A novel property of gold nanoparticles: Free radical generation under microwave irradiation

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.

Aggregation-induced emission luminogens for highly effective microwave dynamic therapy

Aggregation-induced emission luminogens (AIEgens) exhibit efficient cytotoxic reactive oxygen species (ROS) generation capability and unique light-up features in the aggregated state, which have been well explored in image-guided photodynamic therapy (PDT). However, the limited penetration depth of light in tissue severely hinders AIEgens as a candidate for primary or adjunctive therapy for clinical applications. Coincidentally, microwaves (MWs) show a distinct advantage for deeper penetration depth in tissues than light. Herein, for the first time, we report AIEgen-mediated microwave dynamic therapy (MWDT) for cancer treatment. We found that two AIEgens (TPEPy-I and TPEPy-PF6) served as a new type of microwave (MW) sensitizers to produce ROS, including singlet oxygen (1O2), resulting in efficient destructions of cancer cells. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and live/dead assays reveal that the two AIEgens when activated by MW irradiation can effectively kill cancer cells with average IC-50 values of 2.73 and 3.22 μM, respectively. Overall, the ability of the two AIEgens to be activated by MW not only overcomes the limitations of conventional PDT, but also helps to improve existing MW ablation therapy by reducing the MW dose required to achieve the same therapeutic outcome, thus reducing the occurrence of side-effects of MW radiation.

Nanomaterials responding to microwaves: an emerging field for imaging and therapy

In recent years, new microwave-based imaging, sensing and hyperthermia applications have emerged in the field of diagnostics and therapy. For diagnosis, this technology involves the application of low power microwaves, utilising contrast between the relative permittivity of tissues to identify pathologies. This contrast can be further enhanced through the implementation of nanomaterials. For therapy, this technology can be applied in tissues either through hyperthermia, which can help anti-cancer drug tumour penetration or as ablation to destroy malignant tissues. Nanomaterials can absorb electromagnetic radiation and can enhance the microwave hyperthermic effect. In this review we aim to introduce this area of renewed interest and provide insights into current developments in its technologies and companion nanoparticles, as well as presenting an overview of applications for diagnosis and therapy.

Remotely Activated Nanoparticles for Anticancer Therapy

Cancer has nowadays become one of the leading causes of death worldwide. Conventional anticancer approaches are associated with different limitations. Therefore, innovative methodologies are being investigated, and several researchers propose the use of remotely activated nanoparticles to trigger cancer cell death. The idea is to conjugate two different components, i.e., an external physical input and nanoparticles. Both are given in a harmless dose that once combined together act synergistically to therapeutically treat the cell or tissue of interest, thus also limiting the negative outcomes for the surrounding tissues. Tuning both the properties of the nanomaterial and the involved triggering stimulus, it is possible furthermore to achieve not only a therapeutic effect, but also a powerful platform for imaging at the same time, obtaining a nano-theranostic application. In the present review, we highlight the role of nanoparticles as therapeutic or theranostic tools, thus excluding the cases where a molecular drug is activated. We thus present many examples where the highly cytotoxic power only derives from the active interaction between different physical inputs and nanoparticles. We perform a special focus on mechanical waves responding nanoparticles, in which remotely activated nanoparticles directly become therapeutic agents without the need of the administration of chemotherapeutics or sonosensitizing drugs.

Redox interactions and genotoxicity of metal-based nanoparticles: A comprehensive review

Nanotechnology is a growing science that may provide several new applications for medicine, food preservation, diagnostic technologies, and sanitation. Despite its beneficial applications, there are several questions related to the safety of nanomaterials for human use. The development of nanotechnology is associated with some concerns because of the increased risk of carcinogenesis following exposure to nanomaterials. The increased levels of reactive oxygen species (ROS) that are due to exposure to nanoparticles (NPs) are primarily responsible for the genotoxicity of metal NPs. Not all, but most metal NPs are able to directly produce free radicals through the release of metal ions and through interactions with water molecules. Furthermore, the increased production of free radicals and the cell death caused by metal NPs can stimulate reduction/oxidation (redox) reactions, leading to the continuous endogenous production of ROS in a positive feedback loop. The overexpression of inflammatory mediators, such as NF-kB and STATs, the mitochondrial malfunction and the increased intracellular calcium levels mediate the chronic oxidative stress that occurs after exposure to metal NPs. In this paper, we review the genotoxicity of different types of metal NPs and the redox mechanisms that amplify the toxicity of these NPs.

Tumor-facing hepatocytes significantly contribute to mild hyperthermia-induced targeting of rat liver metastasis by PLGA-NPs

The effect of mild hyperthermia (MHT) on nanoparticle (NP) accumulation in rat model liver metastasis and the contribution of neoplastic and non-neoplastic cells were characterized. CdSe/ZnS QD-doped poly(lactic-co-glycolic acid) (PLGA) NPs (155 ± 10 nm) were delivered via the ileocolic vein to metastatic livers 15 min after localized MW irradiation (1 min, 41 °C) or in normothermia (37 °C, NT). Quantitative analysis of tissue sections by confocal fluorescence microscopy 1 h after NP injection showed no NP tumor accumulation in NT. On the contrary, MHT increased NP association with tumor, compared to normal tissue. Counterstaining of specific markers showed that the MHT effect is due to an increased NP endocytosis not only by tumor cells, but also by hepatocytes at the growing tumor edge and, to a minor extent, by tumor-associated macrophages. High-NP capturing hepatocytes, close to the tumor, may be a relevant phenomenon in MHT-induced increased targeting of NPs to liver metastasis, influencing their therapeutic efficacy.

A facile method for the synthesis of copper–cysteamine nanoparticles and study of ROS production for cancer treatment

A facile synthesis method of copper–cysteamine nanoparticles is reported and their application for cancer treatment through ROS-mediated mechanisms is explored.

Decorated Superparamagnetic Iron Oxide Nanoparticles with Monoclonal Antibody and Diethylene-Triamine-Pentaacetic Acid Labeled with Thechnetium-99m and Galium-68 for Breast Cancer Imaging

PURPOSE

In this study we developed and tested an iron oxide nanoparticle conjugated with DTPA and Trastuzumab, which can efficiently be radiolabeled with 99m-Tc and Ga-68, generating a nanoradiopharmaceutical agent to be used for SPECT and PET imaging.

METHODS

The production of iron oxide nanoparticle conjugated with DTPA and Trastuzumab was made using phosphorylethanolamine (PEA) surface modification. Both radiolabeling process was made by the direct radiolabeling of the nanoparticles. The in vivo assay was done in female Balb/c nude mice xenografted with breast cancer. Also a planar imaging using the radiolabeled nanoparticle was performed.

RESULTS

No thrombus and immune response leading to unwanted interaction and incorporation of nanoparticles by endothelium and organs, except filtration by the kidneys, was observed. In fact, more than 80% of ^99mTc-DTPA-TZMB@Fe₃O₄ nanoparticles seems to be cleared by the renal pathway but the implanted tumor whose seems to increase the expression of HER2 receptors enhancing the uptake by all other organs.

CONCLUSION

However, even in this unfavorable situation the tumor bioconcentrated much larger amounts of the nano-agent than normal tissues giving clear enough contrast for breast cancer imaging for diagnostics purpose by both SPECT and PET technique. Graphical Abstract ᅟ.