Semiconducting Polymers Based on Asymmetric Thiadiazoloquinoxaline for Augmented In Vivo NIR-II Photoacoustic Imaging.

A photoacoustic (PA) imaging technique using the second near-infrared (NIR-II) window has attracted more and more attention because of its merits of deeper penetration depth and higher signal-to-noise (S/N) ratio than that using the first near-infrared (NIR-I) one. However, the design and development of high-performance PA imaging contrast agents in the NIR-II window is still a challenge. A semiconducting polymer, constructed by asymmetric units, exhibits regiorandom characteristics that effectively increase the distortion of the backbone. This increase in the degree of twist can regulate the twisted intramolecular charge transfer (TICT) effect, resulting in an enhancement of the PA signal. In this paper, an asymmetric structural acceptor strategy is developed to improve the PA signals of the resulting semiconducting polymer (PATQ-MP) in the NIR-II window with improved brightness, higher S/N ratio, and better photothermal conversion efficiency compared to polymers with the same main-chain structure containing a symmetric acceptor. DFT analysis showed that PATQ-MP containing an asymmetric acceptor monomer had a larger dihedral angle, which effectively improved the PA signal intensity by enhancing the TICT effect. The PEG-encapsulated PATQ-MP nanoparticles exhibit promising performance in the PA imaging of mouse tumors in vivo, demonstrating the clear identification of microvessels as small as 100 µm along with rapid metabolism within a span of 5 h. Therefore, this work provides a unique molecular design strategy for improving the signal intensity of PA imaging in the NIR-II window.

Embedding Nano-Piezoelectrics into Heterointerfaces of S-Scheme Heterojunctions for Boosting Photocatalysis and Piezophotocatalysis.

Step-scheme (S-scheme) heterojunctions have exhibited great potential in photocatalysis due to their extraordinary light harvesting and high redox capacities. However, inadequate S-scheme recombination of useless carriers in weak redox abilities increases the probability of their recombination with useful ones in strong redox capabilities. Herein, a versatile protocol is demonstrated to overcome this impediment based on the insertion of nano-piezoelectrics into the heterointerfaces of S-scheme heterojunctions. Under light excitation, the piezoelectric inserter promotes interfacial charge transfer and produces additional photocarriers to recombine with useless electrons and holes, ensuring a more thorough separation of powerful ones for CO2 reduction and H2 O oxidation. When introducing extra ultrasonic vibration, a piezoelectric polarization field is established, which allows efficient separation of charges generated by the embedded piezoelectrics and expedites their recombination with weak carriers, further increasing the number of strong ones participating in the redox reactions. Encouraged by the greatly improved charge utilization, significantly enhanced photocatalytic and piezophotocatalytic activities in CH4 , CO, and O2 production are achieved by the designed stacked catalyst. This work highlights the importance in strengthening the necessary charge recombination in S-scheme heterojunctions and presents an efficient and novel strategy to synergize photocatalysis and piezocatalysis for renewable fuels and value-added chemicals production.

Expression and roles of As-NUPR1 protein from Artemia sinica during embryo development and in response to salinity stress.

As-NUPR1, a stress-related protein, plays an important role in post-diapause during embryonic development in the brine shrimp Artemia sinica. In the present study, successful expression of As-NUPR1 from the cDNA sequence isolated from A. sinica was demonstrated using a prokaryotic expression system. The recombinant protein consisted of 132 amino acids with a molecular weight of 15 kDa, and a predicted isoelectric point of 7.17. As-NUPR1 polyclonal antibodies were prepared by immunization of Balb/c mice with purified recombinant As-NUPR1 protein as an antigen, and immunological studies were carried out. Expression of As-NUPR1 during different developmental stages of the embryo and in response to salinity stress was analyzed in A. sinica using Western blots. The experimental results showed that the expression of As-NUPR1 is widely distributed at different developmental stages in A. sinica, and there was no tissue or organ specificity. Expression of As-NUPR1 decreased gradually during the diapause termination stage of embryo development, after which there was a general increase in expression after breaking the shell. In addition, As-NUPR1 expression was highly upregulated under conditions of high salinity. These results suggest that the As-NUPR1 protein is a stress-related protein that plays a role in protecting embryos from high salt damage in different embryonic developmental stages, especially during the post-diapause period.

Cloning and expression patterns of the brine shrimp (Artemia sinica) glycogen phosphorylase (GPase) gene during development and in response to temperature stress.

Glycogen serves as a metabolic reserve and is involved in macromolecular synthesis. Glycogen phosphorylase (GPase) is a key enzyme involved in intracellular glycogen catabolism, catalyzing the first step in glycogen degradation. In the diapause, GPase catalyzes glycogen into the closely related molecule, sorbitol. In this study, the full-length cDNA of the GPase gene (2,790 bp) was isolated from Artemia sinica for the first time by rapid amplification of cDNA ends technology. The GPase gene encoded a protein of 853 amino acids belonging to the Glycosyltransferase GTB type superfamily. The expression pattern and location of GPase were investigated at various stages during the embryonic development of A. sinica using real-time PCR and in situ hybridization. High GPase expression was detected at the 0 and 5 h stages. Subsequently, expression declined and was maintained at a low level during the stages from 10 to 40 h following by a small increase at day 3. Expression was downregulated at temperatures ranging from 25 to 20 °C and was subsequently upregulated in the range 15-5 °C. In situ hybridization assays showed wide distribution of the GPase gene during different developmental stages. From the results of this study, we conclude that the GPase gene expression is stress-related and might play an important role in Artemia development and metabolism.

Cloning and expression of the sorbitol dehydrogenase gene during embryonic development and temperature stress in Artemia sinica.

Sorbitol dehydrogenase (SDH) catalyzes the interconversion of polyols and ketoses, using zinc and NAD(+) as cofactors. SDH converts sorbitol into fructose and plays an important role in the sorbitol metabolic pathway and in the early embryonic development of many invertebrates. Sorbitol usually accumulates in diapause embryos of insects to protect the embryos from frostbite, which indicates the vital function of SDH in the diapause and diapause-termination stages of embryo development. In this study, a 1311-bp full-length cDNA of As-sdh, including a 28-bp 5' UTR and a 59-bp 3' UTR, was cloned from Artemia sinica. This gene encodes 348 amino-acid proteins. Bioinformatic analysis revealed that this gene is highly conserved in arthropods. The expression patterns of As-sdh were investigated during different stages of embryonic development using real-time PCR and in situ hybridization. As-sdh was expressed at relatively high levels during the 0h embryonic stage, and transcript levels were quite high in 5- and 7-day-old embryos. In situ hybridization analysis showed that As-sdh is expressed in a widely dispersed pattern before incubation but is mainly concentrated on the body surface and the inner wall of the alimentary tract after the nauplius stage. Our results suggest that As-sdh is integral to the process of diapause and diapause termination in A. sinica.

Molecular cloning, characterization and expression analysis of ubiquitin protein ligase gene (As-ubpl) from Artemia sinica.

Ubiquitylation is an important protein post-translational regulation pathway, which is involved in controlling protein degradation, tumor occurrence and cell cycle regulation. E3 ubiquitin protein ligase (UBPL) plays a crucial role of the conjugation of activated ubiquitin to protein substrates and leads to targeting proteins for degradation by the proteasome. We amplified one full-length cDNA of the A. sinica UBPL (As-ubpl) gene by RACE technology. The full-length cDNA of As-ubpl is composed of 2931 bp, with a 2571 bp open reading frame (ORF) that encodes a polypeptide of 856 amino acids with a C2 domain, two domains with two conserved Trp (W) residues (WW) and a homologous to E6-AP Carboxyl Terminus (HECT) domain. The amount of As-ubpl showed from real-time PCR indicates that a high expression levels of As-ubpl at 20 h, 40 h and 3 days of embryo development, with highest expression levels appearing in the larval stage (40 h). Furthermore, As-ubpl transcripts were highly up-regulated under salinity (50‰) and low temperature stress (15 °C). These results indicate that As-ubpl is involved in protein regulation of the postdiapause development and in responses to salinity and low temperature stress.

Expression and prognostic impact of PRL-3 in lymph node metastasis of gastric cancer: its molecular mechanism was investigated using artificial microRNA interference.

High PRL-3 expression had been reported to have close association with lymph node metastasis (LNM) of gastric cancer. However, the prognostic significance of highly expressing PRL-3 in LNM of human gastric cancer and the role in the metastasis remain unclear. Our study examined PRL-3 expression both in the LNM (n = 107) and in the primary lesion (n = 137) of gastric cancer, and compared the overall survival rates. RNA interference, induced by recombinant plasmid pcDNA.rPRL3-miR expressing artificial PRL-3 miRNA, was employed to knockdown PRL-3 expression in human SGC7901 gastric cancer cells. Invasion assay and migration assay in vitro were conducted to determine the role of PRL-3 in the metastasis. The role of PRL-3 in the proliferation of SGC7901 cells and tumor growth were also determined. We observed that high PRL-3 expression was more frequently detected in the LNM than in the matched primary lesion (72.9 vs. 47.7%, p < 0.001). Furthermore, the overall survival rate of the patients with high expression of PRL-3 in the LNM was significantly less than those with moderate/low expression (p = 0.003). Importantly, knockdown of PRL-3 can significantly reduce both invasion and migration potencies of SGC7901 cells (p < 0.001), and significantly suppressed the proliferation of SGC7901 cells and slowed down the tumor growth (p < 0.001). It was concluded that high expression of PRL-3 in the LNM had a negative impact on the prognosis of the patients, and plays important roles in LNM of gastric cancer and the tumor growth, which can be a potential therapeutic target and a prognostic factor.