Biomimetic Cascade Polymer Nanoreactors for Starvation and Photodynamic Cancer Therapy.

The selective disruption of nutritional supplements and the metabolic routes of cancer cells offer a promising opportunity for more efficient cancer therapeutics. Herein, a biomimetic cascade polymer nanoreactor (GOx/CAT-NC) was fabricated by encapsulating glucose oxidase (GOx) and catalase (CAT) in a porphyrin polymer nanocapsule for combined starvation and photodynamic anticancer therapy. Internalized by cancer cells, the GOx/CAT-NCs facilitate microenvironmental oxidation by catalyzing endogenous H2O2 to form O2, thereby accelerating intracellular glucose catabolism and enhancing cytotoxic singlet oxygen (1O2) production with infrared irradiation. The GOx/CAT-NCs have demonstrated synergistic advantages in long-term starvation therapy and powerful photodynamic therapy (PDT) in cancer treatment, which inhibits tumor cells at more than twice the rate of starvation therapy alone. The biomimetic polymer nanoreactor will further contribute to the advancement of complementary modes of spatiotemporal control of cancer therapy.

Natural photosensitizers from Tripterygium wilfordii and their antimicrobial photodynamic therapeutic effects in a Caenorhabditis elegans model.

Tripterygium wilfordii Hook. f. is a traditional medicinal plant and has long been used in East Asia to treat many diseases. However, the extract and active components have never been investigated as potential photosensitizers for photodynamic treatment to kill pathogenic microorganisms. Here, the antimicrobial photodynamic treatment (APDT) effects of the extract, fractions, and compounds of T. wilfordii were evaluated in vitro and in vivo. Ethanolic extract (TWE) and the photosensitizer-enriched fraction (TW-F5) were prepared from dried T. wilfordii. Six active compounds were isolated from TW-F5 by semipreparative high-performance liquid chromatography, and their chemical structures were characterized through spectroscopic and spectrometric analysis. The singlet oxygen from extracts, fractions, and compounds was measured by using the imidazole-N,N-dimethyl-4-nitrosoaniline method. These extracts, fractions, and compounds were used as photosensitizers for the inactivation of bacteria and fungi by red light at 660 nm. The in vitro APDT effects were also evaluated in the model animal Caenorhabditis elegans. APDT with TWE showed effective antimicrobial activity against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and Candida albicans. TW-F5, consisting of six pheophorbide compounds, also showed strong APDT activity. The photosensitizers were taken up into the bacterial cells and induced intracellular ROS production by APDT. TWE and TW-F5 also induced a strong APDT effect in vitro against skin pathogens, including Staphylococcus epidermidis and Streptococcus pyogenes. We evaluated the APDT effects of TWE and TW-F5 in C. elegans infected with various pathogens and found that PDT effectively controlled pathogenic bacteria without strong side effects. APDT reversed the growth retardation of worms induced by pathogen infection and decreased the viable pathogenic bacterial numbers associated with C. elegans. Finally, APDT with TWE increased the survivability of C. elegans infected with S. pyogenes. In summary, TWE and TW-F5 were found to be effective antimicrobial photosensitizers in PDT.

Singlet oxygen in Escherichia coli: New insights for antimicrobial photodynamic therapy.

Antimicrobial photodynamic therapy is an emerging treatment for bacterial infections that is becoming increasingly more attractive because of its effectiveness and unlikelihood of inducing bacterial resistance. However, there is limited knowledge about the localization of the photoactive drug in the bacteria and about the details of production of the main cytotoxic species, singlet oxygen. This article describes a combination of spectroscopic and time-resolved photophysical techniques that provide such information for a cationic porphyrin photosensitizer in gram-negative Escherichia coli bacteria. Our results reveal a double localization of the photosensitizer, inside (bound to the nucleic acids) and outside (bound to the cell wall) of the E. coli cells. Singlet oxygen is produced at both sites and is able to cross the cell wall.

A general system for evaluating the efficiency of chromophore-assisted light inactivation (CALI) of proteins reveals Ru(II) tris-bipyridyl as an unusually efficient "warhead".

Chromophore-assisted light inactivation (CALI) of proteins is a potentially powerful tool in biological research for the triggered disruption of protein function. It involves the creation of chimeric molecules that can bind specifically to the protein target and can also sensitize the photo-generation of singlet oxygen, which inactivates the target protein. There remains a need for more efficient chromophores for singlet oxygen generation. Here we report a general and convenient system with which to evaluate the efficiency of chromophores in CALI both in crude extracts and in living cells. We employ this system to show that a readily available derivative of ruthenium(II) tris-bipyridyl dication is an unusually efficient "warhead" for CALI, exhibiting a performance markedly superior to the commonly used organic fluorophore, fluorescein.

Fungal elicitor induces singlet oxygen generation, ethylene release and saponin synthesis in cultured cells of Panax ginseng C. A. Meyer.

Singlet oxygen is a high-energy molecular oxygen species. As one of the most active intermediates involved in chemical and biochemical reactions, singlet oxygen plays essential roles in plant responses to UV and strong light. Here, we report that Cle, an elicitor derived from fungal cell walls, induces the generation of singlet oxygen in cell cultures of ginseng, Panax ginseng. Cle treatment also triggers the activation of plasma membrane NADPH oxidase and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO), subsequently leading to ethylene release and increased saponin synthesis, as shown by increased mRNA expression of squalene synthase (SQS) and squalene epoxidase (SQE), and accumulation of beta-amyrin synthase (beta-AS). Suppression of Cle-induced singlet oxygen generation or inhibition of ethylene production blocks saponin synthesis, whereas treatment of ginseng cells with ethylene or singlet oxygen induces the synthesis of saponin. Together, these results indicate that Cle-induced production of both singlet oxygen and ethylene is required for saponin synthesis, and that singlet oxygen may function upstream of ethylene during Cle-induced saponin synthesis.