Ultrasmall BiOI Quantum Dots with Efficient Renal Clearance for Enhanced Radiotherapy of Cancer

Semiconductor-mediated radiosensitizers: progress, challenges and perspectives

Radiotherapy has become one indispensable treatment strategy for treating malignant tumors. However, the therapeutic effect of radiotherapy is limited due to the low sensitivity and large side effects of existing radiosensitizers. The rapid development of nanotechnology has created opportunities for various novel kinds of radiosensitizers with excellent radiosensitivity to sprout recently. In particular, due to the ease of modification and potential utilization capacity for a multifunctional radiotherapy platform, semiconductor radiosensitizers have attracted more and more attention. Recently, many novel semiconductor based radiosensitizers have been reported, which provides new ideas for the improvement of radiotherapy efficacy. To make further breakthroughs in semiconductor radiosensitizers, a systematic review is urgently needed and is herein provided. This review first elaborates on the principle of semiconductor induced radiosensitization, and then focuses on strategies such as doping and constructing heterojunctions to enhance the radiosensitivity of semiconductors. Next, it introduces in detail the principle and progress of different types of semiconductor radiosensitizers. Finally, challenges and perspectives of semiconductor radiosensitizers are proposed and discussed, offering guidance for future commercial applications of semiconductor radiosensitizers.

Enhancing Chordoma Radiotherapy: Ta@PVP Nanoparticles as Potent Radiosensitizers

Surgical resection and high-dose radiotherapy constitute the standard therapeutic approaches for chordoma. However, the efficacy of radiotherapy is often compromised by the tumor microenvironment's hypoxic conditions, which confer radiation resistance, and by the potential damage to adjacent spinal cord and neural structures from elevated radiation doses. To address these challenges, we employed high biocompatible poly(vinylpyrrolidone)-modified tantalum nanoparticles (Ta@PVP NPs) as a potent radiosensitizer to augment the radiotherapy sensitivity of chordoma. Upon exposure to X-ray irradiation, Ta@PVP NPs demonstrated the capability to efficiently deposit X-ray radiation energy within the tumor microenvironment, subsequently generating reactive oxygen species (ROS) that induce oxidative stress in the tumor. Both in vitro and in vivo experiments revealed that Ta@PVP NPs significantly enhanced the cytotoxic effects of X-ray, thereby markedly inhibiting the proliferation of chordoma cells and impeding tumor growth. This study explored the radiosensitization potential of Ta@PVP NPs in the context of chordoma, highlighting the application of radiosensitizers as a promising strategy to augment the efficacy of chordoma radiotherapy.

Oxygen-defect bismuth oxychloride nanosheets for ultrasonic cavitation effect enhanced sonodynamic and second near-infrared photo-induced therapy of breast cancer

Sonodynamic therapy (SDT) relies heavily on the presence of oxygen to induce cell death. Its effectiveness is thus diminished in the hypoxic regions of tumor tissue. To address this issue, the exploration of ultrasound-based synergistic treatment modalities has become a significant research focus. Here, we report an ultrasonic cavitation effect enhanced sonodynamic and 1208 nm photo-induced cancer treatment strategy based on thermoelectric/piezoelectric oxygen-defect bismuth oxychloride nanosheets (BNs) to realize the high-performance eradication of tumors. Upon ultrasonic irradiation, the local high temperature and high pressure generated by the ultrasonic cavitation effect combined with the thermoelectric and piezoelectric effects of BNs create a built-in electric field. This facilitates the separation of carriers, increasing their mobility and extending their lifetimes, thereby greatly improving the effectiveness of SDT and NIR-Ⅱ phototherapy on hypoxia. The Tween-20 modified BNs (TBNs) demonstrate ∼88.6 % elimination rate against deep-seated tumor cells under hypoxic conditions. In vivo experiments confirm the excellent antitumor efficacy of TBNs, achieving complete tumor elimination within 10 days with no recurrences. Furthermore, due to the high X-ray attenuation of Bi and excellent NIR-Ⅱ absorption, TBNs enable precise cancer diagnosis through photoacoustic (PA) imaging and computed tomography (CT).

Bismuth Chelate-Mediated Digital Subtraction Angiography

Digital subtraction angiography (DSA) is considered the "gold standard" for the diagnosis of vascular diseases. However, the contrast agents used in DSA are limited to iodine (I)-based small molecules, which are unsuitable for patients with contraindications. Here, iodine-free DSA utilizing a bismuth (Bi) chelate, Bi-DTPA Dimeglumine, is proposed for vascular visualization for the first time. Bi-DTPA Dimeglumine possesses a simple synthesis process without the need for purification, large-scale production ability (over 200 g in the lab), superior X-ray imaging capability, renal clearance capacity, and good biocompatibility. Bi-DTPA-enhanced DSA can clearly display the arteries of the rabbit's head and lower limbs, with a minimum vascular resolution of 0.5 mm. The displayed integrity of terminal vessels by Bi-DTPA-enhanced DSA is superior to that of iopromide-enhanced DSA. In a rabbit model of thrombotic disease, Bi-DTPA Dimeglumine-enhanced DSA enables the detection of embolism and subsequent reevaluation of vascular conditions after recanalization therapy. This proposed iodine-free DSA provides a promising and universal approach for diagnosing vascular diseases.

Self-Chemiluminescence-Triggered Ir(III) Complex Photosensitizer for Photodynamic Therapy against Hypoxic Tumor

The limited optical penetration depth and hypoxic tumor microenvironment (TME) are key factors that hinder the practical applications of conventional photodynamic therapy (PDT). To fundamentally address these issues, self-luminescent photosensitizers (PSs) can achieve efficient PDT. Herein, a self-chemiluminescence (CL)-triggered Ir complex PS, namely, IrL2, with low-O2-dependence type I photochemical processes is reported for efficient PDT. The rational design achieves efficient chemiluminescence resonance energy transfer (CRET) from covalently bonded luminol units to the Ir complex in IrL2 under the catalysis of H2O2 and hemoglobin (Hb) to generate O2•- and 1O2. Liposome IrL2H nanoparticles (NPs) are constructed by loading IrL2 and Hb. The intracellular H2O2 and loaded Hb catalyze the luminol part of IrL2H, and the Ir2 part is then excited to produce types I and II reactive oxygen species (ROS) through CRET, inducing cell death, even under hypoxic conditions, and promoting cell apoptosis. IrL2H is used for tumor imaging and inhibits tumor growth in 4T1-bearing mouse models through intratumoral injection without external light sources. This work provides new designs for transition metal complex PSs that conquer the limitations of external light sources and the hypoxic TME in PDT.

Ultra-small Janus nanoparticle-induced activation of ferroptosis for synergistic tumor immunotherapy

Ferroptosis induced by lipid peroxide (LPO) accumulation is an effective cell death pathway for cancer therapy. However, how to effectively induce ferroptosis at tumor sites and improve its therapeutic effectiveness remains challenging. Here, MnFe2O4@NaGdF4@NLG919@HA (MGNH) nanocomplex with tumor-specific targeting and TME response is constructed to overcome immunosuppressive tumor microenvironment (TME) to potentiate the curative effect of ferroptosis by coupling the immune checkpoint indoleamine 2,3-dioxygenase (IDO) inhibitor, NLG919, and hyaluronic acid (HA) to novel ultra-small MnFe2O4@NaGdF4 (MG) nanoparticles with a Janus structure. Firstly, tumor site-precise delivery of MG and NLG919 is achieved with HA targeting. Secondly, MG acts as a magnetic resonance imaging contrast agent, which not only has a good photothermal effect to realize tumor photothermal therapy, but also depletes glutathione and catalyzes the production of reactive oxygen species from endogenous H2O2, which effectively promotes the accumulation of LPO and inhibits the expression of glutathione peroxidase 4, achieving enhanced ferroptosis. Thirdly, NLG919 inhibits the differentiation of Tregs by blocking the tryptophan/kynurenine immune escape pathway, thereby reversing immunosuppressive TME together with the Mn2+-activated cGAS-STING pathway. This work contributes new perspectives for the development of novel ultra-small Janus nanoparticles to reshape immunosuppressive TME and ferroptosis activation. STATEMENT OF SIGNIFICANCE: The Janus structured MnFe2O4@NaGdF4@NLG919@HA (MGNH) nanocomplex was synthesized, which can realize the precise delivery of T1/T2 contrast agents MnFe2O4@NaGdF4 (MG) and NLG919 at the tumor site under the ultra-small Janus structural characteristics and targeted molecule HA. The production of ROS, consumption of GSH, and photothermal properties of MGNH make it possible for CDT/PTT activated ferroptosis, and synergistically disrupt and reprogram tumor growth and immunosuppressive tumor microenvironment with NLG919 and Mn2+-mediated activation of cGAS-STING pathway, achieving CDT/PTT/immunotherapy activated by ferroptosis. Meanwhile, ultra-small structural properties of MGNH facilitate subsequent metabolic clearance by the body, allowing for the minimization of potential biotoxicity associated with its prolonged retention.

High-Z elements dominated bismuth-based heterojunction nano-semiconductor for radiotherapy-enhanced sonodynamic breast cancer therapy

Ultrasound and X-rays possess remarkable tissue penetration capabilities, making them promising candidates for cancer therapy. Sonodynamic therapy, which utilizes ultrasound excitation, offers a safer alternative to radiotherapy and can be combined with X-rays to mitigate the adverse effects on normal tissues. In this study, we developed a bismuth-based heterostructure semiconductor (BFIP) to enhance the efficacy of radiotherapy and sonodynamic therapy in treating breast cancer. The semiconductor is fabricated through a two-step process involving the synthesis of porous spherical bismuth fluoride and partially reduced to bismuth oxyiodide. Then, followed by surface modification with amphiphilic polyethylene glycol, BFIP is fabricated. Incorporating heavy atoms in the BFIP enhances radiosensitivity. The BFIP exhibits superior carrier separation efficiency compared to bismuth fluoride, generating a substantial quantity of reactive oxygen species upon ultrasound stimulation. Moreover, the BFIP effectively depletes glutathione through coordination and hole-mediated oxidation pathways, disrupting the tumor microenvironment and inducing oxidative stress. Encouraging results are acquired in both in vitro cell and in vivo tumor models. Our study provides a de-risking strategy by utilizing ultrasound as a partial substitute for X-rays in treating deep-seated tumors, offering a viable research direction for constructing a unified nanoplatform.

Thymosin beta 10 loaded ZIF-8/sericin hydrogel promoting angiogenesis and osteogenesis for bone regeneration

Angiogenesis is pivotal for osteogenesis during bone regeneration. A hydrogel that promotes both angiogenesis and osteogenesis is essential in bone tissue engineering. However, creating scaffolds with the ideal balance of biodegradability, osteogenic, and angiogenic properties poses a challenge. Thymosin beta 10 (TMSB10), known for its dual role in angiogenesis and osteogenesis differentiation, faces limitations due to protein activity preservation. To tackle this issue, ZIF-8 was engineered as a carrier for TMSB10 (TMSB10@ZIF-8), and subsequently integrated into the self-assembled sericin hydrogel. The efficacy of the composite hydrogel in bone repair was assessed using a rat cranial defect model. Characterization of the nanocomposites confirmed the successful synthesis of TMSB10@ZIF-8, with a TMSB10 encapsulation efficiency of 88.21 %. The sustained release of TMSB10 from TMSB10@ZIF-8 has significantly enhanced tube formation in human umbilical vein endothelial cells (HUVECs) in vitro and promoted angiogenesis in the chicken chorioallantoic membrane (CAM) model in vivo. It has markedly improved the osteogenic differentiation ability of MC 3 T3-E1 cells in vitro. 8 weeks post-implantation, the TMSB10@ZIF-8/ Sericin hydrogel group exhibited significant bone healing (86.77 ± 8.91 %), outperforming controls. Thus, the TMSB10@ZIF-8/Sericin hydrogel, leveraging ZIF-8 for TMSB10 delivery, emerges as a promising bone regeneration scaffold with substantial clinical application potential.

Nanomaterials-Induced Redox Imbalance: Challenged and Opportunities for Nanomaterials in Cancer Therapy

Cancer cells typically display redox imbalance compared with normal cells due to increased metabolic rate, accumulated mitochondrial dysfunction, elevated cell signaling, and accelerated peroxisomal activities. This redox imbalance may regulate gene expression, alter protein stability, and modulate existing cellular programs, resulting in inefficient treatment modalities. Therapeutic strategies targeting intra- or extracellular redox states of cancer cells at varying state of progression may trigger programmed cell death if exceeded a certain threshold, enabling therapeutic selectivity and overcoming cancer resistance to radiotherapy and chemotherapy. Nanotechnology provides new opportunities for modulating redox state in cancer cells due to their excellent designability and high reactivity. Various nanomaterials are widely researched to enhance highly reactive substances (free radicals) production, disrupt the endogenous antioxidant defense systems, or both. Here, the physiological features of redox imbalance in cancer cells are described and the challenges in modulating redox state in cancer cells are illustrated. Then, nanomaterials that regulate redox imbalance are classified and elaborated upon based on their ability to target redox regulations. Finally, the future perspectives in this field are proposed. It is hoped this review provides guidance for the design of nanomaterials-based approaches involving modulating intra- or extracellular redox states for cancer therapy, especially for cancers resistant to radiotherapy or chemotherapy, etc.

Size Switchable Self-Assembled Iron Oxide Aggregations Loaded with Doxorubicin for Deep Penetration and Enhanced Chemotherapy of Cancer

Iron oxide nanoparticles (Fe3O4 NPs) have been reported to be a promising agent for cancer therapy due to their outstanding ability in catalyzing the Fenton reaction and causing peroxidation. Generally, particles with size of hundreds of nanometers exhibit enhanced accumulation in tumor due to the enhanced permeation and retention effect. However, the large size hinders penetration within the dense collagen matrix. Here, we propose a multistage system to realize pH-responsive size switch for efficient drug delivery. In this system, ultrasmall Fe3O4 (∼4 nm) NPs are simultaneously modified with hydrophilic mPEG and hydrophobic N,N-dibutylethylenediamine (DBE) to form pH-responsive self-assembled iron oxide aggregations (SIOA). In the acidic tumor microenvironment, the protonation of DBE makes it transit from the hydrophobic to hydrophilic state, causing the disassembly of the SIOA and the release of loaded doxorubicin. The multistage Fe3O4 NPs demonstrate enhanced accumulation and efficient diffusion within the tumor, holding a promise for drug delivery and cancer therapy.

Inorganic Nanoparticles as Radiosensitizers for Cancer Treatment

Nanotechnology has expanded what can be achieved in our approach to cancer treatment. The ability to produce and engineer functional nanoparticle formulations to elicit higher incidences of tumor cell radiolysis has resulted in substantial improvements in cancer cell eradication while also permitting multi-modal biomedical functionalities. These radiosensitive nanomaterials utilize material characteristics, such as radio-blocking/absorbing high-Z atomic number elements, to mediate localized effects from therapeutic irradiation. These materials thereby allow subsequent scattered or emitted radiation to produce direct (e.g., damage to genetic materials) or indirect (e.g., protein oxidation, reactive oxygen species formation) damage to tumor cells. Using nanomaterials that activate under certain physiologic conditions, such as the tumor microenvironment, can selectively target tumor cells. These characteristics, combined with biological interactions that can target the tumor environment, allow for localized radio-sensitization while mitigating damage to healthy cells. This review explores the various nanomaterial formulations utilized in cancer radiosensitivity research. Emphasis on inorganic nanomaterials showcases the specific material characteristics that enable higher incidences of radiation while ensuring localized cancer targeting based on tumor microenvironment activation. The aim of this review is to guide future research in cancer radiosensitization using nanomaterial formulations and to detail common approaches to its treatment, as well as their relations to commonly implemented radiotherapy techniques.

Tantalum Nitride-Based Theranostic Agent for Photoacoustic Imaging-Guided Photothermal Therapy in the Second NIR Window

Metal nitrides show excellent photothermal stability and conversion properties, which have the potential for photothermal therapy (PTT) for cancer. Photoacoustic imaging (PAI) is a new non-invasive and non-ionizing biomedical imaging method that can provide real-time guidance for precise cancer treatment. In this work, we develop polyvinylpyrrolidone-functionalized tantalum nitride nanoparticles (defined as TaN-PVP NPs) for PAI-guided PTT of cancer in the second near-infrared (NIR-II) window. The TaN-PVP NPs are obtained by ultrasonic crushing of massive tantalum nitride and further modification by PVP to obtain good dispersion in water. Due to their good absorbance in the NIR-II window, TaN-PVP NPs with good biocompatibility have obvious photothermal conversion performance, realizing efficient tumor elimination by PTT in the NIR-II window. Meanwhile, the excellent PAI and photothermal imaging (PTI) capabilities of TaN-PVP NPs are able to provide monitoring and guidance for the treatment process. These results indicate that TaN-PVP NPs are qualified for cancer photothermal theranostics.

A review of bismuth-based nanoparticles and their applications in radiosensitising and dose enhancement for cancer radiation therapy

About 50% of cancer patients receive radiation therapy. Despite the therapeutic benefits of this method, the toxicity of radiation in the normal tissues is unavoidable To improve the quality of radiation therapy, in addition to other methods such as IMRT, IGRT, and high radiation dose, nanoparticles have shown excellent potential when ionising radiation is applied to the target volume. Recently, bismuth-based nanoparticles (BiNPs) have become particularly popular in radiation therapy due to their high atomic numbers (Z), high X-ray attenuation coefficient, low toxicity, and low cost. Moreover, it is easy to synthesise in a variety of sizes and shapes. This study aimed to review the effects of the bismuth-based NP and its combination with other compounds, and their potential synergies in radiotherapy, discussed based on their physical, chemical, and biological interactions. Targeted and non-targeted bismuth-based NPs used in radiotherapy as radiosensitizers and dose enhancement effects are described. The results reported in the literature were categorised into various groups. Also, this review has highlighted the importance of bismuth-based NPs in different forms of cancer treatment to find the highest efficiency for applying them as a suitable candidate for various cancer therapy and future clinical applications.

Tracking of Intestinal Probiotics In Vivo by NIR-IIb Fluorescence Imaging

The ability to accurately characterize microorganism distribution in the intestinal tract is helpful for understanding intrinsic mechanisms. Within the intestine, traditional optical probes used for microorganism labeling commonly suffer from a low imaging penetration depth and poor resolution. We report a novel observation tool useful for microbial research by labeling near-infrared-IIb (NIR-IIb, 1500-1700 nm) lanthanide nanomaterials NaGdF4:Yb3+,Er3+@NaGdF4,Nd3+ (Er@Nd NPs) onto the surface of Lactobacillus bulgaricus (L. bulgaricus) via EDC-NHS chemistry. We monitor microorganisms in tissue by two-photon excitation (TPE) microscopy and in vivo with NIR-IIb imaging. This dual-technique approach offers great potential for determining the distribution of transplanted bacteria in the intestinal tract with a higher spatiotemporal resolution.

Tantalum-Zirconium Co-Doped Metal-Organic Frameworks Sequentially Sensitize Radio-Radiodynamic-Immunotherapy for Metastatic Osteosarcoma

Due to radiation resistance and the immunosuppressive microenvironment of metastatic osteosarcoma, novel radiosensitizers that can sensitize radiotherapy (RT) and antitumor immunity synchronously urgently needed. Here, the authors developed a nanoscale metal-organic framework (MOF, named TZM) by co-doping high-atomic elements Ta and Zr as metal nodes and porphyrinic molecules (tetrakis(4-carboxyphenyl)porphyrin (TCPP)) as a photosensitizing ligand. Given the 3D arrays of ultra-small heavy metals, porous TZM serves as an efficient attenuator absorbing X-ray energy and sensitizing hydroxyl radical generation for RT. Ta-Zr co-doping narrowed the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap and exhibited close energy levels between the singlet and triplet photoexcited states, facilitating TZM transfer energy to the photosensitizer TCPP to sensitize singlet oxygen (1 O2 ) generation for radiodynamic therapy (RDT). The sensitized RT-RDT effects of TZM elicit a robust antitumor immune response by inducing immunogenic cell death, promoting dendritic cell maturation, and upregulating programmed cell death protein 1 (PD-L1) expression via the cGAS-STING pathway. Furthermore, a combination of TZM, X-ray, and anti-PD-L1 treatments amplify antitumor immunotherapy and efficiently arrest osteosarcoma growth and metastasis. These results indicate that TZM is a promising radiosensitizer for the synergistic RT and immunotherapy of metastatic osteosarcoma.

An iodide-containing covalent organic framework for enhanced radiotherapy

Metal-free radiosensitizers, particularly iodine, have shown promise in enhancing radiotherapy due to their suitable X-ray absorption capacities and negligible biotoxicities. However, conventional iodine compounds have very short circulating half-lives and are not retained in tumors very well, which significantly limits their applications. Covalent organic frameworks (COFs) are highly biocompatible crystalline organic porous materials that are flourishing in nanomedicine but have not been developed for radiosensitization applications. Herein, we report the room-temperature synthesis of an iodide-containing cationic COF by the three-component one-pot reaction. The obtained TDI-COF can be a tumor radiosensitizer for enhanced radiotherapy by radiation-induced DNA double-strand breakage and lipid peroxidation and inhibits colorectal tumor growth by inducing ferroptosis. Our results highlight the excellent potential of metal-free COFs as radiotherapy sensitizers.

Calcination-controlled performance optimization of iron-vanadium bimetallic oxide nanoparticles for synergistic tumor therapy

Calcination has been widely demonstrated as a favorable protocol for producing various inorganic nanomaterials for tumor therapy. However, little attention has been paid to its effect on the biotherapeutic efficacy of inorganic nanomaterials. Herein, we compare the effects of different calcination atmospheres on the therapeutic efficacy of Fe-V-O (FVO) nanomaterials. We find that compared with FVO nanomaterials synthesized by calcination in air, those prepared by argon calcination have a lower metallic valence state and a higher near-infrared light absorption capacity, hence resulting in significantly better biosafety and higher chemodynamic therapy (CDT)/photothermal therapy (PTT) efficacy. This study demonstrates that the therapeutic efficacy of inorganic nanomaterials can be optimized by employing different thermal treatment atmospheres, which provides new insights into the development of efficient anti-tumor agents.

Oxygen-generating biocatalytic nanomaterials for tumor hypoxia relief in cancer radiotherapy

Radiotherapy (RT), the most commonly used treatment method in clinics, shows unique advantages such as strong penetration, high energy intensity, and low systemic side effects. However, in vivo tumor hypoxia seriously hinders the therapeutic effect of RT. Hypoxia is a common characteristic of locally advanced solid tumor microenvironments, which leads to the proliferation, invasion and metastasis of tumor cells. In addition, oxygen consumption during RT will further aggravate tumor hypoxia, causing a variety of adverse side effects. In recent years, various biocatalytic nanomaterials (BCNs) have been explored to regulate and reverse tumor hypoxia microenvironments during RT. In this review, the most recent efforts toward developing oxygen-generating BCNs in relieving tumor hypoxia in RT are focused upon. The classification, engineering nanocatalytical activity of oxygen-generating BCNs and combined therapy based on these BCNs are systematically introduced and discussed. The challenges and prospects of these oxygen-generating BCNs in RT applications are also summarized.

A Cell-Penetrating Peptide Modified Cu2-xSe/Au Nanohybrid with Enhanced Efficacy for Combined Radio-Photothermal Therapy

Radiotherapy (RT) is one of the main clinical therapeutic strategies against cancer. Currently, multiple radiosensitizers aimed at enhancing X-ray absorption in cancer tissues have been developed, while limitations still exist for their further applications, such as poor cellular uptake, hypoxia-induced radioresistance, and unavoidable damage to adjacent normal body tissues. In order to address these problems, a cell-penetrating TAT peptide (YGRKKRRQRRRC)-modified nanohybrid was constructed by doping high-Z element Au in hollow semiconductor Cu_2-xSe nanoparticles for combined RT and photothermal therapy (PTT) against breast cancer. The obtained Cu_2-xSe nanoparticles possessed excellent radiosensitizing properties based on their particular band structures, and high photothermal conversion efficiency beneficial for tumor ablation and promoting RT efficacy. Further doping high-Z element Au deposited more high-energy radiation for better radiosensitizing performance. Conjugation of TAT peptides outside the constructed Cu_2-xSe/Au nanoparticles facilitated their cellular uptake, thus reducing overdosage-induced side effects. This prepared multifunctional nanohybrid showed powerful suppression effects towards breast cancer, both in vitro and in vivo via integrating enhanced cell penetration and uptake, and combined RT/PTT strategies.

Self-targeting platinum(IV) amphiphilic prodrug nano-assembly as radiosensitizer for synergistic and safe chemoradiotherapy of hepatocellular carcinoma

Chemoradiotherapy is a widely used treatment for patients with malignancies such as hepatocellular carcinoma (HCC). However, it remains challenging to realize safe and synergistic chemotherapy and radiation sensitization. Herein, we design a self-targeting nano-assembly (STNA) based on platinum(IV)-lactose amphiphilic prodrug for synergistic and safe chemoradiotherapy of HCC. The Pt STNA would improve the tumor accumulation due to the targeting ability of lactose to HCC cells. After receptor-mediated endocytosis, Pt STNA would release cisplatin(II) in cancer cells to form DNA-binding, thus inducing DNA damage and cell apoptosis. Meanwhile, the DNA-binding also causes cell cycle arrest in the radiation-sensitive G2/M phase by the up-regulation of phosphorylated checkpoint kinase 1 (p-Chk1) expression. Furthermore, under X-ray irradiation, Pt STNA as radiosensitizer possesses a strong X-ray attenuation ability to deposit more energy, thus elevating the level of reactive oxygen species (ROS) to amplify the cell-killing effect of radiotherapy in the G2/M phase with increased DNA damage. As a result, Pt STNA exhibits significant synergistic therapeutic effects in chemoradiotherapy with no adverse effects in vitro and in vivo. Overall, we present a novel self-targeting nano-assembly strategy based on widely used Pt drugs for synergistic chemotherapy and radiation sensitization of HCC treatment.

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.

Albumin-assembled copper-bismuth bimetallic sulfide bioactive nanosphere as an amplifier of oxidative stress for enhanced radio-chemodynamic combination therapy

The tumor microenvironment with overexpressed hydrogen peroxide (H2O2) and reinforced antioxidative system (glutathione, GSH) becomes a double-edged sword for the accessibility of nano-therapy. Since reactive oxygen species (ROS) are easily quenched by the developed antioxidative network, ROS-based treatments such as chemodynamic therapy (CDT) and radiotherapy (RT) for killing cancer cells are severely attenuated. To overcome such limitations, a bioactive nanosphere system is developed to regulate intracellular oxidative stress for enhanced radio-chemodynamic combination therapy by using bovine serum albumin (BSA) based bioactive nanospheres that are BSA assembled with in situ generated copper-bismuth sulfide nanodots and diallyl trisulfide (DATS). The copper-bismuth sulfide nanodots react with H2O2 to produce •OH and release Cu2+. Then, the Cu2+ further depletes GSH to generate Cu+ for more •OH generation in the way of Fenton-like reaction. Such a cascade reaction can initiate •OH generation and GSH consumption to realize CDT. The elevation of ROS triggered by the DATS from BBCD nanospheres further augments the breaking of redox balance for the increased oxidative stress in 4T1 cells. With the sensitization of increased oxidative stress and high Z element Bi, an enhanced radio-chemodynamic combination therapy is achieved. The current work provides an enhanced radio-chemodynamic combination treatment for the majority of solid tumors by using the co-assembled bioactive nanospheres as an amplifier of oxidative stress.

Biocompatible Tantalum Nanoparticles as Radiosensitizers for Enhancing Therapy Efficacy in Primary Tumor and Metastatic Sentinel Lymph Nodes

Metastasis of breast carcinoma is commonly realized through lymphatic circulation, which seriously threatens the lives of breast cancer patients. Therefore, efficient therapy for both primary tumor and metastatic sentinel lymph nodes (SLNs) is highly desired to inhibit cancer growth and metastasis. During breast cancer treatment, radiotherapy (RT) is a common clinical method. However, the efficacy of RT is decreased by the radioresistance to a hypoxic microenvironment and inevitable side effects for healthy issues at high radiation doses. Considering the above-mentioned, we provide high biocompatible poly(vinylpyrrolidone) coated Ta nanoparticles (Ta@PVP NPs) for photothermal therapy (PTT) assisted RT for primary tumor and metastatic SLNs. On the one hand, for primary tumor treatment, Ta@PVP NPs with a high X-ray mass attenuation coefficient (4.30 cm²/kg at 100 keV) can deposit high radiation doses within tumors. On the other hand, for metastatic SLNs treatment, the effective delivery of Ta@PVP NPs from the primary tumor into SLNs is monitored by computed tomography and photoacoustic imaging, which greatly benefit the prognosis and treatment for metastatic SLNs. Moreover, Ta@PVP NPs-mediated PTT could enhance the RT effect, and immunogenic cell death caused by RT/PTT could induce an immune response to improve the therapeutic effect of metastatic SLNs. This study not only explores the potential of Ta@PVP NPs as effective radiosensitizers and photothermal agents for combined RT and PTT but also offers an efficient strategy to cure both primary tumor and metastatic SLNs in breast carcinoma.

PVP-Modified Multifunctional Bi2WO6 Nanosheets for Enhanced CT Imaging and Cancer Radiotherapy

Malignant tumors are one of the main causes of human death. The clinical treatment of malignant tumors is usually surgery, chemotherapy, radiotherapy, and so forth. Radiotherapy, as a traditional and effective treatment method for cancer, is widely used in clinical practice, but the radiation resistance of tumor cells and the toxic side effects to normal cells are still the Achilles heel of radiotherapy. Multifunctional inorganic high-atom nanomaterials are expected to enhance the effect of tumor radiotherapy. Tungsten and bismuth, which contain elements with high atomic coefficients, have strong X-ray energy attenuation capability. We synthesized Bi₂WO₆ nanosheets (NSs) using a hydrothermal synthesis method and modified polyvinylpyrrolidone (PVP) on their surface to make them more stable. PVP-Bi₂WO₆ NSs have a variety of effects after absorbing X-rays (such as the photoelectric effect and Compton effect) and release a variety of particles such as photoelectrons, Compton electrons, auger electrons, and so forth, which can react with organic molecules or water in cells, generate a large number of free radicals, and promote cell apoptosis, thereby improving the effect of radiotherapy. We show through γ-H2AX and DCFH-DA probe analysis experiments that PVP-Bi₂WO₆ NSs can effectively increase cell DNA damage and reactive oxygen species formation under X-ray irradiation. Clone formation analysis showed that PVP-Bi₂WO₆ NSs can effectively suppress cell colony formation under X-ray irradiation. These versatile functions endow PVP-Bi₂WO₆ NSs with enhanced radiotherapy efficacy in animal models. In addition, PVP-Bi₂WO₆ NSs can also be used as contrast agents for X-ray computed tomography (CT) imaging with obvious effects. Therefore, PVP-Bi₂WO₆ NSs can be used as CT imaging contrast agents and tumor radiotherapy sensitizers and have potential medical applications.

Spontaneous Adsorption and Efficient Photodegradation of Indigo Carmine under Visible Light by Bismuth Oxyiodide Nanoparticles Fabricated Entirely at Room Temperature

Bismuth oxyiodide (BiOI) is a targeted material for its relative safety and photocatalytic activity under visible light. In this study, a successful simple and energy-saving route was applied to prepare BiOI through a sonochemical process at room temperature. The characterization of the prepared BiOI was conducted by physical means. The transmission electron microscope (TEM) image showed that the BiOI comprises nanoparticles of about 20 nm. Also, the surface area of the BiOI was found to be 34.03 m2 g−1 with an energy gap of 1.835 eV. The adsorption and photocatalytic capacities of the BiOI were examined for the indigo carmine dye (IC) as a model water-pollutant via the batch experiment methodology. The solution parameters were optimized, including pH, contact time, IC concentration, and temperature. Worth mentioning that an adsorption capacity of 185 mg·g−1 was obtained from 100 mg L−1 IC solution at 25 °C within 60 min as an equilibrium time. In addition, the BiOI showed a high degradation efficiency towards IC under tungsten lamb (80 W), where 93% was removed within 180 min, and the complete degradation was accomplished in 240 min. The fabricated BiOI nanoparticles completely mineralized the IC under artificial visible light, as indicated by the total organic carbon analysis.

Hafnium-Based Metal-Organic Framework Nanoparticles as a Radiosensitizer to Improve Radiotherapy Efficacy in Esophageal Cancer

Radiotherapy is one of the most widely used clinical treatments for tumors, but it faces limitations, such as poor X-ray retention at the tumor site. The use of radiosensitizers containing high Z elements is an effective way to enhance X-ray absorption. Here, we demonstrate a simple one-step method for the synthesis of UiO-66-NH₂(Hf) metal-organic framework nanoparticles for use as radiosensitizers in radiotherapy. The UiO-66-NH₂(Hf) nanoparticles had a diameter of less than 100 nm and were stable in the physiological environment. UiO-66-NH₂(Hf) induced apoptosis by enhancing X-ray absorption, as confirmed by in vitro and in vivo experiments. These characteristics make UiO-66-NH₂(Hf) a promising radiosensitizer for esophageal cancer radiotherapy.

Tumor-Microenvironment-Responsive Biodegradable Nanoagents Based on Lanthanide Nucleotide Self-Assemblies toward Precise Cancer Therapy

Stimuli-responsive nanoagents, which simultaneously satisfy normal tissue clearance and tumor-specific responsive treatment, are highly attractive for precise cancer theranostics. Herein, we develop a unique template-induced self-assembly strategy for the exquisitely controlled synthesis of self-assembled lanthanide (Ln³⁺ ) nucleotide nanoparticles (LNNPs) with amorphous structure and tunable size from sub-5 nm to 105 nm. By virtue of the low-temperature (10 K) and high-resolution spectroscopy, the local site symmetry of Ln³⁺ in LNNPs is unraveled for the first time. The proposed LNNPs are further demonstrated to possess the ability for highly efficient loading and tumor-microenvironment-responsive release of doxorubicin. Particularly, sub-5 nm LNNPs not only exhibit excellent biocompatibility and predominant renal-clearance performance, but also enable efficient tumor retention. These findings reveal the great potential of LNNPs as a new generation of therapeutic platform to overcome the dilemma between efficient therapy and long-term toxicity of nanoagents for future clinical applications.

Recent developments on bismuth oxyhalide-based functional nanomaterials for biomedical applications

Multifunctional bismuth oxyhalide (BiOX, X = F, Cl, Br, and I) nanomaterials have great potential advantages in medical diagnostic and therapeutic applications. Pure BiOX nanomaterials have some limitations such as...

A readily synthesized bismuth oxyiodide/attapulgite for the photodegradation of tetracycline under visible light irradiation

Bismuth oxyiodide and attapulgite have proven to be potential materials for the removal of emerging contaminants in wastewater.

A GdW10@PDA-CAT Sensitizer with High-Z Effect and Self-Supplied Oxygen for Hypoxic-Tumor Radiotherapy

Anticancer treatment is largely affected by the hypoxic tumor microenvironment (TME), which causes the resistance of the tumor to radiotherapy. Combining radiosensitizer compounds and O2 self-enriched moieties is an emerging strategy in hypoxic-tumor treatments. Herein, we engineered GdW10@PDA-CAT (K3Na4H2GdW10O36·2H2O, GdW10, polydopamine, PDA, catalase, CAT) composites as a radiosensitizer for the TME-manipulated enhancement of radiotherapy. In the composites, Gd (Z = 64) and W (Z = 74), as the high Z elements, make X-ray gather in tumor cells, thereby enhancing DNA damage induced by radiation. CAT can convert H2O2 to O2 and H2O to enhance the X-ray effect under hypoxic TME. CAT and PDA modification enhances the biocompatibility of the composites. Our results showed that GdW10@PDA-CAT composites increased the efficiency of radiotherapy in HT29 cells in culture. This polyoxometalates and O2 self-supplement composites provide a promising radiosensitizer for the radiotherapy field.

Selenium Vacancy Engineering Using Bi2Se3 Nanodots for Boosting Highly Efficient Photonic Hyperthermia

Despite bismuth-based energy conversion nanomaterials having attracted extensive attention for nanomedicine, the nanomaterials suffer from major shortcomings including low tumor accumulation, long internal retention time, and undesirable photothermal conversion efficiency (PCE). To combat these challenges, bovine serum albumin and folic acid co-modified Bi2Se3 nanomedicine with rich selenium vacancies (abbreviated as VSe-BS) was fabricated for the second near-infrared (NIR-II) light-triggered photonic hyperthermia. More importantly, selenium vacancies on the crystal planes (0 1 5) and (0 1 11) of VSe-BS with similar formation energies could be distinctively observed via aberration-corrected scanning transmission electron microscopy images. The defect engineering endows VSe-BS with enhanced conductivity, making VSe-BS possess outstanding PCE (54.1%) in the NIR-II biowindow and desirable photoacoustic imaging performance. Tumor ablation studies indicate that VSe-BS possesses satisfactory therapeutic outcomes triggered by NIR-II light. These findings give rise to inspiration for further broadening the biological applications of defect engineering bismuth-based nanomaterials.

Emerging strategies based on nanomaterials for ionizing radiation-optimized drug treatment of cancer

Drug-radiotherapy is a common and effective combinational treatment for cancer. This study aimed to explore the ionizing radiation-optimized drug treatment based on nanomaterials so as to improve the synergistic efficacy of drug-radiotherapy against cancer and limit the adverse effect on healthy organs. In this review, these emerging strategies were divided into four parts. First, the delivery of the drug-loaded nanoparticles was optimized owing to the strengthened passive targeting process, active targeting process, and cell targeting process of nanoparticles after ionizing radiation exposure. Second, nanomaterials were designed to respond to the ionizing radiation, thus leading to the release of the loading drugs controllably. Third, radiation-activated pro-drugs were loaded onto nanoparticles for radiation-triggered drug therapy. In particular, nontoxic nanoparticles with radiosensitization capability and innocuous radio-dynamic contrast agents can be considered as radiation-activated drugs, which were discussed in this review. Fourth, according to the various synergetic mechanisms, radiotherapy could improve the drug response of cancer, obtaining optimized drug-radiotherapy. Finally, relative suggestions were provided to further optimize these aforementioned strategies. Therefore, a novel topic was selected and the emerging strategies in this region were discussed, aiming to stimulate the inspiration for the development of ionizing radiation-optimized drug treatment based on nanomaterials.

Mitochondria-Targeting Enhanced Phototherapy by Intrinsic Characteristics Engineered "One-for-All" Nanoparticles

Mitochondria-targeted synergistic therapy, including photothermal (PTT) and photodynamic therapy (PDT), has aroused wide attention due to the high sensitivity to reactive oxygen species (ROS) and heat shock of mitochondria. However, most of the developed nanosystems for the combinatorial functions require the integration of different components, such as photosensitizers and mitochondria-targeted molecules. Consequently, it indispensably requires sophisticated design and complex synthetic procedures. In this work, a well-designed Bi2S3-based nanoneedle, that localizes to mitochondria and produces extra ROS with inherent photothermal effect, was reported by doping of Fe (denoted as FeBS). The engineered intrinsic characteristics certify the capacity of such "one-for-all" nanosystems without additional molecules. The lipophilicity and surface positive charge are demonstrated as crucial factors for specifical mitochondria targeting. Significantly, Fe doping overcomes the disadvantage of the narrow band gap of Bi2S3 to prevent the fast recombination of electron-hole, hence resulting in the generation of ROS for PDT. The "one-for-all" nanoparticles integrate with mitochondria-targeting and synergistic effect of PDT and PTT, thus exhibit enhanced therapeutic effect and inhibit the growth of tumors observably. This strategy may open a new direction in designing the mitochondria-targeted materials and broadening the properties of inorganic semiconductor materials for satisfactory therapeutic outcomes.

Quantum dots as a theranostic approach in Alzheimer's disease: a systematic review

Aim: Quantum dots (QDs) are nanoparticles that have an emerging application as theranostic agents in several neurodegenerative diseases. The advantage of QDs as nanomedicine is due to their unique optical properties that provide high sensitivity, stability and selectivity at a nanoscale range. Objective: To offer renewed insight into current QD research and elucidate its promising application in Alzheimer's disease (AD) diagnosis and therapy. Methods: A comprehensive literature search was conducted in PubMed and Google Scholar databases that included the following search terms: 'quantum dots', 'blood-brain barrier', 'cytotoxicity', 'toxicity' and 'Alzheimer's disease'; PRISMA guidelines were adhered to. Results: Thirty-four publications were selected to evaluate the ability of QDs to cross the blood-brain barrier, potential toxicity and current AD diagnostic and therapeutic applications. Conclusion: QD's unique optical properties and versatility to conjugate to various biomolecules, while maintaining a nanoscale size, render them a promising theranostic tool in AD.

Inorganic nanomaterials with rapid clearance for biomedical applications

Inorganic nanomaterials that have inherently exceptional physicochemical properties (e.g., catalytic, optical, thermal, electrical, or magnetic performance) that can provide desirable functionality (e.g., drug delivery, diagnostics, imaging, or therapy) have considerable potential for application in the field of biomedicine. However, toxicity can be caused by the long-term, non-specific accumulation of these inorganic nanomaterials in healthy tissues, preventing their large-scale clinical utilization. Over the past several decades, the emergence of biodegradable and clearable inorganic nanomaterials has offered the potential to prevent such long-term toxicity. In addition, a comprehensive understanding of the design of such nanomaterials and their metabolic pathways within the body is essential for enabling the expansion of theranostic applications for various diseases and advancing clinical trials. Thus, it is of critical importance to develop biodegradable and clearable inorganic nanomaterials for biomedical applications. This review systematically summarizes the recent progress of biodegradable and clearable inorganic nanomaterials, particularly for application in cancer theranostics and other disease therapies. The future prospects and opportunities in this rapidly growing biomedical field are also discussed. We believe that this timely and comprehensive review will stimulate and guide additional in-depth studies in the area of inorganic nanomedicine, as rapid in vivo clearance and degradation is likely to be a prerequisite for the future clinical translation of inorganic nanomaterials with unique properties and functionality.

Nanotechnology: Breaking the Current Treatment Limits of Lung Cancer

Lung cancer is one of the most rapidly growing malignancies in terms of morbidity and mortality. Although traditional treatments have been used for more than 50 years, it is still far from solving the problems of postoperative risks and systemic toxicity. Emerging targeting and immunotherapy are developing continuously and are gaining recognition; eventually, they face the inevitable challenge of drug resistance. Nanotechnology has several important effects on lung cancer treatment, owing to its unique properties. Several nanoparticle-based treatments have successfully become cancer treatments. Good biocompatibility with higher specific surface area can carry substantial amounts of lung cancer treatment medications while avoiding medication toxicity; editable and modified characteristics give rise to multifunctional nanomedicines; excellent photoelectric effects make lung cancer a multimodal treatment. This article summarizes the breakthroughs achieved by nanotechnology, targeted therapy, and immunotherapy, reflecting the importance and necessity of nanotechnology in the treatment of lung cancer.

BiVO4/Fe3O4@polydopamine superparticles for tumor multimodal imaging and synergistic therapy

Background

Despite tremendous progress has been achieved in tumor theranostic over the past decade, accurate identification and complete eradication of tumor cells remain a great challenge owing to the limitation of single imaging modality and therapeutic strategy.

Results

Herein, we successfully design and construct BiVO₄/Fe₃O₄@polydopamine (PDA) superparticles (SPs) for computed tomography (CT)/photoacoustic (PA)/magnetic resonance (MR) multimodal imaging and radiotherapy (RT)/photothermal therapy (PTT) synergistic therapy toward oral epithelial carcinoma. On the one hand, BiVO₄ NPs endow BiVO₄/Fe₃O₄@PDA SPs with impressive X-ray absorption capability due to the high X-ray attenuation coefficient of Bi, which is beneficial for their utilization as radiosensitizers for CT imaging and RT. On the other hand, Fe₃O₄ NPs impart BiVO₄/Fe₃O₄@PDA SPs with the superparamagnetic property as a T₂-weighted contrast agent for MR imaging. Importantly, the aggregation of Fe₃O₄ NPs in SPs and the presence of PDA shell greatly improve the photothermal conversion capability of SPs, making BiVO₄/Fe₃O₄@PDA SPs as an ideal photothermal transducer for PA imaging and PTT. By integrating advantages of various imaging modalities (CT/PA/MR) and therapeutic strategies (RT/PTT), our BiVO₄/Fe₃O₄@PDA SPs exhibit the sensitive multimodal imaging feature and superior synergistic therapeutic efficacy on tumors.

Conclusions

Since there are many kinds of building blocks with unique properties appropriating for self-assembly, our work may largely enrich the library of nanomateirals for tumor diagnosis and treatment.

Reactive Oxygen Species-Regulating Strategies Based on Nanomaterials for Disease Treatment

Reactive oxygen species (ROS) play an essential role in physiological and pathological processes. Studies on the regulation of ROS for disease treatments have caused wide concern, mainly involving the topics in ROS-regulating therapy such as antioxidant therapy triggered by ROS scavengers and ROS-induced toxic therapy mediated by ROS-elevation agents. Benefiting from the remarkable advances of nanotechnology, a large number of nanomaterials with the ROS-regulating ability are developed to seek new and effective ROS-related nanotherapeutic modalities or nanomedicines. Although considerable achievements have been made in ROS-based nanomedicines for disease treatments, some fundamental but key questions such as the rational design principle for ROS-related nanomaterials are held in low regard. Here, the design principle can serve as the initial framework for scientists and technicians to design and optimize the ROS-regulating nanomedicines, thereby minimizing the gap of nanomedicines for biomedical application during the design stage. Herein, an overview of the current progress of ROS-associated nanomedicines in disease treatments is summarized. And then, by particularly addressing these known strategies in ROS-associated therapy, several fundamental and key principles for the design of ROS-associated nanomedicines are presented. Finally, future perspectives are also discussed in depth for the development of ROS-associated nanomedicines.

A near-infrared light-responsive extracellular vesicle as a "Trojan horse" for tumor deep penetration and imaging-guided therapy

How to make the nanoparticles evade immune surveillance and deeply penetrate the tumor tissues is of great importance to maximize the therapeutic efficacy of nanomedicines. Here, a near-infrared (NIR) light-responsive extracellular vesicle as a nanoplatform is developed to realize long circulation in blood, deep penetration in tumor tissues and rapid body elimination after the treatment. Like a "Trojan horse", the nanoplatform is obtained by hiding the anti-tumor soldiers (DOX and 4.2 nm Ag₂S quantum dots (QDs)) into the macrophage cell-secreted vesicle through electroporation. The natural composition and tumor targeting activity of the extracellular vesicles enable the nanoplatform to achieve a high accumulation in tumor and the in vivo biodistribution can be monitored by NIR fluorescence imaging of the Ag₂S QDs. After the nanomedicines accumulate at the tumor sites, the soldiers will be released from the "Trojan horse" by utilizing the NIR photothermal effect of the Ag₂S QDs. The released ultrasmall QDs and DOX can penetrate the whole tumor with a diameter of about 9 mm and effectively kill the tumor cells. Moreover, the inorganic QDs can be rapidly excreted from the body through renal clearance after the treatment to avoid the potential toxicity.

Hollow PtCo alloy nanospheres as a high-Z and oxygen generating nanozyme for radiotherapy enhancement in non-small cell lung cancer

Radiotherapy, as well as chemotherapy and surgery, occupies an essential position in tumor treatment. Nonetheless, insufficient radiation deposition and hypoxia-related radioresistance of cancer cells still are serious challenges in radiotherapy. Herein, we proposed a hollow PtCo nanosphere (PtCo NS)-based novel radiosensitizer with three advantages to sensitize tumor radiotherapy: (i) the high-Z element Pt ensured higher radiation absorption to cause more DNA damage, (ii) the platinum (Pt) and cobalt (Co) elements exhibited a dual catalase-like enzymatic activity to convert endogenic H2O2 to O2 efficiently, and (iii) the unique hollow nature of the PtCo NS provided a large specific surface area, which could amplify the catalytic reaction of H2O2 to induce reactive oxygen species and cancer cell apoptosis upon combination with radiation. Both in vivo and in vitro studies showed that the hollow PtCo NS could significantly inhibit tumor growth, simultaneously relieving tumor hypoxia with good biocompatibility and biosafety. This work presents a simple but multifunctional radiosensitizer with a unique hollow structure for radiotherapy enhancement.

Protein sulfenic acid-mediated anchoring of gold nanoparticles for enhanced CT imaging and radiotherapy of tumors in vivo

Radiotherapy (RT) has become one of the most widely used treatments for malignant tumors in clinics. Developing a novel radiosensitizer for the integration of precise diagnosis and effective radiotherapy against hypoxic tumors is desirable but remains a great challenge. Herein, protein sulfenic acid reactive gold nanoparticles as effective radiosensitizers were for the first time reported for enhanced X-ray computed tomography (CT) imaging and radiotherapy of tumors in vivo. The gold nanoparticles were decorated with biocompatible poly(ethylene glycol), folic acid (FA), and sulfenic acid reactive groups 1,3-cyclohexanedione (CHD). Such a nanostructure enables on-site immobilization within tumors under oxidative stress through the specific reaction between CHD and endogenous protein sulfenic acids resulting in enhanced accumulation and retention of gold nanoparticles within tumors, which remarkably improves the sensitivity of CT imaging and the radiotherapeutic efficacy of tumors in living mice. This study thus is the first to demonstrate that protein sulfenic acid reactive gold nanoparticles with a tumor anchoring function may serve as effective radiosensitizers for clinical X-ray theranostic application in the future.