Biological applications of nanoparticles are rapidly increasing, which introduces new possibilities to improve the efficacy of radiotherapy. Here, we synthesized titanium peroxide nanoparticles (TiOxNPs) and investigated their efficacy as novel agents that can potently enhance the effects of radiation in the treatment of pancreatic cancer. TiOxNPs and polyacrylic acid-modified TiOxNPs (PAA-TiOxNPs) were synthesized from anatase-type titanium dioxide nanoparticles (TiO2NPs). The size and morphology of the PAA-TiOxNPs was evaluated using transmission electron microscopy and dynamic light scattering. The crystalline structures of the TiO2NPs and PAA-TiOxNPs with and without X-ray irradiation were analyzed using X-ray absorption. The ability of TiOxNPs and PAA-TiOxNPs to produce reactive oxygen species in response to X-ray irradiation was evaluated in a cell-free system and confirmed by flow cytometric analysis in vitro. DNA damage after X-ray exposure with or without PAA-TiOxNPs was assessed by immunohistochemical analysis of γ-H2AX foci formation in vitro and in vivo. Cytotoxicity was evaluated by a colony forming assay in vitro. Xenografts were prepared using human pancreatic cancer MIAPaCa-2 cells and used to evaluate the inhibition of tumor growth caused by X-ray exposure, PAA-TiOxNPs, and the combination of the two. The core structures of the PAA-TiOxNPs were found to be of the anatase type. The TiOxNPs and PAA-TiOxNPs showed a distinct ability to produce hydroxyl radicals in response to X-ray irradiation in a dose- and concentration-dependent manner, whereas the TiO2NPs did not. At the highest concentration of TiOxNPs, the amount of hydroxyl radicals increased by >8.5-fold following treatment with 30 Gy of radiation. The absorption of PAA-TiOxNPs enhanced DNA damage and resulted in higher cytotoxicity in response to X-ray irradiation in vitro. The combination of the PAA-TiOxNPs and X-ray irradiation induced significantly stronger tumor growth inhibition compared to treatment with either PAA-TiOxNPs or X-ray alone (p < 0.05). No apparent toxicity or weight loss was observed for 43 days after irradiation. TiOxNPs are potential agents for enhancing the effects of radiation on pancreatic cancer and act via hydroxyl radical production; owing to this ability, they can be used for pancreatic cancer therapy in the future.

Xylitol is a major commodity chemical widely used in both the food and pharmaceutical industries. Although the worldwide demand for xylitol is constantly growing, its industrial production from purified D-xylose involves a costly and polluting catalytic hydrogenation process. Biotechnological production of xylitol from biomass is a promising strategy to establish an environmentally friendly sustainable conversion process. In this study, xylitol was produced from woody Kraft pulp (KP) by using an engineered strain of Saccharomyces cerevisiae (YPH499-XR-BGL-XYL-XYN) expressing cytosolic xylose reductase (XR), along with β-D-glucosidase (BGL), xylosidase (XYL) and xylanase (XYN) enzymes co-displayed on the cell surface. All these enzymes contributed to the consolidated bioprocessing of KP to xylitol with a yield of 2.3 g L⁻¹ (28% conversion) after 96 hours, along with a significantly reduced amount of commercial enzymes required for pre-treatment (commercial hemicellulase cocktail (CHC), [CHC] = 0.02 g-DW per g). Further improvement of the cell surface display of XYL and XYN was obtained by using a SED1 “SSS” cassette, containing the coding sequences of the SED1 promoter, the SED1 secretion signal, and the SED1 anchoring domain, to generate the improved strain YPH499-XR-BGL-XYLsss-XYNsss. This improved strain showed a significantly enhanced xylitol production capacity reaching a yield of 3.7 g L⁻¹ (44% conversion) after 96 hours. The cellulosic content of KP residues was also significantly increased, from 78% to 87% after 96 hours of fermentation, and nanofibrillation of KP residues was observed by scanning electron microscopy. Pre-treatment and fermentation were successfully performed as a proof of concept to further scale up bio-refinery industrial production of xylitol from lignocellulose.

The development of potentially safe radiosensitizing agents is essential to enhance the treatment outcomes of radioresistant cancers. The titanium peroxide nanoparticle (TiOxNP) was originally produced using the titanium dioxide nanoparticle, and it showed excellent reactive oxygen species (ROS) generation in response to ionizing radiation. Surface coating the TiOxNPs with polyacrylic acid (PAA) showed low toxicity to the living body and excellent radiosensitizing effect on cancer cells. Herein, we evaluated the mechanism of radiosensitization by PAA-TiOxNPs in comparison with gold nanoparticles (AuNPs) which represent high-atomic-number nanoparticles that show a radiosensitizing effect through the emission of secondary electrons. The anticancer effects of both nanoparticles were compared by induction of apoptosis, colony-forming assay, and the inhibition of tumor growth. PAA-TiOxNPs showed a significantly more radiosensitizing effect than that of AuNPs. A comparison of the types and amounts of ROS generated showed that hydrogen peroxide generation by PAA-TiOxNPs was the major factor that contributed to the nanoparticle radiosensitization. Importantly, PAA-TiOxNPs were generally nontoxic to healthy mice and caused no histological abnormalities in the liver, kidney, lung, and heart tissues.

Bionanocapsule (BNC) is hollow nanoparticle composed of the l-protein of the hepatitis B virus surface antigen. BNC allows targeted delivery of either genes or drugs only to hepatocytes, but not to other cell types. In this study, we attempted to alter the specificity of BNC by insertion of biotin-acceptor peptide (BAP), which is efficiently biotinylated using biotin ligase BirA from Escherichia coli. Using streptavidin as a linker, biotinylated BNC could be display various biotinylated ligands that are otherwise difficult to fuse with BNC, such as antibodies, synthetic peptides and functional molecules. BAP-fused BNC was efficiently biotinylated and effectively displayed streptavidin. Furthermore, we demonstrated that biotinylated BNC was internalized into targeted cells via biotinylated Nanobody displayed on the BNC surface. Biotinylated BNC permit display of diverse ligands, and thus have potential as a versatile carrier for drug delivery to a variety of target cells.