Designing Mesoporous Prussian Blue@zinc Phosphate Nanoparticles with Hierarchical Pores for Varisized Guest Delivery and Photothermally-Augmented Chemo-Starvation Therapy

Background

With the rapid development of nanotechnology, constructing a multifunctional nanoplatform that can deliver various therapeutic agents in different departments and respond to endogenous/exogenous stimuli for multimodal synergistic cancer therapy remains a major challenge to address the inherent limitations of chemotherapy.

Methods

Herein, we synthesized hollow mesoporous Prussian Blue@zinc phosphate nanoparticles to load glucose oxidase (GOx) and DOX (designed as HMPB-GOx@ZnP-DOX NPs) in the non-identical pore structures of their HMPB core and ZnP shell, respectively, for photothermally augmented chemo-starvation therapy.

Results

The ZnP shell coated on the HMPB core, in addition to providing space to load DOX for chemotherapy, could also serve as a gatekeeper to protect GOx from premature leakage and inactivation before reaching the tumor site because of its degradation characteristics under mild acidic conditions. Moreover, the loaded GOx can initiate starvation therapy by catalyzing glucose oxidation while causing an upgradation of acidity and H2O2 levels, which can also be used as forceful endogenous stimuli to trigger smart delivery systems for therapeutic applications. The decrease in pH can improve the pH-sensitivity of drug release, and O2 can be supplied by decomposing H2O2 through the catalase-like activity of HMPBs, which is beneficial for relieving the adverse conditions of anti-tumor activity. In addition, the inner HMPB also acts as a photothermal agent for photothermal therapy and the generated hyperthermia upon laser irradiation can serve as an external stimulus to further promote drug release and enzymatic activities of GOx, thereby enabling a synergetic photothermally enhanced chemo-starvation therapy effect. Importantly, these results indicate that HMPB-GOx@ZnP-DOX NPs can effectively inhibit tumor growth by 80.31% and exhibit no obvious systemic toxicity in mice.

Conclusion

HMPB-GOx@ZnP-DOX NPs can be employed as potential theranostic agents that incorporate multiple therapeutic modes to efficiently inhibit tumors.

Recent advances in Prussian blue-based photothermal therapy in cancer treatment

Malignant tumours are a serious threat to human health. Traditional chemotherapy has achieved breakthrough improvements but also has significant detrimental effects, such as the development of drug resistance, immunosuppression, and even systemic toxicity. Photothermal therapy (PTT) is an emerging cancer therapy. Under light irradiation, the phototherapeutic agent converts optical energy into thermal energy and induces the hyperthermic death of target cells. To date, numerous photothermal agents have been developed. Prussian blue (PB) nanoparticles are among the most promising photothermal agents due to their excellent physicochemical properties, including photoacoustic and magnetic resonance imaging properties, photothermal conversion performance, and enzyme-like activity. By the construction of suitably designed PB-based nanotherapeutics, enhanced photothermal performance, targeting ability, multimodal therapy, and imaging-guided cancer therapy can be effectively and feasibly achieved. In this review, the recent advances in PB-based photothermal combinatorial therapy and imaging-guided cancer therapy are comprehensively summarized. Finally, the potential obstacles of future research and clinical translation are discussed.

Tailoring bismuth-based nanoparticles for enhanced radiosensitivity in cancer therapy

Achieving a complete response to cancer treatment is a severe challenge, and has puzzled humans for a long time. Fortunately, radiotherapy (RT) gives rise to a common clinical treatment method, during which the usage of radiosensitizers is essential. Among preclinical radiosensitizers, bismuth-based nanoparticles (Bi-based NPs) are widely explored in cancer diagnosis and treatment, because they share favourable properties, such as low toxicity, strong X-ray absorption and facile preparation. However, pure Bi alone cannot achieve both efficient and safe RT outcomes, mainly due to poor targeting of tumor sites, long retention-induced systemic toxicity and immune resistance. This work provides an overview of recent advances and developments in Bi-based NPs that are tailored to enhance radiosensitivity. For the fabrication process, surface modification of Bi-based NPs is essential to achieve tumor-targeted delivery and penetration. Moreover, the incorporation of other elements, such as Fe ions, can increase diagnostic accuracy with optimal theranostic efficacy. Meanwhile, the structure-activity relationship can also be manipulated to maximize the chemotherapeutic drug loading capability of Bi-based NPs, to enhance X-ray attenuation by means of a large surface area or to achieve safer metabolic routes with rapid clearance from the human body. In addition, Bi-based NPs exhibit synergistic antitumor potential when combined with diverse therapies, such as photothermal therapy (PTT) and high-intensity focused ultrasound (HIFU). To summarize, the latest research on Bi-based NPs as radiosensitizers is described in the review, including both their advantages and disadvantages for improving treatment, thus providing a useful guide for future clinical application.

A multifunctional nanoplatform for improving microwave hyperthermia by a combination therapy of vessel disruptive agent and immune modulator

Microwave (MW) hyperthermia is one of the safest and most efficient minimally invasive tumor treatment methods, it is restricted by the bottlenecks of the heat sink effect and ineffective immune activation. Herein, a multifunctional nano platform with the load of nano immune modulator bimetallic metal-organic framework (BM), tumor vessel destructive agent and prodrug for gas production is developed for improving MW hyperthermia. Specifically, the combretastatin A4 phosphate (CA4P) was a vessel destructive agent to reduce MW heat loss by destructing the tumor blood vessel. Moreover, the as designed BM can scavenge the endogenic reactive oxygen species, which is conducive to hydrogen sulfide gas (H₂S) that produced by bismuth sulfide (Bi₂S₃) to activate immune cells. Our in vivo experimental results demonstrate the destruction of tumor blood vessels coupled with the activated immune system results in the remarkable antitumor effect. This study provides an efficient strategy to improve MW hyperthermia by a combination of vasculature-targeting therapy with systemic immunity.

Multifunctional high-Z nanoradiosensitizers for multimodal synergistic cancer therapy

Radiotherapy (RT) is one of the most common and effective clinical therapies for malignant tumors. However, there are several limitations that undermine the clinical efficacy of cancer RT, including the low X-ray attenuation coefficient of organs, serious damage to normal tissues, and radioresistance in hypoxic tumors. With the rapid development of nanotechnology and nanomedicine, high-Z nanoradiosensitizers provide novel opportunities to overcome radioresistance and improve the efficacy of RT by deposition of radiation energy through photoelectric effects. To date, several types of nanoradiosensitizers have entered clinical trials. Nevertheless, the limitation of the single treatment mode and the unclear mechanism of nanoparticle radiosensitization have hindered the further development of nanoradiosensitizers. In this review, we systematically describe the interaction mechanisms between X-rays and nanomaterials and summarize recent advances in multifunctional high-Z nanomaterials for radiotherapeutic-based multimodal synergistic cancer therapy. Finally, the challenges and prospects are discussed to stimulate the development of nanomedicine-based cancer RT.

Autocatalytic oncotherapy nanosystem with glucose depletion for cascade amplification of hypoxia-activated chemotherapy and H2O2-dependent chemodynamic therapy

Hypoxia-activated prodrug is an appealing oncotherapy strategy, but limited by insufficient tumor hypoxia. Moreover, standalone prodrug fails to treat tumor satisfactorily due to tumor complexity. Herein, a nanosystem (TPZ@FeMSN-GOX) was...

An Injectable Hydrogel for Enhanced FeGA-Based Chemodynamic Therapy by Increasing Intracellular Acidity

Hydroxyl radical (•OH)-mediated chemodynamic therapy (CDT) is an emerging antitumor strategy, however, acid deficiency in the tumor microenvironment (TME) hampers its efficacy. In this study, a new injectable hydrogel was developed as an acid-enhanced CDT system (AES) for improving tumor therapy. The AES contains iron-gallic acid nanoparticles (FeGA) and α-cyano-4-hydroxycinnamic acid (α-CHCA). FeGA converts near-infrared laser into heat, which results in agarose degradation and consequent α-CHCA release. Then, as a monocarboxylic acid transporter inhibitor, α-CHCA can raise the acidity in TME, thus contributing to an increase in ·OH-production in FeGA-based CDT. This approach was found effective for killing tumor cells both in vitro and in vivo, demonstrating good therapeutic efficacy. In vivo investigations also revealed that AES had outstanding biocompatibility and stability. This is the first study to improve FeGA-based CDT by increasing intracellular acidity. The AES system developed here opens new opportunities for effective tumor treatment.

Engineering nanomedicine for glutathione depletion-augmented cancer therapy

Glutathione (GSH), the main redox buffer, has long been recognized as a pivotal modulator of tumor initiation, progression and metastasis. It is also implicated in the resistance of platinum-based chemotherapy and radiation therapy. Therefore, depleting intracellular GSH was considered a potent solution to combating cancer. However, reducing GSH within cancer cells alone always failed to yield desirable therapeutic effects. In this regard, the convergence of GSH-scavenging agents with therapeutic drugs has thus been pursued in clinical practice. Unfortunately, the therapeutic outcomes are still unsatisfactory due to untargeted drug delivery. Advanced nanomedicine of synergistic GSH depletion and cancer treatment has attracted tremendous interest because they promise to deliver superior therapeutic benefits while alleviating life-threatening side effects. In the past five years, the authors and others have demonstrated that numerous nanomedicines, by simultaneously delivering GSH-depleting agents and therapeutic components, boost not only traditional chemotherapy and radiotherapy but also multifarious emerging treatment modalities, including photodynamic therapy, sonodynamic therapy, chemodynamic therapy, ferroptosis, and immunotherapy, to name a few, and achieved decent treatment outcomes in a large number of rodent tumor models. In this review, we summarize the most recent progress in engineering nanomedicine for GSH depletion-enhanced cancer therapies. Biosynthesis of GSH and various types of GSH-consuming strategies will be briefly introduced. The challenges and perspectives of leveraging nanomedicine for GSH consumption-augmented cancer therapies will be discussed at the end.

Responsive Degradable Theranostic Agents Enable Controlled Selenium Delivery to Enhance Photothermal Radiotherapy and Reduce Side Effects

Radiotherapy (RT) is a popular clinical therapy method for extending cancer patient survival, but is hampered by severe side effects and the weak therapy effect. Herein, responsive degradable selenium (Se) theranostic agents (Se@SiO₂ @Bi nanocomposites (NCs)) are fabricated, which combine computed tomography (CT) imaging and simultaneously enhance the therapeutic effects of photothermal therapy (PTT) and RT, while reducing the side effects of radiation. The Se@SiO₂ @Bi theranostic agents can accumulate at the tumor site, and responsively decompose to releease Se, avoiding systemic toxicity by the element. Se enhances the effect of PTT/RT, simultaneously reducing the side effects of RT. The Se@SiO₂ @Bi NCs as CT agents also exhibit significantly enhanced contrast imaging performance due to the high atomic number of Bi. More importantly, the Se@SiO₂ @Bi NCs can be rapidly excreted without long-term toxicity, owing to responsive degradation into ultrasmall particles (<5 nm) at the tumor site. In vitro and in vivo results show that the Se@SiO₂ @Bi NCs can remarkably inhibit tumor cells, without causing appreciable toxicity during the treatment. This study opens a new perspective in rationally designing responsive degradable theranostic agents for future tumor therapy with enhanced therapeutic efficacy and lesser side effects.

Metal-ligand coordination nanomaterials for radiotherapy: emerging synergistic cancer therapy

Radiotherapy (RT) plays a central role in curing malignant tumors. However, the treatment outcome is often impeded by low radiation absorption coefficients and radiation resistance of tumors along with normal tissue radio-toxicity. With the development of nanotechnology, nanomaterials in combination with RT offer the possibility to improve the therapeutic efficacy yet reduce side-effects. Metal-ligand coordination nanomaterials, including nanoscale metal-organic frameworks (NMOFs) and nanoscale coordination polymers (NCPs), formed by coordination interactions between inorganic metal ions/clusters with organic bridging ligands, have shown great potential in the field of radiation oncology in recent years in view of their unique advantages including the porous structure, high surface area, periodic frameworks, and diverse selections of both metal ions/clusters and organic ligands. In this review, we summarize the recent advances in NMOF/NCP-mediated synergistic RT in combination with hypoxia relief, chemotherapy, photodynamic therapy, photothermal therapy, chemodynamic therapy or immunotherapy, which emerged in the last 3 years, and describe cooperative enhancement interactions among these synergistic combinations. Moreover, the potential challenges and future prospects of this rapidly growing direction were also addressed.

Designing heterostructured core@satellite Prussian Blue Analogue@Au–Ag nanoparticles: Effect on the magnetic properties and catalytic activity

Prussian Blue Analogue@Au–Ag nanoparticles: Effect on the magnetic properties and catalytic activity.

Finely tuned Prussian blue-based nanoparticles and their application in disease treatment

The Prussian blue (PB) based nanostructure is a mixed-valence coordination network with excellent biosafety, remarkable photothermal effect and multiple enzyme-mimicking behaviours. Compared with other nanomaterials, PB-based nanoparticles (NPs) exhibit several unparalleled advantages in biomedical applications. This review begins with the chemical composition and physicochemical properties of PB-based NPs. The tuning strategies of PB-based NPs and their biomedical properties are systemically demonstrated. Afterwards, the biomedical applications of PB-based NPs are comprehensively recounted, mainly focusing on treatment of tumors, bacterial infection and inflammatory diseases. Finally, the challenges and future prospects of PB-based NPs and their application in disease treatment are discussed.