Strategic Design of Conquering Hypoxia in Tumor for Advanced Photodynamic Therapy

AIEgen-self-assembled nanoparticles with anti-PD-L1 antibody functionalization realize enhanced synergistic photodynamic therapy and immunotherapy against malignant melanoma

Immune checkpoint inhibitors (ICIs) become integral in clinical practice, yet their application in cancer therapy is constrained by low overall response rates and the primary resistance of cancers to ICIs. Herein, this study proposes aggregation-induced emission (AIE)-based nanoparticles (NPs) for a more effective and synergistic approach combining immunotherapy and photodynamic therapy (PDT) to achieve higher responses than anti-PD-L1 monotherapy. The TBP@aPD-L1 NPs are constructed by functionalizing azide group-modified TBP-2 (TBP-N3) with anti-PD-L1 antibodies via the DBCO-S-S-PEG2000-COOH linker. The anti-PD-L1 target the tumor cells and promote the TBP-N3 accumulation in tumors for enhanced PDT. Notably, the TBP-N3, featuring aggregation-induced emission, boosts reactive oxygen species (ROS) generation through both type I and type II processes for enhanced PDT. The TBP@aPD-L1-mediated PDT induces more powerful effects of direct tumor cell-killing and further elicits effective immunogenic cell death (ICD), which exerts anti-tumor immunity by activating T cells for ICI treatment and reshapes the tumor immune microenvironment (TIME), thereby enhancing the efficacy of PD-L1 blockade of anti-PD-L1. Consequently, TBP@aPD-L1 NPs demonstrated significantly enhanced inhibition of tumor growth in the mouse model of malignant melanoma (MM). Our NPs act as a facile and effective drug delivery platform for enhanced immunotherapy combined with enhanced PDT in treating MM.

RGD peptide-conjugated polydopamine nanoparticles loaded with doxorubicin for combined chemotherapy and photothermal therapy in thyroid cancer

OBJECTIVE

To construct polydopamine (PDA)-based nanoparticles (NPs) for combined chemotherapy (CT) and photothermal therapy (PTT) of thyroid tumors by conjugating doxorubicin (DOX) via Schiff base reaction and decorating with RGD peptide.

METHODS

PDA NPs were synthesized using dopamine hydrochloride (DA) as the raw material and reacted with DOX-PEG-NH2 to obtain PDA-DOX NPs. Subsequently, RGD peptide was coupled with PDA-DOX NPs for modification. Their size, charge, and shape were characterized using DLS and SEM. The assembly of DOX was verified by ultraviolet-visible spectroscopy (UV-Vis), and the release efficiency of DOX under different pH conditions was calculated. The antitumor effect of RGD@PDA-DOX was validated in KTC-1 cells and tumor-bearing nude mice.

RESULTS

The prepared RGD@PDA-DOX exhibited excellent dispersion, stability, and biocompatibility. PDA-DOX possessed superior photothermal conversion efficiency, capable of rapidly elevating the solution temperature within 5 min. In vitro studies revealed that the inhibitory rate of RGD@PDA-DOX combined with 808 nm laser on KTC-1 cells reached 92% (p < 0.05). In vivo experiments demonstrated that RGD@PDA-DOX exhibits no cytotoxicity. The modification with RGD peptides enables RGD@PDA-DOX to target tumor regions and accumulate over an extended period. Additionally, RGD@PDA-DOX, when combined with an 808 nm laser, significantly inhibits tumor growth.

CONCLUSION

RGD@PDA-DOX can effectively accumulate in tumor regions and demonstrates excellent anti-tumor efficacy. It may serve as a feasible approach for the effective treatment of thyroid tumors, providing further evidence and data for clinical translation.

Photothermally Active Quantum Dots in Cancer Imaging and Therapeutics: Nanotheranostics Perspective

Cancer is becoming a global threat, as the cancerous cells manipulate themselves frequently, resulting in mutants and more abnormalities. Early-stage and real-time detection of cancer biomarkers can provide insight into designing cost-effective diagnostic and therapeutic modalities. Nanoparticle and quantum dot (QD)-based approaches have been recognized as clinically relevant methods to detect disease biomarkers at the molecular level. Over decades, as an emergent noninvasive approach, photothermal therapy has evolved to eradicate cancer. Moreover, various structures, viz., nanoparticles, clusters, quantum dots, etc., have been tested as bioimaging and photothermal agents to identify tumor cells selectively. Among them, QDs have been recognized as versatile probes. They have attracted enormous attention for imaging and therapeutic applications due to their unique colloidal stability, optical and physicochemical properties, biocompatibility, easy surface conjugation, scalable production, etc. However, a few critical concerns of QDs, viz., precise engineering for molecular imaging and sensing, selective interaction with the biological system, and their associated toxicity, restrict their potential intervention in curing cancer and are yet to be explored. According to the U.S. Food and Drug Administration (FDA), there is no specific regulation for the approval of nanomedicines. Therefore, these nanomedicines undergo the traditional drug, biological, and device approval process. However, the market survey of QDs is increasing, and their prospects in translational nanomedicine are very promising. From this perspective, we discuss the importance of QDs for imaging, sensing, and therapeutic usage pertinent to cancer, especially in its early stages. Moreover, we also discuss the rapidly growing translational view of QDs. The long-term safety studies and cellular interaction of these QDs could enhance their visibility and bring photothermally active QDs to the clinical stage and concurrently to FDA approval.

Catalase-positive Staphylococcus epidermidis based cryo-millineedle platform facilitates the photo-immunotherapy against colorectal cancer via hypoxia improvement

The synergistic anti-tumor impact of phototherapy and a cascading immune response are profoundly limited by hypoxia and a weakened immune response. Intravenous and intratumoral injection of therapeutic drugs also cause pain, rapid drug clearance and low utilization rates. Here, a novel cryo-millineedle platform for intratumoral delivery of a phototherapy system, S.epi@IR820, is developed in this work, combining the properties of Staphylococcus epidermidis (S. epidermidis) and IR820 for photo-immunotherapy of colorectal cancer. In this cryo-millineedle platform, S. epidermidis enhances the near-infrared absorption and light stability of IR820 and catalyzes the decomposition of H2O2 into O2 via an endogenous catalase to relieve tumor hypoxia, improve phototherapy and enhance immunogenic cell death (ICD). More interestingly, the native immunogenicity of S. epidermidis and ICD elicited by phototherapy achieved a potent anti-tumor immune response. To the best of our knowledge, this is the first study to utilize native S. epidermidis to relieve hypoxia and facilitate phototherapy. Both in vitro and in vivo experiments showed that the millineedle based phototherapy system can efficiently catalyse the decomposition of H2O2 into O2, facilitate phototherapeutic killing of CT26 tumor cells by S.epi@IR820 and enhance ICD, thus successfully activated the immune response and achieved the photo-immunotherapy against colorectal cancer. In conclusion, this study provides a novel strategy for enhanced anti-tumor efficiency of photo-immunotherapy, and develops an effective method for orthotopic administration of tumors.

Bypassing Ca2+ Influx for Antimetastasis Photodynamic Therapy via Robust Nucleus-Targeted Near-Infrared Cyanines

Hypoxia-induced tumor metastasis severely hinders the efficacy of photodynamic therapy (PDT) in cancer treatment. Current strategies predominantly offer palliative suppression of the HIF-1α pathway, emphasizing the urgent need for innovative PDT approaches to prevent metastasis from the outset. Our study revealed that typical PDT triggers an increase in cytoplasmic Ca2+ levels, activating HIF-1α, and that reducing Ca2+ levels can, in turn, mitigate metastasis. Considering cytoplasm's role in Ca2+ storage and regulation, we propose that PDT-induced metastasis can be addressed at its source by precise intracellular localization of photosensitizers (PSs). We developed near-infrared (NIR) cyanine PSs with inherent nucleus targeting capabilities. These PSs effectively inhibit cytoplasmic Ca2+ elevation and reduce HIF-1α activity upon irradiation, achieving remarkable antimetastatic effects in 4T1 tumors. Consequently, our findings highlight the pivotal role of Ca2+ in PDT-induced metastasis and provide a robust approach for circumventing metastasis from the outset using new nucleus-targeting organic PSs.

Triple-function porphyrin in glycopolymeric photosensitizers: from photoATRP to targeted PDT

Porphyrin derivatives serve as photocatalysts in reversible-deactivation radical polymerization and as photosensitizers in photodynamic therapy (PDT). Herein, a triple function porphyrin, ZnTPPC6Br, was synthesized as a photocatalyst and initiator for photoATRP. Oxygen-tolerant photoATRP produced fructose-based star-shaped glycopolymers as targeted photosensitizers for PDT. ZnTPPC6Br/CuII/PMDETA could synthesize polymer photosensitizers with predictable M n and low Đ. Mechanistic studies unveiled the transition of ZnTPPC6Br from a singlet excited state (1PC*) to a triplet excited state (3PC*), enabling the activator CuI/L generation and initiating photoATRP. The excess ligands facilitate return of the active species to the ground state, while the presence of DMSO assists in oxygen depletion. Three fructose-based monomers with different polymerizable groups (acrylated, methacrylated, and p-vinylbenzoated) were employed to scale up polymerization, yielding glycopolymeric photosensitizers post-deprotection. In vitro cellular studies showed enhanced PDT efficacy of glycopolymeric photosensitizers against MCF-7 cells, attributed to specific GLUT5 binding for targeted endocytosis, highlighting their potential for precise cancer treatment compared to L929 cells. The multifunctional capabilities of ZnTPPC6Br are anticipated to serve as a strategic avenue for the advancement of polymer photosensitizers with potential PDT applications.

Light-Driven Green-Fabricated Artificial Intelligence-Enabled Micro/Nanorobots for Multimodal Phototherapeutic Management of Bladder Cancer

Combination therapy based on precise phototherapies combined with immune modulation provides successful antitumor effects. In this study, a combination therapy is designed based on phototactic, photosynthetic, and phototherapeutic Chlamydomonas Reinhardtii (CHL)-glycol chitosan (GCS)-polypyrrole (PPy) nanoparticle (NP)-enhanced immunity combined with the tumor microenvironment turnover of cytotoxic T cells and M1/M2 macrophages, which is based on photothermal GCS-PPy NPs decorated onto the phototactic and photosynthetic CHL. Phototherapy based on CHL-GCS-PPy NPs alleviates hypoxia and modulates the tumor immune microenvironment, which induces tumor cell death. In particular, the precise antitumor immune response and potent immune memory induced by combining self-navigated phototherapies significantly alleviate the progression of bladder cancer in C57BL/6 mice and effectively inhibit bladder tumor growth. Furthermore, they also potentially prevent tumor recurrence, which provides a promising therapeutic strategy for clinical tumor therapy.

Self-Produced O2 CNs-Based Nanocarriers of DNA Hydrophobization Strategy Triggers Photodynamic and Mitochondrial-Derived Ferroptosis for Hepatocellular Carcinoma Combined Treatment

Hypoxia can aggravate tumor occurrence, development, invasion, and metastasis, and greatly inhibit the photodynamic therapy (PDT) effect. Herein, carbon nitride (CNs)-based DNA and photosensitizer co-delivery systems (BPSCNs) with oxygen-producing functions are developed to address this problem. Selenide glucose (Seglu) is used as the dopant to prepare red/NIR-active CNs (SegluCNs). The tumor-targeting unit Bio-PEG2000 is utilized to construct BPSCNs nanoparticles through esterification reactions. Furthermore, DNA hydrophobization is realized via mixing P53 gene with a positively charged mitochondrial-targeted near-infrared (NIR) emitting photosensitizer (MTTPY), which is encapsulated in non-cationic BPSCNs for synergistic delivery. Ester bonds in BPSCNs@MTTPY-P53 complexes can be disrupted by lipase in the liver to facilitate P53 release, upregulated P53 expression, and promoted HIF-1α degradation in mitochondria. In addition, the oxygen produced by the complexes improved the hypoxic microenvironment of hepatocellular carcinoma (HCC), synergistically downregulated HIF-1α expression in mitochondria, promoted mitochondrial-derived ferroptosis and enhanced the PDT effect of the MTTPY unit. Both in vivo and in vitro experiments indicated that the transfected P53-DNA, produced O2 and ROS by these complexes synergistically led to mitochondrial-derived ferroptosis in hepatoma cells through the HIF-1α/SLC7A11 pathway, and completely avoiding PDT resistance caused by hypoxia, exerting a significant therapeutic role in HCC treatment.

Construction of nucleus-targeted photosensitizer and highly effective photodynamic immunotherapy for cancer

Nucleus is the largest and most important organelle within eukaryotic cells, containing most of the cell's genetic material, DNA. It serves as the central hub for genetic regulation and metabolism, making it an ideal target for subcellular drug delivery. The development of nucleus-targeted photosensitizers allows for the rapid and effective destruction of critical components such as DNA within the nucleus. This achieves the goal of efficiently eliminating cancer cells. However, most organic molecules, including photosensitizers, cannot penetrate the nuclear membrane, making the design and synthesis of nucleus-targeted photosensitizers both significant and challenging. The authors have designed and synthesized a nucleus-targeted activatable photosensitive probe (CMT-I). In vitro spectral analyses demonstrate that CMT-I is specifically activated by ct-DNA, significantly enhancing fluorescence-a 49-fold increase is observed upon binding. Furthermore, under 590 nm light irradiation, CMT-I effectively generates 1O2. Molecular docking show that CMT-I selectively binds to DNA through hydrogen bonds and ᴨ-ᴨ conjugation. RNA sequencing experiments reveal that photodynamic therapy activates immunity within tumor cells, triggering an adaptive immune response. In vivo therapeutic experiments further verify the enhanced anti-tumor immunity of CMT-I, which is crucial for effectively eliminating immunologically cold tumors and highlights the potential of DNA-targeted photodynamic therapy in precise cancer treatment.

Singlet oxygen storage and controlled release for improving photodynamic therapy against hypoxic tumor

Photodynamic therapy (PDT) is considered to be a promising tumor treatment method due to its non-invasiveness and low risk. However, there are two factors that affect the efficacy of this therapy. One is the light source and the other is the tumor hypoxia. An emerging PDT strategy has been developed to break these limits. This strategy is to adopt compounds, such as 2-pyridone, anthracene, and naphthalene derivatives, that have the ability to store and controlledly release the singlet oxygen (1O2) to achieve PDT in the dark. In this review, we focus on the construction strategies for integrated antitumor drugs containing these 1O2 storage/release units and photosensitizers and summarize their PDT performance in hypoxic tumors or in the dark. The methods to integrate these compounds with photosensitizers or nanocarriers are also discussed in detail to provide insightful design guidelines for the design of highly efficient antitumor systems based on 1O2 storage and controlled release.

Photodynamic therapy with NIR-II probes: review on state-of-the-art tools and strategies

In 2022 10% of the world's population was aged 65+, and by 2100 this segment is expected to hit 25%. These demographic changes place considerable pressure over healthcare systems worldwide, which results in an urgent need for accurate, inexpensive and non-invasive ways to treat cancers, a family of diseases correlated with age. Among the therapeutic tools that gained important attention in this context, photodynamic therapies (PDT), which use photosensitizers to produce cytotoxic substances for selectively destroying tumor cells and tissues under light irradiation, profile as important players for next-generation nanomedicine. However, the development of clinical applications is progressing at slow pace, due to still pending bottlenecks, such as the limited tissue penetration of the excitation light, and insufficient targeting performance of the therapeutic probes to fully avoid damage to normal cells and tissues. The penetration depth of long-wavelength near infrared (NIR) light is significantly higher than that of short-wavelength UV and visible light, and thus NIR light in the second window (NIR-II) is acknowledged as the preferred phototherapeutic means for eliminating deep-seated tumors, given the higher maximum permissible exposure, reduced phototoxicity and low autofluorescence, among others. Upon collective multidisciplinary efforts of experts in materials science, medicine and biology, multifunctional NIR-II inorganic or organic photosensitizers have been widely developed. This review overviews the current state-of-the art on NIR-II-activated photosensitizers and their applications for the treatment of deep tumors. We also place focus on recent efforts that combine NIR-II activated PDT with other complementary therapeutic routes such as photothermal therapy, chemotherapy, immunotherapy, starvation, and gas therapies. Finally, we discuss still pending challenges and problems of PDT and provide a series of perspectives that we find useful for further extending the state-of-the art on NIR-II-triggered PDT.

Recent progress of porphyrin metal-organic frameworks for combined photodynamic therapy and hypoxia-activated chemotherapy

Nanoscale metal-organic frameworks integrated with porphyrins (Por-nMOFs) have emerged as efficient nanoplatforms for photodynamic therapy (PDT), which relies on the conversion of molecular oxygen into cytotoxic singlet oxygen. However, the hypoxic microenvironment within tumors significantly limits the efficacy of PDT. To address this challenge, researchers have explored various strategies to either alter or exploit the hypoxic conditions in tumors. One such strategy involves leveraging the porous structure of Por-nMOFs to load hypoxia-activated prodrugs (HAPs) like tirapazamine (TPZ), thereby utilizing the tumor's intrinsic hypoxic environment to trigger a chemotherapeutic effect that synergizes with PDT. Advances in nanoscience have enabled the development of porphyrin-based nMOFs capable of simultaneously loading both porphyrin photosensitizers and TPZ, ensuring effective release within cancer cells under high-phosphate conditions. The subsequent activation of co-loaded TPZ, by the tumor's own hypoxic microenvironment, and that created during PDT, facilitates a combined PDT and chemotherapy approach. This method not only enhances the suppression of cancer cell proliferation but also improves control over tumor metastasis while mitigating the negative impact of hypoxia on singular Por-nMOFs in PDT. This review summarizes recent advances in Por-nMOFs research, focusing on the design strategies for enhancing water dispersibility, circulatory stability, and targeting specificity through post-synthetic modifications. Additionally, this review highlights the bioapplication of Por-nMOFs by integrating TPZ chemotherapy and other therapeutic modalities to combat hypoxic and metastatic malignancies. We anticipate that this review will inspire further research into Por-nMOFs and advance their application in biomedicine.

Substituent-Modulated Excited Triplet States and Activities of Ruthenium Complexes for Dual Photodynamic/Sonodynamic Therapy to Cisplatin-Resistant Non-Small Cell Lung Cancer

Six polypyridyl Ru(II) complexes were designed for single-molecule photodynamic and sonodynamic therapy (PDT/SDT) synergistic multimodal anticancer toward cisplatin-resistant NSCLC. They demonstrated lowest 3ES with distinct intraligand transition nature, which is beneficial for singlet oxygen generation. Remarkable quantum yields of both singlet oxygen and superoxide anion under either 808 nm laser irradiation or ultrasonic treatment and could induce apoptosis and ferroptosis of A549R cells. Cytotoxicity experiments clearly demonstrated a synergistic effect between PDT and SDT. The relationship between the structures of these complexes and their cellular biological mechanisms has been explored in detail. Using a single-molecule sensitizer to achieve synergistic PDT/SDT may provide valuable insights for the treatment of drug-resistant tumors that located deeply and in hypoxic microenvironment.

Multimodal Photodynamic Therapy by Inhibiting the Nrf2/ARE Signaling Pathway in Tumors

Photodynamic therapy (PDT) has been widely used in the clinical therapy of various tumors, especially superficial tumors. However, the tumor microenvironment presents hypoxia, as well as the inherent antioxidant system (e.g., Nrf2) of tumor cells limits the therapeutic outcomes. Herein, a cascade-responsive "oxidative stress amplifier" (named EZ@TD) is designed by encapsulating manganese-doped carbon dots acting as a photosensitizer and catalase (CAT)-like nanozyme within pH-sensitive ZIF-8 and Zn2+-activated DNAzyme for relieving hypoxia and efficient Nrf2 gene disruption to enhance PDT. It is demonstrated that EZ@TD synergistically inhibited tumor growth and activated the antitumor immune response by inhibiting the Nrf2/ARE signaling pathway in tumors. We provide a new paradigm for amplifying intracellular oxidative stress by interfering with various signaling pathways.

Anthracene-Based Endoperoxides as Self-Sensitized Singlet Oxygen Carriers for Hypoxic-Tumor Photodynamic Therapy

Singlet oxygen is a crucial reactive oxygen species (ROS) in photodynamic therapy (PDT). However, the hypoxic tumor microenvironment limits the production of cytotoxic singlet oxygen through the light irradiation of PDT photosensitizers (PSs). This restriction poses a major challenge in improving the effectiveness of PDT. To overcome this challenge, researchers have explored the development of singlet oxygen carriers that can capture and release singlet oxygen in physiological conditions. Among these developments, anthracene-based endoperoxides, initially discovered almost 100 years ago, have shown the ability to generate singlet oxygen controllably under thermal or photo stimuli. Recent advancements have led to the development of a new class of self-sensitized anthracene-endoperoxides, with potential applications in enhancing PDT effects for hypoxic tumors. This review discusses the current research progress in utilizing self-sensitized anthracene-endoperoxides as singlet oxygen carriers for improved PDT. It covers anthracene-conjugated small organic molecules, metal-organic complexes, polymeric structures, and other self-sensitized nano-structures. The molecular structural designs, mechanisms, and characteristics of these systems will be discussed. This review aims to provide valuable insights for developing high-performance singlet oxygen carriers for hypoxic-tumor PDT.

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

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

Multifunctional hyaluronic acid ligand-assisted construction of CD44- and mitochondria-targeted self-assembled upconversion nanoparticles for enhanced photodynamic therapy

Upconversion nanoparticles (UCNPs) have been used as a potential nanocarrier for photosensitizers (PSs), which have demonstrated a great deal of promise in achieving an effective photodynamic therapy (PDT) for deep-seated tumors. However, overcoming biological barriers to achieve mitochondria-targeted PDT remains a major challenge. Herein, CD44- and mitochondria-targeted photodynamic nanosystems were fabricated through the self-assembly of hyaluronic acid-conjugated-methoxy poly(ethylene glycol)-diethylenetriamine-grafted-(chlorin e6-dihydrolipoic acid-(3-carboxypropyl)triphenylphosphine bromide) polymeric ligands (HA-c-mPEG-Deta-g-(Ce6-DHLA-TPP)) and NaErF4:Tm@NaYF4 core-shell UCNPs (termed CMPNs). The CMPNs presented ideal physiological stability, a good drug loading capacity and an improved capacity for the generation of singlet oxygen (1O2) based on the FRET mechanism. Significantly, confocal images revealed that CMPNs not only facilitated cellular uptake through CD44-receptor-targeted endocytosis, subsequently enabling rapid evasion from endo-lysosomal sequestration, but also specifically targeted mitochondria, ultimately inducing a profound disruption of mitochondrial membrane potential, which triggered apoptosis upon laser irradiation, thereby significantly enhancing the therapeutic effect. Furthermore, in vitro antitumor experiments further confirmed the substantial enhancement in cancer cell killing efficiency achieved by treating with CMPNs upon near-infrared (NIR) laser irradiation. This innovative approach holds promise for the development of NIR-laser-activated photodynamic nanoagents specifically designed for mitochondria-targeted PDT, thus addressing the limitations of the current PDT treatments.

A Spatiotemporally Controlled Gene-Regulation Strategy for Combined Tumor Therapy Based on Upconversion Hybrid Nanosystem

The lack of precise spatiotemporal gene modulation and therapy impedes progress in medical applications. Herein, a 980 nm near-infrared (NIR) light-controlled nanoplatform, namely URMT, is developed, which can allow spatiotemporally controlled photodynamic therapy and trigger the enzyme-activated gene expression regulation in tumors. URMT is constructed by engineering an enzyme-activatable antisense oligonucleotide, which combined with an upconversion nanoparticle (UCNP)-based photodynamic nanosystem, followed by the surface functionalization of triphenylphosphine (TPP), a mitochondria-targeting ligand. URMT allows for the 980 nm NIR light-activated generation of reactive oxygen species, which can induce the translocation of a DNA repair enzyme (namely apurinic/apyrimidinic endonuclease 1, APE1) from the nucleus to mitochondria. APE1 can recognize the basic apurinic/apyrimidinic (AP) sites in DNA double-strands and perform cleavage, thereby releasing the functional single-strands for gene regulation. Overall, an augmented antitumor effect is observed due to NIR light-controlled mitochondrial damage and enzyme-activated gene regulation. Altogether, the approach reported in this study offers high spatiotemporal precision and shows the potential to achieve precise and specific gene regulation for targeted tumor treatment.

Long-wavelength triggered iridium(III) complex nanoparticles for photodynamic therapy against hypoxic cancer

A long-wavelength triggered cationic iridium(III) complex, Ir5, and its corresponding nanoparticles with the ability to generate type I and type II reactive oxygen species have been synthesised. The complex targets mitochondria and achieves an excellent photodynamic therapy effect in hypoxic cancer cells.

Recent developments in two-dimensional molybdenum disulfide-based multimodal cancer theranostics

Recent advancements in cancer research have led to the generation of innovative nanomaterials for improved diagnostic and therapeutic strategies. Despite the proven potential of two-dimensional (2D) molybdenum disulfide (MoS2) as a versatile platform in biomedical applications, few review articles have focused on MoS2-based platforms for cancer theranostics. This review aims to fill this gap by providing a comprehensive overview of the latest developments in 2D MoS2 cancer theranostics and emerging strategies in this field. This review highlights the potential applications of 2D MoS2 in single-model imaging and therapy, including fluorescence imaging, photoacoustic imaging, photothermal therapy, and catalytic therapy. This review further classifies the potential of 2D MoS2 in multimodal imaging for diagnostic and synergistic theranostic platforms. In particular, this review underscores the progress of 2D MoS2 as an integrated drug delivery system, covering a broad spectrum of therapeutic strategies from chemotherapy and gene therapy to immunotherapy and photodynamic therapy. Finally, this review discusses the current challenges and future perspectives in meeting the diverse demands of advanced cancer diagnostic and theranostic applications.

Research progress of sorafenib drug delivery system in the treatment of hepatocellular carcinoma: An update

Hepatocellular carcinoma (HCC) is one of the most prevalent malignant tumors in the contemporary era, representing a significant global health concern. Early HCC patients have mild symptoms or are asymptomatic, which promotes the onset and progression of the disease. Moreover, advanced HCC is insensitive to chemotherapy, making traditional clinical treatment unable to block cancer development. Sorafenib (SFB) is a first-line targeted drug for advanced HCC patients with anti-angiogenesis and anti-tumor cell proliferation effects. However, the efficacy of SFB is constrained by its off-target distribution, rapid metabolism, and multi-drug resistance. In recent years, nanoparticles based on a variety of materials have been demonstrated to enhance the targeting and therapeutic efficacy of SFB against HCC. Concurrently, the advent of joint drug delivery systems has furnished crucial empirical evidence for reversing SFB resistance. This review will summarize the application of nanotechnology in the field of HCC treatment over the past five years. It will focus on the research progress of SFB delivery systems combined with multiple therapeutic modalities in HCC treatment.

Aggregation-Induced Emission CN-Based Nanoparticles to Alleviate Hypoxic Liver Fibrosis via Triggering HSC Ferroptosis and Enhancing Photodynamic Therapy

Hypoxia can lead to liver fibrosis and severely limits the efficacy of photodynamic therapy (PDT). Herein, carbon nitride (CN)-based hybrid nanoparticles (NPs) VPSGCNs@TSI for light-driven water splitting were utilized to solve this problem. CNs were doped with selenide glucose (Se-glu) to enhance their red/NIR region absorption. Then, vitamin A-poly(ethylene glycol) (VA-PEG) fragments and aggregation-induced emission (AIE) photosensitizers TSI were introduced into Se-glu-doped CN NPs (VPSGCNs) to construct VPSGCNs@TSI NPs. The introduction of VA-PEG fragments enhanced the targeting of the NPs to activated hepatic stellate cells (HSCs) and reduced their toxicity to ordinary liver cells. VPSGCN units could trigger water splitting to generate O2 under 660 nm laser irradiation, improve the hypoxic environment of the fibrosis site, downregulate HIF-1α expression, and activate HSC ferroptosis via the HIF-1α/SLC7A11 pathway. In addition, generated O2 could also increase the reactive oxygen species (ROS) production of TSI units in a hypoxic environment, thereby completely reversing hypoxia-triggered PDT resistance to enhance the PDT effect. The combination of water-splitting materials and photodynamic materials showed a 1 + 1 > 2 effect in increasing oxygen levels in liver fibrosis, promoting ferroptosis of activated HSCs and reversing PDT resistance caused by hypoxia.

Bithiophene-Functionalized Infrared Two-Photon Absorption Metal Complexes as Single-Molecule Platforms for Synergistic Photodynamic, Photothermal, and Chemotherapy

A planar conjugated ligand functionalized with bithiophene and its Ru(II), Os(II), and Ir(III) complexes have been constructed as single-molecule platform for synergistic photodynamic, photothermal, and chemotherapy. The complexes have significant two-photon absorption at 808 nm and remarkable singlet oxygen and superoxide anion production in aqueous solution and cells when exposed to 808 nm infrared irradiation. The most potent Ru(II) complex Ru7 enters tumor cells via the rare macropinocytosis, locates in both nuclei and mitochondria, and regulates DNA-related chemotherapeutic mechanisms intranuclearly including DNA topoisomerase and RNA polymerase inhibition and their synergistic effects with photoactivated apoptosis, ferroptosis and DNA cleavage. Ru7 exhibits high efficacy in vivo for malignant melanoma and cisplatin-resistant non-small cell lung cancer tumors, with a 100 % survival rate of mice, low toxicity to normal cells and low residual rate. Such an infrared two-photon activatable metal complex may contribute to a new generation of single-molecule-based integrated diagnosis and treatment platform to address drug resistance in clinical practice and phototherapy for large, deeply located solid tumors.

Metal-Organic Framework PCN-224 Combined Cobalt Oxide Nanoparticles for Hypoxia Relief and Synergistic Photodynamic/Chemodynamic Therapy

Photodynamic therapy (PDT) and chemodynamic therapy (CDT) are promising tumor treatments mediated by reactive oxygen species (ROS), which have the advantages of being minimally invasive. However, the hypoxia of tumor microenvironment and poor target ability often reduce the therapeutic effect. Here we propose a tumor targeted nanoplatform PCN-224@Co3O4-HA for enhanced PDT and synergistic CDT, constructed by hyaluronate-modified Co3O4 nanoparticles decorated metal-organic framework PCN-224. Co3O4 can catalyze the decomposition of highly expressed H2O2 in tumor cells to produce oxygen and alleviate the problem of hypoxia. It can also produce hydroxyl radicals according to the Fenton-like reaction for chemical dynamic therapy, significantly improving the therapeutic effect. The cell survival experiment showed that after in vitro treatment, 4T1 and MCF-7 cancer cells died in a large area under the anaerobic state, while the survival ability of normal cell L02 was nearly unchanged. This result effectively indicated that PCN-224@Co3O4-HA could effectively relieve tumor hypoxia and improve the effect of PDT and synergistic CDT. Cell uptake experiments showed that PCN-224@Co3O4-HA had good targeting properties and could effectively aggregate in tumor cells. In vivo experiments on mice, PCN-224@Co3O4-HA presented reliable biosafety performance, and can cooperate with PDT and CDT therapy to prevent the growth of tumor.

Unveiling innovative therapeutic strategies and future trajectories on stimuli-responsive drug delivery systems for targeted treatment of breast carcinoma

This comprehensive review delineates the latest advancements in stimuli-responsive drug delivery systems engineered for the targeted treatment of breast carcinoma. The manuscript commences by introducing mammary carcinoma and the current therapeutic methodologies, underscoring the urgency for innovative therapeutic strategies. Subsequently, it elucidates the logic behind the employment of stimuli-responsive drug delivery systems, which promise targeted drug administration and the minimization of adverse reactions. The review proffers an in-depth analysis of diverse types of stimuli-responsive systems, including thermoresponsive, pH-responsive, and enzyme-responsive nanocarriers. The paramount importance of material choice, biocompatibility, and drug loading strategies in the design of these systems is accentuated. The review explores characterization methodologies for stimuli-responsive nanocarriers and probes preclinical evaluations of their efficacy, toxicity, pharmacokinetics, and biodistribution in mammary carcinoma models. Clinical applications of stimuli-responsive systems, ongoing clinical trials, the potential of combination therapies, and the utility of multifunctional nanocarriers for the co-delivery of assorted drugs and therapies are also discussed. The manuscript addresses the persistent challenge of drug resistance in mammary carcinoma and the potential of stimuli-responsive systems in surmounting it. Regulatory and safety considerations, including FDA guidelines and biocompatibility assessments, are outlined. The review concludes by spotlighting future trajectories and emergent technologies in stimuli-responsive drug delivery, focusing on pioneering approaches, advancements in nanotechnology, and personalized medicine considerations. This review aims to serve as a valuable compendium for researchers and clinicians interested in the development of efficacious and safe stimuli-responsive drug delivery systems for the treatment of breast carcinoma.

Natural-product-based, carrier-free, noncovalent nanoparticles for tumor chemo-photodynamic combination therapy

Cancer, with its diversity, heterogeneity, and complexity, is a significant contributor to global morbidity, disability, and mortality, highlighting the necessity for transformative treatment approaches. Photodynamic therapy (PDT) has aroused continuous interest as a viable alternative to conventional cancer treatments that encounter drug resistance. Nanotechnology has brought new advances in medicine and has shown great potential in drug delivery and cancer treatment. For precise and efficient therapeutic utilization of such a tumor therapeutic approach with high spatiotemporal selectivity and minimal invasiveness, the carrier-free noncovalent nanoparticles (NPs) based on chemo-photodynamic combination therapy is essential. Utilizing natural products as the foundation for nanodrug development offers unparalleled advantages, including exceptional pharmacological activity, easy functionalization/modification, and well biocompatibility. The natural-product-based, carrier-free, noncovalent NPs revealed excellent synergistic anticancer activity in comparison with free photosensitizers and free bioactive natural products, representing an alternative and favorable combination therapeutic avenue to improve therapeutic efficacy. Herein, a comprehensive summary of current strategies and representative application examples of carrier-free noncovalent NPs in the past decade based on natural products (such as paclitaxel, 10-hydroxycamptothecin, doxorubicin, etoposide, combretastatin A4, epigallocatechin gallate, and curcumin) for tumor chemo-photodynamic combination therapy. We highlight the insightful design and synthesis of the smart carrier-free NPs that aim to enhance PDT efficacy. Meanwhile, we discuss the future challenges and potential opportunities associated with these NPs to provide new enlightenment, spur innovative ideas, and facilitate PDT-mediated clinical transformation.

Photodynamic anticancer activity evaluation of novel 5-aminolevulinic acid and 3-hydroxypyridinone conjugates

5-Aminolevulinic acid (ALA) and its derivatives, serving as the endogenous precursor of the photosensitizer (PS) protoporphyrin IX (PpIX), successfully applied in tumor imaging and photodynamic therapy (PDT). ALA and its derivatives have been used to treat actinic keratosis (AK), basal cell carcinoma (BCC), and improve the detection of superficial bladder cancer. However, the high hydrophilicity of ALA and the conversion of PpIX to heme have limited the accumulation of PpIX, hindering the efficiency and potential application of ALA-PDT. This study aims to evaluate the PDT activity of three rationally designed series of ALA-HPO prodrugs, which were based on enhancing the lipophilicity of the prodrugs and reducing the labile iron pool (LIP) through HPO iron chelators to promote PpIX accumulation. Twenty-four ALA-HPO conjugates, incorporating amide, amino acid, and ester linkages, were synthesized. Most of the conjugates, exhibited no dark-toxicity to cells, according to bioactivity evaluation. Ester conjugates 19a-g showed promoted phototoxicity when tested on tumor cell lines, and this increased phototoxicity was strongly correlated with elevated PpIX levels. Among them, conjugate 19c emerged as the most promising (HeLa, IC50 = 24.25 ± 1.43 μM; MCF-7, IC50 = 43.30 ± 1.76 μM; A375, IC50 = 28.03 ± 1.00 μM), displaying superior photodynamic anticancer activity to ALA (IC50 > 100 μM). At a concentration of 80 μM, the fluorescence intensity of PpIX induced by compound 19c in HeLa, MCF-7, and A375 cells was 18.9, 5.3, and 2.8 times higher, respectively, than that induced by ALA. In conclusion, cellular phototoxicity showed a strong correlation with intracellular PpIX fluorescence levels, indicating the potential application of ALA-HPO conjugates in ALA-PDT.

Hypoxia-Activated Theragnostic Prodrugs (HATPs): Current State and Future Perspectives

Hypoxia is a significant feature of solid tumors and frequently poses a challenge to the effectiveness of tumor-targeted chemotherapeutics, thereby limiting their anticancer activity. Hypoxia-activated prodrugs represent a class of bio-reductive agents that can be selectively activated in hypoxic compartments to unleash the toxic warhead and thus, eliminate malignant tumor cells. However, their applicability can be further elevated by installing fluorescent modalities to yield hypoxia-activated theragnostic prodrugs (HATPs), which can be utilized for the simultaneous visualization and treatment of hypoxic tumor cells. The scope of this review is to summarize noteworthy advances in recent HATPs, highlight the challenges and opportunities for their further development, and discuss their potency to serve as personalized medicines in the future.

A multi-functional nano-platform based on LiGa4.99O8:Cr0.01/IrO2 with near infrared-persistent luminescence, "afterglow" photodynamic and photo-thermal functions

Multi-functionalised nano-platforms based on persistent-luminescence nanoparticles (PLNPs) have attracted considerable attention for biomedical applications owing to their lack of background noise and suitability for in vivo imaging without the need for in situ excitation. However, nano-platforms based on PLNPs for continuous photodynamic therapy (PDT) are currently lacking. Herein, we report a nano-platform (LiGa4.99O8:Cr0.01/IrO2, LGO:Cr/IrO2) prepared using PLNPs (LiGa4.99O8:Cr0.01, LGO:Cr) covalently bonded with iridium oxide nanoparticles (IrO2 NPs), producing near-infrared (NIR) persistent luminescence, "afterglow" PDT and photo-thermal therapy (PTT) effects. The LGO:Cr/IrO2 not only exhibits NIR-persistent luminescence at 719 nm and a PTT effect under 808 nm irradiation but also a continuous "afterglow" PDT effect without the need for in situ excitation owing to persistent energy transfer from LGO:Cr to the IrO2 NPs, in turn generating reactive oxygen species (ROS). This multi-functional nano-platform is expected to further promote the application of PLNPs in tumour treatment.

Cascade-Catalyzed Nanogel for Amplifying Starvation Therapy by Nitric Oxide-Mediated Hypoxia Alleviation

Glucose oxidase (Gox)-mediated starvation therapy offers a prospective advantage for malignancy treatment by interrupting the glucose supply to neoplastic cells. However, the negative charge of the Gox surface hinders its enrichment in tumor tissues. Furthermore, Gox-mediated starvation therapy infiltrates large amounts of hydrogen peroxide (H2O2) to surround normal tissues and exacerbate intracellular hypoxia. In this study, a cascade-catalyzed nanogel (A-NE) was developed to boost the antitumor effects of starvation therapy by glucose consumption and cascade reactive release of nitric oxide (NO) to relieve hypoxia. First, the surface cross-linking structure of A-NE can serve as a bioimmobilization for Gox, ensuring Gox stability while improving the encapsulation efficiency. Then, Gox-mediated starvation therapy efficiently inhibited the proliferation of tumor cells while generating large amounts of H2O2. In addition, covalent l-arginine (l-Arg) in A-NE consumed H2O2 derived from glucose decomposition to generate NO, which augmented starvation therapy on metastatic tumors by alleviating tumor hypoxia. Eventually, both in vivo and in vitro studies indicated that nanogels remarkably inhibited in situ tumor growth and hindered metastatic tumor recurrence, offering an alternative possibility for clinical intervention.

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

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

Advances in Nanodynamic Therapy for Cancer Treatment

Nanodynamic therapy (NDT) exerts its anti-tumor effect by activating nanosensitizers to generate large amounts of reactive oxygen species (ROS) in tumor cells. NDT enhances tumor-specific targeting and selectivity by leveraging the tumor microenvironment (TME) and mechanisms that boost anti-tumor immune responses. It also minimizes damage to surrounding healthy tissues and enhances cytotoxicity in tumor cells, showing promise in cancer treatment, with significant potential. This review covers the research progress in five major nanodynamic therapies: photodynamic therapy (PDT), electrodynamic therapy (EDT), sonodynamic therapy (SDT), radiodynamic therapy (RDT), and chemodynamic therapy (CDT), emphasizing the significant role of advanced nanotechnology in the development of NDT for anti-tumor purposes. The mechanisms, effects, and challenges faced by these NDTs are discussed, along with their respective solutions for enhancing anti-tumor efficacy, such as pH response, oxygen delivery, and combined immunotherapy. Finally, this review briefly addresses challenges in the clinical translation of NDT.

Nanoparticles as carriers of photosensitizers to improve photodynamic therapy in cancer

Photodynamic therapy (PDT) has emerged as a promising non invasive therapeutic approach for cancer treatment, offering unique advantages over conventional treatments. The combination of light activation and photosensitizing agents allows for targeted and localized destruction of cancer cells, reducing damage to surrounding healthy tissues. In recent years, the integration of nanoparticles with PDT has garnered significant attention due to their potential to enhance therapeutic outcomes. This review article aims to provide a comprehensive overview of the current state-of-the-art in utilizing nanoparticles for photodynamic therapy in cancer treatment. We summarized various nanoparticle-based approaches, their properties, and their implications in optimizing PDT efficacy, and discussed challenges and prospects in the field.

Effects of Photodynamic Therapy on Tumor Metabolism and Oxygenation Revealed by Fluorescence and Phosphorescence Lifetime Imaging

This work was aimed at the complex analysis of the metabolic and oxygen statuses of tumors in vivo after photodynamic therapy (PDT). Studies were conducted on mouse tumor model using two types of photosensitizers-chlorin e6-based drug Photoditazine predominantly targeted to the vasculature and genetically encoded photosensitizer KillerRed targeted to the chromatin. Metabolism of tumor cells was assessed by the fluorescence lifetime of the metabolic redox-cofactor NAD(P)H, using fluorescence lifetime imaging. Oxygen content was assessed using phosphorescence lifetime macro-imaging with an oxygen-sensitive probe. For visualization of the perfused microvasculature, an optical coherence tomography-based angiography was used. It was found that PDT induces different alterations in cellular metabolism, depending on the degree of oxygen depletion. Moderate decrease in oxygen in the case of KillerRed was accompanied by an increase in the fraction of free NAD(P)H, an indicator of glycolytic switch, early after the treatment. Severe hypoxia after PDT with Photoditazine resulted from a vascular shutdown yielded in a persistent increase in protein-bound (mitochondrial) fraction of NAD(P)H. These findings improve our understanding of physiological mechanisms of PDT in cellular and vascular modes and can be useful to develop new approaches to monitoring its efficacy.

Mitochondrial-Targeting Nanotrapper Captured Copper Ions to Alleviate Tumor Hypoxia for Amplified Photoimmunotherapy in Breast Cancer

Hypoxia is a pervasive feature of solid tumors, which significantly limits the therapeutic effect of photodynamic therapy (PDT) and further influences the immunotherapy efficiency in breast cancer. However, the transient alleviation of tumor hypoxia fails to address the underlying issue of increased oxygen consumption, resulting from the rapid proliferation of tumor cells. At present, studies have found that the reduction of the oxygen consumption rate (OCR) by cytochrome C oxidase (COX) inhibition that induced oxidative phosphorylation (OXHPOS) suppression was able to solve the proposed problem. Herein, we developed a specific mitochondrial-targeting nanotrapper (I@MSN-Im-PEG), which exhibited good copper chelating ability to inhibit COX for reducing the OCR. The results proved that the nanotrapper significantly alleviated the hypoxic tumor microenvironment by copper chelation in mitochondria and enhanced the PDT effect in vitro and in vivo. Meanwhile, the nanotrapper improved photoimmunotherapy through both enhancing PDT-induced immunogenetic cell death (ICD) effects and reversing Treg-mediated immune suppression on 4T1 tumor-bearing mice. The mitochondrial-targeting nanotrapper provided a novel and efficacious strategy to enhance the PDT effect and amplify photoimmunotherapy in breast cancer.

Current Advances in Photodynamic Therapy (PDT) and the Future Potential of PDT-Combinatorial Cancer Therapies

Photodynamic therapy (PDT) is a two-stage treatment that implies the use of light energy, oxygen, and light-activated compounds (photosensitizers) to elicit cancerous and precancerous cell death after light activation (phototoxicity). The biophysical, bioengineering aspects and its combinations with other strategies are highlighted in this review, both conceptually and as they are currently applied clinically. We further explore the recent advancements of PDT with the use of nanotechnology, including quantum dots as innovative photosensitizers or energy donors as well as the combination of PDT with radiotherapy and immunotherapy as future promising cancer treatments. Finally, we emphasize the potential significance of organoids as physiologically relevant models for PDT.

Hypoxia and Singlet Oxygen Dual-Responsive Micelles for Photodynamic and Chemotherapy Therapy Featured with Enhanced Cellular Uptake and Triggered Cargo Delivery

Introduction

Combination therapy provides better outcomes than a single therapy and becomes an efficient strategy for cancer treatment. In this study, we designed a hypoxia- and singlet oxygen-responsive polymeric micelles which contain azo and nitroimidazole groups for enhanced cellular uptake, repaid cargo release, and codelivery of photosensitizer Ce6 and hypoxia-activated prodrug tirapazamine TPZ (DHM-Ce6@TPZ), which could be used for combining Ce6-mediated photodynamic therapy (PDT) and PDT-activated chemotherapy to enhance the therapy effect of cancer.

Methods

The hypoxia- and singlet oxygen-responsive polymeric micelles DHM-Ce6@TPZ were prepared by film hydration method. The morphology, physicochemical properties, stimuli responsiveness, in vitro singlet oxygen production, cellular uptake, and cell viability were evaluated. In addition, the in vivo therapeutic effects of the micelles were verified using a tumor xenograft mice model.

Results

The resulting dual-responsive micelles not only increased the concentration of intracellular photosensitizer and TPZ, but also facilitated photosensitizer and TPZ release for enhanced integration of photodynamic and chemotherapy therapy. As a photosensitizer, Ce6 induced PDT by generating toxic singlet reactive oxygen species (ROS), resulting in a hypoxic tumor environment to activate the prodrug TPZ to achieve efficient chemotherapy, thereby evoking a synergistic photodynamic and chemotherapy therapeutic effect. The cascade synergistic therapeutic effect of DHM-Ce6@TPZ was effectively evaluated both in vitro and in vivo to inhibit tumor growth in a breast cancer mice model.

Conclusion

The designed multifunctional micellar nano platform could be a convenient and powerful vehicle for the efficient co-delivery of photosensitizers and chemical drugs for enhanced synergistic photodynamic and chemotherapy therapeutic effect of cancer.

NIR-II Photoacoustic Imaging-Guided Oxygen Delivery and Controlled Release Improves Photodynamic Therapy for Hepatocellular Carcinoma

Hypoxia, a prominent hallmark of hepatocellular carcinoma (HCC), undermines curative outcomes, elevates recurrence rates, and fosters metastasis, particularly during photodynamic therapy (PDT) in clinical settings. Studies indicate that alleviating tumor hypoxia enhances PDT efficacy. However, persistent challenges, including suboptimal oxygen delivery efficiency and absence of real-time feedback on blood oxygen fluctuations during PDT, considerably impede therapeutic efficacy in tumor treatment. This study addresses these issues using near-infrared-II (NIR-II) photoacoustic (PA) imaging for tumor-targeted oxygen delivery and controlled release. For this purpose, a biomimetic oxygen delivery system designated BLICP@O2 is developed, which utilizes hybrid tumor cell membranes and thermosensitive liposomes as oxygen carriers, incorporating the NIR-II dye IR1048, photosensitizer chlorin e6 (Ce6), and perfluorohexane. Upon sequential irradiation at 1064 and 690 nm, BLICP@O2 exhibits significant photothermal and photodynamic effects. Photothermal heating triggers oxygen release, enhancing the photodynamic effect of Ce6. Blood oxygen changes during PDT are tracked by multispectral PA imaging. Enhanced PDT efficacy, mediated by hypoxia relief, is convincingly demonstrated both in vitro and in vivo. This work presents an imaging-guided, dual-wavelength programmed cascaded treatment strategy for tumor-targeted oxygen delivery and controlled release, with real-time efficacy monitoring using PA imaging, offering valuable insights for overcoming challenges in PDT-based cancer therapy.

Imaging-Guided Photoacoustic Immunotherapy Based on the Polydopamine-Functionalized Black Phosphorus Nanocomposites

Phototherapy has great application prospects in superficial tumors, such as melanoma, esophageal cancer, and breast carcinoma, owing to the advantages of noninvasiveness, high spatiotemporal selectivity, and less side effects. However, classical phototherapies including photodynamic and photothermal therapy still need to settle the bottleneck problems of poor efficacy, inevitable thermal damage, and a high rate of postoperative recurrence. In this study, we developed a nanocomposite with excellent optical properties and immune-stimulating properties, termed PBP@CpG, which was obtained by functionalizing black phosphorus (BP) with polydopamine and further adsorbing CpG. Benefiting from the protection of polydopamine against BP, ideal light absorption, and photoacoustic conversion properties, PBP@CpG not only enables precisely delineation of the tumor region with photoacoustic imaging but also powerfully disrupts the plasma membrane and cytoskeleton of tumor cells with a photoacoustic cavitation effect. In addition, we found that the photoacoustic cavitation effect was also capable of inducing immunogenic cell death and remarkably strengthening the antitumor immune response upon cooperating with immune adjuvant CpG. Therefore, PBP@CpG was expected to provide a promising nanoplatform for optical theranostics and herald a new strategy of photoimmunotherapy based on the photoacoustic cavitation effects and immunostimulatory effect.

PDT-Induced Activation Enhanced by Hormone Response to Treatment

Photodynamic therapy (PDT) is a medical treatment with the use of a photosensitizing agent (PS), which, when activated by light, results in selective tissue damage with a cytotoxic effect on tumor cells. PDT leads to the induction of an acute-phase response, which results in the involvement of adrenal glucocorticoid (GC) hormones. PDT, by activating the hormonal response, affects the treatment of cancer. GC release is observed due to adrenal activity, which is driven by changes in the hypothalamic pituitary-adrenal axis triggered by stress signals emanating from the PDT treated tumor. The hormones released in this process in the context of the PDT-induced acute-phase response perform many important functions during anticancer therapy. They lead, among other things, to the systemic mobilization of neutrophils and the production of acute-phase reagents, and also control the production of immunoregulatory proteins and proteins that modulate inflammation. GCs can radically affect the activity of various inflammatory and immune cells, including the apoptosis of cancer cells. A better understanding of the modulation of GC activity could improve the outcomes of cancer patients treated with PDT.