A Fe2O3/CNx cascade nanoreactor with dual-enzyme-mimetic activities for cancer hypoxia relief to amplify chemo/photodynamic therapy

Reactive oxygen species (ROS)-mediated therapeutic strategies, including chemodynamic therapy (CDT), photodynamic therapy (PDT), and their combination, are effective for treating cancer. Developing a nanoreactor with combined functions of catalase (CAT) and peroxidase (POD) that can simultaneously convert excess H2O2 in tumors into O2 required for type II PDT and hydroxyl radicals (•OH) for CDT can help achieve combined therapy. Here, we reported on a safe Fe2O3/CNx nanoreactor with dual enzyme simulated activity, in which CNx sheet was the carrier and reducing agent to convert Fe2O3 to Fe2+. After modified by MgO2 and photosensitizer Ce6, MgO2-Fe2O3/CNx-Ce6 (MFCC) platform integrated multiple functions, including photosensitizer delivery, compensated H2O2 continuous supply, relieve of hypoxia, generation of •OH and consumption of GSH into a single formulation. Under 660 nm irradiation for 4 min, MFCC actives more ROS to conduct PDT/CDT, leading to the remarkable reduced survival rate of breast cancer cells to 14 %. Due to the enhanced permeability and retention (EPR) effect, MFCC can retain and accumulate at the tumor site of mice for a longer period that inhibit the expression of tumor angiogenic factors, suppress tumor neovascularization, and suppress the proliferation and growth of tumor cells.

NIR-II-Responsive CeO2-x@HA Nanotheranostics for Photoacoustic Imaging-Guided Sonodynamic-Enhanced Synergistic Phototherapy

The therapeutic effect of photothermal therapy (PTT) and photodynamic therapy (PDT) is severely limited because of the shallow tissue penetration depth of the first near-infrared (NIR-I) light. Multifunctional nanotheranostics irradiated by the second near-infrared (NIR-II) light have received wide interest with respect to deeper tissue penetration, and sonodynamic therapy (SDT) synergistic phototherapy can achieve the complete elimination of tumors. Herein, we successfully constructed a single NIR-II light-induced nanotheranostic using cerium oxide (CeO_2-x) with abundant oxygen vacancies for photoacoustic imaging-guided SDT-enhanced phototherapy for the first time. CeO_2-x with surface crystalline disorder showed extensive NIR-II region absorption and an outstanding photothermal conversion ability. In addition, the CeO_2-x layer with numerous oxygen defects can promote the separation of holes and electrons by ultrasound irradiation, which can remarkably enhance the efficacy of phototherapy to achieve high-efficiency tumor ablation. CeO_2-x was surface modified with hyaluronic acid (HA) to prepare CeO_2-x@HA to allow active tumor targeting efficiency. Both cell and animal experiments confirmed that all-in-one CeO_2-x@HA exhibited a high therapeutic efficacy of SDT-enhanced PDT/PTT under 1064 nm laser irradiation, which achieved complete tumor eradication without systemic toxicity. This study significantly broadened the application of NIR-II-responsive CeO_2-x for photoacoustic imaging-mediated SDT-enhanced phototherapy to the highly efficient and precise elimination of tumors.

Application of "smart" multifunctional nanoprobes in tumor diagnosis and treatment

Cancer is one of the major diseases that pose a threat to human health and life, especially because it is difficult to diagnose and cure, and recurs easily. In recent years, the development of nanotechnology has provided researchers with new tools for cancer treatment. In particular, nanoprobes that facilitate integrated diagnosis and treatment, high-resolution imaging, and accurate tumor targeting provide new avenues for the early detection and treatment of cancer. This review focuses on the preparations and applications of two kinds of "smart" multifunctional nanoprobes: "Off-On" nanoprobes and "Charge-Reversal" nanoprobes. This review also briefly discusses their mechanisms of action, as they could provide new ideas for the further development of this field.

Platinum prodrug nanoparticles inhibiting tumor recurrence and metastasis by concurrent chemoradiotherapy

Background

Although concurrent chemoradiotherapy (CRT), as one of the most effective antineoplastic therapies in clinic, can successfully inhibit the growth of tumor cells, a risk of developing secondary tumor is still an insurmountable barrier in clinical practice.

Results

Herein, a new platinum prodrug composed of tannic acid (TA) and Pt²⁺ (TA-Pt) complex film was synthesized on the surface of Fe₂O₃ nanoparticles (NPs) with excellent stability and biocompatibility for enhanced CRT. In this system, TA-Pt complex could respond to the tumor acidic microenvironment and damage the DNA of tumor cells. Moreover, the internal iron core not only improved the effect of subsequent radiotherapy (RT), but also disrupted the iron balance in cells, inducing intracellular ferroptosis and eliminating apoptosis-resistant cells. In vitro and vivo experimental results indicated that more than 90% of tumor cells were depleted and more than 75% of the cured tumor-bearing mice evinced no recurrence or metastasis.

Conclusions

This work offered a new idea for combining the effective chemotherapy, RT and ferroptosis therapy to enhance the curative effect of CRT and inhibit tumor recurrence and metastasis.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01322-y.

Precise Anti-Tumor Effect of a Metallopolysaccharide-Based Nanotheranostic: Turning Phototherapy into Programmed Chemotherapy

Phototheranostic, a regional-focused treatment, can endow cancer theranostic with low damage due to its spatial precision. However, precise elimination of residual cancer cells in laser-focused field and in non-laser-focused field...

Full-spectrum responsive WO3−x@HA nanotheranostics for NIR-II photoacoustic imaging-guided PTT/PDT/CDT synergistic therapy

A WO_3−x-based nanotheranostic has been successfully fabricated for photoacoustic imaging-guided synergistic tumor targeting therapy in the second near-infrared (NIR-II) biological window.

Recent Research on Methods to Improve Tumor Hypoxia Environment

Cancer is a major disease burden worldwide. In recent years, in addition to surgical resection, radiotherapy and chemotherapy are recognized as the most effective methods for treating solid tumors. These methods have been introduced to treat tumors of different origins and stages clinically. However, due to insufficient blood flow and oxygen (O2) supply in solid tumors, hypoxia is caused, leading to decreased sensitivity of tumor cells and poor therapeutic effects. In addition, hypoxia will also lead to resistance to most anticancer drugs, accelerate malignant progress, and increase metastasis. In solid tumors, adequate O2 supply and adequate delivery of anticancer drugs are essential to improve radiotherapy and chemotherapy sensitivity. In recent decades, the researches on relieving tumor hypoxia have attracted researchers' extensive attention and achieved good results. However, as far as we know, there is no detailed review of the researches on alleviating tumor hypoxia. Therefore, in this contribution, we hope to give an overview of the researches on methods to improve tumor hypoxia environment and summarize their effect and application in tumor therapy, to provide a methodological reference for the research and development of new antitumor agents.

Oxygen-producing catalase-based prodrug nanoparticles overcoming resistance in hypoxia-mediated chemo-photodynamic therapy

Extreme hypoxia inside solid tumors is the primary barrier against the advance of chemotherapy and photodynamic therapy (PDT). To address this problem, a hybrid nano-enzyme prodrug system was developed to alleviate hypoxia as well as simultaneously sensitize chemo-photodynamic therapy. Lactobionic acid (LA) and doxorubicin (DOX) precursor (cis-aconitic anhydride-linked doxorubicin, CAD) were pre-conjugated onto the side chain of catalase (CAT), then co-assembled with chlorin e6 (Ce6) to form LA-CAT-CAD@Ce6 nanoparticles (LCC@Ce6-NPs). LA as the active-targeting ligand increased cellular internalization, CAD as the pH-sensitive component triggered rapid drug release, Ce6 as the photosensitizer induced reactive oxygen species (ROS) generation, and CAT decomposed intracellular H₂O₂ to produce oxygen in situ. Oxygen production efficiently decreased the expression of hypoxia-inducible factor-1α (HIF-1α) and P-glycoprotein (P-gp), which enhanced chemotherapy efficiency. In addition, sufficient oxygen further amplified PDT-mediated cell-killing and apoptosis in hypoxic tumor. In vivo studies showed that combined chemo-photodynamic therapy by LCC@Ce6-NPs led to the most effective inhibition of tumor growth (TGI>90%), and even partially ablated tumor. Thus, this nano-enzyme prodrug platform can be a potentially effective treatment in clinical cancer therapy, and married to other therapeutic agents. STATEMENT OF SIGNIFICANCE: Hypoxia in solid tumors seriously impedes the efficacy of chemotherapy or photodynamic therapy. Herein, we designed hybrid nano-enzyme prodrug particles to improve hypoxia-mediated limitations on cancer therapy. Lactobionic acid (LA) as the hydrophilic outer layer of particles increased cellular uptake by receptor-mediated endocytosis, and cis-aconitic anhydride-linked doxorubicin (CAD) as the pH sensitive component inside particles efficiently triggered DOX and Ce6 release. More importantly, catalase (CAT) as the backbone of particles was capable of greatly relieving tumor hypoxia through catalyzing the decomposition of H2O2 in situ. Oxygen re-generation not only prevented hypoxia-mediated chemo-resistance, but also amplified PDT-induced ROS cell-killing ability. As a result, the multiple combination action of this nano-system could simultaneously sensitize chemo-photodynamic therapy, thus significantly enhancing tumor therapy.