Luminescent, Oxygen-Supplying, Hemoglobin-Linked Conjugated Polymer Nanoparticles for Photodynamic Therapy

Modular Assembly of Photoactive Lipid Nanoparticles on Red Blood Cells toward Enhanced Phototherapy Efficacy

Photodynamic therapy has been developed as a promising treatment for malignant tumors, which inspires research into photosensitizers. However, the therapeutic efficacy of individual photosensitizers is often hampered by the physiological environment. The assembly of biological materials with synthetic molecules offers a strategy to enhance functionality while improving tolerance to varying physiological conditions. Herein, we present a biohybrid system for enhanced phototherapy efficacy through a simple two-step assembly process. Photoactive lipid nanoparticles were assembled based on synthesized conjugated molecules and lipophilic prodrugs, which were then modularly assembled with red blood cells (RBCs). Driven by hydrophobic and electrostatic interactions, hydrophobic conjugated molecules were efficiently incorporated into the RBCs, while lipophilic prodrugs were simultaneously inserted into the cell membranes. The engineered RBCs harnessed the natural oxygen transport capability, enabling the internal conjugated molecules to effectively produce reactive oxygen species (ROSs) even under oxygen-poor conditions. Meanwhile, the use of ROS-cleavable linkers in prodrugs enhanced drug release for chemotherapy, which is a perfect complement to photodynamic therapy. In vitro and in vivo experiments proved the improved phototherapy efficacy of the biohybrid system. Furthermore, the changes in aggregation directed Förster resonance energy transfer between conjugated molecules and fluorescent drugs provided a mechanism to track drug release from engineered RBCs. Therefore, the modular assembly of biohybrid systems can offer multiple functionalities required for phototherapy, on-demand drug release, and imaging.

Near-Infrared Unimolecular Chemiluminescence Probes for Deep-Tissue Imaging

Chemiluminescence (CL) imaging has emerged as a promising optical imaging technique due to minimal background autofluorescence and being excitation-free. However, the emission of most chemiluminescent probes was concentrated in the visible light region, which limited the tissue penetration. Although some NIR chemiluminescence probes have been reported based on the chemiluminescence resonance energy transfer (CRET) strategy, the energy loss was inevitable. Thus, it is crucial to develop near-infrared (NIR) unimolecular probes with direct chemiluminescence. Herein, we propose a strategy of increasing conjugation for designing and synthesizing novel NIR chemiluminescence unimolecular probes that consist of luminol, electron acceptor, π-bridge, and electron donor. Luminol was conjugated to the unimolecular backbone to produce direct NIR chemiluminescence. Notably, the direct CL mechanism of probes was investigated. Compared with CRET-based chemiluminescence, this direct CL was more advantageous to immediately convert the chemical energy into chemiluminescence, avoiding energy degradation. Furthermore, the corresponding nanoparticles with great biosafety were prepared by self-assembly with amphiphilic DSPE-PEG. Especially, TTBL@PEG-NPs with NIR-I emission were successfully used in the sensitive in vivo chemiluminescence imaging of various inflammation models, such as peritonitis, ear swelling, and colitis. This study paves the way for the design of NIR unimolecular chemiluminescence probes and deep-tissue imaging.

A Self-Cascade Oxygen-Generating Nanomedicine for Multimodal Tumor Therapy

Natural and artificial enzyme oxygen-generating systems for photodynamic therapy (PDT) are developed for tumor treatment, yet they have fallen short of the desired efficacy. Moreover, both the enzymes and photosensitizers usually need carriers for efficient delivery to tumor sites. Here, a self-cascade-enhanced multimodal tumor therapy is developed by ingeniously integrating self-cascade-enhanced PDT with Zn2+-overloading therapy. Manganese-porphyrin (TCPP-Mn) is chosen both as the photosensitizer and catalase (CAT) mimic, which can be encapsulated within glucose oxidase (GOx). Acid-responsive zeolitic imidazolate framework-8 (ZIF-8) is applied as the carrier for TCPP-Mn@GOx (T@G), attaining TCPP-Mn@GOx@ZIF-8 (T@G@Z). T@G@Z demonstrates robust anti-tumor ability as follows: upon the structural degradation of ZIF-8, GOx can mediate the oxidation of glucose and generate hydrogen peroxide (H2O2); TCPP-Mn can catalyze H2O2 into O2 for self-cascade-enhanced PDT; meanwhile, the released Zn2+ can enhance oxidative stress and induce mitochondrial dysfunction by destroying mitochondrial membrane potential; furthermore, immunotherapy can be activated to resist primary tumor and tumor metastasis. The self-cascade-enhanced T@G@Z exhibited its potential application for further tumor management.

Nanomaterial-based regulation of redox metabolism for enhancing cancer therapy

Altered redox metabolism is one of the hallmarks of tumor cells, which not only contributes to tumor proliferation, metastasis, and immune evasion, but also has great relevance to therapeutic resistance. Therefore, regulation of redox metabolism of tumor cells has been proposed as an attractive therapeutic strategy to inhibit tumor growth and reverse therapeutic resistance. In this respect, nanomedicines have exhibited significant therapeutic advantages as intensively reported in recent studies. In this review, we would like to summarize the latest advances in nanomaterial-assisted strategies for redox metabolic regulation therapy, with a focus on the regulation of redox metabolism-related metabolite levels, enzyme activity, and signaling pathways. In the end, future expectations and challenges of such emerging strategies have been discussed, hoping to enlighten and promote their further development for meeting the various demands of advanced cancer therapies. It is highly expected that these therapeutic strategies based on redox metabolism regulation will play a more important role in the field of nanomedicine.

NIR-Activable Charge Transfer Agents for Synergistic Photoimmunotherapy

The combination of photothermal therapy (PTT) and photodynamic therapy (PDT) has become an attractive tumor treatment modality, yet the facile design of photoimmunotheranostic agents with efficient near infrared (NIR) light-absorbing and immune-activating capabilities remains a tremendous challenge. Herein, we developed a NIR-activable organic charge transfer complex (CTC), with perylene (PER) as the electron donor and 4,5,9,10-tetrabromoisochromeno [6,5,4-def]isochromene-1,3,6,8-tetraone (Br4NDI) as the electron acceptor. Through further supramolecular assembly, the PER-Br4NDI nanoparticle (PBND NP) for spatiotemporally controlled photoimmunotherapy was constructed. The PBND NP exhibits superb NIR absorption, robust intermolecular charge transfer, and enhanced intersystem crossing. Upon NIR photoirradiation, the PBND NP effectively exerts photothermal and photodynamic effects with a remarkable photothermal conversion efficiency of 63.5 % and a high reactive oxygen species generation capability, which not only directly ablates primary tumors, but also dramatically suppresses distant tumor growth via promoted immunogenic cell death. Moreover, programmed cell death protein 1 antibody acts synergistically to block immune evasion and ultimately enhances cancer treatment efficacy. This work therefore sheds light on the design of organic CTCs for synergistic photoimmunotherapy.

Self-Chemiluminescence-Triggered Ir(III) Complex Photosensitizer for Photodynamic Therapy against Hypoxic Tumor

The limited optical penetration depth and hypoxic tumor microenvironment (TME) are key factors that hinder the practical applications of conventional photodynamic therapy (PDT). To fundamentally address these issues, self-luminescent photosensitizers (PSs) can achieve efficient PDT. Herein, a self-chemiluminescence (CL)-triggered Ir complex PS, namely, IrL2, with low-O2-dependence type I photochemical processes is reported for efficient PDT. The rational design achieves efficient chemiluminescence resonance energy transfer (CRET) from covalently bonded luminol units to the Ir complex in IrL2 under the catalysis of H2O2 and hemoglobin (Hb) to generate O2•- and 1O2. Liposome IrL2H nanoparticles (NPs) are constructed by loading IrL2 and Hb. The intracellular H2O2 and loaded Hb catalyze the luminol part of IrL2H, and the Ir2 part is then excited to produce types I and II reactive oxygen species (ROS) through CRET, inducing cell death, even under hypoxic conditions, and promoting cell apoptosis. IrL2H is used for tumor imaging and inhibits tumor growth in 4T1-bearing mouse models through intratumoral injection without external light sources. This work provides new designs for transition metal complex PSs that conquer the limitations of external light sources and the hypoxic TME in PDT.

Exclusive generation of a superoxide radical by a porous aromatic framework for fast photocatalytic decontamination of mustard gas simulant in room air

Mustard gas and other chemical warfare agents (CWAs) are a global threat to public security, arising from unpredictable emergencies and chemical spill accidents. So far, photocatalysts such as metal clusters, polyoxometalates and porous solids have been exploited for oxidative degradation of mustard gas, commonly with 1O2 as reactive species. However, the production of 1O2 is oxygen-dependent and requires a high oxygen concentration to sustain the detoxication process. For safety and operation process considerations, it is always preferable to rapidly detoxify dangerous chemicals in the atmosphere of room air. In this work, a porous aromatic framework, PAF-68, was synthesized as a metal-free photocatalyst. In the presence of PAF-68, fast detoxication occurred in typical room air atmosphere. The half-life (t 1/2) for the complete conversion of mustard gas simulant to nontoxic product in room air was only 1.7 min, which is comparable to the performance in pure oxygen, surpassing that of any other porous photocatalysts. It was found that ˙O2 - rather than 1O2 is the predominant reactive species initiated by PAF-68 for mustard gas detoxication. Unlike the formation of 1O2 which prefers the environment of pure oxygen, generation of the ˙O2 - is an oxygen-independent process. It is suggested that amorphous PAFs possess low exciton binding energy and long decay lifetime, which facilitate the generation of ˙O2 -, and this offers a general design strategy to detoxifying chemical warfare agents under real-world conditions.

Catalytic NIR chemiluminescence sensor with enhanced persistence and intensity for in vivo imaging

Chemiluminescence (CL) is a self-illumination phenomenon that involves the emission of light from chemical reactions, and it provides favorable spatial and temporal information on biological processes. However, it is still a great challenge to construct effective CL sensors that equip strong CL intensity, long emission wavelength, and persistent luminescence for deep tissue imaging. Here, we report a liposome encapsulated polymer dots (Pdots)-based system using catalytic CL substrates (L-012) as energy donor and fluorescent polymers and dyes (NIR 695) as energy acceptors for efficient Near-infrared (NIR) CL in vivo imaging. Thanks to the modulation of paired donor and acceptor distance and the slow diffusion of biomarker by liposome, the Pdots show a NIR emission wavelength (λ em, max = 720 nm), long CL duration (>24 h), and a high chemiluminescence resonance energy transfer efficiency (46.5 %). Furthermore, the liposome encapsulated Pdots possess excellent biocompatibility, sensitive response to H2O2, and persistent whole-body NIR CL imaging in the drug-induced inflammation and the peritoneal metastatic tumor mouse model. In a word, this NIR-II CL nanoplatform with long-lasting emission and high spatial-temporal resolution will be a concise strategy in deep tissue imaging and clinical diagnostics.

Macromolecular Nano-Assemblies for Enhancing the Effect of Oxygen-Dependent Photodynamic Therapy Against Hypoxic Tumors

In oxygen (O2)-dependent photodynamic therapy (PDT), photosensitizers absorb light energy, which is then transferred to ambient O2 and subsequently generates cytotoxic singlet oxygen (1O2). Therefore, the availability of O2 and the utilization efficiency of generated 1O2 are two significant factors that influence the effectiveness of PDT. However, tumor microenvironments (TMEs) characterized by hypoxia and limited utilization efficiency of 1O2 resulting from its short half-life and short diffusion distance significantly restrict the applicability of PDT for hypoxic tumors. To address these challenges, numerous macromolecular nano-assemblies (MNAs) have been designed to relieve hypoxia, utilize hypoxia or enhance the utilization efficiency of 1O2. Herein, we provide a comprehensive review on recent advancements achieved with MNAs in enhancing the effectiveness of O2-dependent PDT against hypoxic tumors.

Tumor microenvironment activated mussel-inspired hollow mesoporous nanotheranostic for enhanced synergistic photodynamic/chemodynamic therapy

Anti-tumor therapies reliant on reactive oxygen species (ROS) as primary therapeutic agents face challenges due to a limited oxygen substrate. Photodynamic therapy (PDT) is particularly hindered by inherent hypoxia, while chemodynamic therapy (CDT) encounters obstacles from insufficient endogenous hydrogen peroxide (H2O2) levels. In this study, we engineered biodegradable tumor microenvironment (TME)-activated hollow mesoporous MnO2-based nanotheranostic agents, designated as HAMnO2A. This construct entails loading artemisinin (ART) into the cavity and surface modification with a mussel-inspired polymer ligand, namely hyaluronic acid-linked poly(ethylene glycol)-diethylenetriamine-conjugated (3,4-dihydroxyphenyl) acetic acid, and the photosensitizer Chlorin e6 (mPEG-HA-Dien-(Dhpa/Ce6)), facilitating dual-modal imaging-guided PDT/CDT synergistic therapy. In vitro experimentation revealed that HAMnO2A exhibited ideal physiological stability and enhanced cellular uptake capability via CD44-mediated endocytosis. Additionally, it was demonstrated that accelerated endo-lysosomal escape through the pH-dependent protonation of Dien. Within the acidic and highly glutathione (GSH)-rich TME, the active component of HAMnO2A, MnO2, underwent decomposition, liberating oxygen and releasing both Mn2+ and ART. This process alleviates hypoxia within the tumor region and initiates a Fenton-like reaction through the combination of ART and Mn2+, thereby enhancing the effectiveness of PDT and CDT by generating increased singlet oxygen (1O2) and hydroxyl radicals (•OH). Moreover, the presence of Mn2+ ions enabled the activation of T1-weighted magnetic resonance imaging. In vivo findings further validated that HAMnO2A displayed meaningful tumor-targeting capabilities, prolonged circulation time in the bloodstream, and outstanding efficacy in restraining tumor growth while inducing minimal damage to normal tissues. Hence, this nanoplatform serves as an efficient all-in-one solution by facilitating the integration of multiple functions, ultimately enhancing the effectiveness of tumor theranostics.

Physiological Microenvironment Dependent Self-Cross-Linking of Multifunctional Nanohybrid for Prolonged Antibacterial Therapy via Synergistic Chemodynamic-Photothermal-Biological Processes

Herein, a multifunctional nanohybrid (PL@HPFTM nanoparticles) was fabricated to perform the integration of chemodynamic therapy, photothermal therapy, and biological therapy over the long term at a designed location for continuous antibacterial applications. The PL@HPFTM nanoparticles consisted of a polydopamine/hemoglobin/Fe2+ nanocomplex with comodification of tetrazole/alkene groups on the surface as well as coloading of antimicrobial peptides and luminol in the core. During therapy, the PL@HPFTM nanoparticles would selectively cross-link to surrounding bacteria via tetrazole/alkene cycloaddition under chemiluminescence produced by the reaction between luminol and overexpressed H2O2 at the infected area. The resulting PL@HPFTM network not only significantly damaged bacteria by Fe2+-catalyzed ROS production, effective photothermal conversion, and sustained release of antimicrobial peptides but dramatically enhanced the retention time of these therapeutic agents for prolonged antibacterial therapy. Both in vitro and in vivo results have shown that our PL@HPFTM nanoparticles have much higher bactericidal efficiency and remarkably longer periods of validity than free antibacterial nanoparticles.

Surface Bio-engineered Polymeric Nanoparticles

Surface bio-engineering of polymeric nanoparticles (PNPs) has emerged as a cornerstone in contemporary biomedical research, presenting a transformative avenue that can revolutionize diagnostics, therapies, and drug delivery systems. The approach involves integrating bioactive elements on the surfaces of PNPs, aiming to provide them with functionalities to enable precise, targeted, and favorable interactions with biological components within cellular environments. However, the full potential of surface bio-engineered PNPs in biomedicine is hampered by obstacles, including precise control over surface modifications, stability in biological environments, and lasting targeted interactions with cells or tissues. Concerns like scalability, reproducibility, and long-term safety also impede translation to clinical practice. In this review, these challenges in the context of recent breakthroughs in developing surface-biofunctionalized PNPs for various applications, from biosensing and bioimaging to targeted delivery of therapeutics are discussed. Particular attention is given to bonding mechanisms that underlie the attachment of bioactive moieties to PNP surfaces. The stability and efficacy of surface-bioengineered PNPs are critically reviewed in disease detection, diagnostics, and treatment, both in vitro and in vivo settings. Insights into existing challenges and limitations impeding progress are provided, and a forward-looking discussion on the field's future is presented. The paper concludes with recommendations to accelerate the clinical translation of surface bio-engineered PNPs.

Sensing, Imaging, and Therapeutic Strategies Endowing by Conjugate Polymers for Precision Medicine

Conjugated polymers (CPs) have promising applications in biomedical fields, such as disease monitoring, real-time imaging diagnosis, and disease treatment. As a promising luminescent material with tunable emission, high brightness and excellent stability, CPs are widely used as fluorescent probes in biological detection and imaging. Rational molecular design and structural optimization have broadened absorption/emission range of CPs, which are more conductive for disease diagnosis and precision therapy. This review provides a comprehensive overview of recent advances in the application of CPs, aiming to elucidate their structural and functional relationships. The fluorescence properties of CPs and the mechanism of detection signal amplification are first discussed, followed by an elucidation of their emerging applications in biological detection. Subsequently, CPs-based imaging systems and therapeutic strategies are illustrated systematically. Finally, recent advancements in utilizing CPs as electroactive materials for bioelectronic devices are also investigated. Moreover, the challenges and outlooks of CPs for precision medicine are discussed. Through this systematic review, it is hoped to highlight the frontier progress of CPs and promote new breakthroughs in fundamental research and clinical transformation.

Near-infrared-driven upconversion nanoparticles with photocatalysts through water-splitting towards cancer treatment

Water splitting is promising, especially for energy and environmental applications; however, there are limited studies on the link between water splitting and cancer treatment. Upconversion nanoparticles (UCNPs) can be used to convert near-infrared (NIR) light to ultraviolet (UV) or visible (Vis) light and have great potential for biomedical applications because of their profound penetration ability, theranostic approaches, low self-fluorescence background, reduced damage to biological tissue, and low toxicity. UCNPs with photocatalytic materials can enhance the photocatalytic activities that generate a shorter wavelength to increase the tissue penetration depth in the biological microenvironment under NIR light irradiation. Moreover, UCNPs with a photosensitizer can absorb NIR light and convert it into UV/vis light and emit upconverted photons, which excite the photoinitiator to create H2, O2, and/or OH˙ via water splitting processes when exposed to NIR irradiation. Therefore, combining UCNPs with intensified photocatalytic and photoinitiator materials may be a promising therapeutic approach for cancer treatment. This review provides a novel strategy for explaining the principles and mechanisms of UCNPs and NIR-driven UCNPs with photocatalytic materials through water splitting to achieve therapeutic outcomes for clinical applications. Moreover, the challenges and future perspectives of UCNP-based photocatalytic materials for water splitting for cancer treatment are discussed in this review.

Tunable Fluorescence, Morphology, and Antibacterial Behaviors of Conjugated Oligomers via Host-Guest Supramolecular Self-Assembly

Host-guest supramolecular self-assembly has become one facile but efficient way to regulate the optical properties of conjugated oligomers and construct promising photofunctional materials. Herein, we design two linear conjugated oligomers terminated with two or four pyridinium moieties, which show different 1:1 'head-to-tail' binding patterns with cucurbit[8]uril (CB[8]) to form host-guest supramolecules. After being encapsulated in the hydrophobic cavity of the CB[8] host, the fluorescence emission of the conjugated oligomers undergoes significant changes, resulting in tunable fluorescence color with enhanced quantum yields. Triggered by the aggregation of supramolecules, the regular or rigid binding modes lead to the formation of cuboids and spheroids in nanoscale, respectively. Due to the macrocyclic-confinement effect, the light-driven reactive oxygen species (ROS) production of the host-guest complex is increased significantly, thereby improving the photodynamic antibacterial performance toward Staphylococcus aureus (S. aureus).

Ligand Regulation Strategy to Modulate ROS Nature in a Rhodamine-Iridium(III) Hybrid System for Phototherapy

The efficacy of photodynamic therapy (PDT) is highly dependent on the photosensitizer features. The reactive oxygen species (ROS) generated by photosensitizers is proven to be associated with immunotherapy by triggering immunogenic cell death (ICD) as well. In this work, we establish a rhodamine-iridium(III) hybrid model functioning as a photosensitizer to comprehensively understand its performance and potential applications in photodynamic immunotherapy. Especially, the correlation between the ROS generation efficiency and the energy level of the Ir(III)-based excited state (T1'), modulated by the cyclometalating (C∧N) ligand, is systematically investigated and correlated. We prove that in addition to the direct population of the rhodamine triplet state (T1) formed through the intersystem crossing process with the assistance of a heavy Ir(III) metal center, the fine-tuned T1' state could act as a relay to provide an additional pathway for promoting the cascade energy transfer process that leads to enhanced ROS generation ability. Moreover, type I ROS can be effectively produced by introducing sulfur-containing thiophene units in C∧N ligands, providing a stronger M1 macrophage-activation efficiency under hypoxia to evoke in vivo antitumor immunity. Overall, our work provides a fundamental guideline for the molecular design and exploration of advanced transition-metal-based photosensitizers for biomedical applications.

Hypoxia Reversion by Low-Immunogenic Ultra-Acid-Sensitive Comicelles of Protein-Polymer Conjugates Sensitizes Tumors to Photodynamic Therapy

Hypoxia is characteristic of the tumor microenvironment, which is correlated with resistance to photodynamic therapy (PDT), radiotherapy, chemotherapy, and immunotherapy. Catalase is potentially useful to catalyze the conversion of endogenous H2O2 to O2 for hypoxia reversion. However, the efficient delivery of catalase into the hypoxia regions of tumors is a huge challenge. Here, we report the self-assembly of ultra-acid-sensitive polymer conjugates of catalase and albumin into nanomicelles that are responsive to the acidic tumor microenvironment. The immunogenicity of catalase is mitigated by the presence of albumin, which reduces the cross-linking of catalase with B cell receptors, resulting in improved pharmacokinetics. The ultra acid sensitivity of the nanomicelles makes it possible to efficiently escape the lysosomal degradation after endocytosis and permeate into the interior of tumors to reverse hypoxia in vitro and in vivo. In mice bearing triple-negative breast cancer, the nanomicelles loaded with a photosensitizer effectively accumulate and penetrate into the whole tumors to generate a sufficient amount of O2 to reverse hypoxia, leading to enhanced efficacy of PDT without detectable side effects. These findings provide a general strategy of self-assembly to design low-immunogenic ultra-acid-sensitive comicelles of protein-polymer conjugates to reverse tumor hypoxia, which sensitizes tumors to PDT.

Coupled Poly(ethylenimine) Coreactant to Enhance Electrochemiluminescence of Polymer Dots for Array Imaging of Protein Biomarkers

Traditional electrochemiluminescent (ECL) bioanalysis suffers from the demand for excessive external coreactants and the damage of reaction intermediates. In this work, a poly(ethylenimine) (PEI)-coupled ECL emitter was proposed by covalently coupling tertiary amine-rich PEI to polymer dots (Pdots). The coupled PEI might act as a highly efficient coreactant to enhance the ECL emission of Pdots through intramolecular electron transfer, reducing the electron transfer distance between emitter and coreactant intermediates and avoiding the disadvantages of traditional ECL systems. Through modification of the PEI-Pdots with tDNA, a sequence partially complementary to cDNA that was complementary to the aptamer of target protein biomarker (aDNA), tDNA-PEI-Pdots were obtained. The biosensors were produced using Au/indium tin oxide (ITO) with an aDNA/cDNA hybrid, and an ECL imaging biosensor array was constructed for ultrasensitive detection of protein biomarkers. Using vascular endothelial growth factor 165 (VEGF165) as a protein model, the proposed ECL imaging method containing two simple incubations with target samples and then tDNA-PEI-Pdots showed a detectable range of 1 pg mL-1 to 100 ng mL-1 and a detection limit of 0.71 pg mL-1, as well as excellent performance such as low toxicity, high sensitivity, excellent selectivity, good accuracy, and acceptable fabrication reproducibility. The PEI-coupled Pdots provide a new avenue for the design of ECL emitters and the application of ECL imaging in disease biomarker detection.

Chemiluminescent Conjugated Polymer Nanoparticles for Deep-Tissue Inflammation Imaging and Photodynamic Therapy of Cancer

Deep-tissue optical imaging and photodynamic therapy (PDT) remain a big challenge for the diagnosis and treatment of cancer. Chemiluminescence (CL) has emerged as a promising tool for biological imaging and in vivo therapy. The development of covalent-binding chemiluminescence agents with high stability and high chemiluminescence resonance energy transfer (CRET) efficiency is urgent. Herein, we design and synthesize an unprecedented chemiluminescent conjugated polymer PFV-Luminol, which consists of conjugated polyfluorene vinylene (PFV) main chains and isoluminol-modified side chains. Notably, isoluminol groups with chemiluminescent ability are covalently linked to main chains by amide bonds, which dramatically narrow their distance, greatly improving the CRET efficiency. In the presence of pathologically high levels of various reactive oxygen species (ROS), especially singlet oxygen (1O2), PFV-Luminol emits strong fluorescence and produces more ROS. Furthermore, we construct the PFV-L@PEG-NPs and PFV-L@PEG-FA-NPs nanoparticles by self-assembly of PFV-Luminol and amphiphilic copolymer DSPE-PEG/DSPE-PEG-FA. The chemiluminescent PFV-L@PEG-NPs nanoparticles exhibit excellent capabilities for in vivo imaging in different inflammatory animal models with great tissue penetration and resolution. In addition, PFV-L@PEG-FA-NPs nanoparticles show both sensitive in vivo chemiluminescence imaging and efficient chemiluminescence-mediated PDT for antitumors. This study paves the way for the design of chemiluminescent probes and their applications in the diagnosis and therapy of diseases.

Development of novel polymer haemoglobin based particles as an antioxidant, antibacterial and an oxygen carrier agents

This innovative work aims to develop highly biocompatible and degradable nanoparticles by encapsulating haemoglobin (Hb) within poly-ε-caprolactone for novel biomedical applications. We used a modified double emulsion solvent evaporation method to fabricate the particles. A Scanning electron microscope (SEM) characterized them for surface morphology. Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet-visible spectroscopies (UV-visible) elucidated preserved chemical and biological structure of encapsulated haemoglobin. The airproof equilibrium apparatus obtained the oxygen-carrying capacity and P50 values. The DPPH assay assessed free radical scavenging potential. The antibacterial properties were observed using four different bacterial strains by disk diffusion method. The MTT assay investigates the cytotoxic effects on mouse fibroblast cultured cell lines (L-929). The MTT assay showed that nanoparticles have no toxicity over large concentrations. The well-preserved structure of Hb within particles, no toxicity, high oxygen affinity, P50 value, and IC50 values open the area of new research, which may be used as artificial oxygen carriers, antioxidant, and antibacterial agents, potential therapeutic agents as well as drug carrier particles to treat the cancerous cells. The novelty of this work is the antioxidant and antibacterial properties of developed nanoparticles are not been reported yet. Results showed that the prepared particles have strong antioxidant and antibacterial potential.

Deepened Photodynamic Therapy through Skin Optical Clearing Technology in the Visible Light Window

The trade-off that shorter wavelength light facilitates the efficient generation of reactive oxygen species (ROS) from photosensitizer (PS) while facing the drawback of limited penetration depth through skin tissue restricts the further development of photodynamic therapy (PDT). Here, we address this contradiction and achieve visible-light-tailored deep PDT combined with the skin optical clearing technology. With the help of the prepared skin optical clearing gel, the refractive index inhomogeneity between skin tissue components is greatly attenuated, and the light scattering effect within the skin tissue is remarkably reduced. As a consequence, the transmittance of visible light at 600 nm through in vitro porcine skin and in vivo mouse skin after treatment increases from approximately 10 and 40 to 70 and 70%, respectively. Furthermore, in the tumor cell eradication experiment, the local ROS generation efficiency in the experimental group is several times higher than that in the control group owing to improved visible transmittance, which is thus responsible for the complete eradication of tumor cells, even when shaded by skin tissue. The results suggest that this strategy may serve as a valuable supplement to the current deep PDT strategies.

A laser free self-luminous nanosystem for photodynamic therapy of cervical cancer cells

Photodynamic therapy is a tumor treatment strategy. However, most of the photodynamic therapies rely on laser irradiation triggering, which limits their application in deep tissues. This study designed a self-luminescent nano system, hybrid protein oxygen nanocarrier coated graphene quantum dots (GQDs@HPOC) and mesoporous silica nanoparticles coated Luminol (L@MSNs), which self-assembled into GQDs@HPOC/L@MSNs without laser irradiation. The system utilized the weak acidic environment of tumors to trigger the release of Luminol and the chemiluminescence was catalyzed by HPOC. Next CRET occurred between Luminol and GQDs, producing 1O2, which could generate photodynamic damage to cervical cancer cells without the need for external laser irradiation. The system achieved the peak uptake in primary cervical cancer cells in 3 h, and had good biosafety before self-assembly. The system could significantly kill cells at a concentration of 16 μg/ml. The system will be further applied in in vivo experiments to investigate its therapeutic ability, providing a new strategy for the clinical treatment of cervical cancer.

Composite Nanomaterials of Conjugated Polymers and Upconversion Nanoparticles for NIR-Triggered Photodynamic/Photothermal Synergistic Cancer Therapy

Phototherapies such as photodynamic therapy (PDT) and photothermal therapy (PTT) have attracted great attention in the field of cancer treatment. However, the individual PDT or PTT makes it difficult to achieve optimal antitumor effects compared to the PDT/PTT combined therapy. Also, the effect of PDT is usually limited by the penetration depth of the UV-vis light source. Herein, we designed and synthesized novel composite nanoparticles UCNPs-CPs, which are constructed from two conjugated polymers and upconversion nanoparticles β-NaYF4:Yb,Tm (UCNPs) via a coordination reaction. By virtue of the excellent spectral overlap between absorption of conjugated polymers and emission of UCNPs, the UCNPs can absorb NIR light and effectively excite conjugated polymers by energy transfer to produce massive reactive oxygen species under 980 nm excitation and heat energy under 808 nm laser irradiation, achieving photodynamic/photothermal synergistic therapy. The in vitro cellular investigation proves that the dual modal phototherapy exhibits enhanced antitumor ability compared to single PDT or PTT. Furthermore, UCNPs-CPs inhibit tumor growth 100% in a 4T1 breast tumor mice model with both NIR laser irradiation, indicating that UCNPs-CPs is an excellent platform for synergistic PDT/PTT treatment. Thus, this study provides a promising strategy for NIR-triggered dual modal phototherapy.

Beyond External Light: On-Spot Light Generation or Light Delivery for Highly Penetrated Photodynamic Therapy

External light sources, such as lasers, light emitting diodes (LEDs) and lamps, are widely applied in photodynamic therapy (PDT); however, their use is severely limited by the nature of shallow tissue penetration depth. The recent exploration of light delivery or local generation on tumor sites has attracted much attention, owing to the fact that these systems are significantly endowed with high tissue penetration. In this review, we briefly introduced the principle of "on-spot light generation or delivery systems" in PDT. These systems are divided into different categories: (1) implantable luminescence, (2) mechanoluminescence, (3) electrochemiluminescence, (4) Cerenkov luminescence, (5) chemiluminescence, and (6) bioluminescence. Finally, their applications, advantages, and disadvantages in PDT will be appropriately summarized and further discussed in detail. We believe that this review will provide general guidance for the further design of light generation or delivery systems and clinical studies for PDT-mediated cancer treatments with unparalleled merits.

Photothermal-Triggered Sulfur Oxide Gas Therapy Augments Type I Photodynamic Therapy for Potentiating Cancer Stem Cell Ablation and Inhibiting Radioresistant Tumor Recurrence

Despite advances in cancer therapy, the existence of self-renewing cancer stem cells (CSC) can lead to tumor recurrence and radiation resistance, resulting in treatment failure and high mortality in patients. To address this issue, a near-infrared (NIR) laser-induced synergistic therapeutic platform has been developed by incorporating aggregation-induced emission (AIE)-active phototheranostic agents and sulfur dioxide (SO2 ) prodrug into a biocompatible hydrogel, namely TBH, to suppress malignant CSC growth. Outstanding hydroxyl radical (·OH) generation and photothermal effect of the AIE phototheranostic agent actualizes Type I photodynamic therapy (PDT) and photothermal therapy through 660 nm NIR laser irradiation. Meanwhile, a large amount of SO2 is released from the SO2 prodrug in thermo-sensitive TBH gel, which depletes upregulated glutathione in CSC and consequentially promotes ·OH generation for PDT enhancement. Thus, the resulting TBH hydrogel can diminish CSC under 660 nm laser irradiation and finally restrain tumor recurrence after radiotherapy (RT). In comparison, the tumor in the mice that were only treated with RT relapsed rapidly. These findings reveal a double-boosting ·OH generation protocol, and the synergistic combination of AIE-mediated PDT and gas therapy provides a novel strategy for inhibiting CSC growth and cancer recurrence after RT, which presents great potential for clinical treatment.

MnO2 Decorated Metal-Organic Framework-Based Hydrogel Relieving Tumor Hypoxia for Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) has emerged as a promising cancer treatment modality; however, its therapeutic efficacy is greatly limited by tumor hypoxia. In this study, a metal-organic framework (MOF)-based hydrogel (MOF Gel) system that synergistically combines PDT with the supply of oxygen is designed. Porphyrin-based Zr-MOF nanoparticles are synthesized as the photosensitizer. MnO2 is decorated onto the surface of the MOF, which can effectively convert H₂O₂ into oxygen. Simultaneously, the incorporation of MnO2 -decorated MOF (MnP NPs) into a chitosan hydrogel (MnP Gel) serves to enhance its stability and retention at the tumor site. The results show that this integrated approach significantly improves tumor inhibition efficiency by relieving tumor hypoxia and enhancing PDT. Overall, the findings underscore the potential for employing nano-MOF-based hydrogel systems as promising agents for cancer therapy, thus advancing the application of multifunctional MOFs in cancer treatment.

A "Chase and Block" Strategy for Enhanced Cancer Therapy with Hypoxia-Promoted Photodynamic Therapy and Autophagy Inhibition Based on Upconversion Nanocomposites

The combination of hypoxia-promoted photodynamic therapy (PDT) and autophagy modulation has shown strong potential in the treatment of hypoxic tumors. Here, a novel design is put forward for synergistic PDT and autophagy inhibition to amplify the effect of cancer therapy by a "chase and block" strategy. Specifically, the organic photosensitive molecule (denoted FL) is encapsulated in a hydrophobic layer between multi-band emitted upconversion nanoparticles (UCNPs) and the amphiphilic polymer DSPE-PEG-COOH, allowing FL to fully exploit the luminescence spectrum of UCNPs under near-infrared (NIR) light irradiation. The FL is specifically activated by nitroreductase in the tumor microenvironment (TME), enabling hypoxia-promoted PDT and thus performing a "chase" strategy for cancer therapy. Additionally, the nanosystem is combined with an autophagy-inhibiting melittin pro-peptide (denoted as MEL), which could be triggered by the highly expressed legumain in tumor cells to inhibit the autophagy procedure by disrupting the lysosomal membrane, thus "blocking" the cancer cells from rescuing themselves and amplifying the killing effect of PDT. Both FL and MEL can be specifically activated by TME and the upconversion luminescence imaging of UCNPs offers a tracer function for the treatment. Therefore, UCNPs@FL-MEL might be an important reference for the design and development of future nanotherapeutic agents.

Silica-Based Platform Decorated with Conjugated Polymer Dots and Prussian Blue for Improved Photodynamic Cancer Therapy

To advance cancer treatment, we have developed a novel composite material consisting of conjugated polymer dots (CPDs) and Prussian blue (PB) particles, which were immobilized on, and encapsulated within, silica particles, respectively. The CPDs functioned as both a photosensitizer and a photodynamic agent, and the PB acted as a photothermal agent. The silica platform provided a biocompatible matrix that brought the two components into close proximity. Under laser irradiation, the fluorescence from the CPDs in the composite material enabled cell imaging and was subsequently converted to thermal energy by PB. This efficient energy transfer was accomplished because of the spectral overlap between the emission of donor CPDs and the absorbance of acceptor PB. The increase in local temperature in the cells resulted in a significant increase in the amount of reactive oxygen species (ROS) generated by CPDs, in which their independent use did not produce sufficient ROS for cancer cell treatment. To assess the impact of the enhanced ROS generation by the composite material, we conducted experiments using cancer cells under 532 nm laser irradiation. The results showed that with the increase in local temperature, the generated ROS increased by 30% compared with the control, which did not contain PB. When the silica-based composite material was positioned at the periphery of the tumor for 120 h, it led to a much slower tumor growth than other materials tested. By using a CPD-based photodynamic therapy platform, a new simplified approach to designing and preparing cancer treatments could be achieved, which included photothermal PB-assisted enhanced ROS generation using a single laser. This advancement opens up an exciting new opportunity for effective cancer treatment.

Nucleus-selective self-augmenting cascade nanoassemblies for targeted synergistic photo-chemo therapy of tumors

A nucleus-targeted enzyme prodrug nanocomposite, assembled from β-cyclodextrin-lysine (CL), catalase (CAT), Pt(IV) and chlorin e6 (Ce6), was developed for self-augmenting cascade photo-chemo therapy of tumors. It can effectively transport through the cytoplasm and accumulate in the nucleus, thereby significantly inhibiting tumor growth and lung metastasis.

Emission Wavelength-Tunable Bicyclic Dioxetane Chemiluminescent Probes for Precise In Vitro and In Vivo Imaging

Chemiluminescent probes have become increasingly popular in various research areas including precise tumor imaging and immunofluorescence analysis. Nevertheless, previously developed chemiluminescence probes are mainly limited to studying oxidation reaction-associated biological events. This study presents the first example of bioimaging applicable bicyclic dioxetane chemiluminescent probes with tunable emission wavelengths that range from 525 to 800 nm. These newly developed probes were able to detect the analytes of β-Gal, H2O2, and superoxide with high specificity and a limit of detection of 77 mU L-1, 96, and 28 nM, respectively. The bioimaging application of the probes was verified in ovarian and liver cancer cells and macrophage cells, allowing the detection of the content of β-Gal, H2O2, and superoxide inside the cells. The high specificity allowed us to image the xenografted tumor in mice. We expect that our probes will receive extensive applications in recording complex biomolecular events using noninvasive imaging techniques.

Escherichia coli-Based In Situ Triggerable Probe as an Amplifier for Sensitive Diagnosis and Penetrated Therapy of Cancer

Escherichia coli (E. coli) was used for cancer therapy due to the tumor-targeting, catalytic, and surface-reducing properties. Effective diagnosis combined with treatment of cancer based on E. coli, however, was rarely demonstrated. In this study, E. coli was used to surface reduce HAuCl4 and as a carrier to modify riboflavin (Rf) and luminol (E-Au@Rf@Lum). After targeted delivery to tumor, the E-Au@Rf@Lum probe could actively emit 425 nm blue-violet chemiluminescence (CL) to achieve cell imaging for cancer diagnosis. Furthermore, this light could in situ trigger the photosensitizer (Rf) through CL resonance energy transfer, which produces reactive oxygen species (ROS) for accurate photodynamic therapy. In return, the excessive ROS enhanced the blue-violet light which was further absorbed by Rf, and ROS production was cyclically amplified. Abundant ROS broke down the dense extracellular matrix network and penetrated deep into tumors. Besides, E. coli with excellent catalytic property could decompose H2O2 to O2 to relieve tumor hypoxia for a long time and enhance the photosensitized process of Rf. By self-illumination, effective penetration, and tumor hypoxia relief, this work opens a self-amplified therapy modality to tumor.

Strategic Design of Conquering Hypoxia in Tumor for Advanced Photodynamic Therapy

Photodynamic therapy (PDT), with its advantages of high targeting, minimally invasive, and low toxicity side effects, has been widely used in the clinical therapy of various tumors, especially superficial tumors. However, the tumor microenvironment (TME) presents hypoxia due to the low oxygen (O2 ) supply caused by abnormal vascularization in neoplastic tissues and high O2 consumption induced by the rapid proliferation of tumor cells. The efficacy of oxygen-consumping PDT can be hampered by a hypoxic TME. To address this problem, researchers have been developing advanced nanoplatforms and strategies to enhance the therapeutic effect of PDT in tumor treatment. This review summarizes recent advanced PDT therapeutic strategies to against the hypoxic TME, thus enhancing PDT efficacy, including increasing O2 content in TME through delivering O2 to the tumors and in situ generations of O2 ; decreasing the O2 consumption during PDT by design of type I photosensitizers. Moreover, recent synergistically combined therapy of PDT and other therapeutic methods such as chemotherapy, photothermal therapy, immunotherapy, and gas therapy is accounted for by addressing the challenging problems of mono PDT in hypoxic environments, including tumor resistance, proliferation, and metastasis. Finally, perspectives of the opportunities and challenges of PDT in future clinical research and translations are provided.

Host-Guest Interaction-Based Supramolecular Self-Assemblies for H2O2 Upregulation Augmented Chemiluminescence Resonance Energy Transfer-Induced Cancer Therapy

Given that light is hard to reach deep tumor tissue, how to enhance photodynamic therapy (PDT) efficacy is a big challenge. Herein, we proposed the supramolecular polymer self-assemblies (HACP) with bis[2,4,5-trichloro-6 (pentyloxycar-bonyl) phenyl] oxalate as the cargos (HACP@CPPO) to realize the chemiluminescence resonance energy transfer (CRET)-induced generation of 1O2 in situ. HACP was prepared by cinnamaldehyde-modified hyaluronic acid (HA-CA) and β-cyclodextrin-modified protoporphyrin IX (β-CD-PPIX) via host-guest interactions. The CA moiety could elevate H2O2 levels for the enhanced production of chemical energy and macrocyclic CD could enhance the stacking distance of PPIX for enhanced 1O2 yield. Thus, HACP@CPPO exhibited excellent antitumor performance without light irradiation.

Gas-assisted phototherapy for cancer treatment

Phototherapies, mainly including photodynamic and photothermal therapy, have made considerable strides in the field of cancer treatment. With the aid of phototherapeutic agents, reactive oxygen species (ROS) or heat are generated under light irradiation to selectively damage cancer cells. However, sole-modality phototherapy faces certain drawbacks, such as limited penetration of phototherapeutic agents into tumor tissues, inefficient ROS generation due to hypoxia, treatment-induced inflammation and resistance of tumor to treatment (e.g., high levels of antioxidants, expression of heat shock protein). Gas therapy, an emerging therapy approach that damages cancer cells by improving the level of certain gas at the tumor site, shows potential to overcome the challenges associated with phototherapies. In addition, with the rapid development of nanotechnology, gas-assisted phototherapy based on nanomedicines has emerged as a promising strategy to enhance the treatment efficacy. This review summarizes recent advances in gas-assisted phototherapy and discusses the prospects and challenges of this strategy in cancer phototherapy.

Ultrasound-Triggered Cascade Amplification of Nanotherapy

Ultrasound (US)-triggered cascade amplification of nanotherapies has attracted considerable attention as an effective strategy for cancer treatment. With the remarkable advances in materials chemistry and nanotechnology, a large number of well-designed nanosystems have emerged that incorporate presupposed cascade amplification processes and can be activated to trigger therapies such as chemotherapy, immunotherapy, and ferroptosis, under exogenous US stimulation or specific substances generated by US actuation, to maximize antitumor efficacy and minimize detrimental effects. Therefore, summarizing the corresponding nanotherapies and applications based on US-triggered cascade amplification is essential. This review comprehensively summarizes and highlights the recent advances in the design of intelligent modalities, consisting of unique components, distinctive properties, and specific cascade processes. These ingenious strategies confer unparalleled potential to nanotherapies based on ultrasound-triggered cascade amplification and provide superior controllability, thus overcoming the unmet requirements of precision medicine and personalized treatment. Finally, the challenges and prospects of this emerging strategy are discussed and it is expected to encourage more innovative ideas and promote their further development.

Conjugated Polymeric Materials in Biological Imaging and Cancer Therapy

Conjugated polymers (CPs) have attracted much attention in the fields of chemistry, medicine, life science, and material science. Researchers have carried out a series of innovative researches and have made significant research progress regarding the unique photochemical and photophysical properties of CPs, expanding the application range of polymers. CPs are polymers formed by the conjugation of multiple repeating light-emitting units. Through precise control of their structure, functional molecules with different properties can be obtained. Fluorescence probes with different absorption and emission wavelengths can be obtained by changing the main chain structure. By modifying the side chain structure with water-soluble groups or selective recognition molecules, electrostatic interaction or specific binding with specific targets can be achieved; subsequently, the purpose of selective recognition can be achieved. This article reviews the research work of CPs in cell imaging, tumor diagnosis, and treatment in recent years, summarizes the latest progress in the application of CPs in imaging, tumor diagnosis, and treatment, and discusses the future development direction of CPs in cell imaging, tumor diagnosis, and treatment.

ROS/Electro Dual-Reactive Nanogel for Targeting Epileptic Foci to Remodel Aberrant Circuits and Inflammatory Microenvironment

Medicinal treatment against epilepsy is faced with intractable problems, especially epileptogenesis that cannot be blocked by clinical antiepileptic drugs (AEDs) during the latency of epilepsy. Abnormal circuits of neurons interact with the inflammatory microenvironment of glial cells in epileptic foci, resulting in recurrent seizures and refractory epilepsy. Herein, we have selected phenytoin (PHT) as a model drug to derive a ROS-responsive and consuming prodrug, which is combined with an electro-responsive group (sulfonate sodium, SS) and an epileptic focus-recognizing group (α-methyl-l-tryptophan, AMT) to form hydrogel nanoparticles (i.e., a nanogel). The nanogel will target epileptic foci, release PHT in response to a high concentration of reactive oxygen species (ROS) in the microenvironment, and inhibit overexcited circuits. Meanwhile, with the clearance of ROS, the nanogel can also reduce oxidative stress and alleviate microenvironment inflammation. Thus, a synergistic regulation of epileptic lesions will be achieved. Our nanogel is expected to provide a more comprehensive strategy for antiepileptic treatment.

Conjugated Polymer Nanoparticles for Tumor Theranostics

Water-dispersible conjugated polymer nanoparticles (CPNs) have demonstrated great capabilities in biological applications, such as in vitro cell/subcellular imaging and biosensing, or in vivo tissue imaging and disease treatment. In this review, we summarized the recent advances of CPNs used for tumor imaging and treatment during the past five years. CPNs with different structures, which have been applied to in vivo solid tumor imaging (fluorescence, photoacoustic, and dual-modal) and treatment (phototherapy, drug carriers, and synergistic therapy), are discussed in detail. We also demonstrated the potential of CPNs as cancer theranostic nanoplatforms. Finally, we discussed current challenges and outlooks in this field.

A Smart Benzothiazole-Based Conjugated Polymer Nanoplatform with Multistimuli Response for Enhanced Synergistic Chemo-Photothermal Cancer Therapy

The combination of chemotherapy and phototherapy has received tremendous attention in multimodal cancer therapy. However, satisfactory therapeutic outcomes of chemo-photothermal therapy (chemo-PTT) still remain challenging. Herein, a biocompatible smart nanoplatform based on benzothiazole-linked conjugated polymer nanoparticles (CPNs) is rationally designed, for effectively loading doxorubicin (DOX) and Mo-based polyoxometalate (POM) through both dynamic chemical bond and intermolecular interactions, with an expectation to obtain new anticancer drugs with multiple stimulated responses to the tumor microenvironment (TME) and external laser irradiation. Controlled drug release of DOX from the obtained nanoformulation (CPNs-DOX-PEG-cRGD-BSA@POM) triggered by both endogenous stimulations (GSH and low pH) and exogenous laser irradiation has been well demonstrated by pharmacodynamics investigations. More intriguingly, incorporating POM into the nanoplatform not only enables the nanomedicine to achieve mild hyperthermia but also makes it exhibit self-assembly behavior in acidic TME, producing enhanced tumor retention. Benefiting from the versatile functions, the prepared CPNs-DOX-PEG-cRGD-BSA@POM exhibited excellent tumor targeting and therapeutic effects in murine xenografted models, showing great potential in practical cancer therapy.

Pt nanozyme-bridged covalent organic framework-aptamer nanoplatform for tumor targeted self-strengthening photocatalytic therapy

Covalent organic frameworks (COFs) have emerged as a promising platform for nanomedicine, while developing multifunctional COF nanoplatforms remains challenging due to the lack of efficient strategies for COF modification. Herein, we propose a nanozyme bridging (NZB) strategy for COF functionalization. Platinum nanoparticles (Pt NPs) as catalase mimics were in situ grown on the surface of COF NPs without reducing their drug loading capacity (CP), and thiol-terminated aptamer was further densely decorated onto CP NPs via a stable Pt-S bond (CPA). Pt nanozyme engineering and aptamer functionalization rendered the nanoplatform with excellent photothermal conversion, tumor targeting, and catalase-like catalytic performances. Using clinical-approved photosensitizer indocyanine green (ICG) as a model drug, we fabricated a nanosystem (ICPA) for tumor-targeted self-strengthening therapy. ICPA can effectively accumulate into tumor tissue and relieve the hypoxia microenvironment by decomposing the overexpressed H₂O₂ and generating O₂. Under monowavelength NIR light irradiation, the catalase-like catalytic and singlet oxygen generation activities of ICPA can be significantly strengthened, leading to admirable photocatalytic treatment effects against malignant cells as well as tumor-bearing mice in a self-strengthening manner.

Photodynamic therapy: Innovative approaches for antibacterial and anticancer treatments

Photodynamic therapy is an alternative treatment mainly for cancer but also for bacterial infections. This treatment dates back to 1900 when a German medical school graduate Oscar Raab found a photodynamic effect while doing research for his doctoral dissertation with Professor Hermann von Tappeiner. Unexpectedly, Raab revealed that the toxicity of acridine on paramecium depends on the intensity of light in his laboratory. Photodynamic therapy is therefore based on the administration of a photosensitizer with subsequent light irradiation within the absorption maxima of this substance followed by reactive oxygen species formation and finally cell death. Although this treatment is not a novelty, there is an endeavor for various modifications to the therapy. For example, selectivity and efficiency of the photosensitizer, as well as irradiation with various types of light sources are still being modified to improve final results of the photodynamic therapy. The main aim of this review is to summarize anticancer and antibacterial modifications, namely various compounds, approaches, and techniques, to enhance the effectiveness of photodynamic therapy.

Multifunctional Protein Hybrid Nanoplatform for Synergetic Photodynamic-Chemotherapy of Malignant Carcinoma by Homologous Targeting Combined with Oxygen Transport

Photodynamic therapy (PDT) under hypoxic conditions and drug resistance in chemotherapy are perplexing problems in anti-tumor treatment. In addition, central nervous system neoplasm-targeted nanoplatforms are urgently required. To address these issues, a new multi-functional protein hybrid nanoplatform is designed, consisting of transferrin (TFR) as the multicategory solid tumor recognizer and hemoglobin for oxygen supply (ODP-TH). This protein hybrid framework encapsulates the photosensitizer protoporphyrin IX (PpIX) and chemotherapeutic agent doxorubicin (Dox), which are attached by a glutathione-responsive disulfide bond. Mechanistically, ODP-TH crosses the blood-brain barrier (BBB) and specifically aggregated in hypoxic tumors via protein homology recognition. Oxygen and encapsulated drugs ultimately promote a therapeutic effect by down-regulating the abundance of multidrug resistance gene 1 (MDR1) and hypoxia-inducible factor-1-α (HIF-1α). The results reveal that ODP-TH achieves oxygen transport and protein homology recognition in the hypoxic tumor occupation. Indeed, compared with traditional photodynamic chemotherapy, ODP-TH achieves a more efficient tumor-inhibiting effect. This study not only overcomes the hypoxia-related inhibition in combination therapy by targeted oxygen transport but also achieves an effective treatment of multiple tumors, such as breast cancer and glioma, providing a new concept for the construction of a promising multi-functional targeted and intensive anti-tumor nanoplatform.

A hypoxia responsive silicon phthalocyanine containing naphthquinone axial ligands for photodynamic therapy activity

A liposome loaded‑silicon (IV) phthalocyanine (SiPc) containing naphthoquinone axial ligands as hypoxia-responsive a prodrug-like moieties (Prodrug-SiPc), is herein reported. With the help of computational methods, this study assessed the photophysical, photochemical and electrochemical redox properties of the Prodrug-SiPc to elucidate the relationship between material structure and properties. The attachment of the axial quinoid moieties endowed the Prodrug-SiPc with Type I/II photochemical and prodrug-like properties. Following liposomal encapsulation, the therapeutic efficacy of Prodrug-SiPc-liposomes was investigated against Michigan Cancer Foundation-7 (MCF-7) and Henrietta Lacks (Hela) cancer cells as in vitro cancer models and revealed that the as-synthesized Prodrug-SiPc-liposomes are potential photodynamic therapy (PDT) drug candidates. The Prodrug-SiPc-liposome takes full advantage of the hypoxic microenvironment of tumors - a side effect PDT - to trigger therapy, resulting in significantly enhanced efficacy compared to typical PDT. This work highlights the importance of multiple characteristics in designing new and effective photosensitizer candidates.

Hypoxia signaling in cancer: Implications for therapeutic interventions

Hypoxia is a persistent physiological feature of many different solid tumors and a key driver of malignancy, and in recent years, it has been recognized as an important target for cancer therapy. Hypoxia occurs in the majority of solid tumors due to a poor vascular oxygen supply that is not sufficient to meet the needs of rapidly proliferating cancer cells. A hypoxic tumor microenvironment (TME) can reduce the effectiveness of other tumor therapies, such as radiotherapy, chemotherapy, and immunotherapy. In this review, we discuss the critical role of hypoxia in tumor development, including tumor metabolism, tumor immunity, and tumor angiogenesis. The treatment methods for hypoxic TME are summarized, including hypoxia-targeted therapy and improving oxygenation by alleviating tumor hypoxia itself. Hyperoxia therapy can be used to improve tissue oxygen partial pressure and relieve tumor hypoxia. We focus on the underlying mechanisms of hyperoxia and their impact on current cancer therapies and discuss the prospects of hyperoxia therapy in cancer treatment.

A Cascade Nanoreactor of Metal-Protein-Polyphenol Capsule for Oxygen-Mediated Synergistic Tumor Starvation and Chemodynamic Therapy

Starvation therapy kills tumor cells via consuming glucose to cut off their energy supply. However, since glucose oxidase (GOx)-mediated glycolysis is oxygen-dependent, the cascade reaction based on GOx faces the challenge of a hypoxic tumor microenvironment. By decomposition of glycolysis production of H₂ O₂ into O₂ , starvation therapy can be enhanced, but chemodynamic therapy is limited. Here, a close-loop strategy for on demand H₂ O₂ and O₂ delivery, release, and recycling is proposed. The nanoreactor (metal-protein-polyphenol capsule) is designed by incorporating two native proteins, GOx and hemoglobin (Hb), in polyphenol networks with zeolitic imidazolate framework as sacrificial templates. Glycolysis occurs in the presence of GOx with O₂ consumption and the produced H₂ O₂ reacts with Hb to produce highly cytotoxic hydroxyl radicals (•OH) and methemoglobin (MHb) (Fenton reaction). Benefiting from the different oxygen carrying capacities of Hb and MHb, oxygen on Hb is rapidly released to supplement its consumption during glycolysis. Glycolysis and Fenton reactions are mutually reinforced by oxygen supply, consuming more glucose and producing more hydroxyl radicals and ultimately enhancing both starvation therapy and chemodynamic therapy. This cascade nanoreactor exhibits high efficiency for tumor suppression and provides an effective strategy for oxygen-mediated synergistic starvation therapy and chemodynamic therapy.

Emerging Sonodynamic Therapy-Based Nanomedicines for Cancer Immunotherapy

Cancer immunotherapy effect can be greatly enhanced by other methods to induce immunogenic cell death (ICD), which has profoundly affected immunotherapy as a highly efficient paradigm. However, these treatments have significant limitations, either by causing damage of the immune system or limited to superficial tumors. Sonodynamic therapy (SDT) can induce ICD to promote immunotherapy without affecting the immune system because of its excellent spatiotemporal selectivity and low side effects. Nevertheless, SDT is still limited by low reactive oxygen species yield and the complex tumor microenvironment. Recently, some emerging SDT-based nanomedicines have made numerous attractive and encouraging achievements in the field of cancer immunotherapy due to high immunotherapeutic efficiency. However, this cross-cutting field of research is still far from being widely explored due to huge professional barriers. Herein, the characteristics of the tumor immune microenvironment and the mechanisms of ICD are firstly systematically summarized. Subsequently, the therapeutic mechanism of SDT is fully summarized, and the advantages and limitations of SDT are discussed. The representative advances of SDT-based nanomedicines for cancer immunotherapy are further highlighted. Finally, the application prospects and challenges of SDT-based immunotherapy in future clinical translation are discussed.

Innovative strategies for photodynamic therapy against hypoxic tumor

Photodynamic therapy (PDT) is applied as a robust therapeutic option for tumor, which exhibits some advantages of unique selectivity and irreversible damage to tumor cells. Among which, photosensitizer (PS), appropriate laser irradiation and oxygen (O₂) are three essential components for PDT, but the hypoxic tumor microenvironment (TME) restricts the O₂ supply in tumor tissues. Even worse, tumor metastasis and drug resistance frequently happen under hypoxic condition, which further deteriorate the antitumor effect of PDT. To enhance the PDT efficiency, critical attention has been received by relieving tumor hypoxia, and innovative strategies on this topic continue to emerge. Traditionally, the O₂ supplement strategy is considered as a direct and effective strategy to relieve TME, whereas it is confronted with great challenges for continuous O₂ supply. Recently, O₂-independent PDT provides a brand new strategy to enhance the antitumor efficiency, which can avoid the influence of TME. In addition, PDT can synergize with other antitumor strategies, such as chemotherapy, immunotherapy, photothermal therapy (PTT) and starvation therapy, to remedy the inadequate PDT effect under hypoxia conditions. In this paper, we summarized the latest progresses in the development of innovative strategies to improve PDT efficacy against hypoxic tumor, which were classified into O₂-dependent PDT, O₂-independent PDT and synergistic therapy. Furthermore, the advantages and deficiencies of various strategies were also discussed to envisage the prospects and challenges in future study.

Versatile Red Blood Cells for Triple-Negative Breast Cancer Treatment via Stepwise Photoactivations

Phototherapies have many advantages for triple-negative breast cancer (TNBC) treatment. However, their effects are often limited by short blood circulation time, poor tumor selectivity and weak penetration of phototherapeutic agents, and tumor hypoxia. For overcoming these limitations, a versatile biomimetic system is developed based on red blood cells (RBCs). Photothermal agent new indocyanine green (IR820) is conjugated with the cell/tissue-penetrating TAT peptide and further efficiently encapsulated into the intact RBCs by crossing cell membranes to realize the long blood circulation. Meanwhile, cyclic RGD peptide (cRGD) is linked to the surfaces of RBCs through phospholipid insertion to obtain tumor vessel-targeting ability. Photosensitizer temoporfin (mTHPC) is next loaded into the membranes of RBCs by spontaneous transferring. The acquired biomimetic system (cRGD-RBC@mTHPC/TAT-IR820) exhibits potent photodynamic performance upon 652 nm laser irradiation with the facilitation of oxyhemoglobin, which could not only trigger TAT-IR820 release but also destroy tumor vessels. TAT-IR820 penetrates deeply into tumor tissue via the mediation of TAT peptide, exerting greatly promoted photothermal ablation against TNBC upon 808 nm laser irradiation. In situ generated tumor antigens further induce robust immune responses to suppress TNBC recurrence and metastasis. In summary, this study provides a versatile biomimetic system for comprehensive TNBC treatment via stepwise photodynamic and photothermal activations.