaging and chemical sensing. However, most reported NLMs show weak or no emission in dilute solutions, which severely limits their applications. In this work, dynamic hydrogen bonds were utilized to design NLMs with efficient emission in dilute solutions. To further validate the results, polymers P1 and P2 were successfully prepared and investigated. It was found that the luminescence quantum efficiency of P1 and P2 at a concentration of 0.1 mg/mL in water solution was 8.9 and 0.6%, respectively. The high efficiency can be attributed to the fact that polymer P1 has more intra- or intermolecular dynamic hydrogen bonds and other short interactions than P2 in dilute solutions, allowing P1 to achieve the through-space conjugation effect to increase the degree of system conjugation, restrict molecular motion, and decrease nonradiative transitions, which can effectively improve luminescence. In addition, polymer P2 exhibits the characteristics of clustering-triggered emission, excitation wavelength-dependent and concentration-dependent fluorescence properties, excellent photobleaching resistance, low cytotoxicity, and selective recognition of Fe³⁺. The present study investigates the manipulation of luminescence properties of NLMs in dilute solutions through the modulation of dynamic hydrogen bonds. This approach can serve as a semi-empirical technique for designing and building innovative NLMs in the times ahead.

Dual-Targeting Biomimetic Nanomaterials for Photo-/Chemo-/Antiangiogenic Synergistic Therapy

Avoiding the low specificity of phototheranostic reagents at the tumor site is a major challenge in cancer phototherapy. Meanwhile, angiogenesis in the tumor is not only the premise of tumor occurrence but also the basis of tumor growth, invasion, and metastasis, making it an ideal strategy for tumor therapy. Herein, biomimetic cancer cell membrane-coated nanodrugs (mBPP NPs) have been prepared by integrating (i) homotypic cancer cell membranes for evading immune cell phagocytosis to increase drug accumulation, (ii) protocatechuic acid for tumor vascular targeting along with chemotherapy effect, and (iii) near-infrared phototherapeutic agent diketopyrrolopyrrole derivative for photodynamic/photothermal synergetic therapy. The mBPP NPs exhibit high biocompatibility, superb phototoxicity, excellent antiangiogenic ability, and double-trigging cancer cell apoptosis in vitro. More significantly, mBPP NPs could specifically bind to tumor cells and vasculature after intravenous injection, inducing fluorescence and photothermal imaging-guided tumor ablation without recurrence and side effects in vivo. The biomimetic mBPP NPs could cause drug accumulation at the tumor site, inhibit tumor neovascularization, and improve phototherapy efficiency, providing a novel avenue for cancer treatment.

A tumor-microenvironment-activated nanoplatform of modified SnFe2O4 nanozyme in scaffold for enhanced PTT/PDT tumor therapy

Phototherapy has attracted widespread attention for cancer treatment due to its noninvasiveness and high selectivity. However, severe hypoxia, overexpressed glutathione and high levels of hydrogen peroxide (H₂O₂) of tumor microenvironment limit the antitumor efficiency of phototherapy. Herein, inspired by the specific response of nanozymes to the tumor microenvironment, a simple and versatile nanozyme-mediated synergistic dual phototherapy nanoplatform is constructed. In this study, tin ferrite (SnFe₂O₄, SFO) nanozyme as a photosensitizer was surface modified with polydopamine (denoted as P-SFO) and incorporated into poly(l-lactide) to fabricate an antitumor scaffold fabricated by selective laser sintering. On one hand, SFO nanozyme could act as a photoabsorber to convert light energy into heat for photothermal therapy (PTT). On the other hand, it played a role of photosensitizer in transferring the photon energy to generate reactive oxygen species (ROS) for photodynamic therapy (PDT). Importantly, its multivalent metal ions redox couples would decompose H₂O₂ into O₂ for enhancing O₂-dependent PDT and consume glutathione to relieve antioxidant capability of the tumors. Besides, polydopamine as a photothermal conversion agent further enhanced the photothermal performance of SFO. The results revealed the PLLA/P-SFO scaffold possessed a photothermal conversion efficiency of 43.52% for PTT and a high ROS generation capacity of highly toxic ·O₂^- and ·OH for PDT. Consequently, the scaffold displayed a prominent phototherapeutic effect with antitumor rate of 96.3%. In addition, the PLLA/P-SFO scaffolds possessed good biocompatibility for cell growth. These advantages endow PLLA/P-SFO scaffold with extensive applications in biomedical fields and opened up new avenue towards nanozyme-mediated synergistic phototherapy.

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.

Recent Advances of Diketopyrrolopyrrole Derivatives in Cancer Therapy and Imaging Applications

Cancer is threatening the survival of human beings all over the world. Phototherapy (including photothermal therapy (PTT) and photodynamic therapy (PDT)) and bioimaging are important tools for imaging-mediated cancer theranostics. Diketopyrrolopyrrole (DPP) dyes have received more attention due to their high thermal and photochemical stability, efficient reactive oxygen species (ROS) generation and thermal effects, easy functionalization, and tunable photophysical properties. In this review, we outline the latest achievements of DPP derivatives in cancer therapy and imaging over the past three years. DPP-based conjugated polymers and small molecules for detection, bioimaging, PTT, photoacoustic imaging (PAI)-guided PTT, and PDT/PTT combination therapy are summarized. Their design principles and chemical structures are highlighted. The outlook, challenges, and future opportunities for the development of DPP derivatives are also presented, which will give a future perspective for cancer treatment.

A hypoxia-activatable theranostic agent with intrinsic endoplasmic reticulum affinity and type-I photosensitivity

A unique photosensitizer (PS), ERPS, with intrinsic endoplasmic reticulum (ER)-targeting ability and low oxygen-depletion type-I photosensitivity, is developed and used as a scaffold to construct an activatable theranostic agent for precise photodynamic therapy (PDT). The ER-targeted feature coupled with type-I photosensitivity endows ERPS with high phototoxicity toward tumor cells under both normoxic and hypoxic conditions. In addition, caging the phenol group of ERPS with a nitroreductase-sensitive triggering group provided a hypoxia-activatable PS (ERPSIm) that is encapsulated within a polymeric micelle to obtain a water-stable Im@NP nanoparticle for in vivo applications. After intravenous administration to 4T1 tumor-bearing BALB/c mice, Im@NP demonstrated highly efficient imaging-guided PDT ablation of implanted tumors. This is because the delivered ERPSIm cargos of Im@NP are specifically activated in the hypoxic microenvironment of solid tumor, and the activated ERPS molecules have efficient ER-targeted type-I photosensitivity.

Oxidization enhances type I ROS generation of AIE-active zwitterionic photosensitizers for photodynamic killing of drug-resistant bacteria

Type I photosensitizers (PSs) with an aggregation-induced emission (AIE) feature have received sustained attention for their excellent theranostic performance in the treatment of clinical diseases. However, the development of AIE-active type I PSs with strong reactive oxygen species (ROS) production capacity remains a challenge due to the lack of in-depth theoretical studies on the aggregate behavior of PSs and rational design strategies. Herein, we proposed a facile oxidization strategy to enhance the ROS generation efficiency of AIE-active type I PSs. Two AIE luminogens, MPD and its oxidized product MPD-O were synthesized. Compared with MPD, the zwitterionic MPD-O showed higher ROS generation efficiency. The introduction of electron-withdrawing oxygen atoms results in the formation of intermolecular hydrogen bonds in the molecular stacking of MPD-O, which endowed MPD-O with more tightly packed arrangement in the aggregate state. Theoretical calculations demonstrated that more accessible intersystem crossing (ISC) channels and larger spin-orbit coupling (SOC) constants provide further explanation for the superior ROS generation efficiency of MPD-O, which evidenced the effectiveness of enhancing the ROS production ability by the oxidization strategy. Moreover, DAPD-O, a cationic derivative of MPD-O, was further synthesized to improve the antibacterial activity of MPD-O, showing excellent photodynamic antibacterial performance against methicillin-resistant S. aureus both in vitro and in vivo. This work elucidates the mechanism of the oxidization strategy for enhancing the ROS production ability of PSs and offers a new guideline for the exploitation of AIE-active type I PSs.

Cooperative phototherapy based on bimodal imaging guidance for the treatment of uveal melanoma

BACKGROUND

Uveal melanoma (UM) is adults' most common primary intraocular malignant tumor, prone to metastasis and high mortality. Eyeball enucleation commonly used in the clinic will lead to permanent blindness and mental disorders. Thus, new methods are urgently needed to diagnose and treat UM early to preserve patients' vision.

METHODS AND RESULTS

Herein, multifunctional nanoparticles (NPs) were synthesized by loading chlorin e6 (Ce6) in poly-lactic-co-glycolic acid (PLGA) NPs and wrapping Fe^III-tannic acid (Fe^III-TA) on the outside (Fe^III-TA/PLGA/Ce6, designated as FTCPNPs). Then, the synergistic photothermal therapy (PTT) and photodynamic therapy (PDT) antitumor effects of FTCPNPs excited by near-infrared (NIR) laser were evaluated. Moreover, we verified the mechanism of synergistic PTT/PDT leading to mitochondrial dysfunction and inducing tumor cell apoptosis. Additionally, FTCPNPs can be used as excellent magnetic resonance (MR)/photoacoustic (PA) imaging contrast agents, enabling imaging-guided cancer treatment. Finally, The NPs have good biological safety.

CONCLUSION

This noninvasive NIR light-triggered cooperative phototherapy can easily penetrate eye tissue and overcome the disadvantage of limited penetration of phototherapy. Therefore, cooperative phototherapy is expected to be used in fundus tumors. This treatment model is applied to UM for the first time, providing a promising strategy and new idea for integrating the diagnosis and treatment of UM.

BODIPY-Functionalized Natural Polymer Coatings for Multimodal Therapy of Drug-Resistant Bacterial Infection

The fact that multidrug resistance (MDR) could induce medical device-related infections, along with the invalidation of traditional antibiotics has become an intractable global medical issue. Therefore, there is a pressing need for innovative strategies of antibacterial functionalization of medical devices. For this purpose, a multimodal antibacterial coating that combines photothermal and photodynamic therapies (PTT/PDT) is developed here based on novel heavy atom-free photosensitizer compound, BDP-6 (a kind of boron-dipyrromethene). The photothermal conversion efficiency of BDP-6 is of 55.9%, which could improve biocompatibility during PTT/PDT process by reducing the exciting light power density. Furthermore, BDP-6, together with oxidized hyaluronic acid, is crosslinked with a natural polymer, gelatin, to fabricate a uniform coating (denoted as polyurethane (PU)-GHB) on the surface of polyurethane. PU-GHB has excellent synergistic in vitro PTT/PDT antibacterial performance against both susceptible bacteria and MDR bacteria. The antibacterial mechanisms are revealed as that hyperthermia could reduce the bacterial activity and enhance the permeability of inner membrane to reactive oxygen species by disturbing cell membrane. Meanwhile, in an infected abdominal wall hernia model, the notable anti-infection performance, good in vivo compatibility, and photoacoustic imaging property of PU-GHB are verified. A promising strategy of developing multifunctional antibacterial coatings on implanted medical devices is provided here.

Photothermal-accelerated urease-powered human serum albumin nanomotor for rapid and efficient photothermal and photodynamic cancer combination therapy

Nanomotors, as a new type of micro-device, show good performance in terms of rapid transportation and deep penetration through their autonomous motion. However, their ability to efficiently break physiological barriers still remains a great challenge. Herein, we first developed a thermal-accelerated urease driven human serum albumin (HSA) nanomotor based on photothermal intervention (PTI) to achieve chemotherapy drugfree-phototherapy. The HANM@FI (HSA-AuNR@FA@Ur@ICG) is composed of a main body of biocompatible HSA, modified by gold nanorods (AuNR) and loaded with functional molecules of folic acid (FA) and indocyanine green (ICG). It promotes its own motion by breaking down urea to produce carbon dioxide and ammonia. In particular, the nanomotor is conveniently operated via near-infrared combined photothermal therapy (PTT)/ photodynamic therapy (PDT) to achieve an accelerated De value from 0.73 μm²s^-1 to 1.01μm²s^-1, and ideal tumor ablation at the same time. In contrast to customary urease-driven nanodrug-stacked engine, this HANM@FI has both targeting and imaging-guided capabilities, and finally achieves superior anti-tumor effects without chemotherapy drugs, through a "two-in-one" (motor mobility plus unique phototherapy in chemotherapy-drugfree phototherapy) strategy. This PTI effect with urease-driven nanomotors may offer further possibilities for future clinical applications of nanomedicines by enabling deep penetration and a subsequent chemotherapy-drugfree combination therapy strategy.