Hydrogen Peroxide Responsive Iron-Based Nanoplatform for Multimodal Imaging-Guided Cancer Therapy

A pH-Responsive Drug-Delivery System Based on Apatinib-Loaded Metal-Organic Frameworks for Ferroptosis-Targeted Synergistic Anti-Tumor Therapy

Purpose

The efficacy of systemic therapy for hepatocellular carcinoma (HCC) is limited mainly by the complex tumor defense mechanism and the severe toxic side-effects of drugs. The efficacy of apatinib (Apa), a key liver cancer treatment, is unsatisfactory due to inadequate targeting and is accompanied by notable side-effects. Leveraging nanomaterials to enhance its targeting represents a crucial strategy for improving the effectiveness of liver cancer therapy.

Patients and Methods

A metal polyphenol network-coated apatinib-loaded metal-organic framework-based multifunctional drug-delivery system (MIL-100@Apa@MPN) was prepared by using metal-organic frameworks (MOFs) as carriers. The nanoparticles (NPs) were subsequently characterized using techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), zeta potential measurements, and particle size analysis. In vitro experiments were conducted to observe the drug release kinetics and cytotoxic effects of MIL-100@Apa@MPN on HepG2 cells. The in vivo anti-tumor efficacy of MIL-100@Apa@MPN was evaluated using the H22 tumor-bearing mouse model.

Results

The formulated MIL-100@Apa@MPN demonstrates remarkable thermal stability and possesses a uniform structure, with measured drug-loading (DL) and encapsulation efficiency (EE) rates of 28.33% and 85.01%, respectively. In vitro studies demonstrated that HepG2 cells efficiently uptake coumarin-6-loaded NPs, and a significant increase in cumulative drug release was observed under lower pH conditions (pH 5.0), leading to the release of approximately 73.72% of Apa. In HepG2 cells, MIL-100@Apa@MPN exhibited more significant antiproliferative activity compared to free Apa. In vivo, MIL-100@Apa@MPN significantly inhibited tumor growth, attenuated side-effects, and enhanced therapeutic effects in H22 tumor-bearing mice compared to other groups.

Conclusion

We have successfully constructed a MOF delivery system with excellent safety, sustained-release capability, pH-targeting, and improved anti-tumor efficacy, highlighting its potential as a therapeutic approach for the treatment of HCC.

Biomedical applications of stimuli-responsive nanomaterials

Nanomaterials have aroused great interests in drug delivery due to their nanoscale structure, facile modifiability, and multifunctional physicochemical properties. Currently, stimuli-responsive nanomaterials that can respond to endogenous or exogenous stimulus display strong potentials in biomedical applications. In comparison with conventional nanomaterials, stimuli-responsive nanomaterials can improve therapeutic efficiency and reduce the toxicity of drugs toward normal tissues through specific targeting and on-demand drug release at pathological sites. In this review, we summarize the responsive mechanism of a variety of stimulus, including pH, redox, and enzymes within pathological microenvironment, as well as exogenous stimulus such as thermal effect, magnetic field, light, and ultrasound. After that, biomedical applications (e.g., drug delivery, imaging, and theranostics) of stimuli-responsive nanomaterials in a diverse array of common diseases, including cardiovascular diseases, cancer, neurological disorders, inflammation, and bacterial infection, are presented and discussed. Finally, the remaining challenges and outlooks of future research directions for the biomedical applications of stimuli-responsive nanomaterials are also discussed. We hope that this review can provide valuable guidance for developing stimuli-responsive nanomaterials and accelerate their biomedical applications in diseases diagnosis and treatment.

A bimodal time-gated luminescence-magnetic resonance imaging nanoprobe based on a europium(III) complex anchored on BSA-coated MnO2 nanosheets for highly selective detection of H2O2

A novel nanocomposite, [Eu(BTD)3(DPBT)]-BSA@MnO2, is reported to serve as an effective nanoprobe for bimodal time-gated luminescence (TGL) and magnetic resonance (MR) imaging of H2O2in vitro and in vivo. The nanoprobe was fabricated by immobilizing visible-light-excitable Eu3+ complexes in bovine serum albumin (BSA)-coated lamellar MnO2 nanosheets. The TGL of the Eu3+ complex was effectively quenched by the MnO2 nanosheets. Upon exposure to H2O2, the MnO2 nanosheets underwent reduction to Mn2+, which simultaneously triggered rapid, selective and sensitive "turn-on" responses toward H2O2 in both TGL and MR detection modes. The presence of a protective "corona" formed by BSA enables the nanoprobe to withstand high concentrations of glutathione (GSH), a strong reducing agent of MnO2 nanosheets. This capability allows the nanoprobe to be utilized for detecting H2O2 in living biosamples. The combined utilization of TGL and MR detection modes enables the nanoprobe to image H2O2 across a wide range of resolutions, from the subcellular level to the whole body, without any depth limitations. The results obtained from these modes can be cross-validated, enhancing the accuracy of the detection. The capability of the nanoprobe was validated by TGL imaging of endogenous and exogenous H2O2 in live HeLa cells, as well as bimodal TGL-MR imaging of H2O2 in tumor-bearing mice. The research achievements suggest that the integration of luminescent lanthanide complexes with protein-coated MnO2 nanosheets offers a promising bimodal TGL-MR sensing platform for H2O2in vitro and in vivo.

Multi-Bioinspired MOF Delivery Systems from Microfluidics for Tumor Multimodal Therapy

Metal-organic framework (MOF)-based drug delivery systems have demonstrated values in oncotherapy. Current research endeavors are centralized on the functionality enrichment of featured MOF materials with designed versatility for synergistic multimodal treatments. Here, inspired by the multifarious biological functions including ferroptosis pattern, porphyrins, and cancer cell membrane (CCM) camouflage technique, novel multi-biomimetic MOF nanocarriers from microfluidics are prepared. The Fe3+ , meso-tetra(4-carboxyphenyl)porphine and oxaliplatin prodrug are incorporated into one MOF nano-system (named FeTPt), which is further cloaked by CCM to obtain a "Trojan Horse"-like vehicle (FeTPt@CCM). Owing to the functionalization with CCM, FeTPt@CCM can target and accumulate at the tumor site via homologous binding. After being internalized by cancer cells, FeTPt@CCM can be activated by a Fenton-like reaction as well as a redox reaction between Fe3+ and glutathione and hydrogen peroxide to generate hydroxyl radical and oxygen. Thus, the nano-platform effectively initiates ferroptosis and improves photodynamic therapy performance. Along with the Pt-drug chemotherapy, the nano-platform exhibits synergistic multimodal actions for inhibiting cancer cell proliferation in vitro and suppressing tumor growth in vivo. These features indicate that such a versatile biomimetic MOF delivery system from microfluidics has great potential for synergistic cancer treatment.

Multifunctional polysaccharide nanoprobes for biological imaging

Imaging and tracking biological targets or processes play an important role in revealing molecular mechanisms and disease states. Bioimaging via optical, nuclear, or magnetic resonance techniques enables high resolution, high sensitivity, and high depth imaging from the whole animal down to single cells via advanced functional nanoprobes. To overcome the limitations of single-modality imaging, multimodality nanoprobes have been engineered with a variety of imaging modalities and functionalities. Polysaccharides are sugar-containing bioactive polymers with superior biocompatibility, biodegradability, and solubility. The combination of polysaccharides with single or multiple contrast agents facilitates the development of novel nanoprobes with enhanced functions for biological imaging. Nanoprobes constructed with clinically applicable polysaccharides and contrast agents hold great potential for clinical translations. This review briefly introduces the basics of different imaging modalities and polysaccharides, then summarizes the recent progress of polysaccharide-based nanoprobes for biological imaging in various diseases, emphasizing bioimaging with optical, nuclear, and magnetic resonance techniques. The current issues and future directions regarding the development and applications of polysaccharide nanoprobes are further discussed.

Three Strategies in Engineering Nanomedicines for Tumor Microenvironment-Enabled Phototherapy

Canonical phototherapeutics have several limitations, including a lack of tumor selectivity, nondiscriminatory phototoxicity, and tumor hypoxia aggravation. The tumor microenvironment (TME) is characterized by hypoxia, acidic pH, and high levels of H2 O2 , GSH, and proteases. To overcome the shortcomings of canonical phototherapy and achieve optimal theranostic effects with minimal side effects, unique TME characteristics are employed in the development of phototherapeutic nanomedicines. In this review, the effectiveness of three strategies for developing advanced phototherapeutics based on various TME characteristics is examined. The first strategy involves targeted delivery of phototherapeutics to tumors with the assistance of TME-induced nanoparticle disassembly or surface modification. The second strategy involves near-infrared absorption increase-induced phototherapy activation triggered by TME factors. The third strategy involves enhancing therapeutic efficacy by ameliorating TME. The functionalities, working principles, and significance of the three strategies for various applications are highlighted. Finally, possible challenges and future perspectives for further development are discussed.

Usnea Acid-Incorporated Ca2+ /Mn2+ Ions Reservoirs for Elevated Ion-Interference Therapy through Synergetic Biocatalysis and Osmolarity Imbalance

Ion-interference therapy (IIT) utilizes ions to disturb intracellular biological processes and has been received increasing attention in tumor treatments recently. However, the low therapeutic efficiency still hinders its further biological applications. Herein, via a simple and one-pot gas diffusion process, polyethylene glycol (PEG)-modified Mn2+ ions and usnic acid (UA)-incorporated CaCO3 nanomaterials (PEG CaMnUA) as Ca2+ /Mn2+ ions reservoirs are prepared for magnetic resonance imaging (MRI)-guided UA-elevated IIT. Among PEG CaMnUA, UA not only increases cytoplasmic Ca2+ ions to amplify Ca2+ overload caused by CaCO3 decomposition, but also enhances Mn2+ ions-participated Fenton-like biocatalysis by intracellular H2 O2 generation and glutathione consumption. Then increasing the intracellular oxidative stress and decreasing the triphosadenine supply induce apoptosis together, resulting in UA-boosted IIT. The simple and efficient design of the dual ions reservoirs will contribute to improve the antitumor activity of IIT and further development of calcium-based nanomaterials in the future.

Tirapazamine-loaded UiO-66/Cu for ultrasound-mediated promotion of chemodynamic therapy cascade hypoxia-activated anticancer therapy

Chemodynamic therapy (CDT), an emerging oncology treatment, has received considerable attention owing to its high selectivity, less aggressiveness, and endogenous stimulation. However, the complex intra-tumor environment limits the therapeutic effect. In this study, Cu⁺ was directly doped into the structure of the UiO-66 matrix using an in situ one-pot oil bath method. The as-formed UiO-66/Cu possessed a large surface area, making it feasible to modify folic acid (FA) and carry more chemotherapeutic agents like tirapazamine (TPZ), thus forming UiO-66/Cu-FA-TPZ nanoplatforms. For CDT, the nanoplatform catalyzed the cyclic generation of the highly oxidizing hydroxyl radical (·OH) from H₂O₂. Particularly, low-frequency ultrasound enhanced the curative effect. Notably, in a tumor, a severe hypoxic environment and ultrasound can activate more TPZ for safe and efficient chemotherapy, achieving synergistic and hypoxia-activated tumor treatment with a low risk of side effects. Moreover, the nanoplatform exhibits computed tomography imaging functions for combined diagnosis and treatment. Our designed nanoplatform overcomes the dilemma of insufficient efficacy from conventional therapy attributed to a hypoxic environment, expecting to guide the design of future treatment regimens for hypoxic tumors.

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

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

Laser-Induced Combinatorial Chemotherapeutic, Chemodynamic, and Photothermal Therapy for Hepatocellular Carcinoma Based on Oxaliplatin-Loaded Metal-Organic Frameworks

The activation of nanoparticles (NPs) in the tumor microenvironment exerts synergistic therapeutic effects with chemotherapy against multiple cancers. In this study, an NP system prepared using biocompatible MIL-100 NPs was studied as an effective vehicle to deliver oxaliplatin for hepatocellular carcinoma treatment. The NPs were coated with polydopamine (PDA) and NH₂-PEGTK-COOH and then loaded with oxaliplatin to create the multi-functional NP Oxa@MIL-PDA-PEGTK. Oxa@MIL-PDA-PEGTK is activated in the tumor microenvironment, causing the generation of cytotoxic reactive oxygen species (ROS) via the Fenton reaction and the release of the loaded oxaliplatin. In addition, under near-infrared (NIR) irradiation, Oxa@MIL-PDA-PEGTK can generate hyperthermia at tumor sites. Moreover, owing to the light-induced activation of the Oxa@MIL-PDA-PEGTK NPs, higher drug delivery efficiency, more precise targeted activation, and reduced off-target toxicity were observed in in vitro and in vivo experiments. Taken together, owing to its improved drug delivery efficiency and multi-functional activities, including the ability for targeted chemotherapy coupled with photothermal and chemodynamic therapy, Oxa@MIL-PDA-PEGTK may serve as a new approach for treating hepatocellular carcinoma.

Enhanced Bactericidal Effect of Calcinated Mg-Fe Layered Double Hydroxide Films Driven by the Fenton Reaction

Osteogenic and antibacterial abilities are the permanent pursuit of titanium (Ti)-based orthopedic implants. However, it is difficult to strike the right balance between these two properties. It has been proved that an appropriate alkaline microenvironment formed by Ti modified by magnesium-aluminum layered double hydroxides (Mg-Al LDHs) could achieve the selective killing of bacteria and promote osteogenesis. However, the existence of Al induces biosafety concerns. In this study, iron (Fe), an essential trace element in the human body, was used to substitute Al, and a calcinated Mg-Fe LDH film was constructed on Ti. The results showed that a proper local alkaline environment created by the constructed film could enhance the antibacterial and osteogenic properties of the material. In addition, the introduction of Fe promoted the Fenton reaction and could produce reactive oxygen species in the infection environment, which might further strengthen the in vivo bactericidal effect.

Multifunctional phototheranostic agent ZnO@Ag for anti-infection through photothermal/photodynamic therapy

To overcome the limitations of traditional therapeutics, nanotechnology offers a synergistic therapeutic approach for the treatment of bacterial infection and biofilms that has attracted attention. Herein, we report on a ZnO@Ag nanocomposite with good biocompatibility synthesized by doping ZnO NPs with silver nanoparticles (Ag NPs). ZnO@Ag nanocomposites were synthesized with varying ratios of Ag NPs (0.5%, 2%, 8%). Under the same experimental conditions, ZnO@8%Ag exhibited outstanding properties compared to the other nanocomposites and the pristine ZnO NPs. ZnO@8%Ag demonstrated excellent photothermal and photodynamic properties. Also, ZnO@8%Ag demonstrated over 99% inhibition of Staphylococcus aureus (S. aureus) under photothermal therapy (PTT) or photodynamics therapy (PDT) as a result of the excessive generation of reactive oxygen species (ROS) by the Ag+ released, while the pristine ZnO showed an insignificant inhibition rate compared to the PBS group (control). Furthermore, ZnO@8%Ag completely disrupted S. aureus biofilm under a combined PTT/PDT treatment, a synergetic trimodal therapy, although the molecular mechanism of biofilm inhibition remains unclear. Hence, the excellent photothermal, photodynamic, biocompatibility, and bactericidal properties of ZnO@8%Ag present it as an appropriate platform for bacterial and biofilm treatment or other biomedically related applications.

Nanotrains of DNA Copper Nanoclusters That Triggered a Cascade Fenton-Like Reaction and Glutathione Depletion to Doubly Enhance Chemodynamic Therapy

Many current chemodynamic therapy (CDT) strategies suffer from either low therapeutic efficiency or the deficiency of poor targeting. The low therapeutic efficiency is mainly ascribed to the intracellular antioxidant system and the inefficient Fenton reaction in the weakly acidic tumor microenvironment (TME). Herein, by exploitation of the diverse function and programmability of functional nucleic acid, aptamer-tethered nanotrains of DNA copper nanoclusters (aptNTDNA-CuNCs) were assembled to simultaneously achieve targeted recognition, loading, and delivery of CDT reagents into tumor cells without an external carrier. The intracellular hydrogen peroxide (H₂O₂) oxidized nanotrains of DNA-CuNCs to produce a lot of Cu²⁺ and Cu⁺ ions, which can generate reactive oxygen species (ROS) in the weakly acidic TME based on the pH-independent Fenton-like reaction of Cu⁺/H₂O₂. Meanwhile, the redox reaction between intracellular glutathione (GSH) and Cu²⁺ depleted GSH and generated Cu⁺ ions, which weakened the antioxidant ability of cancer cells and further enhanced the Fenton-like reaction of Cu⁺/H₂O₂, respectively. Thus, the cascade Fenton-like reaction and GSH depletion doubly improved the efficacy of CDT. The in vivo and in vitro study solidly confirmed that aptNTDNA-CuNCs have excellent antitumor efficacy and no cytotoxicity to healthy cells. Therefore, aptNTDNA-CuNCs can act as CDT reagents to achieve highly efficient, biocompatible, and targeted CDT.

Recent Advances in Near-Infrared-II Fluorescence Imaging for Deep-Tissue Molecular Analysis and Cancer Diagnosis

Fluorescence imaging with high sensitivity and minimal invasiveness has received tremendous attention, which can accomplish visualized monitoring and evaluation of cancer progression. Compared with the conventional first near-infrared (NIR-I) optical window (650-950 nm), fluorescence imaging in the second NIR optical window (NIR-II, 950-1700 nm) exhibits deeper tissue penetration capability and higher temporal-spatial resolution with lower background interference for achieving deep-tissue in vivo imaging and real-time monitoring of cancer development. Encouraged by the significant preponderances, a variety of multifunctional NIR-II fluorophores have been designed and fabricated for sensitively imaging biomarkers in vivo and visualizing the treatment procedure of cancers. In this review, the differences between NIR-I and NIR-II fluorescence imaging are briefly introduced, especially the advantages of NIR-II fluorescence imaging for the real-time visualization of tumors in vivo and cancer diagnosis. An important focus is to summarize the NIR-II fluorescence imaging for deep-tissue biomarker analysis in vivo and tumor tissue visualization, and a brief introduction of NIR-II fluorescence imaging-guided cancer therapy is also presented. Finally, the significant challenges and reasonable prospects of NIR-II fluorescence imaging for cancer diagnosis in clinical applications are outlined.

Recent advances in engineering iron oxide nanoparticles for effective magnetic resonance imaging

Iron oxide nanoparticle (IONP) with unique magnetic property and high biocompatibility have been widely used as magnetic resonance imaging (MRI) contrast agent (CA) for long time. However, a review which comprehensively summarizes the recent development of IONP as traditional T₂ CA and its new application for different modality of MRI, such as T₁ imaging, simultaneous T₂/T₁ or MRI/other imaging modality, and as environment responsive CA is rare. This review starts with an investigation of direction on the development of high-performance MRI CA in both T₂ and T₁ modal based on quantum mechanical outer sphere and Solomon–Bloembergen–Morgan (SBM) theory. Recent rational attempts to increase the MRI contrast of IONP by adjusting the key parameters, including magnetization, size, effective radius, inhomogeneity of surrounding generated magnetic field, crystal phase, coordination number of water, electronic relaxation time, and surface modification are summarized. Besides the strategies to improve r₂ or r₁ values, strategies to increase the in vivo contrast efficiency of IONP have been reviewed from three different aspects, those are introducing second imaging modality to increase the imaging accuracy, endowing IONP with environment response capacity to elevate the signal difference between lesion and normal tissue, and optimizing the interface structure to improve the accumulation amount of IONP in lesion. This detailed review provides a deep understanding of recent researches on the development of high-performance IONP based MRI CAs. It is hoped to trigger deep thinking for design of next generation MRI CAs for early and accurate diagnosis.

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T₂ contrast capacity of iron oxide nanoparticles (IONPs) could be improved based on quantum mechanical outer sphere theory.

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IONPs could be expand to be used as effective T₁ CAs by improving q value, extending τ_s, and optimizing interface structure.

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Environment responsive MRI CAs have been developed to improve the diagnosis accuracy.

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Introducing other imaging contrast moiety into IONPs could increase the contrast efficiency.

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Optimizing in vivo behavior of IONPs have been proved to enlarge the signal difference between normal tissue and lesion.

Tumor microenvironment-responsive versatile "Trojan horse" theranostic nanoplatform for magnetic resonance imaging-guided multimodal synergistic antitumor treatment

A natural killer (NK)-92 cell membrane-camouflaged mesoporous MnO₂-enveloped Au@Pd (Au@Pd@MnO₂) nanoparticles (denoted as APMN NPs)-based versatile biomimetic theranostic nanoplatform was developed for magnetic resonance (MR) imaging-guided multimodal synergistic antitumor treatments. In this core-shell nanostructure, an Au@Pd core induced near-infrared (NIR)-activatable hyperthermal effects and nanozyme catalytic activity, while a mesoporous MnO₂ shell not only afforded a high drug-loading capability, tumor microenvironment (TME)-triggered MR imaging and drug release, but also endowed catalase-, glutathione peroxidase-, and Fenton-like activities. Furthermore, the NK-92 cell membrane camouflaging endowed the NPs with enhanced tumor-targeting capability, immune escape function, and membrane protein-mediated tumoral uptake property. The doxorubicin-loaded APMN (D-APMN) NPs exhibited TME-responsive drug release properties. Furthermore, the cellular uptake, in vivo MR imaging, and NIR thermal imaging confirmed the active tumor-targeting capability and TME-responsive MR imaging property of these biomimetic NPs. An antitumor efficacy test, histological analyses, and blood biochemical profiles suggested that the developed D-APMN NPs possessed a high antitumor activity and biosafety in tumor-bearing nude mice. Therefore, the developed APMN NPs held great potential as an intelligent and comprehensive theranostic nanoplatform for tumor-specific bioimaging and TME-responsive multimodality treatment based on photothermal therapy, chemodynamic therapy, and chemotherapy. STATEMENT OF SIGNIFICANCE: Exploring intelligent and comprehensive theranostic nanoplatforms to integrate tumor-specific bioimaging and TME-responsive multimodal therapy effectively is a challenge. Herein, we successfully developed a new kind of NK-92 cell membrane-camouflaged mesoporous MnO₂-enveloped Au@Pd nanoparticles (APMN NPs)-based versatile biomimetic theranostic nanoplatform for the potential MR imaging-guided multimodal synergistic antitumor treatments. These NPs could integrate unique structural, optical, multiple-catalytic, paramagnetic, and biological merits of NK-92 cell membrane, Au@Pd cores and mesoporous MnO₂ shell in a single nanoplatform. The NK-92 cell membrane camouflaging endowed the NPs with enhanced tumor-targeting capability, immune escape function, and membrane protein-mediated tumoral uptake property. The new information obtained from this study may be beneficial to promote the development of novel TME-responsive versatile "Trojan horse" theranostic nanoplatforms for efficient MR imaging-guided multimodal synergistic treatment.

Smart nanomaterials for cancer diagnosis and treatment

Innovations in nanomedicine has guided the improved outcomes for cancer diagnosis and therapy. However, frequent use of nanomaterials remains challenging due to specific limitations like non-targeted distribution causing low signal-to-noise ratio for diagnostics, complex fabrication, reduced-biocompatibility, decreased photostability, and systemic toxicity of nanomaterials within the body. Thus, better nanomaterial-systems with controlled physicochemical and biological properties, form the need of the hour. In this context, smart nanomaterials serve as promising solution, as they can be activated under specific exogenous or endogenous stimuli such as pH, temperature, enzymes, or a particular biological molecule. The properties of smart nanomaterials make them ideal candidates for various applications like biosensors, controlled drug release, and treatment of various diseases. Recently, smart nanomaterial-based cancer theranostic approaches have been developed, and they are displaying better selectivity and sensitivity with reduced side-effects in comparison to conventional methods. In cancer therapy, the smart nanomaterials-system only activates in response to tumor microenvironment (TME) and remains in deactivated state in normal cells, which further reduces the side-effects and systemic toxicities. Thus, the present review aims to describe the stimulus-based classification of smart nanomaterials, tumor microenvironment-responsive behaviour, and their up-to-date applications in cancer theranostics. Besides, present review addresses the development of various smart nanomaterials and their advantages for diagnosing and treating cancer. Here, we also discuss about the drug targeting and sustained drug release from nanocarriers, and different types of nanomaterials which have been engineered for this intent. Additionally, the present challenges and prospects of nanomaterials in effective cancer diagnosis and therapeutics have been discussed.

Fabrication of pH/H2O2-responsive polyhedral oligomeric silsesquioxane self-assembled fluorescent vesicles for enhanced in vivo anti-tumor efficacy

Aim: The rational design of a fluorescence imaging-guided, highly efficient multiresponsive delivery system is important for improving drug delivery efficiency. Materials and methods: Herein, pH/H₂O₂-responsive polyhedral oligomeric silsesquioxane (POSS) molecule functionalized 4-(phenyl(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)amino)benzaldehyde (OTB) copolymer (PEG-POSS-OTB) was synthesized to encapsulate doxorubicin (DOX) for precise drug delivery. Results: The self-assembly fluorescent vesicles exhibited excellent pH/H₂O₂-responsive drug release properties under physiological conditions and efficient drug-targeting ability. In vitro, compared with the DOX group, PEG-POSS-OTB fluorescent vesicles exhibited improved drug delivery and reduced toxicity. Importantly, we performed a proof-of-concept study demonstrating that PEG-POSS-OTB fluorescent vesicles were a high-efficiency nanoassembly drug-delivery platform for improving drug delivery efficiency. In vivo studies demonstrated that PEG-POSS-OTB vesicles with enhanced stability could be used in targeted drug delivery and controlled intelligent release.

2D material-based peroxidase-mimicking nanozymes: catalytic mechanisms and bioapplications

The boom in nanotechnology brings new insights into the development of artificial enzymes (nanozymes) with ease of modification, lower manufacturing cost, and higher catalytic stability than natural enzymes. Among various nanomaterials, two-dimensional (2D) nanomaterials exhibit promising enzyme-like properties for a plethora of bioapplications owing to their unique physicochemical characteristics of tuneable composition, ultrathin thickness, and huge specific surface area. Herein, we review the recent advances in several 2D material-based nanozymes, such as carbonaceous nanosheets, metal-organic frameworks (MOFs), transition metal dichalcogenides (TMDs), layered double hydroxides (LDHs), and transition metal oxides (TMOs), clarify the mechanisms of peroxidase (POD)-mimicking catalytic behaviors, and overview the potential bioapplications of 2D nanozymes.

Design of Magnetic Nanoplatforms for Cancer Theranostics

Cancer is the top cause of death globally. Developing smart nanomedicines that are capable of diagnosis and therapy (theranostics) in one-nanoparticle systems are highly desirable for improving cancer treatment outcomes. The magnetic nanoplatforms are the ideal system for cancer theranostics, because of their diverse physiochemical properties and biological effects. In particular, a biocompatible iron oxide nanoparticle based magnetic nanoplatform can exhibit multiple magnetic-responsive behaviors under an external magnetic field and realize the integration of diagnosis (magnetic resonance imaging, ultrasonic imaging, photoacoustic imaging, etc.) and therapy (magnetic hyperthermia, photothermal therapy, controlled drug delivery and release, etc.) in vivo. Furthermore, due to considerable variation among tumors and individual patients, it is a requirement to design iron oxide nanoplatforms by the coordination of diverse functionalities for efficient and individualized theranostics. In this article, we will present an up-to-date overview on iron oxide nanoplatforms, including both iron oxide nanomaterials and those that can respond to an externally applied magnetic field, with an emphasis on their applications in cancer theranostics.

Co-delivery of dihydroartemisinin and pyropheophorbide-iron elicits ferroptosis to potentiate cancer immunotherapy

Dihydroartemisinin (DHA) has shown cytotoxicity against various tumor cells in vitro in an iron-dependent manner, but its in vivo antitumor efficacy is compromised by its rapid degradation and clearance. Here we show the induction of ferroptosis by DHA in an immunogenic fashion and the maximization of in vivo antitumor efficacy of DHA by co-delivering a cholesterol derivative of DHA (Chol-DHA) and Pyropheophorbide-iron (Pyro-Fe) in ZnP@DHA/Pyro-Fe core-shell nanoparticles. ZnP@DHA/Pyro-Fe particles stabilize DHA against hydrolysis and prolong blood circulation of Chol-DHA and Pyro-Fe for their enhanced uptake in tumors. Co-delivery of an exogenous iron complex and DHA induces more ROS production and causes significant tumor inhibition in vivo. By increasing tumor immunogenicity, the combination of DHA and Pyro-Fe sensitizes non-immunogenic colorectal tumors to anti-PD-L1 checkpoint blockade immunotherapy. These findings suggest the potential of using nanotechnology to repurpose DHA and other drugs with excellent safety profiles for combination with immune checkpoint blockade to treat cancers.

Acidic microenvironment responsive polymeric MOF-based nanoparticles induce immunogenic cell death for combined cancer therapy

BACKGROUND

The complex tumor microenvironment and non-targeting drugs limit the efficacy of clinical tumor therapy. For ensuring the accurate delivery and maximal effects of anticancer drugs, it is important to develop innovative drug delivery system based on nano-strategies.

RESULT

In this study, an intracellular acidity-responsive polymeric metal organic framework nanoparticle (denoted as DIMP) has been constructed, which can co-deliver the chemotherapy agent of doxorubicin (DOX) and phototherapy agent of indocyanine green (ICG) for breast carcinoma theranostics. Specifically, DIMP possesses a suitable and stable nanometer size and can respond to the acidic microenvironment in cells, thus precisely delivering drugs into target tumor sites and igniting the biological reactions towards cell apoptosis. Following in vivo and in vitro results showed that DIMP could be effectively accumulated in tumor sites and induced powerful immunogenic cell death (ICD) effect.

CONCLUSION

The designed DIMP displayed its effectiveness in combined photo-chemotherapy with auxiliary of ICD effect under a multimodal imaging monitor. Thus, the present MOF-based strategy may offer a potential paradigm for designing drug-delivery system for image-guided synergistic tumor therapy.

Tumor Microenvironment Responsive Single-Atom Nanozymes for Enhanced Antitumor Therapy

Single-atom nanozymes (SAzymes) with specific response to the unique tumor microenvironment (TME) feature providing 100% metal atoms utilization for high-efficient enzyme-catalyzed therapy and accurate template for the study of therapeutic mechanisms. In this review, we first introduce the various synthetic strategies of SAzymes, and the TME-responsive SAzymes activities. Next, the TME-responsive enhanced antitumor therapeutic approaches based on the enzymatic activities of SAzymes are summarized, and the corresponding therapy mechanisms are elaborated. Subsequently, a concise but concentrated summary, and the challenges and opportunities for the future design and engineering of SAzyme are outlined. As a newly-built discipline, SAzymes have vast space for development in enhanced antitumor therapy. This timely review provides guidance and constructive suggestions for the future of SAzymes.

Nanomedicine in Pancreatic Cancer: Current Status and Future Opportunities for Overcoming Therapy Resistance

Simple Summary

Despite access to a vast arsenal of anticancer agents, many fail to realise their full therapeutic potential in clinical practice. One key determinant of this is the evolution of multifaceted resistance mechanisms within the tumour that may either pre-exist or develop during the course of therapy. This is particularly evident in pancreatic cancer, where limited responses to treatment underlie dismal survival rates, highlighting the urgent need for new therapeutic approaches. Here, we discuss the major features of pancreatic tumours that contribute to therapy resistance, and how they may be alleviated through exploitation of the mounting and exciting promise of nanomedicines; a unique collection of nanoscale platforms with tunable and multifunctional capabilities that have already elicited a widespread impact on cancer management.

Abstract

The development of drug resistance remains one of the greatest clinical oncology challenges that can radically dampen the prospect of achieving complete and durable tumour control. Efforts to mitigate drug resistance are therefore of utmost importance, and nanotechnology is rapidly emerging for its potential to overcome such issues. Studies have showcased the ability of nanomedicines to bypass drug efflux pumps, counteract immune suppression, serve as radioenhancers, correct metabolic disturbances and elicit numerous other effects that collectively alleviate various mechanisms of tumour resistance. Much of this progress can be attributed to the remarkable benefits that nanoparticles offer as drug delivery vehicles, such as improvements in pharmacokinetics, protection against degradation and spatiotemporally controlled release kinetics. These attributes provide scope for precision targeting of drugs to tumours that can enhance sensitivity to treatment and have formed the basis for the successful clinical translation of multiple nanoformulations to date. In this review, we focus on the longstanding reputation of pancreatic cancer as one of the most difficult-to-treat malignancies where resistance plays a dominant role in therapy failure. We outline the mechanisms that contribute to the treatment-refractory nature of these tumours, and how they may be effectively addressed by harnessing the unique capabilities of nanomedicines. Moreover, we include a brief perspective on the likely future direction of nanotechnology in pancreatic cancer, discussing how efforts to develop multidrug formulations will guide the field further towards a therapeutic solution for these highly intractable tumours.

Nanomagnet-facilitated pharmaco-compatibility for cancer diagnostics: Underlying risks and the emergence of ultrasmall nanomagnets

Cancer therapy is a fast-emerging biomedical paradigm that elevates the diagnostic and therapeutic potential of a nanovector for identification, monitoring, targeting, and post-treatment response analysis. Nanovectors of superparamagnetic iron oxide nanoparticles (SPION) are of tremendous significance in cancer therapy because of their inherited high surface area, high reactivity, biocompatibility, superior contrast, and magnetic and photo-inducibility properties. In addition to a brief introduction, we summarize various progressive aspects of nanomagnets pertaining to their production with an emphasis on sustainable biomimetic approaches. Post-synthesis particulate and surface alterations in terms of pharmaco-affinity, liquid accessibility, and biocompatibility to facilitate cancer therapy are highlighted. SPION parameters including particle contrast, core-fusions, surface area, reactivity, photosensitivity, photodynamics, and photothermal properties, which facilitate diverse cancer diagnostics, are discussed. We also elaborate on the concept of magnetism to selectively focus chemotherapeutics on tumors, cell sorting, purification of bioentities, and elimination of toxins. Finally, while addressing the toxicity of nanomaterials, the advent of ultrasmall nanomagnets as a healthier alternative with superior properties and compatible cellular interactions is reviewed. In summary, these discussions spotlight the versatility and integration of multi-tasking nanomagnets and ultrasmall nanomagnets for diverse cancer theragnostics.

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SPION synthesis with ascribed prominence on sustainable procedures.

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Particulate species, composition, and surface alteration-enabled theragnostics are highlighted.

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Inherent properties of SPIONs facilitating cancer diagnostics are elaborated.

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Magnetism-based “chemotherapeutics,” cell-sorting, and bioentity purification are emphasized.

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Emergence of ultrasmall SPIONs as a healthier option is summarized.

Nano-photosensitizers for enhanced photodynamic therapy

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

Catalase Nanocrystals Loaded with Methylene Blue as Oxygen Self-Supplied, Imaging-Guided Platform for Photodynamic Therapy of Hypoxic Tumors

Photodynamic therapy (PDT) is a well-known method for cancer therapy in the clinic. However, the inherent hypoxia microenvironment of solid tumors enormously restricts the PDT efficiency. Herein, catalase nanocrystals (CatCry) are introduced as in situ oxygen (O₂ )-generating system to relieve tumor hypoxia and enhance PDT efficiency for solid tumors. After loading with photosensitizer methylene blue (MB), a PDT drug platform (CatCry-MB) emerges, allowing for significant increasing PDT efficiency instigated by three factors. First, the high stability and recyclable catalytic activity of CatCry enable a long-term endogenous H₂ O₂ decomposition for continuous O₂ supply for sustained relief of tumor hypoxia. Second, both the produced O₂ and loaded MB are confined within CatCry nanoporous structure, shortening the diffusion distance between O₂ and MB to maximize the production of singlet oxygen (¹ O₂ ). Third, the MB molecules are uniformly dispersed within CatCry lattice, avoiding MB aggregation and causing more MB molecules be activated to produce more ¹ O₂ . With the three complementary mechanisms, tumor hypoxia is eradicated and the resulted enhancement in PDT efficiency is demonstrated in vitro and in vivo. The proposed approach opens up a new venue for the development of other O₂ -dependent tumor treatments, such as chemotherapy, radiotherapy, and immunotherapy.

Recent Advances in Nanoparticle-Mediated Diagnosis and the Treatment of Pancreatic Cancer

Pancreatic cancer (PC), one of the most lethal solid tumors in humans, has a five-year survival rate of only 4%. Surgical treatment is the only accepted therapy with curative intent because the vast majority of these tumors are chemoresistant. Unfortunately, due to the aggressive nature of these tumors, fewer than 20% are resectable when the first symptoms occur. Novel therapies are required to overcome all these therapeutic issues, and the development of active nanocarriers represents an exciting opportunity to improve PC outcomes. The present review focuses on recent advances in the field of nanotechnology with application in PC treatment.

A covalent organic framework-based nanoagent for H2S-activable phototherapy against colon cancer

Herin, we report a Cu(ii)-porphyrin-derived nanoscale COF, which can be triggered by endogenous H₂S via an intracellular sulfidation reaction to generate a metal-free COF-photosensitizer for PDT against H₂S-enriched colon tumors with controllable singlet oxygen release; meanwhile in situ generated CuS can be synchronously used as a photothermal agent for PTT.

Hyaluronic acid-modified manganese dioxide-enveloped hollow copper sulfide nanoparticles as a multifunctional system for the co-delivery of chemotherapeutic drugs and photosensitizers for efficient synergistic antitumor treatments

This paper presents the design of a new type of intelligent and versatile all-in-one therapeutic nanoplatform for the co-delivery of chemotherapeutic drugs and photosensitizers to facilitate multimodal antitumor treatment; the system is based on hyaluronic acid (HA)-modified manganese dioxide (MnO₂)-enveloped hollow porous copper sulfide (CuS) nanoparticles (CuS@MnO₂/HA NPs). In this system, a CuS inner shell allows for the co-loading of doxorubicin (DOX) and indocyanine green (ICG) and induces photothermal effects, and a biodegradable MnO₂ external shell affords on-demand tumor microenvironment (TME)-triggered release and catalase- andFenton-like activities. Moreover, the HA modification endows the system with a CD44 receptor-mediated tumor-targeting property. The formulated DOX and ICG co-loaded CuS@MnO₂/HA (DOX/ICG-CuS@MnO₂/HA) NPs were found to exhibit excellent photothermal performance both in vitro and in vivo. In addition, DOX/ICG-CuS@MnO₂/HA NPs were found to display both TME and near-infrared (NIR)-responsive controlled release properties. The NPs also have a superior reactive oxygen species (ROS) generation capacity due to the combination of enhanced ICG-induced singlet oxygen and CuS@MnO₂-mediated hydroxyl radicals. The cellular uptake, fluorescence imaging property, cytotoxicity, and thermal imaging of these NPs were also evaluated. In tumor-bearing mice, the DOX/ICG-CuS@MnO₂/HA NPs displayeda superior antitumor efficacy (2.57-fold) as compared with free DOX. Therefore, the developed DOX/ICG-CuS@MnO₂/HA NPs have a great potential for use as an all-in-one nanotherapeutic agent for the efficient and precise induction of chemo/photothermal/photodynamic/chemodynamic therapy with superior antitumor efficacy and fewer side effects.

Biodegradable BiOCl platform for oxidative stress injury-enhanced chemodynamic/radiation therapy of hypoxic tumors

Various physiological characteristics of the tumor microenvironment (TME), such as hypoxia, overexpression of glutathione (GSH) and hydrogen peroxide (H₂O₂), and mild acidity, can severely reduce the efficacy of many cancer therapies. Altering the redox balance of the TME and increasing oxidative stress can accordingly enhance the efficacy of tumor therapy. Herein, we developed a bismuth-based Cu²⁺-doped BiOCl nanotherapeutic platform, BCHN, able to self-supply H₂O₂ for TME-regulated chemodynamic therapy (CDT) combined with sensitized radiotherapy (RT). BCHN released H₂O₂ and consumed GSH to degrade the composite in the slightly acidic TME, and generated hydroxyl radicals (•OH) via a Fenton-like reaction catalyzed by copper ions, to achieve oxidative stress-enhanced CDT. The Fenton-like reaction also catalyzed H₂O₂ to produce O₂ to relieve tumor hypoxia, and combined with the X-ray-blocking property of bismuth to realize TME-enhanced radiotherapy. Synergistic CDT/RT has previously been shown to effectively inhibit tumor cell proliferation and achieve effective tumor control. The current results demonstrated a highly efficient multifunctional bio-degradable nanoplatform for oncotherapy. STATEMENT OF SIGNIFICANCE: Tumor microenvironment-modulated synergy of radiotherapy and chemodynamic therapy is conducive to rapid tumor ablation. Based on this principle, we fabricated a biodegradable BiOCl-based nanocomposite, BCHN. By supplying H₂O₂, a Fenton-like reaction generated •OH and O₂ catalyzed by copper ions, and consumed glutathione to biodegrade the composite. Overall, these actions increased tumor oxidative stress and realized the synergistic anti-tumor actions of chemodynamic therapy combined with bismuth-based sensitization radiotherapy. This strategy thus provides a unique approach to oncology therapy.

Stimuli-activated molecular photothermal agents for cancer therapy

Taking advantage of activatable and imaging-guided properties, stimuli-activated molecular photothermal agents (MPTAs) have drawn great attention in photothermal therapy (PTT) over the past decades. In this review, the recent progress in the study of stimuli-activated MPTAs is summarized from different stimuli, including pH, bioactive small molecules, and enzymes. The features and challenges of stimuli-activated MPTAs are also discussed. This review aims to motivate readers to design and synthesise more efficient MPTAs.

Glucose oxidase loaded Cu2+ based metal-organic framework for glutathione depletion/reactive oxygen species elevation enhanced chemotherapy

INTRODUCTION

The development of multidrug resistance (MDR) is a major cause for the failure of chemotherapy, which requires the aid of nanomedicine.

METHODS

Here in our study, a Cu²⁺ based metal-organic framework (COF) was firstly developed and employed as a carrier for the delivery of glucose oxidase (GOx) and doxorubicin (Dox) (COF/GOx/Dox) for the therapy of MDR lung cancers.

RESULTS

Our results showed that the GOx can catalyze glucose and produce H₂O₂. In the mean time, the Cu²⁺ can react with GSH and then transform into Cu⁺, which resulted in GSH depletion. Afterwards, the produced Cu⁺ and H₂O₂ trigger Fenton reaction to generate ROS to damage the redox equilibrium of cancer cells. Both effects contributed to the reverse of MDR in A549/Dox cells and finally resulted in significantly enhanced in vitro/in vivo anticancer performance.

DISCUSSION

The combination of glutathione depletion/reactive oxygen species elevation might be a promising strategy to enhance the efficacy of chemotherapy and reverse MDR in cancers.

Photoluminescence with an unusual open-loop and rigid delocalized conjugated structure in quantum dots

It is well known that almost all photoluminescent molecules are aromatic or heterocyclic ring compounds for bioimaging analysis. A question remains as to whether a breakthrough can be achieved regarding a novel photoluminescent molecule without a ring structure, and in a what manner. In this study, we explored the photoelectric conversion and structure of photoluminescent compounds, and constructed an intra-molecular coupling positive-negative-junction (PNJ) with an open-loop and rigid Π₅⁶ delocalized conjugated structure of the coupling p-π conjugate system. This was performed to enable strong absorption of the R/tail-end band for the high probability of an n → π*/n → σ* electron transition for photoluminescence production. Subsequently, the Π₅⁶ structure was formed in a short-chain aliphatic molecule as a hydrolytic product of citric acid and urea, and computational methodology was employed to estimate the feasibility of the molecule photoluminescence. Finally, a quantum dot material was fabricated from the aliphatic molecule, the optical properties of the quantum dots were investigated, and the biocompatibility and bioimaging ability of quantum dots were assessed. This work presents not only a theoretical exploration but also practical application of a new strategy to obtain molecules, compounds, and materials with bioimaging.

Multishell Nanoparticles with "Linkage Mechanism" for Thermal Responsive Photodynamic and Gas Synergistic Therapy

The strategies of combining photodynamic therapy (PDT) with other therapeutics are considered to be the most suitable methods in improving the antitumor therapeutic efficiency. Herein, a "Linkage Mechanism" strategy based on thermal controllable multishell nanoparticles (CuS@SiO₂ -l-Arg (l-arginine)@PCM (phase-change material)-Ce6 (chiorin e6)) is proposed for combing PDT and NO-based gas therapy. Upon 1060 nm laser irradiation, the PCMs will melt under the photothermal effect induced by CuS and the loaded Ce6 and l-Arg can accurately release from the nanoparticles. Under further 660 nm laser irradiation, the released Ce6 will produce plenty of singlet oxygen (¹ O₂ ) for PDT, while the generated ¹ O₂ can oxidize l-Arg to release NO for the synergy of PDT and gas therapy. The "Linkage Mechanism" can achieve precise release of the payloads under the control of photothermal effect at tumor site, and the chain reaction of PDT and gas therapy overcomes the problem of premature release of gas during transportation. Benefiting from the guidance of fluorescence imaging and second near infrared photoacoustic imaging by Ce6 and CuS, both in vitro and in vivo experiments present effective antitumor efficiencies. The nanoparticles provide new ideas for controllable release of drugs and the synergistic effect of multiple treatments, possessing great application prospects.

Ferrite Nanoparticles-Based Reactive Oxygen Species-Mediated Cancer Therapy

Ferrite nanoparticles have been widely used in the biomedical field (such as magnetic targeting, magnetic resonance imaging, magnetic hyperthermia, etc.) due to their appealing magnetic properties. In tumor acidic microenvironment, ferrite nanoparticles show intrinsic peroxidase-like activities, which can catalyze the Fenton reaction of hydrogen peroxide (H₂O₂) to produce highly toxic hydroxyl free radicals (•OH), causing the death of tumor cell. Recent progresses in this field have shown that the enzymatic activity of ferrite can be improved via converting external field energy such as alternating magnetic field and near-infrared laser into nanoscale heat to produce more •OH, enhancing the killing effect on tumor cells. On the other hand, combined with other nanomaterials or drugs for cascade reactions, the production of reactive oxygen species (ROS) can also be increased to obtain more efficient cancer therapy. In this review, we will discuss the current status and progress of the application of ferrite nanoparticles in ROS-mediated cancer therapy and try to provide new ideas for this area.

Organic/inorganic nanohybrids rejuvenate photodynamic cancer therapy

The development of nanotechnology has changed the 100-year-old paradigm of photodynamic therapy (PDT), in which organic/inorganic hybrid nanomaterials have made great contributions. In this review, we first describe the mechanisms of PDT and discuss the limitations of conventional PDT. On this basis, we summarize recent progress in organic/inorganic nanohybrids-based photodynamic agents, highlighting how these nanohybrids can be programmed to overcome challenges in photodynamic cancer therapy.

Ligand-Targeted Delivery of Photosensitizers for Cancer Treatment

Photodynamic therapy (PDT) is a promising cancer treatment which involves a photosensitizer (PS), light at a specific wavelength for PS activation and oxygen, which combine to elicit cell death. While the illumination required to activate a PS imparts a certain amount of selectivity to PDT treatments, poor tumor accumulation and cell internalization are still inherent properties of most intravenously administered PSs. As a result, common consequences of PDT include skin photosensitivity. To overcome the mentioned issues, PSs may be tailored to specifically target overexpressed biomarkers of tumors. This active targeting can be achieved by direct conjugation of the PS to a ligand with enhanced affinity for a target overexpressed on cancer cells and/or other cells of the tumor microenvironment. Alternatively, PSs may be incorporated into ligand-targeted nanocarriers, which may also encompass multi-functionalities, including diagnosis and therapy. In this review, we highlight the major advances in active targeting of PSs, either by means of ligand-derived bioconjugates or by exploiting ligand-targeting nanocarriers.

Tailored core‒shell dual metal-organic frameworks as a versatile nanomotor for effective synergistic antitumor therapy

Malignant tumor has become an urgent threat to global public healthcare. Because of the heterogeneity of tumor, single therapy presents great limitations while synergistic therapy is arousing much attention, which shows desperate need of intelligent carrier for co-delivery. A core‒shell dual metal–organic frameworks (MOFs) system was delicately designed in this study, which not only possessed the unique properties of both materials, but also provided two individual specific functional zones for co-drug delivery. Photosensitizer indocyanine green (ICG) and chemotherapeutic agent doxorubicin (DOX) were stepwisely encapsulated into the nanopores of MIL-88 core and ZIF-8 shell to construct a synergistic photothermal/photodynamic/chemotherapy nanoplatform. Except for efficient drug delivery, the MIL-88 could be functioned as a nanomotor to convert the excessive hydrogen peroxide at tumor microenvironment into adequate oxygen for photodynamic therapy. The DOX release from MIL-88-ICG@ZIF-8-DOX nanoparticles was triggered at tumor acidic microenvironment and further accelerated by near-infrared (NIR) light irradiation. The in vivo antitumor study showed superior synergistic antitumor effect by concentrating the nanoparticles into dissolving microneedles as compared to intravenous and intratumoral injection of nanoparticles, with a significantly higher inhibition rate. It is anticipated that the multi-model synergistic system based on dual-MOFs was promising for further biomedical application.

Image-guided tumor surgery: The emerging role of nanotechnology

Surgical resection is a mainstay treatment for solid tumors. Yet, methods to distinguish malignant from healthy tissue are primarily limited to tactile and visual cues as well as the surgeon's experience. As a result, there is a possibility that a positive surgical margin (PSM) or the presence of residual tumor left behind after resection may occur. It is well-documented that PSMs can negatively impact treatment outcomes and survival, as well as pose an economic burden. Therefore, surgical tumor imaging techniques have emerged as a promising method to decrease PSM rates. Nanoparticles (NPs) have unique characteristics to serve as optical contrast agents during image-guided surgery (IGS). Recently, there has been tremendous growth in the volume and types of NPs used for IGS, including clinical trials. Herein, we describe the most recent contributions of nanotechnology for surgical tumor identification. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery Diagnostic Tools > in vivo Nanodiagnostics and Imaging.

Enhanced type I photoreaction of indocyanine green via electrostatic-force-driven aggregation

Owing to the strong NIR absorbance, indocyanine green (ICG) has attracted new attention in emerging photo-theranostics. However, ICG has a very low ROS production efficiency and mainly works through the type II photoreaction via its monomer. The aggregation tendency of ICG in aqueous milieus further worsens the scenario. Herein, ICG aggregates show an enhanced type I photoreaction pathway and have much better photooxidizing capability than its monomer, which improves the performance of ICG in the photodynamic inactivation of bacteria. This finding provides a feasible way to tackle the contradiction of ROS generation and ICG aggregation. Finally, the photodynamic effect of ICG aggregates was combined with the photothermal effect of gold nanorods to achieve an effective treatment of bacterial infection.

Highly Efficient 2D NIR-II Photothermal Agent with Fenton Catalytic Activity for Cancer Synergistic Photothermal-Chemodynamic Therapy

Photothermal therapy (PTT) has emerged as a promising cancer therapeutic modality with high therapeutic specificity, however, its therapeutic effectiveness is limited by available high-efficiency photothermal agents (PTAs), especially in the second near-infrared (NIR-II) biowindow. Here, based on facile liquid-exfoliated FePS3 nanosheets, a highly efficient NIR-II PTA with its photothermal conversion efficiency of up to 43.3% is demonstrated, which is among the highest reported levels in typical PTAs. More importantly, such Fe-based 2D nanosheets also show superior Fenton catalytic activity facilitated by their ultrahigh specific surface area, simultaneously enabling cancer chemodynamic therapy (CDT). Impressively, the efficiency of CDT could be further remarkably enhanced by its photothermal effect, leading to cancer synergistic PTT/CDT. Both in vitro and in vivo studies reveal a highly efficient tumor ablation under NIR-II light irradiation. This work provides a paradigm for cancer CDT and PTT in the NIR-II biowindow via a single 2D nanoplatform with desired therapeutic effect. Furthermore, with additional possibilities for magnetic resonance imaging, photoacoustic tomography, as well as drug loading, this Fe-based 2D material could potentially serve as a 2D "all-in-one" theranostic nanoplatform.

Manganese-Based Nanoplatform As Metal Ion-Enhanced ROS Generator for Combined Chemodynamic/Photodynamic Therapy

Reactive oxygen species (ROS) with strong oxidizing and high activity have been regarded as an effective "weapon" for antitumor therapy, since it can induce organelle injury, oxidative damage, and cell death. Herein, hollow structured manganese carbonate (MnCO₃) nanocubes are fabricated and loaded with photosensitizer (chlorin e6, Ce6), obtaining a responsive nanoplatform H-MnCO₃/Ce6-PEG (HMCP NCs). Two different approaches to upregulate intracellular ROS level were realized by HMCP NCs. On one hand, with irradiation of external laser, Ce6 could generate singlet oxygen (¹O₂) through a multistep photochemical process applied in photodynamic therapy (PDT). On the other hand, MnCO₃ could be specifically degraded into Mn²⁺ in an acidic tumor microenvironment (TME), triggering Mn²⁺-activated Fenton-like reaction to convert endogenous H₂O₂ into hydroxyl radical (•OH). In vitro combined chemodynamic therapy (CDT) and PDT showed that the metal ion-enhanced ROS production could break the intracellular redox equilibrium, thus leading to cell death. In vivo combined CDT/PDT with HMCP NCs exhibited remarkably enhanced therapeutic efficacy in inhibiting tumor growth, without resulting in noticeable damage to normal tissues. This work presents a unique type of manganese-based nanoplatform for efficiently generating ROS in solid tumors, favorable for ROS-involved therapeutic strategies.