Aggressive Man-Made Red Blood Cells for Hypoxia-Resistant Photodynamic Therapy

Ultrasound-Activated Theranostic Materials and Their Bioapplications

Ultrasound (US) is a promising external excitation modality for bioapplications, offering significant advantages over X-rays or lasers due to its low cost, high biosafety, and ideal tissue penetration depth. US-activated theranostic materials, comprising organic, inorganic, and hybrid-based compounds, hold particular value in synergistic cancer therapeutic and diagnostic applications. These materials exhibit excellent imaging properties, high drug delivery and release efficiency, and enhanced reactive oxygen species (ROS) production, making them suitable for clinical diagnostic imaging and therapeutic interventions. This review summarizes recent research on the design, performance, and optimization of US-mediated molecules/nanosystems for a wide range of biomedical applications. Additionally, the multifunctional use of these sonosensitizers in imaging, drug delivery, and sonodynamic therapy, especially in combination with other treatments, could pave the way for innovative strategies in disease therapy. Finally, an overview of this field's challenges and potential future directions is provided, highlighting pathways to promote clinical translation and application.

Gene-engineered polypeptide hydrogels with on-demand oxygenation and ECM-cell interaction mimicry for diabetic wound healing

The treatment of infected diabetic wounds remains a significant clinical challenge due to pathogen infection, excessive inflammation, and impaired angiogenesis with troubled extracellular matrix (ECM) - cell and cell - cell interaction. Herein, we prepared a Janus polypeptide-engineered hydrogel with programmable function driven by self-assembly of the same A domain. The hydrogel was composed of a V8-degradable AC10A layer loaded with hybrid phages (ABC) for precise bacterial inhibition and a PC10ARGD layer loaded with Mn-based mineralized erythrocyte (PEM) for continuous supply oxygen on demand. The results of laser speckle contrast imaging, photoacoustic imaging, and hyperspectral imaging demonstrated that the AC10A@BP-Ce6/PC10AR@EM hydrogel (ABC/PEM) accelerated the reconstruction of normal skin structure by breaking the oxygen diffusion barrier and supplying oxygen on demand to promote angiogenesis and functionalization. In addition, in vitro and in vivo experiment results showed that the ABC/PEM hydrogel can mimic positive ECM - cell interaction to inhibit the polarization of macrophage towards M1-type to slow down the inflammatory process by down-regulated yes-associated protein (YAP), and relieve the mechanical tension of fibroblasts and keratinocytes. Finally, the ABC/PEM hydrogel promotes a healing rate of 98.83 % on day 21 and results in the number of dermal appendages being eight times that of the negative group. This work presents an effective strategy for diabetes-related chronic infected wound management.

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.

Oxygen/siRNA-carrying fluoro-nanosensitizers for radio-immunotherapy sensitization

The anti-tumor efficacy of radiotherapy (RT) is limited by the hypoxic and immunosuppressive tumor microenvironment (TME), which leads to RT resistance and failure in eradicating distant metastatic lesions. Herein, we developed a fluorinated nanosensitizer that could deliver both oxygen (O2) and ADAR1 siRNA into tumor cells to reinforce RT by alleviating hypoxia and immunosuppression. Fluorinated poly(β-amino ester) (fPBAE) was designed to complex ADAR1 siRNA (siADAR1) via electrostatic attraction and load O2 due to the O2-dissolving capacity of fluoroalkyls. The formed nanocomplexes (NCs) facilitated robust cytosolic delivery into cancer cells after intratumoral injection, enabling efficient ADAR1 silencing to promote IFN-β release and enhance DC maturation and T cell infiltration. At the meantime, O2 was released to alleviate tumoral hypoxia. As thus, NCs significantly enhanced the anti-tumor efficacy of RT and when further coupled with programmed death ligand-1 antibody, they effectively restrained the growth of both treated primary tumors and untreated distant tumors by eliciting robust systemic immune response. This study therefore reports an enlightened strategy for remodeling the immunosuppressive TME and sensitizing radio-immunotherapy. STATEMENT OF SIGNIFICANCE: The hypoxic and immunosuppressive tumor microenvironment (TME) greatly limits the anti-tumor efficacy of radiotherapy (RT). To address this critical issue, a nano-sensitizer based on fluorinated poly(β-amino ester) (fPBAE) is herein developed to mediate efficient co-delivery of oxygen (O₂) and ADAR1 siRNA into tumor cells. ADAR1 silencing promotes DC maturation and T cell infiltration to reverse immunosuppression while the released O₂ alleviates hypoxia to sensitize RT. Thus, the nano-sensitizer remarkably enhances the anti-tumor efficacy of RT and elicits robust systemic immune response to eradicate primary and distant tumors when further coupled with PD-L1 antibody. This study provides a promising approach for RT sensitization and radio-immunotherapy.

Active Iron-Drug Nanocomplexes Improve Photodynamic and Photothermal Cancer Therapy by Mitigating Tumor Hypoxia and Counteracting Tumor Heat Resistance

Photodynamic therapy (PDT) and photothermal therapy (PTT) offer the advantages of precise temporal and spatial selectivity in cancer treatment, minimizing damage to normal cells while effectively eliminating tumor cells. However, the therapeutic efficacy of phototherapy is always hindered by challenges such as hypoxia and tumor heat resistance. Herein, a pH-responsive metal-drug nanocomplex (denoted as PAFH) comprising hypericin (HYP), apigenin (APG), polyvinylpyrrolidone (PVP), and Fe3+ is developed to enhance the therapeutic efficacy of PDT and PTT. The PAFH nanocomplex exhibits photothermal properties under 808 nm laser irradiation, which can disassociate in response to the acidic tumor microenvironment and the temperature increase induced by PTT, thereby eventually triggering the on-site release of APG and HYP. The released APG inhibits the synthesis of heat shock protein HSP-90, facilitating the PAFH-mediated PTT to kill tumor cells at mild temperature. Additionally, APG alleviates hypoxia and then regulates the expression of hypoxia-inducible factor HIF-1𝛼, increasing cellular oxygen levels to produce singlet oxygen for enhanced HYP-mediated PDT and inhibiting tumor metastasis. Ultimately, this sophisticated nanosystem represents an advanced strategy to promote PDT and PTT by mitigating tumor hypoxia and counteracting tumor heat resistance, significantly improving therapeutic efficacy for precise cancer therapy.

X-ray Induced Persistent Type I Photodynamic Therapy with Enhanced Hypoxia Tolerance and Chemoradiotherapy

The hypoxic tumor microenvironment (TME), inadequate penetration depth of Vis/NIR light, and lack of sustaining reactive oxygen species (ROS) production capability of photosensitizers pose significant obstacles to the widespread clinic applications of photodynamic therapy (PDT). Herein, we developed a "persistent type I X-PDT" platform to simultaneously overcome these three limitations. Such a nanoplatform could generate efficient ROS (•OH and O2•-) under X-ray irradiation in both normoxic and hypoxic environments. The ROS production persists in tumor cells for more than 4 h, even after the X-ray source is removed. Notably, the persistent type I X-PDT does not increase the levels of hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) in tumor cells both in vitro and in vivo. Moreover, to further enhance the radiotherapy efficacy in hypoxic conditions, a Pt (IV) prodrug was also introduced, which can be reduced to cisplatin selectively in tumor cells, functioning not only as a chemodrug but also as a radiosensitizer.

Nanocapsules with dual-targeting of cell and mitochondria functions for enhanced hypoxia-activated drug therapy

The cell and mitochondria dual-targeting nanocapsules reported here could exacerbate tumor hypoxia to activate a hypoxia-activated drug, tirapazamine, producing benzotriazinyl radicals and ˙OH, which are capable of killing tumor cells via DNA damage. In addition, mitochondrial dysfunction can result from the accumulation of ˙OH. This chain reaction triggers a surge in ROS that can effectively increase the therapeutic efficiency of the nanocapsules.

Polydopamine-functionalized capsules: From design to applications

In recent years, polydopamine (PDA)-functionalized capsules have garnered significant interest from researchers in the field of materials, owing to its remarkable properties of adhesion, biocompatibility, photothermal conversion capabilities, chemical reactivity, and so on. At present, numerous studies have reported various structures and morphologies of PDA-functionalized capsules fabricated via diverse strategies, that have found applications across a broad spectrum of disciplines. However, there are few comprehensive and systematic reviews focusing on various preparation strategies of PDA-functionalized capsules with various structures. This paper systematically reviewed the preparation strategies and related applications of PDA-functionalized capsules. These strategies of PDA-functionalized capsules were discussed in detail from four parts including PDA-functionalized capsules based on hollow PDA, mesoporous PDA (MPDA), directly encapsulating emulsion, and surface modification of capsules. Then the review outlined the applications of PDA-functionalized capsules in biomedicine, energy, textiles, and the environment. Furthermore, this review summarized the current research findings on PDA-functionalized capsules and outlines their future development directions. Overall, we aim for this review to inspire researchers and offer valuable guidance for the synthesis and application of advanced PDA-functionalized capsules.

Local Regulation of Mitochondrial Respiratory for Enhancing Photodynamic Therapy and Breaking Chemoresistance in Hypoxia

The hypoxic condition in solid tumors induces therapy resistance, limited therapeutic efficacy, and tumor recurrence, especially for chemotherapy and aerobic photodynamic therapy (PDT). To address this matter, an O2 regulator (SNP@Ato) is designed for breaking chemoresistance and enhancing PDT, which is constructed by loading Atovaquone (Ato) through self-assembly and host-guest interaction between β-cyclodextrin functionalized tetraphenylporphyrin (TPP-CD4) and thioketal-linked camptothecin/azobenzene (Azo-TK-CPT). Specifically, the porphyrin units in SNP@Ato are in "Off state" due to the photoinduced electron transfer (PET) effect between the porphyrin units and azobenzene. After encountering the hypoxic condition in solid tumors, SNP@Ato is dissociated by the cleaved azobenzene on account of over-expressed azo-reductase. Then the mitochondrial respiratory of cancer cells would be suppressed with the participation of Ato, generating a local hypoxia relief for sensitized chemotherapy and enhanced PDT. Accompanied by efficient PDT, the TK linker is broken by ROS, and the CPT is released from the prodrugs. Compared with the SNP group without oxygen-regulator, SNP@Ato exhibits a remarkable improvement of the therapeutic effect against hypoxic tumors in vitro and in vivo. This work proposes a novel paradigm for overcoming hypoxia-induced therapeutic resistance.

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.

A novel red fluorescent and dynamic nanocomposite hydrogel based on chitosan and alginate doped with inclusion complex of carbon dots

Red fluorescent hydrogels possessing injectable and self-healing properties have widespread potential in biomedical field. It is still a challenge to achieve a biomacromolecules based dynamic hydrogels simultaneously combining with excellent red fluorescence, good mechanical properties, and biocompatibility. Here we first explore hydrophilic inclusion complex of (R-CDs@α-CD) derived from hydrophobic red fluorescent carbon dots (R-CDs) and α-cyclodextrin (α-CD), and then achieved a red fluorescent and dynamic polysaccharide R-CDs@α-CD/CEC-l-OSA hydrogel. The nanocomposite hydrogel can be fabricated through controlled doping of red fluorescent R-CDs@α-CD into dynamic polymer networks, taking reversibly crosslinked N-carboxyethyl chitosan (CEC) and oxidized sodium alginate (OSA) as an example. The versatile red fluorescent hydrogel simultaneously combines the features of injection, biocompatibility, and augmented mechanical properties and self-healing behavior, especially in rapid self-recovery even after integration. The R-CDs@α-CD uniformly dispersed into dynamic hydrogel played the role of killing two birds with one stone, that is, endowing red emission of a hydrophilic fluorescent substance, and improving mechanical and self-healing properties as a dynamic nano-crosslinker, via forming hydrogen bonds as reversible crosslinkings. The novel red fluorescent and dynamic hydrogel based on polysaccharides is promising for using as biomaterials in biomedical field.

Biomimetic Iron-Based Nanoparticles Remodel Immunosuppressive Tumor Microenvironment for Metabolic Immunotherapy

Introduction

Immunotherapy has led to a paradigm shift in reinvigorating treatment of cancer. Nevertheless, tumor associated macrophages (TAMs) experience functional polarization on account of the generation of suppressive metabolites, contributing to impaired antitumor immune responses.

Methods

Hence, metabolic reprogramming of tumor microenvironment (TME) can synergistically improve the efficacy of anti-tumor immunotherapy. Herein, we engineered an iron-based nanoplatform termed ERFe3O4 NPs. This platform features hollow Fe3O4 nanoparticles loaded with the natural product emodin, the outer layer is coated with red blood cell membrane (mRBCs) inserted with DSPE-PEG2000-galactose. This effectively modulates lactate production, thereby reversing the tumor immune suppressive microenvironment (TIME).

Results

The ERFe3O4 NPs actively targeted TAMs on account of their ability to bind to M2-like TAMs with high expression of galectin (Mgl). ERFe3O4 NPs achieved efficient ability to reverse TIME via the production of reducing lactate and prompting enrichment iron of high concentrations. Furthermore, ERFe3O4 NPs resulted in heightened expression of CD16/32 and enhanced TNF-α release, indicating promotion of M1 TAMs polarization. In vitro and in vivo experiments revealed that ERFe3O4 NPs induced significant apoptosis of tumor cells and antitumor immune response.

Discussion

This study combines Traditional Chinese Medicine (TCM) with nanomaterials to synergistically reprogram TAMs and reverse TIME, opening up new ideas for improving anti-tumor immunotherapy.

A Versatile Cryomicroneedle Patch for Traceable Photodynamic Therapy

Photodynamic therapy (PDT) continues to encounter multifarious hurdles, stemming from the ineffectual preservation and delivery system of photosensitizers, the dearth of imaging navigation, and the antioxidant/hypoxic tumor microenvironment. Herein, a versatile cryomicroneedle patch (denoted as CMN-CCPH) is developed for traceable PDT. The therapeutic efficacy is further amplified by catalase (CAT)-induced oxygen (O2) generation and Cu2+-mediated glutathione (GSH) depletion. The CMN-CCPH is composed of cryomicroneedle (CMN) as the vehicle and CAT-biomineralized copper phosphate nanoflowers (CCP NFs) loaded with hematoporphyrin monomethyl ether (HMME) as the payload. Importantly, the bioactive function of HMME and CAT can be optimally maintained under the protection of CCPH and CMN for a duration surpassing 60 days, leading to bolstered bioavailability and notable enhancements in PDT efficacy. The in vivo visualization of HMME and oxyhemoglobin saturation (sO2) monitored by fluorescence (FL)/photoacoustic (PA) duplex real-time imaging unveils the noteworthy implications of CMN-delivered CCPH for intratumoral enrichment of HMME and O2 with reduced systemic toxicity. This versatile CMN patch demonstrates distinct effectiveness in neoplasm elimination, underscoring its promising clinical prospects.

Red Blood Cell-Like Poly(ethylene glycol) Particles: Influence of Particle Stiffness on Biological Behaviors

Cell-like particles represent a category of synthetic particles designed to emulate the structures or functions of natural cells. Herein, we present the assembly of cell-like poly(ethylene glycol) (PEG) particles with different stiffnesses and shapes via replication of animal cells and investigate the impact of particle stiffness on their biological behaviors. As a proof of concept, we fabricate red blood cell-like and spherical PEG particles with varying cross-linking densities. A systematic exploration of their properties, encompassing morphology, stiffness, deformability, and biodistribution, reveal the vital influence of particle stiffness on in vivo fate, elucidating its role in governing the traversal of capillaries and the dynamic interactions with phagocytic cells.

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.

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

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

Study of Iron Complex Photosensitizer with Hollow Double-Shell Nano Structure Used to Enhance Ferroptosis and Photodynamic Therapy

Ferroptosis therapy, which uses ferroptosis inducers to produce lethal lipid peroxides and induce tumor cell death, is considered a promising cancer treatment strategy. However, challenges remain regarding how to increase the accumulation of reactive oxygen species (ROS) in the tumor microenvironment (TME) to enhance antitumor efficacy. In this study, a hyaluronic acid (HA) encapsulated hollow mesoporous manganese dioxide (H-MnO2) with double-shell nanostructure is designed to contain iron coordinated cyanine near-infrared dye IR783 (IR783-Fe) for synergistic ferroptosis photodynamic therapy against tumors. The nano photosensitizer IR783-Fe@MnO2-HA, in which HA actively targets the CD44 receptor, subsequently dissociates and releases Fe3+ and IR783 in acidic TME. First, Fe3+ consumes glutathione to produce Fe2+, which promotes the Fenton reaction in cells to produce hydroxyl free radicals (·OH) and induce ferroptosis of tumor cells. In addition, MnO2 catalyzes the production of O2 from H2O2 and enhances the production of singlet oxygen (1O2) by IR783 under laser irradiation, thus increasing the production and accumulation of ROS to provide photodynamic therapy. The highly biocompatible IR783-Fe@MnO2-HA nano-photosensitizers have exhibited tumor-targeting ability and efficient tumor inhibition in vivo due to the synergistic effect of photodynamic and ferroptosis antitumor therapies.

A Tumor Environment-Activated Photosensitized Biomimetic Nanoplatform for Precise Photodynamic Immunotherapy of Colon Cancer

Aggressive nature of colon cancer and current imprecise therapeutic scenarios simulate the development of precise and effective treatment strategies. To achieve this, a tumor environment-activated photosensitized biomimetic nanoplatform (PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM) is fabricated by encapsulating metal-organic framework loaded with developed photosensitizer PEG2000-SiNcTI-Ph and immunoadjuvant CpG oligodeoxynucleotide within fusion cell membrane expressing programmed death protein 1 (PD-1) and cluster of differentiation 47 (CD47). By stumbling across, systematic evaluation, and deciphering with quantum chemical calculations, a unique attribute of tumor environment (low pH plus high concentrations of adenosine 5'-triphosphate (ATP))-activated photodynamic effect sensitized by long-wavelength photons is validated for PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM, advancing the precision of cancer therapy. Moreover, PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM evades immune surveillance to target CT26 colon tumors in mice mediated by CD47/signal regulatory proteins α (SIRPα) interaction and PD-1/programmed death ligand 1 (PD-L1) interaction, respectively. Tumor environment-activated photodynamic therapy realized by PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM induces immunogenic cell death (ICD) to elicit anti-tumor immune response, which is empowered by enhanced dendritic cells (DC) uptake of CpG and PD-L1 blockade contributed by the nanoplatform. The photodynamic immunotherapy efficiently combats primary and distant CT26 tumors, and additionally generates immune memory to inhibit tumor recurrence and metastasis. The nanoplatform developed here provides insights for the development of precise cancer therapeutic strategies.

New insights into red blood cells in tumor precision diagnosis and treatment

Red blood cells (RBCs), which function as material transporters in organisms, are rich in materials that are exchanged with metabolically active tumor cells. Recent studies have demonstrated that tumor cells can regulate biological changes in RBCs, including influencing differentiation, maturation, and morphology. RBCs play an important role in tumor development and immune regulation. Notably, the novel scientific finding that RBCs absorb fragments of tumor-carrying DNA overturns the conventional wisdom that RBCs do not contain nucleic acids. RBC membranes are excellent biomimetic materials with significant advantages in terms of their biocompatibility, non-immunogenicity, non-specific adsorption resistance, and biodegradability. Therefore, RBCs provide a new research perspective for the development of tumor liquid biopsies, molecular imaging, drug delivery, and other tumor precision diagnosis and treatment technologies.

Nanomaterial-related hemoglobin-based oxygen carriers, with emphasis on liposome and nano-capsules, for biomedical applications: current status and future perspectives

Oxygen is necessary for life and plays a key pivotal in maintaining normal physiological functions and treat of diseases. Hemoglobin-based oxygen carriers (HBOCs) have been studied and developed as a replacement for red blood cells (RBCs) in oxygen transport due to their similar oxygen-carrying capacities. However, applications of HBOCs are hindered by vasoactivity, oxidative toxicity, and a relatively short circulatory half-life. With advancements in nanotechnology, Hb encapsulation, absorption, bioconjugation, entrapment, and attachment to nanomaterials have been used to prepare nanomaterial-related HBOCs to address these challenges and pend their application in several biomedical and therapeutic contexts. This review focuses on the progress of this class of nanomaterial-related HBOCs in the fields of hemorrhagic shock, ischemic stroke, cancer, and wound healing, and speculates on future research directions. The advancements in nanomaterial-related HBOCs are expected to lead significant breakthroughs in blood substitutes, enabling their widespread use in the treatment of clinical diseases.

Pt-Decorated Gold Nanoflares for High-Fidelity Phototheranostics: Reducing Side-Effects and Enhancing Cytotoxicity toward Target Cells

Functionalized with the Au-S bond, gold nanoflares have emerged as promising candidates for theranostics. However, the presence of intracellular abundantly biothiols compromises the conventional Au-S bond, leading to the unintended release of cargoes and associated side-effects on non-target cells. Additionally, the hypoxic microenvironment in diseased regions limits treatment efficacy, especially in photodynamic therapy. To address these challenges, high-fidelity photodynamic nanoflares constructed on Pt-coated gold nanoparticles (Au@Pt PDNF) were communicated to avoid false-positive therapeutic signals and side-effects caused by biothiol perturbation. Compared with conventional photodynamic gold nanoflares (AuNP PDNF), the Au@Pt PDNF were selectively activated by cancer biomarkers and exhibited high-fidelity phototheranostics while reducing side-effects. Furthermore, the ultrathin Pt-shell catalysis was confirmed to generate oxygen which alleviated hypoxia-related photodynamic resistance and enhanced the antitumor effect. This design might open a new venue to advance theranostics performance and is adaptable to other theranostic nanomaterials by simply adding a Pt shell.

Lysophosphatidic acid responsive photosensitive supramolecular organic frameworks for tumor imaging, drug loading, and photodynamic therapy

Supramolecular organic frameworks have been widely applied for biological detection and drug delivery. In this study, a supramolecular organic framework (SOF) is constructed through the self-assembly of a highly photosensitive triarylphosphine oxide guest molecule, OTPP-6-Methyl, with cucurbit [8] uril (CB [8]). The formation of the SOF gradually enhances the weak fluorescence of OTPP-6-Methyl owing to the restriction of the molecular folding motion. Although the high positive charge of OTPP-6-Methyl facilitates binding to various negatively charged substances, the SOF system only demonstrated an obvious fluorescence response to LPA, a biomarker of ovarian cancer, via the disassembly of SOF and subsequent binding of OTPP-6-Methyl with LPA. The fluorescence changes during the entire process are insufficient to allow the sensitive detection of LPA; thus, we further designed a FRET system by introducing Cy5, which can act as an energy receptor to achieve a ratiometric readout for LPA. The tumor-targeting cRGD group was introduced into the SOF system as part of another guest molecule, OTPP-5-M-1-cRGD, to improve the tumor-targeting ability of the SOF system. The SOF system further improves the photosensitivity of guest molecules, and is therefore used in the in vivo imaging of ovarian cancer subcutaneous tumors and as a DDS for loading DOX for the combined in vivo chemotherapy and photodynamic treatment of tumors.

Toward Type I/II ROS Generation Photoimmunotherapy by Molecular Engineering of Semiconducting Perylene Diimide

As prospective phototheranostic agents for cancer imaging and therapy, semiconducting organic molecule-based nanomedicines are developed. However, near-infrared (NIR) emission, and tunable type I (O2 • -) and type II (1O2) photoinduced reactive oxygen species (ROS) generation to boost cancer photoimmunotherapy remains a big challenge. Herein, a series of D-π-A structures, NIR absorbing perylene diimides (PDIs) with heavy atom bromide modification at the bay position of PDIs are prepared for investigating the optimal photoinduced type I/II ROS generation. The heavy atom effect has demonstrated a reduction of molecular ∆EST and promotion of the intersystem crossing processes of PDIs, enhancing the photodynamic therapy (PDT) efficacy. The modification of three bromides and one pyrrolidine at the bay position of PDI (TBDT) has demonstrated the best type I/II PDT performance by batch experiments and theoretical calculations. TBDT based nanoplatforms (TBDT NPs) enable type I/II PDT in the hypoxic tumor microenvironment as a strong immunogenic cell death (ICD) inducer. Moreover, TBDT NPs showing NIR emission allow in vivo bioimaging guided phototherapy of tumor. This work uses novel PDIs with adjustable type I/II ROS production to promote antitumor immune response and accomplish effective tumor eradication, consequently offering molecular guidelines for building high-efficiency ICD inducers.

CB[8]- and triarylboron-based supramolecular organic framework for microRNA detection, tumor-targeted drug delivery, and photodynamic therapy

Supramolecular organic frameworks (SOFs) are widely used for biological detection and drug delivery. In this study, a SOF system was fabricated through the self-assembly of photosensitive triarylboron (TAB), TAB-6-methyl, and CB[8]. The maximum fluorescence emission of TAB-6-methyl was greatly enhanced and red-shifted from 560 nm to 610 nm after SOF formation. The SOF can specifically respond to a microRNA by dissembling and then combining with microRNA, which is accompanied by a fluorescence shift from 610 nm to 560 nm, thus providing a ratiometric readout for microRNA detection. The photosensitivity of TAB-6-methyl can be further improved by forming a SOF, which can be used in photodynamic therapy. By constructing another guest molecule, TAB-5-1-cRGD, we successfully embedded cRGD in the SOF system to improve its tumor-targeting ability. Moreover, we used this SOF system as a fluorescence imaging probe for targeted tumor imaging and as a drug carrier system for loading DOX to achieve combined photodynamic and chemotherapy treatment of tumors.

Induction of ferroptosis by photodynamic therapy and enhancement of antitumor effect with ferroptosis inducers

BACKGROUND

Photodynamic therapy (PDT) is an effective tumor treatment that involves the administration of a photosensitizer to generate cytotoxic 1O2 [reactive oxygen species (ROS)] from molecular oxygen that is produced from energy absorption following tumor irradiation at specific wavelengths. Ferroptosis is induced by the disruption of the glutathione peroxidase 4 (GPX4) antioxidant system, leading to lipid peroxidation. We hypothesized that talaporfin sodium-photodynamic therapy (TS-PDT)-generated ROS would lead to ferroptosis via accumulation of lipid peroxidation.

METHODS

Cell viability assay in TS-PDT-treated cells in combination with a ferroptosis inhibitor (ferrostatin-1: Fer-1) or ferroptosis inducers (imidazole ketone erastin: IKE, Ras-selective lethal 3: RSL3) was performed. Accumulation of lipid peroxidation, GPX4 antioxidant system and cystine/glutamate antiporter (system xc-) activity in TS-PDT-treated cells was investigated. In xenograft mice, the antitumor effect of TS-PDT in combination with ferroptosis inducers (IKE or sorafenib) was examined.

RESULTS

TS-PDT-induced cell death was partly suppressed by Fer-1 and accompanied by lipid peroxidation. TS-PDT combined with IKE or RSL3 enhanced the induction of cell death. TS-PDT inhibited cystine uptake activity via system xc-. In vivo, the combination of TS-PDT and ferroptosis inducers (IKE or sorafenib) reduced tumor volume.

CONCLUSION

This study found that the mechanism underlying TS-PDT-induced ferroptosis constitutes direct lipid peroxidation by the generated ROS, and the inhibition of system xc-, and that the combination of a ferroptosis inducer with TS-PDT enhances the antitumor effect of TS-PDT. Our findings suggest that ferroptosis-inducing therapies combined with PDT may benefit cancer patients.

Photoelectrons Sequentially Regulate Antibacterial Activity and Osseointegration of Titanium Implants

Titanium implants are widely used ; however, implantation occasionally fails due to infections during the surgery or poor osseointegration after the surgery. To solve the problem, an intelligent functional surface on titanium implant that can sequentially eradicate bacteria biofilm at the initial period and promote osseointegration at the late period of post-surgery time is designed. Such surfaces can be excited by near infrared light (NIR), with rare earth nanoparticles to upconvert the NIR light to visible range and adsorb by Au nanoparticles, supported by titanium oxide porous film on titanium implants. Under NIR irradiation, the implant converts the energy of phonon to hot electrons and lattice vibrations, while the former flows directly to the contact substance or partially reacts with the surrounding to generate reactive oxygen species, and the latter leads to the local temperature increase. The biofilm or microbes on the implant surface can be eradicated by NIR treatment in vitro and in vivo. Additionally, the surface exhibits superior biocompatibility for cell survival, adhesion, proliferation, and osteogenic differentiation, which provides the foundation for osseointegration. In vivo implantation experiments demonstrate osseointegration is also promoted. This work thus demonstrates NIR-generated electrons can sequentially eradicate biofilms and regulate the osteogenic process, providing new solutions to fabricate efficient implant surfaces.

Copper indium selenium nanomaterials for photo-amplified immunotherapy through simultaneously enhancing cytotoxic T lymphocyte recruitment and M1 polarization of macrophages

Photoactivated immunotherapy has promising therapeutic efficacy for treating malignancies, especially metastatic tumors. In this study, an erythrocyte membrane-encapsulated copper indium selenium (RCIS) semiconductor nanomaterial was developed to eliminate primary and metastatic tumors, in which copper ions can induce chemodynamic performance, and the narrow band gap endows RCIS with the properties of near-infrared (NIR) light-activated photothermal and photodynamic amplified immunotherapy. Furthermore, RCIS can be used as a nanocarrier to form RNCIS nanoparticles (NPs) by loading NLG919, which blocks the indoleamine 2,3-dioxygenase-1. Under NIR light irradiation, RNCIS NPs release NLG919 at tumor sites via photothermal properties, thereby promoting the recruitment of cytotoxic T lymphocytes and M1 polarization of macrophages, targeting the activation and amplification of immune responses. Herein, in vitro and in vivo studies showed that RNCIS NPs effectively kill cancer cells and eliminate primary and metastatic tumors. Therefore, this study suggests that semiconductor nanomaterials with narrow bandgaps have great potential as photoimmunotherapy agents and NIR light-responsive nanocarriers for controlled release, providing a great paradigm for synergetic tumor photoimmunotherapy. STATEMENT OF SIGNIFICANCE: The Erythrocyte membrane-coated, NLG919-loaded copper indium selenium (RNCIS) semiconductor was designed for eliminating primary and metastatic tumors. RNCIS exhibits chemodynamic, photodynamic, and photothermal activated immunotherapy by inhibiting indoleamine 2,3-dioxygenase-1. This can enhance the recruitment of cytotoxic T lymphocyte and M1 polarization of macrophage, leading to higher synergetic photo-immune therapeutic efficacy.

NIR diagnostic imaging of triple-negative breast cancer and its lymph node metastasis for high-efficiency hypoxia-activated multimodal therapy

BACKGROUND

Triple-negative breast cancer (TNBC) possesses special biological behavior and clinicopathological characteristics, which is highly invasive and propensity to metastasize to lymph nodes, leading to a worse prognosis than other types of breast cancer. Thus, the development of an effective therapeutic method is significant to improve the survival rate of TNBC patients.

RESULTS

In this work, a liposome-based theranostic nanosystem (ILA@Lip) was successfully prepared by simultaneously encapsulating IR 780 as the photosensitizer and lenvatinib as an anti-angiogenic agent, together with banoxantrone (AQ4N) molecule as the hypoxia-activated prodrug. The ILA@Lip can be applied for the near-infrared (NIR) fluorescence diagnostic imaging of TNBC and its lymph node metastasis for multimodal therapy. Lenvatinib in ILA@Lip can inhibit angiogenesis by cutting oxygen supply, thereby leading to enhanced hypoxia levels. Meanwhile, large amounts of reactive oxygen species (ROS) were produced while IR 780 was irradiated by an 808 nm laser, which also rapidly exhausted oxygen in tumor cells to worsen tumor hypoxia. Through creating an extremely hypoxic in TNBC, the conversion of non-toxic AQ4N to toxic AQ4 was much more efficiency for hypoxia-activated chemotherapy. Cytotoxicity assay of ILA@Lip indicated excellent biocompatibility with normal cells and tissues, but showed high toxicity in hypoxic breast cancer cells. Also, the in vivo tumors treated by the ILA@Lip with laser irradiation were admirably suppressed in both subcutaneous tumor model and orthotopic tumor models.

CONCLUSION

Utilizing ILA@Lip is a profound strategy to create an extremely hypoxic tumor microenvironment for higher therapeutic efficacy of hypoxia-activated chemotherapy, which realized collective suppression of tumor growth and has promising potential for clinical translation.

Strategic Design of Conquering Hypoxia in Tumor for Advanced Photodynamic Therapy

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

Polydopamine-containing nano-systems for cancer multi-mode diagnoses and therapies: A review

Polydopamine (PDA) has fascinating properties such as inherent biocompatibility, simple preparation, strong near-infrared absorption, high photothermal conversion efficiency, and strong metal ion chelation, which have catalyzed extensive research in PDA-containing multifunctional nano-systems particularly for biomedical applications. Thus, it is imperative to overview synthetic strategies of various PDA-containing nanoparticles (NPs) for state-of-the-art cancer multi-mode diagnoses and therapies applications, and offer a timely and comprehensive summary. In this review, we will focus on the synthetic approaches of PDA NPs, and summarize the construction strategies of PDA-containing NPs with different structure forms. Additionally, the application of PDA-containing NPs in bioimaging such as photoacoustic imaging, fluorescence imaging, magnetic resonance imaging and other imaging modalities will be reviewed. We will especially offer an overview of their therapeutic applications in tumor chemotherapy, photothermal therapy, photodynamic therapy, photocatalytic therapy, sonodynamic therapy, radionuclide therapy, gene therapy, immunotherapy and combination therapy. At the end, the current trends, limitations and future prospects of PDA-containing nano-systems will be discussed. This review aims to provide guidelines for new scientists in the field of how to design PDA-containing NPs and what has been achieved in this area, while offering comprehensive insights into the potential of PDA-containing nano-systems used in cancer diagnosis and treatment.

Tracking Research on Hemoglobin-Based Oxygen Carriers: A Scientometric Analysis and In-Depth Review

Numerous studies on the formulation and clinical applications of novel hemoglobin-based oxygen carriers (HBOCs) are reported in the scientific literature. However, there are fewer scientometric analysis related to HBOCs. Here, we illustrate recent studies on HBOCs using both a scientometric analysis approach and a scope review method. We used the former to investigate research on HBOCs from 1991 to 2022, exploring the current hotspots and research trends, and then we comprehensively analyzed the relationship between concepts based on the keyword analysis. The evolution of research fields, knowledge structures, and research topics in which HBOCs located are revealed by scientometric analysis. The elucidation of type, acting mechanism, potential clinical practice, and adverse effects of HBOCs helps to clarify the prospects of this biological agent. Scientometrics analyzed 1034 publications in this research field, and these findings provide a promising roadmap for further study.

Oxygen-releasing biomaterials for regenerative medicine

Oxygen is critical to the survival, function and fate of mammalian cells. Oxygen tension controls cellular behavior through metabolic programming, which in turn controls tissue regeneration. A variety of biomaterials with oxygen-releasing capabilities have been developed to provide oxygen supply to ensure cell survival and differentiation for therapeutic efficacy, and to prevent hypoxia-induced tissue damage and cell death. However, controlling the oxygen release with spatial and temporal accuracy is still technically challenging. In this review, we provide a comprehensive overview of organic and inorganic materials available as oxygen sources, including hemoglobin-based oxygen carriers (HBOCs), perfluorocarbons (PFCs), photosynthetic organisms, solid and liquid peroxides, and some of the latest materials such as metal-organic frameworks (MOFs). Additionally, we introduce the corresponding carrier materials and the oxygen production methods and present state-of-the-art applications and breakthroughs of oxygen-releasing materials. Furthermore, we discuss the current challenges and the future perspectives in the field. After reviewing the recent progress and the future perspectives of oxygen-releasing materials, we predict that smart material systems that combine precise detection of oxygenation and adaptive control of oxygen delivery will be the future trend for oxygen-releasing materials in regenerative medicine.

Light-Triggered Nitric Oxide Nanogenerator with High l-Arginine Loading for Synergistic Photodynamic/Gas/Photothermal Therapy

The development of nanomedicines that combine photothermal therapy (PTT) with photodynamic therapy (PDT) is considered promising for cancer treatment, but still faces the challenge of enhancing tumoricidal efficiency. Fortunately, apart from the well-acknowledged effect on direct tumor cell-killing, nitric oxide (NO) is also considered to be effective for the enhancement of both PTT and PDT. However, both the low loading efficiency of NO precursor and the short half-life time and diffusion distance of NO hamper the synergistic therapeutic efficacy of NO. Taking the aforementioned factors into account, a mitochondria-targeted nitric oxide nanogenerator, EArgFe@Ce6, is constructed to achieve high loading of the NO donor l-Arginine (l-Arg) for synergistic photodynamic/gas/photothermal therapy upon single 660 nm light irradiation. The coordination of epigallocatechin gallate (EGCG) and ferric ions (Fe3+ ) provides EArgFe@Ce6 supreme photothermal capability to perform low-temperature PTT (mPTT). EGCG endows EArgFe@Ce6 with mitochondria-targeting capability and meanwhile favors hypoxia alleviation for enhanced PDT. The PDT-produced massive reactive oxygen species (ROS) further catalyzes l-Arg to generate a considerable amount of NO to perform gas therapy and sensitize both mPTT and PDT. In vitro and in vivo studies demonstrate that the synergistic photodynamic/gas/photothermal therapy triggered by single 660 nm light irradiation is highly effective for tumor treatments.

Recent Advances in Nanoplatform Construction Strategy for Alleviating Tumor Hypoxia

Hypoxia is a typical feature of most solid tumors and has important effects on tumor cells' proliferation, invasion, and metastasis. This is the key factor that leads to poor efficacy of different kinds of therapy including chemotherapy, radiotherapy, photodynamic therapy, etc. In recent years, the construction of hypoxia-relieving functional nanoplatforms through nanotechnology has become a new strategy to reverse the current situation of tumor microenvironment hypoxia and improve the effectiveness of tumor treatment. Here, the main strategies and recent progress in constructing nanoplatforms are focused on to directly carry oxygen, generate oxygen in situ, inhibit mitochondrial respiration, and enhance blood perfusion to alleviate tumor hypoxia. The advantages and disadvantages of these nanoplatforms are compared. Meanwhile, nanoplatforms based on organic and inorganic substances are also summarized and classified. Through the comprehensive overview, it is hoped that the summary of these nanoplatforms for alleviating hypoxia could provide new enlightenment and prospects for the construction of nanomaterials in this field.

Ultrasound-Triggered Cascade Amplification of Nanotherapy

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

Hyperbaric Oxygen Activates Enzyme-Driven Cascade Reactions for Cooperative Cancer Therapy and Cancer Stem Cells Elimination

Tumor starvation induced by intratumor glucose depletion emerges as a promising strategy for anticancer therapy. However, its antitumor potencies are severely compromised by intrinsic tumor hypoxia, low delivery efficiencies, and undesired off-target toxicity. Herein, a multifunctional cascade bioreactor (HCG), based on the self-assembly of pH-responsive hydroxyethyl starch prodrugs, copper ions, and glucose oxidase (GOD), is engineered, empowered by hyperbaric oxygen (HBO) for efficient cooperative therapy against aggressive breast cancers. Once internalized by tumor cells, HCG undergoes disassembly and releases cargoes in response to acidic tumor microenvironment. Subsequently, HBO activates GOD-catalyzed oxidation of glucose to H2 O2 and gluconic acid by ameliorating tumor hypoxia, fueling copper-catalyzed •OH generation and pH-responsive drug release. Meanwhile, HBO degrades dense tumor extracellular matrix, promoting tumor accumulation and penetration of HCG. Moreover, along with the consumption of glucose and the redox reaction of copper ions, the antioxidant capacity of tumor cells is markedly reduced, collectively boosting oxidative stress. As a result, the combination of HCG and HBO can not only remarkably suppress the growth of orthotopic breast tumors but also restrain pulmonary metastases by inhibiting cancer stem cells. Considering the clinical accessibility of HBO, this combined strategy holds significant translational potentials for GOD-based therapies.

A Metal-Polyphenol-Based Oxygen Economizer and Fenton Reaction Amplifier for Self-Enhanced Synergistic Photothermal/Chemodynamic/Chemotherapy

To overcome the limitations of doxorubicin (DOX) chemotherapy, nanomedicines that integrate additional photothermal therapy (PTT) and chemodynamic therapy (CDT) strategies are highlighted as promising alternatives for the treatment of malignant tumors. However, time-consuming preparation processes, biosafety concerns, and the bottlenecks of individual therapeutic modalities often limit the practical applications of this strategy. To address these issues, this work designs an oxygen economizer that additionally serves as a Fenton reaction amplifier through the simple assembly of epigallocatechin gallate (EGCG), pluronic F-127 (PF127), iron (III) ions, and doxorubicin (DOX) for the enhancement of synergistic PTT/CDT/chemotherapy. The resulting nanoformulation, EFPD, can target mitochondria and inhibit cell respiration to reduce O2 consumption, thus boosting DOX-mediated H2 O2 generation for enhanced CDT and simultaneously improving hypoxia-limited DOX chemotherapy efficacy. Moreover, the coordination between EGCG and Fe3+ provides EFPD with excellent photothermal conversion efficiencies (η = 34.7%) for PTT and photothermal-accelerated drug release. Experimental results indicate that EFPD-mediated synergistic enhancement of PTT/CDT/chemotherapy can achieve excellent therapeutic outcomes, including enhanced ablation of solid tumors, reduced metastasis and cardiotoxicity, and extended life spans.

Nanoparticle-mediated synergistic anticancer effect of ferroptosis and photodynamic therapy: Novel insights and perspectives

Current antitumor monotherapy has many limitations, highlighting the need for novel synergistic anticancer strategies. Ferroptosis is an iron-dependent form of nonapoptotic cell death that plays a pivotal regulatory role in tumorigenesis and treatment. Photodynamic therapy (PDT) causes irreversible chemical damage to target lesions and is widely used in antitumor therapy. However, PDT's effectiveness is usually hindered by several obstacles, such as hypoxia, excess glutathione (GSH), and tumor resistance. Ferroptosis improves the anticancer efficacy of PDT by increasing oxygen and reactive oxygen species (ROS) or reducing GSH levels, and PDT also enhances ferroptosis induction due to the ROS effect in the tumor microenvironment (TME). Strategies based on nanoparticles (NPs) can subtly exploit the potential synergy of ferroptosis and PDT. This review explores recent advances and current challenges in the landscape of the underlying mechanisms regulating ferroptosis and PDT, as well as nano delivery system-mediated synergistic anticancer activity. These include polymers, biomimetic materials, metal organic frameworks (MOFs), inorganics, and carrier-free NPs. Finally, we highlight future perspectives of this novel emerging paradigm in targeted cancer therapies.

Recent advances in micro-sized oxygen carriers inspired by red blood cells

Supplementing sufficient oxygen to cells is always challenging in biomedical engineering fields such as tissue engineering. Originating from the concept of a 'blood substitute', nano-sized artificial oxygen carriers (AOCs) have been studied for a long time for the optimization of the oxygen supplementation and improvement of hypoxia environments in vitro and in vivo. When circulating in our bodies, micro-sized human red blood cells (hRBCs) feature a high oxygen capacity, a unique biconcave shape, biomechanical and rheological properties, and low frictional surfaces, making them efficient natural oxygen carriers. Inspired by hRBCs, recent studies have focused on evolving different AOCs into microparticles more feasibly able to achieve desired architectures and morphologies and to obtain the corresponding advantages. Recent micro-sized AOCs have been developed into additional categories based on their principal oxygen-carrying or oxygen-releasing materials. Various biomaterials such as lipids, proteins, and polymers have also been used to prepare oxygen carriers owing to their rapid oxygen transfer, high oxygen capacity, excellent colloidal stability, biocompatibility, suitable biodegradability, and long storage. In this review, we concentrated on the fabrication techniques, applied biomaterials, and design considerations of micro-sized AOCs to illustrate the advances in their performances. We also compared certain recent micro-sized AOCs with hRBCs where applicable and appropriate. Furthermore, we discussed existing and potential applications of different types of micro-sized AOCs.

Recent Developments in Nanoparticle-Based Photo-Immunotherapy for Cancer Treatment

Phototherapy is an emerging approach for cancer treatment that is effective at controlling the growth of primary tumors. In the presence of light irradiation, photothermal and photodynamic agents that are delivered to tumor sites can induce local hyperthermia and the production of reactive oxygen species, respectively, that directly eradicate cancer cells. Nanoparticles, characterized by their small size and tunable physiochemical properties, have been widely utilized as carriers for phototherapeutic agents to improve their biocompatibility and tumor-targeted delivery. Nanocarriers can also be used to implement various codelivery strategies for further enhancing phototherapeutic efficiency. More recently, there has been considerable interest in augmenting the immunological effects of nanoparticle-based phototherapies, which can yield durable and systemic antitumor responses. This review provides an overview of recent developments in using nanoparticle technology to achieve photo-immunotherapy.

Precise manipulation of circadian clock using MnO2 nanocapsules to amplify photodynamic therapy for osteosarcoma

Circadian rhythm (CR) disruption contributes to tumor initiation and progression, however the pharmacological targeting of circadian regulators reversely inhibits tumor growth. Precisely controlling CR in tumor cells is urgently required to investigate the exact role of CR interruption in tumor therapy. Herein, based on KL001, a small molecule that specifically interacts with the clock gene cryptochrome (CRY) functioning at disruption of CR, we fabricated a hollow MnO2 nanocapsule carrying KL001 and photosensitizer BODIPY with the modification of alendronate (ALD) on the surface (H-MnSiO/K&B-ALD) for osteosarcoma (OS) targeting. The H-MnSiO/K&B-ALD nanoparticles reduced the CR amplitude in OS cells without affecting cell proliferation. Furthermore, nanoparticles-controlled oxygen consumption by inhibiting mitochondrial respiration via CR disruption, thus partially overcoming the hypoxia limitation for photodynamic therapy (PDT) and significantly promoting PDT efficacy. An orthotopic OS model demonstrated that KL001 significantly enhanced the inhibitory effect of H-MnSiO/K&B-ALD nanoparticles on tumor growth after laser irradiation. CR disruption and oxygen level enhancement induced by H-MnSiO/K&B-ALD nanoparticles under laser irradiation were also confirmed in vivo. This discovery first demonstrated the potential of CR controlling for tumor PDT ablation and provided a promising strategy for overcoming tumor hypoxia.

Near Infrared-Activatable Methylene Blue Polypeptide Codelivery of the NO Prodrug via π-π Stacking for Cascade Reactive Oxygen Species Amplification-Mediated Photodynamic Therapy

The application of photodynamic therapy (PDT) has attracted remarkable interest in cancer treatment because of the advantages of noninvasiveness and spatiotemporal selectivity. However, the PDT efficiency is considerably limited by photosensitizer (PS) quenching and severe hypoxia in solid tumors. Herein, a kind of near infrared (NIR)-activatable methylene blue (MB) peptide nanocarrier was developed for codelivery of nitric oxide (NO) prodrug JSK, expecting a cascade of reactive oxygen species (ROS) amplification-mediated antitumor PDT. In detail, MB was conjugated to water-soluble polyethylene glycol-polylysine (PEG-PLL) through NIR-photocleavable 10-N-carbamoyl bonds, and the subsequent amphiphilic conjugates (mPEG-PLL-MB) self-assembled into nanoparticles (NPs), which allowed JSK codelivery via π-π stacking interactions. MB in quenched state in mPEG-PLL-MB/JSK NPs could be photoactivated by NIR light locoregionally in a controlled manner due to the photocleavage of carbamoyl bonds. Apart from ROS production, assembly disturbance and even disintegration of mPEG-PLL-MB/JSK occurred along with MB activation that subsequently freed JSK, which was further triggered by intracellularly overexpressed glutathione (GSH) and glutathione S-transferase (GST) to sustain the release of NO. NO then served as a hypoxia relief agent through inhibition of cellular respiration to economize O₂, cooperating with MB activation and GSH depletion, which synergistically enabled a cascade of ROS amplification to augment PDT for mitochondrial apoptosis-mediated tumor inhibition in vitro and in vivo. Therefore, this pioneering strategy of cascade amplification of ROS addressed the key issues of PS inactivation, hypoxia resistance, and ROS neutralization in a three-pronged approach, which hold great promise in efficient antitumor PDT.

A Novel "Inside-Out" Intraocular Nanomedicine Delivery Mode for Nanomaterials' Biological Effect Enhanced Choroidal Neovascularization Occlusion and Microenvironment Regulation

Photodynamic therapy (PDT) is commonly used in choroidal neovascularization (CNV) treatment due to the superior light transmittance of the eye. However, PDT often leads to surrounding tissue damage and further microenvironmental deterioration, including exacerbated hypoxia, inflammation, and secondary neovascularization. In this work, Pt nanoparticles (NPs) and Au NPs decorated zeolitic imidazolate framework-8 nanoplatform is developed to load indocyanine green for precise PDT and microenvironment amelioration, which can penetrate the internal limiting membrane through Müller cells endocytosis and target to CNV by surface-grafted cyclo(Arg-Gly-Asp-d-Phe-Lys) after intravitreal injection. The excessive H₂ O₂ in the CNV microenvironment is catalyzed by catalase-like Pt NPs for hypoxia relief and enhanced PDT occlusion of neovascular. Meanwhile, Au NPs show significant anti-inflammatory and anti-angiogenesis properties in regulating macrophages and blocking vascular endothelial growth factor (VEGF). Compared with verteporfin treatment, the mRNA expressions of hypoxia-inducible factor-1α and VEGF in the nanoplatform group are downregulated by 90.2% and 81.7%, respectively. Therefore, the nanoplatform realizes a comprehensive CNV treatment effect based on the high drug loading capacity and biosafety. The CNV treatment mode developed in this work provides a valuable reference for treating other diseases with similar physiological barriers that limit drug delivery and similar microenvironment.

Nanomedicine-mediated ferroptosis targeting strategies for synergistic cancer therapy

Apoptosis-based treatment plays an important role in regulating the death of tumor cells (e.g., chemotherapy, radiotherapy, and immunotherapy). Nevertheless, cancer cells can escape surveillance from apoptosis-associated signaling by bypassing other biological pathways and thus result in considerable resistance to therapies. Significantly, ferroptosis, a newly identified type of regulated cell death that is characterized by iron-dependent and lipid peroxidation accumulation, has aroused great research interest in cancer therapy. Increasing approaches have been developed to induce ferroptosis of tumor cells, including using clinically approved drugs, experimentally used compounds, and nanomedicine formulations. More importantly, the emerging nanomedicine-based strategy has made great advances in tumor treatment because of the promising targeting efficacy and enhanced therapeutic effects. In this review, we mainly overview state-of-the-art research on nanomedicine-mediated ferroptosis targeting strategies for synergistic cancer therapies, such as immunotherapy, chemotherapy, radiotherapy, and photothermal therapy. The potential targeting mechanism of nanomedicine for ferroptosis induction was also included. Finally, the future development of nanomedicine in the field of ferroptosis-based cell death in tumor treatment will be envisioned, aiming to provide new insight for tumor treatment in the clinic.

Chemically engineering cells for precision medicine

Cell-based therapy holds great potential to address unmet medical needs and revolutionize the healthcare industry, as demonstrated by several therapeutics such as CAR-T cell therapy and stem cell transplantation that have achieved great success clinically. Nevertheless, natural cells are often restricted by their unsatisfactory in vivo trafficking and lack of therapeutic payloads. Chemical engineering offers a cost-effective, easy-to-implement engineering tool that allows for strengthening the inherent favorable features of cells and confers them new functionalities. Moreover, in accordance with the trend of precision medicine, leveraging chemical engineering tools to tailor cells to accommodate patients individual needs has become important for the development of cell-based treatment modalities. This review presents a comprehensive summary of the currently available chemically engineered tools, introduces their application in advanced diagnosis and precision therapy, and discusses the current challenges and future opportunities.

Ferroptosis: challenges and opportunities for nanomaterials in cancer therapy

Ferroptosis, a completely new form of regulated cell death, is mainly caused by an imbalance between oxidative damage and reductive protection and has shown great anti-cancer potential. However, existing small-molecule ferroptosis inducers have various limitations, such as poor water solubility, drug resistance and low targeting ability, hindering their clinical applications. Nanotechnology provides new opportunities for ferroptosis-driven tumor therapy. Especially, stimuli-responsive nanomaterials stand out among others and have been widely researched because of their unique spatiotemporal control advantages. Therefore, it's necessary to summarize the application of those stimuli-responsive nanomaterials in ferroptosis. Here, we describe the physiological feature of ferroptosis and illustrate the current challenges to induce ferroptosis for cancer therapy. Then, nanomaterials that induce ferroptosis are classified and elaborated according to the external and internal stimuli. Finally, the future perspectives in the field are proposed. We hope this review facilitates paving the way for the design of intelligent nano-ferroptosis inducers.

Innovative strategies for photodynamic therapy against hypoxic tumor

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

A hybrid metal-organic framework nanomedicine-mediated photodynamic therapy and hypoxia-activated cancer chemotherapy

The hypoxic tumor microenvironment and photodynamic therapy (PDT)-aggravated hypoxia compromise the anticancer efficacy of chemotherapy, immunotherapy, and PDT. Thus, sophisticated nanomedicines that can activate their anticancer capability in situ in response to specific stimuli need to be developed. This study aimed to construct a hybrid nanomedicine that activated chemotherapy by inducing hypoxia, which synergized with PDT to promote antitumor outcomes, contrary to the strategies focusing on reversing tumor hypoxia. The hybridization of a porphyrin metal-organic framework (MOF) and gold nanoparticles (AuNPs) enhanced the stability of the hybrid nanomedicine against the phosphate in blood, thereby preventing the premature drug release during blood circulation. The surface modification with polyethylene glycol (PEG) markedly increased the tumor accumulation of the hybrid MOF nanomedicine, which encapsulated a hypoxia-activated prodrug (tirapazamine, TPZ), by enhancing its colloidal stability and pharmacokinetics. The loaded TPZ was rapidly released from the nanomedicine in response to the concentrated intracellular phosphate after cellular uptake, and was then converted into a potent anticancer drug in a hypoxic microenvironment exacerbated by continuous O2 consumption during PDT. In vitro and in vivo experiments demonstrated that the synergistic PDT and hypoxia-activated chemotherapy exhibited enhanced antitumor therapeutic efficiency and superior antimetastatic effect, and effectively ablated the tumor without recurrence. Therefore, the sophisticated nanomedicine reported here, which eliminated cancer cells by inducing a hypoxic tumor microenvironment, showed translational potential in future therapeutic development.