Hydrogen Sulfide Responsive Phototherapy Agents: Design Strategies and Biological Applications

Photo-Facilitated Nitric Oxide-Triggered Turn-on Photodynamic Therapy for Precise Antitumor Application

Photodynamic therapy (PDT) is a powerful strategy for tumor therapy with noninvasiveness and desirable efficacy. However, the phototoxicity of photosensitizer after the post-PDT is the major obstacle limiting the clinic applications. Herein, a nitric oxide (NO)-activatable photosensitizer is reported with turn-on PDT behavior and endoplasmic reticulum (ER) targeting ability for precise tumor therapy. Four o-thiophenediamine derivatives with reaction-tunable donor/acceptor push-pull electronic effect are established, and the systematic structure and property relationship observation reveals the following features: 1) the reactivity against NO can be improved by enhancing the electron density and further facilitated upon photo-irradiation. 2) the reactivity with NO enables the improved intramolecular charge transfer process with the evoking of photosensitizing effect. 3) only o-thiophenediamine derivative with ER enrichment behavior exhibited cancer cell ablation effect compared to photosensitizers localized in lysosome and lipid droplet. Thus, the efficient inhibition of cancer cells both in vitro and in vivo is realized based on the photo-controlled PDT strategy. This work provides more insights into developing promising activatable photosensitizers for advanced therapy based on tumor microenvironment trigger.

Unraveling the role of heavy metals xenobiotics in cancer: a critical review

Cancer is a multifaceted disease characterized by the gradual accumulation of genetic and epigenetic alterations within cells, leading to uncontrolled cell growth and invasive behavior. The intricate interplay between environmental factors, such as exposure to carcinogens, and the molecular cascades governing cell growth, differentiation, and survival contributes to cancer's development and progression. This review offers a comprehensive overview of key molecular targets and their roles in cancer development. Peroxisome proliferator-activated receptors are implicated in various cancers due to their role in regulating lipid metabolism, inflammation, and cell proliferation. Nuclear factor erythroid 2-related factor 2 protects cells from oxidative damage but can also promote tumor cell survival. Cytochrome P450 1B1 metabolizes exogenous and endogenous substances, and its increased expression is observed in several cancers. The constitutive androstane receptor regulates gene expression, and its dysregulation can lead to liver cancer. Transforming growth factor-beta 2 is involved in the development and progression of various cancers by dysregulating cell proliferation, differentiation, and migration. Chelation treatment has been investigated for removing heavy metals, while genetically altered immune cells show promise in treating specific cancers. Metal-organic frameworks and fibronectin targeting represent new directions in cancer treatment. While some heavy metals, such as arsenic, chromium, nickel, and cadmium, are known to have carcinogenic properties, others, like zinc, Copper, gold, bismuth, and silver, have many uses that highlight their potential as effective cancer control tactics. There are a variety of heavy metal-based technologies that show potential for improving cancer treatment methods, including targeted drug delivery, improved radiation, and diagnostic tools.

Glutathione-responsive biodegradable nanohybrid for cancer photoacoustic imaging and gas-assisted photothermal therapy

Photothermal therapy (PTT), particularly in the near-infrared-II (NIR-II) range, has attracted widespread attention over the past years. However, the accompanied inflammatory responses can result in undesirable side effects and contribute to treatment ineffectiveness. Herein, we introduced a novel biodegradable nanoplatform (CuS/HMON-PEG) capable of PTT and hydrogen sulfide (H2S) generation, aimed at modulating inflammation for improved cancer treatment outcomes. The embedded ultrasmall copper sulphide (CuS) nanodots (1-2 nm) possessed favorable photoacoustic imaging (PAI) and NIR-II photothermal capabilities, rendering CuS/HMON-PEG an ideal phototheranostic agent. Upon internalization by 4T1 cancer cells, the hollow mesoporous organosilica nanoparticle (HMON) component could react with the overproduced glutathione (GSH) to produce H2S. In addition to the anticipated photothermal tumor ablation and H2S-induced mitochondrial dysfunction, the anti-inflammatory regulation was also been demonstrated by the downregulation of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1beta (IL-1β). More importantly, the modulation of inflammation also promoted wound healing mediated by PTT. This work not only presents a H2S-based nanomodulator to boost NIR-II PTT but also provides insights into the construction of novel organic/inorganic hybrid nanosystems.

A mitochondria-targeted chemiluminescent probe for detection of hydrogen sulfide in cancer cells, human serum and in vivo

Hydrogen sulfide (H2S) as a critical messenger molecule plays vital roles in regular cell function. However, abnormal levels of H2S, especially mitochondrial H2S, are directly correlated with the formation of pathological states including neurodegenerative diseases, cardiovascular disorders, and cancer. Thus, monitoring fluxes of mitochondrial H2S concentrations both in vitro and in vivo with high selectivity and sensitivity is crucial. In this direction, herein we developed the first ever example of a mitochondria-targeted and H2S-responsive new generation 1,2-dioxetane-based chemiluminescent probe (MCH). Chemiluminescent probes offer unique advantages compared to conventional fluorophores as they do not require external light irradiation to emit light. MCH exhibited a dramatic turn-on response in its luminescence signal upon reacting with H2S with high selectivity. It was used to detect H2S activity in different biological systems ranging from cancerous cells to human serum and tumor-bearing mice. We anticipate that MCH will pave the way for development of new organelle-targeted chemiluminescence agents towards imaging of different analytes in various biological models.

A hydrogen sulfide and tyrosinase responsive dual-locked fluorophore for selective imaging of melanoma cells

A resorufin-based dual-locked fluorescent probe (RHT) was introduced to image melanoma cells selectively. RHT was shown to function as an AND molecular logic gate as it emitted a signal only in the presence of both hydrogen sulfide (H2S) and tyrosinase (Tyr), which are known to be overexpressed in melanoma cells. In vitro cell culture studies revealed that RHT can be activated with endogenous H2S and Tyr and allows selective imaging of B16-F10 cancer cells under confocal microscopy. RHT marks the first ever example of a fluorescent probe that is sequentially activated by H2S and Tyr.