Photoactivatable Protherapeutic Nanomedicine for Cancer

Phototherapy in cancer treatment: strategies and challenges

Phototherapy has emerged as a promising modality in cancer treatment, garnering considerable attention for its minimal side effects, exceptional spatial selectivity, and optimal preservation of normal tissue function. This innovative approach primarily encompasses three distinct paradigms: Photodynamic Therapy (PDT), Photothermal Therapy (PTT), and Photoimmunotherapy (PIT). Each of these modalities exerts its antitumor effects through unique mechanisms-specifically, the generation of reactive oxygen species (ROS), heat, and immune responses, respectively. However, significant challenges impede the advancement and clinical application of phototherapy. These include inadequate ROS production rates, subpar photothermal conversion efficiency, difficulties in tumor targeting, and unfavorable physicochemical properties inherent to traditional phototherapeutic agents (PTs). Additionally, the hypoxic microenvironment typical of tumors complicates therapeutic efficacy due to limited agent penetration in deep-seated lesions. To address these limitations, ongoing research is fervently exploring innovative solutions. The unique advantages offered by nano-PTs and nanocarrier systems aim to enhance traditional approaches' effectiveness. Strategies such as generating oxygen in situ within tumors or inhibiting mitochondrial respiration while targeting the HIF-1α pathway may alleviate tumor hypoxia. Moreover, utilizing self-luminescent materials, near-infrared excitation sources, non-photoactivated sensitizers, and wireless light delivery systems can improve light penetration. Furthermore, integrating immunoadjuvants and modulating immunosuppressive cell populations while deploying immune checkpoint inhibitors holds promise for enhancing immunogenic cell death through PIT. This review seeks to elucidate the fundamental principles and biological implications of phototherapy while discussing dominant mechanisms and advanced strategies designed to overcome existing challenges-ultimately illuminating pathways for future research aimed at amplifying this intervention's therapeutic efficacy.

The Role of Open-Shell Organic Radical in Enhancing Anti-Tumor Photocatalysis Reaction of NIR Light-Activated Photosensitizer

Open-shell radical materials, which are characterized by unpaired electrons, have led to revolutionary breakthroughs in material science due to their unique optoelectronic properties. However, the involvement of organic radicals in photodynamic therapy (PDT) has rarely been reported or discussed. This work studies two photosensitizer analogs. 4AM-OS with extended π-conjugation exhibits open-shell radical characters and enhanced type-I photodynamic activity compared with closed-shell 2AM-CS. 4AM-OS displays the thermally accessible triplet-state character, resulting in more unpaired electrons delocalized along the π-conjugated backbone at higher temperatures. Accordingly, the temperature-dependent photodynamic activity of 4AM-OS confirms its association with the open-shell electronic structure. As the unpaired electrons in open-shell 4AM-OS are more delocalized and generate additional electronic energy states, photo-induced charge transfer is promoted to facilitate type-I photodynamic reactions. This observation addresses the challenge associated with near-infrared (NIR) photosensitizers, such as 4AM-OS, which often demonstrate low efficacy in PDT due to the limited energy provided by NIR light despite its superior tissue penetration depth. Overall, clarifying the beneficial role of organic radicals in photodynamic reactions will bring revolutionary breakthroughs to developing high-performance NIR photosensitizers and promoting the efficacy of PDT for deep-seated lesions.

Near-Infrared Chemiluminophore Switches Photodynamic Processes via Protein Complexation for Biomarker-Activatable Cancer Therapy

Despite the potential in cancer therapy, phototheranostic agents often face two challenges: limited diagnostic sensitivity due to tissue autofluorescence and suboptimal therapeutic efficacy due to the Type-II photodynamic process with the heavy oxygen reliance. In contrast, chemiluminescent theranostic agents without the requirement of real-time light excitation can address the issue of tissue autofluorescence, which however have been rarely reported for photodynamic therapy (PDT), not to mention less oxygen-dependent Type-I PDT. In this work, we synthesize near-infrared (NIR) chemiluminophores with the specific binding towards human serum albumin (HSA) to form chemiluminophore-protein complex for cancer detection and photodynamic therapy. Interestingly, after the complexation with HSA, the chemiluminescence (CL) intensities of chemiluminophores are enhanced by over 10-fold; meanwhile, the photodynamic process switches from Type-II (singlet-oxygen-generation dominated) to Type-I (superoxide anion and hydroxyl radical dominated), while the previously reported activated chemiluminophore with non-specific HSA binding can't switch photodynamic process. Based on the optimal chemiluminophore, a nitroreductase-activatable CL probe-protein complex is synthesized, which specially turns on its CL and Type-I PDT in hypoxic tumors for precision therapy. Thus, this study provides a complexation strategy to improve phototheranostic performance of chemiluminophores.

Biodegradable semiconducting polymer nanoparticles for phototheranostics

Semiconducting polymer nanoparticles (SPNs) have been widely applied for phototheranostics. However, the disadvantage of in vivo long-term metabolism greatly suppresses the clinical application of SPNs. To improve the metabolic rate and minimize the long-term toxicity of SPNs, biodegradable semiconducting polymers (BSPs), whose backbones may be degraded under certain conditions, have been designed. This review summarizes recent advances in BSP-constructed nanoparticles (BSPNs) for phototheranostics. BSPs are divided into two categories: conjugated backbone degradable BSPs (CBD-BSPs) and non-conjugated backbone degradable BSPs (NCBD-BSPs), based on the feature of chemical structure. The biological applications, including cancer imaging and combination therapy, of these BSPNs are described. Finally, the conclusion and future perspectives of this field are discussed.

Biomimetic Chlorosomes: Oxygen-Independent Photocatalytic Nanoreactors for Efficient Combination Photoimmunotherapy

Photocatalytic therapy for hypoxic tumors often suffers from inefficiencies due to its dependence on oxygen and the risk of uncontrolled activation. Inspired by the oxygen-independent and precisely regulated photocatalytic functions of natural light-harvesting chlorosomes, chlorosome-mimetic nanoreactors, termed Ru-Chlos, are engineered by confining the aggregation of photosensitive ruthenium-polypyridyl-silane monomers. These Ru-Chlos exhibit markedly enhanced photocatalytic performance compared to their monomeric counterparts under acidic conditions, while notably bypassing the consumption of oxygen or hydrogen peroxide. The photocatalytic activity of Ru-Chlos is finely tunable through light-responsive disassembly of the Ru-bridged matrix, with tunability governed by pre-irradiation duration. Utilization of Ru-Chlos loading prodrug [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS) for phototherapy facilitates the generation of toxic radicals (oxABTS) and the photocatalytic conversion of endogenous NADH to NAD+, inducing oxidative stress in hypoxic cancer cells. Simultaneously, the light-responsive degradation of Ru-Chlos produces Ru-based toxins that further contribute to the therapeutic effect. This dual-action mechanism elicits potent immunogenic cell death effects and significantly enhances antitumor efficacy with the aid of a PD-l blockade. These biomimetic chlorosomes highlight their potential to advance oxygen-independent photocatalytic nanoreactors with controlled activity for novel cancer photoimmunotherapy strategies.

Near-infrared photoactivatable three-in-one nanoagents to aggravate hypoxia and enable amplified photo-chemotherapy

Solid tumors create a hypoxic microenvironment and this character can be utilized for cancer therapy, but the hypoxia levels are insufficient to achieve satisfactory therapeutic benefits. Some tactics have been used to improve hypoxia, which however will cause side effects due to the uncontrolled drug release. We herein report near-infrared (NIR) photoactivatable three-in-one nanoagents (PCT) to aggravate tumor hypoxia and enable amplified photo-combinational chemotherapy. PCT are formed based on a thermal-responsive liposome nanoparticle containing three therapeutic agents: a hypoxia responsive prodrug tirapazamine (TPZ) for chemotherapy, a vascular targeting agent combretastatin A-4 (CA4) for vascular disturbance and a semiconducting polymer for both photodynamic therapy (PDT) and photothermal therapy (PTT). With NIR laser irradiation, PCT generate heat for PTT and destructing thermal-responsive liposomes to achieve activatable releases of TPZ and CA4. Moreover, PCT produce singlet oxygen (1O2) for PDT via consuming tumor oxygen. CA4 can disturb the blood vessels in tumor microenvironment to aggravate the hypoxic microenvironment, which results in the activation of TPZ for amplified chemotherapy. PCT thus enable PTT, PDT and hypoxia-amplified chemotherapy to afford a high therapeutic efficacy to almost absolutely eradicate subcutaneous 4 T1 tumors and effectively inhibit tumor metastases in lung and liver. This work presents an activatable three-in-one therapeutic nanoplatform with remotely controllable and efficient therapeutic actions to treat cancer.

Precision-engineered metal and metal-oxide nanoparticles for biomedical imaging and healthcare applications

The growing field of nanotechnology has witnessed numerous advancements over the past few years, particularly in the development of engineered nanoparticles. Compared with bulk materials, metal nanoparticles possess more favorable properties, such as increased chemical activity and toxicity, owing to their smaller size and larger surface area. Metal nanoparticles exhibit exceptional stability, specificity, sensitivity, and effectiveness, making them highly useful in the biomedical field. Metal nanoparticles are in high demand in biomedical nanotechnology, including Au, Ag, Pt, Cu, Zn, Co, Gd, Eu, and Er. These particles exhibit excellent physicochemical properties, including amenable functionalization, non-corrosiveness, and varying optical and electronic properties based on their size and shape. Metal nanoparticles can be modified with different targeting agents such as antibodies, liposomes, transferrin, folic acid, and carbohydrates. Thus, metal nanoparticles hold great promise for various biomedical applications such as photoacoustic imaging, magnetic resonance imaging, computed tomography (CT), photothermal, and photodynamic therapy (PDT). Despite their potential, safety considerations, and regulatory hurdles must be addressed for safe clinical applications. This review highlights advancements in metal nanoparticle surface engineering and explores their integration with emerging technologies such as bioimaging, cancer therapeutics and nanomedicine. By offering valuable insights, this comprehensive review offers a deep understanding of the potential of metal nanoparticles in biomedical research.

Supramolecular H-Aggregates of Squaraines with Enhanced Type I Photosensitization for Combined Photodynamic and Photothermal Therapy

Combined photodynamic and photothermal therapy (PDT and PTT) can achieve more superior therapeutic effects than the sole mode by maximizing the photon utilization, but there remains a significant challenge in the development of related single-molecule photosensitizers (PSs), particularly those with type I photosensitization. In this study, self-assembly of squaraine dyes (SQs) is shown to be a promising strategy for designing PSs for combined type I PDT and PTT, and a supramolecular PS (TPE-SQ7) has been successfully developed through subtle molecular design of an indolenine SQ, which can self-assemble into highly ordered H-aggregates in aqueous solution as well as nanoparticles (NPs). In contrast to the typical quenching effect of H-aggregates on reactive oxygen species (ROS) generation, our results encouragingly manifest that H-aggregates can enhance type I ROS (•OH) generation by facilitating the intersystem crossing process while maintaining a high PTT performance. Consequently, TPE-SQ7 NPs with ordered H-aggregates not only exhibit superior combined therapeutic efficacy than the well-known PS (Ce6) under both normoxic and hypoxic conditions but also have excellent biosafety, making them have important application prospects in tumor phototherapy and antibacterial fields. This study not only proves that the supramolecular self-assembly of SQs is an effective strategy toward high-performance PSs for combined type I PDT and PTT but also provides a different understanding of the effect of H-aggregates on the PDT performance.

Triphenylamine Sensitized 8-Dimethylaminoquinoline: An Efficient Two-Photon Caging Group for Intracellular Delivery

Triphenylamine-sensitized 8-dimethylaminoquinoline (TAQ) probes showed fair two-photon absorption and fragmentation cross sections in releasing kainate and GABA ligands. The water-soluble PEG and TEG-analogs allowed cell internalization and efficient light-gated liberation of the rhodamine reporter under UV and two-photon (NIR) irradiation conditions.

Recent advances for enhanced photodynamic therapy: from new mechanisms to innovative strategies

Photodynamic therapy (PDT) has been developed as a potential cancer treatment approach owing to its non-invasiveness, spatiotemporal control and limited side effects. Currently, great efforts have been made to improve the PDT effect in terms of safety and efficiency. In this review, we highlight recent advances in innovative strategies for enhanced PDT, including (1) the development of novel radicals, (2) design of activatable photosensitizers based on the TME and light, and (3) photocatalytic NADH oxidation to damage the mitochondrial electron transport chain. Additionally, the new mechanisms for PDT are also presented as an inspiration for the design of novel PSs. Finally, we discuss the current challenges and future prospects in the clinical practice of these innovative strategies. It is hoped that this review will provide a new angle for understanding the relationship between the intratumoural redox environment and PDT mechanisms, and new ideas for the future development of smart PDT systems.

Photosensitizer-Amplified Antimicrobial Materials for Broad-Spectrum Ablation of Resistant Pathogens in Ocular Infections

The emergence of multidrug resistant (MDR) pathogens and the scarcity of new potent antibiotics and antifungals are one of the biggest threats to human health. Antimicrobial photodynamic therapy (aPDT) combines light and photosensitizers to kill drug-resistant pathogens; however, there are limited materials that can effectively ablate different classes of infective pathogens. In the present work, a new class of benzodiazole-paired materials is designed as highly potent PDT agents with broad-spectrum antimicrobial activity upon illumination with nontoxic light. The results mechanistically demonstrate that the energy transfer and electron transfer between nonphotosensitive and photosensitive benzodiazole moieties embedded within pathogen-binding peptide sequences result in increased singlet oxygen generation and enhanced phototoxicity. Chemical optimization renders PEP3 as a novel PDT agent with remarkable activity against MDR bacteria and fungi as well as pathogens at different stages of development (e.g., biofilms, spores, and fungal hyphae), which also prove effective in an ex vivo porcine model of microbial keratitis. The chemical modularity of this strategy and its general compatibility with peptide-based targeting agents will accelerate the design of highly photosensitive materials for antimicrobial PDT.

A Synergistic Chemoimmunotherapy System Leveraging PD-L1 Blocking and Bioorthogonal Prodrug Activation

Novel strategies to facilitate tumor-specific drug delivery and restore immune attacks remain challenging in overcoming the current limitations of chemoimmunotherapy. An antitumor chemoimmunotherapy system comprising bioorthogonal reaction-ready group tetrazine (TZ) modified with an anti-PD-L1 antibody (αPD-L1TZ) and TZ-activatable prodrug vinyl ether-doxorubicin (DOX-VE) for self-reinforced anti-tumor chemoimmunotherapy is proposed. The αPD-L1TZ effectively disrupts the PD-L1/PD-1 interaction and activates the DOX prodrug in situ through the bioorthogonal click reaction of TZ and VE. Conversely, the activated DOX upregulates PD-L1 on the surface of tumor cells, facilitating tumor accumulation of αPD-L1TZ and enhancing DOX-VE activation. Furthermore, the activated DOX-induced immunogenic cell death of tumor cells, substantially improving the response efficiency of αPD-L1 in an immune-suppressive tumor microenvironment. Thus, PD-L1 blocking and bioorthogonal in situ prodrug activation synergistically enhance the antitumor efficacy of the chemoimmunotherapy system. Therefore, the system significantly enhances αPD-L1 tumor accumulation and prodrug activation and induces a robust immunological memory effect to prevent tumor recurrence and metastasis. Thus, a feasible chemoimmunotherapy combination regimen is presented.

Degradable bifunctional phototherapy composites based on upconversion nanoparticle-metal phenolic network for multimodal tumor therapy in the near-infrared biowindow

Phototherapy has garnered increasing attention as it allows for precise treatment of tumor sites with its accurate spatiotemporal control. In this study, we have successfully synthesized degradable bifunctional phototherapy agents (UCNPs@mSiO2@MPN-MC540/DOX) based on upconversion nanoparticle (UCNPs) and metal phenolic network (MPN), serving as a novel nanoplatform for multimodal tumor treatment in the near-infrared (NIR) biological window. To address the issue of low light penetration depth, the UCNPs we synthesized exhibited efficient light conversion ability under 808 nm laser irradiation to activate the photosensitizer Merocyanine 540 (MC540) for photodynamic therapy. Simultaneously, the 808 nm NIR light can also excite the MPN layer to achieve photothermal therapy for tumors. Additionally, the MPN layer possesses the capability of self-degradation under weakly acidic conditions. Within the tumor microenvironment, the MPN layer gradually degrades, facilitating the controlled release of the chemotherapy drug doxorubicin (DOX), thus achieving pH-responsive drug release and reducing the side effects of chemotherapy. This study provides an example of NIR-excited multimodal tumor treatment and pH-responsive drug release, offering a therapy model for precise tumor therapy.

Molecule engineering strategy of toll-like receptor 7/8 agonists designed for potentiating immune stimuli activation

Toll-like receptor 7/8 (TLR-7/8) agonists serve as a promising class of pattern recognition receptors that effectively evoke the innate immune response, making them promising immunomodulatory agents for tumor immunotherapy. However, the uncontrollable administration of TLR-7/8 agonists frequently leads to the occurrence of severe immune-related adverse events (irAEs). Thus, it is imperative to strategically design tumor-microenvironment-associated biomarkers or exogenous stimuli responsive TLR-7/8 agonists in order to accurately evaluate and activate innate immune responses. No comprehensive elucidation has been documented thus far regarding TLR-7/8 immune agonists that are specifically engineered to enhance immune activation. In this feature article, we provide an overview of the advancements in TLR-7/8 agonists, aiming to enhance the comprehension of their mechanisms and promote the clinical progression through nanomedicine strategies. The current challenges and future directions of cancer immunotherapy are also discussed, with the hope that this work will inspire researchers to explore innovative applications for triggering immune responses through TLR-7/8 agonists.

Dual-enzyme decorated semiconducting polymer nanoagents for second near-infrared photoactivatable ferroptosis-immunotherapy

Enzymes provide a class of potential options to treat cancer, while the precise regulation of enzyme activities for effective and safe therapeutic actions has been poorly reported. Dual-enzyme decorated semiconducting polymer nanoagents for second near-infrared (NIR-II) photoactivatable ferroptosis-immunotherapy are reported in this study. Such nanoagents (termed SPHGA) consist of hemoglobin (Hb)-based semiconducting polymer (SP@Hb), adenosine deaminase (ADA) and glucose oxidase (GOx) with loadings in a thermal-responsive nanoparticle shell. NIR-II photoactivation of SPHGA results in the generation of heat to trigger on-demand releases of two enzymes (ADA and GOx) via destroying the thermal-responsive nanoparticle shells. In the tumor microenvironment, GOx oxidizes glucose to form hydrogen peroxide (H2O2), which promotes the Fenton reaction of iron in SP@Hb, resulting in an enhanced ferroptosis effect and immunogenic cell death (ICD). In addition, ADA degrades high-level adenosine to reverse the immunosuppressive microenvironment, thus amplifying antitumor immune responses. Via NIR-II photoactivatable ferroptosis-immunotherapy, SPHGA shows an improved effect to absolutely remove bilateral tumors and effectively suppress tumor metastases in subcutaneous 4T1 breast cancer models. This study presents a dual-enzyme-based nanoagent with controllable therapeutic actions for effective and precise cancer therapy.

Dual-Modality Imaging-Guided Manganese-Based Nanotransformer for Enhanced Gas-Photothermal Therapy Combined Immunotherapeutic Strategy Against Triple-Negative Breast Cancer

Activating the stimulator of the interferon gene (STING) is a promising immunotherapeutic strategy for converting "cold" tumor microenvironment into "hot" one to achieve better immunotherapy for malignant tumors. Herein, a manganese-based nanotransformer is presented, consisting of manganese carbonyl and cyanine dye, for MRI/NIR-II dual-modality imaging-guided multifunctional carbon monoxide (CO) gas treatment and photothermal therapy, along with triggering cGAS-STING immune pathway against triple-negative breast cancer. This nanosystem is able to transfer its amorphous morphology into a crystallographic-like formation in response to the tumor microenvironment, achieved by breaking metal-carbon bonds and forming coordination bonds, which enhances the sensitivity of magnetic resonance imaging. Moreover, the generated CO and photothermal effect under irradiation of this nanotransformer induce immunogenic death of tumor cells and release damage-associated molecular patterns. Simultaneously, the Mn acts as an immunoactivator, potentially stimulating the cGAS-STING pathway to augment adaptive immunity, resulting in promoting the secretion of type I interferon, the proliferation of cytotoxic T lymphocytes and M2-macrophages repolarization. This nanosystem-based gas-photothermal treatment and immunoactivating therapy synergistic effect exhibit excellent antitumor efficacy both in vitro and in vivo, reducing the risk of triple-negative breast cancer recurrence and metastasis; thus, this strategy presents great potential as multifunctional immunotherapeutic agents for cancer treatment.

A red blood cell-derived bionic microrobot capable of hierarchically adapting to five critical stages in systemic drug delivery

The tumour-targeting efficiency of systemically delivered chemodrugs largely dictates the therapeutic outcome of anticancer treatment. Major challenges lie in the complexity of diverse biological barriers that drug delivery systems must hierarchically overcome to reach their cellular/subcellular targets. Herein, an "all-in-one" red blood cell (RBC)-derived microrobot that can hierarchically adapt to five critical stages during systemic drug delivery, that is, circulation, accumulation, release, extravasation, and penetration, is developed. The microrobots behave like natural RBCs in blood circulation, due to their almost identical surface properties, but can be magnetically manipulated to accumulate at regions of interest such as tumours. Next, the microrobots are "immolated" under laser irradiation to release their therapeutic cargoes and, by generating heat, to enhance drug extravasation through vascular barriers. As a coloaded agent, pirfenidone (PFD) can inhibit the formation of extracellular matrix and increase the penetration depth of chemodrugs in the solid tumour. It is demonstrated that this system effectively suppresses both primary and metastatic tumours in mouse models without evident side effects, and may represent a new class of intelligent biomimicking robots for biomedical applications.

H2O2-triggered controllable carbon monoxide delivery for photothermally augmented gas therapy

Carbon monoxide (CO) gas therapy has shown great potential as a very promising approach in the ongoing fight against tumors. However, delivering unstable CO to the tumor site and safely releasing it for maximum efficacy still have unsatisfactory outcomes. In this study, we've developed nanotheranostics (IN-DPPCO NPs) based on conjugated polymer IN-DPP and carbon monoxide (CO) carrier polymer mPEG(CO) for photothermal augmented gas therapy. The IN-DPPCO NPs can release CO with the hydrogen peroxide (H2O2) overexpressed in the tumor microenvironment. Meanwhile, IN-DPPCO NPs exhibit strong absorption in the near-infrared window, showing a high photothermal conversion efficiency of up to 41.5% under 808 nm laser irradiation. In vitro and in vivo experiments demonstrate that these nanotheranostics exhibit good biocompatibility. Furthermore, the synergistic CO/photothermal therapy shows enhanced therapeutic efficacy compared to gas therapy alone. This work highlights the great promise of conjugated polymer nanoparticles as versatile nanocarriers for spatiotemporally controlled and on-demand delivery of gaseous messengers to achieve precision cancer theranostics.

Dynamic immuno-nanomedicines in oncology

Anti-cancer therapeutics have achieved significant advances due to the emergence of immunotherapies that rely on the identification of tumors by the patients' immune system and subsequent tumor eradication. However, tumor cells often escape immunity, leading to poor responsiveness and easy tolerance to immunotherapy. Thus, the potentiated anti-tumor immunity in patients resistant to immunotherapies remains a challenge. Reactive oxygen species-based dynamic nanotherapeutics are not new in the anti-tumor field, but their potential as immunomodulators has only been demonstrated in recent years. Dynamic nanotherapeutics can distinctly enhance anti-tumor immune response, which derives the concept of the dynamic immuno-nanomedicines (DINMs). This review describes the pivotal role of DINMs in cancer immunotherapy and provides an overview of the clinical realities of DINMs. The preclinical development of emerging DINMs is also outlined. Moreover, strategies to synergize the antitumor immunity by DINMs in combination with other immunologic agents are summarized. Last but not least, the challenges and opportunities related to DINMs-mediated immune responses are also discussed.

Semiconducting Polymer Nanospherical Nucleic Acid Probe for Transcriptomic Imaging of Cancer Chemo-Immunotherapy

Real-time in vivo imaging of RNA can enhance the understanding of physio-pathological processes. However, most nucleic acid-based sensors have poor resistance to nucleases and limited photophysical properties, making them suboptimal for this purpose. To address this, a semiconducting polymer nanospherical nucleic acid probe (SENSE) for transcriptomic imaging of cancer immunity in living mice is developed. SENSE comprises a semiconducting polymer (SP) backbone covalently linked with recognition DNA strands, which are complemented by dye-labeled signal DNA strands. Upon detection of targeted T lymphocyte transcript (Gzmb: granzyme B), the signal strands are released, leading to a fluorescence enhancement correlated to transcript levels with superb sensitivity. The always-on fluorescence of the SP core also serves as an internal reference for tracking SENSE uptake in tumors. Thus, SENSE has the dual-signal channel that enables ratiometric imaging of Gzmb transcripts in the tumor of living mice for evaluating chemo-immunotherapy; moreover, it has demonstrated sensitivity and specificity comparable to flow cytometry and quantitative polymerase chain reaction,  yet offering a faster and simpler means of T cell detection in resected tumors. Therefore, SENSE represents a promising tool for in vivo RNA imaging.

Near-Infrared Light-Controlled MicroRNA-21-Loaded Upconversion Nanoparticles to Promote Bone Formation in the Midpalatal Suture

Rapid maxillary expansion (RME) is a common therapy for maxillary transverse deficiency. However, relapses after RME usually occur because of insufficient bone formation. MicroRNA-21 (miR-21) was reported as an important post-transcriptional modulator for osteogenesis. Herein, a photocontrolled miR-21 (PC-miR-21)-loaded nanosystem using upconversion nanoparticles (UCNPs) modified with poly(ether imide) (PEI), i.e., UCNPs@PEI@PC-miR-21, was constructed to promote bone formation in the midpalatal suture. UCNPs@PEI was constructed as the light transducer and delivery carrier. The UCNPs@PEI@PC-miR-21 nanocomplexes have good aqueous dispersibility and biocompatibility. The in vitro cell experiment suggested that UCNPs@PEI could protect PC-miR-21 from biodegradation and release PC-miR-21 into the cytoplasm under near-infrared light (NIR) irradiation. Furthermore, UCNPs@PEI@PC-miR-21 upregulated the expression of the osteogenic key markers, ALP, RUNX2, and COL1A1, at the levels of both genes and proteins. Besides, the results of the in vivo RME mice models further corroborated that photocontrollable UCNPs@PEI@PC-miR-21 accelerated bone formation with upregulating osteogenic markers of ALP, RUNX2, and osteoprotegerin and inducing fewer osteoclasts formation. In conclusion, UCNPs@PEI@PC-miR-21 nanoparticles with a NIR light could facilitate the remote and precise delivery of exogenous miR-21 to the midpalatal suture to promote bone formation during RME. This work represents a cutting-edge approach of gene therapy to promote osteogenesis in the midpalatal suture during RME and provides a frontier scientific basis for later clinical treatment.

Ultrasmall Cortex Moutan Nanoclusters for the Therapy of Pneumonia and Colitis

Infectious pneumonia and colitis are hard to be treated due to tissue infection, mucosal immune disorders, and dysbacteriosis. Although conventional nanomaterials can eliminate infection, they also damage normal tissues and intestinal flora. Herein, this work reports bactericidal nanoclusters formed through self-assembly for efficient treatment of infectious pneumonia and enteritis. The ultrasmall (about 2.3 nm) cortex moutan nanoclusters (CMNCs) has excellent antibacterial, antiviral, and immune regulation activity. The formation of nanoclusters is analyzed from the molecular dynamics mainly through the binding between polyphenol structures through hydrogen bonding and ππ stacking interaction. CMNCs have enhanced tissue and mucus permeability ability compared with natural CM. CMNCs precisely targeted bacteria due to polyphenol-rich surface structure and inhibited broad spectrum of bacteria. Besides, they killed H1N1 virus mainly through the inhibition of the neuraminidase. These CMNCs are effective in treating infectious pneumonia and enteritis relative to natural CM. In addition, they can be used for adjuvant colitis treatment by protecting colonic epithelium and altering the composition of gut microbiota. Therefore, CMNCs showed excellent application and clinical translation prospects in the treatment of immune and infectious diseases.

NIR-II Absorbing Conjugated Polymer Nanotheranostics for Thermal Initiated NO Enhanced Photothermal Therapy

Photothermal therapy (PTT) has received constant attention as a promising cancer treatment. However, PTT-induced inflammation can limit its effectiveness. To address this shortcoming, we developed second near-infrared (NIR-II) light-activated nanotheranostics (CPNPBs), which include a thermosensitive nitric oxide (NO) donor (BNN6) to enhance PTT. Under a 1064 nm laser irradiation, the conjugated polymer in CPNPBs serves as a photothermal agent for photothermal conversion, and the generated heat triggers the decomposition of BNN6 to release NO. The combination of hyperthermia and NO generation under single NIR-II laser irradiation allows enhanced thermal ablation of tumors. Consequently, CPNPBs can be exploited as potential candidates for NO-enhanced PTT, holding great promise for their clinical translational development.

Schottky Junction Nanozyme Based on Mn-Bridged Co-Phthalocyanines and Ti3C2Tx Nanosheets Boosts Integrative Type I and II Photosensitization for Multimodal Cancer Therapy

Cancer phototheranostics have the potential for significantly improving the therapeutic effectiveness, as it can accurately diagnose and treat cancer. However, the current phototheranostic platforms leave much to be desired and are often limited by tumor hypoxia. Herein, a Schottky junction nanozyme has been established between a manganese-bridged cobalt-phthalocyanines complex and Ti₃C₂T_x MXene nanosheets (CoPc-Mn/Ti₃C₂T_x), which can serve as an integrative type I and II photosensitizer for enhancing cancer therapeutic efficacy via a photoacoustic imaging-guided multimodal chemodynamic/photothermal/photodynamic therapy strategy under near-infrared (808 nm) light irradiation. The Schottky junction not only possessed a narrow-bandgap, enhanced electron-hole separation ability and exhibited a potent redox potential but also enabled improved H₂O₂ and O₂ supplying performances in vitro. Accordingly, the AS1411 aptamer-immobilized CoPc-Mn/Ti₃C₂T_x nanozyme illustrated high accuracy and excellent anticancer efficiency through a multimodal therapy strategy in in vitro and in vivo experiments. This work presents a valuable method for designing and constructing a multifunctional nanocatalytic medicine platform for synergistic cancer therapy of solid tumors.

Boron Dopants in Red-Emitting B and N Co-Doped Carbon Quantum Dots Enable Targeted Imaging of Lysosomes

Lysosomes are of great significance to cell growth, metabolism, and survival, as they independently maintain acidity and regulate various balances in cells. Therefore, it is essential to develop advanced probes for lysosome visualization and live tracking. Herein, a type of lysosome-targeting probe based on boron (B) and nitrogen (N) co-doped carbon quantum dots (B/N-CQDs) is presented, which exhibits red emission at 618 nm, high quantum yield (28%), and excellent fluorescence stability (97% at 1 h). These B/N-CQDs are prepared by a novel and green solid-state reaction and purified using a simple extraction process without additional chemical modifications. It is found that the boron dopants in the structure play a crucial role in the resultant lysosome-specific targeting property through borate esterification between boronic acid groups in the sample and diol structures in glycoproteins. This can be applied as a powerful tool for cell apoptosis, necrosis, and endosomal escape tracking. This work not only offers a new concept for targeted subcellular probe designs via chemical doping but also demonstrates the feasibility of these tools for analyzing complex cellular physiological activities.

Approved Nanomedicine against Diseases

Nanomedicine is a branch of medicine using nanotechnology to prevent and treat diseases. Nanotechnology represents one of the most effective approaches in elevating a drug's treatment efficacy and reducing toxicity by improving drug solubility, altering biodistribution, and controlling the release. The development of nanotechnology and materials has brought a profound revolution to medicine, significantly affecting the treatment of various major diseases such as cancer, injection, and cardiovascular diseases. Nanomedicine has experienced explosive growth in the past few years. Although the clinical transition of nanomedicine is not very satisfactory, traditional drugs still occupy a dominant position in formulation development, but increasingly active drugs have adopted nanoscale forms to limit side effects and improve efficacy. The review summarized the approved nanomedicine, its indications, and the properties of commonly used nanocarriers and nanotechnology.

Aspirin-Loaded Cross-Linked Lipoic Acid Nanodrug Prevents Postoperative Tumor Recurrence by Residual Cancer Cell Killing and Inflammatory Microenvironment Improvement

In addition to residual cancer cells, the surgery resection-induced hyperinflammatory microenvironment is a key factor that leads to postsurgical cancer recurrence. Herein, we developed a dual-functional nanodrug Asp@cLANVs for postsurgical recurrence inhibition by loading the classical anti-inflammatory drug aspirin (Asp) into cross-linked lipoic acid nanovesicles (cLANVs). The Asp@cLANVs can not only kill residual cancer cells at the doses comparable to common cytotoxic drugs by synergistic interaction between Asp and cLANVs, but also improve the postsurgical inflammatory microenvironment by their strongly synergistic anti-inflammation activity between Asp and cLANVs. Using mice bearing partially removed NCI-H460 tumors, we found that Asp@cLANVs gave a much lower recurrence rate (33.3%) compared with the first-line cytotoxic drug cisplatin (100%), and no mice died for at least 60 days after Asp@cLANV treatment while no mouse survived beyond day 43 in the cisplatin group. This dual-functional nanodrug constructs the first example that combines residual cancer cell killing and postoperative inflammation microenvironment improvement to suppress postsurgical cancer recurrence.

Bimetallic Nanomaterials: A Promising Nanoplatform for Multimodal Cancer Therapy

Bimetallic nanomaterials (BMNs) composed of two different metal elements have certain mixing patterns and geometric structures, and they often have superior properties than monometallic nanomaterials. Bimetallic-based nanomaterials have been widely investigated and extensively used in many biomedical fields especially cancer therapy because of their unique morphology and structure, special physicochemical properties, excellent biocompatibility, and synergistic effect. However, most reviews focused on the application of BMNs in cancer diagnoses (sensing, and imaging) and rarely mentioned the application of the treatment of cancer. The purpose of this review is to provide a comprehensive perspective on the recent progress of BNMs as therapeutic agents. We first introduce and discuss the synthesis methods, intrinsic properties (size, morphology, and structure), and optical and catalytic properties relevant to cancer therapy. Then, we highlight the application of BMNs in cancer therapy (e.g., drug/gene delivery, radiotherapy, photothermal therapy, photodynamic therapy, enzyme-mediated tumor therapy, and multifunctional synergistic therapy). Finally, we put forward insights for the forthcoming in order to make more comprehensive use of BMNs and improve the medical system of cancer treatment.

Riboflavin-Promoted In Situ Photoactivation of Dihydroalkaloid Prodrugs for Cancer Therapy

Cancer therapies usually suffer from poor targeting ability and serious side effects. Photoactivatable cancer therapy has the significant advantage of a high spatiotemporal resolution, but most photoactivatable prodrugs require decoration with stoichiometric photocleavable groups, which are only responsive to ultraviolet irradiation and suffer from low reaction efficiency. To tackle these challenges, we herein propose a photoactivation strategy with biogenic riboflavin as the photosensitizer to promote the in situ transformation of noncytotoxic dihydroalkaloid prodrugs dihydrochelerythrine (DHCHE), dihydrosanguinarine (DHSAN), and dihydronitidine (DHNIT) into anticancer alkaloid drugs chelerythrine (CHE), sanguinarine (SAN), and nitidine (NIT), respectively, which can efficiently kill cancer cells and inhibit in vivo tumor growth. Meanwhile, the photoactivatable transformation can be in situ monitored by green-to-red fluorescence conversion, which will contribute to easy controlling of the therapeutic dose. The proposed photoactivatable transformation mechanism was also explored by density functional theory (DFT) calculations. We believe this riboflavin-promoted and imaging-guided photoactivation strategy is promising for precise cancer therapy.

Recent advances in developing active targeting and multi-functional drug delivery systems via bioorthogonal chemistry

Bioorthogonal chemistry reactions occur in physiological conditions without interfering with normal physiological processes. Through metabolic engineering, bioorthogonal groups can be tagged onto cell membranes, which selectively attach to cargos with paired groups via bioorthogonal reactions. Due to its simplicity, high efficiency, and specificity, bioorthogonal chemistry has demonstrated great application potential in drug delivery. On the one hand, bioorthogonal reactions improve therapeutic agent delivery to target sites, overcoming off-target distribution. On the other hand, nanoparticles and biomolecules can be linked to cell membranes by bioorthogonal reactions, providing approaches to developing multi-functional drug delivery systems (DDSs). In this review, we first describe the principle of labeling cells or pathogenic microorganisms with bioorthogonal groups. We then highlight recent breakthroughs in developing active targeting DDSs to tumors, immune systems, or bacteria by bioorthogonal chemistry, as well as applications of bioorthogonal chemistry in developing functional bio-inspired DDSs (biomimetic DDSs, cell-based DDSs, bacteria-based and phage-based DDSs) and hydrogels. Finally, we discuss the difficulties and prospective direction of bioorthogonal chemistry in drug delivery. We expect this review will help us understand the latest advances in the development of active targeting and multi-functional DDSs using bioorthogonal chemistry and inspire innovative applications of bioorthogonal chemistry in developing smart DDSs for disease treatment.

Recent Advances in Light-Controlled Activation of Pt(IV) Prodrugs

Pt(IV) prodrugs remain one of the most promising alternatives to conventional Pt(II) therapy due to their versatility in axial ligand choice and delayed mode of action. Selective activation from an external source is especially attractive due to the opportunity to control the activity of an antitumor drug in space and time and avoid damage to normal tissues. In this review, we discuss recent advances in photoabsorber-mediated photocontrollable activation of Pt(IV) prodrugs. Two main approaches developed are the focus of the review. The first one is the photocatalytic strategy based on the flavin derivatives that are not covalently bound to the Pt(IV) substrate. The second one is the conjugation of photoactive molecules with the Pt(II) drug via axial position, yielding dual-action Pt(IV) molecules capable of the controllable release of Pt(II) cytotoxic agents. Thus, Pt(IV) prodrugs with a light-controlled mode of activation are non-toxic in the absence of light, but show high antiproliferative activity when irradiated. The susceptibility of Pt(IV) prodrugs to photoreduction, photoactivation mechanisms, and biological activity is considered in this review.

Multifunctional Mesoporous Hollow Cobalt Sulfide Nanoreactors for Synergistic Chemodynamic/Photodynamic/Photothermal Therapy with Enhanced Efficacy

The unique tumor microenvironment (TME) characteristic of severe hypoxia, overexpressed intracellular glutathione (GSH), and elevated hydrogen peroxide (H₂O₂) concentration limit the anticancer effect by monotherapy. In this report, glucose oxidase (GOx)-encapsulated mesoporous hollow Co₉S₈ nanoreactors are constructed with the coverage of polyphenol diblock polymers containing poly(oligo(ethylene glycol) methacrylate) and dopamine moieties containing methacrylate polymeric block, which are termed as GOx@PCoS. After intravenous injection, tumor accumulation, and cellular uptake, GOx@PCoS deplete GSH by Co³⁺ ions. GOx inside the nanoreactors produce H₂O₂ via oxidation of glucose to enhance •OH-based chemodynamic therapy (CDT) through the Fenton-like reaction under the catalysis of Co²⁺. Moreover, Co³⁺ ions possess catalase activity to catalyze production of O₂ from H₂O₂ to relieve tumor hypoxia. Upon 808 nm laser irradiation, GOx@PCoS exhibit photothermal and photodynamic effects with a high photothermal conversion efficiency (45.06%) and generation capacity of the toxic superoxide anion (•O₂^-) for photothermal therapy (PTT) and photodynamic therapy (PDT). The synergetic antitumor effects can be realized by GSH depletion, starvation, and combined CDT, PTT, and PDT with enhanced efficacy. Notably, GOx@PCoS can also be used as a magnetic resonance imaging (MRI) contrast agent to monitor the antitumor performance. Thus, GOx@PCoS show great potentials to effectively modulate TME and perform synergistic multimodal therapy.

Aggregation-Induced Emission Luminogens for Enhanced Photodynamic Therapy: From Organelle Targeting to Tumor Targeting

Photodynamic therapy (PDT) has attracted much attention in the field of anticancer treatment. However, PDT has to face challenges, such as aggregation caused by quenching of reactive oxygen species (ROS), and short 1O2 lifetime, which lead to unsatisfactory therapeutic effect. Aggregation-induced emission luminogen (AIEgens)-based photosensitizers (PSs) showed enhanced ROS generation upon aggregation, which showed great potential for hypoxic tumor treatment with enhanced PDT effect. In this review, we summarized the design strategies and applications of AIEgen-based PSs with improved PDT efficacy since 2019. Firstly, we introduce the research background and some basic knowledge in the related field. Secondly, the recent approaches of AIEgen-based PSs for enhanced PDT are summarized in two categories: (1) organelle-targeting PSs that could cause direct damage to organelles to enhance PDT effects, and (2) PSs with tumor-targeting abilities to selectively suppress tumor growth and reduce side effects. Finally, current challenges and future opportunities are discussed. We hope this review can offer new insights and inspirations for the development of AIEgen-based PSs for better PDT effect.

Bioorthogonal Click of Colloidal Gold Nanoparticles to Antibodies In vivo

Combining nanotechnology and bioorthogonal chemistry for theranostic strategies offers the possibility to develop next generation nanomedicines. These materials are thought to increase therapeutic outcome and improve current cancer management. Due to their size, nanomedicines target tumors passively. Thus, they can be used for drug delivery purposes. Bioorthogonal chemistry allows for a pretargeting approach. Higher target-to-background drug accumulation ratios can be achieved. Pretargeting can also be used to induce internalization processes or trigger controlled drug release. Colloidal gold nanoparticles (AuNPs) have attracted widespread interest as drug delivery vectors within the last decades. Here, we demonstrate for the first time the possibility to successfully ligate AuNPs in vivo to pretargeted monoclonal antibodies. We believe that this possibility will facilitate the development of AuNPs for clinical use and ultimately, improve state-of-the-art patient care.

The Study of Exosomes-Encapsulated mPEG-PLGA Polymer Drug-Loaded Particles for Targeted Therapy of Liver Cancer

The emergence of targeted drugs brings hope to patients with advanced liver cancer. However, due to the complex and diverse environment in the human body, the overall response rate of targeted drugs is not high. Therefore, how to efficiently deliver targeted drugs to tumor sites is a major challenge for current research. The project intends to construct mPEG-PLGA nanoparticles loaded with Sora and encapsulate them with exosomes for targeted therapy of hepatocellular carcinoma. mPEG-PLGA drug-loaded nanoparticles were prepared by the dialysis method and characterized by TEM and DLS. The obtained nanoparticles were incubated with the exosomes of liver cancer cells, and the exosomes-encapsulated drug-loaded nanoparticles (Exo-Sora-NPs) were obtained under pulsed ultrasound conditions, and they were characterized by Western blot, transmission electron microscopy (TEM), and dynamic light scattering (DLS). The toxic effect of Exo-Sora-NPs on liver cancer cells was detected by the CCK-8 experiment. The uptake efficiency of nanoparticles by liver cancer cells was detected by a confocal microscope. The accumulation and infiltration depth of nanomedicine in liver cancer tissues were observed by confocal microscope on frozen sections of liver cancer tissue after the H22 liver cancer subcutaneous tumor transplantation model was constructed. The tumor size, body weight, pathology, and serology analysis of mice were measured after administration. The mPEG-PLGA polymer drug-loaded particles encapsulated by exosomes have high targeting ability and biosafety. To a certain extent, they can target the drug to the tumor site with a smaller systemic response and have a highly effective killing effect on the tumor. Nanodrug-loaded particles encapsulated by exosomes have great potential as drug carriers.

Delivery process and effective design of vectors for cancer therapy

In recent years, the efficacy of nano-drugs has not been significantly better than that of the drugs themselves, mainly because nano-drugs enter the tumor vasculature, stay near the blood vessels, and cannot enter the tumor tissues or tumor cells to complete the drug delivery process. Although intratumor injection can significantly decrease this risk, the side effects are strong. The advent of drug delivery carrier materials offers an opportunity to avoid the side effects of systemic drug delivery and the damage caused by tumor resection, holding great promise for the future of cancer therapy. Here, we systematically review recent research advances in the classification of drug delivery carrier materials and the delivery process in drug delivery systems. This review is divided into several main sections, first, we summarize the classification of tumor drug carrier materials, including drug delivery vectors and gene delivery vectors, etc., which are introduced in detail, respectively. Then we describe the carrier materials to deliver the drug cascade and the transition pathways for drug delivery, including stabilization transitions, charge inversions, and size changes. Finally, we discuss the current design strategies and research progress of drug vectors and provide a summary and outlook. This review aims to summarize different drug delivery vehicles and delivery processes to provide ideas for effective cancer therapy.

Engineering Metal-Organic Framework Hybrid AIEgens with Tumor-Activated Accumulation and Emission for the Image-Guided GSH Depletion ROS Therapy

Aggregation-induced emission (AIE)-active luminogens (AIEgens) have demonstrated exciting potential for the application in cancer phototheranostics. However, simultaneously achieving tumor-activated bright emission, enhanced reactive oxygen species (ROS) generation, high tumor accumulation, and minimized ROS depletion remains challenging. Here, a metal-organic framework (MOF) hybrid AIEgen theranostic platform is designed, termed A-NUiO@DCDA@ZIF-Cu, composed of an AIEgen-loaded hydrophobic UiO-66 (A-NUiO@DCDA) core and a Cu-doped hydrophilic ZIF-8 (ZIF-Cu) shell. The fluorescence emission and therapeutic ROS activity of AIEgens are restrained during delivery. After uptake by tumor tissues, ZIF-Cu decomposition occurs in response to an acidic tumor microenvironment (TME), and the hydrophobic A-NUiO@DCDA cores self-assemble into large particles, extremely increasing the tumor accumulation of AIEgens. This results in enhanced fluorescence imaging (FLI) and highly improved ¹O₂ generation ability during photodynamic therapy (PDT). Meanwhile, the released Cu²⁺ reacts to glutathione (GSH) to generate Cu⁺, which provides an extra chemodynamic therapy (CDT) function through Fenton-like reactions with overexpressed H₂O₂, resulting in the GSH depletion-enhanced ROS therapy. As a result of these characteristics, the MOF hybrid AIEgens can selectively kill tumors with excellent efficacy.

"One Stone, Four Birds" Ion Engineering to Fabricate Versatile Core-Shell Organosilica Nanoparticles for Intelligent Nanotheranostics

Developing effective intelligent nanotheranostics is highly desirable for cancer treatment but remains challenging. In this study, an acidic tumor microenvironment-activated organosilica nanosystem, namely AD-Cu-DOX-HA, is straightforwardly constructed, which is composed of aggregation-induced emission (AIE)-active photosensitizer, copper ion-engineered aminosilica, direct coordination polymer of doxorubicin (DOX), and targeting component hyaluronic acid (HA). AD-Cu-DOX-HA is able to accurately distinguish cancer cells over normal cells; meanwhile, it simultaneously exhibits selective accumulation and copper ion-mediated rapid disassembly and turn-on fluorescence in tumor tissue, consequently achieving efficient tumor diagnosis and tumor-growth inhibition through fluorescence imaging-navigated synergetic photodynamic therapy, copper ion-mediated chemodynamic therapy, and DOX-enabled chemotherapy. This work thus brings fresh insight into the exploration of versatile theranostics and presents a momentous advance for potential clinical cancer treatment.

A Dual-Locked Activatable Phototheranostic Probe for Biomarker-Regulated Photodynamic and Photothermal Cancer Therapy

Activatable phototheranostics holds promise for precision cancer treatment owing to the "turn-on" signals and therapeutic effects. However, most activatable phototheranostic probes only possess photodynamic therapy (PDT) or photothermal therapy (PTT), which suffer from poor therapeutic efficacy due to deficient cellular oxygen and complex tumor microenvironment. We herein report a dual-locked activatable phototheranostic probe that activates near-infrared fluorescence (NIRF) signals in tumor, triggers PDT in response to a tumor-periphery biomarker, and switches from PDT to PTT upon detecting a tumor-core-hypoxia biomarker. This PDT-PTT auto-regulated probe exhibits complete tumor ablation under the photoirradiation of a single laser source by producing cytotoxic singlet oxygen at the tumor periphery and generating hyperthermia at tumor-core where is too hypoxic for PDT. This dual-locked probe represents a promising molecular design approach toward precise cancer phototheranostics.

Peptide-based supramolecular assembly drugs toward cancer theranostics

INTRODUCTION

: Peptide-based supramolecular self-assembly has been demonstrated to be a flexible approach for the fabrication of programmable de novo nanodrugs by employing synergistic or reciprocal intermolecular non-covalent interactions; this class of nanomaterials holds significant promise for clinical translation, especially as cancer theranostics.

AREAS COVERED

: In this review, we describe the concept of cancer theranostic drug assembly by employing non-covalent interactions. That is, molecular drugs are formulated into nanoscale and even microscale architectures by peptide-modulated self-assembly. A series of peptide-based supramolecular assembly drugs are discussed, with an emphasis on the relation between structural feature and theranostic performance.

EXPERT OPINION

: Molecular design, manipulation of non-covalent interactions and elucidation of structure-function relationships not only facilitate the implementation of supramolecular self-assembly principles in drug development, but also provide a new means for advancing anticancer nanostructured drugs toward clinical application.

One- and Two-Photon Activated Release of Oxaliplatin from a Pt(IV)-Functionalized Poly(phenylene ethynylene)

We report a water-soluble poly(phenylene ethynylene) (PPE-Pt(IV)) that is functionalized with oxidized oxaliplatin Pt(IV) units and its use for photoactivated chemotherapy. The photoactivation strategy is based on photoinduced electron transfer from the PPE backbone to oxaliplatin Pt(IV) as an electron acceptor; this process triggers the release of oxaliplatin, which is a clinically used anticancer drug. Mechanistic studies carried out using steady-state and time-resolved fluorescence spectroscopy coupled with picosecond-nanosecond transient absorption support the hypothesis that electron transfer triggers the drug release. Photoactivation is effective, producing oxaliplatin with a good chemical yield in less than 1 h of photolysis (400 nm, 5 mW cm-2). Photorelease of oxaliplatin from PPE-Pt(IV) can also be effected with two-photon excitation by using 100 fs pulsed light at 725 nm. Cytotoxicity studies using SK-OV-3 human ovarian cancer cells demonstrate that without photoactivation PPE-Pt(IV) is not cytotoxic at concentrations up to 10 μM in polymer repeating unit (PRU) concentration. However, following a short period of 460 nm irradiation, oxaliplatin is released from PPE-Pt(IV), resulting in cytotoxicity at concentrations as low as 2.5 μM PRU.

Carbonic anhydrase IX-targeted H-APBC nanosystem combined with phototherapy facilitates the efficacy of PI3K/mTOR inhibitor and resists HIF-1α-dependent tumor hypoxia adaptation

Background

Non-redundant properties such as hypoxia and acidosis promote tumor metabolic adaptation and limit anti-cancer therapies. The key to the adaptation of tumor cells to hypoxia is the transcriptional and stable expression of hypoxia-inducible factor-1 alpha (HIF-1α). The phosphorylation-activated tumorigenic signal PI3K/AKT/mTOR advances the production of downstream HIF-1α to adapt to tumor hypoxia. Studies have elucidated that acid favors inhibition of mTOR signal. Nonetheless, carbonic anhydrase IX (CAIX), overexpressed on membranes of hypoxia tumor cells with pH-regulatory effects, attenuates intracellular acidity, which is unfavorable for mTOR inhibition. Herein, a drug delivery nanoplatform equipped with dual PI3K/mTOR inhibitor Dactolisib (NVP-BEZ235, BEZ235) and CAIX inhibitor 4‐(2‐aminoethyl) benzene sulfonamide (ABS) was designed to mitigate hypoxic adaptation and improve breast cancer treatment.

Results

ABS and PEG-NH₂ were successfully modified on the surface of hollow polydopamine (HPDA), while BEZ235 and Chlorin e6 (Ce6) were effectively loaded with the interior of HPDA to form HPDA-ABS/PEG-BEZ235/Ce6 (H-APBC) nanoparticles. The release of BEZ235 from H-APBC in acid microenvironment could mitigate PI3K/mTOR signal and resist HIF-1α-dependent tumor hypoxia adaptation. More importantly, ABS modified on the surface of H-APBC could augment intracellular acids and enhances the mTOR inhibition. The nanoplatform combined with phototherapy inhibited orthotopic breast cancer growth while reducing spontaneous lung metastasis, angiogenesis, based on altering the microenvironment adapted to hypoxia and extracellular acidosis.

Conclusion

Taken together, compared with free BEZ235 and ABS, the nanoplatform exhibited remarkable anti-tumor efficiency, reduced hypoxia adaptation, mitigated off-tumor toxicity of BEZ235 and solved the limited bioavailability of BEZ235 caused by weak solubility.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01394-w.

Photothermal Conjugated Polymer Nanoparticles for Suppressing Breast Tumor Growth by Regulating TRPA1 Ion Channels

Cancer cells survive by relying on oxidative stress defense against the accumulation of reactive oxygen species (ROS) during tumor formation. ROS-sensitive TRPA1 ion channels are overexpressed in breast cancer cells and induce a large influx of Ca²⁺ which upregulates the anti-apoptotic pathway to lead breast cancer cells to produce oxidative stress defense and enhance the resistance to ROS related chemotherapy. Targeting and inhibiting the TRPA1 ion channels are critical for breaking down the oxidative stress defense system and overcoming cellular resistance. Here, near-infrared (NIR) light-responsive conjugated polymer nanoparticles are designed and prepared to promote apoptosis of breast cancer cells, reduce cell drug resistance and suppress tumor growth through the remote and precise regulation of TRPA1 ion channels. Upon 808 nm laser irradiation, the nanoparticles block the formation of Ca²⁺ /CaM complex and regulate the content of MCL-1 protein. Especially, the nanoparticles overcome drug resistance of cancer cells, therefore accelerating apoptosis of cancer cells and suppressing tumor growth in mice. Compared with carboplatin, the volume of tumor induced by NPs-H decreases by 54.1%. This work provides a strategy to disrupt the oxidative stress defense system and downregulate the antiapoptotic signaling pathway in cancer cells.

Ferrocene-Containing Nucleic Acid-Based Energy-Storage Nanoagent for Continuously Photo-Induced Oxidative Stress Amplification

Regulation of cellular oxidative stress plays a critical role in revealing the molecular mechanisms of cellular activities and thus is a potential strategy for tumor treatment. Optical methods have been employed for intelligent regulation of oxidative stress in tumor regions. However, long-time continuous irradiation inevitably causes damage to normal tissues. Herein, a ferrocene-containing nucleic acid-based energy-storage nanoagent was designed to achieve the continuous photo-regulation of cellular oxidative stress in the dark. Specifically, the photoenergy stored in the agent could convert effectively and accelerate Fenton-like reaction continuously, augmenting cellular oxidative stress. This nanoagent could also silence oxidative damage repair genes to further amplify oxidative stress. This strategy not only provides oxidative stress regulation for studying the molecular mechanisms of biological activities, but also offers a promising step toward tumor microenvironment modulation.

A Facile, Protein-Derived Supramolecular Theranostic Strategy for Multimodal-Imaging-Guided Photodynamic and Photothermal Immunotherapy In Vivo

Theranostic systems that permit both diagnosis and treatment in vivo are highly appealing means by which to meet the demands of precision medicine. However, most such systems remain subject to issues related to complex molecular design and synthesis, potential toxicity, and possible photoactivity changes. Herein, a novel supramolecular theranostic strategy involving biomarker protein activation (BPA) and a host-guest strategy is proposed. To exemplify BPA, a facile "one-for-all" nanotheranostic agent for both albumin detection and cancer treatment is demonstrated, which utilizes a nanoparticulate heavy-atom-free BODIPY dye derivative (B4 NPs). The fluorescence and photoactivity of BODIPY dyes are completely suppressed by aggregation-induced self-quenching in the nanoparticulate state. However, a Balb/c nude mouse model is used to confirm that following the disassembly of injected B4 NPs, BODIPY specifically binds albumin in vivo, accompanied by significantly enhanced biocompatibility and photothermal conversion efficiency. More importantly, this supramolecular host-guest BPA strategy enables the resultant nanoplatform to act as a facile and efficient strategy for photodynamic and photothermal immunotherapy.