Enhanced Radiosensitization by Gold Nanoparticles with Acid-Triggered Aggregation in Cancer Radiotherapy

Nano-Assisted Radiotherapy Strategies: New Opportunities for Treatment of Non-Small Cell Lung Cancer

Lung cancer is the second most commonly diagnosed cancer and a leading cause of cancer-related death, with non-small cell lung cancer (NSCLC) being the most prevalent type. Over 70% of lung cancer patients require radiotherapy (RT), which operates through direct and indirect mechanisms to treat cancer. However, RT can damage healthy tissues and encounter radiological resistance, making it crucial to enhance its precision to optimize treatment outcomes, minimize side effects, and overcome radioresistance. Integrating nanotechnology into RT presents a promising method to increase its efficacy. This review explores various nano-assisted RT strategies aimed at achieving precision treatment. These include using nanomaterials as radiosensitizers, applying nanotechnology to modify the tumor microenvironment, and employing nano-based radioprotectors and radiation-treated cell products for indirect cancer RT. We also explore recent advancements in nano-assisted RT for NSCLC, such as biomimetic targeting that alters mesenchymal stromal cells, magnetic targeting strategies, and nanosensitization with high-atomic number nanomaterials. Finally, we address the existing challenges and future directions of precision RT using nanotechnology, highlighting its potential clinical applications.

In Situ Aggregated Nanomanganese Enhances Radiation-Induced Antitumor Immunity

Radiosensitizers play a pivotal role in enhancing radiotherapy (RT). One of the challenges in RT is the limited accumulation of nanoradiosensitizers and the difficulty in activating antitumor immunity. Herein, a smart strategy was used to achieve in situ aggregation of nanomanganese adjuvants (MnAuNP-C&B) to enhance RT-induced antitumor immunity. The aggregated MnAuNP-C&B system overcomes the shortcomings of small-sized nanoparticles that easily flow back into blood vessels and diffuse into surrounding tissues, and it also prolongs the retention time of nanomanganese within cancer cells and tumors. The MnAuNP-C&B system significantly enhances the radiosensitization effect in RT. Additionally, the pH-responsive disassembly of MnAuNP-C&B triggers the release of Mn2+, further promoting RT-induced activation of the STING pathway and eliciting robust antitumor immunity. Overall, our study presents a smart strategy wherein in situ aggregation of nanomanganese effectively inhibits tumor growth through radiosensitization and the activation of antitumor immunity.

Photosynthetic bacteria-based whole-cell inorganic-biohybrid system for multimodal enhanced tumor radiotherapy

The whole-cell inorganic-biohybrid systems show special functions and wide potential in biomedical application owing to the exceptional interactions between microbes and inorganic materials. However, the hybrid systems are still in stage of proof of concept. Here, we report a whole-cell inorganic-biohybrid system composed of Spirulina platensis and gold nanoclusters (SP-Au), which can enhance the cancer radiotherapy through multiple pathways, including cascade photocatalysis. Such systems can first produce oxygen under light irradiation, then convert some of the oxygen to superoxide anion (•O2-), and further oxidize the glutathione (GSH) in tumor cells. With the combination of hypoxic regulation, •O2- production, GSH oxidation, and the radiotherapy sensitization of gold nanoclusters, the final radiation is effectively enhanced, which show the best antitumor efficacy than other groups in both 4T1 and A549 tumor models. Moreover, in vivo distribution experiments show that the SP-Au can accumulate in the tumor and be rapidly metabolized through biodegradation, further indicating its application potential as a new multiway enhanced radiotherapy sensitizer.

Selenium-Doped Nanoheterojunctions for Highly Efficient Cancer Radiosensitization

Exploring efficient and low-toxicity radiosensitizers to break through the bottleneck of radiation tolerance, immunosuppression and poor prognosis remains one of the critical developmental challenges in radiotherapy. Nanoheterojunctions, due to their unique physicochemical properties, have demonstrated excellent radiosensitization effects in radiation energy deposition and in lifting tumor radiotherapy inhibition. Herein, they doped selenium (Se) into prussian blue (PB) to construct a nano-heterojunction (Se@PB), which could promote the increase of Fe2+/Fe3+ ratio and conversion of Se to a high valence state with Se introduction. The Fe2+-Se-Fe3+ electron transfer chain accelerates the rate of electron transfer on the surface of the nanoparticles, which in turn endows it with efficient X-ray energy transfer and electron transport capability, and enhances radiotherapy physical sensitivity. Furthermore, Se@PB induces glutathione (GSH) depletion and Fe2+ accumulation through pro-Fenton reaction, thereby disturbs the redox balance in tumor cells and enhances biochemical sensitivity of radiotherapy. As an excellent radiosensitizer, Se@PB effectively enhances X-ray induced mitochondrial dysfunction and DNA damage, thereby promotes cell apoptosis and synergistic cervical cancer radiotherapy. This study elucidates the radiosensitization mechanism of Se-doped nanoheterojunction from the perspective of the electron transfer chain and biochemistry reaction, which provides an efficient and low-toxic strategy in radiotherapy.

Stimuli-triggered Self-Assembly of Gold Nanoparticles: Recent Advances in Fabrication and Biomedical Applications

Gold nanoparticles have been widely used in engineering, material chemistry, and biomedical applications owing to their ease of synthesis and functionalization, localized surface plasmon resonance (LSPR), great chemical stability, excellent biocompatibility, tunable optical and electronic property. In recent years, the decoration and modification of gold nanoparticles with small molecules, ligands, surfactants, peptides, DNA/RNA, and proteins have been systematically studied. In this review, we summarize the recent approaches on stimuli-triggered self-assembly of gold nanoparticles and introduce the breakthrough of gold nanoparticles in disease diagnosis and treatment. Finally, we discuss the current challenge and future prospective of stimuli-responsive gold nanoparticles for biomedical applications.

A bubble-enhanced lanthanide-doped up/down-conversion platform with tumor microenvironment response for dual-modal photoacoustic and near-infrared-II fluorescence imaging

As an important tumor diagnosis strategy in precision medicine, multimodal imaging has been widely studied. However, the weak imaging signal with low spatial resolution and the constant signal of lack of specific activation severely limit its disease diagnosis. Herein, a bubble-enhanced lanthanide-based up/down-conversion platform with tumor microenvironment response for dual-mode imaging, LDNP@DMSN-Au@CaCO3 nanoparticles (named as LDAC NPs) were successfully developed. Combining the advantages of photoacoustic imaging (PAI) and the second near-infrared window (NIR-II) fluorescence imaging (FI), significantly improved the accuracy of diseases diagnosis. LDAC NPs with flower-like structure were synthesized through the encapsulation of uniform lanthanide-doped nanoparticles (NaYbF4:Ce,Er@NaYF4 named LDNPs) with dendritic mesoporous silica (DMSN). The gold nanoparticles (Au NPs) were then in situ grown on the surface of DMSN and the surface were finally coated with a layer of calcium carbonate (CaCO3). Under the excitation of the 980 nm laser, LDNPs showed strong emission of NIR-II at 1550 nm due to the doping of Ce and Er ions, showcasing excellent spatial resolution and deep tissue penetration characteristics, while the resulting visible light emission (540 nm) enables Au NPs to generate PAI signals with the aid of LDNPs via the fluorescence resonance energy transfer effect. In acidic tumoral environment, CaCO3 layer could produce CO2 microbubbles, and the PAI signals of LDAC NPs could be further enhanced with the generation of CO2 bubbles due to the bubble cavitation effect. Simultaneously, the NIR-II FI of LDAC NPs was self-enhanced with the degradation of the CaCO3. This intelligent nanoparticle with stimulus-activated dual-mode imaging capability holds great promise in future precision diagnostics.

Engineered platelet cell motors for boosted cancer radiosensitization

Design of engineered cells to target and deliver nanodrugs to the hard-to-reach regions has become an exciting research area. However, the limited penetration and retention of cell-based carriers in tumor tissue restricted their therapeutic efficiency. Inspired by the enhanced delivery behavior of mobile micro/nanomotors, herein, urease-powered platelet cell motors (PLT@Au@Urease) capable of active locomotion, tumor targeting, and radiosensitizers delivery were designed for boosting radiosensitization. The engineered platelet cell motors were constructed by in situ synthesis and loading of radiosensitizers gold nanoparticles in platelets, and then conjugation with urease as the engine. Under physiological concentration of urea, thrust around PLT@Au@Urease motors can be generated via the biocatalytic reactions of urease, leading to rapid tumor cell targeting and enhanced cellular uptake of radiosensitizers. Encouragingly, in comparison with engineered PLT without propulsion capability (PLT@Au), the self-propelled PLT@Au@Urease motors could significantly increase intracellular ROS level and exacerbate nuclear DNA damage induced by γ-radiation, resulting in a remarkably high sensitization enhancement rate (1.89) than that of PLT@Au (1.08). In vivo experiments with 4 T1-bearing mice demonstrated that PLT@Au@Urease in combination with radiation therapy possessed good antitumor performance. Such an intelligent cell motor would provide a promising approach to enhance radiosensitization and broaden the applications of cell motor-based delivery systems.

Stimuli-Responsive Nanoradiosensitizers for Enhanced Cancer Radiotherapy

Radiotherapy (RT) has been a classical therapeutic method of cancer for several decades. It attracts tremendous attention for the precise and efficient treatment of local tumors with stimuli-responsive nanomaterials, which enhance RT. However, there are few systematic reviews summarizing the newly emerging stimuli-responsive mechanisms and strategies used for tumor radio-sensitization. Hence, this review provides a comprehensive overview of recently reported studies on stimuli-responsive nanomaterials for radio-sensitization. It includes four different approaches for sensitized RT, namely endogenous response, exogenous response, dual stimuli-response, and multi stimuli-response. Endogenous response involves various stimuli such as pH, hypoxia, GSH, and reactive oxygen species (ROS), and enzymes. On the other hand, exogenous response encompasses X-ray, light, and ultrasound. Dual stimuli-response combines pH/enzyme, pH/ultrasound, and ROS/light. Lastly, multi stimuli-response involves the combination of pH/ROS/GSH and X-ray/ROS/GSH. By elaborating on these responsive mechanisms and applying them to clinical RT diagnosis and treatment, these methods can enhance radiosensitive efficiency and minimize damage to surrounding normal tissues. Finally, this review discusses the additional challenges and perspectives related to stimuli-responsive nanomaterials for tumor radio-sensitization.

Peptide-containing nanoformulations: Skin barrier penetration and activity contribution

Transdermal drug delivery presents a less invasive pathway, circumventing the need to pass through the gastrointestinal tract and liver, thereby reducing drug breakdown, initial metabolism, and gastrointestinal discomfort. Nevertheless, the unique composition and dense structure of the stratum corneum present a significant barrier to transdermal delivery. This article presents an overview of the current developments in peptides and nanotechnology to address this challenge. Initially, we sum up peptide-containing nanoformulations for transdermal drug delivery, examining them through the lenses of both inorganic and organic materials. Particular emphasis is placed on the diverse roles that peptides play within these nanoformulations, including conferring functionality upon nanocarriers and enhancing the biological efficacy of drugs. Subsequently, we summarize innovative strategies for enhancing skin penetration, categorizing them into passive and active approaches. Lastly, we discuss the therapeutic potential of peptide-containing nanoformulations in addressing a range of diseases, drawing insights from the biological activities and functions of peptides. Furthermore, the challenges hindering clinical translation are also discussed, providing valuable insights for future advancements in transdermal drug delivery.

Reactive oxygen nanobiocatalysts: activity-mechanism disclosures, catalytic center evolutions, and changing states

Benefiting from low costs, structural diversities, tunable catalytic activities, feasible modifications, and high stability compared to the natural enzymes, reactive oxygen nanobiocatalysts (RONBCs) have become dominant materials in catalyzing and mediating reactive oxygen species (ROS) for diverse biomedical and biological applications. Decoding the catalytic mechanism and structure-reactivity relationship of RONBCs is critical to guide their future developments. Here, this timely review comprehensively summarizes the recent breakthroughs and future trends in creating and decoding RONBCs. First, the fundamental classification, activity, detection method, and reaction mechanism for biocatalytic ROS generation and elimination have been systematically disclosed. Then, the merits, modulation strategies, structure evolutions, and state-of-art characterisation techniques for designing RONBCs have been briefly outlined. Thereafter, we thoroughly discuss different RONBCs based on the reported major material species, including metal compounds, carbon nanostructures, and organic networks. In particular, we offer particular insights into the coordination microenvironments, bond interactions, reaction pathways, and performance comparisons to disclose the structure-reactivity relationships and mechanisms. In the end, the future challenge and perspectives for RONBCs are also carefully summarised. We envision that this review will provide a comprehensive understanding and guidance for designing ROS-catalytic materials and stimulate the wide utilisation of RONBCs in diverse biomedical and biological applications.

Gold-Enhanced Brachytherapy by a Nanoparticle-Releasing Hydrogel and 3D-Printed Subcutaneous Radioactive Implant Approach

Brachytherapy (BT) is a widely used clinical procedure for localized cervical cancer treatment. In addition, gold nanoparticles (AuNPs) have been demonstrated as powerful radiosensitizers in BT procedures. Prior to irradiation by a BT device, their delivery to tumors can enhance the radiation effect by generating low-energy photons and electrons, leading to reactive oxygen species (ROS) production, lethal to cells. No efficient delivery system has been proposed until now for AuNP topical delivery to localized cervical cancer in the context of BT. This article reports an original approach developed to accelerate the preclinical studies of AuNP-enhanced BT procedures. First, an AuNP-containing hydrogel (Pluronic F127, alginate) is developed and tested in mice for degradation, AuNP release, and biocompatibility. Then, custom-made 3D-printed radioactive BT inserts covered with a AuNP-containing hydrogel cushion are designed and administered by surgery in mice (HeLa xenografts), which allows for measuring AuNP penetration in tumors (≈100 µm), co-registered with the presence of ROS produced through the interactions of radiation and AuNPs. Biocompatible AuNPs-releasing hydrogels could be used in the treatment of cervical cancer prior to BT, with impact on  the total amount of radiation needed per BT treatment, which will result in benefits to the preservation of healthy tissues surrounding cancer.

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.

Reprogramming of the tumor microenvironment using a PCN-224@IrNCs/D-Arg nanoplatform for the synergistic PDT, NO, and radiosensitization therapy of breast cancer and improving anti-tumor immunity

The low X-ray attenuation coefficient of tumor soft tissue and the hypoxic tumor microenvironment (TME) during radiation therapy (RT) of breast cancer result in RT resistance and thus reduced therapeutic efficacy. In addition, immunosuppression induced by the TME severely limits the antitumor immunity of radiation therapy. In this paper, we propose a PCN-224@IrNCs/D-Arg nanoplatform for the synergistic radiosensitization, photodynamic, and NO therapy of breast cancer that also boosts antitumor immunity (PCN = porous coordination network, IrNCs = iridium nanocrystals, D-Arg = D-arginine). The local tumors can be selectively ablated via reprogramming the tumor microenvironment (TME), photodynamic therapy (PDT) and NO therapy, and the presence of the high-Z element Ir that sensitizes radiotherapy. The synergistic execution of these treatment modalities also resulted in adapted antitumor immune response. The intrinsic immunomodulatory effects of the nanoplatform also repolarize macrophages toward the M1 phenotype and induce dendritic cell maturation, activating antitumor T cells to induce immunogenic cell death as demonstrated in vitro and in vivo. The nanocomposite design reported herein represents a new regimen for the treatment of breast cancer through TME reprogramming to exert a synergistic effect for effective cancer therapy and antitumor immunity.

Illuminating and Radiosensitizing Tumors with 2DG-Bound Gold-Based Nanomedicine for Targeted CT Imaging and Therapy

Although radiotherapy is one of the most important curative treatments for cancer, its clinical application is associated with undesired therapeutic effects on normal or healthy tissues. The use of targeted agents that can simultaneously achieve therapeutic and imaging functions could constitute a potential solution. Herein, we developed 2-deoxy-d-glucose (2DG)-labeled poly(ethylene glycol) (PEG) gold nanodots (2DG-PEG-AuD) as a tumor-targeted computed tomography (CT) contrast agent and radiosensitizer. The key advantages of the design are its biocompatibility and targeted AuD with excellent sensitivity in tumor detection via avid glucose metabolism. As a consequence, CT imaging with enhanced sensitivity and remarkable radiotherapeutic efficacy could be attained. Our synthesized AuD displayed linear enhancement of CT contrast as a function of its concentration. In addition, 2DG-PEG-AuD successfully demonstrated significant augmentation of CT contrast in both in vitro cell studies and in vivo tumor-bearing mouse models. In tumor-bearing mice, 2DG-PEG-AuD showed excellent radiosensitizing functions after intravenous injection. Results from this work indicate that 2DG-PEG-AuD could greatly potentiate theranostic capabilities by providing high-resolution anatomical and functional images in a single CT scan and therapeutic capability.

Hypoxia-Responsive Aggregation of Gold Nanoparticles for Near-Infrared-II Photoacoustic Imaging-Guided Enhanced Radiotherapy

By directly harming cancer cells, radiotherapy (RT) is a crucial therapeutic approach for the treatment of cancers. However, the efficacy of RT is reduced by the limited accumulation and short retention time of the radiosensitizer in the tumor. Herein, we developed hypoxia-triggered in situ aggregation of nanogapped gold nanospheres (AuNNP@PAA/NIC NPs) within the tumor, resulting in second near-infrared window (NIR-II) photoacoustic (PA) imaging and enhanced radiosensitization. AuNNP@PAA/NIC NPs demonstrated increased accumulation and retention in hypoxic tumors, mainly due to the hypoxia-triggered aggregation. After aggregation of AuNNP@PAA/NIC NPs, the absorption of the system extended from visible light to NIR-II light owing to the plasmon coupling effects between adjacent nanoparticles. Compared to the normoxic tumor, the PA intensity at 1200 nm in the hypoxic tumor increased from 0.42 to 1.88 at 24 h postintravenous injection of AuNNP@PAA/NIC NPs, leading to an increase of 4.5 times. This indicated that the hypoxic microenvironment in the tumor successfully triggered the in situ aggregation of AuNNP@PAA/NIC NPs. The in vivo radiotherapeutic effect demonstrated that this hypoxia-triggered in situ aggregation of radiosensitizers significantly enhanced radiosensitization and thus resulted in superior cancer radiotherapeutic outcomes.

The Role of Functionalization and Size of Gold Nanoparticles in the Response of MCF-7 Breast Cancer Cells to Ionizing Radiation Comparing 2D and 3D In Vitro Models

Gold nanoparticles (AuNPs), as an agent enhancing radiosensitivity, play a key role in the potential treatment of breast cancer (BC). Assessing and understanding the kinetics of modern drug delivery systems is a crucial element that allows the implementation of AuNPs in clinical treatment. The main objective of the study was to assess the role of the properties of gold nanoparticles in the response of BC cells to ionizing radiation by comparing 2D and 3D models. In this research, four kinds of AuNPs, different in size and PEG length, were used to sensitize cells to ionizing radiation. The in vitro viability, uptake, and reactive oxygen species generation in cells were investigated in a time- and concentration-dependent manner using 2D and 3D models. Next, after the previous incubation with AuNPs, cells were irradiated with 2 Gy. The assessment of the radiation effect in combination with AuNPs was analyzed using the clonogenic assay and γH2AX level. The study highlights the role of the PEG chain in the efficiency of AuNPs in the process of sensitizing cells to ionizing radiation. The results obtained imply that AuNPs are a promising solution for combined treatment with radiotherapy.

Emerging plasmonic nanoparticles and their assemblies for cancer radiotherapy

Plasmonic nanoparticles and their assemblies have been widely used in biosensing, optical imaging, and biomedicine over the past few decades. Especially in the field of radiotherapy, the physicochemical properties of high-Z plasmonic nanomaterials endow them with the ability to sensitize radiotherapy. Compared with single particles, the assembled structure with tunable properties leads to versatile applications in drug delivery and cancer treatment. In this review, we focus on plasmonic nanoparticles and their assemblies for cancer radiotherapy. First, the sensitization mechanism of plasmonic radiosensitizers is briefly introduced. Subsequently, the recent progress in cancer radiotherapy is systematically discussed according to the structure and shape classification. Finally, the current challenges and future perspectives in this field are also discussed in detail.

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.

The Synergistic Effect of Cold Atmospheric Plasma Mediated Gold Nanoparticles Conjugated with Indocyanine Green as An Innovative Approach to Cooperation with Radiotherapy

OBJECTIVE

The multimodality treatment of cancer provides a secure and effective approach to improve the outcome of treatments. Cold atmospheric plasma (CAP) has got attention because of selectively target and kills cancer cells. Likewise, gold nanoparticles (GNP) have been introduced as a radiosensitizer and drug delivery with high efficacy and low toxicity in cancer treatment. Conjugating GNP with indocyanine green (ICG) can develop a multifunctional drug to enhance radio and photosensitivity. The purpose of this study is to evaluate the anticancer effects of GNP@ICG in radiotherapy (RT) and CAP on DFW melanoma cancer and HFF fibroblast normal cell lines.

MATERIALS AND METHODS

In this experimental study, the cells were irradiated to RT and CAP, alone and in combination with or without GNP@ICG at various time sequences between RT and CAP. Apoptosis Annexin V/PI, MTT, and colony formation assays evaluated the therapeutic effect. Finally, the index of synergism was calculated to compare the results.

RESULTS

Most crucially, the cell viability assay showed that RT was less toxic to tumors and normal cells, but CAP showed a significant anti-tumor effect on melanoma cells with selective toxicity. In addition, cold plasma sensitized melanoma cells to radiotherapy so increasing treatment efficiency. This effect is enhanced with GNP@ICG. In comparison to RT alone, the data showed that combination treatment greatly decreased monolayer cell colonization and boosted apoptotic induction.

CONCLUSION

The results provide new insights into the development of better approaches in radiotherapy of melanoma cells assisted plasma and nanomedicine.

Design strategies and applications of smart optical probes in the second near-infrared window

Over the last decade, a series of synergistic advances in the synthesis chemistries and imaging instruments have largely boosted a significant revolution, in which large-scale biomedical applications are now benefiting from optical bioimaging in the second near-infrared window (NIR-II, 1000-1700 nm). The large tissue penetration and limited autofluorescence associated with long-wavelength imaging improve translational potential of NIR-II imaging over common visible-light (400-650 nm) and NIR-I (750-900 nm) imaging, with ongoing profound effects on the studies of precision medicine. Unfortunately, the majority of NIR-II probes are designed as "always-on" luminescent imaging contrasts, continuously generating unspecific signals regardless of whether they reach pathological locations. Thus, in vivo imaging by traditional NIR-II probes usually suffers from weak detect precision due to high background noise. In this context, the advances of optical imaging now enter into an era of precise control of NIR-II photophysical kinetics. Developing NIR-II optical probes that can efficiently activate their luminescent signal in response to biological targets of interest and substantially suppress the background interferences have become a highly prospective research frontier. In this review, the merits and demerits of optical imaging probes from visible-light, NIR-I to NIR-II windows are carefully discussed along with the lens of stimuli-responsive photophysical kinetics. We then highlight the latest development in engineering methods for designing smart NIR-II optical probes. Finally, to appreciate such advances, challenges and prospect in rapidly growing study of smart NIR-II probes are addressed in this review.

Albumin-Modified Gold Nanoparticles as Novel Radiosensitizers for Enhancing Lung Cancer Radiotherapy

Background

Considering the strong attenuation of photons and the potential to increase the deposition of radiation, high-atomic number nanomaterials are often used as radiosensitizers in cancer radiotherapy, of which gold nanoparticles (GNPs) are widely used.

Materials and Methods

We prepared albumin-modified GNPs (Alb-GNPs) and observed their radiosensitizing effects and biotoxicity in human non-small-cell lung carcinoma tumor-bearing mice models.

Results

The prepared nanoparticles (Alb-GNPs) demonstrated excellent colloidal stability and biocompatibility at the mean size of 205.06 ± 1.03 nm. Furthermore, clone formation experiments revealed that Alb-GNPs exerted excellent radiosensitization, with a sensitization enhancement ratio (SER) of 1.432, which is higher than X-ray alone. Our in vitro and in vivo data suggested that Alb-GNPs enabled favorable accumulation in tumors, and the combination of Alb-GNPs and radiotherapy exhibited a relatively greater radiosensitizing effect and anti-tumor activity. In addition, no toxicity or abnormal irritating response resulted from the application of Alb-GNPs.

Conclusion

Alb-GNPs can be used as an effective radiosensitizer to improve the efficacy of radiotherapy with minimal damage to healthy tissues.

Advanced diagnostic and therapeutic strategies in nanotechnology for lung cancer

As a highly invasive thoracic malignancy with increasing prevalence, lung cancer is also the most lethal cancer worldwide due to the failure of effective early detection and the limitations of conventional therapeutic strategies for advanced-stage patients. Over the past few decades, nanotechnology has emerged as an important technique to obtain desired features by modifying and manipulating different objects on a molecular level and gained a lot of attention in many fields of medical applications. Studies have shown that in lung cancer, nanotechnology may be more effective and specific than traditional methods for detecting extracellular cancer biomarkers and cancer cells in vitro, as well as imaging cancer in vivo; Nanoscale drug delivery systems have developed rapidly to overcome various forms of multi-drug resistance and reduce detrimental side effects to normal tissues by targeting cancerous tissue precisely. There is no doubt that nanotechnology has the potential to enhance healthcare systems by simplifying and improving cancer diagnostics and treatment. Throughout this review, we summarize and highlight recent developments in nanotechnology applications for lung cancer in diagnosis and therapy. Moreover, the prospects and challenges in the translation of nanotechnology-based diagnostic and therapeutic methods into clinical applications are also discussed.

Glioma diagnosis and therapy: Current challenges and nanomaterial-based solutions

Glioma is often referred to as one of the most dreadful central nervous system (CNS)-specific tumors with rapidly-proliferating cancerous glial cells, accounting for nearly half of the brain tumors at an annual incidence rate of 30-80 per a million population. Although glioma treatment remains a significant challenge for researchers and clinicians, the rapid development of nanomedicine provides tremendous opportunities for long-term glioma therapy. However, several obstacles impede the development of novel therapeutics, such as the very tight blood-brain barrier (BBB), undesirable hypoxia, and complex tumor microenvironment (TME). Several efforts have been dedicated to exploring various nanoformulations for improving BBB permeation and precise tumor ablation to address these challenges. Initially, this article briefly introduces glioma classification and various pathogenic factors. Further, currently available therapeutic approaches are illustrated in detail, including traditional chemotherapy, radiotherapy, and surgical practices. Then, different innovative treatment strategies, such as tumor-treating fields, gene therapy, immunotherapy, and phototherapy, are emphasized. In conclusion, we summarize the article with interesting perspectives, providing suggestions for future glioma diagnosis and therapy improvement.

An overview of the intracellular localization of high-Z nanoradiosensitizers

Radiation therapy (RT) is a method commonly used for cancer treatment worldwide. Commonly, RT utilizes two routes for combating cancers: 1) high-energy radiation to generate toxic reactive oxygen species (ROS) (through the dissociation of water molecules) for damaging the deoxyribonucleic acid (DNA) inside the nucleus 2) direct degradation of the DNA. However, cancer cells have mechanisms to survive under intense RT, which can considerably decrease its therapeutic efficacy. Excessive radiation energy damages healthy tissues, and hence, low doses are applied for cancer treatment. Additionally, different radiosensitizers were used to sensitize cancer cells towards RT through individual mechanisms. Following this route, nanoparticle-based radiosensitizers (herein called nanoradiosensitizers) have recently gained attention owing to their ability to produce massive electrons which leads to the production of a huge amount of ROS. The success of the nanoradiosensitizer effect is closely correlated to its interaction with cells and its localization within the cells. In other words, tumor treatment is affected from the chain of events which is started from cell-nanoparticle interaction followed by the nanoparticles direction and homing inside the cell. Therefore, passive or active targeting of the nanoradiosensitizers in the subcellular level and the cell-nano interaction would determine the efficacy of the radiation therapy. The importance of the nanoradiosensitizer's targeting is increased while the organelles beyond nucleus are recently recognized as the mediators of the cancer cell death or resistance under RT. In this review, the principals of cell-nanomaterial interactions and which dominate nanoradiosensitizer efficiency in cancer therapy, are thoroughly discussed.

Stepwise-Enhanced Tumor Targeting of Near-Infrared Emissive Au Nanoclusters with High Quantum Yields and Long-Term Stability

We developed an in situ coordination-driven spatially confined strategy for preparing near-infrared emissive gold nanoclusters encapsulated by fluorinated polymers (AuNCs@PF, λ_max = 810 nm) with good stability and high quantum yields (27.7%), far higher than those previously reported for NIR AuNCs (>800 nm). Based on the stepwise enhancements including long blood circulation-induced passive tumor targeting, fluoro-enhanced tumor permeation, and tumor microenvironment (weak acid)-induced aggregation retention in cells, these AuNCs demonstrated bright and stable NIR fluorescence imaging ability in tumors. Additionally, the AuNCs@PF were capable of fluorine magnetic resonance imaging and computed tomographic imaging. The multimodal imaging of tumor-bearing mice clearly implied the potential of AuNCs@PF in biomedical fields.

In-Situ Assembly of Janus Nanoprobe for Cancer Activated NIR-II Photoacoustic Imaging and Enhanced Photodynamic Therapy

Inorganic nanoprobes have attracted increasing attention in the biomedical field due to their versatile functionalities and excellent optical properties. However, conventional nanoprobes have a relatively low retention time in the tumor and are mostly applied in the first near-infrared window (NIR-I, 650-950 nm), limiting their applications in accurate and deep tissue imaging. Herein, we develop a Janus nanoprobe, which can undergo tumor microenvironment (TME)-induced aggregation, hence, promoting tumor retention time and providing photoacoustic (PA) imaging in the second NIR (NIR-II, 950-1700 nm) window, and enhancing photodynamic therapy (PDT) effect. Ternary Janus nanoprobe is composed of gold nanorod (AuNR) coated with manganese dioxide (MnO₂) and photosensitizer pyropheophorbide-a (Ppa) on two ends of AuNR, respectively, named as MnO₂-AuNR-Ppa. In the tumor, MnO₂ could be etched by glutathione (GSH) to release Mn²⁺, which is coordinated with multiple Ppa molecules to induce in situ aggregation of AuNRs. The aggregation of AuNR effectively improves the NIR-II photoacoustic signal in vivo. Moreover, the increased retention time of nanoprobes and GSH reduction in the tumor greatly improve the PDT effect. We believe that this work will inspire further research on specific in situ aggregation of inorganic nanoparticles.

Next-generation engineered nanogold for multimodal cancer therapy and imaging: a clinical perspectives

Cancer is one of the significant threats to human life. Although various latest technologies are currently available to treat cancer, it still accounts for millions of death each year worldwide. Thus, creating a need for more developed and novel technologies to combat this deadly condition. Nanoparticles-based cancer therapeutics have offered a promising approach to treat cancer effectively while minimizing adverse events. Among various nanoparticles, nanogold (AuNPs) are biocompatible and have proved their efficiency in treating cancer because they can reach tumors via enhanced permeability and retention effect. The size and shape of the AuNPs are responsible for their diverse therapeutic behavior. Thus, to modulate their therapeutic values, the AuNPs can be synthesized in various shapes, such as spheres, cages, flowers, shells, prisms, rods, clusters, etc. Also, attaching AuNPs with single or multiple targeting agents can facilitate the active targeting of AuNPs to the tumor tissue. The AuNPs have been much explored for photothermal therapy (PTT) to treat cancer. In addition to PTT, AuNPs-based nanoplatforms have been investigated for combinational multimodal therapies in the last few years, including photodynamic therapy, chemotherapy, radiotherapy, immunotherapy, etc., to ablate cancer cells. Thus, the present review focuses on the recent advancements in the functionalization of AuNPs-based nanoconstructs for cancer imaging and therapy using combinatorial multimodal approaches to treat various cancers.

Enzyme-mediated intratumoral self-assembly of nanotheranostics for enhanced imaging and tumor therapy

Enzyme-mediated intratumoral self-assembled (EMISA) nanotheranostics represent a new class of smart agents for combined imaging and therapy of cancer. Cancer cells overexpress various enzymes that are essential for high metabolism, fast proliferation, and tissue invasion and metastasis. By conjugating small molecules that contain an enzyme-specific cleavage site to appropriate chemical linkers, it is possible to induce self-assembly of nanostructures in tumor cells having the target enzyme. This approach of injecting small theranostic molecules that eventually become larger nanotheranostics in situ avoids some of the major limitations that are encountered when injecting larger, pre-assembled nanotheranostics. The advantage of EMISA nanotheranostics include the avoidance of nonspecific uptake and rapid clearance by phagocytic cells, increased cellular accumulation, reduced drug efflux and prolonged cellular exposure time, all of which lead to an amplified imaging signal and therapeutic efficacy. We review here the different approaches that can be used for preparing EMISA-based organic, inorganic, or organic/inorganic hybrid nanotheranostics based on noncovalent interactions and/or covalent bonding. Imaging examples are shown for fluorescence imaging, nuclear imaging, photoacoustic imaging, Raman imaging, computed tomography imaging, bioluminescent imaging, and magnetic resonance imaging. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Biology-Inspired Nanomaterials > Peptide-Based Structures.

Nanoswimmers Based on Capped Janus Nanospheres

Nanoswimmers are synthetic nanoscale objects that convert the available surrounding free energy to a directed motion. For example, bacteria with various flagella types serve as textbook examples of the minuscule swimmers found in nature. Along these lines, a plethora of artificial hybrid and non-hybrid nanoswimmers have been introduced, and they could find many uses, e.g., for targeted drug delivery systems (TDDSs) and controlled drug treatments. Here, we discuss a certain class of nanoparticles, i.e., functional, capped Janus nanospheres that can be employed as nanoswimmers, their subclasses and properties, as well as their various implementations. A brief outlook is given on different fabrication and synthesis methods, as well as on the diverse compositions used to prepare nanoswimmers, with a focus on the particle types and materials suitable for biomedical applications. Several recent studies have shown remarkable success in achieving temporally and spatially controlled drug delivery in vitro using Janus-particle-based TDDSs. We believe that this review will serve as a concise introductory synopsis for the interested readers. Therefore, we hope that it will deepen the general understanding of nanoparticle behavior in biological matrices.

Dose Rate Effects on the Selective Radiosensitization of Prostate Cells by GRPR-Targeted Gold Nanoparticles

For a while, gold nanoparticles (AuNPs) have been recognized as potential radiosensitizers in cancer radiation therapy, mainly due to their physical properties, making them appealing for medical applications. Nevertheless, the performance of AuNPs as radiosensitizers still raises important questions that need further investigation. Searching for selective prostate (PCa) radiosensitizing agents, we studied the radiosensitization capability of the target-specific AuNP-BBN in cancer versus non-cancerous prostate cells, including the evaluation of dose rate effects in comparison with non-targeted counterparts (AuNP-TDOTA). PCa cells were found to exhibit increased AuNP uptake when compared to non-tumoral ones, leading to a significant loss of cellular proliferation ability and complex DNA damage, evidenced by the occurrence of multiple micronucleus per binucleated cell, in the case of PC3 cells irradiated with 2 Gy of γ-rays, after incubation with AuNP-BBN. Remarkably, the treatment of the PC3 cells with AuNP-BBN led to a much stronger influence of the dose rate on the cellular survival upon γ-photon irradiation, as well as on their genomic instability. Overall, AuNP-BBN emerged in this study as a very promising nanotool for the efficient and selective radiosensitization of human prostate cancer PC3 cells, therefore deserving further preclinical evaluation in adequate animal models for prostate cancer radiotherapy.

Degradable Tumor-Responsive Iron-Doped Phosphate-Based Glass Nanozyme for H2O2 Self-Supplying Cancer Therapy

Tumor microenvironment (TME)-responsive chemodynamic therapy (CDT) mediated by nanozymes has been extensively studied both experimentally and theoretically, but the low catalytic efficiency due to insufficient H₂O₂ in the TME and the poor biodegradability of the nanozymes are still main challenges for clinical translation of nanozymes. Herein, we designed a H₂O₂ self-supplying nanozyme bearing glucose oxidase (GOX) and polyethyleneimine based on a degradable iron-doped phosphate-based glass (FePBG) nanomimic (FePBG@GOX), which can convert endogenous glucose into toxic hydroxyl radicals. The GOX loaded on the nanozyme can effectively consume glucose in tumor cells to produce a large amount of H₂O₂ to make up for the lack of H₂O₂ in the TME. Thereafter, enormous hydroxyl radicals, based on a Fenton reaction of FePBG without any exogenous H₂O₂, are generated to induce severe apoptosis of tumor cells. The nanozyme exhibits enhanced in vitro cytotoxicity in a high-glucose medium than in a low-glucose medium, illustrating sufficient generation of H₂O₂ by GOX. The excellent in vivo antitumor efficacy is manifested by a high tumor growth inhibition ratio of 94.65% in model mice. Excellent intrinsic biodegradability owing to its phosphate-based glass nature is a remarkable advantage of the prepared FePBG nanozyme over most other reported nanozymes. Big concerns about side effects caused by long-time residence in living organisms are eliminated since it degrades not only in an acid medium but also in a neutral physiological environment. Therefore, this novel strategy of the TME-responsive H₂O₂ self-supplying nanozyme based on an endogenous cascade catalytic reaction opens up an avenue for designing degradable nanozymes in CDT.

When imaging meets size-transformable nanosystems

Imaging techniques, including magnetic, optical, acoustic and nuclear imaging, are gaining popularity as a research tool and clinical diagnostics. The advent of imaging agents-incorporated nanosystems (NSs), with sufficient contrast and high resolution, facilitates better monitoring of disease progression, targeted delivery and therapeutic process. Of note, the size of NSs remarkably affects imaging performance, while both large and small NSs enjoy respective features and superiority for imaging aspect, including penetration depth, signal-to-background ratio and spatiotemporal resolution. In this review, after a systematic summary of the basic knowledge of imaging techniques and its relation with size-tunable strategies, we further provide insights into the opportunities and challenges facing size-transformable NSs of the future for bio-imaging application and clinical translation.

Photothermal conversion performance and acid-induced aggregation of PLNP-Bi2S3 composite nanoplatforms

Poly(sodium 4-styrenesulfonate) (PSS) molecule modified PLNP-Bi₂S₃ composite nanoplatforms were constructed by using polyvinylpyrrolidone (PVP) modified Bi₂S₃ nanoparticles (∼4.6 nm) as a photothermal agent and hexadecyl trimethyl ammonium bromide (CTAB) coated Zn₂Ga_2.98Ge_0.75O₈:Cr_0.02³⁺ (ZGGO:Cr³⁺@CTAB) persistent luminescence nanoparticles (PLNPs) through electrostatic adsorption. It is found that the above composite nanoplatforms have excellent laser-irradiation thermal stability and good photothermal conversion performance. The measured photothermal conversion efficiency is ∼44%, which is higher than that (∼37%) of the PLNP-GNR (gold nanorod) composite nanoplatforms. Meanwhile, PSS modified PLNP-Bi₂S₃ composite nanoplatforms exhibited good solution dispersibility in blood and normal tissue environments. While reaching tumor sites, the above composite nanoplatforms can be rapidly accumulated in cancer cells with acidic environments. This pH-responsive acid-induced aggregation can be ascribed to the chemical reaction induced by the protonation of PSS modified PLNP-Bi₂S₃ composite nanoplatforms with a negatively charged surface in the acidic environments. Our results suggest that PSS modified PLNP-Bi₂S₃ composite nanoplatforms might be applied to precision diagnosis and therapy of deep-tissue tumors.

A Universally EDTA-Assisted Synthesis of Polytypic Bismuth Telluride Nanoplates with a Size-Dependent Enhancement of Tumor Radiosensitivity and Metabolism In Vivo

Bismuth telluride (Bi₂Te₃) is an available thermoelectric material with the lowest band gap among bismuth chalcogenides, revealing a broad application in photocatalysis. Unfortunately, its size and morphology related to a radio-catalysis property have rarely been explored. Herein, an ethylenediaminetetraacetic acid (EDTA)-assisted hydrothermal strategy was introduced to synthesize polytypic Bi₂Te₃ nanoplates (BT NPs) that exhibit size-dependent radio-sensitization and metabolism characteristics in vivo. By simply varying the molar ratio of EDTA/Bi³⁺ during the reaction, BT NPs with different sizes and morphologies were obtained. EDTA acting as chelating agent and "capping" agent contributed to the homogeneous growth of BT NPs by eliminating dangling bonds and reducing the surface energy of different facets. Further analyzing the size-dependent radio-sensitization mechanism, larger-sized BT NPs generated holes that preferentially catalyzed the conversion of OH^- to ·OH when irradiated with X-rays, while the smaller-sized BT NPs exhibited faster decay kinetics producing higher ¹O₂ levels to enhance radiotherapy effects. A metabolomic analysis revealed that larger-sized BT NPs were oxidized into Bi(O_x) in the liver via a citrate cycle pathway, whereas smaller-sized BT NPs accumulated in the kidney and were excreted in urine in the form of ions by regulating the metabolism of glutamate. In a cervical cancer model, BT NPs combined with X-ray irradiation significantly antagonized tumor suppression through the promotion of apoptosis in tumor cells. Consequently, in addition to providing a prospect of BT NPs as an efficient radio-sensitizer to boost the tumor radiosensitivity, we put forth a strategy that can be universally applied in synthesizing metal chalcogenides for catalysis-promoted radiotherapy.

Biocompatible hypocrellin A-Fe(III) nanoparticles exhibiting efficient photo-activated CDT in vitro and in vivo

Chemodynamic therapy (CDT) is novel and promising for cancer treatment, however, the potential systematic toxicity of the used nanoparticles is still a big concern. In this work the biocompatible hypocrellin A-Fe(III) nanoparticles (HA-Fe(III) NPs) were synthesized and studied. The CDT effect of HA-Fe(III) NPs in the dark is negligible but can be photo-activated upon red light irradiation, which is meaningful to realize precise CDT treatment by selective light irradiation. Moreover, HA-Fe(III) NPs can also generate O₂˙^-, which may be converted into H₂O₂ to further enhance the CDT effect. As a result, HA-Fe(III) NPs had little cytotoxicity in the dark at the concentration up to 200 μg ml^-1, but exhibited efficient CDT activity upon red light irradiation under both normoxic and hypoxic conditions. The in vivo results also showed that HA-Fe(III) NPs can efficiently inhibit tumor growth upon 628 nm light irradiation.

Tumor microenvironment-responsive size-switchable drug delivery nanosystems

INTRODUCTION

Compared with ordinary chemotherapeutic drugs, the variable-size nanoparticles (NPs) have better therapeutic effects and fewer side effects.

AREAS COVERED

This review mainly summarizes the strategies used to construct smart, size-tunable nanocarriers based on characteristic factors of tumor microenvironment (TME) to dramatically increase the penetration and retention of drugs within tumors.

EXPERT OPINION

Nanosystems with changeable sizes based on the TME have been extensively studied in the past decade, and their permeability and retention have been greatly improved, making them a very promising treatment for tumors.

Supramolecular Radiosensitizer Based on Hypoxia-Responsive Macrocycle

Radiotherapy (RT) has been viewed as one of the most effective and extensively applied curatives in clinical cancer therapy. However, the radioresistance of tumor severely discounts the radiotherapy outcomes. Here, an innovative supramolecular radiotherapy strategy, based on the complexation of a hypoxia-responsive macrocycle with small-molecule radiosensitizer, is reported. To exemplify this tactic, a carboxylated azocalix[4]arene (CAC4A) is devised as molecular container to quantitatively package tumor sensitizer banoxantrone dihydrochloride (AQ4N) through reversible host-guest interaction. Benefited from the selective reduction of azo functional groups under hypoxic microenvironment, the supramolecular prodrug CAC4A•AQ4N exhibits high tumor accumulation and efficient cellular internalization, thereby significantly amplifying radiation-mediated tumor destruction without appreciable systemic toxicity. More importantly, this supramolecular radiotherapy strategy achieves an ultrahigh sensitizer enhancement ratio (SER) value of 2.349, which is the supreme among currently reported noncovalent-based radiosensitization approach. Further development by applying different radiosensitizing drugs can make this supramolecular strategy become a general platform for boosting therapeutic effect in cancer radiotherapies, tremendously promising for clinical translation.

Size-Transformable Bicomponent Peptide Nanoparticles for Deep Tumor Penetration and Photo-Chemo Combined Antitumor Therapy

The suitable size of multifunctional nanomedicines strongly influences their physicochemical properties and actions in biological systems, for example, prolonged blood circulation time, efficient tumor accumulation, and deep tumor penetration. However, it is still a great challenge to construct size-transformable nanoparticles (NPs) for both efficient accumulation and penetration throughout tumor tissue. Herein, a size-transformed multifunctional NP is developed through a simple bicomponent assembling strategy for enhanced tumor penetration and efficient photo-chemo combined antitumor therapy, due to the acidic tumor microenvironment and near infrared-laser irradiation induced size-shrink. This multifunctional bicomponent NP (PP NP) driven by electrostatic interaction is composed of negatively charged peptide amphiphile (PA1) and positively charged peptide prodrug (PA2). PP NPs (≈170 nm) have been proven to improve blood circulation time and stability in biological environments. Interestingly, PP NPs can reassemble small NPs (<30 nm) by responding to acidic tumor microenvironment and near-infrared laser irradiation, which facilitates deep tumor penetration and improves cellular internalization. By integrating fluorescence imaging, tumor targeting, deep tumor penetration, and combined photo-chemotherapy, PP NPs exhibit excellent in vivo antitumor efficacy. This study might provide an insight for developing a bicomponent assembling system with efficient tumor penetration and multimode for antitumor therapy.

Stapled Liposomes Enhance Cross-Priming of Radio-Immunotherapy

The release of tumor-associated antigens (TAAs) and their cross-presentation in dendritic cells (DCs) are crucial for radio-immunotherapy. However, the irradiation resistance of tumor cells usually results in limited TAA generation and release. Importantly, TAAs internalized by DCs are easily degraded in lysosomes, resulting in unsatisfactory extent of TAA cross-presentation. Herein, an antigen-capturing stapled liposome (ACSL) with a robust structure and bioactive surface is developed. The ACSLs capture and transport TAAs from lysosomes to the cytoplasm in DCs, thereby enhancing TAA cross-presentation. l-arginine encapsulated in ACSLs induces robust T cell-dependent antitumor response and immune memory in 4T1 tumor-bearing mice after local irradiation, resulting in significant tumor suppression and an abscopal effect. Replacing l-arginine with radiosensitizers, photosensitizers, and photothermal agents may make ACSL a universal platform for the rapid development of various combinations of anticancer therapies.

Advances in FePt-involved nano-system design and application for bioeffect and biosafety

The rapid development and wide application of nanomaterial-involved theranostic agents have drawn surging attention for improving the living standard of humankind and healthcare conditions. In this review, recent developments in the design, synthesis, biocompatibility evaluation and potential nanomedicine applications of FePt-involved nano-systems are summarized, especially for cancer theranostic and biological molecule detection. The in vivo multi-model imaging capability is discussed in detail, including magnetic resonance imaging and computed tomography. Furthermore, we highlight the significant achievements of various FePt-involved nanotherapeutics for cancer treatment, such as drug delivery, chemodynamic therapy, photodynamic therapy, radiotherapy and immunotherapy. In addition, a series of FePt-involved nanocomposites are also applied for biological molecule detection, such as H₂O₂, glucose and naked-eye detection of cancer cells. Ultimately, we also summarize the challenges and prospects of FePt-involved nano-systems in nanocatalytic medicine. This review is expected to give a general pattern for the development of FePt-involved nano-systems in the field of nanocatalytic medicine and analytical determination.

Monitoring Nitric Oxide-Induced Hypoxic Tumor Radiosensitization by Radiation-Activated Nanoagents under BOLD/DWI Imaging

Tumor heterogeneity leads to unpredictable radiotherapeutic outcomes although multiple sensitization strategies have been developed. Real-time monitoring of treatment response through noninvasive imaging methods is critical and a great challenge in optimizing radiotherapy. Herein, we propose a combined functional magnetic resonance imaging approach (blood-oxygen-level-dependent/diffusion-weighted (BOLD/DWI) imaging) for monitoring tumor response to nitric oxide (NO)-induced hypoxic radiosensitization achieved by radiation-activated nanoagents (NSC@SiO₂-SNO NPs). This nanoagent carrying NO donors can efficiently concentrate in tumors and specifically produce high concentrations of NO under radiation. In vitro and in vivo studies show that this nanoagent can effectively reduce tumor hypoxia, promote radiation-induced apoptosis and DNA damage under hypoxia, and ultimately inhibit tumor growth. In vivo BOLD/DWI imaging enables noninvasive monitoring of improvements in tumor oxygen levels and radiosensitivity during treatment with this nanostrategy by quantifying functional parameters. This work demonstrates that BOLD/DWI imaging is a useful tool for evaluating tumor response and monitoring the effectiveness of radiotherapeutic strategies aimed at improving hypoxia, with great clinical potential.

Multifunctional Hybrid Hydrogel Enhanced Antitumor Therapy through Multiple Destroying DNA Functions by a Triple-Combination Synergistic Therapy

Brachytherapy, as an effective setting for precise cancer therapy in clinic, can lead to serious DNA damage. However, its therapeutic efficacy is always limited by the DNA self-repair property, tumor hypoxia-associated radiation resistance as well as inhomogeneous distribution of the radioactive material. Herein, a multifunctional hybrid hydrogel (¹³¹ I-hydrogel/DOX/GNPs aggregates) is developed by loading gold nanoparticle aggregates (GNPs aggregates) and DOX into a radionuclide iodine-131 (¹³¹ I) labelled polymeric hydrogels (¹³¹ I-PEG-P(Tyr)₈ ) for tumor destruction by completely damaging DNA self-repair functions. This hybrid hydrogel exhibits excellent photothermal/radiolabel stability, biocompatibility, and fluorescence/photothermal /SPECT imaging properties. After local injection, the sustained releasing DOX within tumor greatly inhibits the DNA replication. Meanwhile, GNPs aggregates as a radiosensitizer and photosensitizer show a significant improvement of brachytherapeutic efficacy and cause serious DNA damage. Simultaneously, GNPs aggregates induce mild photothermal therapy under 808 nm laser irradiation, which not only inhibits self-repair of the damaged DNA but also effectively relieves tumor hypoxic condition to enhance the therapeutic effects of brachytherapy, leading to a triple-synergistic destruction of DNA functions. Therefore, this study provides a highly efficient tumor synergistic therapy platform and insight into the synergistic antitumor mechanism in DNA level.

Hafnium Oxide-Based Nanoplatform for Combined Chemoradiotherapy

Recently, the combined therapy has become one of the main approaches in cancer treatment. Combining different approaches may provide a significant outcome by triggering several death mechanisms or causing increased damage of tumor cells without hurting healthy ones. The supramolecular nanoplatform based on a high-Z metal reported here is a suitable system for the targeted delivery of chemotherapeutic compounds, imaging, and an enhanced radiotherapy outcome. HfO₂ nanoparticles coated with oleic acid and a monomethoxypoly(ethylene glycol)-poly(ε-caprolactone) copolymer shell (nanoplatform) are able to accumulate inside cancer cells and release doxorubicin (DOX) under specific conditions. Neither uncoated nor coated nanoparticles show any cytotoxicity in vitro. DOX loaded onto a nanoplatform demonstrates a lower IC₅₀ value than pure DOX. X-ray irradiation of cancer cells loaded with a nanoplatform shows a higher death rate than that for cells without nanoparticles. These results provide an important foundation for the development of complex nanoscale systems for combined cancer treatment.

Light-triggered nitric oxide release and structure transformation of peptide for enhanced intratumoral retention and sensitized photodynamic therapy

Tumor-targeted delivery of nanomedicine is of great importance to improve therapeutic efficacy of cancer and minimize systemic side effects. Unfortunately, nowadays the targeting efficiency of nanomedicine toward tumor is still quite limited and far from clinical requirements. In this work, we develop an innovative peptide-based nanoparticle to realize light-triggered nitric oxide (NO) release and structural transformation for enhanced intratumoral retention and simultaneously sensitizing photodynamic therapy (PDT). The designed nanoparticle is self-assembled from a chimeric peptide monomer, TPP-RRRKLVFFK-Ce6, which contains a photosensitive moiety (chlorin e6, Ce6), a β-sheet-forming peptide domain (Lys-Leu-Val-Phe-Phe, KLVFF), an oligoarginine domain (RRR) as NO donor and a triphenylphosphonium (TPP) moiety for targeting mitochondria. When irradiated by light, the constructed nanoparticles undergo rapid structural transformation from nanosphere to nanorod, enabling to achieve a significantly higher intratumoral accumulation by 3.26 times compared to that without light irradiation. More importantly, the conversion of generated NO and reactive oxygen species (ROS) in a light-responsive way to peroxynitrite anions (ONOO^-) with higher cytotoxicity enables NO to sensitize PDT in cancer treatment. Both in vitro and in vivo studies demonstrate that NO sensitized PDT based on the well-designed transformable nanoparticles enables to eradicate tumors efficiently. The light-triggered transformable nanoplatform developed in this work provides a new strategy for enhanced intratumoral retention and improved therapeutic outcome.

Aggregation of Gold Nanoparticles Triggered by Hydrogen Peroxide-Initiated Chemiluminescence for Activated Tumor Theranostics

Developing endogenous photo-activated theranostic platforms to overcome the limitation of low tissue-penetration from external light sources is highly significant for cancer diagnosis and treatment. We report a H₂ O₂ -initiated chemiluminescence (CL)-triggered nanoparticle aggregation strategy to activate theranostic functions of gold nanoparticles (AuNPs) for effective tumor imaging and therapy. Two types of AuNPs (tAuNP & mAuNP) were designed and fabricated by conjugating 2,5-diphenyltetrazole and methacrylic acid onto the surface of AuNPs, respectively. Luminol was adsorbed onto the mAuNPs to afford self-illuminating mAuNP/Lu NPs that could produce strong CL by reaction with H₂ O₂ in the tumor microenvironment, which triggers significant aggregation of AuNPs resulting in enhanced accumulation and retention of AuNPs for activated photoacoustic imaging and photothermal therapy of tumors. We thus believe that this approach may offer a promising tool for effective tumor treatment.

All-purpose nanostrategy based on dose deposition enhancement, cell cycle arrest, DNA damage, and ROS production as prostate cancer radiosensitizer for potential clinical translation

Radiotherapy (RT) is one of the main treatments for men with prostate cancer (PCa). To date, numerous sophisticated nano-formulations as radiosensitizers have been synthesized with inspiring therapeutic effects both in vitro and in vivo; however, almost all the attention has been paid on the enhanced dose deposition effect by secondary electrons of nanomaterials with high atomic numbers (Z); despite this, cell-cycle arrest, DNA damage, and also reactive oxygen species (ROS) production are critical working mechanisms that account for radiosensitization. Herein, an 'all-purpose' nanostrategy based on dose deposition enhancement, cell cycle arrest, and ROS production as prostate cancer radiosensitizer for potential clinical translation was proposed. The rather simple structure of docetaxel-loaded Au nanoparticles (NPs) with prostate specific membrane antigen (PSMA) ligand conjugation have been successfully synthesized. Enhanced cellular uptake achieved via the selective internalization of the NPs by PCa cells with positive PSMA expression could guarantee enhanced dose deposition. Moreover, the as-synthesized nanosystem could effectively arrest the cell cycle at G2/M phases, which would reduce the ability of DNA damage repair for more irradiation sensitive of the PCa cells. Moreover, the G2/M phase arrest would further promote cascade retention and the enrichment of NPs within the cells. Furthermore, ROS generation and double strand breaks greatly promoted by NPs under irradiation (IR) could also provide an underlying basis for effective radiosensitizers. In vitro and in vivo investigations confirmed the as-synthesized NPs as an effective nano-radiosensitizer with ideal safety. More importantly, all moieties within the present nanosystem have been approved by FDA for the purpose of PCa treatment, thus making it highly attractive for clinical translation.

A Honeycomb-Like Bismuth/Manganese Oxide Nanoparticle with Mutual Reinforcement of Internal and External Response for Triple-Negative Breast Cancer Targeted Therapy

Triple-negative breast cancer (TNBC) exhibits aggressive behavior and high levels of metastasis owing to its complex heterogeneous structure and lack of specific receptors. Here, tumor cell membrane (CM)-coated bismuth/manganese oxide nanoparticles (NPs) with high indocyanine green (ICG) payload up to 50.6 wt% (mBMNI NPs) for targeted TNBC therapy are constructed. The extra-high drug load Bi@Bi₂ O₃ @MnO_x NPs (honey-comb like structure) are formed by Kirkendall effect and electrostatic attraction. After modified with CM, they can home into tumor sites precisely, where they respond to internal overexpressed glutathione (GSH), releasing Mn²⁺ for chemodynamic therapy (CDT) with GSH depletion, while H₂ O₂ degrades into O₂ enabling relief of tumor hypoxia. In response to external near-infrared irradiation, mBMNI NPs intelligently generate vigorous heat and single oxygen (¹ O₂ ) for photothermal therapy (PTT) and photodynamic therapy (PDT) owing to high load. Importantly, O₂ production and GSH consumption during the internal response reinforce external PDT, while the heat generated through PTT during the external response promotes internal CDT. The honeycomb-like structure with high ICG load and mutual reinforcement between internal and external response results in excellent therapeutic effects against TNBC.