Hydrogen Sulfide Delivery System Based on Salting-Out Effect for Enhancing Synergistic Photothermal and Photodynamic Cancer Therapies

The simultaneous application of photothermal therapy (PTT) and photodynamic therapy (PDT) offers substantial advantages in cancer treatment. However, their synergistic anticancer efficacy is often limited by tumor hypoxia, and thermotolerance induced by high expression of heat shock proteins (HSP). Fortunately, hydrogen sulfide (H2S), known for its direct cytotoxic effect on tumor cells, has been recognized for its ability to enhance PTT and PDT. The effectiveness of H2S in these therapies is challenged by its low loading efficiency, poor stability, and short diffusion distance. To address these issues, a nanoscale emulsion drop template created through the salting-out effect is employed to construct a robust H2S delivery system. Polydopamine (PDA), chosen for its interfacial polymerization tendency and excellent photothermal conversion rate, is utilized as a carrier for the H2S donor (ADT) and Zinc phthalocyanine (ZnPc) to fabricate a novel nanomedicine termed APZ NPs. The temperature-responsive APZ NPs are designed to release H2S during the PTT process. Elevated H2S levels promoted vasodilation, thereby enhancing the enhanced permeability and retention effect (EPR) of APZ NPs within solid tumors. This strategy effectively alleviated tumor hypoxia by disrupting the mitochondrial respiratory chain and mitigated tumor cell heat tolerance by inhibiting HSP expression.

Drug Self-delivery Nanorods Enhance Photodynamic Therapy of Triple-Negative Breast Cancer by inhibiting Oxidative Phosphorylation

Photodynamic therapy (PDT) shows very high potential for the clinical treatment of triple-negative breast cancer. However, the efficacy of PDT is significantly weakened by tumor hypoxia, the relatively high intracellular glutathione levels and the active proliferation of cancer cells. To address these issues, we developed a novel drug self-delivery nanorod (defined as AINRs) through the hydrophobic interaction among the mitochondrial complex III inhibitor (atovaquone, ATO), the photosensitizer (indocyanine green, ICG) and the dispersion stabilizer (distearoyl phosphoethanolamine-polyethylene glycol 2000, DSPE-PEG 2000). The AINRs showed a rod-like morphology with a mean diameter of 120.6 ± 5.4 nm, a zeta potential of -26.35 ± 1.63 mV and a significantly high drug loading rate of 93.48%. The results of in vitro cell experiments involving triple-negative breast cancer cell lines (4T1 cells and MDA-MB-231 cells) indicated that the AINRs could effectively block the oxidative phosphorylation of cancer cells through the inhibition of mitochondrial complex III, which results in the reduction of endogenous oxygen consumption and the decrease of the intracellular ATP level. The reduction of ATP content further inhibited the glutathione synthesis and arrested the cell cycle at the S-phase, which results in enhanced in vitro PDT efficacy of ICG. The results of in vivo antitumor activity in 4T1-bearing mice showed that the tumor growth inhibition rate of the AINRs with near-infrared laser irradiation (NIR) was 90%, whereas the tumor growth inhibition rates of the AINRs without NIR, ICG with NIR and doxorubicin (3 mg/kg) were only 31.68%, 61.15% and 24.59%, respectively. In addition, the results of safety studies, including body weights, biochemical indicators and H&E staining images of the main organs demonstrated the security of the AINRs. In summary, this study showed that the oxidative phosphorylation inhibition of triple-negative breast cancer was a safe and effective method to enhance its PDT efficacy.

Coconut-shell-derived activated carbon for NIR photo-activated synergistic photothermal-chemodynamic cancer therapy

Exploiting new non-metal-based peroxidase-mimic nanoenzymes for chemodynamic therapy (CDT) in cancer treatment is an active and challenging field. Here, we found that activated carbon nanoparticles (denoted as ANs) fabricated from coconut shell have satisfactory peroxidase-mimic nanoenzyme activity. Based on this positive result, gadodiamide, a clinically used nuclear magnetic imaging contrast agent, was loaded inside the AN pores and encapsulated by polyvinylpyrrolidone (PVP) to obtain Gd@PANs. PANs (ANs modified using PVP) efficiently catalyze the massive decomposition of endogenous hydrogen peroxide (H2O2) inside cancer cells to produce toxic oxidized hydroxyl radicals (˙OH) for the CDT treatment of cancer, but they showed no toxicity toward normal cells. Additionally, under 808 nm laser irradiation, the photothermal conversion efficiency of the PANs reaches 45.20%, ensuring their effective photothermal therapy (PTT) treatment functionality. Simultaneously, during PTT treatment, the heating effect significantly enhances the peroxidase-mimic activity of the PANs to achieve an ideal PTT-CDT synergistic therapeutic outcome. Gd@PANs can also be used for the T1-magnetic resonance imaging (MRI) of tumors to integrate treatment and diagnosis.

Physical Insights into Molecular Sensors, Molecular Logic Gates, and Photosensitizers in Photodynamic Therapy

In this article, the importance of charge/electron transfer in two rapidly growing areas of science is highlighted. In the field of molecular sensors, it plays a considerable role on the detection of molecular systems to serve as fluorescence sensors, switches, and molecular logic gates (MLG) replacing the semiconductor electronics, while in the field of photodynamic therapy, it acts competitive. On these scientific fields, a lot of research has been conducted in the last decades to find out potential candidates. In the field of fluorescent sensors, switches, and molecular logic gates, the fluorescent photo-induced electron transfer switching principle is responsible for the quenching of fluorescence. The manipulation of the quenching can lead to the design of an ideal candidate for complicated molecular logic operation. In the field of photodynamic therapy (PDT), the intersystem crossings occurring between excited singlet and triplet states are the key for an ideal photosensitizer (PS) candidate. The triplets must present relatively long lifetimes, and they must lie near or above the energy which is needed for the excitation of molecular oxygen. It this case, charge/electron phenomena can act competitive, and they are not desirable. However, there are a few complexes which are good PSs of singlet oxygen despite the charge transfer (CT) nature of their lowest excited state.

Drug-Controlled Release Based on Complementary Base Pairing Rules for Photodynamic-Photothermal Synergistic Tumor Treatment

Controlled drug release systems can enhance the safety and availability but avoid the side effect of drugs. Herein, the concept of DNA complementary base pairing rules in biology is used to design and prepare a photothermal-triggered drug release system. Adenine (A) modified polydopamine nanoparticles (A-PDA, photothermal reagent) can effectively bind with thymine (T) modified Zinc phthalocyanine (T-ZnPc, photosensitizer) forming A-PDA = T-ZnPc (PATP) complex based on A = T complementary base pairing rules. Similar to DNA, whose base pairing in double strands will break by heating, T-ZnPc can be effectively released from A-PDA after near infrared irradiation-triggered light-thermal conversion to obtain satisfactory photodynamic-photothermal synergistic tumor treatment. In addition, PDA can carry abundant Gd³⁺ to provide magnetic resonance imaging guided delivery and theranostic function.

Pre-drug Self-assembled Nanoparticles: Recovering activity and overcoming glutathione-associated cell antioxidant resistance against photodynamic therapy

In photodynamic therapy (PDT), the elevated glutathione (GSH) of cancer cells have two sides for treatment efficacy, activation pre-drug by removing activity suppressor part (advantages) and consumption reactive oxygen species (ROS) to confer PDT resistance (disadvantages). Preparation all-in-one system by simple method to make best use of the advantages and bypass the disadvantages still were remains a technical challenge. Herein, we report a robust PDT nanoparticle with above function based on a self-assembled pyridine modified Zinc phthalocyanine (ZnPc-DTP). The activity suppressor and active part of ZnPc-DTP were linked by disulfide bond. After targeting cancer cells, GSH can react with ZnPc-DTP nanoparticles by cutting disulfide bond to release its active part (ZnPc-SH) and oxidize GSH. In vitro and in vivo results indicated that ZnPc-SH can effective suppress tumor growth under the low antioxidant tumor microenvironment (TME).

A smart copper-phthalocyanine framework nanoparticle for enhancing photodynamic therapy in hypoxic conditions by weakening cells through ATP depletion

Hypoxic tumor treatment by synergistic of photodynamic therapy and ATP deprivation.

Mercaptopyrimidine-directed gold nanoclusters: a suitable fluorescent probe for intracellular glutathione imaging and selective cancer cell identification

Herein, we demonstrate a novel, facile, and suitable strategy for imaging GSH based on mercaptopyrimidine-directed gold nanoclusters (Au NCs).