Photothermal/photodynamic synergistic antibacterial study of MOF nanoplatform with SnFe2O4 as the core

Drug-resistant bacterial infections cause significant harm to public life, health, and property. Biofilm is characterized by overexpression of glutathione (GSH), hypoxia, and slight acidity, which is one of the main factors for the formation of bacterial resistance. Traditional antibiotic therapy gradually loses its efficacy against multi-drug-resistant (MDR) bacteria. Therefore, synergistic therapy, which regulates the biofilm microenvironment, is a promising strategy. A multifunctional nanoplatform, SnFe2O4-PBA/Ce6@ZIF-8 (SBC@ZIF-8), in which tin ferrite (SnFe2O4, denoted as SFO) as the core, loaded with 3-aminobenzeneboronic acid (PBA) and dihydroporphyrin e6 (Ce6), and finally coated with zeolite imidazole salt skeleton 8 (ZIF-8). The platform has a synergistic photothermal therapy (PTT)/photodynamic therapy (PDT) effect, which can effectively remove overexpressed GSH by glutathione peroxidase-like activity, reduce the antioxidant capacity of biofilm, and enhance PDT. The platform had excellent photothermal performance (photothermal conversion efficiency was 55.7 %) and photothermal stability. The inhibition rate of two MDR bacteria was more than 96 %, and the biofilm clearance rate was more than 90 % (150 μg/mL). In the animal model of MDR S. aureus infected wound, after 100 μL SBC@ZIF-8+NIR (150 μg/mL) treatment, the wound area of mice was reduced by 95 % and nearly healed. The serum biochemical indexes and H&E staining results were within the normal range, indicating that the platform could promote wound healing and had good biosafety. In this study, we designed and synthesized multifunctional nanoplatforms with good anti-drug-resistant bacteria effect and elucidated the molecular mechanism of its anti-drug-resistant bacteria. It lays a foundation for clinical application in treating wound infection and promoting wound healing.

Folate-modified liposomes mediate the co-delivery of cisplatin with miR-219a-5p for the targeted treatment of cisplatin-resistant lung cancer

Cisplatin (DDP) resistance, often leading to first-line chemotherapy failure in non-small cell lung cancer (NSCLC), poses a significant challenge. MiR-219a-5p has been reported to enhance the sensitivity of human NSCLC to DDP. However, free miR-219a-5p is prone to degradation by nucleases in the bloodstream, rendering it unstable. In light of this, our study developed an efficient nanodrug delivery system that achieved targeted delivery of DDP and miR-219a-5p by modifying liposomes with folate (FA). Based on the results of material characterization, we successfully constructed a well-dispersed and uniformly sized (approximately 135.8 nm) Lipo@DDP@miR-219a-5p@FA nanodrug. Agarose gel electrophoresis experiments demonstrated that Lipo@DDP@miR-219a-5p@FA exhibited good stability in serum, effectively protecting miR-219a-5p from degradation. Immunofluorescence and flow cytometry experiments revealed that, due to FA modification, Lipo@DDP@miR-219a-5p@FA could specifically bind to FA receptors on the surface of tumor cells (A549), thus enhancing drug internalization efficiency. Safety evaluations conducted in vitro demonstrated that Lipo@DDP@miR-219a-5p@FA exhibited no significant toxicity to non-cancer cells (BEAS-2B) and displayed excellent blood compatibility. Cellular functional experiments, apoptosis assays, and western blot demonstrated that Lipo@DDP@miR-219a-5p@FA effectively reversed DDP resistance in A549 cells, inhibited cell proliferation and migration, and further promoted apoptosis. In summary, the Lipo@DDP@miR-219a-5p@FA nanodrug, through specific targeting of cancer cells and reducing their resistance to DDP, significantly enhanced the anti-NSCLC effects of DDP in vitro, providing a promising therapeutic option for the clinical treatment of NSCLC.

GSH/pH dual responsive chitosan nanoparticles for reprogramming M2 macrophages and overcoming cancer chemoresistance

The combination of two or more drugs with different mechanisms of action is a promising strategy for circumventing multidrug resistance (MDR). However, the antitumor effect of nanosystems is usually limited due to the simultaneous release of different payloads at a single location rather than at their respective sites of action. Herein, we report a GSH and pH dual responsive nanoplatform encapsulated with doxorubicin (DOX) and resiquimod (R848) (GPNP) for combinatorial chemotherapy against cancer cells with drug resistance. GPNP possesses a core-shell structure wherein the polymer shell detaches in the acidic and sialic acid (SA)-rich environment. This leads to the release of R848 into the tumor microenvironment (TME), thereby reprogramming M2 macrophages into M1 macrophages and exposing the core CS(DOX)-PBA to kill MCF-7/ADR cells. Additionally, the nitric oxide (NO) generated by M1 macrophages can suppress the P-glycoprotein (P-gp) expression to reduce the efflux of chemotherapy drugs, thus playing a combined role in overcoming MDR. In vitro studies have demonstrated the effectiveness of GPNP in reprogramming M2 macrophages and inducing apoptosis in MCF-7/ADR cells, resulting in enhanced antitumor efficacy. This work proposed an effective combination strategy to combat chemoresistance, providing new insights into the development of innovative combinatorial therapies against MDR tumors.

The diverse effects of cisplatin on tumor microenvironment: Insights and challenges for the delivery of cisplatin by nanoparticles

Cisplatin is a well-known platinum-based chemotherapy medication that is widely utilized for some malignancies. Despite the direct cytotoxic consequences of cisplatin on tumor cells, studies in the recent decade have revealed that cisplatin can also affect different cells and their secretions in the tumor microenvironment (TME). Cisplatin has complex impacts on the TME, which may contribute to its anti-tumor activity or drug resistance mechanisms. These regulatory effects of cisplatin play a paramount function in tumor growth, invasion, and metastasis. This paper aims to review the diverse impacts of cisplatin and nanoparticles loaded with cisplatin on cancer cells and also non-cancerous cells in TME. The impacts of cisplatin on immune cells, tumor stroma, cancer cells, and also hypoxia will be discussed in the current review. Furthermore, we emphasize the challenges and prospects of using cisplatin in combination with other adjuvants and therapeutic modalities that target TME. We also discuss the potential synergistic effects of cisplatin with immune checkpoint inhibitors (ICIs) and other agents with anticancer potentials such as polyphenols and photosensitizers. Furthermore, the potential of nanoparticles for targeting TME and better delivery of cisplatin into tumors will be discussed.

Nanotechnology and curcumin: a novel and promising approach in digestive cancer therapy

This study reviews the application of nanotechnology and curcumin, a polyphenol extracted from turmeric, in treating digestive cancers, one of the most common types of malignancies worldwide. Despite curcumin's potential for inhibiting tumor growth, its clinical application is hindered by issues such as poor solubility and bioavailability. Nanomedicine, with its unique ability to enhance drug delivery and reduce toxicity, offers a solution to these limitations. The paper focuses on the development of nanoformulations of curcumin, such as nanoparticles and liposomes, that improve its bioavailability and efficacy in treating digestive cancers, including liver and colorectal cancers. The study serves as a valuable reference for future research and development in this promising therapeutic approach.

CaO2nanomedicines: a review of their emerging roles in cancer therapy

Metal peroxide-based nanomedicines have emerged as promising theranostic agents for cancer due to their multifunctional properties, including the generation of bioactive small molecules such as metal ions, H2O2, O2, and OH-. Among these metal peroxides, calcium peroxide (CaO2) nanomedicines have attracted significant attention due to their facile synthesis and good biocompatibility. CaO2nanoparticles have been explored for cancer treatment through three main mechanisms: (1) the release of O2, which helps alleviate tumor hypoxia and enhances oxygen-dependent therapies such as chemotherapy, photodynamic therapy, and immunotherapy; (2) the generation of H2O2, a precursor for ·OH generation, which enables cancer chemodynamic therapy; and (3) the release of Ca2+ions, which induce calcium overload and promote cell apoptosis (called ion-interference therapy). This review provides a comprehensive summary of recent examples of CaO2nanoparticle-based cancer therapeutic strategies, as well as discusses the challenges and future directions in the development of CaO2nanomedicines for cancer treatment.

A pH-responsive polymer-coated CaO2as oxygen-generating nanoparticlein situfor enhanced chemo-photodynamic synergistic therapy against tumors

Photodynamic therapy (PDT) has emerged as an efficient strategy for tumor treatment. However, Insufficient amounts of inherent hypoxia and intrinsic hydrogen peroxide (H2O2) in the tumor microenvironment severely constrained PDT, as oxygen is the critical substrate for photosensitivity reaction. Here, a pH-responsive H2O2and O2self-supplying hybrid nanoparticle was designed. Through, the calcium peroxide (CaO2) as carriers loading a chemotherapeutic drug a photosensitizer 5,10,15,20-tetrakis(4-aminophenyl) porphyrin (TAPP) and doxorubicin (DOX), was covered with polyacrylic acid (PAA) to build up a feature material DOX-TAPP-CaO2@OA@PAA (denoted as DTCOP) through the reverse microemulsion method. In the acidic tumor microenvironment conditions exposing the water-sensitive CaO2nanocore to generate hydrogen peroxide (H2O2) and O2, the self-supplied O2alleviates hypoxia to enhance the PDT, and releasing DOX and TAPP. Synthetic characterization shows that the succeeded synthesized Nanocarriers could effectively carry DOX and TAPP to the tumor site and release O2at the low pH of TME. And the experimental results demonstrated that this interpose exogenous oxygen strategy is efficient at inhibition of tumor growth bothin vitroandin vivo. The nanocomposite exhibits excellent biocompatibility and the ability to inhibit tumor growth and has significant potential for the treatment of hypoxic tumors.

Ginsenoside Rk1-Loaded Manganese-Doped Hollow Titania for Enhancing Tumor Sonodynamic Therapy via Upregulation of Intracellular Reactive Oxygen Species

Amplifying the intracellular reactive oxygen species (ROS) level remains an urgent challenge for efficient sonodynamic therapy (SDT) of tumors. Herein, by loading ginsenoside Rk1 with manganese-doped hollow titania (MHT), a Rk1@MHT sonosensitizer was conceived to strengthen the outcome of tumor SDT. The results verify that manganese-doping remarkably elevates the UV-visible absorption and decreases the bandgap energy of titania from 3.2 to 3.0 eV, which improves ROS production under ultrasonic irradiation. Immunofluorescence and Western blot analysis demonstrate that ginsenoside Rk1 can block the critical protein of the glutathione synthesis pathway, glutaminase, thus enhancing intracellular ROS by eliminating the endogenous glutathione-depleted pathway of ROS. Manganese-doping confers the nanoprobe T₁-weighted MRI function (r₂/r₁ = 1.41). Moreover, the in vivo tests confirm that Rk1@MHT-based SDT eradicates liver cancer in tumor-bearing mice via dual upregulation of intracellular ROS production. In summary, our study provides a new strategy for designing high-performance sonosensitizer to achieve noninvasive cancer treatment.

cRGD-targeted heparin nanoparticles for effective dual drug treatment of cisplatin-resistant ovarian cancer

Resistance to the chemotherapeutic agent cisplatin (DDP) is the primary reason for invalid chemotherapy of ovarian cancer. Given the complex mechanisms underlying chemo-resistance, the design of combination therapies based on blocking multiple mechanisms is a rationale to synergistically elevate therapeutic effect for effectively overcoming cancer chemo-resistance. Herein, we demonstrated a multifunctional nanoparticle (DDP-Ola@HR), which could simultaneously co-deliver DDP and Olaparib (Ola, DNA damage repair inhibitor) using targeted ligand cRGD peptide modified with heparin (HR) as nanocarrier, enabling the concurrent tackling of multiple resistance mechanisms to effectively inhibit the growth and metastasis of DDP-resistant ovarian cancer. In combination strategy, heparin could suppress the function of multidrug resistance-associated protein 2 (MRP2) and P-glycoprotein (P-gp) to promote the intracellular accumulation of DDP and Ola by specifically binding with heparanase (HPSE) to down-regulate PI3K/AKT/mTOR signaling pathway, and simultaneously served as a carrier combined with Ola to synergistically enhance the anti-proliferation ability of DDP for resistant ovarian cancer, thus achieving great therapeutic efficacy. Our DDP-Ola@HR could provide a simple and multifunctional combination strategy to trigger an anticipated cascading effect, thus effectively overcoming the chemo-resistance of ovarian cancer.

Ultrasound targeted microbubble destruction-triggered nitric oxide release via nanoscale ultrasound contrast agent for sensitizing chemoimmunotherapy

Immunotherapy had demonstrated inspiring effects in tumor treatment, but only a minority of people could benefit owing to the hypoxic and immune-suppressed tumor microenvironment (TME). Therefore, there was an urgent need for a strategy that could relieve hypoxia and increase infiltration of tumor lymphocytes simultaneously. In this study, a novel acidity-responsive nanoscale ultrasound contrast agent (L-Arg@PTX nanodroplets) was constructed to co-deliver paclitaxel (PTX) and L-arginine (L-Arg) using the homogenization/emulsification method. The L-Arg@PTX nanodroplets with uniform size of about 300 nm and high drug loading efficiency displayed good ultrasound diagnostic imaging capability, improved tumor aggregation and achieved ultrasound-triggered drug release, which could prevent the premature leakage of drugs and thus improve biosafety. More critically, L-Arg@PTX nanodroplets in combination with ultrasound targeted microbubble destruction (UTMD) could increase cellular reactive oxygen species (ROS), which exerted an oxidizing effect that converted L-Arg into nitric oxide (NO), thus alleviating hypoxia, sensitizing chemotherapy and increasing the CD8 + cytotoxic T lymphocytes (CTLs) infiltration. Combined with the chemotherapeutic drug PTX-induced immunogenic cell death (ICD), this promising strategy could enhance immunotherapy synergistically and realize powerful tumor treatment effect. Taken together, L-Arg@PTX nanodroplets was a very hopeful vehicle that integrated drug delivery, diagnostic imaging, and chemoimmunotherapy.

Ultrasound-Targeted Microbubble Disruption with Key Nanodroplets for Effective Ferroptosis in Triple-Negative Breast Cancer Using Animal Model

Introduction

Triple-negative breast cancer (TNBC) is known to be the most aggressive form of breast cancer. Due to its high recurrence and mortality rates, the treatment of TNBC is a significant challenge for the medical community. Besides, ferroptosis is an emerging regulatory cell death that may provide new insights into the treatment of TNBC. As a central inhibitor of the ferroptosis process, the selenoenzyme glutathione peroxidase 4 (GPX4) is its classical therapeutic target. However, inhibition of GPX4 expression is quite detrimental to normal tissues. Ultrasound contrast agents, as an emerging visualization precision treatment, may provide a solution to the existing problem.

Methods

In this study, nanodroplets (NDs) carrying simvastatin (SIM) were constructed using the homogeneous/emulsification method. Then, the characterization of SIM-NDs was systematically evaluated. Meanwhile, in this study, the ability of SIM-NDs combined with ultrasound-targeted microbubble disruption (UTMD) to initiate ferroptosis and its respective mechanisms of ferroptosis induction were verified. Finally, the antitumor activity of SIM-NDs was investigated in vitro and in vivo using MDA-MB-231 cells and TNBC animal models.

Results

SIM-NDs exhibited excellent pH- and ultrasound-responsive drug release and noticeable ultrasonographic imaging ability, also showing good biocompatibility and biosafety. UTMD could promote increased intracellular reactive oxygen species and consume intracellular glutathione. However, SIM-NDs were efficiently internalized into cells under ultrasound irradiation, followed by the rapid release of SIM, which inhibited intracellular mevalonate production, and synergistically downregulated GPX4 expression, thereby promoting ferroptosis. Moreover, this combined treatment demonstrated strong antitumor ability in vitro and in vivo.

Conclusion

The combination of UTMD and SIM-NDs presents a promising avenue for harnessing ferroptosis in the treatment of malignant tumors.

Targeting Tumor Microenvironment by Metal Peroxide Nanoparticles in Cancer Therapy

Solid tumors have a unique tumor microenvironment (TME), which includes hypoxia, low acidity, and high hydrogen peroxide and glutathione (GSH) levels, among others. These unique factors, which offer favourable microenvironments and nourishment for tumor development and spread, also serve as a gateway for specific and successful cancer therapies. A good example is metal peroxide structures which have been synthesized and utilized to enhance oxygen supply and they have shown great promise in the alleviation of hypoxia. In a hypoxic environment, certain oxygen-dependent treatments such as photodynamic therapy and radiotherapy fail to respond and therefore modulating the hypoxic tumor microenvironment has been found to enhance the antitumor impact of certain drugs. Under acidic environments, the hydrogen peroxide produced by the reaction of metal peroxides with water not only induces oxidative stress but also produces additional oxygen. This is achieved since hydrogen peroxide acts as a reactive substrate for molecules such as catalyse enzymes, alleviating tumor hypoxia observed in the tumor microenvironment. Metal ions released in the process can also offer distinct bioactivity in their own right. Metal peroxides used in anticancer therapy are a rapidly evolving field, and there is good evidence that they are a good option for regulating the tumor microenvironment in cancer therapy. In this regard, the synthesis and mechanisms behind the successful application of metal peroxides to specifically target the tumor microenvironment are highlighted in this review. Various characteristics of TME such as angiogenesis, inflammation, hypoxia, acidity levels, and metal ion homeostasis are addressed in this regard, together with certain forms of synergistic combination treatments.

Nanoscale CaO2 materials for synergistic transarterial chemoembolization in a VX2 orthotopic rabbit liver cancer model

Transcatheter arterial chemoembolization (TACE) is extensively used in the treatment of hepatocellular carcinoma (HCC), but its efficacy is usually limited to secondary tumor hypoxia and other progressive exacerbation of the abnormal tumor microenvironment (TME). Herein, we synthesized polyvinyl pyrrolidone (PVP)-coated CaO₂ nanoparticles (CaO₂ NPs) and applied them as a synergistic agent to improve the antitumor efficacy of TACE. After injection into the tumor, CaO₂ NPs reacted with water to generate abundant oxygen, hydroxyl ions (OH^-), and calcium ions (Ca²⁺), thereby relieving tumor hypoxia, neutralizing acid, and overloading Ca²⁺ to mediate antitumor effects. Moreover, the effect of chemotherapeutic drugs within the TACE was improved due to the modulated TME. CaO₂ NPs efficiently regulated the TME and improved the antitumor effect of doxorubicin under hypoxia conditions in vitro. Compared to other groups, the TACE+CaO₂ NPs group achieved the lowest tumor growth rate, highest tumor necrosis rate, lowest expression of histological markers associated with hypoxia and angiogenesis (HIF-α, VEGF, and CD31), and highest CD8⁺ T cell recruitment in vivo. Thus, these findings demonstrated that CaO₂ NPs provide synergy for TACE therapy in the VX2 orthotopic rabbit liver cancer model, suggesting that they have a potential broad clinical application. STATEMENT OF SIGNIFICANCE: The efficacy of transcatheter arterial chemoembolization (TACE) for treatment of hepatocellular carcinoma is usually limited to secondary tumor hypoxia and other progressive exacerbation of the abnormal tumor microenvironment (TME). To address this issue, we synthesized CaO₂ nanoparticles (CaO₂ NP_S) which would react with water to generate abundant oxygen, hydroxyl ions (OH^-), and calcium ions (Ca²⁺), thereby relieving tumor hypoxia, neutralizing the acidic TME, and inducing Ca²⁺ overloading. The efficacy of CaO₂ NPs in combination with TACE was investigated in an orthotopic rabbit liver cancer model, and the results showed the great synergetic antitumor effect of TACE and CaO₂ NPs.

Peroxide mediated oxygen delivery in cancer therapy

Hypoxia is a serious obstacle in cancer treatment. The aberrant vascular network as well as the abnormal extracellular matrix arrangement results in formation of a hypoxic regions in tumors which show high resistance to the curing. Hypoxia makes the cancer treatment challengeable via two mechanisms; first and foremost, hypoxia changes the cell metabolism and leads the cells towards an aggressive and metastatic phenotype and second, hypoxia decreases the efficiency of the various cancer treatment modalities. Most of the cancer treatment methods including chemotherapy, radiotherapy, photodynamic therapy, sonodynamic therapy and immunotherapy are negatively affected by the oxygen deprivation. Therefore, the regional oxygenation is requisite to alleviate the negative impacts of the hypoxia on tumor cells and tumor therapy modalities. A great deal of effort has been put forth to resolve the problem of hypoxia in tumors. Peroxides have gained tremendous attention as oxygen generating components in cancer therapy. The concurrent loading of the peroxides and cancer treatment components into a single delivery system can bring about a multipurpose delivery system and substantially encourage the success of the cancer amelioration. In this review, we have tried to after the description of a relation between hypoxia and cancer treatment modalities, discuss the role of peroxides in tumor hyperoxygenation and cancer therapy success. Thereafter, we have summarized a number of vehicles for the delivery of the peroxide alone or in combination with other therapeutic components for cancer treatment.

Noncovalent Dual-Locked Near-Infrared Fluorescent Probe for Precise Imaging of Tumor via Hypoxia/Glutathione Activation

Stimulus-responsive fluorescent probes have broad applications in the early detection and treatment of tumors and thus promote the personalized treatment of tumors and improve patient survival. Among the repertoires of probes, dual-locked near-infrared (NIR) fluorescent probes are of great significance due to their improved specificity and multiplex detection in tumor imaging but remain to be explored. In this work, a facile noncovalent strategy for constructing dual-locked probes was proposed. A glutathione (GSH)-activatable single-locked probe CySS (first lock) was preloaded into a hypoxia-responsive molecular container CF3C4A (second lock) through a host-guest interaction to form the dual-locked probe CF3C4A-CySS. Under physiological conditions, CF3C4A-CySS binds strongly to avoid undesired leakage in normal tissues. We have proven that CF3C4A-CySS can be activated and "turn on" its NIR fluorescent signal under the dual key stimulation of hypoxia and GSH in the tumor microenvironment, which enables precise tumor imaging with enhanced accuracy and specificity. Both in vitro and in vivo results indicated the superiority of CF3C4A-CySS in tumor imaging. This work not only provides an effective tool for tumor imaging but also proposes a promising strategy for dual-locked imaging agent construction.

Engineering nanomedicines to inhibit hypoxia-inducible Factor-1 for cancer therapy

Hypoxia-inducible factor-1 (HIF-1), an essential promoter of tumor progression, has attracted increasing attention as a therapeutic target. In addition to hypoxic cellular conditions, HIF-1 activation can be triggered by cancer treatment, which causes drug tolerance and therapeutic failure. To date, a series of effective strategies have been explored to suppress HIF-1 function, including silencing the HIF-1α gene, inhibiting HIF-1α protein translation, degrading HIF-1α protein, and inhibiting HIF-1 transcription. Furthermore, nanoparticle-based drug delivery systems have been widely developed to improve the stability and pharmacokinetics of HIF-1 inhibitors or achieve HIF-1-targeted combination therapies as a nanoplatform. In this review, we summarize the current literature on nanomedicines targeting HIF-1 to combat cancer and discuss their potential for future development.

A smart O2-generating nanocarrier optimizes drug transportation comprehensively for chemotherapy improving

Drug transportation is impeded by various barriers in the hypoxic solid tumor, resulting in compromised anticancer efficacy. Herein, a solid lipid monostearin (MS)-coated CaO₂/MnO₂ nanocarrier was designed to optimize doxorubicin (DOX) transportation comprehensively for chemotherapy enhancement. The MS shell of nanoparticles could be destroyed selectively by highly-expressed lipase within cancer cells, exposing water-sensitive cores to release DOX and produce O₂. After the cancer cell death, the core-exposed nanoparticles could be further liberated and continue to react with water in the tumor extracellular matrix (ECM) and thoroughly release O₂ and DOX, which exhibited cytotoxicity to neighboring cells. Small DOX molecules could readily diffuse through ECM, in which the collagen deposition was decreased by O₂-mediated hypoxia-inducible factor-1 inhibition, leading to synergistically improved drug penetration. Concurrently, DOX-efflux-associated P-glycoprotein was also inhibited by O₂, prolonging drug retention in cancer cells. Overall, the DOX transporting processes from nanoparticles to deep tumor cells including drug release, penetration, and retention were optimized comprehensively, which significantly boosted antitumor benefits.

Application of glutathione depletion in cancer therapy: Enhanced ROS-based therapy, ferroptosis, and chemotherapy

Glutathione (GSH) is an important member of cellular antioxidative system. In cancer cells, a high level of GSH is indispensable to scavenge excessive reactive oxygen species (ROS) and detoxify xenobiotics, which make it a potential target for cancer therapy. Plenty of studies have shown that loss of intracellular GSH makes cancer cells more susceptible to oxidative stress and chemotherapeutic agents. GSH depletion has been proved to improve the therapeutic efficacy of ROS-based therapy (photodynamic therapy, sonodynamic therapy, and chemodynamic therapy), ferroptosis, and chemotherapy. In this review, various strategies for GSH depletion used in cancer therapy are comprehensively summarized and discussed. First, the functions of GSH in cancer cells are analyzed to elucidate the necessity of GSH depletion in cancer therapy. Then, the synthesis and metabolism of GSH are briefly introduced to bring up some crucial targets for GSH modulation. Finally, different approaches to GSH depletion in the literature are classified and discussed in detail according to their mechanisms. Particularly, functional materials with GSH-consuming ability based on nanotechnology are elaborated due to their unique advantages and potentials. This review presents the ingenious application of GSH-depleting strategy in cancer therapy for improving the outcomes of various therapeutic regimens, which may provide useful guidance for designing intelligent drug delivery system.

Metal peroxides for cancer treatment

In recent years, metal peroxide (MO2) such as CaO2 has received more and more attention in cancer treatment. MO2 is readily decompose to release metal ions and hydrogen peroxide in the acidic tumor microenvironment (TME), resulting metal ions overloading, decreased acidity and elevated oxidative stress in TME. All of these changes making MO2 an excellent tumor therapeutic agent. Moreover, by combining MO2 with photosensitizers, enzymes or Fenton reagents, MO2 can assist and promote various tumor therapies such as photodynamic therapy and chemodynamic therapy. In this review, the synthesis and modification methods of MO2 are introduced, and the representative studies of MO2-based tumor monotherapy and combination therapy are discussed in detail. Finally, the current challenges and prospects of MO2 in the field of tumor therapy are emphasized to promote the development of MO2-based cancer treatment.

Nitric oxide-releasing micelles with intelligent targeting for enhanced anti-tumor effect of cisplatin in hypoxia

Background

Hypoxic tumor microenvironment (TME) promotes tumor metastasis and drug resistance, leading to low efficiency of cancer chemotherapy. The development of targeted agents or multi-target therapies regulating hypoxic microenvironment is an important approach to overcome drug resistance and metastasis.

Methods

In this study, chitosan oligosaccharide (COS)-coated and sialic acid (SA) receptor-targeted nano-micelles were prepared using film dispersion method to co-deliver cisplatin (CDDP) and nitric oxide (NO) (denoted as CTP/CDDP). In addition, we explored the mechanisms by which NO reversed CDDP resistance as well as enhanced anti-metastatic efficacy in hypoxic cancer cells.

Results

Because of the different affinities of COS and SA to phenylboronic acid (PBA) under different pH regimes, CTP/CDDP micelles with intelligent targeting property increased cellular uptake of CDDP and enhanced cytotoxicity to tumors, but reduced systemic toxicity to normal organs or tissues. In addition, CTP/CDDP showed stimulus-responsive release in TME. In terms of anti-tumor mechanism, CTP/CDDP reduced CDDP efflux and inhibited epithelial-mesenchymal transition (EMT) process of tumor by down-regulating hypoxia-inducible factor-1α (HIF-1α), glutathione (GSH), multidrug resistance-associated protein 2 (MRP2) and matrix metalloproteinase 9 (MMP9) expression, thus reversing drug resistance and metastasis of hypoxic tumor cells.

Conclusions

The designed micelles significantly enhanced anti-tumor effects both in vitro and in vivo. These results suggested that CTP/CDDP represented a promising strategy to treat resistance and metastatic tumors.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00989-z.

Nanocarriers Used in Drug Delivery to Enhance Immune System in Cancer Therapy

Cancer, a group of diseases responsible for the second largest cause of global death, is considered one of the main public health problems today. Despite the advances, there are still difficulties in the development of more efficient cancer therapies and fewer adverse effects for the patients. In this context, nanobiotechnology, a materials science on a nanometric scale specified for biology, has been developing and acquiring prominence for the synthesis of nanocarriers that provide a wide surface area in relation to volume, better drug delivery, and a maximization of therapeutic efficiency. Among these carriers, the ones that stand out are those focused on the activation of the immune system. The literature demonstrates the importance of this system for anticancer therapy, given that the best treatment for this disease also activates the immune system to recognize, track, and destroy all remaining tumor cells.

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.

Cyclic reactions-mediated self-supply of H2O2 and O2 for cooperative chemodynamic/starvation cancer therapy

Hydroxyl radical (·OH)-mediated chemodynamic therapy (CDT) and glucose oxidase (GOx)-based starvation therapy (ST) are two emerging antitumor strategies, limited by acid/H₂O₂ deficiency and tumor hypoxia, respectively. Herein, we developed a liposomal nanoplatform co-delivering Fe(OH)₃-doped CaO₂ nanocomposites and GOx molecules for synergistic CDT/ST with a complementary effect. Based on Fenton reactions initiated by iron ions, CaO₂-supplied H₂O₂ could not only generate ·OH for H₂O₂-sufficient CDT, but also produce O₂ to promote the catalytic efficiency of GOx under hypoxia. In return, the enhanced ST generated gluconic acid and H₂O₂, further amplifying CDT. Through in vitro and in vivo experiments, we demonstrated that such a mutually reinforced modality based on the cyclic Fenton/starvation reactions provided a novel and potent anticancer mechanism for the effective treatment of hypoxic cancers.

Methodology for characterization of platinum-based drug's targeted delivery nanosystems

Conventional anticancer therapies exploiting platinum-based drugs rely principally on the intravascular injection of the therapeutic agent. The anticancer drug is distributed throughout the body by the systemic blood circulation undergoing cellular uptake, rapid clearance and excretion. Consequently, only a small portion of the platinum-based drug reaches the tumor site, which is associated with severe side effects. For this reason, targeted delivery systems are of great need since they offer enhanced and selective delivery of a drug to cancerous cells making the therapy safe and more effective. Up to date, a variety of the Pt-based drug targeted delivery systems (Pt-based DTDSs) utilizing nanomaterials have been developed and tested using a range of analytical techniques that provided essential information on their synthesis, stability, biodistribution and cytotoxicity. Here we summarize those experimental techniques indicating their applicability at different stages of the research, as well as pointing out their strengths, advantages, drawbacks and limitations. Also, the existing strategies and approaches are critically reviewed with the objective to reveal and give rise to the development of the analytical methodology suitable for reliable Pt-based DTDSs characterization which would eventually result in novel therapies and better patients' outcomes.

CaO2/Fe3O4 nanocomposites for oxygen-independent generation of radicals and cancer therapy

The hypoxic tumor environment prevents the generation of reactive oxygen species (ROS), reducing the therapeutic efficiency. We construct oleylamine (OA) coated CaO₂/Fe₃O₄ nanocomposites to realize oxygen-independent generation of ROS and high efficient treatment of cancer. In the tumor site, CaO₂ reacts with water to generate H₂O₂, which can be catalized by Fe²⁺ that is produced by Fe₃O₄, to form highly toxic hydroxyl radicals (∙OH). To inhibit the premature reaction, CaO₂/Fe₃O₄ nanoparticles were coated with pH sensitive OA. The nanocomposites exhibited remarkable tumor growth inhibition ability and favorable biocompatibility, holding a great potential for hypoxic tumor therapy.

Tumor hypoxia: The major culprit behind cisplatin resistance in cancer patients

Cisplatin is the most commonly used first-line drug for cancer treatment. However, many patients develop resistance to cisplatin therapy which ultimately results in therapy failure and increased mortality. A growing body of evidence shows that the hypoxic microenvironment is the prime factor underlying tumor insensitivity to cisplatin treatment. Since tumors in the majority of cancer patients are under hypoxic stress (low oxygen supply), it becomes necessary to understand the pathobiology behind hypoxia-induced cisplatin resistance in cancer cells. Here, we discuss the molecular events that render hypoxic tumors insensitive to cisplatin therapy. Furthermore, various drugs and tumor oxygenation techniques have been developed to circumvent cisplatin resistance in hypoxic tumors. However, their pharmaceutical applications are limited due to failures in clinical investigations and a lack of preclinical studies in the hypoxic tumor microenvironment. This review addresses these challenges and provides new directions for the strategic deployment of cisplatin sensitizers in the hypoxic tumor microenvironment.

F127/Cisplatin Microemulsions: In Vitro, In Vivo and Computational Studies

The development of effective strategies for local administration of chemotherapeutic drugs, thus minimizing the adverse side effects to patients, is one of the key challenges in biomedicine and cancer research. This work reports the formulation and characterization of PluronicF127 microemulsions to enhance the bioavailability of Cisplatin (Cis). The size of Cis microemulsion was about 12.0 nm, as assessed by dynamic light scattering analysis. In vitro cytotoxic activity of free Cis and F127/Cis microemulsions were studied on malignant (C152 and MCF7) and normal (HUVEC) cells via tetrazolium (MTT) colorimetric assay. Cell morphology was also monitored. In vitro assessments revealed thatF127/Cis microemulsions induced cytotoxicity/morphological changes to a lesser extent than free Cis. Regarding in vivo experiments, F127/Cis microemulsions were injected intraperitoneally at 7 and 14 mg/kg doses into adult male Wistar rats to assess histologic and biochemical changes. In this case, the bulk Cis group caused severe histopathological changes and significant increases in serum liver enzymes and serum kidney function markers. The group treated with the 14 mg/kg dose of F127/Cis microemulsions also showed severe fatty changes and significant increases in serum liver enzymes, blood urea nitrogen, and creatinine levels. The group treated with the low dose of nano-Cis showed a significant increase in serum liver enzymes levels accompanied by mild fatty changes of the liver. Theoretical surveys were performed to get an understanding of the interplay between F127 and Cis. Results reveal that hydrogen bonding (HB) interactions with F127have an influence on the molecular properties of Cis and may playa role in the lower toxicity of F127/Cis in comparison to free Cis.

A solid lipid coated calcium peroxide nanocarrier enables combined cancer chemo/chemodynamic therapy with O2/H2O2 self-sufficiency

The unfavorable factors in tumor microenvironment such as hypoxia and limited H₂O₂ levels greatly impede the anticancer efficacy of chemotherapy and chemodynamic therapy (CDT). To address these issues and achieve O₂/H₂O₂-sufficient chemo/chemodynamic combination therapy, we synthesized a solid lipid monostearin coated calcium peroxide (CaO₂) nanocarrier for the co-delivery of a chemotherapeutic drug doxorubicin (DOX) and a biocompatible Fenton catalyst iron-oleate complex. Specifically, the solid lipid shells of nanoparticles could disintegrate in lipase-overexpressed cancer cells to release iron-oleate and expose CaO₂ cores. Afterwards, the uncovered CaO₂ responded to the acidic aqueous environment within cancer cells, leading to the release of DOX molecules and generation of H₂O₂. Based on Fenton reactions, Fe³⁺ liberated from iron-oleate reacted with H₂O₂ to produce O₂ for hypoxia-relieved chemotherapy, and Fe²⁺ for the catalytic generation of hydroxyl radical to initiate CDT. Both treatments synergistically contribute to the enhanced antitumor outcomes.

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.

The tumour microenvironment and metabolism in renal cell carcinoma targeted or immune therapy

Renal cell carcinoma (RCC) is one of the most common tumours of the urinary system, and is insidious and not susceptible to chemoradiotherapy. As the most common subtype of RCC (70-80% of cases), clear cell renal cell carcinoma (ccRCC) is characterized by the loss of von Hippel-Lindau and the accumulation of robust lipid and glycogen. For advanced RCC, molecular-targeted drugs, tyrosine kinase inhibitors (TKIs) and the immune checkpoint inhibitors (ICIs) have been increasingly recommended and investigated. Due to the existence of a highly dynamic, adaptive and heterogeneous tumour microenvironment (TME), and due to the glucose and lipid metabolism in RCC, this cancer may be accompanied by various types of resistance to TKIs and ICIs. With the increased production of lactate, nitric oxide, and other new by-products of metabolism, novel findings of the TME and key metabolic enzymes drived by HIF and other factors have been increasingly clarified in RCC carcinogenesis and therapy. However, there are few summaries of the TME and tumour metabolism for RCC progression and therapy. Here, we summarize and discuss the relationship of the important implicated characteristics of the TME as well as metabolic molecules and RCC carcinogenesis to provide prospects for future treatment strategies to overcome TME-related resistance in RCC.

Nano Encapsulated Curcumin: And Its Potential for Biomedical Applications

Curcumin, a yellow-colored polyphenol extracted from the rhizome of turmeric root, is commonly used as a spice and nutritional supplement. It exhibits many pharmacological activities such as anti-inflammatory, anti-bacterial, anti-cancer, anti-Alzheimer, and anti-fungal. However, the therapeutic application of curcumin is limited by its extremely low solubility in aqueous buffer, instability in body fluids, and rapid metabolism. Nano delivery system has shown excellent potential to improve the solubility, biocompatibility and therapeutic effect of curcumin. In this review, we focus on the recent development of nano encapsulated curcumin and its potential for biomedical applications.

One-pot synthesis of a microporous organosilica-coated cisplatin nanoplatform for HIF-1-targeted combination cancer therapy

Nanoparticle formulations have proven effective for cisplatin delivery. However, the development of a versatile nanoplatform for cisplatin-based combination cancer therapies still remains a great challenge.

Methods: In this study, we developed a one-pot synthesis method for a microporous organosilica shell-coated cisplatin nanoplatform using a reverse microemulsion method, and explored its application in co-delivering acriflavine (ACF) for inhibiting hypoxia-inducible factor-1 (HIF-1).

Results: The resulting nanoparticles were tunable, and they could be optimized to a monodisperse population of particles in the desired size range (40-50 nm). In addition, organic mPEG2000-silane and tetrasulfide bond-bridged organosilica were integrated into the surface and silica matrix of nanoparticles for prolonged blood circulation and tumor-selective glutathione-responsive degradation, respectively. After reaching the tumor sites, cisplatin induced cancer cell death and activated HIF-1 pathways, resulting in acquired drug resistance and tumor metastasis. To address this issue, ACF was co-loaded with cisplatin to prevent the formation of HIF-1α/β dimers and suppress HIF-1 function. Hence, the efficacy of cisplatin was improved, and cancer metastasis was inhibited.

Conclusion: Both in vitro and in vivo results suggested that this core-shell nanostructured cisplatin delivery system represented a highly efficacious and promising nanoplatform for the synergistic delivery of combination therapies involving cisplatin.

Chemoreactive Nanotherapeutics by Metal Peroxide Based Nanomedicine

The advances of nanobiotechnology and nanomedicine enable the triggering of in situ chemical reactions in disease microenvironment for achieving disease-specific nanotherapeutics with both intriguing therapeutic efficacy and mitigated side effects. Metal peroxide based nanoparticles, as one of the important but generally ignored categories of metal-involved nanosystems, can function as the solid precursors to produce oxygen (O2) and hydrogen peroxide (H2O2) through simple chemical reactions, both of which are the important chemical species for enhancing the therapeutic outcome of versatile modalities, accompanied with the unique bioactivity of metal ion based components. This progress report summarizes and discusses the most representative paradigms of metal peroxides in chemoreactive nanomedicine, including copper peroxide (CuO2), calcium peroxide (CaO2), magnesium peroxide (MgO2), zinc peroxide (ZnO2), barium peroxide (BaO2), and titanium peroxide (TiOx) nanosystems. Their reactions and corresponding products have been broadly explored in versatile disease treatments, including catalytic nanotherapeutics, photodynamic therapy, radiation therapy, antibacterial infection, tissue regeneration, and some synergistically therapeutic applications. This progress report particularly focuses on the underlying reaction mechanisms on enhancing the therapeutic efficacy of these modalities, accompanied with the discussion on their biological effects and biosafety. The existing gap between fundamental research and clinical translation of these metal peroxide based nanotherapeutic technologies is finally discussed in depth.

Nanoparticle facilitated delivery of peroxides for effective cancer treatments

Peroxide nanoparticles increase the intratumoral H₂O₂ concentration for the catalytic production of ˙OH and O₂, which further enhance O₂/ROS-dependent anticancer therapies.