TB@PLGA Nanoparticles for Photodynamic/Photothermal Combined Cancer Therapy with Single Near-Infrared Irradiation

Manganese Amplifies Photoinduced ROS in Toluidine Blue Carbon Dots to Boost MRI Guided Chemo/Photodynamic Therapy

The contrast agents and tumor treatments currently used in clinical practice are far from satisfactory, due to the specificity of the tumor microenvironment (TME). Identification of diagnostic and therapeutic reagents with strong contrast and therapeutic effect remains a great challenge. Herein, a novel carbon dot nanozyme (Mn-CD) is synthesized for the first time using toluidine blue (TB) and manganese as raw materials. As expected, the enhanced magnetic resonance (MR) imaging capability of Mn-CDs is realized in response to the TME (acidity and glutathione), and r1 and r2 relaxation rates are enhanced by 224% and 249%, respectively. In addition, the photostability of Mn-CDs is also improved, and show an efficient singlet oxygen (1 O2 ) yield of 1.68. Moreover, Mn-CDs can also perform high-efficiency peroxidase (POD)-like activity and catalyze hydrogen peroxide to hydroxyl radicals, which is greatly improved under the light condition. The results both in vitro and in vivo demonstrate that the Mn-CDs are able to achieve real-time MR imaging of TME responsiveness through aggregation of the enhanced permeability and retention effect at tumor sites and facilitate light-enhanced chemodynamic and photodynamic combination therapies. This work opens a new perspective in terms of the role of carbon nanomaterials in integrated diagnosis and treatment of diseases.

Recent developments in photodynamic therapy and its application against multidrug resistant cancers

Recently, photodynamic therapy (PDT) has received a lot of attention for its potential use in cancer treatment. It enables the therapy of a multifocal disease with the least amount of tissue damage. The most widely used prodrug is 5-aminolevulinic acid, which undergoes heme pathway conversion to protoporphyrin IX, which acts as a photosensitizer (PS). Additionally, hematoporphyrin, bacteriochlorin, and phthalocyanine are also studied for their therapeutic potential in cancer. Unfortunately, not every patient who receives PDT experiences a full recovery. Resistance to different anticancer treatments is commonly observed. A few of the resistance mechanisms by which cancer cells escape therapeutics are genetic factors, drug-drug interactions, impaired DNA repair pathways, mutations related to inhibition of apoptosis, epigenetic pathways, etc. Recently, much research has been conducted to develop a new generation of PS based on nanomaterials that could be used to overcome cancer cells' multidrug resistance (MDR). Various metal-based, polymeric, lipidic nanoparticles (NPs), dendrimers, etc, have been utilized in the PDT application against cancer. This article discusses the detailed mechanism by which cancer cells evolve towards MDR as well as recent advances in PDT-based NPs for use against multidrug-resistant cancers.

Facile preparation of toluidine blue-loaded DNA nanogels for anticancer photodynamic therapy

Photodynamic therapy (PDT) provides an effective therapeutic option for different types of cancer in addition to surgery, radiation, and chemotherapy. The treatment outcome of PDT is largely determined by both the light and dark toxicity of photosensitizers (PSs), which can be technically improved with the assistance of a drug delivery system, especially the nanocarriers. Toluidine blue (TB) is a representative PS that demonstrates high PDT efficacy; however, its application is largely limited by the associated dark toxicity. Inspired by TB's noncovalent binding with nucleic acids, in this study, we demonstrated that DNA nanogel (NG) could serve as an effective TB delivery vehicle to facilitate anticancer PDT. The DNA/TB NG was constructed by the simple self-assembly between TB and short DNA segments using cisplatin as a crosslinker. Compared with TB alone, DNA/TB NG displayed a controlled TB-releasing behavior, effective cellular uptake, and phototoxicity while reducing the dark toxicity in breast cancer cells MCF-7. This DNA/TB NG represented a promising strategy to improve TB-mediated PDT for cancer treatments.

[Natural melanin-based nanoparticles with photothermal/photodynamic activities induce ovarian cancer cell death]

OBJECTIVE

To investigate the physicochemical characteristics of natural melanin-like nanoparticles (PDA NPs) and their synergistic anti-tumor efficacy with photothermal and photodynamic (PTT/PDT) therapy.

METHODS

The chemically synthesized PDA NPs were characterized using transmission electron microscope (TEM), dynamic light scattering (DLS) and Zeta potential analysis, and their photothermal and photodynamic properties were assessed with near-infrared excitation light (NIR). The antitumor efficacy of free PDA or PDA combined with NIR irradiation (0.7 and 1.0 W/cm²) was evaluated in ovarian cancer cells using flow cytometry, Cell Counting Kit-8 (CCK-8), and Transwell assay and in a mouse model bearing subcutaneous ovarian cancer xenograft.

RESULTS

The synthesized PDA NPs showed a spherical morphology with diameters around 100 nm and a zeta potential of -20 mV. Upon NIR irradiation at 0.7 and 1.0 W/cm², the particles underwent temperature changes (ΔT) of about 15 and 30 ℃, respectively, and produced a large amount of singlet oxygen, demonstrating their excellent PTT/PDT properties. In ovarian cancer cells, treatment with PDA NPs alone did not induce obvious changes in reactive oxygen species (ROS) production or mitochondrial membrane potential (MTP), but when combined with NIR irradiation, these particles caused a significant increase of ROS and a reduction of MTP (P < 0.001), and such changes were more prominent with high power NIR (P < 0.01). PDA NPs alone showed no obvious cytotoxicity, but the combination of PDA with NIR irradiation produced potent killing effect on ovarian cancer cells (P < 0.001), and the effect was much stronger with a high power irradiation (P < 0.001). While PDA alone showed no inhibitory effect on tumor cell metastasis, the combined treatment with PDA and NIR irradiation, especially at a high power, significantly suppressed invasion and migration of ovarian cancer cells (P < 0.001). In the tumor-bearing mouse model, the combined treatment, but not PDA alone, produced a significant inhibitory effect on tumor growth (P < 0.001).

CONCLUSION

PDA NPs combined with NIR has a strong anti-tumor effect, suggesting a potential new therapeutic strategy for ovarian cancer.

Escherichia coli Mimetic Gold Nanorod-Mediated Photo- and Immunotherapy for Treating Cancer and Its Metastasis

Most cancer-related deaths are due to metastasis or recurrence. Therefore, the ultimate goal of cancer therapy will be to treat metastatic and recurrent cancers. Combination therapy for cancer will be one of trial for effective treating metastasis and recurrence. In this study, Escherichia coli-mimetic nanomaterials are synthesized using Escherichia coli membrane proteins, adhesion proteins, and gold nanorods, which are named E. coli mimetic AuNRs (ECA), for combination therapy against cancer and its recurrence. ECA treatment with 808 nm laser irradiation eliminates CT-26 or 4T1 tumors via a photothermal effect. ECA with laser irradiation induces activation of immune cells in the tumor-draining lymph nodes. The mice cured from CT-26 or 4T1 tumor by ECA are rechallenged with those cancer in the lung metastatic form, and the results showed that ECA treatment for the first CT-26 or 4T1 tumor challenge prevents cancer infiltration to the lung in the second challenge. This preventive effect of ECA against tumor growth in the second challenge is aided by cancer antigen-specific T cell immunity. Overall, these findings show that ECA is a nanomaterial with dual functions as a photothermal therapy for treating primary cancers and as immunotherapy for preventing recurrence and metastasis.

Recent Advancements in Mitochondria-Targeted Nanoparticle Drug Delivery for Cancer Therapy

Mitochondria are critical subcellular organelles that produce most of the adenosine triphosphate (ATP) as the energy source for most eukaryotic cells. Moreover, recent findings show that mitochondria are not only the "powerhouse" inside cells, but also excellent targets for inducing cell death via apoptosis that is mitochondria-centered. For several decades, cancer nanotherapeutics have been designed to specifically target mitochondria with several targeting moieties, and cause mitochondrial dysfunction via photodynamic, photothermal, or/and chemo therapies. These strategies have been shown to augment the killing of cancer cells in a tumor while reducing damage to its surrounding healthy tissues. Furthermore, mitochondria-targeting nanotechnologies have been demonstrated to be highly efficacious compared to non-mitochondria-targeting platforms both in vitro and in vivo for cancer therapies. Moreover, mitochondria-targeting nanotechnologies have been intelligently designed and tailored to the hypoxic and slightly acidic tumor microenvironment for improved cancer therapies. Collectively, mitochondria-targeting may be a promising strategy for the engineering of nanoparticles for drug delivery to combat cancer.