Copper and Copper Complexes in Tumor Therapy

Copper (Cu), a crucial trace element in physiological processes, has garnered significant interest for its involvement in cancer progression and potential therapeutic applications. The regulation of cellular copper levels is essential for maintaining copper homeostasis, as imbalances can lead to toxicity and cell death. The development of drugs that target copper homeostasis has emerged as a promising strategy for anticancer treatment, with a particular focus on copper chelators, copper ionophores, and novel copper complexes. Recent research has also investigated the potential of copper complexes in cancer therapy.

Cancer Radiosensitization Nanoagent to Activate cGAS-STING Pathway for Molecular Imaging Guided Synergistic Radio/Chemo/Immunotherapy

Immunotherapy has emerged as an innovative strategy with the potential to improve outcomes in cancer patients. Recent evidence indicates that radiation-induced DNA damage can activate the cyclic-GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway to enhance the antitumor immune response. Even so, only a small fraction of patients currently benefits from radioimmunotherapy due to the radioresistance and the inadequate activation of the cGAS-STING pathway. Herein, this work integrates hafnium oxide (HfO2) nanoparticles (radiosensitizer) and 7-Ethyl-10-hydroxycamptothecin (SN38, chemotherapy drug, STING agonist) into a polydopamine (PDA)-coated core-shell nanoplatform (HfO2@PDA/Fe/SN38) to achieve synergistic chemoradiotherapy and immunotherapy. The co-delivery of HfO2/SN38 greatly enhances radiotherapy efficacy by effectively activating the cGAS-STING pathway, which then triggers dendritic cells maturation and CD8+ T cells recruitment. Consequently, the growth of both primary and abscopal tumors in tumor-bearing mice is efficiently inhibited. Moreover, the HfO2@PDA/Fe/SN38 complexes exhibit favorable magnetic resonance imaging (MRI)/photoacoustic (PA) bimodal molecular imaging properties. In summary, these developed multifunctional complexes have the potential to intensify immune activation to realize simultaneous cancer Radio/Chemo/Immunotherapy for clinical translation.

Reactive Oxygen Species Amplifier for Apoptosis-Ferroptosis Mediated High-Efficiency Radiosensitization of Tumors

Insufficient reactive oxygen species (ROS) production and radioresistance have consistently contributed to the failure of radiotherapy (RT). The development of a biomaterial capable of activating ROS-induced apoptosis and ferroptosis is a potential strategy to enhance RT sensitivity. To achieve precision and high-efficiency RT, the theranostic nanoplatform Au/Cu nanodots (Au/CuNDs) were designed for dual-mode imaging, amplifying ROS generation, and inducing apoptosis-ferroptosis to sensitize RT. A large amount of ROS is derived from three aspects: (1) When exposed to ionizing radiation, Au/CuNDs effectively absorb photons and emit various electrons, which can interact with water to produce ROS. (2) Au/CuNDs act as a catalase-like to produce abundant ROS through Fenton reaction with hydrogen peroxide overexpressed of tumor cells. (3) Au/CuNDs deplete overexpressed glutathione, which causes the accumulation of ROS. Large amounts of ROS and ionizing radiation further lead to apoptosis by increasing DNA damage, and ferroptosis by enhancing lipid peroxidation, significantly improving the therapeutic efficiency of RT. Furthermore, Au/CuNDs serve as an excellent nanoprobe for high-resolution near-infrared fluorescence imaging and computed tomography of tumors. The promising dual-mode imaging performance shows their potential application in clinical cancer detection and imaging-guided precision RT, minimizing damage to adjacent normal tissues during RT. In summary, our developed theranostic nanoplatform integrates dual-mode imaging and sensitizes RT via ROS-activated apoptosis-ferroptosis, offering a promising prospect for clinical cancer diagnosis and treatment.

Application of nano-radiosensitizers in non-small cell lung cancer

Radiotherapy stands as a cornerstone in the treatment of numerous malignant tumors, including non-small cell lung cancer. However, the critical challenge of amplifying the tumoricidal effectiveness of radiotherapy while minimizing collateral damage to healthy tissues remains an area of significant research interest. Radiosensitizers, by methods such as amplifying DNA damage and fostering the creation of free radicals, play a pivotal role in enhancing the destructive impact of radiotherapy on tumors. Over recent decades, nano-dimensional radiosensitizers have emerged as a notable advancement. Their mechanisms include cell cycle arrest in the G2/M phase, combating tumor hypoxia, and others, thereby enhancing the efficacy of radiotherapy. This review delves into the evolving landscape of nanomaterials used for radiosensitization in non-small cell lung cancer. It provides insights into the current research progress and critically examines the challenges and future prospects within this burgeoning field.

Ataxia telangiectasia and Rad3-related (ATR) inhibition by VE-822 potently reversed 5-flourouracil resistance in colorectal cancer cells through targeting DNA damage response

BACKGROUND

VE-822 is a novel inhibitor of ATR, a key kinase involved in the DNA damage response pathway. The role of ATR inhibition in reversing drug resistance in various cancer types has been investigated. Therefore, this study investigated the effects of ATR inhibition by VE-822 on reversing 5-fluorouracil (5-FU) resistance in colorectal cancer cell line (Caco-2).

METHODS

Caco-2 and 5-FU resistance Caco-2 (Caco-2/5-FU) cells were treated with 5-FU and VE-822, alone and in combination. Cell proliferation and viability were assessed by MTT assay and Trypan Blue staining. P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) activities were measured by Rhodamine123 accumulation and uptake assay. The mRNA levels of P-gp, MRP-1, ataxia telangiectasia and Rad3-related (ATR) and checkpoint kinase 1 (CHK1) were measured by qRT-PCR. Western blot was used to measure the protein levels of P-gp, MRP-1, γ-H2AX, ATR and CHK1 in cells. 8-Oxo-2'-deoxyguanosine (8-oxo-dG) levels were determined via ELISA. Apoptosis was evaluated by ELISA death assay, DAPI staining and lactate dehydrogenase (LDH) assay.

RESULTS

The Caco-2/5-FU cells showed lower levels of 5-FU mediated proliferation inhibition in comparison to Caco-2 cells. VE-822 decreased the IC50 value of 5-FU on resistant cells. In addition, the expression levels and activity of P-gp and MRP-1 were significantly decreased in resistant cells treated with VE-822 (P < 0.05). The combination of 5-FU and VE-822 increased apoptosis in Caco-2/5-FU cells by downregulating CHK1 and ATR and upregulating γ-H2AX and 8-oxo-dG.

CONCLUSION

The simultaneous treatment of resistant colorectal cancer cells with 5-FU and ATR inhibitor, VE-822, was demonstrated to be effective in reversing drug resistance and potentiating 5-FU mediated anticancer effects via targeting DNA damage.

Interaction of low-energy electrons with radiosensitizers

We provide an experimentalist's perspective on the present state-of-the-art in the studies of low-energy electron interactions with common radiosensitizers, including compounds used in combined chemo-radiation therapy and their model systems. Low-energy electrons are important secondary species formed during the interaction of ionizing radiation with matter. Their role in the radiation chemistry of living organisms has become an important topic for more than 20 years. With the increasing number of works and reviews in the field, we would like to focus here on a very narrow area of compounds that have been shown to have radio-sensitizing properties on the one hand, and high reactivity towards low-energy electrons on the other hand. Gas phase experiments studying electron attachment to isolated molecules and environmental effects on reaction dynamics are reviewed for modified DNA components, nitroimidazoles, and organometallics. In the end, we provide a perspective on the future directions that may be important for transferring the fundamental knowledge about the processes induced by low-energy electrons into practice in the field of rational design of agents for concomitant chemo-radiation therapy.

Coumarin-transition metal complexes with biological activity: current trends and perspectives

Coumarin (2H-1-benzopyran-2-one) presents the fundamental structure of an enormous class of biologically active compounds of natural, semi-synthetic, and synthetic origin. Extensive efforts are continually being put into the research and development of coumarin derivatives with medicinal properties by the broad scientific community. Transition metal coordination compounds with potential biological activity are a "hot topic" in the modern search for novel drugs. Complexation with transition metals can enhance the physiological effect of a molecule, modify its safety profile, and even imbue it with novel attributes of interest in the fields of medicine and pharmacy. The present review aims to inform the reader of the latest developments in the search for coumarin transition metal complexes with biological activity, their potential applications, and structure-activity relationships, where such can be elucidated. Each section of the present review addresses a certain kind of biological activity (antiproliferative, antioxidant, antimicrobial, etc.), explores the most recent discoveries in the field, and, at the same time, tries to offer useful perspectives for potential future investigations.

Radiometal-Labeled Photoactivatable Pt(IV) Anticancer Complex for Theranostic Phototherapy

A novel photoactivatable Pt(IV) diazido anticancer agent, Pt-succ-DFO, bearing a pendant deferoxamine (DFO) siderophore for radiometal chelation, has been synthesized for the study of its in vivo behavior with radionuclide imaging. Pt-succ-DFO complexation of Fe(III) and Ga(III) ions yielded new heterobimetallic complexes that maintain the photoactivation properties and photocytotoxicity of the parent Pt complex in human cancer cell lines. Radiolabeled Pt-succ-DFO-68Ga (t1/2 = 68 min, positron emitter) was readily prepared under mild conditions and was stable in the dark upon incubation with human serum. PET imaging of Pt-succ-DFO-68Ga in healthy mice revealed a promising biodistribution profile with rapid renal excretion and limited organ accumulation, implying that little off-target uptake is expected for this class of agents. Overall, this research provides the first in vivo imaging study of the whole-body distribution of a photoactivatable Pt(IV) azido anticancer complex and illustrates the potential of radionuclide imaging as a tool for the preclinical development of novel light-activated agents.

Sonocatalytic cancer therapy: theories, advanced catalysts and system design

Treating cancer remains one of the most formidable challenges in modern medicine, with traditional treatment options often being limited by poor therapeutic outcomes and unacceptable side effects. Nanocatalytic therapy activates tumor-localized catalytic reactions in situ via nontoxic or minimally toxic nanocatalysts responding to unique cues from the tumor microenvironment or external stimuli. In particular, sonocatalytic cancer therapy is a promising approach that has emerged as a potential solution to this problem through the combination of ultrasound waves and catalytic materials to selectively target and destroy cancer cells. Compared to light, ultrasound exhibits higher spatial precision, lower energy attenuation, and superior tissue penetrability, furnishing more energy to catalysts. Multidimensional modulation of nanocatalyst structures and properties is pivotal to maximizing catalytic efficiency given constraints in external stimulative energy as well as substrate types and levels. In this review, we discuss the various theories and mechanisms underlying sonocatalytic cancer therapy, as well as advanced catalysts that have been developed for this application. Additionally, we explore the design of sonocatalytic cancer therapy systems, including the use of heterojunction catalysts and the optimal conditions for achieving maximum therapeutic effects. Finally, we highlight the potential benefits of sonocatalytic cancer therapy over traditional cancer treatments, including its noninvasive nature and lower toxicity.

One Stone, Three Birds: Multifunctional Nanodots as "Pilot Light" for Guiding Surgery, Enhanced Radiotherapy, and Brachytherapy of Tumors

Surgery, radiotherapy (RT), and brachytherapy are crucial treatments for localized deep tumors. However, imprecise tumor location often leads to issues such as positive surgical margins, extended radiotherapy target volumes, and radiation damage to healthy tissues. Reducing side effects in healthy tissue and enhancing RT efficacy are critical challenges. To address these issues, we developed a multifunctional theranostic platform using Au/Ag nanodots (Au/AgNDs) that act as a "pilot light" for real-time guided surgery, high-efficiency RT, and brachytherapy, achieving a strategy of killing three birds with one stone. First, dual-mode imaging of Au/AgNDs enabled precision RT, minimizing damage to adjacent normal tissue during X-ray irradiation. Au/AgNDs enhanced ionizing radiation energy deposition, increased intracellular reactive oxygen species (ROS) generation, regulated the cell cycle, promoted DNA damage formation, and inhibited DNA repair in tumor cells, significantly improving RT efficacy. Second, in brachytherapy, precise guidance provided by dual-mode imaging addressed challenges related to non-visualization of existing interstitial brachytherapy and multiple adjustments of insertion needle positions. Meanwhile, the effect of brachytherapy was improved. Third, the excellent fluorescence imaging of Au/AgNDs accurately distinguished tumors from normal tissue, facilitating their use as a powerful tool for assisting surgeons during tumor resection. Taken together, our multifunctional theranostic platform offers real-time guidance for surgery and high-efficiency RT, and improves brachytherapy precision, providing a novel strategy and vision for the clinical diagnosis and treatment of cancer.

Bi-HPDO3A as a novel contrast agent for X-ray computed tomography

A new bismuth-based CT agent was synthesized through a facile synthesis strategy. The in vitro stability, toxicity and CT performance were evaluated. The in vivo imaging performance was investigated using three different doses (0.5, 1.2 and 5 mmol/kg) and the result obtained at 1.2 mmol/kg was compared with the clinically approved CT agent iopamidol at the same dosage.

Bi2-xMnxO3 Nanospheres Engaged Radiotherapy with Amplifying DNA Damage

Radiotherapy efficacy was greatly limited by hypoxia and overexpression of glutathione (GSH) in the tumor microenvironment (TME), which maintained the immunosuppressive microenvironment and promoted DNA repair. In this work, 4T1 cell membrane-coated Bi_2-xMn_xO₃ nanospheres have been achieved via a facile protocol, which showed enhanced therapeutic efficacy for a combination of radiotherapy and immunotherapy. Bi_2-xMn_xO₃ nanospheres showed appreciable performance in generating O₂ in situ and depleting GSH to amplify DNA damage and remodel the tumor immunosuppressive microenvironment, thus enhancing radiotherapy efficacy. Cancer cell membrane-coated Bi_2-xMn_xO₃ nanospheres (T@BM) prolonged blood circulation time and enriched the accumulation of the materials in the tumor. Meanwhile, the released Mn²⁺ could activate STING pathway-induced immunotherapy, resulting in the immune infiltration of CD8⁺ T cells on in situ mammary tumors and the inhibition of pulmonary nodules. As a result, approximately 1.9-fold recruitment of CD8⁺ T cells and 4.0-fold transformation of mature DC cells were observed compared with the phosphate-buffered saline (PBS) group on mammary tumors (in situ). In particular, the number of pulmonary nodules significantly decreased and the proliferation of pulmonary metastatic lesions was substantially inhibited, which provided a longer survival period. Therefore, T@BM exhibited great potential for the treatment of 4T1 tumors in situ and lung metastasis.

Prognostic Impact of Dihydropyrimidine Dehydrogenase Germline Variants in Unresectable Non-Small Cell Lung Cancer Patients Treated with Platin-Based Chemotherapy

Platin-based chemotherapy is the standard treatment for patients with non-small cell lung cancer (NSCLC). However, resistance to this therapy is a major obstacle in successful treatment. In this study, we aimed to investigate the impact of several pharmacogenetic variants in patients with unresectable NSCLC treated with platin-based chemotherapy. Our results showed that DPYD variant carriers had significantly shorter progression-free survival and overall survival compared to DPYD wild-type patients, whereas DPD deficiency was not associated with a higher incidence of high-grade toxicity. For the first time, our study provides evidence that DPYD gene variants are associated with resistance to platin-based chemotherapy in NSCLC patients. Although further studies are needed to confirm these findings and explore the underlying mechanisms of this association, our results suggest that genetic testing of DPYD variants may be useful for identifying patients at a higher risk of platin-based chemotherapy resistance and might be helpful in guiding future personalized treatment strategies in NSCLC patients.

A MOF-Based Potent Ferroptosis Inducer for Enhanced Radiotherapy of Triple Negative Breast Cancer

Radiotherapy (RT) is one of the important clinical treatments for local control of triple-negative breast cancer (TNBC), but radioresistance still exists. Ferroptosis has been recognized as a natural barrier for cancer progression and represents a significant role of RT-mediated anticancer effects, while the simultaneous activation of ferroptosis defensive system during RT limits the synergistic effect between RT and ferroptosis. Herein, we engineered a tumor microenvironment (TME) degradable nanohybrid with a dual radiosensitization manner to combine ferroptosis induction and high-Z effect based on metal-organic frameworks for ferroptosis-augmented RT of TNBC. The encapsulated l-buthionine-sulfoximine (BSO) could inhibit glutathione (GSH) biosynthesis for glutathione peroxidase 4 (GPX4) inactivation to break down the ferroptosis defensive system, and the delivered ferrous ions could act as a powerful ferroptosis executor via triggering the Fenton reaction; the combination of them induces potent ferroptosis, which could synergize with the surface decorated Gold (Au) NPs-mediated radiosensitization to improve RT efficacy. In vivo antitumor results revealed that the nanohybrid could significantly improve the therapeutic efficacy and antimetastasis efficiency based on the combinational mechanism between ferroptosis and RT. This work thus demonstrated that combining RT with efficient ferroptosis induction through nanotechnology was a feasible and promising strategy for TNBC treatment.

Anti-Cancer and Radio-Sensitizing Properties of New Bimetallic (N-Heterocyclic Carbene)-Amine-Pt(II) Complexes

Bioactive NHC-transition metal complexes have shown promise as anti-cancer agents, but their potential use as radiosensitizers has been neglected so far. We disclose here a new series of bimetallic platinum(II) complexes displaying NHC-type bridging ligands, (bis-NHC)[trans-Pt(RNH₂)I₂]₂, that have been synthesized via a simple, two-step procedure. They display cytotoxicity in the micromolar range on cancerous cell lines, accumulate in cells, and bind to genomic DNA, by inducing DNA damages. Notably, these bimetallic complexes demonstrate significant radiosensitizing effects on both ovarian cells A2780 and nonsmall lung carcinoma cells H1299. Further investigations revealed that bimetallic species make irradiation-induced DNA damages more persistent by inhibiting repair mechanisms. Indeed, a higher and persistent accumulation of both γ-H2AX and 53BP1 foci post-irradiation was detected, in the presence of the NHC-Pt complexes. Overall, we provide the first in vitro evidence for the radiosensitizing properties of NHC-platinum complexes, which suggests their potential use in combined chemo-radio therapy protocols.

Discovery of Ruthenium(II) Metallocompound and Olaparib Synergy for Cancer Combination Therapy

Synergistic drug combinations can extend the use of poly(ADP-ribose) polymerase inhibitors (PARPi) such as Olaparib to BRCA-proficient tumors and overcome acquired or de novo drug resistance. To identify new synergistic combinations for PARPi, we screened a "micro-library" comprising a mix of commercially available drugs and DNA-binding ruthenium(II) polypyridyl complexes (RPCs) for Olaparib synergy in BRCA-proficient triple-negative breast cancer cells. This identified three hits: the natural product Curcumin and two ruthenium(II)-rhenium(I) polypyridyl metallomacrocycles. All combinations identified were effective in BRCA-proficient breast cancer cells, including an Olaparib-resistant cell line, and spheroid models. Mechanistic studies indicated that synergy was achieved via DNA-damage enhancement and resultant apoptosis. Combinations showed low cytotoxicity toward non-malignant breast epithelial cells and low acute and developmental toxicity in zebrafish embryos. This work identifies RPC metallomacrocycles as a novel class of agents for cancer combination therapy and provides a proof of concept for the inclusion of metallocompounds within drug synergy screens.

Platinum(II) 5-substituted-8-hydroxyquinoline coordination compounds induces mitophagy-mediated apoptosis in A549/DDP cancer cells

For the first time, two new mononuclear platinum(II) coordination compounds, [Pt(L1)(DMSO)Cl] (PtL1) and [Pt(L2)(DMSO)Cl] (PtL2) with the 5-(ethoxymethyl)-8-hydroxyquinoline hydrochloride (H-L1) and 5-bromo-8-hydroxyquinoline (H-L2) have been synthesized and characterized. The cytotoxic activity of PtL1 and PtL2 were screened in both healthy HL-7702 cell line and cancer cell lines, human lung adenocarcinoma A549 cancer cells and cisplatin-resistant lung adenocarcinoma A549/DDP cancer cells (A549R), and were compared to that of the H-L1, H-L2, H-L3 ligands and 8-hydroxyquinoline (H-L3) platinum(II) complex [Pt(L3)(DMSO)Cl] (PtL3). MTT results showed that PtL1 bearing one deprotonated L1 ligand against A549R was more potent by 8.8-48.6 fold than that of PtL2 and PtL3 complexes but was more selective toward healthy HL-7702 cells. In addition, PtL1 and PtL3 overcomes tumour drug resistance by significantly inducing mitophagy and causing the change of the related proteins expression, which leads to cell apoptosis. Moreover, the inhibitory effect of PtL1 on A549 xenograft tumour was 68.2%, which was much higher than that of cisplatin (cisPt, ca. 50.0%), without significantly changing nude mice weight in comparison with the untreated group. This study helps to explore the potential of the platinum(II) 5-substituted-8-hydroxyquinoline coordination compounds for the new Pt-resistant cancer therapy.

Combining Copper and Zinc into a Biosensor for Anti-Chemoresistance and Achieving Osteosarcoma Therapeutic Efficacy

Due to its built-up chemoresistance after prolonged usage, the demand for replacing platinum in metal-based drugs (MBD) is rising. The first MBD approved by the FDA for cancer therapy was cisplatin in 1978. Even after nearly four and a half decades of trials, there has been no significant improvement in osteosarcoma (OS) therapy. In fact, many MBD have been developed, but the chemoresistance problem raised by platinum remains unresolved. This motivates us to elucidate the possibilities of the copper and zinc (CuZn) combination to replace platinum in MBD. Thus, the anti-chemoresistance properties of CuZn and their physiological functions for OS therapy are highlighted. Herein, we summarise their chelators, main organic solvents, and ligand functions in their structures that are involved in anti-chemoresistance properties. Through this review, it is rational to discuss their ligands' roles as biosensors in drug delivery systems. Hereafter, an in-depth understanding of their redox and photoactive function relationships is provided. The disadvantage is that the other functions of biosensors cannot be elaborated on here. As a result, this review is being developed, which is expected to intensify OS drugs with higher cure rates. Nonetheless, this advancement intends to solve the major chemoresistance obstacle towards clinical efficacy.

Alleviating the hypoxic tumor microenvironment with MnO2-coated CeO2 nanoplatform for magnetic resonance imaging guided radiotherapy

BACKGROUND

Radiotherapy is a commonly used tool in clinical practice to treat solid tumors. However, due to the unique microenvironment inside the tumor, such as high levels of GSH, overexpressed H₂O₂ and hypoxia, these factors can seriously affect the effectiveness of radiotherapy.

RESULTS

Therefore, to further improve the efficiency of radiotherapy, a core-shell nanocomposite CeO₂-MnO₂ is designed as a novel radiosensitizer that can modulate the tumor microenvironment (TME) and thus improve the efficacy of radiation therapy. CeO₂-MnO₂ can act as a radiosensitizer to enhance X-ray absorption at the tumor site while triggering the response behavior associated with the tumor microenvironment. According to in vivo and in vitro experiments, the nanoparticles aggravate the killing effect on tumor cells by generating large amounts of ROS and disrupting the redox balance. In this process, the outer layer of MnO₂ reacts with GSH and H₂O₂ in the tumor microenvironment to generate ROS and release oxygen, thus alleviating the hypoxic condition in the tumor area. Meanwhile, the manganese ions produced by degradation can enhance T1-weighted magnetic resonance imaging (MRI). In addition, CeO₂-MnO₂, due to its high atomic number oxide CeO₂, releases a large number of electrons under the effect of radiotherapy, which further reacts with intracellular molecules to produce reactive oxygen species and enhances the killing effect on tumor cells, thus having the effect of radiotherapy sensitization. In conclusion, the nanomaterial CeO₂-MnO₂, as a novel radiosensitizer, greatly improves the efficiency of cancer radiation therapy by improving the lack of oxygen in tumor and responding to the tumor microenvironment, providing an effective strategy for the construction of nanosystem with radiosensitizing function.

CONCLUSION

In conclusion, the nanomaterial CeO₂-MnO₂, as a novel radiosensitizer, greatly improves the efficiency of cancer radiation therapy by improving the lack of oxygen in tumor and responding to the tumor microenvironment, providing an effective strategy for the construction of nanosystems with radiosensitizing function.

Novel strategies for tumor radiosensitization mediated by multifunctional gold-based nanomaterials

Radiotherapy (RT) is one of the most effective and commonly used cancer treatments for malignant tumors. However, the existing radiosensitizers have a lot of side effects and poor efficacy, which limits the curative effect and further application of radiotherapy. In recent years, emerging nanomaterials have shown unique advantages in enhancing radiosensitization. In particular, gold-based nanomaterials, with high X-ray attenuation capacity, good biocompatibility, and promising chemical, electronic and optical properties, have become a new type of radiotherapy sensitizer. In addition, gold-based nanomaterials can be used as a carrier to load a variety of drugs and immunosuppressants; in particular, its photothermal therapy, photodynamic therapy and multi-mode imaging functions aid in providing excellent therapeutic effect in coordination with RT. Recently, many novel strategies of radiosensitization mediated by multifunctional gold-based nanomaterials have been reported, which provides a new idea for improving the efficacy and reducing the side effects of RT. In this review, we systematically summarize the recent progress of various new gold-based nanomaterials that mediate radiosensitization and describe the mechanism. We further discuss the challenges and prospects in the field. It is hoped that this review will help researchers understand the latest progress of gold-based nanomaterials for radiosensitization, and encourage people to optimize the existing methods or explore novel approaches for radiotherapy.

Mitochondrial dysfunction-targeted nanosystems for precise tumor therapeutics

Mitochondria play critical roles in the regulation of the proliferation and apoptosis of cancerous cells. Targeted induction of mitochondrial dysfunction in cancer cells by multifunctional nanosystems for cancer treatment has attracted increasing attention in the past few years. Numerous therapeutic nanosystems have been designed for precise tumor therapy by inducing mitochondrial dysfunction, including reducing adenosine triphosphate, breaking redox homeostasis, inhibiting glycolysis, regulating proteins, membrane potential depolarization, mtDNA damage, mitophagy dysregulation and so on. Understanding the mechanisms of mitochondrial dysfunction would be helpful for efficient treatment of diseases and accelerating the translation of these therapeutic strategies into the clinic. Then, various strategies to construct mitochondria-targeted nanosystems and induce mitochondrial dysfunction are summarized, and the recent research progress regarding precise tumor therapeutics is highlighted. Finally, the major challenges and an outlook in this rapidly developing field are discussed. This review is expected to inspire further development of novel mitochondrial dysfunction-based strategies for precise treatments of cancer and other human diseases.

Synergy of ruthenium metallo-intercalator, [Ru(dppz)2(PIP)]2+, with PARP inhibitor Olaparib in non-small cell lung cancer cells

Poly(ADP-ribose) polymerase (PARP) are critical DNA repair enzymes that are activated as part of the DNA damage response (DDR). Although inhibitors of PARP (PARPi) have emerged as small molecule drugs and have shown promising therapeutic effects, PARPi used as single agents are clinically limited to patients with mutations in germline breast cancer susceptibility gene (BRCA). Thus, novel PARPi combination strategies may expand their usage and combat drug resistance. In recent years, ruthenium polypyridyl complexes (RPCs) have emerged as promising anti-cancer candidates due to their attractive DNA binding properties and distinct mechanisms of action. Previously, we reported the rational combination of the RPC DNA replication inhibitor [Ru(dppz)₂(PIP)]²⁺ (dppz = dipyrido[3,2-a:2',3'-c]phenazine, PIP = 2-(phenyl)-imidazo[4,5-f][1,10]phenanthroline), "Ru-PIP", with the PARPi Olaparib in breast cancer cells. Here, we expand upon this work and examine the combination of Ru-PIP with Olaparib for synergy in lung cancer cells, including in 3D lung cancer spheroids, to further elucidate mechanisms of synergy and additionally assess toxicity in a zebrafish embryo model. Compared to single agents alone, Ru-PIP and Olaparib synergy was observed in both A549 and H1975 lung cancer cell lines with mild impact on normal lung fibroblast MRC5 cells. Employing the A549 cell line, synergy was confirmed by loss in clonogenic potential and reduced migration properties. Mechanistic studies indicated that synergy is accompanied by increased double-strand break (DSB) DNA damage and reactive oxygen species (ROS) levels which subsequently lead to cell death via apoptosis. Moreover, the identified combination was successfully able to inhibit the growth of A549 lung cancer spheroids and acute zebrafish embryos toxicity studies revealed that this combination showed reduced toxicity compared to single-agent Ru-PIP.

Antioxidant conjugated metal complexes and their medicinal applications

Antioxidants are naturally available and man-made substances have the ability to protect cells from damage due to a number of intracellular redox activities. Moreover, Antioxidants such as α-lipoic acid, curcumin and catechin are good anticancer agents. In recent years, the usage of metal complexes as therapeutic agents is gaining importance due to their useful biological properties. Most of the metal ions act as the essential components in building drug molecules that serve as medicines for cancer and neurodegenerative diseases. In particular, metals like copper, gold, ruthenium, and platinum have adequate anticancer properties at both micro- and nano-levels. Hence, conjugation of antioxidants with metals and metal-based compounds results in hybrid bioactive materials with improved anticancer properties. In this chapter, medicinal applications of antioxidant conjugated metal complexes are reviewed and discussed.

Flexible polymeric patch based nanotherapeutics against non-cancer therapy

Flexible polymeric patches find widespread applications in biomedicine because of their biological and tunable features including excellent patient compliance, superior biocompatibility and biodegradation, as well as high loading capability and permeability of drug. Such polymeric patches are classified into microneedles (MNs), hydrogel, microcapsule, microsphere and fiber depending on the formed morphology. The combination of nanomaterials with polymeric patches allows for improved advantages of increased curative efficacy and lowered systemic toxicity, promoting on-demand and regulated drug administration, thus providing the great potential to their clinic translation. In this review, the category of flexible polymeric patches that are utilized to integrate with nanomaterials is briefly presented and their advantages in bioapplications are further discussed. The applications of nanomaterials embedded polymeric patches in non-cancerous diseases were also systematically reviewed, including diabetes therapy, wound healing, dermatological disease therapy, bone regeneration, cardiac repair, hair repair, obesity therapy and some immune disease therapy. Alternatively, the limitations, latest challenges and future perspectives of such biomedical therapeutic devices are addressed.

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The most explored polymeric patches, such as microneedle, hydrogel, microsphere, microcapsule, and fiber are summarized.

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Polymeric patches integrated with a diversity of nanomaterials are systematically overviewed in non-cancer therapy.

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The future prospective for the development of polymeric patch based nanotherapeutics is discussed.

Ultrasmall zirconium carbide nanodots for synergistic photothermal-radiotherapy of glioma

Glioma is characterized by highly invasive, progressive, and lethal features. In addition, conventional treatments have been poorly effective in treating glioma. To overcome this challenge, synergistic therapies combining radiotherapy (RT) with photothermal therapy (PTT) have been proposed and extensively explored as a highly feasible cancer treatment strategy. Herein, ultrasmall zirconium carbide (ZrC) nanodots were successfully synthesized with high near-infrared absorption and strong photon attenuation for synergistic PTT-RT of glioma. ZrC-PVP nanodots with an average size of approximately 4.36 nm were prepared by the liquid exfoliation method and modified with the surfactant polyvinylpyrrolidone (PVP), with a satisfactory absorption and photothermal conversion efficiency (53.4%) in the near-infrared region. Furthermore, ZrC-PVP nanodots can also act as radiosensitizers to kill residual tumor cells after mild PTT due to their excellent photon attenuating ability, thus achieving a significant synergistic therapeutic effect by combining RT and PTT. Most importantly, both in vitro and in vivo experimental results further validate the high biosafety of ZrC-PVP NDs at the injected dose. This work systematically evaluates the feasibility of ZrC-PVP NDs for glioma treatment and provides evidence of the application of zirconium-based nanomaterials in photothermal radiotherapy.

Integrating the microneedles with carboplatin to facilitate the therapeutic effect of radiotherapy for skin cancers

In most skin cancer patients, excisional surgery is required to remove tumorous tissue. However, the risk of locoregional recurrence after surgery alone is relatively high, particularly for a locally advanced stage of melanoma. Therefore, additional adjuvant treatments, such as radiotherapy, can be used after surgery to inhibit recurrent melanoma after surgical removal. To enhance local radiotherapy, we present the combined X-ray radiation and radiosensitizers (carboplatin) through microneedles (MNs) to treat melanoma. The MNs could be beneficial to precisely delivering carboplatin into the sub-epidermal layer of the melanoma region and alleviate patients' fear and discomfort during the drug administration compared to the traditional local injection. The carboplatin was loaded into the tips of dissolving gelatin MNs (carboplatin-MNs) through the molding method. The results show gelatin MNs have sufficient mechanical strength and can successfully administer carboplatin into the skin. Both in vitro and in vivo studies suggest that carboplatin can enhance radiotherapy in melanoma treatment. With a combination of radiotherapy and carboplatin, the inhibition effect of carboplatin delivered into the B16F10 murine melanoma model through MNs administration (1.2 mg/kg) is equivalent to that through an intravenous route (5 mg/kg). The results demonstrate a promise of combined carboplatin and X-ray radiation treatment in treating melanoma by MNs administration.

A 2D Nanoradiosensitizer Enhances Radiotherapy and Delivers STING Agonists to Potentiate Cancer Immunotherapy

Despite potent preclinical antitumor activity, activation of stimulator of interferon genes (STING) has shown modest therapeutic effects in clinical studies. Many STING agonists, including 2',3'-cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), show poor pharmacokinetic properties for sustaining STING activation in tumors and achieving optimal antitumor efficacy. Improved delivery of STING agonists and their effective combination with other treatments are needed to enhance their therapeutic effects. Herein, a 2D nanoplatform, cGAMP/MOL, is reported via conjugating cGAMP to a nanoscale metal-organic layer (MOL) for simultaneous STING activation and radiosensitization. The MOL not only exhibits strong radiosensitization effects for enhanced cancer killing and induction of immunogenic cell death, but also retains cGAMP in tumors for sustained STING activation. Compared to free cGAMP, cGAMP/MOL elicits stronger STING activation and regresses local tumors upon X-ray irradiation. Further combination with an immune checkpoint inhibitor bridges innate and adaptive immune systems by activating the tumor microenvironment to elicit systemic antitumor responses.

DNA-cloaked nanoparticles for tumor microenvironment-responsive activation

Although progress has been made in developing tumor microenvironment-responsive delivery systems, the list of cargo-releasing stimuli remains limited. In this study, we report DNA nanothread-cloaked nanoparticles for reactive oxygen species (ROS)-rich tumor microenvironment-responsive delivery systems. ROS is well known to strongly induce DNA fragmentation via oxidative stress. As a model anticancer drug, hydrophobic omacetaxine was entrapped in branched cyclam ligand-modified nanoparticles (BNP). DNA nanothreads were prepared by rolling-circle amplification and complexed to BNP, yielding DNA nanothread-cloaked BNP (DBNP). DBNP was unmasked by DNA nanothread-degrading ROS and culture supernatants of LNCaP cells. The size and zeta potential of DBNP were changed by ROS. In ROS^high LNCaP cells, but not in ROS^low fibroblast cells, the uptake of DBNP was higher than that of other nanoparticles. Molecular imaging revealed that DBNP exhibited greater distribution to tumor tissues, compared to other nanoparticles. Ex vivo mass spectrometry-based imaging showed that omacetaxine metabolites were distributed in tumor tissues of mice treated with DBNP. Intravenous administration of DBNP reduced the tumor volume by 80% compared to untreated tumors. Profiling showed that omacetaxine treatment altered the transcriptional profile. These results collectively support the feasibility of using polymerized DNA-masked nanoparticles for selective activation in the ROS-rich tumor microenvironment.

Small Molecules and Immunotherapy Agents for Enhancing Radiotherapy in Glioblastoma

Glioblastoma (GBM) is an aggressive primary brain tumor that is associated with a poor prognosis and quality of life. The standard of care has changed minimally over the past two decades and currently consists of surgery followed by radiotherapy (RT), concomitant and adjuvant temozolomide, and tumor treating fields (TTF). Factors such as tumor hypoxia and the presence of glioma stem cells contribute to the radioresistant nature of GBM. In this review, we discuss the current treatment modalities, mechanisms of radioresistance, and studies that have evaluated promising radiosensitizers. Specifically, we highlight small molecules and immunotherapy agents that have been studied in conjunction with RT in clinical trials. Recent preclinical studies involving GBM radiosensitizers are also discussed.

Antitumor Applications of Photothermal Agents and Photothermal Synergistic Therapies

As a new tumor treatment strategy, photothermal therapy (PTT) has the advantages of accuracy, ease of administration, a high efficiency and low side effects. Photothermal transduction agents (PTAs) are the key factor which play an important role in PTT. The mechanism of PTT is discussed in detail. The photothermal conversion efficiency (PCE) can be improved by increasing the light absorption and reducing the light scattering of photothermal conversion agents. Additionally, non-radiative relaxation path attenuation can also promote energy conversion to obtain a higher value in terms of PCE. The structure and photothermal characteristics of various kinds of PTAs (metal materials, carbon-based nanomaterials, two-dimensional nanomaterials, and organic materials) were compared and analyzed. This paper reviews the antitumor applications of photothermal synergistic therapies, including PTT combined with immunotherapy, chemotherapy, and photodynamic therapy. This review proposes that these PTAs promote the development of photothermal synergistic therapies and have a great potential in the application of tumor treatment.

Nanomaterials Based on Functional Polymers for Sensitizing Cancer Radiotherapy

Despite being the mainstay treatment for many types of cancer in clinic, radiotherapy is undertaking great challenges in overcoming a series of limitations. Radiosensitizers are promising agents capable of depositing irradiation energy and generating free radicals to enhance the radiosensitivity of tumor cells. Combining radiosensitizers with functional polymer-based nanomaterials holds great potential to improve biodistribution, circulation time, and stability in vivo. The derived polymeric nano-radiosensitizers can significantly improve the efficiency of tumor targeting and radiotherapy, and reduce the side effect to healthy tissues. In this review, we provide an overview of functional polymer-based nanomaterials for radiosensitization in recent years. Particular emphases are given to the action mechanisms, drug loading methods, targeting efficiencies, the impact on therapeutic effects and biocompatibility of various radiosensitizing polymers, which are classified as polymeric micelles, dendrimers, polymeric nanospheres, nanoscale coordination polymers, polymersomes, and nanogels. The challenges and outlooks of polymeric nano-radiosensitizers are also discussed. This article is protected by copyright. All rights reserved.

Recent advances in noble metal complex based photodynamic therapy

Photodynamic therapy (PDT) utilizes light-activated photosensitizers (PSs) to generate toxic species for therapeutics. It has become an emerging solution for cancer treatment because of its specific spatiotemporal selectivity and minimal invasiveness. Noble metal (Ru, Ir and Pt) complexes are of increasing interest as photosensitizers for their excellent photophysical, photochemical, and photobiological properties. In this review, we highlight recent advancements in the development of noble metal complex photosensitizers for PDT during the last 5 years. We will summarize the design strategies of noble metal complexes for efficient and precise PDT, including increasing the light penetration depth, reducing the oxygen-dependent nature and improving target ability. Finally, we summarize recent efforts for the development of noble-based PSs and discuss the limitations of such PSs in clinical application and future perspectives in this field, such as the combination of PDT with other treatment modalities.

Radiation-induced prodrug activation: extending combined modality therapy for some solid tumours

Combined chemoradiotherapy is the standard of care for locally advanced solid tumours. However, systemic toxicity may limit the delivery of planned chemotherapy. New approaches such as radiation-induced prodrug activation might diminish systemic toxicity, while retaining anticancer benefit. Organic azides have recently been shown to be reduced and activated under hypoxic conditions with clinically relevant doses of radiotherapy, uncaging pazopanib and doxorubicin in preclinical models with similar efficacy as the drug, but lower systemic toxicity. This approach may be relevant to the chemoradiation of glioblastoma and other solid tumours and offers potential for switching on drug delivery from implanted devices. The inclusion of reporters to confirm drug activation, avoidance of off-target effects and synchronisation of irradiation with optimal intratumoral drug concentration will be critical. Further preclinical validation studies of this approach should be encouraged.

Antitumor Activity of Palladium(II) Complexes on DU-145 Cell Line in Vitro

In the area of non-platinum complexes, various complexes containing gold, copper, ruthenium, and palladium have shown a strong cytotoxic effect on different cancer cell lines. The aim of our study was to examine the cytotoxicity of the Pd(II) complexes (C1-C5) and the corresponding ligands (L1-L5) on the DU-145 prostate cancer cell line. Also, due to its clinical application, the cytotoxicity of cisplatin has been examined. Our findings showed that C1- C5 complexes and cisplatin show dose-dependent and strong cytotoxic effects against the DU-145 cell line in vitro. Furthermore, the results demonstrated that early apoptosis was induced by all five Pd(II) complexes. Also, the results showed that complexes C1, C3, and C5 induced G0/G1 phase arrest on DU- 145 cells. Pd(II) complex C2 induced S phase arrest, while C4 complex induced G2/M phase arrest on cancer cells. Additionally, all tested complexes significantly reduced the amount of antiapoptotic protein Bcl-2. Also, there was a significant increase in the concentration of proapoptotic Bax protein in DU-145 cells treated C1-C5 complexes. The results of our research demonstrated that Pd(II) complexes induced apoptosis via the mitochondrial pathway. Thus, it is crucial to further investigate the cytotoxicity of these Pd(II) complexes in vivo. Complex C2 might be a good candidate for a new generation of anticancer drugs.

Engineering Radiosensitizer-Based Metal-Phenolic Networks Potentiate STING Pathway Activation for Advanced Radiotherapy

Radiotherapy, a mainstay of first-line cancer treatment, suffers from its high-dose radiation-induced systemic toxicity and radioresistance caused by the immunosuppressive tumor microenvironment. The synergy between radiosensitization and immunomodulation may overcome these obstacles for advanced radiotherapy. Here, the authors propose a radiosensitization cooperated with stimulator of interferon genes (STING) pathway activation strategy by fabricating a novel lanthanide-doped radiosensitizer-based metal-phenolic network, NaGdF₄ :Nd@NaLuF₄ @PEG-polyphenol/Mn (DSPM). The amphiphilic PEG-polyphenol successfully coordinates with NaGdF₄ :Nd@NaLuF₄ (radiosensitizer) and Mn²⁺ via robust metal-phenolic coordination. After cell internalization, the pH-responsive disassembly of DSPM triggers the release of their payloads, wherein radiosensitizer sensitizes cancer cells to X-ray and Mn²⁺ promote STING pathway activation. This radiosensitizer-based DSPM remarkably benefits dendritic cell maturation, anticancer therapeutics in primary tumors, accompanied by robust systemic immune therapeutic performance against metastatic tumors. Therefore, a powerful radiosensitization with STING pathway activation mediated immunostimulation strategy is highlighted here to optimize cancer radiotherapy.

Mössbauer effect using 57Fe-ferrabisdicarbollide ([o-57FESAN]-): a glance into the potential of a low-dose approach for glioblastoma radiotherapy

Although a variety of cancers is initially susceptible to chemotherapy, they eventually develop multi-drug resistance. To overcome this situation, more effective and selective treatments are necessary by using anti-tumour agents...

Intracellular Amplifiers of Reactive Oxygen Species Affecting Mitochondria as Radiosensitizers

Radiotherapy (RT) efficacy can be improved by using radiosensitizers, i.e., drugs enhancing the effect of ionizing radiation (IR). One of the side effects of RT includes damage of normal tissue in close proximity to the treated tumor. This problem can be solved by applying cancer specific radiosensitizers. N-Alkylaminoferrocene-based (NAAF) prodrugs produce reactive oxygen species (ROS) in cancer cells, but not in normal cells. Therefore, they can potentially act as cancer specific radiosensitizers. However, early NAAF prodrugs did not exhibit this property. Since functional mitochondria are important for RT resistance, we assumed that NAAF prodrugs affecting mitochondria in parallel with increasing intracellular ROS can potentially exhibit synergy with RT. We applied sequential Cu+-catalyzed alkyne-azide cycloadditions (CuAAC) to obtain a series of NAAF derivatives with the goal of improving anticancer efficacies over already existing compounds. One of the obtained prodrugs (2c) exhibited high anticancer activity with IC50 values in the range of 5-7.1 µM in human ovarian carcinoma, Burkitt's lymphoma, pancreatic carcinoma and T-cell leukemia cells retained moderate water solubility and showed cancer specificity. 2c strongly affects mitochondria of cancer cells, leading to the amplification of mitochondrial and total ROS production and thus causing cell death via necrosis and apoptosis. We observed that 2c acts as a radiosensitizer in human head and neck squamous carcinoma cells. This is the first demonstration of a synergy between the radiotherapy and NAAF-based ROS amplifiers.

Computational Study of Photochemical Relaxation Pathways of Platinum(II) Complexes

A series of functional platinum(II) complexes (Pt1-Pt3), which present high activity in four-photon absorption, in vivo imaging, and precise cancer therapy, as previously reported by the experimental work of Zhang et al. (Inorg. Chem. 2021, 60, 2362-2371), are computationally investigated in the article. We find that after the complex goes through four-photon absorption to the S₁ state, it undergoes intersystem crossing to the T₂ state and eventually reaches the T₁ state through internal conversion. On the T₁ state, both radiative and nonradiative decay to S₀ exit. The radiative decay forms the basis for the phosphorescence imaging in tissues as reported in the original paper. In addition, the nonradiative decay can simultaneously generate cytotoxic singlet oxygen by the excited energy transfer process, also known as triplet oxygen's quenching of triplet states. We conclude that the phosphorescence property as well as the photosensitizer character jointly bring high activity of in vivo imaging and photodynamic therapy to these complexes.

Metal complexes against breast cancer stem cells

With the highest incidence, breast cancer is the leading cause of cancer deaths among women in the world. Tumor metastasis is the major contributor of high mortality in breast cancer, and the existence of cancer stem cells (CSCs) has been proven to be the cause of tumor metastasis. CSCs are a small proportion of tumor cells, and they are associated with self-renewal and tumorigenic potential. Given the significance of CSCs in tumor initiation, expansion, relapse, resistance, and metastasis, studies should investigate and discover effective anticancer agents that can not only inhibit the proliferation of differentiated tumor cells but also reduce the tumorigenic capability of CSCs. Thus, new therapies must be discovered to treat and prevent this severely hazardous disease of human beings. The success of platinum complexes in cancer treatment has laid the basic foundation for the utilization of metal complexes in the treatment of malignant cancers, in particular the highly aggressive triple-negative breast cancer. Importantly, metal complexes currently have diverse and versatile competences in the therapeutic targeting of CSCs. The anti-CSC properties provide a strong impetus for the development of novel metal-based compounds for the targeting of CSCs and treatment of chemotherapy-resistant and relapsed tumors. In this review, we provide the latest advances in metal complexes including platinum, ruthenium, osmium, iridium, manganese, cobalt, nickel, copper, zinc, palladium, and tin complexes against breast CSCs obtained over the past decade, with pertinent literature including those published until 2021.

Multifunctional MnO2-based nanoplatform-induced ferroptosis and apoptosis for synergetic chemoradiotherapy

Background: Radiosensitizers that can effectively consume glutathione provide broad prospects for enhancing the efficacy and reducing the side effects of radiotherapy. Aim: To explore the potential role of CuS@mSiO₂@MnO₂ nanocomposites in synergetic chemoradiotherapy. Methods: Nanocomposites were characterized by transmission electron microscopy, UV-Vis spectrometry and dynamic light scattering and were loaded with doxorubicin (DOX). The uptake and biodistribution of nanocomposites were observed by CCK8 assay, MRI and confocal laser scanning microscopy. The radiosensitization effect of nanocomposites and nanocomposites/DOX was assessed both in vitro and in vivo. Results: In vitro application of nanocomposites, with an average diameter of 30 nm and ζ-potential of 13.2 ± 0.4 mV, in combination with radiotherapy, depleted glutathione and induced ferroptosis and apoptosis. Nanocomposites/DOX exhibited tumor cell damage in vivo. Conclusion: We propose that this glutathione-depleting nanosystem could be a radiosensitizer as well as a drug transporter.

A transformable gold nanocluster aggregate-based synergistic strategy for potentiated radiation/gene cancer therapy

Nano-radiosensitizers provide a powerful tool for cancer radiation therapy. However, their limited tumor retention/penetration and the inherent or adaptive radiation resistance of tumor cells hamper the clinical success of radiation therapy. Herein, we report a synergistic strategy for potentiated cancer radiation/gene therapy based on transformable gold nanocluster aggregates loaded with antisense oligonucleotide-targeting survivin mRNA (named AuNC-ASON). AuNC-ASON exhibited acidic pH-triggered structure splitting from a gold nanocluster aggregate (around 80 nm) to gold nanocluster (<2 nm), leading to the tumor microenvironment-responsive size transformation of the nano-radiosensitizer and activated release of the loaded antisense oligonucleotides to perform gene silencing. The in vitro experiments demonstrated that AuNC-ASON could amplify and improve the radio-sensitivity of tumor cells (the sensitization enhancement ratio was about 1.81) as a result of the synergistic effect of the transformable gold nanocluster radiosensitizer and survivin gene interference. Remarkably, the size transformation capability realized the high tumor retention/penetration and renal metabolism of AuNC-ASON in vivo and boosted the radio-susceptibility of cancer cells with the assistance of survivin gene interference, synergistically achieving potentiated tumor radiation/gene therapy. The proposed concept of transformable nano-radiosensitizer aggregate-based synergistic therapy can be utilized as a general strategy to guide the design of activatable multifunctional nanosystems for cancer theranostics.

Discovery of metal-based complexes as promising antimicrobial agents

The antimicrobial resistance (AMR) is an intractable problem for the world. Metal ions are essential for the cell process and biological function in microorganisms. Many metal-based complexes with the potential for releasing ions are more likely to be absorbed for their higher lipid solubility. Hence, this review highlights the clinical potential of organometallic compounds for the treatment of infections caused by bacteria or fungi in recent five years. The common scaffolds, including antimicrobial peptides, N-heterocyclic carbenes, Schiff bases, photosensitive-grand-cycle skeleton structures, aliphatic amines-based ligands, and special metal-based complexes are summarized here. We also discuss their therapeutic targets and the risks that should be paid attention to in the future studies, aiming to provide information for researchers on metal-based complexes as antimicrobial agents and inspire the design and synthesis of new antimicrobial drugs.

Ultrasound-Stimulated Microbubbles Inhibit Aggressive Phenotypes and Promotes Radiosensitivity of esophageal squamous cell carcinoma

Ultrasound (US) is reported to improve the delivery efficiency of drugs loading onto large nanoparticles due to the sonoporation effect. Microbubbles (MBs) can be used as contrast agents of US expanding and contracting under low-amplitude US pressure waves. Ultrasound-stimulated microbubbles (USMBs) therapy is a promising option for the treatment of various cancers as a radiosensitizer. However, its role in esophageal squamous cell carcinoma (ESCC) remains unknown. In our study, human ESCC cell lines (KYSE-410, KYSE-1140) were treated with radiation solely, US alone, or radiation in combination with US or USMBs. The migration and invasion abilities of ESCC cells were examined by wound healing and Transwell assays. ESCC cell apoptosis was assessed using flow cytometry analysis and TUNEL assays. The levels of proteins associated with cell apoptosis and angiogenesis were measured by western blot analysis. A tube formation assay was performed to detect the ESCC cell angiogenesis. We found that USMBs at high levels most effectively most efficiently enhanced the effect of radiation, and significant changes in the viability (48%-51%), proliferation (1%), migration (63%-71%), invasion (52%) and cell apoptosis (31%-50%) of ESCC cells were observed compared with the control group in vitro. The ESCC angiogenesis was inhibited by US or radiation treatment and further inhibited by a combination of radiation and US or USMBs. USMBs at high levels most effectively enhanced the inhibitory effect of radiotherapy on ESCC cell apoptosis. Overall, USMBs enhanced the radiosensitivity of esophageal squamous cell carcinoma cells.Graphical abstractUSMBs treatment enhanced the anti-tumor effect of radiation on ESCC cell proliferation, migration, invasion, angiogenesis and apoptosis in vitro.1USMBs enhance the radiation-induced inhibition on ESCC cell growth2USMBs promote the radiation effect on ESCC cell apoptosis3USMBs enhance radiation-caused suppression on ESCC cell migration and invasion4USMBs enhance the suppression of radiation on ESCC angiogenesis[Figure: see text].

Utilization of nanotechnology in targeted radionuclide cancer therapy: monotherapy, combined therapy and radiosensitization

The rapid progress of nanomedicine field has a great influence on the different tumor therapeutic trends. It achieves a potential targeting of the therapeutic agent to the tumor site with neglectable exposure of the normal tissue. In nuclear medicine, nanocarriers have been employed for targeted delivery of therapeutic radioisotopes to the malignant tissues. This systemic radiotherapy is employed to overcome the external radiation therapy drawbacks. This review overviews studies concerned with investigation of different nanoparticles as promising carriers for targeted radiotherapy. It discusses the employment of different nanovehicles for achievement of the synergistic effect of targeted radiotherapy with other tumor therapeutic modalities such as hyperthermia and photodynamic therapy. Radiosensitization utilizing different nanosensitizer loaded nanoparticles has also been discussed briefly as one of the nanomedicine approach in radiotherapy.

Bismuth-213 for Targeted Radionuclide Therapy: From Atom to Bedside

In contrast to external high energy photon or proton therapy, targeted radionuclide therapy (TRNT) is a systemic cancer treatment allowing targeted irradiation of a primary tumor and all its metastases, resulting in less collateral damage to normal tissues. The α-emitting radionuclide bismuth-213 (213Bi) has interesting properties and can be considered as a magic bullet for TRNT. The benefits and drawbacks of targeted alpha therapy with 213Bi are discussed in this review, covering the entire chain from radionuclide production to bedside. First, the radionuclide properties and production of 225Ac and its daughter 213Bi are discussed, followed by the fundamental chemical properties of bismuth. Next, an overview of available acyclic and macrocyclic bifunctional chelators for bismuth and general considerations for designing a 213Bi-radiopharmaceutical are provided. Finally, we provide an overview of preclinical and clinical studies involving 213Bi-radiopharmaceuticals, as well as the future perspectives of this promising cancer treatment option.