Tumor acidity-activatable photothermal/Fenton nanoagent for synergistic therapy

The Rational Engineered Bacteria Based Biohybrid Living System for Tumor Therapy

Living therapy based on bacterial cells has gained increasing attention for their applications in tumor treatments. Bacterial cells can naturally target to tumor sites and active the innate immunological responses. The intrinsic advantages of bacteria attribute to the development of biohybrid living carriers for targeting delivery toward hypoxic environments. The rationally engineered bacterial cells integrate various functions to enhance the tumor therapy and reduce toxic side effects. In this review, the antitumor effects of bacteria and their application are discussed as living therapeutic agents across multiple antitumor platforms. The various kinds of bacteria used for cancer therapy are first introduced and demonstrated the mechanism of antitumor effects as well as the immunological effects. Additionally, this study focused on the genetically modified bacteria for the production of antitumor agents as living delivery system to treat cancer. The combination of living bacterial cells with functional nanomaterials is then discussed in the cancer treatments. In brief, the rational design of living therapy based on bacterial cells highlighted a rapid development in tumor therapy and pointed out the potentials in clinical applications.

Hetastarch-stabilized polypyrrole with hyperthermia-enhanced release and catalytic activity for synergistic antitumor therapy

Fenton catalytic medicine that catalyzes the production of ·OH without external energy input or oxygen as a substrate has reshaped the landscape of conventional cancer therapy in recent decades, yet potential biosafety concerns caused by non-safety-approved components restrict their clinical translation from the bench to the bedside. Herein, to overcome this dilemma, we elaborately utilizate safety-approved hetastarch, which has been extensively employed in the clinic as a plasma substitute, as a stabilizer participating in the copper chloride-initiated polymerization of pyrrole monomer before loading it with DOX. The constructed DOX-loaded hetastarch-doped Cu-based polypyrrole (HES@CuP-D) catalyzes the excess H2O2 in tumor cells to ·OH through a Cu+-mediated Fenton-like reaction, which not only causes oxidative damage to tumor cells but also leads to the structural collapse and DOX release. Additionally, HES@CuP-D together with laser irradiation reinforces tumor killing efficiency by hyperthermia-enhanced catalytic activity and -accelerated drug release. As a result, the developed HES@CuP-D provides a promising strategy for Fenton catalytic therapy with negligible toxicity to the body.

Nanoscale Two-Dimensional FeII- and CoII-Based Metal-Organic Frameworks of Porphyrin Ligand for the Photodynamic Therapy of Breast Cancer

The delivery of biocompatible reagents into cancer cells can elicit an anticancer effect by taking advantage of the unique characteristics of the tumor microenvironment (TME). In this work, we report that nanoscale two-dimensional FeII- and CoII-based metal-organic frameworks (NMOFs) of porphyrin ligand meso-tetrakis (6-(hydroxymethyl) pyridin-3-yl) porphyrin (THPP) can catalyze the generation of hydroxyl radicals (•OH) and O2 in the presence of H2O2 that is overexpressed in the TME. Photodynamic therapy consumes the generated O2 to produce a singlet oxygen (1O2). Both •OH and 1O2 are reactive oxygen species (ROS) that inhibit cancer cell proliferation. The FeII- and CoII-based NMOFs were non-toxic in the dark but cytotoxic when irradiated with 660 nm light. This preliminary work points to the potential of porphyrin-based ligands of transition metals as anticancer drugs by synergizing different therapeutic modalities.

Multifunctional nanoparticle for cancer therapy

Cancer is a complex disease associated with a combination of abnormal physiological process and exhibiting dysfunctions in multiple systems. To provide effective treatment and diagnosis for cancer, current treatment strategies simultaneously focus on various tumor targets. Based on the rapid development of nanotechnology, nanocarriers have been shown to exhibit excellent potential for cancer therapy. Compared with nanoparticles with single functions, multifunctional nanoparticles are believed to be more aggressive and potent in the context of tumor targeting. However, the development of multifunctional nanoparticles is not simply an upgraded version of the original function, but involves a sophisticated system with a proper backbone, optimized modification sites, simple preparation method, and efficient function integration. Despite this, many well-designed multifunctional nanoparticles with promising therapeutic potential have emerged recently. Here, to give a detailed understanding and analyzation of the currently developed multifunctional nanoparticles, their platform structures with organic or inorganic backbones were systemically generalized. We emphasized on the functionalization and modification strategies, which provide additional functions to the nanoparticle. We also discussed the application combination strategies that were involved in the development of nanoformulations with functional crosstalk. This review thus provides an overview of the construction strategies and application advances of multifunctional nanoparticles.

A new chitosan-based thermosensitive nanoplatform for combined photothermal and chemotherapy

Targeting the delivery of anti-cancer drugs to a tumor site is essential for effective treatment and to ensure minimal damage to healthy cells and tissues. In this work, a chitosan-based nanoplatform was constructed for combined photothermal therapy and chemotherapy of breast cancer. The pH-sensitive and biocompatible biopolymer chitosan (CS) was grafted with N-vinylcaprolactam (NVCL) and modified with biotin (Bio), imparting it with temperature sensitive property and also the ability for active targeting. The polymer self-assembled to give nanoparticles (NPs) loaded with indocyanine green (ICG) and doxorubicin (DOX). When the NPs are exposed to near-infrared (NIR) laser irradiation, ICG converts the light to heat, inducing a significant phase transition in the NPs and facilitating the release of the drug cargo. In addition, the solubility of chitosan is increased in the slightly acidic microenvironment of the tumor site, which also promotes drug release. A detailed analysis of the NPs both in vitro and in vivo showed that the carrier system is biocompatible, while the drug-loaded NPs are selectively taken up by cancer cells. Particularly when augmented with NIR irradiation, this leads to potent cell death in vitro and also in an in vivo murine xenograft model of breast cancer.

Synergistic chemotherapy and phototherapy based on red blood cell biomimetic nanomaterials

Novel drug delivery systems (DDSs) have become the mainstay of research in targeted cancer therapy. By combining different therapeutic strategies, potential DDSs and synergistic treatment approaches are needed to effectively deal with evolving drug resistance and the adverse effects of cancer. Nowadays, developing and optimizing human cell-based DDSs has become a new research strategy. Among them, red blood cells can be used as DDSs as they significantly enhance the pharmacokinetics of the transported drug cargo. Phototherapy, as a novel adjuvant in cancer treatment, can be divided into photodynamic therapy and photothermal therapy. Phototherapy using erythropoietic nanocarriers to mimic the unique properties of erythrocytes and overcome the limitations of existing DDSs shows excellent prospects in clinical settings. This review provides an overview of the development of photosensitizers and research on bio-nano-delivery systems based on erythrocytes and erythrocyte membranes that are used in achieving synergistic outcomes during phototherapy/chemotherapy.

Multifunctional nanotheranostics for near infrared optical imaging-guided treatment of brain tumors

Malignant brain tumors, a heterogeneous group of primary and metastatic neoplasms in the central nervous system (CNS), are notorious for their highly invasive and devastating characteristics, dismal prognosis and low survival rate. Recently, near-infrared (NIR) optical imaging modalities including fluorescence imaging (FLI) and photoacoustic imaging (PAI) have displayed bright prospect in innovation of brain tumor diagnoses, due to their merits, like noninvasiveness, high spatiotemporal resolution, good sensitivity and large penetration depth. Importantly, these imaging techniques have been widely used to vividly guide diverse brain tumor therapies in a real-time manner with high accuracy and efficiency. Herein, we provide a systematic summary of the state-of-the-art NIR contrast agents (CAs) for brain tumors single-modal imaging (e.g., FLI and PAI), dual-modal imaging (e.g., FLI/PAI, FLI/magnetic resonance imaging (MRI) and PAI/MRI) and triple-modal imaging (e.g., MRI/FLI/PAI and MRI/PAI/computed tomography (CT) imaging). In addition, we update the most recent progress on the NIR optical imaging-guided therapies, like single-modal (e.g., photothermal therapy (PTT), chemotherapy, surgery, photodynamic therapy (PDT), gene therapy and gas therapy), dual-modal (e.g., PTT/chemotherapy, PTT/surgery, PTT/PDT, PDT/chemotherapy, PTT/chemodynamic therapy (CDT) and PTT/gene therapy) and triple-modal (e.g., PTT/PDT/chemotherapy, PTT/PDT/surgery, PTT/PDT/gene therapy and PTT/gene/chemotherapy). Finally, we discuss the opportunities and challenges of the CAs and nanotheranostics for future clinic translation.

Iron-Based Hollow Nanoplatforms for Cancer Imaging and Theranostics

Over the past decade, iron (Fe)-based hollow nanoplatforms (Fe-HNPs) have attracted increasing attention for cancer theranostics, due to their high safety and superior diagnostic/therapeutic features. Specifically, Fe-involved components can serve as magnetic resonance imaging (MRI) contrast agents (CAs) and Fenton-like/photothermal/magnetic hyperthermia (MTH) therapy agents, while the cavities are able to load various small molecules (e.g., fluorescent dyes, chemotherapeutic drugs, photosensitizers, etc.) to allow multifunctional all-in-one theranostics. In this review, the recent advances of Fe-HNPs for cancer imaging and treatment are summarized. Firstly, the use of Fe-HNPs in single T1-weighted MRI and T2-weighted MRI, T1-/T2-weighted dual-modal MRI as well as other dual-modal imaging modalities are presented. Secondly, diverse Fe-HNPs, including hollow iron oxide (IO) nanoparticles (NPs), hollow matrix-supported IO NPs, hollow Fe-complex NPs and hollow Prussian blue (PB) NPs are described for MRI-guided therapies. Lastly, the potential clinical obstacles and implications for future research of these hollow Fe-based nanotheranostics are discussed.

Mitochondria-targeting Polydopamine-coated Nanodrugs for Effective Photothermal- and Chemo- Synergistic therapies Against Lung Cancer

Targeting mitochondria via nano platform emerged as an attractive anti-tumor pathway due to the central regulation role in cellar apoptosis and drug resistance. Here, a mitochondria-targeting nanoparticle (TOS-PDA-PEG-TPP) was designed to precisely deliver polydopamine (PDA) as the photothermal agent and alpha-tocopherol succinate (α-TOS) as the chemotherapeutic drug to the mitochondria of the tumor cells, which inhibits the tumor growth through chemo- and photothermal- synergistic therapies. TOS-PDA-PEG-TPP was constructed by coating PDA on the surface of TOS NPs self-assembled by α-TOS, followed by grafting PEG and triphenylphosphonium (TPP) on their surface to prolong the blood circulation time and target delivery of TOS and PDA to the mitochondria of tumor cells. In vitro studies showed that TOS-PDA-PEG-TPP could be efficiently internalized by tumor cells and accumulated at mitochondria, resulting in cellular apoptosis and synergistic inhibition of tumor cell proliferation. In vivo studies demonstrated that TOS-PDA-PEG-TPP could be efficiently localized at tumor sites and significantly restrain the tumor growth under NIR irradiation without apparent toxicity or deleterious effects. Conclusively, the combination strategy adopted for functional nanodrugs construction aimed at target-delivering therapeutic agents with different action mechanisms to the same intracellular organelles can be extended to other nanodrugs-dependent therapeutic systems.

Manganese-based hollow nanoplatforms for MR imaging-guided cancer therapies

Theranostic nanoplatforms integrating diagnostic and therapeutic functions have received considerable attention in the past decade. Among them, hollow manganese (Mn)-based nanoplatforms are superior since they combine the advantages of hollow structures and the intrinsic theranostic features of Mn2+. Specifically, the hollow cavity can encapsulate a variety of small-molecule drugs, such as chemotherapeutic agents, photosensitizers and photothermal agents, for chemotherapy, photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. After degradation in the tumor microenvironment (TME), the released Mn2+ is able to act simultaneously as a magnetic resonance (MR) imaging contrast agent (CA) and as a Fenton-like agent for chemodynamic therapy (CDT). More importantly, synergistic treatment outcomes can be realized by reasonable and optimized design of the hollow nanosystems. This review summarizes various Mn-based hollow nanoplatforms, including hollow MnxOy, hollow matrix-supported MnxOy, hollow Mn-doped nanoparticles, hollow Mn complex-based nanoparticles, hollow Mn-cobalt (Co)-based nanoparticles, and hollow Mn-iron (Fe)-based nanoparticles, for MR imaging-guided cancer therapies. Finally, we discuss the potential obstacles and perspectives of these hollow Mn-based nanotheranostics for translational applications. Mn-based hollow nanoplatforms such as hollow MnxOy nanoparticles, hollow matrix-supported MnxOy nanoparticles, Mn-doped hollow nanoparticles, Mn complex-based hollow nanoparticles, hollow Mn-Co-based nanoparticles and hollow Mn-Fe-based nanoparticles show great promise in cancer theranostics.

Recent Advances in Single Fe-Based Nanoagents for Photothermal-Chemodynamic Cancer Therapy

Monomodal cancer therapies are often unsatisfactory, leading to suboptimal treatment effects that result in either an inability to stop growth and metastasis or prevent relapse. Thus, synergistic strategies that combine different therapeutic modalities to improve performance have become the new research trend. In this regard, the integration of photothermal therapy (PTT) with chemodynamic therapy (CDT), especially PTT/CDT in the second near-infrared (NIR-II) biowindow, has been demonstrated to be a highly efficient and relatively safe concept. With the rapid development of nanotechnology, nanoparticles can be designed from specific elements, such as Fe, that are equipped with both PTT and CDT therapeutic functions. In this review, we provide an update on the recent advances in Fe-based nanoplatforms for combined PTT/CDT. The perspectives on further improvement of the curative efficiency are described, highlighting the important scientific obstacles that require resolution in order to reach greater heights of clinical success. We hope this review will inspire the interest of researchers in developing novel Fe-based nanomedicines for multifunctional theranostics.