ß-Cyclodextrin/Azobenzene Microspheres Loaded with Paraquat Are Safe and Effective.

Although paraquat is a widely used herbicide, it is toxic to humans if ingested or absorbed through an open wound. To improve the safety of paraquat, a new formulation of paraquat based on photoresponsive polymers was exploited. Photoresponsive ß-cyclodextrin polymer microspheres (AZO-CD) were synthesized via a host-guest interaction between ß-cyclodextrin and azobenzene. AZO-CD were characterized by Fourier transform infrared spectrometry, circular dichroism, ultraviolet (UV) spectrophotometry, and thermogravimetric analysis, and their photoresponsiveness was also evaluated. AZO-CD were used to load paraquat, which yielded photoresponsive paraquat-loaded microspheres. For the paraquat-loaded microspheres, irradiation with UV light or sunlight induced the isomerization of azobenzene into the cis form. Then, the cis-azobenzene was liberated from the cavities of the ß-cyclodextrin. The paraquat-loaded microspheres released paraquat continuously over time. Furthermore, under UV light, the herbicidal capacity of the paraquat-loaded microspheres against barnyard grass was comparable to that of free paraquat at the same dose. Our findings show that loading paraquat into AZO-CD provides a safe and environmentally friendly herbicide formulation.

Fabrication a controlled-release pesticide for improving UV-shielding properties and reducing toxicity via coating polydopamine.

Controlled-release formulations (CRFs) have potential applications in modern agriculture, for it can not only prolong the duration of agrochemicals but also alleviate the adverse effect on non-target organism. In this study, we constructed pyraclostrobin@SiO2@polydopamine microcapsule (Pyr@SiO2@PDA MC). The resulting microcapsule is a near-rod shape (about 1.15 µm), which has a drug-loading efficiency of 55%. Fourier transform infrared (FTIR) and thermogravimetric analysis (TG) revealed the successful entrapment of the pesticide. The coating of polydopamine (PDA) endowing the microcapsule with superior UV-shielding properties than pyraclostrobin@SiO2 microcapsule (Pyr@SiO2 MC). Compared with pyraclostrobin emulsifiable concentrate (EC), the Pyr@SiO2@PDA MC exhibited 9.07-, 5.50-, 4.93- and 4.16-fold higher fungicidal activity against Rice blast fungus (Pyricularia oryzae) at concentrations of 0.5, 1, 2 and 4 mg/L. Moreover, acute toxicity tests demonstrated that the sample on zebrafish with lower toxicity on the first day. These results showed that the obtained microcapsule may process broader application potential in agriculture.

Compound pesticide controlled release system based on the mixture of poly(butylene succinate) and PLA.

Controlled release system has been widely developed and utilised in agriculture to optimise efficacy and minimise environmental pollution. Here, the azoxystrobin and difenoconazole compound pesticide microsphere was constructed by the solvent evaporation method. Blending poly (butylene succinate) (PBS) and poly (lactic acid) (PLA) as shells, in order to increase its entrapment efficiency and match the goal of complex synergism. The resulting microsphere processes high entrapment efficiency with a mean diameter of 7.2 µm. Acute toxicity suggested microsphere on zebrafish was moderate toxicity. Comparative studies revealed that the microsphere had a longer period of sustained release than difenoconazole-azoxystrobin (5:8) 32.5% w/v suspension concentrate (SC). In addition, the concentration ratio of active ingredients closed to the optimum compound stoichiometry, which can achieve the objective of improving the efficacy of the pesticides. These results demonstrated that such a compound pesticide microsphere delivery system may be a considerable potential for further exploration.

Intracellular Enzyme-Responsive Profluorophore and Prodrug Nanoparticles for Tumor-Specific Imaging and Precise Chemotherapy.

Responsive drug delivery systems possess great potential in disease diagnosis and treatment. Herein, we develop an activatable prodrug and fluorescence imaging material by engineering the endogenous NAD(P)H:quinone oxidoreductase-1 (NQO1) responsive linker. The as-prepared nanomaterials possess the NQO1-switched drug release and fluorescence enablement, which realizes the tumor-specific chemotherapy and imaging in living mice. The enzyme-sensitive prodrug nanoparticles exhibit selectively potent anticancer performance to NQO1-positive cancer and ignorable off-target toxicity. This work provides an alternative strategy for constructing smart prodrug nanoplatforms with precision, selectivity, and practicability for advanced cancer imaging and therapy.

Optimization of Vero Cells Grown on a Polymer Fiber Carrier in a Disposable Bioreactor for Inactivated Coxsackievirus A16 Vaccine Development.

At present, there are no vaccines available for hand, foot, and mouth disease, which is caused by Coxsackie virus A16 (CVA16) infection. In the present study, we isolated epidemic strains of CVA16 and optimized the production of the virus in Vero cells. The system comprised growing the infected cells on polymer fiber paper carriers in a serum-free medium containing 0.5% (w/v) lactalbumin hydrolysate a mini bioreactor. Disposable Bioflo310 and AmProtein Current perfusion bioreactors were used to monitor virus infection and Vero cell culture. The total number of cells increased from 1.5 × 109 to 3.0 × 1010. In our optimized culture process, the virus titer reached 7.8 × 107 TCID50/mL at three days after infection. The inactivated CVA16 prepared from our optimized culture procedure elicited a slightly higher neutralizing antibody titer compared with that derived from routine culture procedures. These results will promote the large-scale production of inactivated CVA16 vaccines using nonwoven polymer fiber paper cell cultures.

Self-destructive PEG-BODIPY nanomaterials for photodynamic and photothermal therapy.

Photoactive nanoparticles are an important platform for multimodal imaging and phototherapy of tumors. Herein, amphiphilic photosensitizers were made from boron dipyrromethene (BODIPY) and poly(ethylene glycol) (PEG2k) by using a thioketal linker, which is reactive oxygen species-responsive. The photosensitizers could form stable nanoparticles in aqueous solution. The resulting nanoparticles could simultaneously produce heat and reactive oxygen species upon irradiation to achieve combined photothermal and photodynamic therapy. The produced singlet oxygen could destroy the thioketal linker, and accelerate the destruction of nanoparticles. In addition, the near-infrared fluorescence and photoacoustic imaging ability of nanoparticles can reflect the biodistribution and destiny of nanoparticles. This work highlights the application of integrated diagnostic and therapeutic photosensitizers in carriers.

Rational Design of BODIPY-Diketopyrrolopyrrole Conjugated Polymers for Photothermal Tumor Ablation.

Conjugated polymers (CPs) have drawn growing attention in cancer phototherapy and imaging due to their large extinction coefficients, robust photostability, and good biocompatibility. Herein, we propose a new type of photothermal therapy materials on the basis of BODIPY-diketopyrrolopyrrole CPs, where the number of methyl substituents at the ß and ß' positions on BODIPYs is variable, allowing us to investigate the interplay between the structure of the monomers and the related properties of CPs. Combining the experimental data with theoretical calculations, we concluded that with the decrease of the number of methyl moieties on the ß and ß' positions of BODIPY, the polymerization degree and the solubility of the obtained CPs improved and the polymeric spatial planarization and degrees of conjugation increased, inducing the bathochromic shift of absorption, which resulted in the absorption spectra getting closer to the near-infrared region and more conducive to the application of the conjugated polymers in vivo. Afterward, the CP nanoparticles were constructed and their photothermal activity in cancer therapy was validated by a series of in vitro and in vivo experiments. In this paper, we provide a new way to manipulate properties of CPs with great potential in photothermal therapy through structural engineering.

Gut region influences the diversity and interactions of bacterial communities in pikas (Ochotona curzoniae and Ochotona daurica).

The mammalian microbial communities in the gastrointestinal tract (GIT) play important roles in host nutrition and health. However, we still lack an understanding of how these communities are organized across GIT in natural environments. Here, using 16S rRNA gene sequencing, we analyzed the bacterial community diversity, network interactions and ecosystem stability across five gut regions (mouth, stomach, small intestine, cecum and colon) emanating from two common pika species in China, including Plateau pikas (Ochotona curzoniae) inhabiting high-altitude regions, as well as Daurian pikas (O. daurica) occupying low-altitude areas. The relative abundances of dominant Bacteroidetes and Firmicutes exhibited an increasing trend from mouth to colon. Cecum and colon harbored higher bacterial diversity compared with other anatomical regions. Gut region significantly influenced the structure of bacterial communities in the GIT. Network analysis indicated that topological features showed marked variations among gut regions. Interestingly, the ecosystem stability of bacterial communities increased gradually from mouth to colon. Our results suggest that gut region influences the diversity, structure and network interactions of bacterial communities in pikas. For hindgut-fermenting herbivorous mammals, relatively higher bacterial diversity and ecosystem stability in the cecum may provide a favorable condition for the fermentation of indigestible plant polysaccharides.