Photosensitizer synergistic effects: D-A-D structured organic molecule with enhanced fluorescence and singlet oxygen quantum yield for photodynamic therapy

A supramolecular photosensitizer based on triphenylamine and pyrazine with aggregation-induced emission properties for high-efficiency photooxidation reactions

Recently, there has been a great interest in the study of photocatalysts (PCs) and photosensitizers (PSs) in the field of organic photocatalysis. In the present study, a pure organic thermally activated delayed fluorescence (TADF) molecule 4,4'-(12-(pyridin-4-yl)dibenzo[f,h]pyrido[2,3-b]quinoxaline-3,6-diyl)bis(N,N-diphenylaniline) (DPQ-TPA) was designed and synthesized, which not only have excellent TADF property and small energy splitting (ΔEST), but also can self-assembly in water to form cross-linked nanoparticles with exceptional aggregation-induced emission (AIE) characteristics. DPQ-TPA exhibits excellent remarkable selectivity and notably enhances the production capacity of reactive oxygen species (ROS), particularly 1O2, which was employed as a highly effective photocatalyst in the photooxidation reaction of phosphine and hydroazobenzenes under blue light irradiation with high yields up to 94% and 91%, respectively. This work expands the potential application of (donor-acceptor) D-A type AIE-TADF molecules in photocatalytic organic transformations through supramolecular self-assembly.

Immunological nanomaterials to combat cancer metastasis

Metastasis causes greater than 90% of cancer-associated deaths, presenting huge challenges for detection and efficient treatment of cancer due to its high heterogeneity and widespread dissemination to various organs. Therefore, it is imperative to combat cancer metastasis, which is the key to achieving complete cancer eradication. Immunotherapy as a systemic approach has shown promising potential to combat metastasis. However, current clinical immunotherapies are not effective for all patients or all types of cancer metastases owing to insufficient immune responses. In recent years, immunological nanomaterials with intrinsic immunogenicity or immunomodulatory agents with efficient loading have been shown to enhance immune responses to eliminate metastasis. In this review, we would like to summarize various types of immunological nanomaterials against metastasis. Moreover, this review will summarize a series of immunological nanomaterial-mediated immunotherapy strategies to combat metastasis, including immunogenic cell death, regulation of chemokines and cytokines, improving the immunosuppressive tumour microenvironment, activation of the STING pathway, enhancing cytotoxic natural killer cell activity, enhancing antigen presentation of dendritic cells, and enhancing chimeric antigen receptor T cell therapy. Furthermore, the synergistic anti-metastasis strategies based on the combinational use of immunotherapy and other therapeutic modalities will also be introduced. In addition, the nanomaterial-mediated imaging techniques (e.g., optical imaging, magnetic resonance imaging, computed tomography, photoacoustic imaging, surface-enhanced Raman scattering, radionuclide imaging, etc.) for detecting metastasis and monitoring anti-metastasis efficacy are also summarized. Finally, the current challenges and future prospects of immunological nanomaterial-based anti-metastasis are also elucidated with the intention to accelerate its clinical translation.

Recent Advances in Photosensitizer Materials for Light-Mediated Tumor Therapy

Photodynamic therapy (PDT) as an emerging therapeutic method has drawn much attention in the treatment field for cancer. Photosensitizer, which can convert photon energy into cytotoxic species under light irradiation, is the core component in PDT. The design of photosensitizers still faces problems of light absorption, targeting, penetration and oxygen dependence. With the rapid progress of material science, various photosensitizers have been developed to produce cytotoxic species for treatment of tumor with high selectivity, safety, and noninvasiveness. Besides, the applications of photosensitizers have been expanded to diverse cancer treatments such as drug release, optogenetics and immune checkpoint blockade. In this review, we summarize the recent advances of photosensitizers in various therapeutic methods for cancer. Prevailing challenges and further prospects associated with photosensitizers are also discussed.

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.

Nanoplatform-based strategies for enhancing the lethality of current antitumor PDT

Photodynamic therapy (PDT) exhibits great application prospects in future clinical oncology due to its spatiotemporal controllability and good biosafety. However, the antitumor efficacy of PDT is seriously hindered by many factors, including tumor hypoxia, limited light penetration ability, and strong defense mechanisms of tumors. Considering that it is difficult to completely solve the first two problems, enhancing the lethality of antitumor PDT has become a good idea to extend its clinical application. Herein, we summarize the nanoplatform-involved strategies to effectively amplify the tumoricidal capability of current PDT and then discuss the present bottlenecks and prospects of the nanoplatform-based PDT sensitization strategies in tumor therapy. We hope this review will provide some references for others to design high-performance PDT nanoplatforms for tumor therapy.

Reusable and self-sterilization mask for real-time personal protection based on sunlight-driven photocatalytic reaction

Personal protective masks play critical role in preventing the disease epidemic and resisting pathogenic bacterial infestation. However, large quantities of masks were disposed during COVID-19 epidemic, which caused environmental problem and huge economic burden. Herein, we developed reusable masks with inherent antimicrobial and self-cleaning features under solar irradiation. With spun-bonded nonwoven fabrics (SNF) layer as substrate, copper sulfide@polydopamine nanoparticles are deposited on SNF layer (CuS@PDANPs-SNF), which presents excellent photocatalytic activity. Under solar irradiation, CuS@PDANPs produce abundant of singly linear oxygen (1O2), which inactivates pathogenic bacteria with high efficiency over 99%. Interestingly, CuS@PDANPs-SNF cannot cause high temperature to bring any uncomfortable to the person, which is suitable for human to wear in daily life. Such design effectively protect person from the transmission of viral aerosol. Meanwhile, CuS@PDANPs-SNF masks are reusable and still maintain robust bactericidal ability after washing. The sunlight-mediated self-sterilization at low temperature endows CuS@PDANPs-SNF masks as powerful personal protective equipment for daily protection, which also provides an instructive way for reducing the environmental impact.

Combining Multiple Photosensitizer Modules into One Supramolecular System for Synergetic Enhanced Photodynamic Therapy

Photodynamic therapy (PDT), as an emerging cancer treatment, requires the development of highly desirable photosensitizers (PSs) with integrated functional groups to achieve enhanced therapeutic efficacy. Coordination-driven self-assembly (CDSA) would provide an alternative approach for combining multiple PSs synergistically. Here, we demonstrate a simple yet powerful strategy of combining conventional chromophores (tetraphenylethylene, porphyrin, or Zn-porphyrin) with pyridinium salt PSs together through condensation reactions, followed by CDSA to construct a series of novel metallo-supramolecular PSs (S1-S3). The generation of reactive oxygen species (ROS) is dramatically enhanced by the direct combination of two different PSs, and further reinforced in the subsequent ensembles. Among all the ensembles, S2 with two porphyrin cores shows the highest ROS generation efficiency, specific interactions with lysosome, and strong emission for probing cells. Moreover, the cellular and living experiments confirm that S2 has excellent PDT efficacy, biocompatibility, and biosafety. As such, this study will enable the development of more efficient PSs with potential clinical applications.

Enhancing near-infrared II photodynamic therapy with nitric oxide for eradicating multidrug-resistant biofilms in deep tissues

Nitric oxide (NO) enhanced photodynamic therapy (PDT) is a promising approach to overcome drug tolerance and resistance to biofilm but is limited by its short excitation wavelengths and low yield of reactive oxygen species (ROS). Herein, we develop a compelling degradable polymer-based near-infrared II (NIR-II, 1000-1700 nm) photosensitizer (PNIR-II), which can maintain 50 % PDT efficacy even under a 2.6 cm tissue barrier. Remarkably, PNIR-II is synthesized by alternately connecting the electron donor thiophene to the electron acceptors diketopyrrolopyrrole (DPP) and boron dipyrromethene (BODIPY), where the intramolecular charge transfer properties can be tuned to increase the intersystem crossover rate and decrease the internal conversion rate, thereby stabilizing the NIR-II photodynamic rather than photothermal effect. For exerting a combination therapy to eradicate multidrug-resistant biofilms, PNIR-II is further assembled into nanoparticles (NPs) with a synthetic glutathione-triggered NO donor polymer. Under 1064 nm laser radiation, NPs precisely release ROS and NO that triggered by over-expressed GSH in the biofilm microenvironment, thereby forming more bactericidal reactive nitrogen species (RNS) in vitro and in vivo in the mice model that orderly destroy biofilm of multidrug-resistant Staphylococcus aureus cultures from clinical patients. It thus provides a new outlook for destroy the biofilm of deep tissues.

Multifunctional agents based on 3-dicycanovinylindan-1-one acceptor: Molecular design and phototheranostic application

Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has garnered considerable attention in recent years, owing to its precise spatiotemporal accuracy with minimal side effects. Recent research reveals that the combination of PDT and PTT exhibits a remarkable anti-tumor efficacy compared to PDT or PTT alone, which has put forward the new requirements of multifunctional phototherapy agents with both high photosensitization and photothermal conversion efficiencies. Among the newly developed multifunctional agents, the ones with one or two 3-dicycanovinylindan-1-one (IC) moieties as the acceptors attract much more attention, due to their long-wavelength excitation and emission, as well as high phototherapy efficacies. Therefore, in this review, the latest advancement of multifunctional agents based on IC acceptor is summarized. Especially, we focus on the structure-property relationships of the agents, as well as their biomedical application in anti-tumor therapy or image-guided therapy. Our perspective on the further future development of this field is also discussed to conclude.

Synthesis, and evaluation of photophysical properties of a potential DPP-derived photosensitizer for photodynamic therapy with D-A-D architecture

The study of a macromolecule derived from DPP and triphenylamine, (DPP-BisTPA) by computational chemistry, its synthesis by direct arylation, optical characterization (UV-Vis and fluorescence) and electrochemistry (cyclic voltammetry), as well as its evaluation as a generator of reactive oxygen species indirectly, through the degradation of uric acid. The results obtained by DFT using B3LYP/6-31G (d, p) and TD-DFT using CAM-B3LYP/6-31G (d, p) reveal values of energy levels of the first singlet and triplet excited state that indicate a possible intersystem crossover and the possible generation of reactive oxygen species by a type I mechanism. The compound presents an absorption region within the phototherapeutic window. The electrochemical bandgap is 1.64 eV which suggests a behavior as a semiconductor. DPP-BisTPa were processed as hemispherical nanoparticles with a size around 100 nm, and NPOs were evaluated as a photosensitizer with a ROS generation yield of 4% using a photodynamic therapy flashlight as the light source.

Heterogeneity of dispersed species in nickel-loaded carbon-based catalysts for near-infrared photoresponsive synergistic antimicrobial therapy

The development of novel efficient, safe antimicrobial strategies is an urgent need, as the misuse of antibiotics has become a significant threat to human health. Therefore, we have loaded metal Ni with environmentally friendly carbon black as a substrate, with species varying from single atoms to nanoclusters and nanoparticles. The results obtained from the antimicrobial systems and the role of different types of metal species in the photosensitized antimicrobial reactions were compared to better understand the catalytic behavior of different metal entities (single atoms, nanoclusters, and nanoparticles). Furthermore, the antimicrobial mechanisms of these materials were described by physical and chemical characterization, biological experiments, and theoretical calculations. Such systematic studies provide new ideas and prospects for developing more efficient and environmentally friendly antimicrobial materials.

Graphene Oxide/Cholesterol-Substituted Zinc Phthalocyanine Composites with Enhanced Photodynamic Therapy Properties

In the present work, cholesterol (Chol)-substituted zinc phthalocyanine (Chol-ZnPc) and its composite with graphene oxide (GO) were prepared for photodynamic therapy (PDT) applications. Briefly, Chol-substituted phthalonitrile (Chol-phthalonitrile) was synthesized first through the substitution of Chol to the phthalonitrile group over the oxygen bridge. Then, Chol-ZnPc was synthesized by a tetramerization reaction of Chol-phthalonitrile with ZnCl2 in a basic medium. Following this, GO was introduced to Chol-ZnPc, and the successful preparation of the samples was verified through FT-IR, UV-Vis, 1H-NMR, MALDI-TOF MS, SEM, and elemental analysis. Regarding PDT properties, we report that Chol-ZnPc exhibited a singlet oxygen quantum yield (Φ∆) of 0.54, which is slightly lower than unsubstituted ZnPc. Upon introduction of GO, the GO/Chol-ZnPc composite exhibited a higher Φ∆, about 0.78, than that of unsubstituted ZnPc. Moreover, this enhancement was realized with a simultaneous improvement in fluorescence quantum yield (ΦF) to 0.36. In addition, DPPH results suggest low antioxidant activity in the composite despite the presence of GO. Overall, GO/Chol-ZnPc might provide combined benefits for PDT, particularly in terms of image guidance and singlet oxygen generation.

Fluorescent dyes based on rhodamine derivatives for bioimaging and therapeutics: recent progress, challenges, and prospects

Since their inception, rhodamine dyes have been extensively applied in biotechnology as fluorescent markers or for the detection of biomolecules owing to their good optical physical properties. Accordingly, they have emerged as a powerful tool for the visualization of living systems. In addition to fluorescence bioimaging, the molecular design of rhodamine derivatives with disease therapeutic functions (e.g., cancer and bacterial infection) has recently attracted increased research attention, which is significantly important for the construction of molecular libraries for diagnostic and therapeutic integration. However, reviews focusing on integrated design strategies for rhodamine dye-based diagnosis and treatment and their wide application in disease treatment are extremely rare. In this review, first, a brief history of the development of rhodamine fluorescent dyes, the transformation of rhodamine fluorescent dyes from bioimaging to disease therapy, and the concept of optics-based diagnosis and treatment integration and its significance to human development are presented. Next, a systematic review of several excellent rhodamine-based derivatives for bioimaging, as well as for disease diagnosis and treatment, is presented. Finally, the challenges in practical integration of rhodamine-based diagnostic and treatment dyes and the future outlook of clinical translation are also discussed.

Combination of Two Photosensitisers in Anticancer, Antimicrobial and Upconversion Photodynamic Therapy

Photodynamic therapy (PDT) is a special form of phototherapy in which oxygen is needed, in addition to light and a drug called a photosensitiser (PS), to create cytotoxic species that can destroy cancer cells and various pathogens. PDT is often used in combination with other antitumor and antimicrobial therapies to sensitise cells to other agents, minimise the risk of resistance and improve overall outcomes. Furthermore, the aim of combining two photosensitising agents in PDT is to overcome the shortcomings of the monotherapeutic approach and the limitations of individual agents, as well as to achieve synergistic or additive effects, which allows the administration of PSs in lower concentrations, consequently reducing dark toxicity and preventing skin photosensitivity. The most common strategies in anticancer PDT use two PSs to combine the targeting of different organelles and cell-death mechanisms and, in addition to cancer cells, simultaneously target tumour vasculature and induce immune responses. The use of PDT with upconversion nanoparticles is a promising approach to the treatment of deep tissues and the goal of using two PSs is to improve drug loading and singlet oxygen production. In antimicrobial PDT, two PSs are often combined to generate various reactive oxygen species through both Type I and Type II processes.

Nanomaterials-Based Wound Dressing for Advanced Management of Infected Wound

The effective prevention and treatment of bacterial infections is imperative to wound repair and the improvement of patient outcomes. In recent years, nanomaterials have been extensively applied in infection control and wound healing due to their special physiochemical and biological properties. Incorporating antibacterial nanomaterials into wound dressing has been associated with improved biosafety and enhanced treatment outcomes compared to naked nanomaterials. In this review, we discuss progress in the application of nanomaterial-based wound dressings for advanced management of infected wounds. Focus is given to antibacterial therapy as well as the all-in-one detection and treatment of bacterial infections. Notably, we highlight progress in the use of nanoparticles with intrinsic antibacterial performances, such as metals and metal oxide nanoparticles that are capable of killing bacteria and reducing the drug-resistance of bacteria through multiple antimicrobial mechanisms. In addition, we discuss nanomaterials that have been proven to be ideal drug carriers for the delivery and release of antimicrobials either in passive or in stimuli-responsive manners. Focus is given to nanomaterials with the ability to kill bacteria based on the photo-triggered heat (photothermal therapy) or ROS (photodynamic therapy), due to their unparalleled advantages in infection control. Moreover, we highlight examples of intelligent nanomaterial-based wound dressings that can detect bacterial infections in-situ while providing timely antibacterial therapy for enhanced management of infected wounds. Finally, we highlight challenges associated with the current nanomaterial-based wound dressings and provide further perspectives for future improvement of wound healing.

Phototheranostics for NIR fluorescence image guided PDT/PTT with extended conjugation and enhanced TICT

Introducing donor and acceptor into conjugated system can facilitate the intersystem crossing (ISC) rate to increase the generation of ROS. Twisted intramolecular charge transfer (TICT) state could favor enhance the nonradiative transition and photothermal conversion efficiency (PCE). Herein, diketopyrrolopyrrole (DPP) core functionalized benzene (PDDP), thiophene (TDPP), triphenylamine-conjugated benzene (TPA-PDDP) and thiophene (TPA-TDPP) derivatives were designed and synthesized. Electrochemistry experiments revealed the heavy atom effect and the introduction of triphenylamine reduced the energy level of TPA-TDPP and improved the ability to generate ¹O₂ (¹O₂ QY = 50%). In addition, in the aggregated state, introduction of thiophene, triphenylamine, and long alkyl chains promoted the twisting effect, preventing the intermolecular π-π interaction and enhancing the PCE of TPA-TDPP (38.7%). In vivo fluorescence imaging showed that TPA-TDPP NPs can target the tumor site with the enhanced permeability and retention (EPR) effect and presented excellent synergistic photodynamic/photothermal therapy.

Acene enlargement for absorption red-shifting and photosensitization enhancement of photosensitizers with aggregation-induced emission

Photosensitizers with aggregation-induced emission (AIE PSs) were widely explored in photodynamic therapy. Numerous acceptors but few donors were reported to design AIE PSs. In this study, we developed a new kind of donor that can improve the comprehensive performance of AIE PSs by expanding the π extension of aromatic rings at the end of the triphenylamine group through acene enlargement. The absorption and fluorescence peaks of anthryl-substituted AIE PS are red-shifted by 29 nm and 42 nm; the photosensitization efficiency is enhanced by 1.16 times; the AIE factor is 86.1 and the fluorescence quantum yield is 9.3%. We also demonstrated that the anthryl-based AIE PS can image and ablate cancer cells well both in vitro and in vivo. The anthryl-triphenylamine donor provides an excellent option to design donor-acceptor AIE PSs with high comprehensive performance.

Phototheranostic Agents Based on Nonionic Heptamethine Cyanine for Realizing Synergistic Cancer Phototherapy

Asymmetrical heptamethine cyanine with near-infrared (NIR) absorption is used for photothermal therapy (PTT) of cancer. Aiming to overcome the drawbacks caused by the high temperature of PTT, the development of asymmetrical heptamethine cyanine with photothermal and photodynamic properties is still an attractive strategy. Different from the traditional method of the heavy atom effect, in this work, the carboxyl or sulfonic groups are introduced into the indole ring or branch chain of asymmetrical heptamethine cyanine to afford a series of new phototherapy agents. After being encapsulated by DSPE-PEG₂₀₀₀ , BSS-Et NPs exhibit robust photostability, efficient reactive oxygen species generation (49%), and excellent photothermal conversion efficiency of about 37.6% under 808 nm laser irradiation. BSS-Et NPs possess passive tumor-targeting properties in vivo to not only visualize the tumor by NIR fluorescence imaging but also eliminate the tumor without any recurrence by photodynamic therapy and PTT synergistic therapy under laser irradiation. In addition, benefitting from the characteristics of organic small molecules, they can be metabolized quickly through the liver without inducing toxicity in the whole body. In general, this study provides a new direction for the development of multifunctional phototherapy agents for cancer treatment.

Polymerization-Enhanced Photophysical Performances of AIEgens for Chemo/Bio-Sensing and Therapy

AIE polymers have been extensively researched in the fields of OLEDs, sensing, and cancer treatment since its first report in 2003, which have achieved numerous breakthroughs during the years. In comparison with small molecules, it can simultaneously combine the unique advantages of AIE materials and the polymer itself, to further enhance their corresponding photophysical performances. In this review, we enumerate and discuss the common construction strategies of AIE-active polymers and summarize the progress of research on polymerization enhancing luminescence, photosensitization, and room-temperature phosphorescence (RTP) with their related applications in chemo/bio-sensing and therapy. To conclude, we also discuss current challenges and prospects of the field for future development.

Tuning the Photophysics of Two-Arm Bis[(dimethylamino)styryl]benzene Derivatives by Heterocyclic Substitution

The identification of novel molecular systems with high fluorescence and significant non-linear optical (NLO) properties is a hot topic in the continuous search for new emissive probes. Here, the photobehavior of three two-arm bis[(dimethylamino)styryl]benzene derivatives, where the central benzene was replaced by pyridine, furan, or thiophene, was studied by stationary and time-resolved spectroscopic techniques with ns and fs resolution. The three molecules under investigation all showed positive fluorosolvatochromism, due to intramolecular charge-transfer (ICT) dynamics from the electron-donor dimethylamino groups, and significant fluorescence quantum yields, because of the population of a planar and emissive ICT state stabilized by intramolecular hydrogen-bond-like interactions. The NLO properties (hyperpolarizability coefficient and TPA cross-section) were also measured. The obtained results allowed the role of the central heteroaromatic ring to be disclosed. In particular, the introduction of the thiophene ring guarantees high fluorescent quantum yields irrespective of the polarity of the medium, and the largest hyperpolarizability coefficient because of the increased conjugation. An important and structure-dependent involvement of the triplet state was also highlighted, with the intersystem crossing being competitive with fluorescence, especially in the thiophene derivative, where the triplet was found to significantly sensitize molecular oxygen even in polar environment, leading to possible applications in photodynamic therapy.

Constructing Hypoxia-Tolerant and Host Tumor-Enriched Aggregation-Induced Emission Photosensitizer for Suppressing Malignant Tumors Relapse and Metastasis

Photodynamic immunotherapy is a promising treatment strategy that destroys primary tumors and inhibits the metastasis and relapse of distant tumors. As reactive oxygen species are an intermediary for triggering immune responses, photosensitizers (PSs) that can actively target and efficiently trigger oxidative stress are urgently required. Herein, pyrrolo[3,2-b]pyrrole as an electronic donor is introduced in acceptor-donor-acceptor skeleton PSs (TP-IS1 and TP-IS2) with aggregation-induced emission properties and high absorptivity. Meanwhile, pyrrolo[3,2-b]pyrrole derivatives innovatively prove their ability of type I photoreaction, indicating their promising hypoxia-tolerant advantages. Moreover, M1 macrophages depicting an ultrafast delivery through the cell-to-cell tunneling nanotube pathway emerge to construct TP-IS1@M1 by coating the photosensitizer TP-IS1. Under low concentration of TP-IS1@M1, an effective immune response of TP-IS1@M1 is demonstrated by releasing damage-associated molecular patterns, maturating dendritic cells, and vanishing the distant tumor. These findings reveal insights into developing hypoxia-tolerant PSs and an efficient delivery method with unprecedented performance against tumor metastasis.

Photoactive Red Fluorescent SiO2 Nanoparticles Based on Controlled Methylene Blue Aggregation in Reverse Microemulsions

We present a reverse microemulsion synthesis procedure for incorporating methylene blue (MB), a known FDA-approved type-II red-absorbing photosensitizer and ¹O₂ generator, into the matrix of hydrophobic-core/hydrophilic-shell SiO₂ nanoparticles. Different synthesis conditions were explored with the aim of controlling the entrapped-dye aggregation at high dye loadings in the hydrophobic protective core; minimizing dye aggregation ensured highly efficient photoactive nanoentities for ¹O₂ production. Monitoring the synthesis in real time using UV-vis absorption allowed tracking of the dye aggregation process. In particular, silica nanoparticles (MB@SiO₂ NPs) of ∼50 nm diameter size with a high local entrapped-MB concentration (∼10^-2 M, 1000 MB molecules per NP) and a moderate proportion of dye aggregation were obtained. The as-prepared MB@SiO₂ NPs showed a high singlet oxygen photogeneration efficiency (Φ_Δ = 0.30 ± 0.05), and they can be also considered as red fluorescent probes (Φ_F ∼ 0.02, λ_max ∼ 650 nm). The distinctive photophysical and photochemical characteristics of the synthesized NPs reveal that the reverse microemulsion synthesis procedure offers an interesting strategy for the development of complex theranostic nano-objects for photodynamic therapy.

Applications of nanocomposites based on zeolitic imidazolate framework-8 in photodynamic and synergistic anti-tumor therapy

Due to the limitations resulting from hypoxia and the self-aggregation of photosensitizers, photodynamic therapy (PDT) has not been applied clinically to treat most types of solid tumors. Zeolitic imidazolate framework-8 (ZIF-8) is a common metal-organic framework that has ultra-high porosity, an adjustable structure, good biocompatibility, and pH-induced biodegradability. In this review, we summarize the applications of ZIF-8 and its derivatives in PDT. This review is divided into two parts. In the first part, we summarize progress in the application of ZIF-8 to enhance PDT and realize theranostics. We discuss the use of ZIF-8 to avoid the self-aggregation of photosensitizers, alleviate hypoxia, increase the PDT penetration depth, and combine PDT with multi-modal imaging. In the second part, we summarize how ZIF-8 can achieve synergistic PDT with other anti-tumor therapies, including chemotherapy, photothermal therapy, chemodynamic therapy, starvation therapy, protein therapy, gene therapy, and immunotherapy. Finally, we highlight the challenges that must be overcome for ZIF-8 to be widely applied in PDT. To the best of our knowledge, this is the first review of ZIF-8-based nanoplatforms for PDT.

Heptamethine Cyanine-Loaded Nanomaterials for Cancer Immuno-Photothermal/Photodynamic Therapy: A Review

The development of strategies capable of eliminating metastasized cancer cells and preventing tumor recurrence is an exciting and extremely important area of research. In this regard, therapeutic approaches that explore the synergies between nanomaterial-mediated phototherapies and immunostimulants/immune checkpoint inhibitors have been yielding remarkable results in pre-clinical cancer models. These nanomaterials can accumulate in tumors and trigger, after irradiation of the primary tumor with near infrared light, a localized temperature increase and/or reactive oxygen species. These effects caused damage in cancer cells at the primary site and can also (i) relieve tumor hypoxia, (ii) release tumor-associated antigens and danger-associated molecular patterns, and (iii) induced a pro-inflammatory response. Such events will then synergize with the activity of immunostimulants and immune checkpoint inhibitors, paving the way for strong T cell responses against metastasized cancer cells and the creation of immune memory. Among the different nanomaterials aimed for cancer immuno-phototherapy, those incorporating near infrared-absorbing heptamethine cyanines (Indocyanine Green, IR775, IR780, IR797, IR820) have been showing promising results due to their multifunctionality, safety, and straightforward formulation. In this review, combined approaches based on phototherapies mediated by heptamethine cyanine-loaded nanomaterials and immunostimulants/immune checkpoint inhibitor actions are analyzed, focusing on their ability to modulate the action of the different immune system cells, eliminate metastasized cancer cells, and prevent tumor recurrence.

Near-Infrared multifunctional theranostic agent with Wave-Like aggregates modulated by substituent position effect

Precise design of organic photosensitizers (PSs) promoted the technological innovation for multimodal imaging-guided synergistic therapy. Nonetheless, various group substitution could not only optimize the basic photophysical behavior, but possibly change the aggregate, which handicaps the deep understanding of the "Formula-Aggergete-Property" relationship. Bearing this in mind, herein two isomers, named 6-TDE and 7-TDE, were prepared via substituting position modification. Among them, 6-TDE exhibited the grid-like structure, while 7-TDE presented wavy-like structure. Despite the aggregates were different, 6-TDE and 7-TDE shared common features including partly twisted backbone and non-overlapped-orbit, hence resulting in similar optical physical behavior such as decent extinction coefficient, near-IR emission, large stockes shifts, etc. Meanwhile, though two PSs could both generated Type-I and Type-II ROS, 7-TDE possessed smaller singlet-triplet splitting (ΔE_ST), which exhibited favorable ROS as well as outstanding mitochondrial targeting, achieving efficient photodynamic therapy (PDT) effect. During this process, mitochondrial autophagy could be tracked and observed effectively and in real-time. Moreover, 7-TDE presented outstanding performance in multimodal imaging, including fluorescence imaging (FLI), photoacousticimaging (PAI) and photothermal imaging (PTI). This study enriches the strategy of precise molecular engineering to optimize theranostic agents.

Polymethine dyes for PDT: recent advances and perspectives to drive future applications

It has been proved that the effectiveness of photodynamic therapy (PDT) is closely related to the intrinsic features of the photosensitizer (PS). Over the recent years, several efforts have been devoted to the discovery of novel and more efficient photosensitizers showing higher efficacy and lower side effects. In this context, squaraine and cyanine dyes have been reported to potentially overcome the drawbacks related to the traditional PSs. In fact, squaraines and cyanines are characterized by sharp and intense absorption bands and narrow emission bands with high extinction coefficients typically in the red and near-infrared region, good photo and thermal stability and a strong fluorescent emission in organic solvents. In addition, biocompatibility and low toxicity make them suitable for biological applications. Despite these interesting intrinsic features, their chemical instability and self-aggregation properties in biological media still limit their use in PDT. To overcome these drawbacks, the self-assembly and incorporation into smart nanoparticle systems are forwarded promising approaches that can control their physicochemical properties, providing rational solutions for the limitation of free dye administration in the PDT application. The present review summarizes the latest advances in squaraine and cyanine dyes for PDT application, analyzing the different strategies, i.e.the self-assembly and the incorporation into nanoparticles, to further enhance their photochemical properties and therapeutic potential. The in vivo assessments are still limited, thus further delaying their effective application in PDT.

Carrier-Free Delivery of Ultrasmall π-Conjugated Oligomer Nanoparticles with Photothermal Conversion over 80% for Cancer Theranostics

High-performance photothermal theranostics is urgently desired for cancer therapy because of their good controllability and noninvasive features. The relatively low photothermal conversion efficiency is still at the drawbacks because of the absence of efficient extraneous carriers. Herein, a carrier-free nanomedicine is developed to in vivo self-deliver organic photothermal agents for efficient cancer phototheranostics. By a facile self-assembly strategy, the near-infrared (NIR)-absorbing conjugated oligomer IDIC-4F is fabricated into a carrier-free nanoparticle (DCF-P), showing ultrasmall size of nearly 4.0 nm with a nearly 100% of drug loading capacity. Notably, DCF-P achieves a superhigh photothermal conversion efficiency of 80.5% that is far greater than that of IDIC-4F-loaded nanomicelle DCF-M (57.3%). With the guidance of NIR fluorescence and photoacoustic dual-imaging, it is verified that DCF-P could well achieve tumor-preferential accumulation and retention at 4 h postinjection, and meanwhile shows highly efficient in vivo tumor elimination with good biosafety. This study thus contributes a novel concept for designing ultrasmall nanoparticle characteristics of preferential accumulation in tumors, and also provides a strategy for creating high-performance carrier-free nanomedicine via highly ordered molecular stacking.

Dual-Light-Triggered In Situ Structure and Function Regulation of Injectable Hydrogels for High-Efficient Anti-Infective Wound Therapy

Most injectable hydrogels used in biomedical engineering have unsatisfactory and untunable mechanical properties, making it difficult to match them with the mechanical strengths of different tissues and organs, which can cause a series of adverse consequences such as immune rejection and soft tissue contusion. In this contribution, dopamine-modified hyaluronic acid (HA-DA) is developed as the backbone for an injectable hydrogel using a catechol-Fe³⁺ coordination crosslinking strategy. Due to dynamic physical crosslinking, the hydrogel can be easily injected through a single syringe. Into the hydrogel, black phosphorous nanosheets loaded with a Zr-based porphyrinic metal-organic framework (PCN@BP) are introduced that could generate reactive oxygen species (ROS) under 660 nm laser irradiation, this promotes the oxidative coupling of dopamine in the presence of the ROS, introducing in situ chemical crosslinking into the hydrogel. A physical/chemical double-crosslinked hydrogel is obtained, effectively improving the hydrogel's mechanical properties, which are tuned in situ by adjusting the irradiation time to match the mechanical modulus of different biological tissues. Combining the excellent photothermal properties and photodynamic performance of the PCN@BP nanosheets yields effective sterilization under mild conditions (below 50 °C, low ROS production). The results show that this hydrogel is an excellent multifunctional wound dressing.

Multifunctional Photoactive Hydrogels for Wound Healing Acceleration

Light is an attractive tool that has a profound impact on modern medicine. Particularly, light-based photothermal therapy (PTT) and photodynamic therapy (PDT) show great application prospects in the prevention of wound infection and promoting wound healing. In addition, hydrogels have shown attractive advantages in the field of wound dressings due to their excellent biochemical effects. Therefore, multifunctional photoresponsive hydrogels (MPRHs) that integrate the advantages of light and hydrogels are increasingly used in biomedicine, especially in the field of wound repair. However, a comprehensive review of MPRHs for wound regeneration is still lacking. This review first focuses on various types of MPRHs prepared by diverse photosensitizers, photothermal agents (PHTAs) including transition metal sulfide/oxides nanomaterials, metal nanostructure-based PHTAs, carbon-based PHTAs, conjugated polymer or complex-based PHTAs, and/or photodynamic agents (PHDAs) such as ZnO-based, black-phosphorus-based, TiO₂-based, and small organic molecule-based PHDAs. We also then discuss how PTT, PDT, and photothermal/photodynamic synergistic therapy can modulate the microenvironments of bacteria to inhibit infection. Overall, multifunctional hydrogels with both therapeutic and tissue regeneration capabilities have been discussed and existing challenges, as well as future research directions in the field of MPRHs and their application in wound management are argued.

Mitochondrion-Anchored Photosensitizer with Near Infrared-I Aggregation-Induced Emission for Near Infrared-II Two-Photon Photodynamic Therapy

Two-photon photodynamic therapy (2P-PDT) that employs photosensitizers (PSs) with 2P absorption is particularly intriguing in cancer treatment, in that 2P excitation enables precise spatial localization and deep tissue penetration. Here, a donor-π-acceptor PS (named TPBPy) with near infrared (NIR) aggregation-induced emission (AIE) is designed and synthesized for imaging-guided 2P-PDT. The maximal photoluminescence (PL) peak of TPBPy is as high as 720 nm when it is encapsulated in liposomes. Upon 2P irradiation by a laser in NIR-II window (λ = 1000 nm), TPBPy exhibits strong NIR-I PL in a multicellular tumor spheroids (MCTSs) model, showing an imaging depth of 210 µm that is significantly higher than upon one-photon irradiation. Moreover, TPBPy localizes specifically on mitochondrion, an important organelle in cell oxidative metabolism and apoptosis. When exposed to the NIR-II irradiation, TPBPy can efficiently generate singlet oxygen (¹ O₂ ) and trigger cell death. The efficacy of TPBPy-mediated 2P-PDT has also been validated using 4T1 tumor mouse model, the growth of which is significantly suppressed upon NIR-II laser irradiation. TPBPy herein serves as an excellent candidate to suppress deep tumor tissues through NIR-II 2P-PDT, and also renders a new paradigm to construct mitochondrion-anchored AIE luminogens for future cancer theranostic applications.

Recent Strategies to Develop Innovative Photosensitizers for Enhanced Photodynamic Therapy

This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

Singlet Oxygen "Afterglow" Therapy with NIR-II Fluorescent Molecules

Improving singlet oxygen (1 O2 ) lifespan by fractionated delivery in dark and hypoxic conditions is a better way to achieve enhanced phototherapeutic efficacy. Herein, three boron dipyrromethene (BODIPY) dyes are synthesized to demonstrate that anthracence-functionalized BODIPY, namely ABDPTPA is an efficient heavy-atom-free photosensitizer for the reversible capture and release of 1 O2 . The spin-orbit charge-transfer intersystem crossing of ABDPTPA promises a high 1 O2 quantum yield of 60% in dichloromethane. Under light irradiation, the anthracene group reacts with 1 O2 to produce endoperoxide. Interestingly, after termination of irradiation, the endoperoxide undergoes thermal cycloreversion to produce 1 O2 , and regenerates the anthracene module to achieve 1 O2 "afterglow," which results in a prolonged half lifetime of 1 O2 for 9.2 min. In vitro cytotoxicity assays indicate that ABDPTPA nanoparticles have a low half-maximal inhibitory concentration (IC50 ) of 3.6 µg mL-1 on U87MG cells. Further, the results of near-infrared-II fluorescence-imaging-guided phototherapy indicate that ABDPTPA nanoparticles can inhibit tumor proliferation even at a low dose (200 µg mL-1 , 100 µL) without any side effects. Therefore, the study provides a generalized 1 O2 "afterglow" strategy to enhance phototheranostics for complete tumor regression.

Nano-photosensitizers for enhanced photodynamic therapy

Photodynamic therapy (PDT) utilizes photosensitizers (PSs) together with irradiation light of specific wavelength interacting with oxygen to generate cytotoxic reactive oxygen species (ROS), which could trigger apoptosis and/or necrosis-induced cell death in target tissues. During the past two decades, multifunctional nano-PSs employing nanotechnology and nanomedicine developed, which present not only photosensitizing properties but additionally accurate drug release abilities, efficient response to optical stimuli and hypoxia resistance. Further, nano-PSs have been developed to enhance PDT efficacy by improving the ROS yield. In addition, nano-PSs with additive or synergistic therapies are significant for both currently preclinical study and future clinical practice, given their capability of considerable higher therapeutic efficacy under safer systemic drug dosage. In this review, nano-PSs that allow precise drug delivery for efficient absorption by target cells are introduced. Nano-PSs boosting sensitivity and conversion efficiency to PDT-activating stimuli are highlighted. Nano-PSs developed to address the challenging hypoxia conditions during PDT of deep-sited tumors are summarized. Specifically, PSs capable of synergistic therapy and the emerging novel types with higher ROS yield that further enhance PDT efficacy are presented. Finally, future demands for ideal nano-PSs, emphasizing clinical translation and application are discussed.

Intramolecular Charge Transfer-Based Conjugated Oligomer with Fluorescence, Efficient Photodynamics, and Photothermal Activities

To develop efficient photoactive agents with satisfactory fluorescence, photodynamic, and photothermal effects is crucial for a phototherapeutic strategy to combat cancer diseases and pathogenic microbes. Herein, a water-soluble donor-acceptor-donor (D-A-D) structured conjugated oligomer was designed and synthesized, consisting of two cyclopenta-dithiophene (CDT) units as the electron donor and boron dipyrromethene (BODIPY) as the electron acceptor. Upon excitation, dual emission was observed for CDT-BODIPY with blue and red fluorescence peaks at 463 nm and at 730 nm, respectively, which was ascribed to intramolecular charge transfer (ICT). Due to the ICT effect, the singlet-to-triplet intersystem crossing rate of CDT-BODIPY was also enhanced, leading to an outstanding photodynamic behavior to produce reactive oxygen species (ROS). Meanwhile, its low bandgap also enabled it a moderate photothermal capability with a conversion efficiency of 33.1%. Taking advantage of its phototriggered activities, this conjugated oligomer exhibited an effective inhibition behavior on the pathogenic growth of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans), which can be guided by dual-wavelength fluorescence imaging. This D-A-D type conjugated oligomer with balanced photophysical characteristics provides a promising strategy to imaging-guided photoactive therapy.

Versatile gadolinium(III)-phthalocyaninate photoagent for MR/PA imaging-guided parallel photocavitation and photodynamic oxidation at single-laser irradiation

Current light-mediated photodynamic therapy (PDT) is far underutilized in clinical cancer treatment due to its low pharmacological effect. We herein proposed a new gadolinium(III)-phthalocyanine (GdPc)-enabled phototherapeutics, photoacoustic/dynamic therapy (PADT), towards in vivo solid tumors via parallel-produced photocavitation and photodynamic oxidation with excitation by a single pulsed laser. We demonstrated that pulsed irradiation of GdPc could simultaneously produce an intense acoustic effect and a high-level ¹O₂ quantum yield to afford mitochondrial damage and initiate programmed cell death. Under the guidance of magnetic resonance/photoacoustic dual-modal imaging, the mechanical oxygen-independent destruction of acoustic cavitation and the chemical damage of ¹O₂ were validated to afford combinatorial inhibition of tumors under either normal or hypoxic conditions after the agent delivered into the cancer cells by a pH-sensitive nanomicelle. The single-laser initiated PADT using GdPc as a versatile photoagent maximizes the use of light energy to minimize the dose requirement of oxygen and agent towards high therapeutic efficacy, surpassing dramatically over conventional PDT.

Regioisomer-manipulating thio-perylenediimide nanoagents for photothermal/photodynamic theranostics

Thionated perylenediimides (PDIs) can potentially generate thermal and reactive oxygen species and thus can be used as theranostic agents for photothermal/photodynamic therapy. Herein, thionated cis-/trans-isomer PDI-CS and PDI-TS were designed and prepared to investigate thionation engineering on therapeutic performance. The results revealed that the photodynamic performance is less associated with the positon of sulfur atoms. By contrast, trans-isomer PDI-TS showed a photothermal conversion efficiency of up to 58.4%, which was 40% higher than that of PDI-CS (∼41.6%). An in vitro half-maximal inhibitory concentration of ∼7.78 μg mL-1 was achieved for PDI-TS, which was 1.7-fold smaller than that of PDI-CS, strongly reasserting the regioisomer-modulated phototheranostic performance. Notably, the strong π-π and CS interactions in PDI-TS nanoagents are essential factors attributed to their excellent photothermal performance, indicating that the optimization of non-bonding interactions is an ingenious way to improve phototheranostic performance. This work provides a facile means of creating thio-perylenediimides that possess excellent antitumor properties and a novel proof of concept to improve therapeutic performance through the optimization of non-bonding interactions.

Monodisperse functionalized GO for high-performance sensing and bioimaging of Cu2+ through synergistic enhancement effect

The metal ion fluorescence probes based on chemical reactions triggered by specific metal ions is characterized by high selectivity. However, they are also subject to inherent limitations, such as easy aggregation under water solution, poor optical stability, and long response time. In order to solve these problems, a simple and effective method was studied. The specific design is as follows. Fluorescence probe RACD is assembled onto a single layer graphene oxide (GO) via π-π interaction and hydrogen bonding to prepare RACD functionlized graphene oxide RACD/GO. The experimental results show that the resulting RACD/GO possesses very well monodispersion, hydrophilicity and photostability, particularly reduce the aggregation degree of RACD owing to π-π effect. Simultaneously, it was found that due to the strong synergy between GO and RACD, the response time, selectivity, anti-interference ability, detection sensitivity, detection limit and bioimaging ability of RACD/GO were significantly improved compared with RACD. The resulting RACD/GO not only possesses very well photostability, multiple repeated cycles, but also have been triumphantly put into the monitoring Cu²⁺ of environmental water, sewage, cells and zebrafish specimens in practice. The detection limit is as low as 1.76 nM, and the correlation coefficient is 0.9998.

Broadband Visible Light-Absorbing [70]Fullerene-BODIPY-Triphenylamine Triad: Synthesis and Application as Heavy Atom-Free Organic Triplet Photosensitizer for Photooxidation

A broadband visible light-absorbing [70]fullerene-BODIPY-triphenylamine triad (C70-B-T) has been synthesized and applied as a heavy atom-free organic triplet photosensitizer for photooxidation. By attaching two triphenylmethyl amine units (TPAs) to the π-core of BODIPY via ethynyl linkers, the absorption range of the antenna is extended to 700 nm with a peak at 600 nm. Thus, the absorption spectrum of C70-B-T almost covers the entire UV-visible region (270-700 nm). The photophysical processes are investigated by means of steady-state and transient spectroscopies. Upon photoexcitation at 339 nm, an efficient energy transfer (ET) from TPA to BODIPY occurs both in C70-B-T and B-T, resulting in the appearance of the BODIPY emission at 664 nm. Direct or indirect (via ET) excitation of the BODIPY-part of C70-B-T is followed by photoinduced ET from the antenna to C70, thus the singlet excited state of C70 (1C70*) is populated. Subsequently, the triplet excited state of C70 (3C70*) is produced via the intrinsic intersystem crossing of C70. The photooxidation ability of C70-B-T was studied using 1,5-dihydroxy naphthalene (DHN) as a chemical sensor. The photooxidation efficiency of C70-B-T is higher than that of the individual components of C70-1 and B-T, and even higher than that of methylene blue (MB). The photooxidation rate constant of C70-B-T is 1.47 and 1.51 times as that of C70-1 and MB, respectively. The results indicate that the C70-antenna systems can be used as another structure motif for a heavy atom-free organic triplet photosensitizer.

Single-Molecule Förster Resonance Energy Transfer-Based Photosensitizer for Synergistic Photodynamic/Photothermal Therapy

Photosensitizers (PSs) inevitably release a large amount of energy in the form of fluorescence during photodynamic therapy (PDT). However, under the premise of satisfying fluorescence imaging, a large amount of energy is lost, which limits the efficiency of tumor therapy. Accordingly, in this study, we developed a new strategy (BDP-CR) using the single-molecule Förster resonance energy transfer (smFRET) mechanism to transfer part of the fluorescent energy into heat for combined PDT and photothermal therapy (PTT) featuring the "1 + 1 > 2" amplification effect. Under the 671 nm light irradiation, BDP-CR can produce singlet oxygen (¹O₂) for PDT based on the BDP moiety and also generate hyperthermia to achieve the PTT effect by exciting CR based on the smFRET effect, which effectively kills cancer cells both in vitro and in vivo. This strategy exhibits a broad absorption peak with strong light-harvesting ability, which improves photon utilization for treatment while realizing fluorescence imaging. Of note, owing to the smFRET effect, we achieve a combination treatment outcome at relatively low concentrations and light doses. Thus, we believe that this design concept will provide a new strategy for single-molecule FRET photosensitizers in combination therapy of cancer with potential clinical application prospects.

Platinum-AIEgen coordination complex for imaging-guided annihilation of cisplatin-resistant cancer cells

We report the synthesis and comprehensive characterization of a new platinum-AIEgen coordination complex. Possessing a high 1O2 quantum yield of 0.75 in water, the complex efficiently kills cisplatin-resistant cancer cells under mild white light irradiation. Its strong fluorescence upon binding with proteins also enables direct visualization of its intracellular distribution.

Biocompatible AIEgen/p-glycoprotein siRNA@reduction-sensitive paclitaxel polymeric prodrug nanoparticles for overcoming chemotherapy resistance in ovarian cancer

Nanoparticle drug delivery system (NDDS) is quite different from the widely studied traditional chemotherapy which suffers from drug resistance and side effect. NDDS offers the straightforward solution to the chemotherapy problem and provides an opportunity to monitor the drug delivery process in real time. In this vein, we developed one NDDS, namely Py-TPE/siRNA@PMP, to relieve resistance and side effects during chemotherapy against ovarian cancer. The Py-TPE/siRNA@PMP is a multifunctional polymeric nanoparticle contained several parts as follows: (1) a nanoparticle (NP) self-assembled by reduction-sensitive paclitaxel polymeric prodrug (PMP); (2) the glutathione (GSH)-responsive release of paclitaxel (PTX) for the suppression of ovarian cancer cells; (3) the P-glycoprotein (P-gp) siRNA for restoring the sensitivity of chemo-resistant tumor cells to chemotherapy; (4) the positively charged aggregation-induced emission fluorogen (AIEgen) Py-TPE for tumor imaging and promoting encapsulation of siRNA into the nanoparticle. Methods: The Py-TPE/siRNA@PMP nanoparticles were prepared by self-assembly method and characterized by the UV-Vis absorption spectra, zeta potentials, TEM image, stability assay and hydrodynamic size distributions. The combinational therapeutic effects of Py-TPE/siRNA@PMP on overcoming chemotherapy resistance were explored both in vitro and in vivo.Result: The Py-TPE/siRNA@PMP exhibited an average hydrodynamic size with a good stability. Meanwhile they gave rise to the remarkable chemotoxicity performances in vitro and suppressed the tumors growth in both SKOV-3/PTX (PTX resistance) subcutaneous and intraperitoneal metastasis tumor models. The investigations on ovarian cancer patient-derived xenografts (PDX) model revealed that Py-TPE/siRNA@PMP was able to effectively overcome their chemo-resistance with minimal side effects. Conclusion: Our findings demonstrated the Py-TPE/siRNA@PMP as a promising agent for the highly efficient treatment of PTX-resistant cells and overcoming the shortage of chemotherapy in ovarian cancer.

Synergistic non-bonding interactions based on diketopyrrolo-pyrrole for elevated photoacoustic imaging-guided photothermal therapy

Synergistic non-bonding interactions in fluorine and chalcogen-substituted diketopyrrolopyrrole nanoagents for elevated photoacoustic imaging-guided photothermal therapy.

Terselenophene Regioisomer Conjugated Polymer Materials for High-Performance Cancer Phototheranostics

Molecular isomerization is a fundamental issue in the development of functional materials, with a crucial impact on photophysical properties. However, up to now, their effect on photothermal conversion is rarely investigated. Here, two near-infrared (NIR)-absorbing regioisomer conjugated polymers integrated with cis/trans-terselenophenes are designed and synthesized as efficient photothermal agents to enhance cancer phototheranostics. It is demonstrated that enhanced quinoidal resonance of trans-terselenophenes allows the resulting trans-CP to possess more planar backbone to further increase the effective conjugation length and result in the strong absorption spectra at 808 nm. Characterization of photophysical properties has proved that the photothermal conversion efficiency of trans-CP nanoparticles is up to 61.4%, and they are 210% as strong as cis-CP nanoparticles (29.4%). Further in vitro and in vivo works demonstrate efficient photothermal therapeutic effects with the guidance of photoacoustic imaging. This work affords a new understanding of the molecular isomerization into the development of conjugated materials for high-performance cancer phototheranostics.

A carbazole functionalized semiconducting compound as a heavy atom free photosensitizer for phototherapy against lung cancer

Semiconducting compounds with high photostability and excellent photothermal ability are potential candidates for phototheranostics. In this paper, the heavy atom free compound 3,6-bis(5-(4-(9H-carbazol-9-yl)phenyl)furan-2-yl)-2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (denoted as DPPCz) has been designed and synthesized through a C-H activation coupling reaction. DPPCz has a high singlet oxygen quantum yield (¹O₂ QY) of 40.3% in DCM. In addition, DPPCz NPs obtained by nanoprecipitation exhibit a high photothermal conversion efficiency (48.2%) in water. DPPCz NPs have a low half inhibitory concentration (IC₅₀) of 7.1 μg mL^-1 towards human lung cancer cells (A549) with irradiation while the dark toxicity is almost negligible even at high concentrations. Furthermore, in vivo photothermal imaging guided study demonstrates that these NPs are able to inhibit tumor growth with the help of laser. The H&E stained pictures of the normal tissues indicate the biosafety of DPPCz NPs in that no obvious damage was observed. Our results demonstrate that DPPCz NPs are potential semiconducting photosensitizers for phototheranostics.

An NIR-II-Emissive Photosensitizer for Hypoxia-Tolerant Photodynamic Theranostics

As a common feature in a majority of malignant tumors, hypoxia has become the Achilles' heel of photodynamic therapy (PDT). The development of type-I photosensitizers that show hypoxia-tolerant PDT efficiency provides a straightforward way to address this issue. However, type-I PDT materials have rarely been discovered. Herein, a π-conjugated molecule with A-D-A configuration, COi6-4Cl, is reported. The H₂ O-dispersible nanoparticle of COi6-4Cl can be activated by an 880 nm laser, and displays hypoxia-tolerant type I/II combined PDT capability, and more notably, a high NIR-II fluorescence with a quantum yield over 5%. Moreover, COi6-4Cl shows a negligible photothermal conversion effect. The non-radiative decay of COi6-4Cl is suppressed in the dispersed and aggregated state due to the restricted molecular vibrations and distinct intermolecular steric hindrance induced by its four bulky side chains. These features make COi6-4Cl a distinguished single-NIR-wavelength-activated phototheranostic material, which performs well in NIR-II fluorescence-guided PDT treatment and shows an enhanced in vivo anti-tumor efficiency over the clinically approved Chlorin e6, by the equal stresses on hypoxia-tolerant anti-tumor therapy and deep-penetration imaging. Therefore, the great potential of COi6-4Cl in precise PDT cancer therapy against hypoxia challenges is demonstrated.

Regulation of redox balance using a biocompatible nanoplatform enhances phototherapy efficacy and suppresses tumor metastasis

Many cancer treatments including photodynamic therapy (PDT) utilize reactive oxygen species (ROS) to kill tumor cells. However, elevated antioxidant defense systems in cancer cells result in resistance to the therapy involving ROS. Here we describe a highly effective phototherapy through regulation of redox homeostasis with a biocompatible and versatile nanotherapeutic to inhibit tumor growth and metastasis. We systematically explore and exploit methylene blue adsorbed polydopamine nanoparticles as a targeted and precise nanocarrier, oxidative stress amplifier, photodynamic/photothermal agent, and multimodal probe for fluorescence, photothermal and photoacoustic imaging to enhance anti-tumor efficacy. Remarkably, following the glutathione-stimulated photosensitizer release to generate exogenous ROS, polydopamine eliminates the endogenous ROS scavenging system through depleting the primary antioxidant, thus amplifying the phototherapy and effectively suppressing tumor growth in vitro and in vivo. Furthermore, this approach enables a robust inhibition against breast cancer metastasis, as oxidative stress is a vital impediment to distant metastasis in tumor cells. Innovative, safe and effective nanotherapeutics via regulation of redox balance may provide a clinically relevant approach for cancer treatment.

Conjugated Photosensitizers for Imaging and PDT in Cancer Research

Early cancer detection and perfect understanding of the disease are imperative toward efficient treatments. It is straightforward that, for choosing a specific cancer treatment methodology, diagnostic agents undertake a critical role. Imaging is an extremely intriguing tool since it assumes a follow up to treatments to survey the accomplishment of the treatment and to recognize any conceivable repeating injuries. It also permits analysis of the disease, as well as to pursue treatment and monitor the possible changes that happen on the tumor. Likewise, it allows screening the adequacy of treatment and visualizing the state of the tumor. Additionally, when the treatment is finished, observing the patient is imperative to evaluate the treatment methodology and adjust the treatment if necessary. The goal of this review is to present an overview of conjugated photosensitizers for imaging and therapy.