A Cascade Strategy Boosting Hydroxyl Radical Generation with Aggregation-Induced Emission Photosensitizers-Albumin Complex for Photodynamic Therapy

Tumor Microenvironment Cascade Activated Biodegradable Nano-Enzymes for Glutathione-Depletion and Ultrasound-Enhanced Chemodynamic Therapy

Chemodynamic therapy (CDT) is emerged as a novel and promising tumor therapy by using the powerful reactive oxygen species (ROS) to kill cancer cells. However, the current CDT is remarkably inhibited due to insufficient H2O2 supply and over-expression of glutathione (GSH) in the tumor microenvironment (TME). Herein, a biodegradable self-supplying H2O2 nano-enzyme of CuO2@CaP with a GSH-consumption effect is designed for cascade enhanced CDT to overcome the problem of H2O2 deficiency and GSH overexpression. In this design, CuO2@CaP is gradually degraded to Ca2+, Cu2+, and H2O2 in acidic TME, resulting in synergistically enhanced CDT owing to the efficient self-supplied H2O2 and GSH-depletion and Ca2+ overload therapy. Interestingly, the faster degradation of CuO2@CaP and promoted production rate of •OH are further achieved after triggering with ultrasound (US). And, the US-enhanced CDT and Ca2+ overload synergistic antitumor therapy is successfully achieved in vivo. These findings provide a promising strategy for designing biodegradable nano-enzymes with self-supplying H2O2 and GSH consumption for US-mediated CDT.

Water-soluble AIE photosensitizer in short-wave infrared region for albumin-enhanced and self-reporting phototheranostics

Organic photosensitizers (PSs) play important roles in phototheranostics, and contribute to the fast development of precision medicine. However, water-soluble and highly emissive organic PSs, especially those emitting in the short-wave infrared region (SWIR), are still challenging. Also, it's difficult to prepare self-reporting PSs for visualizing the treatment via stimulated emission depletion (STED) nanoscopy. Thus, in this work, a water-soluble molecule of DTPAP-TBZ-I with aggregation-induced emission features is designed for the self-reporting photodynamic therapy (PDT) in an ultra-high resolution. In contrast to single molecule, its complex (DTPAP-TBZ-I@BSA) shows much enhanced fluorescence properties and reactive oxygen species (ROS) generation in SWIR window. Their photoluminescence quantum yield is determined to be ∼20.6 % and the enhancement of ROS generation is ∼18-fold. During the PDT, immigration of the complex from cytoplasm to nucleus is also observed via STED nanoscopy with a resolution of 66.11 nm, which allows self-report in the PDT treatment. DTPAP-TBZ-I@BSA is finally utilized for the imaging-guided PDT in vivo with a tumor inhibition rate of 84 %. This is the first work in albumin-enhanced water-soluble organic PSs in SWIR window for self-reporting phototheranostics at ultra-high resolutions, providing an ideal solution for the next generation of photosensitizers for precise medicine.

Versatile Bovine Serum Albumin as Ingenious Electron Operator-Enhanced Photoelectrochemical Biosensing for Ultrasensitive Detection of miRNA

Bovine serum albumin (BSA) has been widely used in biosensors as a blocking agent. Herein, conformist BSA was first exploited as an ingenious operator to enhance the photocurrent response of (2Z,2'Z)-2,2'-(1,4-phenylene)bis(3-(4-(bis(4-methoxyphenyl)amino)phenyl)acrylonitrile) (TPDCN)-based photoelectrochemical (PEC) platform via manipulating the electron transfer process of the detection system. Concretely, the presence of target molecules triggered catalytic hairpin assembly reaction and subsequently powered terminal deoxynucleotidyl transferase-mediated signal amplification to produce the AgNP@BSA-DNA dendrimer nanostructure. After being treated with HNO3, a large amount of BSA could be released from the dendrimer nanostructure. When they were transferred to the TPDCN-based PEC platform, the photocurrent response of the biosensor was largely enhanced because BSA can manipulate the electrons of TPDCN via a well-matched energy level to form a new electron transfer track. Meanwhile, tryptophan (Trp) in BSA could be oxidized to quinone Trp-O under photoirradiation, which can facilitate the oxidation of ascorbate and generate more H+ to promote the migration of photogenerated electrons. As a result, the proposed PEC biosensor exhibits excellent analytical performance for detection of miRNA-21 (as a model target) over a wide linear range of 0.01 to 10,000 pM with detection limit as low as 4.7 fM. Overall, this strategy provides a new perspective on constructing efficient PEC biosensors, which expands the potential applications in bioanalysis and clinical diagnosis.

Hypoxia-accelerating pyroptosis nanoinducers for promoting image-guided cancer immunotherapy

Precise image-guided cancer immunotherapy holds immense potential in revolutionizing cancer treatment. The strategies facilitating activatable imaging and controlled therapeutics are highly desired yet to be developed. Herein, we report a new pyroptosis nanoinducer that integrates aggregation-induced emission luminogen (AIEgen) and DNA methyltransferase inhibitor with hypoxia-responsive covalent organic frameworks (COFs) for advanced image-guided cancer immunotherapy. We first synthesize and compare three donor-acceptor type AIEgens featuring varying numbers of electron-withdrawing units, and find that the incorporation of two acceptors yields the longest response wavelength and most effective photodynamic therapy (PDT) property, surpassing the performance of analogs with one or three acceptor groups. A COF-based nanoplatform containing AIEgen and pyroptosis drug is successfully constructed via the one-pot method. The intra-COF energy transfer significantly quenches AIEgen, in which both fluorescence and PDT properties greatly enhance upon hypoxia-triggered COF degradation. Moreover, the photodynamic process exacerbates hypoxia, accelerating pyroptosis drug release. The nanoagent enables sensitive delineation of tumor site through in situ activatable fluorescence signature. Thanks to the exceptional ROS production capabilities and hypoxia-accelerating drug release, the nanoagent not only inhibits primary tumor growth but also impedes the progression of distant tumors in 4T1 tumor-bearing mice through potent pyroptosis-mediated immune response. This research introduces a novel strategy for achieving activatable phototheranostics and self-accelerating drug release for synergetic cancer immunotherapy.

Molecular Engineering of Pure Superoxide Radical Photogenerator for Hypoxia-Tolerant Tumor Theranostics

Photodynamic therapy (PDT) is a promising cancer treatment, but limited oxygen supply in tumors (hypoxia) can hinder its effectiveness. This is because traditional PDT relies on Type-II reactions that require oxygen. Type-I photosensitizers (PSs) offer a promising approach to overcome the limitations of tumor photodynamic therapy (PDT) in hypoxic environments. To leverage the advantages of Type-I PDT, the design and evaluation of a series of Type-I PSs for developing pure Type-1 PSs, by incorporating benzene, thiophene, or bithiophene into the donor-acceptor molecular skeleton are reported. Among them, CTTI (with bithiophene) shows the best performance, generating the most superoxide radical (O2 •-) upon light irradiation. Importantly, CTTI exclusively produced superoxide radicals, avoiding the less effective Type-II pathway. This efficiency is due to CTTI's energy gap and low reduction potential, which favor electron transfer to oxygen for O2 •- generation. Finally, CTTI NPs are successfully fabricated by encapsulating CTTI into liposomes, and validated to be effective in killing tumor cells, even under hypoxic conditions, making them promising hypoxia-tolerant tumor phototheranostic agents in both in vitro and in vivo applications.

Optimized Bionic Drug-Delivery-Inducing Immunogenic Cell Death and cGAS-STING Pathway Activation for Enhanced Photodynamic-Chemotherapy-Driven Immunotherapy in Prostate Cancer

Prostate cancer presents as a challenging disease, as it is often characterized as an immunologically "cold" tumor, leading to suboptimal outcomes with current immunotherapeutic approaches in clinical settings. Photodynamic therapy (PDT) harnesses reactive oxygen species generated by photosensitizers (PSs) to disrupt the intracellular redox equilibrium. This process induces DNA damage in both the mitochondria and nucleus, activating the process of immunogenic cell death (ICD) and the cGAS-STING pathway. Ultimately, this cascade of events leads to the initiation of antitumor immune responses. Nevertheless, existing PSs face challenges, including suboptimal tumor targeting, aggregation-induced quenching, and insufficient oxygen levels in the tumor regions. To this end, a versatile bionic nanoplatform has been designed for the simultaneous delivery of the aggregation-induced emission PS TPAQ-Py-PF6 and paclitaxel (PTX). The cell membrane camouflage of the nanoplatform leads to its remarkable abilities in tumor targeting and cellular internalization. Upon laser irradiation, the utilization of TPAQ-Py-PF6 in conjunction with PTX showcases a notable and enhanced synergistic antitumor impact. Additionally, the nanoplatform has the capability of initiating the cGAS-STING pathway, leading to the generation of cytokines. The presence of damage-associated molecular patterns induced by ICD collaborates with these aforementioned cytokines lead to the recruitment and facilitation of dendritic cell maturation. Consequently, this elicits a systemic immune response against tumors. In summary, this promising strategy highlights the use of a multifunctional biomimetic nanoplatform, combining chemotherapy, PDT, and immunotherapy to enhance the effectiveness of antitumor treatment.

Advances in biomimetic AIE nanoparticles for diagnosis and phototherapy

This minireview provides an overview of the recent advancements in the development of biomimetic Aggregation-Induced Emission (AIE) nanoparticles and their applications in disease diagnosis, phototherapy, and photoimmunotherapy. AIE nanoparticles can be engineered to enable efficient image-guided photodynamic and photothermal therapies, however, challenges related to immune defense and target specificity persist. To overcome these, coating biomimetic materials on the surface of AIE nanoparticles, which mimic the features and functions of native cells, have emerged as a promising solution. This minireview will highlight the synthesis strategies and discuss the biomedical application of biomimetic AIE nanoparticles.

Efficient hydroxyl radical generation of an activatable phthalocyanine photosensitizer: oligomer higher than monomer and nanoaggregate

It remains a challenge to develop a single-component organic photosensitizer that efficiently produces hydroxyl radicals (˙OH) without oxygen involvement, especially while maintaining tumor-targeting capability. Herein, we propose an intelligent molecular design strategy whereby a tumor-targeted phthalocyanine is initially ˙OH-free and can be activated by overexpressed β-nicotinamide adenine dinucleotide sodium salt hydrate (NAD(P)H) in hypoxic tumors to efficiently produce ˙OH under light irradiation. Furthermore, the oligomer models based on the phthalocyanine molecules were constructed by a supramolecular regulation strategy, which were in an intermediate state between monomer and nanoaggregate, to achieve enhanced ˙OH generation. The level of NAD(P)H in cancer cells can be exhausted through two pathways, including spontaneous redox and the photocatalytic redox of phthalocyanines. As a result, the in vivo and in vitro assays illustrated that the oligomeric phthalocyanine containing N-O units (OligPcNOB) can specifically target cancer cells and tumor tissue with overexpressing biotin receptors. OligPcNOB exhibited significant photocytotoxicity even in an extremely low oxygen environment and successfully inhibited tumor progression.

TME-Triggered Degradable Phototheranostic Nanoplatform for NIR-II Fluorescence Bioimaging-Guided Phototherapies and Immune Activation

The low therapeutic efficacy and potential long-term toxicity of antitumor treatments seriously limit the clinical application of phototherapies. Herein, we develop a degradable phototheranostic nanoplatform for NIR-II fluorescence bioimaging-guided synergistic photothermal (PTT) and photodynamic therapies (PDT) and immune activation to inhibit tumor growth. The phototheranostic nanoplatform (CX@PSS) consists of multidisulfide-containing polyurethane loaded with a photosensitizer CX, which can be specifically degraded in the GSH overexpressed tumor microenvironment (TME) and exhibits good NIR-II fluorescence, photodynamic, and photothermal properties. Under 808 nm light irradiation, CX@PSS exhibits efficient photothermal conversion and ROS generation, which further induces immunogenic cell death (ICD), releasing tumor-associated antigens and activating the immune response. In vitro and in vivo studies confirm the potential of CX@PSS in NIR II FL imaging-guided tumor treatments by synergistic PTT, PDT, and immune activation. This work is expected to provide a new pathway for clinical applications of imaging-guided tumor diagnosis and treatments.

Manipulation of Nonradiative Process Based on the Aggregation Microenvironment to Customize Excited-State Energy Conversion

ConspectusNonradiative processes with the determined role in excited-state energy conversion, such as internal conversion (IC), vibrational relaxation (VR), intersystem crossing (ISC), and energy or electron transfer (ET or eT), have exerted a crucial effect on biological functions in nature. Inspired by these, nonradiative process manipulation has been extensively utilized to develop organic functional materials in the fields of energy and biomedicine. Therefore, comprehensive knowledge and effective manipulation of sophisticated nonradiative processes for achieving high-efficiency excited-state energy conversion are quintessential. So far, many strategies focused on molecular engineering have demonstrated tremendous potential in manipulating nonradiative processes to tailor excited-state energy conversion. Besides, molecular aggregation considerably affects nonradiative processes due to their ultrasensitivity, thus providing us with another essential approach to manipulating nonradiative processes, such as the famous aggregation-induced emission. However, the weak interactions established upon aggregation, namely, the aggregation microenvironment (AME), possess hierarchical, dynamic, and systemic characteristics and are extremely complicated to elucidate. Revealing the relationship between the AME and nonradiative process and employing it to customize excited-state energy conversion would greatly promote advanced materials in energy utilization, biomedicine, etc., but remain a huge challenge. Our group has devoted much effort to achieving this goal.In this Account, we focus on our recent developments in nonradiative process manipulation based on AME. First, we provide insight into the effect of the AME on nonradiative process in terms of its steric effect and electronic regulation, illustrating the possibility of nonradiative process manipulation through AME modulation. Second, the distinct enhanced steric effect is established by crystallization and heterogeneous polymerization to conduct crystallization-induced reversal from dark to bright excited states and dynamic hardening-triggered nonradiative process suppression for highly efficient luminescence. Meanwhile, promoting the ISC process and stabilizing the triplet state are also manipulated by the crystal and polymer matrix to induce room-temperature phosphorescence. Furthermore, the strategies employed to exploit nonradiative processes for photothermy and photosensitization are reviewed. For photothermal conversion, besides the weakened steric effect with promoted molecular motions, a new strategy involving the introduction of diradicals upon aggregation to narrow the energy band gap and enhance intermolecular interactions is put forward to facilitate IC and VR for high-efficiency photothermal conversion. For photosensitization, both the enhanced steric effect from the rigid matrix and the effective electronic regulation from the electron-rich microenvironment are demonstrated to facilitate ISC, ET, and eT for superior photosensitization. Finally, we explore the existing challenges and future directions of nonradiative process manipulation by AME modulation for customized excited-state energy conversion. We hope that this Account will be of wide interest to readers from different disciplines.

Multimodal phototherapy agents target lipid droplets for near-infrared imaging-guided type I photodynamic/photothermal therapy

The construction and optimization of a single phototherapeutic agent with photoluminescence, type I photodynamic therapy (PDT), and photothermal therapy (PTT) functions remain challenging. In this study, we aimed to design and synthesize four donor-acceptor (D-A) type aggregation-induced emission molecules: PSI, TPSI, PSSI, and TPSSI. We employed phenothiazine as an electron donor and 1,3-bis(dicyanomethylidene)indan as a strong electron acceptor in the synthesis process. Among them, TPSSI exhibited efficient type I reactive oxygen species generation, high photothermal conversion efficiency (45.44 %), and near-infrared emission. These observations can be attributed to the introduction of a triphenylamine electron donor group and a thiophene unit, which resulted in increased D-A strengths, a reduced singlet-triplet energy gap, and increased free intramolecular motion. TPSSI was loaded into bovine serum albumin to prepare biocompatible TPSSI nanoparticles (NPs). Our results have indicated that TPSSI NPs can target lipid droplets with negligible dark toxicity and can efficiently generate O2•- in hypoxic tumor environments. Moreover, TPSSI NPs selectively targeted 4T1 tumor tissues and exhibited a good PDT-PTT synergistic effect in vitro and in vivo. We believe that the successful preparation of multifunctional phototherapeutic agents will promote the development of efficient tumor diagnosis and treatment technologies. STATEMENT OF SIGNIFICANCE: The construction of a single phototherapeutic agent with photoluminescence, type I photodynamic therapy, and photothermal therapy functions, and its optimization remain challenging. In this study, we construct four donor-acceptor aggregation-induced emission molecules using phenothiazine as an electron donor and 1,3-Bis(dicyanomethylidene)indan as a strong electron acceptor. By optimizing the molecular structure, an integrated phototherapy agent with fluorescence imaging ability and high photodynamic / photothermal therapy performance was prepared. We believe that the successful preparation of multifunctional phototherapeutic agents will promote the development of efficient tumor diagnosis and treatment technology.

Mitoxantrone encapsulated photosensitizer nanomicelle as carrier-free theranostic nanomedicine for near-infrared fluorescence imaging-guided chemo-photodynamic combination therapy on cancer

Combination therapy exhibits higher efficacy than any single therapy, inspiring various nanocarrier-assisted multi-drug co-delivery systems for the combined treatment of cancer. However, most nanocarriers are inert and non-therapeutic and have potential side effects. Herein, an amphiphilic polymer composed of a hydrophobic photosensitizer and hydrophilic poly(ethylene glycol) was employed as the nanocarriers and photosensitizers to encapsulate the chemotherapeutic drug mitoxantrone for chemo-photodynamic combination therapy. The resulting nanodrug consisted solely of pharmacologically active ingredients, thus avoiding potential toxicity induced by inert excipients. This multifunctional nanoplatform demonstrated significantly superior treatment performance compared to monotherapy for colorectal cancer, both in vitro and in vivo, achieving near-infrared fluorescence imaging-mediated chemo-photodynamic combined eradication of malignancy.

Type-I Photodynamic Therapy Induced by Pt-Coordination of Type-II Photosensitizers into Supramolecular Complexes

Platinum supramolecular complexes based on photosensitizers have garnered great interest in photodynamic therapy (PDT) due to Pt (II) centers as chemotherapeutic agents to eliminate tumor cells completely, which greatly improve the antitumor efficacy of PDT. However, in comparison to precursor photosensitizer ligand, the formed platinum supramolecular complexes typically exhibit inferior outcomes in terms of reactive oxygen species (ROS) generation. How to boost ROS generation in the formed platinum supramolecular complexes for enhanced PDT is an enticing yet highly challenging task. Here we report a Pt-coordination-based dimeric photosensitizer complex (Cz-BTZ-Py)2Pt(OTf)2. It is found that comparing with photosensitizer ligand Cz-BTZ-Py, the formed supramolecular complex exhibit redshifts of absorption wavelength as well as enhanced ROS generation efficiency. Moreover, type-I ROS generation (O2⋅-) is produced in the formed platinum supramolecular complexes mainly due to a reduced energy gap ΔEST resulting from exciton coupling between two photosensitizer ligands. And type-I ROS (O2⋅-) generation significantly amplifies the photodynamic therapy (PDT) outcomes. In vitro evaluation shows excellent photochemotherapy performance of (Cz-BTZ-Py)2Pt(OTf)2 nanoparticles. We anticipate this work would provide a novel approach to design type-I photosensitizers for efficient PDT.

Mechanistic analysis of viscosity-sensitive fluorescent probes for applications in diabetes detection

Diabetes is one of the most detrimental diseases affecting the human life because it can initiate several other afflictions such as liver damage, kidney malfunctioning, and cardiac inflammation. The primary method for diabetes diagnosis involves the analysis of blood samples to quantify the level of glucose, while secondary diagnostic methods involve the qualitative analysis of obesity, fatigue, etc. However, all these symptoms start showing up only when the patient has been suffering from diabetes for a certain period of time. In order to avoid such delay in diagnosis, the development of specific fluorescent probes has attracted considerable attention. Prominent biomarkers for diabetes include abundance of certain analytes in blood serum, e.g., glucose, methylglyoxal, albumin, and reactive oxygen species; high intracellular viscosity; alteration of enzyme functionality, etc. Among these, high viscosity can greatly affect the fluorescence properties of various chromophores owing to the environment sensitivity of fluorescence spectra. In this review article, we have illustrated the application of some prominent fluorophores such as coumarin, BODIPY, xanthene, and rhodamine in the development of viscosity-dependent fluorescent probes. Detailed mechanistic aspects determining the influence of viscosity on the fluorescent properties of the probes have also been elaborated. Fluorescence mechanisms that are directly affected by the high-viscosity heterogeneous microenvironment are based on intramolecular rotations like twisted intramolecular charge transfer (TICT), aggregation-induced emission (AIE), and through-bond energy transfer (TBET). In this regard, this review article will be highly useful for researchers working in the field of diabetes treatment and fluorescent probes. It also provides a platform for the planning of futuristic clinical translation of fluorescent probes for the early-stage diagnosis and therapy of diabetes.

Conformational Isomerization Effect on Singlet/Triplet Energy Consumption Process of Thermally Activated Delayed Fluorescence Molecules with Aggregation Induced Emission: A QM/MM Study

Thermally activated delayed fluorescence (TADF) molecules with aggregation-induced emission (AIE) properties hold tremendous potential in biomedical sensing/imaging and telecommunications. In this study, a multiscale method combined with thermal vibration correlation function (TVCF) theory is used to investigate the photophysical properties of the novel TADF molecule CNPy-SPAC in toluene and crystal and amorphous states. In the crystal state, an increase in radiative rates and a decrease in nonradiative rates lead to AIE. Additionally, conformational isomerization effects result in significantly different luminescent efficiencies between the two crystal structures. Furthermore, the isomerization effect allows for the coexistence of three configurations in the amorphous state. Among them, the non-TADF quasi-axial (Qa) configuration may facilitate energy transfer to the TADF-characteristic quasi-equal/quasi-equal-H (Qe/Qe-H) configurations, enhancing AIE. Moreover, the Qa configuration enables rapid electron transport, offering the potential for self-doped devices. Our work elucidates a new mechanism for the isomerization effect in AIE-TADF molecules.