As the implications of reactive oxygen species (ROS) are elucidated in many diseases, ROS-responsive nanoparticles are attracting great interest from researchers. In this work, a ROS sensitive thioketal (TK) moiety with a π-conjugated structure was introduced into biodegradable methoxy poly(ethylene glycol)-thioketal-poly(ε-caprolactone)mPEG-TK-PCL micelles as a linker, which was designed to speed up the drug release and thus enhance the therapeutic efficacy. The micelle showed a high drug loading content of 12.8% and excellent stability under physiological conditions because of the evocation of π–π stacking and hydrophobic interactions with the anticancer drug doxorubicin (DOX). The polymeric micelle presented a better drug carrier capacity and higher in vitro anticancer efficacy towards cancer cells. The in vivo study showed that DOX-loaded mPEG-TK-PCL micelles displayed lower toxicity towards normal cells and remarkably enhanced antitumor efficacy. This research provides a way to design potential drug carriers for efficient cancer chemotherapy.

Low molecular weight gels (LMWGs) have significant advantages in drug delivery such as high drug loading capacity, in situ delivery of drug to the lesion site, sustaining drug release with excellent bioavailability, and minimized side effects. Here, we synthesized a reactive oxygen species (ROS)-responsive gelator to prepare an injectable gel. An anticancer drug, doxorubicin hydrochloride (DOX), and a photosensitizer, Zn(II) phthalocyanine tetrasulfonic acid (ZnPCS₄), were loaded into the gel for combined chemo-photodynamic therapy. The ROS-responsive gelator was characterized by proton nuclear magnetic resonance (¹H NMR) and the morphology of gels was investigated by scanning electron microscopy (SEM). The rheological properties and destruction–recovery capability of both blank and drug-loaded gels were studied. The cytotoxicity of LMWGs against 3T3 fibroblasts and 4T1 breast cancer cells was tested. The in vitro drug release of both drugs was studied and the in vivo anticancer activities of DOX–ZnPCS₄-coloaded LMWGs were investigated in tumor-bearing mice. The results revealed that the injectable ROS-responsive DOX–ZnPCS₄-coloaded LMWGs exhibited excellent anti-tumor efficacy by a synergistic therapy.

Malignant melanoma is the most fatal form of skin cancer worldwide, and earlier diagnosis and more effective therapies are required to improve prognosis. As a possible solution, near-infrared fluorescent heptamethine cyanine dyes have been shown to be useful for tumor diagnosis and treatment. Here, we synthesized a novel theranostic agent, IR-817, a multifunctional bioactive small-molecule that has near-infrared emission, targets mitochondria in cancer cells, and has selective anti-cancer effects. In in vitro experiments, IR-817 preferentially accumulated in melanoma cells through organic anion transporting polypeptide transporters but also selectively inhibited the growth of tumor cells by inducing mitochondrial-dependent intrinsic apoptosis. Mechanistically, IR-817 caused G0/G1 cell cycle arrest by targeting the E2F/Cyclin/CDK pathway. Finally, IR-817 significantly suppressed the growth of xenograft tumors in zebrafish and mice. Immunohistochemical staining and hematoxylin and eosin staining revealed that IR-817 induced apoptosis and inhibited tumor cell proliferation without notable side effects. Therefore, mitochondrial-targeting theranostic agent IR-817 may be promising for accurate tumor diagnosis, real-time monitoring, and safe anti-cancer treatments.

Background: Near-infrared cyanine dyes have high sensitivity and spatial resolution imaging capabilities, but they also have unavoidable drawbacks such as photobleaching, low water solubility, fluorescence quenching, and toxic side effects. As an effective biologic drug carrier, albumin combines with cyanine dyes to form albumin@dye nanoparticles. These nanoparticles can alleviate the aforementioned issues and are widely used in tumor imaging and photothermal therapy. Methods: Herein, a newly synthesized near-infrared dye IR-817 was combined with bovine serum albumin (BSA) to create BSA@IR-817 nanoparticles. Through the detection of fluorescence emission and absorption, the optimal concentration and ratio of BSA and IR-817 were determined. Subsequently, dynamic light scattering (DLS) measurements and scanning electron microscopy (SEM) were used for the physical characterization of the BSA@IR-817 nanoparticles. Finally, in vitro and in vivo experiments were conducted to assess the fluorescence imaging and photothermal therapeutic potential of BSA@IR-817 nanoparticles. Results: IR-817 was adsorbed onto the BSA carrier by covalent conjugation and supramolecular encapsulation, resulting in the formation of dispersed, homogeneous, and stable nanoparticles with a particle size range of 120-220 nm. BSA@IR-817 not only improved the poor water solubility, fluorescence quenching, and toxic side effects of IR-817 but also enhanced the absorption and fluorescence emission peaks in the near-infrared region, as well as the fluorescence in the visible spectrum. In addition, BSA@IR-817 combined with laser 808 irradiation was able to convert light energy into heat energy with temperatures exceeding 50 degrees C. By creating a mouse model of subcutaneous melanoma, it was discovered that the tumor inhibition rate of BSA@IR-817 was greater than 99% after laser irradiation and that it achieved nearly complete tumor ablation without causing significant toxicity. Conclusion: Our research, therefore, proposes the use of safe and effective photothermal nanoparticles for the imaging, diagnosis, and treatment of melanoma, and offers a promising strategy for future biomedical applications.

Toad venom, a dried product of secretion from Bufo bufo gargarizans Cantor or Bufo melanostictus Schneider, has had the therapeutic effects of hepatocellular carcinoma confirmed. Bufalin and cinobufagin were considered as the two most representative antitumor active components in toad venom. However, the underlying mechanisms of this antitumor effect have not been fully implemented, especially the changes in endogenous small molecules after treatment. Therefore, this study was designed to explore the intrinsic mechanism on hepatocellular carcinoma after the cotreatment of bufalin and cinobufagin based on untargeted tumor metabolomics. Ultraperformance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) was performed to identify the absorbed components of toad venom in rat plasma. In vitro experiments were determined to evaluate the therapeutic effects of bufalin and cinobufagin and screen the optimal ratio between them. An in vivo HepG2 tumor-bearing nude mice model was established, and a series of pharmacodynamic indicators were determined, including the body weight of mice, tumor volume, tumor weight, and histopathological examination of tumor. Further, the entire metabolic alterations in tumor after treating with bufalin and cinobufagin were also profiled by UHPLC-MS/MS. Twenty-seven active components from toad venom were absorbed in rat plasma. We found that the cotreatment of bufalin and cinobufagin exerted significant antitumor effects both in vitro and in vivo, which were reflected in inhibiting proliferation and inducing apoptosis of HepG2 cells and thereby causing cell necrosis. After cotherapy of bufalin and cinobufagin for twenty days, compared with the normal group, fifty-six endogenous metabolites were obviously changed on HepG2 tumor-bearing nude mice. Meanwhile, the abundance of α-linolenic acid and phenethylamine after the bufalin and cinobufagin intervention was significantly upregulated, which involved phenylalanine metabolism and α-linolenic acid metabolism. Furthermore, we noticed that amino acid metabolites were also altered in HepG2 tumor after drug intervention, such as norvaline and Leu-Ala. Taken together, the cotreatment of bufalin and cinobufagin has significant antitumor effects on HepG2 tumor-bearing nude mice. Our work demonstrated that the in-depth mechanism of antitumor activity was mainly through the regulation of phenylalanine metabolism and α-Linolenic acid metabolism.