Codoping Enhanced Radioluminescence of Nanoscintillators for X-ray-Activated Synergistic Cancer Therapy and Prognosis Using Metabolomics

A Hypoxia-Activated BODIPY-Azo Anticancer Prodrug for Bimodal Chemo-Photodynamic Therapy

For cancer treatment, collaborative strategies have been the mainstream for overcoming the restrictions resulting from monotherapy. Combining chemotherapy with photodynamic therapy (PDT) has been shown to increase the antitumor effect and reduce side impacts. This study reports a hypoxia-activated prodrug BOD-Azo-single with a PDT agent and aniline mustard connected by the azo bond. With light illumination, BOD-Azo-single exhibited some PDT. Under hypoxic conditions, the azo bond cleaved and released BOD-3-single of higher phototoxicity and aniline mustard of chemotoxicity. In vivo therapeutic experiments showed that BOD-Azo-single with light significantly reduced A375 tumor proliferation with 92% TGI value. Overall, in this study, PDT was employed to address the adverse systemic toxicity of chemotherapy and the released chemotoxicity made up for the inefficiency of PDT in the hypoxic tumor microenvironment, introducing a new strategy for developing combined therapeutic agents to be advantageous to each other. Under a hypoxic tumor environment, BOD-3-single and aniline mustard exerted a strong synergistic effect (CI = 0.25), indicating that BOD-Azo-single is a real bimodal chemo-photodynamic therapeutic agent.

Radiation therapy-induced normal tissue damage: involvement of EMT pathways and role of FLASH-RT in reducing toxicities

Radiation therapy (RT) is fundamental to the fight against cancer because of its exceptional ability to target and destroy cancer cells. However, conventional radiation therapy can significantly affect the adjacent normal tissues, leading to fibrosis, inflammation, and decreased organ function. This tissue damage not only reduces the quality of life but also prevents the total elimination of cancer. The transformation of epithelial cells into mesenchymal-like cells, termed epithelial-mesenchymal transition (EMT), is essential for processes such as fibrosis, embryogenesis, and wound healing. Conventional radiation therapy increases the asymmetric activation of fibrotic and inflammatory pathways, and the resulting chronic fibrotic changes and organ dysfunction are linked to radiation-induced epithelial-mesenchymal transition. Recent advances in radiation therapy, namely flash radiation therapy (FLASH-RT), have the potential to widen the therapeutic index. Radiation delivered by FLASH-RT at very high dose rates (exceeding 40 Gy/s) can protect normal tissue from radiation-induced damage, a phenomenon referred to as the "FLASH effect". Preclinical studies have demonstrated that FLASH-RT successfully inhibits processes associated with fibrosis and epithelial-mesenchymal transition, mitigates damage to normal tissue, and enhances regeneration. Three distinct types of EMT have been identified: type-1, associated with embryogenesis; Type-2, associated with injury potential; and type-3, related with cancer spread. The regulation of EMT via pathways, including TGF-β/SMAD, WNT/β-catenin, and NF-κB, is essential for radiation-induced tissue remodelling. This study examined radiation-induced EMT, TGF-β activity, multiple signalling pathways in fibrosis, and the potential of FLASH-RT to reduce tissue damage. FLASH-RT is a novel approach to treat chronic tissue injury and fibrosis post-irradiation by maintaining epithelial properties and regulating mesenchymal markers including vimentin and N-cadherin. Understanding these pathways will facilitate the development of future therapies that can alleviate fibrosis, improve the efficacy of cancer therapy, and improve the quality of life of patients.

Omics-Enhanced Nanomedicine for Cancer Therapy

Cancer nanomedicine has emerged as a promising approach to overcome the limitations of conventional cancer therapies, offering enhanced efficacy and safety in cancer management. However, the inherent heterogeneity of tumors presents increasing challenges for the application of cancer nanomedicine in both diagnosis and treatment. This heterogeneity necessitates the integration of advanced and high-throughput analytical techniques to tailor nanomedicine strategies to individual tumor profiles. Omics technologies, encompassing genomics, epigenomics, transcriptomics, proteomics, metabolomics, and more, provide unparalleled insights into the molecular and cellular mechanisms underlying cancer. By dissecting tumor heterogeneity across multiple levels, these technologies offer robust support for the development of personalized and precise cancer nanomedicine strategies. In this review, the principles, techniques, and applications of key omics technologies are summarized. Especially, the synergistic integration of omics and nanomedicine in cancer therapy is explored, focusing on enhanced diagnostic accuracy, optimized therapeutic strategies and the assessment of nanomedicine-mediated biological responses. Moreover, this review addresses current challenges and outlines future directions in the field of omics-enhanced nanomedicine. By offering valuable insights and guidance, this review aims to advance the integration of omics with nanomedicine, ultimately driving improved diagnostic and therapeutic strategies for cancer.

Clinical translation of nanomedicine with integrated digital medicine and machine learning interventions

Nanomaterials based therapeutics transform the ways of disease prevention, diagnosis and treatment with increasing sophistications in nanotechnology at a breakneck pace, but very few could reach to the clinic due to inconsistencies in preclinical studies followed by regulatory hinderances. To tackle this, integrating the nanomedicine discovery with digital medicine provide technologies as tools of specific biological activity measurement. Hence, overcome the redundancies in nanomedicine discovery by the on-site data acquisition and analytics through integrating intelligent sensors and artificial intelligence (AI) or machine learning (ML). Integrated AI/ML wearable sensors directly gather clinically relevant biochemical information from the subject's body and process data for physicians to make right clinical decision(s) in a time and cost-effective way. This review summarizes insights and recommend the infusion of actionable big data computation enabled sensors in burgeoning field of nanomedicine at academia, research institutes, and pharmaceutical industries, with a potential of clinical translation. Furthermore, many blind spots are present in modern clinically relevant computation, one of which could prevent ML-guided low-cost new nanomedicine development from being successfully translated into the clinic was also discussed.

Nanomedomics

Nanomaterials have attractive physicochemical properties. A variety of nanomaterials such as inorganic, lipid, polymers, and protein nanoparticles have been widely developed for nanomedicine via chemical conjugation or physical encapsulation of bioactive molecules. Superior to traditional drugs, nanomedicines offer high biocompatibility, good water solubility, long blood circulation times, and tumor-targeting properties. Capitalizing on this, several nanoformulations have already been clinically approved and many others are currently being studied in clinical trials. Despite their undoubtful success, the molecular mechanism of action of the vast majority of nanomedicines remains poorly understood. To tackle this limitation, herein, this review critically discusses the strategy of applying multiomics analysis to study the mechanism of action of nanomedicines, named nanomedomics, including advantages, applications, and future directions. A comprehensive understanding of the molecular mechanism could provide valuable insight and therefore foster the development and clinical translation of nanomedicines.

Nanomaterials for light-mediated therapeutics in deep tissue

Light-mediated therapeutics, including photodynamic therapy, photothermal therapy and light-triggered drug delivery, have been widely studied due to their high specificity and effective therapy. However, conventional light-mediated therapies usually depend on the activation of light-sensitive molecules with UV or visible light, which have poor penetration in biological tissues. Over the past decade, efforts have been made to engineer nanosystems that can generate luminescence through excitation with near-infrared (NIR) light, ultrasound or X-ray. Certain nanosystems can even carry out light-mediated therapy through chemiluminescence, eliminating the need for external activation. Compared to UV or visible light, these 4 excitation modes penetrate more deeply into biological tissues, triggering light-mediated therapy in deeper tissues. In this review, we systematically report the design and mechanisms of different luminescent nanosystems excited by the 4 excitation sources, methods to enhance the generated luminescence, and recent applications of such nanosystems in deep tissue light-mediated therapeutics.

Polydopamine Nanostructure-Enhanced Water Interaction with pH-Responsive Manganese Sulfide Nanoclusters for Tumor Magnetic Resonance Contrast Enhancement and Synergistic Ferroptosis-Photothermal Therapy

Rational structure design benefits the development of efficient nanoplatforms for tumor theranostic application. In this work, a multifunctional polydopamine (PDA)-coated manganese sulfide (MnS) nanocluster was prepared. The polyhydroxy structure of PDA enhanced the water interaction with pH-responsive MnS nanoclusters via hydrogen bonds. At pH 5.5 conditions, the spin-lattice relaxation rate of MnS nanoclusters dramatically increased from 5.76 to 19.33 mM-1·s-1 after the PDA coating, which can be beneficial for efficient tumor magnetic resonance imaging. In addition, PDA endowed MnS nanoclusters with excellent biocompatibility and good photothermal conversion efficiency, which can be used for efficient tumor photothermal therapy (PTT). Furthermore, MnS nanoclusters possess the ability to release H2S in the acidic tumor microenvironment, effectively inhibiting mitochondrial respiration and adenosine triphosphate production. As a result, the expression of heat shock protein was obviously reduced, which can reduce the resistance of tumor cells to photothermal stimulation and enhance the efficacy of PTT. The released Mn2+ also displayed efficient peroxidase and glutathione oxidase-like activity, effectively inducing tumor cell ferroptosis and apoptosis at the same time. Therefore, this nanoplatform could be a potential nanotheranostic for magnetic resonance contrast enhancement and synergistic ferroptosis-PTT of tumors.

X-ray excited luminescent nanoparticles for deep photodynamic therapy

Photodynamic therapy (PDT), as a non-invasive treatment, has received wide attention because of its high selectivity and low side effects. However, traditional PDT is influenced by the excitation light source and the light penetration depth is limited, which can only be used for superficial epidermal tumor treatment, and it is still a great challenge for deep tumor treatment. In recent years, X-ray excitation photodynamic therapy (X-PDT) using penetrating X-rays as an external excitation source and X-ray excited luminescent nanoparticles (XLNP) as an energy transfer medium to indirectly excite photosensitizer (PS) has solved the problem of insufficient penetration depth in tissues and become a research hotspot in the field of deep tumor treatment. In this review, the recent research progress of nanoparticles for efficient X-PDT, listing different types of XLNP and luminescence enhancement strategies. The loading method of PS is highlighted to achieve efficient energy transfer by regulating the intermolecular distance between both XLNP/PS. In addition, the water-soluble modification of XLNP surface is discussed and different hydrophilic modification methods are proposed to provide reference ideas for improving the dispersibility and biocompatibility of XLNP in aqueous solution. Finally, the therapeutic effects about X-PDT are discussed, and the current challenges and future perspectives for its clinical applications are presented.

Combining Pr3+-Doped Nanoradiosensitizers and Endogenous Protoporphyrin IX for X-ray-Mediated Photodynamic Therapy of Glioblastoma Cells

Glioblastoma multiforme is an aggressive type of brain cancer with high recurrence rates due to the presence of radioresistant cells remaining after tumor resection. Here, we report the development of an X-ray-mediated photodynamic therapy (X-PDT) system using NaLuF₄:25% Pr³⁺ radioluminescent nanoparticles in conjunction with protoporphyrin IX (PPIX), an endogenous photosensitizer that accumulates selectively in cancer cells. Conveniently, 5-aminolevulinic acid (5-ALA), the prodrug that is administered for PDT, is the only drug approved for fluorescence-guided resection of glioblastoma, enabling dual detection and treatment of malignant cells. NaLuF₄:Pr³⁺ nanoparticles were synthesized and spectroscopically evaluated at a range of Pr³⁺ concentrations. This generated radioluminescent nanoparticles with strong emissions from the ¹S₀ excited state of Pr³⁺, which overlaps with the Soret band of PPIX to perform photodynamic therapy. The spectral overlap between the nanoparticles and PPIX improved treatment outcomes for U251 cells, which were used as a model for the thin tumor margin. In addition to sensitizing PPIX to induce X-PDT, our nanoparticles exhibit strong radiosensitizing properties through a radiation dose-enhancement effect. We evaluate the effects of the nanoparticles alone and in combination with PPIX on viability, death, stress, senescence, and proliferation. Collectively, our results demonstrate this as a strong proof of concept for nanomedicine.

Energy Partitioning in Multicomponent Nanoscintillators for Enhanced Localized Radiotherapy

Multicomponent nanomaterials consisting of dense scintillating particles functionalized by or embedding optically active conjugated photosensitizers (PSs) for cytotoxic reactive oxygen species (ROS) have been proposed in the last decade as coadjuvant agents for radiotherapy of cancer. They have been designed to make scintillation-activated sensitizers for ROS production in an aqueous environment under exposure to ionizing radiations. However, a detailed understanding of the global energy partitioning process occurring during the scintillation is still missing, in particular regarding the role of the non-radiative energy transfer between the nanoscintillator and the conjugated moieties which is usually considered crucial for the activation of PSs and therefore pivotal to enhance the therapeutic effect. We investigate this mechanism in a series of PS-functionalized scintillating nanotubes where the non-radiative energy transfer yield has been tuned by control of the intermolecular distance between the nanotube and the conjugated system. The obtained results indicate that non-radiative energy transfer has a negligible effect on the ROS sensitization efficiency, thus opening the way to the development of different architectures for breakthrough radiotherapy coadjutants to be tested in clinics.

An X-ray activatable gold nanorod encapsulated liposome delivery system for mitochondria-targeted photodynamic therapy (PDT)

In this work, we developed a mitochondria-targeted nanomaterial for neoadjuvant X-ray-triggered photodynamic therapy of rectal cancer. Herein, we designed a biodegradable liposome incorporating a photosensitizer, verteporfin, to generate X-ray-induced reactive oxygen species, gold nanorods as radiation enhancers, and triphenylphosphonium as the mitochondrial targeting moiety. The average size of the nanocarrier was about 150 nm. Due to the synergetic effect between X-ray and a combination of verteporfin and gold nanorods, as well as precise site-targeted TPP-modified liposomal nanocarriers, our nanoconjugates generated sufficient cytotoxic singlet oxygen within the mitochondria under X-ray irradiation, triggering the loss of membrane potential and mitochondria-related apoptosis of cancer cells.

Enhancement of Light and X-ray Charging in Persistent Luminescence Nanoparticle Scintillators Zn2SiO4:Mn2+, Yb3+, Li. ACS APPLIED MATERIALS & INTERFACES 2023;15:21228-21238. [PMID: 37078901 DOI: 10.1021/acsami.3c00664]

Persistent luminescence nanoparticle scintillators (PLNS) have been attempted for X-ray-induced photodynamic therapy (X-PDT) because persistent luminescence after ceasing radiation can make PLNS use less cumulative irradiation time and dose to generate the same amount of reactive oxygen species (ROS) compared with conventional scintillators to combat cancer cells. However, excessive surface defects in PLNS reduce the luminescence efficiency and quench the persistent luminescence, which is fatal to the efficacy of X-PDT. Herein, the PLNS of SiO₂@Zn₂SiO₄:Mn²⁺, Yb³⁺, Li⁺ was designed by the energy trap engineering and synthesized by a simple template method, which has excellent X-ray and UV-excited persistent luminescence and continuously tunable emission spectra from 520 to 550 nm. Its luminescence intensity and afterglow time are more than 7 times that of the reported Zn₂SiO₄:Mn²⁺ used for X-PDT. By loading a Rose Bengal (RB) photosensitizer, an effective persistent energy transfer from the PLNS to photosensitizer is observed even after the removal of X-ray irradiation. The X-ray dose of nanoplatform SiO₂@Zn₂SiO₄:Mn²⁺, Yb³⁺, Li⁺@RB in X-PDT of HeLa cancer cells was reduced to 0.18 Gy compared to the X-ray dose of 1.0 Gy for Zn₂SiO₄:Mn for X-PDT. This indicates that the Zn₂SiO₄:Mn²⁺, Yb³⁺, Li⁺ PLNS have great potential for X-PDT applications.

Catalytic nanotechnology of X-ray photodynamics for cancer treatments

Photodynamic therapy (PDT) has been applied in cancer treatment because of its high selectivity, low toxicity, and non-invasiveness. However, the limited penetration depth of the light still hampers from reaching deep-seated tumors. Considering the penetrating ability of high-energy radiotherapy, X-ray-induced photodynamic therapy (X-PDT) has evolved as an alternative to overcome tissue blocks. As the basic principle of X-PDT, X-rays stimulate the nanoparticles to emit scintillating or persistent luminescence and further activate the photosensitizers to generate reactive oxygen species (ROS), which would cause a series of molecular and cellular damages, immune response, and eventually break down the tumor tissue. In recent years, catalytic nanosystems with unique structures and functions have emerged that can enhance X-PDT therapeutic effects via an immune response. The anti-cancer effect of X-PDT is closely related to the following factors: energy conversion efficiency of the material, the radiation dose of X-rays, quantum yield of the material, tumor resistance, and biocompatibility. Based on the latest research in this field and the classical theories of nanoscience, this paper systematically elucidates the current development of the X-PDT and related immunotherapy, and highlights its broad prospects in medical applications, discussing the connection between fundamental science and clinical translation.

Recent Progress and Trends in X-ray-Induced Photodynamic Therapy with Low Radiation Doses

The prominence of photodynamic therapy (PDT) in treating superficial skin cancer inspires innovative solutions for its congenitally deficient shadow penetration of the visible-light excitation. X-ray-induced photodynamic therapy (X-PDT) has been proven to be a successful technique in reforming the conventional PDT for deep-seated tumors by creatively utilizing penetrating X-rays as external excitation sources and has witnessed rapid developments over the past several years. Beyond the proof-of-concept demonstration, recent advances in X-PDT have exhibited a trend of minimizing X-ray radiation doses to quite low values. As such, scintillating materials used to bridge X-rays and photosensitizers play a significant role, as do diverse well-designed irradiation modes and smart strategies for improving the tumor microenvironment. Here in this review, we provide a comprehensive summary of recent achievements in X-PDT and highlight trending efforts using low doses of X-ray radiation. We first describe the concept of X-PDT and its relationships with radiodynamic therapy and radiotherapy and then dissect the mechanism of X-ray absorption and conversion by scintillating materials, reactive oxygen species evaluation for X-PDT, and radiation side effects and clinical concerns on X-ray radiation. Finally, we discuss a detailed overview of recent progress regarding low-dose X-PDT and present perspectives on possible clinical translation. It is expected that the pursuit of low-dose X-PDT will facilitate significant breakthroughs, both fundamentally and clinically, for effective deep-seated cancer treatment in the near future.

Advanced techniques for performing photodynamic therapy in deep-seated tissues

Photodynamic therapy (PDT) is a promising localized cancer treatment modality. It has been used successfully to treat a range of dermatological conditions with comparable efficacy to conventional treatments. However, some drawbacks limit the clinical utility of PDT in treating deep-seated tumors. Notably, the penetration limitation of UV and visible light, commonly applied to activate photosensitizers, makes PDT incompetent in treating deep-seated tumors. Development in light delivery technologies, especially fiber optics, led to improved clinical strategies for accessing deep tissues for irradiation. However, PDT efficacy issues remained partly due to light penetration limitations. In this review, we first summarized the current PDT applications for deep-seated tumor treatment. Then, the most recent progress in advanced techniques to overcome the light penetration limitation in PDT, including using functional nanomaterials that can either self-illuminate or be activated by near-infrared (NIR) light and X-rays as transducers, and implantable light delivery devices were discussed. Finally, current challenges and future opportunities of these technologies were discussed, which we hope may inspire the development of more effective techniques to enhance PDT efficacy against deep-seated tumors.

Combining Radiotherapy (RT) and Photodynamic Therapy (PDT): Clinical Studies on Conventional RT-PDT Approaches and Novel Nanoparticle-Based RT-PDT Approaches under Preclinical Evaluation

Radiotherapy (RT) is the primary standard of care for many locally advanced cancers. Often times, however, the efficacy of RT is limited due to radio-resistance that cancer cells develop. Photodynamic therapy (PDT) has gained importance as an alternative local therapy. Because its mechanism involves minimal acquired resistance, PDT is a useful adjunct to RT. This review discusses recent advances in combining RT with PDT for cancer treatment. In the first part of this review, we will discuss clinical trials on RT + PDT combination therapies. All these approaches suffer from the same inherent limitations as any current PDT methods; (i) visible light has a short penetration depth in human tissue (<∼10 mm), and (ii) it is difficult to illuminate the entire tumor homogeneously by external/interstitial laser irradiation. To address these limitations, scintillating nanoparticle-mediated RT-PDT approaches have been explored in which nanoparticles convert X-rays (RT) into visible light (PDT); high-energy X-rays can reach deep into the body to irradiate cancers uniformly and precisely. The second part of this review will discuss recent efforts in developing and applying nanoparticles for RT-PDT applications.

Importance of Rose Bengal Loaded with Nanoparticles for Anti-Cancer Photodynamic Therapy

Rose Bengal (RB) is a photosensitizer (PS) used in anti-cancer and anti-bacterial photodynamic therapy (PDT). The specific excitation of this PS allows the production of singlet oxygen and oxygen reactive species that kill bacteria and tumor cells. In this review, we summarize the history of the use of RB as a PS coupled by chemical or physical means to nanoparticles (NPs). The studies are divided into PDT and PDT excited by X-rays (X-PDT), and subdivided on the basis of NP type. On the basis of the papers examined, it can be noted that RB used as a PS shows remarkable cytotoxicity under the effect of light, and RB loaded onto NPs is an excellent candidate for nanomedical applications in PDT and X-PDT.

X-ray triggered pea-shaped LuAG:Mn/Ca nano-scintillators and their applications for photodynamic therapy

Photodynamic therapy (PDT) is a new minimally invasive technology for disease diagnosis and treatment. However, the biological tissue attenuation of visible light renders the depth of its penetration in tissues quite modest, which significantly restricts its therapeutic applicability. Therefore, it is an essential but yet a difficult task to enhance the X-ray sensitization impact while concurrently limiting the tissue scattering by the rational design of novel biological vectors. Herein, a novel Lu3Al5O12:Mn/Ca-Ce6@SiO2 nanoparticle system (LAMCCS) based on a pea-shaped LuAG:Mn/Ca nano-scintillator (LAMC) activating photosensitizer agent (Ce6) was designed. Due to the high radiosensitization of LAMC nano-scintillators and efficient energy conversion efficiency between LAMC and Ce6, more singlet oxygen (1O2) could be generated to efficiently damage DNA fragments and reveal a good effect of inhibiting the long-term proliferation of tumor cells in vitro. Significantly, synergistic therapy with PDT/radiotherapy (RT) and from LAMCCS nanocomposites may still maintain a high tumor growth inhibition rate of 72% than single RT of 10% in vivo. Owing to their excellent ability for X-ray sensitization and energy conversion, LAMCCS nanocomposites may have significant tumor growth suppression rates under lower X-ray dose irradiation due to their outstanding X-ray sensitization and energy conversion capabilities, which may open up a new avenue for the advancement of cancer therapy.

Design Principles of Hybrid Nanomaterials for Radiotherapy Enhanced by Photodynamic Therapy

Radiation (RT) remains the most frequently used treatment against cancer. The main limitation of RT is its lack of specificity for cancer tissues and the limited maximum radiation dose that can be safely delivered without damaging the surrounding healthy tissues. A step forward in the development of better RT is achieved by coupling it with other treatments, such as photodynamic therapy (PDT). PDT is an anti-cancer therapy that relies on the light activation of non-toxic molecules-called photosensitizers-to generate ROS such as singlet oxygen. By conjugating photosensitizers to dense nanoscintillators in hybrid architectures, the PDT could be activated during RT, leading to cell death through an additional pathway with respect to the one activated by RT alone. Therefore, combining RT and PDT can lead to a synergistic enhancement of the overall efficacy of RT. However, the involvement of hybrids in combination with ionizing radiation is not trivial: the comprehension of the relationship among RT, scintillation emission of the nanoscintillator, and therapeutic effects of the locally excited photosensitizers is desirable to optimize the design of the hybrid nanoparticles for improved effects in radio-oncology. Here, we discuss the working principles of the PDT-activated RT methods, pointing out the guidelines for the development of effective coadjutants to be tested in clinics.

Application of Mesoporous Silica Nanoparticles in Cancer Therapy and Delivery of Repurposed Anthelmintics for Cancer Therapy

This review focuses on the biomedical application of mesoporous silica nanoparticles (MSNs), mainly focusing on the therapeutic application of MSNs for cancer treatment and specifically on overcoming the challenges of currently available anthelmintics (e.g., low water solubility) as repurposed drugs for cancer treatment. MSNs, due to their promising features, such as tunable pore size and volume, ability to control the drug release, and ability to convert the crystalline state of drugs to an amorphous state, are appropriate carriers for drug delivery with the improved solubility of hydrophobic drugs. The biomedical applications of MSNs can be further improved by the development of MSN-based multimodal anticancer therapeutics (e.g., photosensitizer-, photothermal-, and chemotherapeutics-modified MSNs) and chemical modifications, such as poly ethyleneglycol (PEG)ylation. In this review, various applications of MSNs (photodynamic and sonodynamic therapies, chemotherapy, radiation therapy, gene therapy, immunotherapy) and, in particular, as the carrier of anthelmintics for cancer therapy have been discussed. Additionally, the issues related to the safety of these nanoparticles have been deeply discussed. According to the findings of this literature review, the applications of MSN nanosystems for cancer therapy are a promising approach to improving the efficacy of the diagnostic and chemotherapeutic agents. Moreover, the MSN systems seem to be an efficient strategy to further help to decrease treatment costs by reducing the drug dose.

Catalytic radiosensitization: Insights from materials physicochemistry

Radiotherapy is indispensable in clinical cancer treatment, but because both tumor and normal tissues have similar sensitivity to X-rays, their clinical curative effect is intrinsically limited. Advanced nanomaterials and nanotechnologies have been developed for radiotherapy sensitization, typically employing high atomic number (high-Z) materials to enhance the energy deposition of X-rays in tumor tissues, but the efficiency is largely limited by the toxicity of heavy metals. A new and promising approach for radiosensitization is catalytic radiosensitization, which takes advantage of the catalytic activity of nanomaterials triggered by radiation. The efficiency of catalytic radiosensitization can be greatly enhanced by electron modulation and energy conversion of nanocatalysts upon X-ray irradiation, further enhancing the clinical curative effect. In this review, we highlight the challenges and opportunities in cancer radiosensitization, discuss novel approaches to catalytic radiosensitization, and finally describe the development of catalytic radiosensitization based on an in-depth understanding of radio-nano interactions and catalysis-biological interactions.

Nanomaterials-assisted metabolic analysis toward in vitro diagnostics

In vitro diagnostics (IVD) has played an indispensable role in healthcare system by providing necessary information to indicate disease condition and guide therapeutic decision. Metabolic analysis can be the primary choice to facilitate the IVD since it characterizes the downstream metabolites and offers real-time feedback of the human body. Nanomaterials with well-designed composition and nanostructure have been developed for the construction of high-performance detection platforms toward metabolic analysis. Herein, we summarize the recent progress of nanomaterials-assisted metabolic analysis and the related applications in IVD. We first introduce the important role that nanomaterials play in metabolic analysis when coupled with different detection platforms, including electrochemical sensors, optical spectrometry, and mass spectrometry. We further highlight the nanomaterials-assisted metabolic analysis toward IVD applications, from the perspectives of both the targeted biomarker quantitation and untargeted fingerprint extraction. This review provides fundamental insights into the function of nanomaterials in metabolic analysis, thus facilitating the design of next-generation diagnostic devices in clinical practice.

Progress of Nanomaterials in Photodynamic Therapy Against Tumor

Photodynamic therapy (PDT) is an advanced therapeutic strategy with light-triggered, minimally invasive, high spatiotemporal selective and low systemic toxicity properties, which has been widely used in the clinical treatment of many solid tumors in recent years. Any strategies that improve the three elements of PDT (light, oxygen, and photosensitizers) can improve the efficacy of PDT. However, traditional PDT is confronted some challenges of poor solubility of photosensitizers and tumor suppressive microenvironment. To overcome the related obstacles of PDT, various strategies have been investigated in terms of improving photosensitizers (PSs) delivery, penetration of excitation light sources, and hypoxic tumor microenvironment. In addition, compared with a single treatment mode, the synergistic treatment of multiple treatment modalities such as photothermal therapy, chemotherapy, and radiation therapy can improve the efficacy of PDT. This review summarizes recent advances in nanomaterials, including metal nanoparticles, liposomes, hydrogels and polymers, to enhance the efficiency of PDT against malignant tumor.

Recent Advance of Nanomaterial-Mediated Tumor Therapies in the Past Five Years

Cancer has posed a major threat to human life and health with a rapidly increasing number of patients. The complexity and refractory of tumors have brought great challenges to tumor treatment. In recent years, nanomaterials and nanotechnology have attracted more attention and greatly improved the efficiency of tumor therapies and significantly prolonged the survival period, whether for traditional tumor treatment methods such as radiotherapy, or emerging methods, such as phototherapy and immunotherapy, sonodynamic therapy, chemodynamic therapy and RNA interference therapeutics. Various monotherapies have obtained positive results, while combination therapies are further proposed to prevent incomplete eradication and recurrence of tumors, strengthen tumor killing efficacy with minimal side effects. In view of the complementary promotion effects between different therapies, it is vital to utilize nanomaterials as the link between monotherapies to achieve synergistic performance. Further development of nanomaterials with efficient tumor-killing effect and better biosafety is more in line with the needs of clinical treatment. In a word, the development of nanomaterials provides a promising way for tumor treatment, and here we will review the emerging nanomaterials towards radiotherapy, phototherapy and immunotherapy, and summarized the developed nanocarriers applied for the tumor combination therapies in the past 5 years, besides, the advances of some other novel therapies such as sonodynamic therapy, chemodynamic therapy, and RNA interference therapeutics have also been mentioned.

Multifunctional liposome for photoacoustic/ultrasound imaging-guided chemo/photothermal retinoblastoma therapy

Retinoblastoma (RB) is a malignant intraocular neoplasm that occurs in children. Diagnosis and therapy are frequently delayed, often leading to metastasis, which necessitates effective imaging and treatment. In recent years, the use of nanoplatforms allowing both imaging and targeted treatment has attracted much attention. Herein, we report a novel nanoplatform folate-receptor (FR) targeted laser-activatable liposome termed FA-DOX-ICG-PFP@Lip, which is loaded with doxorubicin (DOX)/indocyanine green (ICG) and liquid perfluoropentane (PFP) for photoacoustic/ultrasound (PA/US) dual-modal imaging-guided chemo/photothermal RB therapy. The dual-modal imaging capability, photothermal conversion under laser irradiation, biocompatibility, and antitumor ability of these liposomes were appraised. The multifunctional liposome showed a good tumor targeting ability and was efficacious as a dual-modality contrast agent both in vivo and in vitro. When laser-irradiated, the liposome converted light energy to heat. This action caused immediate destruction of tumor cells, while simultaneously initiating PFP phase transformation to release DOX, resulting in both photothermal and chemotherapeutic antitumor effects. Notably, the FA-DOX-ICG-PFP@Lip showed good biocompatibility and no systemic toxicity was observed after laser irradiation in RB tumor-bearing mice. Hence, the FA-DOX-ICG-PFP@Lip shows great promise for dual-modal imaging-guided chemo/photothermal therapy, and may have significant value for diagnosing and treating RB.

A scintillating nanoplatform with upconversion function for the synergy of radiation and photodynamic therapies for deep tumors

Collaborative therapy is regarded as an effective approach in increasing the therapeutic efficacy of cancer. In this work, we have proposed and validated the concept of upconversion lumienscence image guided synergy of photodynamic therapy (PDT) and radiotherapy (RT) for deep cancer, via a specially designed nanoplatform integrating near infrared (NIR) light activated luminescence upconversion and X-ray induced scintillation. Upon NIR light irradiation, the nanoplatform emits highly monochromatic red light solely for imaging the targeted cancer cells without triggering therapy; however, when the irradiation turns to a low dose of X-rays, scintillation will occur which induces effectively the PDT destroying the cancer cells together with X-ray induced RT. The novel theranostic nanoplatform is constructed in such a way that the interactions between the upconversion core and the outmost scintillating shell are blocked effectively by an inert layer between them. This structural design not only enables a nearly perfect excitation energy delivery (∼100% at a spectral overlapping wavelength of ∼540 nm) from the outermost scintellating layer to the surface-anchored photosensitizers and so a maximum yield of radical oxygen species, but also achieves a strong NIR induced upconversion luminescence for imaging. Since PDT and RT attack different parts of a cancer cell, this synergy is more effective in destroying cancer than a single therapy, resulting in the reduction of the X-ray irradiation dosage. As a proof of principle, the theranostic effect is validated by in vitro and in vivo experiments, exhibiting the great potential of this sort of nanoplatform in deep cancer treatment.

Development of nanotechnology-mediated precision radiotherapy for anti-metastasis and radioprotection

Radiotherapy (RT), including external beam RT and internal radiation therapy, uses high-energy ionizing radiation to kill tumor cells.

Facile synthesis of rare earth-doped CeF3 two-dimensional nanosheets and their application in ratiometric luminescence temperature sensing

Rare earth-doped CeF3 two-dimensional nanosheets have been successfully synthesized and their potential application as a ratiometric luminescent thermometer.

Modulating electron population pathways for time-dependent dynamic multicolor displays

Multicolor luminescent nanoparticles (NPs) show several potential emerging applications. In this work, we provide a new route that integrates the afterglow and upconversion (UC) that originate in a single activator to achieve color variations without the modulation of any other parameters. The Er³⁺ ions in Na₃HfF₇:Yb/Er NPs exhibit bright green afterglow upon X-ray irradiation and single-band red UC under 980 nm laser excitation, which are attributed to the significantly different electron population pathways. The UC intensity is stable and the afterglow decreases gradually over time, thus the output color is clearly changed from green to red naturally via illuminating the pre-X-ray-irradiated NPs with a 980 nm laser. Furthermore, the fine emission profiles of Er³⁺, Ho³⁺ and Tm³⁺ are achieved upon X-ray irradiation. Our results develop a new approach for time-dependent dynamic color displays and a simple route to revealing the electronic fine structures of lanthanide activators at room temperature.

Highly Efficient NaGdF4:Ce/Tb Nanoscintillator with Reduced Afterglow and Light Scattering for High-Resolution X-ray Imaging

Scintillation-based X-ray excited optical luminescence (XEOL) imaging shows great potential applications in the fields of industrial security inspection and medical diagnosis. It is still a great challenge to achieve scintillators simultaneously with low toxicity, high stability, strong XEOL intensity, and weak afterglow as well as simple device processibility with weak light scattering. Herein, we introduce ethylenediaminetetraacetate (EDTA)-capped NaGdF₄:10Ce/18Tb nanoparticles (NPs) as a highly sensitive nanoscintillator, which meets all of the abovementioned challenges. These NPs show comparable XEOL intensity to the commercial CsI (Tl) single crystal in the green region. We propose a mechanism that involves a new electron-captured path by Ce³⁺ ions and the promotion of energy migration from a trap center to surface quenchers via a Gd³⁺ sublattice, which greatly reduces the population in traps to produce significant reduction of afterglow. Moreover, by employing an ultrathin transparent NaGdF₄:10Ce/18Tb film (0.045 mm) as a nanoscintillator screen for XEOL imaging, a high spatial resolution of 18.6 lp mm^-1 is realized owing to the greatly limited optical scattering, which is superior to the commercial CsI (TI) scintillator and most reported lead halide perovskites. We demonstrate that doping Ce³⁺ ions can greatly limit X-ray-activated afterglow, enabling to use an ultrathin transparent fluoride NP-based nanoscintillator screen for high-quality XEOL imaging of various objects such as an electronics chip and biological tissue.

Antiangiogenesis Combined with Inhibition of the Hypoxia Pathway Facilitates Low-Dose, X-ray-Induced Photodynamic Therapy

X-ray-induced photodynamic therapy (XPDT) is overwhelmingly superior in treating deep-seated cancers. However, limitations remain, owing to a combination of the poor scintillation performance of the nanoscintillator, low energy transfer efficiency of the therapeutic nanoplatform, and hypoxic environment presented in the tumor tissue. Collectively, these reduce the curative effect of XPDT. Here, we report a highly efficient, low-dose XPDT realized by systematic optimization from scintillation efficiency, nanoplatform structure, to therapeutic approach. We developed a biocompatible, codoped CaF₂ nanoscintillator that emitted sufficiently green radioluminescence that was bright enough to be seen by the naked eye. Using dendrimers as a framework, we built a nanoplatform featuring a dual-core-satellite architecture, which enabled both procedurally and spatially separate dual-loading of therapeutic agents. This strategy allowed for the fabrication of a combined XPDT and antiangiogenic therapy, resulting in a therapeutic system capable of simultaneous tumor attacks. After exposure to ultralow dose radiation, XPDT resulted in marked tumor reduction while the antiangiogenic drug effectively blocked tumor vascularization exacerbated by XPDT-mediated hypoxia, rendering a pronounced synergy effect. This system also showed high biosafety, as the agents adopted had been used clinically and both Ca and F elements were widespread in the human body. Taken together, the findings presented here provided a reference for the construction of complex, multiloading architecture in coordination with structural complexity and functional diversification. This work provided a safer and more robust application of the combined XPDT and antiangiogenesis in future clinical treatment settings.

Nanomaterials for Deep Tumor Treatment

According to statistics, cancer is the second leading cause of death in the world. Thus, it is important to solve this medical and social problem by developing new effective methods for cancer treatment. An alternative to more well-known approaches, such as radiotherapy and chemotherapy, is photodynamic therapy (PDT), which is limited to the shallow tissue penetration (< 1 cm) of visible light. Since the PDT process can be initiated in deep tissues by X-ray irradiation (X-ray induced PDT, or XPDT), it has a great potential to treat tumors in internal organs. The article discusses the principles of therapies. The main focus is on various nanoparticles used with or without photosensitizers, which allow the conversion of X-ray irradiation into UV-visible light. Much attention is given to the synthesis of nanoparticles and analysis of their characteristics, such as size and spectral features. The results of in vitro and in vivo experiments are also discussed.

An Update on Mesoporous Silica Nanoparticle Applications in Nanomedicine

The efficient and safe delivery of therapeutic drugs, proteins, and nucleic acids are essential for meaningful therapeutic benefits. The field of nanomedicine shows promising implications in the development of therapeutics by delivering diagnostic and therapeutic compounds. Nanomedicine development has led to significant advances in the design and engineering of nanocarrier systems with supra-molecular structures. Smart mesoporous silica nanoparticles (MSNs), with excellent biocompatibility, tunable physicochemical properties, and site-specific functionalization, offer efficient and high loading capacity as well as robust and targeted delivery of a variety of payloads in a controlled fashion. Such unique nanocarriers should have great potential for challenging biomedical applications, such as tissue engineering, bioimaging techniques, stem cell research, and cancer therapies. However, in vivo applications of these nanocarriers should be further validated before clinical translation. To this end, this review begins with a brief introduction of MSNs properties, targeted drug delivery, and controlled release with a particular emphasis on their most recent diagnostic and therapeutic applications.

Screening of metabolites in the treatment of liver cancer xenografts HepG2/ADR by psoralen-loaded lipid nanoparticles

OBJECTIVE

Our study aimed to find potential biomarkers for drug resistance in liver cancer cells using metabolomics and further to evaluate the potential of psoralen-loaded polymer lipid nanoparticles (PSO-PLNs) to reverse the resistance of cells to doxorubicin.

METHODS

We used LC-MS-based non-targeted metabolomics, also known as global metabolite profiling, to screen in serum and urine of mice engrafted with a liver cancer cell line sensitive (HepG2/S) or resistant to doxorubicin (HepG2/ADR) for differentially regulated metabolites. We subsequently quantified the abundance of these metabolites in serum and the urine of mice. The mice were engrafted with HepG2 cells resistant against doxorubicin and were treated with I) doxorubicin, II) a combination of doxorubicin and psoralen and III) a combination of doxorubicin and psoralen packed in polymer lipid nanoparticles.

RESULTS

Metabolites found to be differentially present in urine of mice engrafted with resistant HepG2 cells were: hippuric acid, hyaluronic acid, pantothenic acid, and betaine; retinoic acid and α-linolenic acid were found to be reduced in serum samples of mice with HepG2 cells resistant to doxorubicin. The targeted analysis showed that the degree of regression of metabolic markers in groups differed: treatment group 2 had stronger degree of regression than treatment group 1 and the negative control group had the smallest, which indicates that the PSO-PLNs have superior properties compared with other treatments.

CONCLUSION

Psoralen reverses drug resistance of liver cancer cells and its efficacy can be increased by encapsulation in polymer lipid nanoparticles.

Janus Nanoparticles: From Fabrication to (Bio)Applications

Janus nanoparticles (JNPs) refer to the integration of two or more chemically discrepant composites into one structure system. Studies into JNPs have been of significant interest due to their interesting characteristics stemming from their asymmetric structures, which can integrate different functional properties and perform more synergetic functions simultaneously. Herein, we present recent progress of Janus particles, comprehensively detailing fabrication strategies and applications. First, the classification of JNPs is divided into three blocks, consisting of polymeric composites, inorganic composites, and hybrid polymeric/inorganic JNPs composites. Then, the fabrication strategies are alternately summarized, examining self-assembly strategy, phase separation strategy, seed-mediated polymerization, microfluidic preparation strategy, nucleation growth methods, and masking methods. Finally, various intriguing applications of JNPs are presented, including solid surfactants agents, micro/nanomotors, and biomedical applications such as biosensing, controlled drug delivery, bioimaging, cancer therapy, and combined theranostics. Furthermore, challenges and future works in this field are provided.

A Versatile Strategy for Constructing Ratiometric Upconversion Luminescent Probe with Sensitized Emission of Energy Acceptor

When fabricating ratiometric optical probes using lanthanide-doped upconversion nanoparticles (UCNPs), which are promising luminescent materials that have widely been utilized in biosensing and bioimaging as energy donors, it is still a challenge to obtain the emission signal of energy acceptors with reasons unclear so far. Herein, we reveal that the energy-transfer efficiency and brightness of UCNPs as well as the aggregation-caused quenching (ACQ) of energy accepting dyes are the main factors restricting the emission of energy acceptors, and we have circumvented this problem by modulating the structure of UCNPs and the assembly manner of the energy donor-acceptor pair. On this basis, a proof-of-concept ratiometric upconversion nanoprobe was constructed for hydrogen sulfide (H₂S) detection with an elaborate dye Fl-1 as an energy acceptor. As the H₂S concentration increased, the emission intensity of Fl-1 at 525 nm increased gradually, accompanied by a decrease of upconversion luminescence at 480 nm, thus providing a ratiometric signal of F₄₈₀/F₅₂₅ dependent on the H₂S concentration. This probe was able to track H₂S in living cells and zebrafish and visualize the H₂S level of mice in physiological processes.

Investigating the reactive oxygen species production of Rose Bengal and Merocyanine 540-loaded radioluminescent nanoparticles

Radioluminescent nanomaterials have garnered significant attention in the past decade due to their potential to perform X-ray mediated photodynamic therapy (X-PDT). Many of these materials are assumed to produce singlet oxygen based on a single assay. Herein we demonstrate that multiple assays are required to confidently determine whether singlet oxygen or other reactive oxygen species are being produced through type I or type II PDT mechanisms. Rose Bengal and Merocyanine 540 photosensitizers were loaded into mesoporous silica-coated NaLuF4:Dy3+,Gd3+ nanoparticles and the combination of ABDA, DPBF, and NaN3 assays along with electron paramagnetic resonance were employed to determine that superoxide and hydroxyl radicals were exclusively produced from this system under X-ray excitation. Knowledge of the correct PDT mechanism is crucial for informing what types of disease may be best suited for treatment using PDT nanosystems.

Emerging Nanomedicine-Enabled/Enhanced Nanodynamic Therapies beyond Traditional Photodynamics

The rapid knowledge growth of nanomedicine and nanobiotechnology enables and promotes the emergence of distinctive disease-specific therapeutic modalities, among which nanomedicine-enabled/augmented nanodynamic therapy (NDT), as triggered by either exogenous or endogenous activators on nanosensitizers, can generate reactive radicals for accomplishing efficient disease nanotherapies with mitigated side effects and endowed disease specificity. As one of the most representative modalities of NDT, traditional light-activated photodynamics suffers from the critical and unsurmountable issues of the low tissue-penetration depth of light and the phototoxicity of the photosensitizers. To overcome these obstacles, versatile nanomedicine-enabled/augmented NDTs have been explored for satisfying varied biomedical applications, which strongly depend on the physicochemical properties of the involved nanomedicines and nanosensitizers. These distinctive NDTs refer to sonodynamic therapy (SDT), thermodynamic therapy (TDT), electrodynamic therapy (EDT), piezoelectric dynamic therapy (PZDT), pyroelectric dynamic therapy (PEDT), radiodynamic therapy (RDT), and chemodynamic therapy (CDT). Herein, the critical roles, functions, and biological effects of nanomedicine (e.g., sonosensitizing, photothermal-converting, electronic, piezoelectric, pyroelectric, radiation-sensitizing, and catalytic properties) for enabling the therapeutic procedure of NDTs, are highlighted and discussed, along with the underlying therapeutic principle and optimization strategy for augmenting disease-therapeutic efficacy and biosafety. The present challenges and critical issues on the clinical translations of NDTs are also discussed and clarified.

Mesoporous Nanostructures Encapsulated with Metallic Nanodots for Smart SERS Sensing

In virtue of uniform mesopores and core-shell nanoarchitectures, metallic nanodot-encapsulated hollow mesoporous nanostructures have shown promising potential in various applications. However, their fabrication with versatile tunability of the encapsulated metallic content has been a challenge. Herein, we have prepared metallic nanodot-encapsulated hollow mesoporous silica nanoparticles (M-HMSNPs) with adjustable inner metallic components. The sacrificial template of polystyrene (PS) nanoparticles precoated with metals (Au/Ag/Pt) is fully wrapped with mesoporous silica (mSiO₂). The metallic nanodots are formed during the template removal process by calcination. The type and content of the encapsulated nanodots can be readily and precisely controlled by the initially deposited metallic layers. We demonstrate the application of the gold (Au) nanodot-loaded HMSNPs (denoted Au-HMSNPs) as smart surface-enhanced Raman spectroscopy (SERS) probes, which can screen between big molecules and small analytes. With the aid of a Raman reporter, the SERS probe can successfully quantify H₂O₂, which is used to distinguish cancer cells in vitro. Further integrated with enzymes, the SERS chips of specificity are prepared and used to detect corresponding substrates of glucose and uric acid, responsively. Besides SERS sensing, the current strategy can inspire future development of many other M-HMSNPs for various applications such as catalysis, energy storage, theranostics, etc.

Recent Advances in Photodynamic Therapy for Deep-Seated Tumors with the Aid of Nanomedicine

Photodynamic therapy (PDT) works through photoactivation of a specific photosensitizer (PS) in a tumor in the presence of oxygen. PDT is widely applied in oncology to treat various cancers as it has a minimally invasive procedure and high selectivity, does not interfere with other treatments, and can be repeated as needed. A large amount of reactive oxygen species (ROS) and singlet oxygen is generated in a cancer cell during PDT, which destroys the tumor effectively. However, the efficacy of PDT in treating a deep-seated tumor is limited due to three main reasons: Limited light penetration depth, low oxygen concentration in the hypoxic core, and poor PS accumulation inside a tumor. Thus, PDT treatments are only approved for superficial and thin tumors. With the advancement of nanotechnology, PDT to treat deep-seated or thick tumors is becoming a reachable goal. In this review, we provide an update on the strategies for improving PDT with nanomedicine using different sophisticated-design nanoparticles, including two-photon excitation, X-ray activation, targeting tumor cells with surface modification, alteration of tumor cell metabolism pathways, release of therapeutic gases, improvement of tumor hypoxia, and stimulation of host immunity. We focus on the difficult-to-treat pancreatic cancer as a model to demonstrate the influence of advanced nanomedicine in PDT. A bright future of PDT application in the treatment of deep-seated tumors is expected.

Untargeted metabolomics for Achilles heel of engineered nanomaterials' risk assessment

Owing to the superlative properties, engineered nanomaterials (ENM) are being used in food, cosmetics, medicine, and electronics. Therefore, exogenous ENM can be housed into humans through a multitude of exposure routes, leading to compromise of the biomolecules' functionalities through structural deformations, and even at the metabolic level. Consequently, it is of great importance to understand the perturbations introduced at the metabolic level for the timely risk assessment (RA) of ENM. Current technological advancements in metabolomics empower us to visualize the metabolic dysregulations in biological cells, tissues, and living objects, instigated by the ENM. Given the fact, we propose multitiered untargeted metabolomics for the risk assessment of ENM. We propose largely validated experimental design principles that enable the well-organized and authentic identification of metabolic dysregulation connected with a newly engineered nanomaterial. Our scheme could participate in the enhanced transparency of the RA course of rapidly emerging ENM.

Energy-converting biomaterials for cancer therapy: Category, efficiency, and biosafety

Energy-converting biomaterials (ECBs)-mediated cancer-therapeutic modalities have been extensively explored, which have achieved remarkable benefits to overwhelm the obstacles of traditional cancer-treatment modalities. Energy-driven cancer-therapeutic modalities feature their distinctive merits, including noninvasiveness, low mammalian toxicity, adequate therapeutic outcome, and optimistical synergistic therapeutics. In this advanced review, the prevailing mainstream ECBs can be divided into two sections: Reactive oxygen species (ROS)-associated energy-converting biomaterials (ROS-ECBs) and hyperthermia-related energy-converting biomaterials (H-ECBs). On the one hand, ROS-ECBs can transfer exogenous or endogenous energy (such as light, radiation, ultrasound, or chemical) to generate and release highly toxic ROS for inducing tumor cell apoptosis/necrosis, including photo-driven ROS-ECBs for photodynamic therapy, radiation-driven ROS-ECBs for radiotherapy, ultrasound-driven ROS-ECBs for sonodynamic therapy, and chemical-driven ROS-ECBs for chemodynamic therapy. On the other hand, H-ECBs could translate the external energy (such as light and magnetic) into heat for killing tumor cells, including photo-converted H-ECBs for photothermal therapy and magnetic-converted H-ECBs for magnetic hyperthermia therapy. Additionally, the biosafety issues of ECBs are expounded preliminarily, guaranteeing the ever-stringent requirements of clinical translation. Finally, we discussed the prospects and facing challenges for constructing the new-generation ECBs for establishing intriguing energy-driven cancer-therapeutic modalities. This article is categorized under: Nanotechnology Approaches to Biology >Nanoscale Systems in Biology.

Dual-Stimuli-Responsive Multifunctional Gd2Hf2O7 Nanoparticles for MRI-Guided Combined Chemo-/Photothermal-/Radiotherapy of Resistant Tumors

The design and synthesis of a novel generation of a nanoscaled platform with imaging-guided therapy remain a real challenge. It can not only improve the imaging sensitivity of tumor tissues for guiding all kinds of treatments but also reduce the harm for healthy tissues. Here, polydopamine (PDA), polyethylene glycol (PEG), and c(RGDyK) peptide (RGD)-modified and cisplatin-loaded Gd₂Hf₂O₇ nanoparticles (Gd₂Hf₂O₇@PDA@PEG-Pt-RGD NPs) are designed for magnetic resonance imaging (MRI)-guided combined chemo-/photothermal-/radiotherapy of resistant tumors. The as-prepared NPs display high relaxivity (r₁ = 38.28 mM^-1 s^-1) as an MRI contrast agent because of their ultrasmall size and surface modification with polyacrylic acid and PDA. Gd₂Hf₂O₇@PDA@PEG-Pt-RGD NPs exhibit pH and NIR dual-stimuli responsiveness for cisplatin release. Based on competent NIR absorption and high X-ray attenuation efficiency, Gd₂Hf₂O₇@PDA@PEG-Pt-RGD NPs show potential photothermal effect by exposing to an 808 nm NIR laser and significantly improve the generation of reactive oxygen species after X-ray radiation. Combined chemo-/photothermal-/radiotherapy can effectively treat the resistant A549R cells, providing the enhanced therapeutic efficiency to cancer tissues and the reduced side effect to healthy tissues. Furthermore, Gd₂Hf₂O₇@PDA@PEG-Pt-RGD NPs present no obvious toxicity during the treatment, which demonstrates the potential as an efficient MRI-guided combined chemo-/photothermal-/radiotherapy nanoplatform for drug-resistant tumors.

Versatile Nanoplatforms with enhanced Photodynamic Therapy: Designs and Applications

As an emerging antitumor strategy, photodynamic therapy (PDT) has attracted intensive attention for the treatment of various malignant tumors owing to its noninvasive nature and high spatial selectivity in recent years. However, the therapeutic effect is unsatisfactory on some occasions due to the presence of some unfavorable factors including nonspecific accumulation of PS towards malignant tissues, the lack of endogenous oxygen in tumors, as well as the limited light penetration depth, further hampering practical application. To circumvent these limitations and improve real utilization efficiency, various enhanced strategies have been developed and explored during the past years. In this review, we give an overview of the state-of-the-art advances progress on versatile nanoplatforms for enhanced PDT considering the enhancement from targeting or responsive, chemical and physical effect. Specifically, these effects mainly include organelle-targeting function, tumor microenvironment responsive release photosensitizers (PS), self-sufficient O2 (affinity oxygen and generating oxygen), photocatalytic water splitting, X-rays light stimulate, surface plasmon resonance enhancement, and the improvement by resonance energy transfer. When utilizing these strategies to improve the therapeutic effect, the advantages and limitations are addressed. Finally, the challenges and prospective will be discussed and demonstrated for the future development of advanced PDT with enhanced efficacy.

Nanocomposites for X-Ray Photodynamic Therapy

Photodynamic therapy (PDT) has long been known as an effective method for treating surface cancer tissues. Although this technique is widely used in modern medicine, some novel approaches for deep lying tumors have to be developed. Recently, deeper penetration of X-rays into tissues has been implemented, which is now known as X-ray photodynamic therapy (XPDT). The two methods differ in the photon energy used, thus requiring the use of different types of scintillating nanoparticles. These nanoparticles are known to convert the incident energy into the activation energy of a photosensitizer, which leads to the generation of reactive oxygen species. Since not all photosensitizers are found to be suitable for the currently used scintillating nanoparticles, it is necessary to find the most effective biocompatible combination of these two agents. The most successful combinations of nanoparticles for XPDT are presented. Nanomaterials such as metal-organic frameworks having properties of photosensitizers and scintillation nanoparticles are reported to have been used as XPDT agents. The role of metal-organic frameworks for applying XPDT as well as the mechanism underlying the generation of reactive oxygen species are discussed.

Multifunctional Nanoparticles for Multimodal Imaging-Guided Low-Intensity Focused Ultrasound/Immunosynergistic Retinoblastoma Therapy

Retinoblastoma (RB) is prone to delayed diagnosis or treatment and has an increased likelihood of metastasizing. Thus, it is crucial to perform an effective imaging examination and provide optimal treatment of RB to prevent metastasis. Nanoparticles that support diagnostic imaging and targeted therapy are expected to noninvasively integrate tumor diagnosis and treatment. Herein, we report a multifunctional nanoparticle for multimodal imaging-guided low-intensity focused ultrasound (LIFU)/immunosynergistic RB therapy. Magnetic hollow mesoporous gold nanocages (AuNCs) conjugated with Fe₃O₄ nanoparticles (AuNCs-Fe₃O₄) were prepared to encapsulate muramyl dipeptide (MDP) and perfluoropentane (PFP). The multimodal imaging capabilities, antitumor effects, and dendritic cell (DC) activation capacity of these nanoparticles combined with LIFU were explored in vitro and in vivo. The biosafety of AuNCs-Fe₃O₄/MDP/PFP was also evaluated systematically. The multifunctional magnetic nanoparticles enhanced photoacoustic (PA), ultrasound (US), and magnetic resonance (MR) imaging in vivo and in vitro, which was helpful for diagnosis and efficacy evaluation. Upon accumulation in tumors via a magnetic field, the nanoparticles underwent phase transition under LIFU irradiation and MDP was released. A combined effect of AuNCs-Fe₃O₄/MDP/PFP and LIFU was recorded and verified. AuNCs-Fe₃O₄/MDP/PFP enhanced the therapeutic effect of LIFU and led to direct apoptosis/necrosis of tumors, while MDP promoted DC maturation and activation and activated the ability of DCs to recognize and clear tumor cells. By enhancing PA/US/MR imaging and inhibiting tumor growth, the multifunctional AuNC-Fe₃O₄/MDP/PFP nanoparticles show great potential for multimodal imaging-guided LIFU/immunosynergistic therapy of RB. The proposed nanoplatform facilitates cancer theranostics with high biosafety.