Quinoxalineimide-Based Semiconducting Polymer Nanoparticles as an Effective Phototheranostic for the Second Near-Infrared Fluorescence Imaging and Photothermal Therapy.

Multifunctional theranostics play a critical role in improving the efficacy of photothermal therapy and tumor fluorescence imaging; however, they require the integration of complex components into a single theranostic system, and their response in the second near-infrared (NIR-II) region is constrained by wavelengths of a photosensitizer. To address this issue, we herein developed a novel multifunctional thiazole-fused quinoxalineimide semiconducting polymer (named PQIA-BDTT), which exhibits NIR-II fluorescence and photothermal properties. PQIA-BDTT nanoparticles achieved an impressively high photothermal conversion efficiency (72.6%) in laser (1064 nm)-induced photothermal therapy at a safe maximum permissible exposure, demonstrating their capability as an effective photothermal agent. Moreover, PQIA-BDTT nanoparticles can be used as a reference for NIR-II fluorescence imaging under a low laser fluence. The tumor size and location in 4T1 mice intravenously injected with the PQIA-BDTT nanoparticles could be precisely identified through NIR-II fluorescence imaging, which also exhibited remarkable photothermal antitumor efficacy by in vitro and in vivo therapy. Overall, this study demonstrates that introducing a thiazole-fused quinoxalineimide acceptor unit into a donor-acceptor conjugated polymer is an effective strategy for the synthesis of novel multifunctional theranostic systems, which provides a novel platform for designing theranostic agents for biomedical applications.

Transcriptome-guided gene isolation and functional characterization of UDP-xylose synthase and UDP-D-apiose/UDP-D-xylose synthase families from Ornithogalum caudatum Ait.

KEY MESSAGE: The present study first identified the involvement of OcUAXS2 and OcUXS1-3 in anticancer polysaccharides biosynthesis in O. caudatum. UDP-xylose synthase (UXS) and UDP-D-apiose/UDP-D-xylose synthase (UAXS), both capable of converting UDP-D-glucuronic acid to UDP-D-xylose, are believed to transfer xylosyl residue to anticancer polysaccharides biosynthesis in Ornithogalum caudatum Ait. However, the cDNA isolation and functional characterization of genes encoding the two enzymes from O. caudatum has never been documented. Previously, the transcriptome sequencing of O. caudatum was performed in our laboratory. In this study, a total of six and two unigenes encoding UXS and UAXS were first retrieved based on RNA-Seq data. The eight putative genes were then successfully isolated from transcriptome of O. caudatum by reverse transcription polymerase chain reaction (RT-PCR). Phylogenetic analysis revealed the six putative UXS isoforms can be classified into three types, one soluble and two distinct putative membrane-bound. Moreover, the two UAXS isoenzymes were predicted to be soluble forms. Subsequently, these candidate cDNAs were characterized to be bona fide genes by functional expression in Escherichia coli individually. Although UXS and UAXS catalyzed the same reaction, their biochemical properties varied significantly. It is worth noting that a ratio switch of UDP-D-xylose/UDP-D-apiose for UAXS was established, which is assumed to be helpful for its biotechnological application. Furthermore, a series of mutants were generated to test the function of NAD+ binding motif GxxGxxG. Most importantly, the present study determined the involvement of OcUAXS2 and OcUXS1-3 in xylose-containing polysaccharides biosynthesis in O. caudatum. These data provide a comprehensive knowledge for UXS and UAXS families in plants.