Non-invasive Photodynamic Therapy in Brain Cancer by Use of Tb3+-Doped LaF3 Nanoparticles in Combination with Photosensitizer Through X-ray Irradiation: A Proof-of-Concept Study

Innovative lanthanide complexes: Shaping the future of cancer/ tumor chemotherapy

Developing new therapeutic and diagnostic metals and metal complexes is a stunning example of how inorganic chemistry is rapidly becoming an essential part of modern medicine. More study of bio-coordination chemistry is needed to improve the design of compounds with fewer harmful side effects. Metal-containing drugs are widely utilized in the treatment of cancer. Platinum complexes are effective against some cancers, but new coordination compounds are being created with improved pharmacological properties and a broader spectrum of anticancer action. The coordination complexes of the 15 lanthanides or rare earth elements in the periodic table are crucial for diagnosing and treating cancer. Understanding and treating cancer requires the detection of binding lanthanide (III) ions or complexes to DNA and breaking DNA by these complexes. Current advances in lanthanide-based coordination complexes as anticancer treatments over the past five years are discussed in this study.

Photosensitizers for Photodynamic Therapy of Brain Cancers-A Review

On average, there are about 300,000 new cases of brain cancer each year. Studies have shown that brain and central nervous system tumors are among the top ten causes of death. Due to the extent of this problem and the percentage of patients suffering from brain tumors, innovative therapeutic treatment methods are constantly being sought. One such innovative therapeutic method is photodynamic therapy (PDT). Photodynamic therapy is an alternative and unique technique widely used in dermatology and other fields of medicine for the treatment of oncological and nononcological lesions. Photodynamic therapy consists of the destruction of cancer cells and inducing inflammatory changes by using laser light of a specific wavelength in combination with the application of a photosensitizer. The most commonly used photosensitizers include 5-aminolevulinic acid for the enzymatic generation of protoporphyrin IX, Temoporfin-THPC, Photofrin, Hypericin and Talaporfin. This paper reviews the photosensitizers commonly used in photodynamic therapy for brain tumors. An overview of all three generations of photosensitizers is presented. Along with an indication of the limitations of the treatment of brain tumors, intraoperative photodynamic therapy and its possibilities are described as an alternative therapeutic method.

Recent Clinical and Preclinical Advances in External Stimuli-Responsive Therapies for Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) has long been one of the most prevalent cancers worldwide; even though treatments such as surgery, chemotherapy, radiotherapy and immunotherapy have been proven to benefit the patients and prolong their survival time, the overall five-year survival rate is still below 50%. Hence, the development of new therapies for better patient management is an urgent need. External stimuli-responsive therapies are emerging therapies with promising antitumor effects; therapies such as photodynamic (PDT) and photothermal therapies (PTT) have been tested clinically in late-stage HNSCC patients and have achieved promising outcomes, while the clinical translation of sonodynamic therapy (SDT), radiodynamic therapy (RDT), microwave dynamic/thermodynamic therapy, and magnetothermal/magnetodynamic therapy (MDT/MTT) still lag behind. In terms of preclinical studies, PDT and PTT are also the most extensively studied therapies. The designing of nanoparticles and combinatorial therapies of PDT and PTT can be referenced in designing other stimuli-responsive therapies in order to achieve better antitumor effects as well as less toxicity. In this review, we consolidate the advancements and limitations of various external stimuli-responsive therapies, as well as critically discuss the prospects of this type of therapies in HNSCC treatments.

Enhanced Photodynamic Therapy: A Review of Combined Energy Sources

Photodynamic therapy (PDT) has been used in recent years as a non-invasive treatment for cancer, due to the side effects of traditional treatments such as surgery, radiotherapy, and chemotherapy. This therapeutic technique requires a photosensitizer, light energy, and oxygen to produce reactive oxygen species (ROS) which mediate cellular toxicity. PDT is a useful non-invasive therapy for cancer treatment, but it has some limitations that need to be overcome, such as low-light-penetration depths, non-targeting photosensitizers, and tumor hypoxia. This review focuses on the latest innovative strategies based on the synergistic use of other energy sources, such as non-visible radiation of the electromagnetic spectrum (microwaves, infrared, and X-rays), ultrasound, and electric/magnetic fields, to overcome PDT limitations and enhance the therapeutic effect of PDT. The main principles, mechanisms, and crucial elements of PDT are also addressed.

Nanoscintillator-Based X-Ray-Induced Photodynamic Therapy

Photodynamic therapy (PDT) is an emerging treatment option for cancer. In PDT, photosensitizers are delivered to tumors and stimulated by light to generate reactive oxygen species (ROS)-most importantly singlet oxygen (¹O₂)-to damage tumor cells or induce tissue ischemia. PDT is associated with a low level of systemic toxicity because photosensitizers are usually pharmaceutically inactive in the dark and photoirradiation is applied only to tumor areas in the procedure. Additionally, PDT can be applied repeatedly without cumulative toxicity or incurring resistance, and may stimulate systemic anti-tumor immunity. However, PDT's clinical use has been restricted due to the limited penetration of visible light through tissues. X-rays possess superior tissue penetration capability and are exploited in X-ray-induced photodynamic therapy to overcome this limitation. Herein we have demonstrated this principle with a novel LiGa₅O₈:Cr (LGO:Cr)-based nanoscintillator which emits near-infrared X-ray luminescence to both guide external beam therapy and induce PDT with the photosensitizer (2,3-naphthalocyanine) encapsulated in a mesoporous silica shell of the nanoscintillator.

The Rare-Earth Elements Doping of BaGdF5 Nanophosphors for X-ray Photodynamic Therapy

It is known that the initiation of photodynamic therapy (PDT) in deep-seated tumors requires the use of X-rays to activate the reactive oxygen species generation in deep tissues. The aim of this paper is to synthesize X-ray nanophosphors and analyze their structural and luminescence characteristics to push the PDT process deep into the body. The article deals with BaGdF5:Eu3+, BaGdF5:Sm3+, and BaGdF5:Tb3+ nanophosphors synthesized using microwave synthesis. It is found that the nanoparticles are biocompatible and have sizes 5-17 nm. However, according to the analysis of X-ray excited optical luminescence, BaGdF5:Sm3+ nanophosphors will not be effective for treating deep-seated tumors. Thus, BaGdF5:Eu3+ and BaGdF5:Tb3+ nanoparticles meet the requirements for the subsequent production of nanocomposites based on them that can be used in X-ray photodynamic therapy.

Progress in Nanocarriers Codelivery System to Enhance the Anticancer Effect of Photodynamic Therapy

Photodynamic therapy (PDT) is a promising anticancer noninvasive method and has great potential for clinical applications. Unfortunately, PDT still has many limitations, such as metastatic tumor at unknown sites, inadequate light delivery and a lack of sufficient oxygen. Recent studies have demonstrated that photodynamic therapy in combination with other therapies can enhance anticancer effects. The development of new nanomaterials provides a platform for the codelivery of two or more therapeutic drugs, which is a promising cancer treatment method. The use of multifunctional nanocarriers for the codelivery of two or more drugs can improve physical and chemical properties, increase tumor site aggregation, and enhance the antitumor effect through synergistic actions, which is worthy of further study. This review focuses on the latest research progress on the synergistic enhancement of PDT by simultaneous multidrug administration using codelivery nanocarriers. We introduce the design of codelivery nanocarriers and discuss the mechanism of PDT combined with other antitumor methods. The combination of PDT and chemotherapy, gene therapy, immunotherapy, photothermal therapy, hyperthermia, radiotherapy, sonodynamic therapy and even multidrug therapy are discussed to provide a comprehensive understanding.

Pure photosensitizer-driven nanoassembly with core-matched PEGylation for imaging-guided photodynamic therapy

Pure drug-assembled nanomedicines (PDANs) are currently under intensive investigation as promising nanoplatforms for cancer therapy. However, poor colloidal stability and less tumor-homing ability remain critical unresolved problems that impede their clinical translation. Herein, we report a core-matched nanoassembly of pyropheophorbide a (PPa) for photodynamic therapy (PDT). Pure PPa molecules are found to self-assemble into nanoparticles (NPs), and an amphiphilic PEG polymer (PPa-PEG_2K) is utilized to achieve core-matched PEGylating modification via the π‒π stacking effect and hydrophobic interaction between the PPa core and the PPa-PEG_2K shell. Compared to PCL-PEG_2K with similar molecular weight, PPa-PEG_2K significantly increases the stability, prolongs the systemic circulation and improves the tumor-homing ability and ROS generation efficiency of PPa-nanoassembly. As a result, PPa/PPa-PEG_2K NPs exert potent antitumor activity in a 4T1 breast tumor-bearing BALB/c mouse xenograft model. Together, such a core-matched nanoassembly of pure photosensitizer provides a new strategy for the development of imaging-guided theragnostic nanomedicines.

Nanobiotechnology-assisted therapies to manage brain cancer in personalized manner

There are numerous investigated factors that limit brain cancer treatment efficacy such as ability of prescribed therapy to cross the blood-brain barrier (BBB), tumor specific delivery of a therapeutics, transport within brain interstitium, and resistance of tumor cells against therapies. Recent breakthroughs in the field of nano-biotechnology associated with developing multifunctional nano-theranostic emerged as an effective way to manage brain cancer in terms of higher efficacy and least possible adverse effects. Keeping challenges and state-of-art accomplishments into consideration, this review proposes a comprehensive, careful, and critical discussion focused on efficient nano-enabled platforms including nanocarriers for drug delivery across the BBB and nano-assisted therapies (e.g., nano-immunotherapy, nano-stem cell therapy, and nano-gene therapy) investigated for brain cancer treatment. Besides therapeutic efficacy point-of-view, efforts are being made to explore ways projected to tune such developed nano-therapeutic for treating patients in personalized manner via controlling size, drug loading, delivery, and retention. Personalized brain tumor management based on advanced nano-therapies can potentially lead to excellent therapeutic benefits based on unique genetic signatures in patients and their individual disease profile. Moreover, applicability of nano-systems as stimulants to manage the brain cancer growth factors has also been discussed in photodynamic therapy and radiotherapy. Overall, this review offers a comprehensive information on emerging opportunities in nanotechnology for advancing the brain cancer treatment.

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.

Terbium-Based AGuIX-Design Nanoparticle to Mediate X-ray-Induced Photodynamic Therapy

X-ray-induced photodynamic therapy is based on the energy transfer from a nanoscintillator to a photosensitizer molecule, whose activation leads to singlet oxygen and radical species generation, triggering cancer cells to cell death. Herein, we synthesized ultra-small nanoparticle chelated with Terbium (Tb) as a nanoscintillator and 5-(4-carboxyphenyl succinimide ester)-10,15,20-triphenyl porphyrin (P1) as a photosensitizer (AGuIX@Tb-P1). The synthesis was based on the AGuIX@ platform design. AGuIX@Tb-P1 was characterised for its photo-physical and physico-chemical properties. The effect of the nanoparticles was studied using human glioblastoma U-251 MG cells and was compared to treatment with AGuIX@ nanoparticles doped with Gadolinium (Gd) and P1 (AGuIX@Gd-P1). We demonstrated that the AGuIX@Tb-P1 design was consistent with X-ray photon energy transfer from Terbium to P1. Both nanoparticles had similar dark cytotoxicity and they were absorbed in a similar rate within the cells. Pre-treated cells exposure to X-rays was related to reactive species production. Using clonogenic assays, establishment of survival curves allowed discrimination of the impact of radiation treatment from X-ray-induced photodynamic effect. We showed that cell growth arrest was increased (35%-increase) when cells were treated with AGuIX@Tb-P1 compared to the nanoparticle doped with Gd.

Functionalized Scintillating Nanotubes for Simultaneous Radio- and Photodynamic Therapy of Cancer

As a model radio-photodynamic therapy (RPDT) agent, we developed a multicomponent nanomaterial by anchoring conjugated chromophores on the surface of scintillating chrysotile nanotubes. Its ultimate composition makes the system a scintillation-activated photosensitizer for the singlet oxygen production. This nanomaterial shows a remarkable ability to enhance the production of singlet oxygen in an aqueous environment, under X-ray irradiation, boosting its production by almost 1 order of magnitude. Its efficiency as a coadjutant for radiotherapy has been tested in vitro, showing a striking efficacy in enhancing both the prompt cytotoxicity of the ionizing radiation and the long-term cytotoxicity given by radiation-activated apoptosis. Notably, the beneficial activity of the RPDT agent is prominent at low levels of delivered doses comparable to the one employed in clinical treatments. This opens the possibility of effectively reducing the therapy exposure and consequently undesired collateral effects due to prolonged exposure of patients to high-energy radiation.

Can Cerenkov Light Really Induce an Effective Photodynamic Therapy?

Photodynamic therapy (PDT) is a promising therapeutic strategy for cancers where surgery and radiotherapy cannot be effective. PDT relies on the photoactivation of photosensitizers, most of the time by lasers to produced reactive oxygen species and notably singlet oxygen. The major drawback of this strategy is the weak light penetration in the tissues. To overcome this issue, recent studies proposed to generate visible light in situ with radioactive isotopes emitting charged particles able to produce Cerenkov radiation. In vitro and preclinical results are appealing, but the existence of a true, lethal phototherapeutic effect is still controversial. In this article, we have reviewed previous original works dealing with Cerenkov-induced PDT (CR-PDT). Moreover, we propose a simple analytical equation resolution to demonstrate that Cerenkov light can potentially generate a photo-therapeutic effect, although most of the Cerenkov photons are emitted in the UV-B and UV-C domains. We suggest that CR-PDT and direct UV-tissue interaction act synergistically to yield the therapeutic effect observed in the literature. Moreover, adding a nanoscintillator in the photosensitizer vicinity would increase the PDT efficacy, as it will convert Cerenkov UV photons to light absorbed by the photosensitizer.

Tanshinone IIA Suppresses Glioma Cell Proliferation, Migration and Invasion Both in vitro and in vivo Partially Through miR-16-5p/Talin-1 (TLN1) Axis

Background

Tanshinone IIA (TIIA) is one of the active constituents derived from the rhizome of Danshen, a traditional Chinese herbal. Recently, microRNAs (miRNAs) have been suggested to be associated with the anticancer role of TIIA. However, it remains vague of the interaction between miRNAs and TIIA in glioma, a common aggressive brain tumor in humans.

Methods

Expression of miRNA (miR)-16-5p and talin-1 (TLN1) was detected using reverse transcription-quantitative polymerase chain reaction and Western blotting. Cell proliferation, migration and invasion were assessed with cell viability assay, transwell assay, Western blotting, and xenograft tumor experiment. The target binding between miR-16-5p and TLN1 was confirmed by dual-luciferase reporter assay and RNA pull-down assay.

Results

TIIA treatment inhibited cell viability, migration and invasion, and decreased Cyclin D1, matrix metalloproteinase (MMP)-9 and Vimentin expression in glioma T98G and A172 cells both in vitro and in vivo. Thus, TIIA induced anti-glioma role, wherein miR-16-5p was upregulated and TLN1 was downregulated. Moreover, silencing miR-16-5p could abate TIIA-mediated suppression on glioma cell proliferation, migration and invasion in vitro and in vivo. TLN1 overexpression also exerted tumor-promoting effect in TIIA-treated T98G and A172 cells. Mechanically, miR-16-5p could regulate TLN1 expression via target binding, and depleting TLN1 could counteract the inhibitory effect of miR-16-5p knockdown on the curative effect of TIIA in T98G and A172 cells.

Conclusion

TIIA exerted the anti-proliferation, anti-migration and anti-invasion role in glioma cells both in vitro and in vivo partially through regulating miR-16-5p/TLN1 axis.

Camouflaged, activatable and therapeutic tandem bionanoreactors for breast cancer theranosis

The one-pot cascade reaction of naturally occurring enzymes is exciting for highly selective complex reaction and biodegradable approaches. Tamoxifen is the main drug against breast cancer for decades and induces an anticancerous effect upon metabolic activation by cytochrome P450 (CYP450). Herein, bi-enzymatic nanoreactors (NRs) are developed as a multimodality platform for smart action against breast tumors. CYP_BM3 of Bacillus magaterium (CYP) is co-confined with glucose oxidase (GOx) where GOx produces H₂O₂ in the presence of glucose that elicits the CYP-mediated transformation of tamoxifen. The scintillating and mesoporous LaF₃:Tb as nanocarrier showed advantages like a wide range of pore size and positive surface charge for efficient loading of enzyme couple, while the smallest pores were available for substrate/product diffusion. The obtained NRs were camouflaged with human serum albumin (HSA) to overcome premature enzyme leaching and provide active stealth properties. The nanocomposite was characterized for physicochemical properties and glucose-mediated sequential catalysis. The in vitro studies demonstrated the cell internalization of NRs in both ER+ and triple-negative breast cancer cell lines and showed significant cytotoxicity. The developed NRs not only improve the outcomes of endocrine therapy in ER+ cells but also synergistically act with oxidation therapy for enhanced therapeutic effect. Importantly, inhibition of triple-negative cells was also achieved. Thus, the development of the new multimodal nanomedicine of the present work should afford new tools towards the theranosis of breast cancer with minimized adverse effects.

Radiation Dose-Enhancement Is a Potent Radiotherapeutic Effect of Rare-Earth Composite Nanoscintillators in Preclinical Models of Glioblastoma

To improve the prognosis of glioblastoma, innovative radiotherapy regimens are required to augment the effect of tolerable radiation doses while sparing surrounding tissues. In this context, nanoscintillators are emerging radiotherapeutics that down-convert X-rays into photons with energies ranging from UV to near-infrared. During radiotherapy, these scintillating properties amplify radiation-induced damage by UV-C emission or photodynamic effects. Additionally, nanoscintillators that contain high-Z elements are likely to induce another, currently unexplored effect: radiation dose-enhancement. This phenomenon stems from a higher photoelectric absorption of orthovoltage X-rays by high-Z elements compared to tissues, resulting in increased production of tissue-damaging photo- and Auger electrons. In this study, Geant4 simulations reveal that rare-earth composite LaF3:Ce nanoscintillators effectively generate photo- and Auger-electrons upon orthovoltage X-rays. 3D spatially resolved X-ray fluorescence microtomography shows that LaF3:Ce highly concentrates in microtumors and enhances radiotherapy in an X-ray energy-dependent manner. In an aggressive syngeneic model of orthotopic glioblastoma, intracerebral injection of LaF3:Ce is well tolerated and achieves complete tumor remission in 15% of the subjects receiving monochromatic synchrotron radiotherapy. This study provides unequivocal evidence for radiation dose-enhancement by nanoscintillators, eliciting a prominent radiotherapeutic effect. Altogether, nanoscintillators have invaluable properties for enhancing the focal damage of radiotherapy in glioblastoma and other radioresistant cancers.

A mini-review of X-ray photodynamic therapy (XPDT) nonoagent constituents' safety and relevant design considerations

Conventional photodynamic therapy (PDT) has proved effective in the management of primary tumors and individual metastases. However, most cancer mortality arises from wide-spread multiple metastases. The latter has thus become the principal target in oncology, and X-ray induced photodynamic therapy (XPDT or PDTX) offers a great solution for adapting the PDT principle to deep tumors and scattered metastases. Developing agents capable of being excited by X-rays and emitting visible light to excite photosensitizers is based on challenging physical and chemical technologies, but there are fundamental biological limitations that are to be accounted for as well. In the present review, we have established eight major groups of safety determinants of NPs encompassing 22 parameters of clinical applicability of XPDT nanoparticulate formulations. Most, if not all, of these parameters can be accounted for and optimized during the design and development of novel XPDT nanoparticles.

Synthesis of Radioluminescent CaF2:Ln Core, Mesoporous Silica Shell Nanoparticles for Use in X-ray Based Theranostics

X-ray radiotherapy is a common method of treating cancerous tumors or other malignant lesions. The side effects of this treatment, however, can be deleterious to patient quality of life if critical tissues are affected. To potentially lower the effective doses of radiation and negative side-effects, new classes of nanoparticles are being developed to enhance reactive oxygen species production during irradiation. This report presents the synthesis and radiotherapeutic efficacy evaluation of a new nanoparticle formulation designed for this purpose, composed of a CaF2 core, mesoporous silica shell, and polyethylene glycol coating. The construct was additionally doped with Tb and Eu during the CaF2 core synthesis to prepare nanoparticles (NPs) with X-ray luminescent properties for potential application in fluorescence imaging. The mesoporous silica shell was added to provide the opportunity for small molecule loading, and the polyethylene glycol coating was added to impart aqueous solubility and biocompatibility. The potential of these nanomaterials to act as radiosensitizers for enhancing X-ray radiotherapy was supported by reactive oxygen species generation assays. Further, in vitro experiments indicate biocompatibility and enhanced cellular damage during X-ray radiotherapy.

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.

Application of photodynamic therapy drugs for management of glioma

Human gliomas are one of the most prevalent and challenging-to-treat adult brain tumors, and thus result in high morbidity and mortality rates worldwide. Current research and treatments of gliomas include surgery associated with conventional chemotherapy, use of biologicals, radiotherapy, and medical device applications. The selected treatment options are often guided by the category and aggressiveness of this deadly disease and the patient’s conditions. However, the effectiveness of these approaches is still limited due to poor drug efficacy (including delivery to desired sites), undesirable side effects, and high costs associated with therapies. In addition, the degree of leakiness of the blood–brain barrier (BBB) that regulates trafficking of molecules in and out of the brain also modulates accumulation of adequate drug levels to tumor sites. Active research is being pursued to overcome these limitations to obtain a superior therapeutic index and enhanced patient survival. One area of development in this direction focuses on the localized application of photodynamic therapy (PDT) drugs to cure brain cancers. PDT molecules potentially utilize multiple pathways based on their ability to generate reactive oxygen species (ROS) upon photoactivation by a suitable light source. In this communication, we have attempted to provide a brief overview of PDT and cancer, photoactivation pathways, mechanism of tumor destruction, effect of PDT on tumor cell viability, immune activation, various research attempted by applying PDT in combination with novel strategies to treat glioma, role of BBB and clinical status of PDT therapy for glioma treatment.

Smart Hybrid Nanocomposite for Photodynamic Inactivation of Cancer Cells with Selectivity

Photodynamic therapy has been efficiently applied for cancer therapy. Here, we have fabricated the folic acid (FA)- and pheophorbide A (PA)-conjugated FA/PA@Fe₃O₄ nanoparticle (smart hybrid nanocomposite, SHN) to enhance the photodynamic inactivation (PDI) of specific cancer cells. SHN coated with the PDI agent is designed to have selectivity for the folate receptor (FR) expressed on cancer cells. Structural characteristics and morphology of the fabricated MNPs were studied with X-ray diffraction and scanning electron microscopy. The photophysical properties of SHN were investigated with absorption, emission spectroscopies, and Fourier transform infrared spectroscopy. In addition, the magnetic property of Fe₃O₄ nanoparticle (MNP) can be utilized for the collection of SHNs by an external magnetic field. The photofunctionality was given by the photosensitizer, PA, which generates reactive oxygen species by irradiation of visible light. Generation of singlet oxygen was directly evaluated with time-resolved phosphorescence spectroscopy. Biocompatibility and cellular interaction of SHN were also analyzed by using various cancer cells, such as KB, HeLa, and MCF-7 cells which express different levels of FR on the surface. Cellular adsorption and the PDI effect of SHN on the various cancer cells in vitro were correlated well with the surface expression levels of FR, suggesting potential applicability of SHN on specific targeting and PDI of FR-positive cancers.

Low dose photodynamic therapy harmonizes with radiation therapy to induce beneficial effects on pancreatic heterocellular spheroids

Photodynamic therapy (PDT) has seen long standing interest as a therapy for resistant cancers, but the main Achilles’ heel for its successful clinical exploitation is the use of poorly penetrating visible light. This limitation could be overcome by using radioluminescent nanoparticles, which can be excited during radiation therapy (RT) with penetrating X-rays. When infused in tumors, X-ray activated-nanoscintillators act as internal light sources and excite nearby photosensitizers. Recent studies demonstrated that it is realistic to achieve low dose PDT with current nanoscintillators. However, as the origin of enhanced RT efficacy with nanoscintillators may have varying origins, we aimed to answer the basic question: Is a combination of low-dose PDT beneficial to the RT efficacy in clinically relevant models of cancer?

Pancreatic cancer (PanCa) remains a lethal disease for which RT is part of the palliative care and for which PDT demonstrated promising results in clinical trial. We thus evaluated the combination of low-dose PDT and RT delivered in absence of nanoscintillators on various heterocellular spheroid models that recapitulate the clinical heterogeneity of PanCa. Although therapeutic effects emerged at different timepoints in each model, the RT/PDT combination uniformly achieved favorable outcomes. With RT providing stunted tumor growth while PDT drove adjuvant apoptotic and necrotic cell death, the combination produced significantly smaller and less viable PanCa spheroids.

In conclusion, the beneficial RT/PDT treatment outcomes encourage the further development of nanoscinitillators for X-ray-activated PDT. Assessment of such combination treatments should encompass multiparametric and temporally-spaced assessment of treatment effects in preclinical cancer models.

Approaches to physical stimulation of metallic nanoparticles for glioblastoma treatment

Glioblastoma multiforme (GBM) is the most aggressive malignant brain tumor. Despite new knowledges on the genetic characteristics, conventional therapy for GBM, tumor resection followed by radiotherapy and chemotherapy using temozolomide is limited in efficacy due to high rate of recurrence. GBM is indeed one of the most complex and difficult cancer to treat mainly due to its highly invasive properties and the standard treatments are thus rarely curative. Major challenges in the treatment of GBM are the limitation of irreversible brain damage, the infiltrative part of the tumor which is the ultimate cause of recurrence, the difficulty of identifying tumor margins and disseminated tumor cells, and the transport across the blood-brain barrier in order to obtain a sufficient therapeutic effect for pharmalogical agents. Considering these limitations, this review explores the in vivo potential of metal-based nanoparticles for hyperthermia, radiotherapy and photodynamic therapy. This article describes and clearly outlines the recent in vivo advances using innovative therapeutic metallic nanoparticles such as iron oxide, silver, gadolinium and gold nanoparticles.

New CeF3-ZnO nanocomposites for self-lighted photodynamic therapy that block adenocarcinoma cell life cycle

AIM

To synthesize and characterize the performances of a new all-inorganic nanocomposite (NC) for self-lighted photodynamic therapy against cancer. This NC could allow radiotherapy doses to be reduced, as it enhances the effects of x-rays, generating cytotoxic reactive oxygen species as singlet oxygen.

MATERIALS & METHODS

The proposed NC combines CeF₃ and ZnO; CeF₃ absorbs 6-MeV x-rays and activates the photosensitizer ZnO. Characterization is performed by transmission electron microscopy (TEM), scanning-TEM, energy dispersive x-ray spectrometry and fluorescence spectroscopies. Efficiency on human adenocarcinoma cells (A549) was tested by fluorescence spectroscopy, cytofluorimetry, viability assays, clonogenic assays, cell cycle progression assays.

RESULTS

NC blocks A549's cell cycle before mitosis in the dark. Upon low-dose x-ray irradiation (2 Gy), reactive oxygen species/singlet oxygen are generated, further blocking cell cycle and reducing viability by 18% with respect to the sum of x-ray irradiation and NC dark activity.

CONCLUSION

These novel NCs promise to reduce doses in radiotherapy, helping to reduce unwanted side effects.

Reduction-sensitive polypeptide nanogel conjugated BODIPY-Br for NIR imaging-guided chem/photodynamic therapy at low light and drug dose

A heavy atoms modified reaction-active photosensitizer NHS-BODIPY-Br possessing efficient near infrared (NIR) fluorescence emission and singlet oxygen generation properties has been synthesized, which can be used for synchronous NIR imaging and photodynamic therapy (PDT). A reduction-sensitive PEGylated polypeptide nanogel was prepared by ring-opening polymerization (ROP) of l-cystine-N-carboxy anhydride. Poly (ethylene glycol) methyl ether was used as initiator and hydrophilic segment, the as-prepared nanogel was conjugated with the NHS-BODIPY-Br molecule by chemical linkage, and it can be directly used as a macrophotosentizer for NIR imaging-guided PDT. In addition, the nanogel also showed good encapsulating ability for doxorubicin (DOX). In the presence of glutathione (10 mM), the obtained NIR nanogel showed obvious reduction-induced drug release behavior. In vitro tests on internalization of the NIR nanogel by HepG2 cells indicated its efficiency in detecting cancer cells. Meanwhile, MTT assays performed on HepG2 cells confirmed that the cancer cells growth could be obviously suppressed (almost all cells) when exposed to an extremely low energy light (25 mW/cm², 10-15 J/cm²) and low dose of DOX (3-5 μg/ml), indicates an efficient NIR image-guided chem/photodynamic therapy.

Pollen-Structured Gold Nanoclusters for X-ray Induced Photodynamic Therapy

Photodynamic therapy (PDT) is a cancer treatment that employs the production of cytotoxic reactive oxygen species (ROS), subsequently triggering tumor apoptosis and tumor size reduction. However, this approach suffers from insufficient light penetration depth. In order to mitigate this issue, pollen-structured gold clusters (PSGCs) were designed for mediating X-ray-induced PDT for radiotherapy enhancement. The structure of PSGCs provides a large surface area that is able to generate ROS upon X-ray irradiation. The synthesized PSGCs were exposed to different X-ray doses and the generated ROS was then quantified by dihydroethidium (DHE) assay. Furthermore, at the cellular level, the PDT efficacy of PSGCs was evaluated via immunofluorescence staining with γ-H2AX and comet assay. The results demonstrated that PSGCs possess a significantly high ROS-generating capacity and a remarkable PDT efficacy in the treatment of breast cancer cells, thus showing potential clinical uses in deep-tissue cancer treatment.

Uptake of Chlorin e6 Photosensitizer by Polystyrene-Diphenyloxazole-Poly(N-Isopropylacrylamide) Hybrid Nanosystem Studied by Electronic Excitation Energy Transfer

Polystyrene (PS)-diphenyloxazole (PPO) nanoparticles with attached cross-linked poly-N-isopropylacrylamide (PNIPAM) chains were obtained resulting in PS-PPO-PNIPAM hybrid nanosystems (NS). Fluorescence spectra of chlorin e₆ added to PS-PPO-PNIPAM hybrid NS revealed electronic excitation energy transfer (EEET) from PS matrix and encapsulated PPO to chlorin e₆. EEET efficiency increased strongly during 1 h after chlorin e₆ addition, indicating that uptake of chlorin e₆ by PNIPAM part of hybrid NS still proceeds during this time. Heating of PS-PPO-PNIPAM-chlorin e₆ NS from 21 to 39 °C results in an enhancement of EEET efficiency; this is consistent with PNIPAM conformation transition that reduces the distance between PS-PPO donors and chlorin e₆ acceptors. Meanwhile, a relatively small part of chlorin e₆ present in the solution is bound by PNIPAM; thus, further studies in this direction are necessary.

Magnetic-luminescent cerium-doped gadolinium aluminum garnet nanoparticles for simultaneous imaging and photodynamic therapy of cancer cells

Nanoparticle (NP) and photosensitizer (PS) conjugates capable of X-ray photodynamic therapy (X-PDT) are a research focus due to their potential applications in cancer treatment. Combined with X-PDT, appropriate imaging properties of the nanocomposite will make it suitable for theranostics of deep lying tumors. In this work, we describe the development of magnetic-luminescent Gd_2.98Ce_0.02Al₅O₁₂ nanoparticles (GAG) coated with mesoporous silica (mSiO₂) and loaded with rose bengal (RB) to yield a nanocomposite GAG@mSiO₂@RB capable of X-PDT. GAG nanoparticles were synthesized using the sol-gel method. The synthesized GAG nanoparticles showed a strong visible yellow emission with a quantum yield of ∼32%. Moreover, the broad emission spectra of GAG nanoparticles centered at 585 nm showed a good overlap with the absorption of RB. Upon irradiation with X-rays (55 KV), the GAG@mSiO₂@RB nanocomposite produced significantly higher singlet oxygen compared with RB alone, as confirmed by the 1,2-diphenylisobenzofuran (DPBF) assay. The developed GAG@mSiO₂@RB nanocomposite significantly reduced the viability of human breast cancer (MDA-MB-231) cells upon irradiation with blue light (λ = 470 nm). The calculated LC₅₀ of GAG@mSiO₂@RB nanocomposites were 26.69, 11.2, and 6.56 µg/mL at a dose of ∼0.16, 0.33 and 0.5 J/cm², respectively. Moreover, the nanocomposite showed paramagnetic properties with high magnetic mass susceptibility which are useful for high contrast T₁ weighted magnetic resonance imaging (MRI). Together with X-PDT, the paramagnetic properties of the proposed GAG@mSiO₂@RB nanocomposite system are promising for their future application in simultaneous detection and treatment of deep-lying tumors.

Reactive oxygen species generation in aqueous solutions containing GdVO4:Eu3+ nanoparticles and their complexes with methylene blue

It this letter, we report the study of free radicals and reactive oxygen species (ROS) generation in water solutions containing gadolinium orthovanadate GdVO4:Eu3+ nanoparticles (VNPs) and their complexes with methylene blue (MB) photosensitizer. The catalytic activity was studied under UV-Vis and X-ray irradiation by three methods (conjugated dienes test, OH· radical, and singlet oxygen detection). It has been shown that the VNPs-MB complexes reveal high efficiency of ROS generation under UV-Vis irradiation associated with both high efficiency of OH· radicals generation by VNPs and singlet oxygen generation by MB due to nonradiative excitation energy transfer from VNPs to MB molecules. Contrary to that under X-ray irradiation, the strong OH . radicals scavenging by VNPs has been observed.

Advancing porphyrin's biomedical utility via supramolecular chemistry

Porphyrins are organic heterocyclic macrocycles with photophysical properties well-suited for clinical phototherapy and cancer imaging. However, their wider application in the clinical management of disease is barred by poor aqueous solubility, bioavailability, tumour accumulation and skin phototoxicity. These limitations instigated the development of supramolecular platforms that improved porphyrin pharmacokinetics and tumour-homing. The supramolecular formulation of porphyrins also facilitates single agent-mediated deeper tissue photoactivation, extended imaging and theranostic multimodality, and synergistic application of multiple therapies. Supramolecular porphyrin structures can overcome additional limitations of porphyrin-mediated photodynamic therapy (PDT), including low depths of tissue penetration that restrict PDT to superficial lesions, inability to treat hypoxic tumours, and incomplete tumour damage. In this review, we discuss the photophysical properties of porphyrins, and overview the clinically-relevant advantages and challenges arising from their incorporation within supramolecular platforms. Specifically, fundamentals underlying the ability of these platforms to ameliorate passive and active porphyrin delivery to tumours, achieve deeper tissue PDT via red-shifted porphyrin Q-bands, energy transfer and sonodynamic effects, and enable new porphyrin-mediated theranostics and synergistic therapeutic capabilities will be explained and exemplified with seminal and cutting-edge in vivo studies.

Nanocarrier-Mediated Photochemotherapy and Photoradiotherapy

Photothermal therapy (PTT) and photodynamic therapy (PDT) both utilize light to induce a therapeutic effect. These therapies are rapidly gaining importance due to the noninvasiveness of light and the limited adverse effect associated with these treatments. However, most preclinical studies show that complete elimination of tumors is rarely observed. Combining PDT and PTT with chemotherapy or radiotherapy can improve the therapeutic outcome and simultaneously decrease side effects of these conventional treatments. Nanocarriers can help to facilitate such a combined treatment. Here, the most recent advancements in the field of photochemotherapy and photoradiotherapy, in which nanocarriers are employed, are reviewed.

Lanthanide-Doped Core-Shell-Shell Nanocomposite for Dual Photodynamic Therapy and Luminescence Imaging by a Single X-ray Excitation Source

Photodynamic therapy (PDT) could be highly selective and noninvasive, with low side effects as an adjuvant therapy for cancer treatment. Because excitation sources such as UV and visible lights for most of the photosensitizers do not penetrate deeply enough into biological tissues, PDT is useful only when the lesions are located within 10 mm below the skin. In addition, there is no prior example of theranostics capable of both PDT and imaging with a single deep-penetrating X-ray excitation source. Here we report a new theranostic scintillator nanoparticle (ScNP) composite in a core-shell-shell arrangement, that is, NaLuF₄:Gd(35%),Eu(15%)@NaLuF₄:Gd(40%)@NaLuF₄:Gd(35%),Tb(15%), which is capable of being excited by a single X-ray radiation source to allow potentially deep tissue PDT and optical imaging with a low dark cytotoxicity and effective photocytotoxicity. With the X-ray excitation, the ScNPs can emit visible light at 543 nm (from Tb³⁺) to stimulate the loaded rose bengal (RB) photosensitizer and cause death of efficient MDA-MB-231 and MCF-7 cancer cells. The ScNPs can also emit light at 614 and 695 nm (from Eu³⁺) for luminescence imaging. The middle shell in the core-shell-shell ScNPs is unique to separate the Eu³⁺ in the core and the Tb³⁺ in the outer shell to prevent resonance quenching between them and to result in good PDT efficiency. Also, it was demonstrated that although the addition of a mesoporous SiO₂ layer resulted in the transfer of 82.7% fluorescence resonance energy between Tb³⁺ and RB, the subsequent conversion of the energy from RB to generate ¹O₂ was hampered, although the loaded amount of the RB was almost twice that without the mSiO₂ layer. A unique method to compare the wt % and mol % compositions calculated by using the morphological transmission electron microscope images and the inductively coupled plasma elemental analysis data of the core, core-shell, and core-shell-shell ScNPs is also introduced.

Using X-rays in photodynamic therapy: an overview

Photodynamic therapy is a therapeutic option to treat cancer and other diseases.

Salvia miltiorrhiza extract dihydrotanshinone induces apoptosis and inhibits proliferation of glioma cells

Dihydrotanshinone, a functional food in China, is an effective anti-cardiovascular disease substance isolated from Salvia miltiorrhiza (S. miltiorrhiza). Glioma is considered to be fatal due to its poor prognosis and few effective therapeutic options. In this study, we investigated the anticancer effects of S. miltiorrhiza extract dihydrotanshinone on human glioma SHG-44 cells, by using 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide assay, Hoechst 33258 nuclear staining, Annexin V/propidium iodide double staining, as well as western blot analysis. The results showed that dihydrotanshinone effectively suppressed SHG-44 cells proliferation and induced apoptosis in both dose- and time-dependent manner. Moreover, we demonstrated that dihydrotanshinone increased the activation of caspases (caspase-3 and caspase-9) and the release of cytochrome c in SHG-44 cells. Overall, dihydrotanshinone could induce apoptosis and inhibit proliferation of glioma cells by regulating caspases and cytochrome c. This study suggests that dihydrotanshinone may serve as a potential treatment option for patients with glioma.

808nm light triggered black TiO2 nanoparticles for killing of bladder cancer cells

The black TiO₂ nanoparticles are synthesized via a facile calcination method combined with an in-situ controllable solid-state reaction approach. The results indicate that the photocatalyst with a narrow band gap of ~2.32 eV extends the photoresponse to visible light and near infrared region. And thus more reactive oxygen species can be obtained to induce the cell-killing under 808 nm light triggering. The as-obtained black TiO₂ nanoparticles exhibiting low toxicity, good biocompatibility and high anticancer effect in vitro, is demonstrated as efficient photosensitizers for phototherapy to kill the bladder cancer cells. These findings suggest that the facile synthetic black TiO₂ nanomaterials will have broad application in biomedicine.