Direct Readout Hypoxia Tumor Suppression In Vivo through NIR-Theranostic Activation

A near infrared fluorescent probe for hypoxia based on dicyanoisophorone and its application in Hela cells imaging

Hypoxia will accelerate tumors metastasis and deterioration, thereby limiting the effects of chemotherapy or radiotherapy. Thus, developing efficient techniques for detecting hypoxia in tumor cells is extremely important for cancer diagnosis and therapy. In this work, we reported a dicyanoisophorone-based probe (DCI-Azo) that specifically switched on its near infrared emission with hypoxia up-regulated azo-reductase (AzoR). In order to reduce the difficulty of synthesis and simplify the post-processing process, we adopted a one-pot-synthesis method to synthesized NIR fluorophore (DCI-Am) with yield 97 %. Based on the fluorophore, DCI-Azo was designed and synthesized. The sensitivity of DCI-Azo for hypoxia in vitro was evaluated with Na2S2O4 and rat liver microsomes. It exhibited near-infrared emission (λem = 650 nm), large Stokes Shift (>160 nm), high sensitivity (LOD 0.53 μg mL-1 rat liver microsomes), high selectivity, and low cytotoxicity (cell viability > 80 % after incubation for 24 h). Moreover, the probe was successfully used for detecting hypoxia (1% O2) in Hela cells and tumor tissue in mouse model. The fluorescence intensity in Hela cells has increased ∼ 26-fold when the oxygen level is reduced to 1 % from 21 % O2. The fluorescence intensity of the tumor area enhanced ∼ 5 folds compared to the normal area nearby. All these features demonstrated that the probe DCI-Azo was a versatile tool for in vivo assay and imaging for cancer diagnosis studies.

A NIR fluorescent probe based on tricyanofuran for the detection of β-galactosidase in living ovarian tumor cells and in vivo

β-Galactosidase (β-Gal) as an important glycoside hydrolase plays an important role in the early diagnosis of ovarian cancer. It is important to accurately and conveniently detect β-Gal in organisms. In this study, we developed a fluorescent probe TCF-GAL based on the tricyanofuran structure, which is linked to β-galactose through ether bonds for β-Gal detection. Probe TCF-GAL exhibited satisfactory selectivity and sensitivity toward β-Gal with the calculated LOD of 1.45 × 10-4 U/mL. Moreover, it can be applied to image endogenous β-Gal in living SKOV3 cells with low cytotoxicity. Importantly, probe TCF-GAL was successfully employed in monitoring β-Gal in the mouse subcutaneous model of ovarian cancer. These results indicated that this probe had great potential for diagnosing β-Gal related diseases.

A review on dendrimer-based nanoconjugates and their intracellular trafficking in cancer photodynamic therapy

Nanotechnology-based cancer treatment has received considerable attention, and these treatments generally use drug-loaded nanoparticles (NPs) to target and destroy cancer cells. Nanotechnology combined with photodynamic therapy (PDT) has demonstrated positive outcomes in cancer therapy. Combining nanotechnology and PDT is effective in targeting metastatic cancer cells. Nanotechnology can also increase the effectiveness of PDT by targeting cells at a molecular level. Dendrimer-based nanoconjugates (DBNs) are highly stable and biocompatible, making them suitable for drug delivery applications. Moreover, the hyperbranched structures in DBNs have the capacity to load hydrophobic compounds, such as photosensitizers (PSs) and chemotherapy drugs, and deliver them efficiently to tumour cells. This review primarily focuses on DBNs and their potential applications in cancer treatment. We discuss the chemical design, mechanism of action, and targeting efficiency of DBNs in tumour metastasis, intracellular trafficking in cancer treatment, and DBNs' biocompatibility, biodegradability and clearance properties. Overall, this study will provide the most recent insights into the application of DBNs and PDT in cancer therapy.

A Photoinduced Electron Transfer-Based Hypochlorite-Specific Fluorescent Probe for Selective Imaging of Proinflammatory M1 in a Rheumatoid Arthritis Model

The differentiation of the distinct phenotypes of macrophages is essential for monitoring the stage of inflammatory diseases for accurate diagnosis and treatment. Recent studies revealed that the level of hypochlorite (OCl^-) varies from activated M1 macrophages (killing pathogens) to M2 (resolution of inflammation) during inflammation. Thus, we developed a simple and efficient fluorescent probe for discriminating M1 from M0 and M2. Herein, fluorescent-based imaging is applied as an alternative to immunohistochemistry, which is challenging due to the tedious process and high cost. We developed a hypochlorite-specific probe PMS-T to differentiate M1 and M2, employing a metabolism-oriented live-cell distinction. This probe enables the detection of inflammatory rheumatoid arthritis in an ex vivo mouse model. Thus, it can be a potential chemical tool for monitoring inflammatory diseases, including rheumatoid arthritis, that may overcome the existing barriers of immunohistochemistry.

An efficient PeT based fluorescent probe for mapping mitochondrial oxidative stress produced via the Nox2 pathway

The human innate immune system eliminates invading pathogens through phagocytosis. The first step of this process is activating the nicotinamide adenine dinucleotide phosphate oxidase (Nox2) that utilizes NADPH to produce superoxide anion radicals and other reactive oxygen species (ROS). These ROS then alter the mitochondrial membrane potential and increase peroxide in the mitochondria. The peroxide reacts with myeloperoxidase (MPO) and chloride ions to produce pro-inflammatory oxidant hypochlorous acid (HOCl), which causes oxidative stress leading to cell death. The adverse effects of HOCl are highly associated with cardiovascular disease, neurodegenerative disorders, acute lung injuries, inflammatory diseases, and cancer. Therefore, mapping HOCl in the Nox2 pathway is crucial for an in-depth understanding of the innate immune system. Herein, we developed a unique pentacyclic pyridinium probe, PM-S, that exhibited efficient photoinduced electron transfer (PeT) with HOCl triggered methyl(phenyl)sulfane. PM-S showed several advantages, including better chemical stability, large Stokes shifts (>6258 cm^-1), high sensitivity (∼50 nM) and specificity to mitochondria, compared to its parent pyrylium PY-S derivative. This probe is also efficient in studying the HOCl produced via the Nox2 pathway in HepG2 and HeLa cells. Analysis using a simple microplate reader and FACS analysis with various inhibitors and inducers supported the mechanistic understanding of Nox2, which can offer an advanced platform for monitoring the inflammatory process more efficiently.

Construction of synergistic pH/H2O2-responsive prodrug for prolonging blood circulation and accelerating cellular internalization

We have developed a real-time and multifunctional doxifluridine-conjugate prodrug (LYX), which involved the preliminary methylfluorescein with 5-fluorouracil linker as protecting group, the targeting biotin unit, and a model therapeutic drug (doxifluridine). The shielding group (5'-DFUR) was found to be effective in prolonging circulation at physiological pH 7.4 and improving accumulation in the acidic microenvironment of the tumor. Based on this strategy, the stability and stimulus responsive properties of prodrug could enhance drug release efficiency and exhibit fewer side effects, thereby providing a unique opportunity for diagnosis and imaging additional analytes or enzymatic activities.