Polysaccharide-based gold nanomaterials: Synthesis mechanism, polysaccharide structure-effect, and anticancer activity.

Polysaccharide-based gold nanomaterials have attracted great interest in biomedical fields such as cancer therapy and immunomodulation due to their prolonged residence time in vivo and enhanced immune response. This review aims to provide an up-to-date and comprehensive summary of polysaccharide-based Au NMs synthesis, including mechanisms, polysaccharide structure-effects, and anticancer activity. Firstly, research progress on the synthesis mechanism of polysaccharide-based Au NMs was addressed, which included three types based on the variety of polysaccharides and reaction environment: breaking of glycosidic bonds via Au (III) or base-mediated production of highly reduced intermediates, reduction of free hydroxyl groups in polysaccharide molecules, and reduction of free amino groups in polysaccharide molecules. Then, the potential effects of polysaccharide structure characteristics (molecular weight, composition of monosaccharides, functional groups, glycosidic bonds, and chain conformation) and reaction conditions (the reaction temperature, reaction time, pH, concentration of gold precursor and polysaccharides) on the size and shape of Au NMs were explored. Finally, the current status of polysaccharide-based Au NMs cancer therapy was summarized before reaching our conclusions and perspectives.

Disulfiram-loaded hollow copper sulfide nanoparticles show anti-tumor effects in preclinical models of colorectal cancer.

Colorectal cancer is one of the most common malignancies causing the majority of cancer-related deaths. There is an urgent need to develop new anticancer modalities. Recently, efforts have been made to turn clinically approved drugs into anticancer agents in specific tumor microenvironments via NPs. Disulfiram (DSF) as an effective copper (Cu2+)-dependent anti-tumour drug, which has been more widely used in antitumor research. Here, we constructed a novel therapeutic nanoplatforms, DSF@CuS, by encapsulating DSF in hollow CuS NPs to enable in situ chemoselective activation of DSF and hyperthermal amplified chemotherapy. The anticancer effect of DSF was enhanced by the thermal energy generated under NIR irradiation through the intrinsic photothermal conversion of CuS. As a result, significant apoptosis was induced in vitro, and tumor elimination was achieved in vivo. Collectively, DSF@CuS combined with photothermal therapy can significantly promote the apoptosis of CT26 colorectal cancer cells both in vitro and in vivo, providing a potential theoretical agent for the treatment of colorectal cancer.

Construction Of High Loading Natural Active Substances Nanoplatform and Application in Synergistic Tumor Therapy.

Background: Natural bioactive substances have been widely studied for their superior anti-tumor activity and low toxicity. However, natural bioactive substances suffer from poor water-solubility and poor stability in the physiological environment. Therefore, to overcome the drawbacks of natural bioactive substances in tumor therapy, there is an urgent need for an ideal nanocarrier to achieve high bioactive substance loading with low toxicity. Materials and Methods: Face-centered cubic hollow mesoporous Prussian Blue (HMPB) NPs were prepared by stepwise hydrothermal method. Among them, PVP served as a protective agent and HCl served as an etching agent. Firstly, MPB NPs were obtained by 0.01 M HCl etching. Then, the highly uniform dispersed HMPB NPs were obtained by further etching with 1 M HCl. Results: In this work, we report a pH-responsive therapeutic nanoplatform based on HMPB NPs. Surprisingly, as-prepared HMPB NPs with ultra-high bioactive substances loading capacity of 329 µg mg-1 owing to the large surface area (131.67 m2 g-1) and wide internal pore size distribution (1.8-96.2 nm). Moreover, with the outstanding photothermal conversion efficiency of HMPB NPs (30.13%), natural bioactive substances were released in the tumor microenvironment (TME). HMPB@PC B2 achieved excellent synergistic therapeutic effects of photothermal therapy (PTT) and chemotherapy (CT) in vivo and in vitro without causing any extraneous side effects. Conclusion: A biocompatible HMPB@PC B2 nanoplatform was constructed by simple physical adsorption. The in vitro and in vivo experiment results demonstrated that the synergy of PTT/CT provided excellent therapeutic efficiency for cervical cancer without toxicity. Altogether, as-designed nanomedicines based on natural bioactive substances may be provide a promising strategy for cancer therapy.

Global-local consistency benefits memory-guided tracking of a moving target.

INTRODUCTION: Previous findings have demonstrated that several Gestalt principles do facilitate VSTM performance in change detection tasks. However, few studies have investigated the role of and time-course of global-local consistency in motion perception. METHODS: Participants were required to track a moving target surrounded by three different backgrounds: blank, inconsistent, or consistent. Global-local objects were be bound to move together (covariation). During the PMT, participants had to follow the moving target with their eyes and react as fast as possible when the target had just vanished behind the obstruction or would arrive at a predetermined point of interception. Variable error (VE) and constant error (CE) of estimated time-to-contact (TTC) and gain of smooth pursuit eye movements were calculated in various conditions and analyzed qualitatively. RESULTS: Experiment 1 established the basic finding that VSTM performance could benefit from global-local consistency. Experiment 2 extended this finding by eye-tracking device. Both in visible phase and in occluded phase, CEs were smaller for the target in a consistent background than for the target in an inconsistent background and for the target in a blank background, with both differences significant (ps < .05). However, the difference in VE among three conditions was not significant. At early stage (100-250 ms), later stage (2750-3000 ms), and termination stage (5750-6000 ms) of smooth pursuit, the velocity gains were higher in the trials with consistent backgrounds than in the trials with inconsistent backgrounds and blank backgrounds (ps < .001). With the exception of 100-250 ms phase, the means did not differ between the inconsistent background and the blank background trials (ps > .1). CONCLUSIONS: Global-local consistency could be activated within the first few hundred milliseconds to prioritize the deployment of attention and eye movement to component target. Meanwhile, it also removes ambiguity from motion tracking and TTC estimation under some unpredictable conditions, leading to the consistency advantage during smooth-pursuit termination phase. Global-local consistency may act as an important information source to TTC estimation and oculomotor response in PMT.

Expression of exogenous dsRNA by Lecanicillium attenuatum enhances its virulence to Dialeurodes citri.

BACKGROUND: Dialeurodes citri is an important pest in citrus-producing areas of the world. Lecanicillium attenuatum parasitizes D. citri and kills it, suggesting a potential approach for the biological control of pests. However, the low virulence of the fungus and its slow rate of killing have limited its commercial competitiveness. The objective reason for these disadvantages is immunological rejection by the host. Our strategy was to use fungi to express the double-stranded RNA (dsRNA) of the host immune genes. The fungal hyphae release siRNA at the time of infection, thus interfering with the expression of immune genes in the host and facilitating fungal invasion. RESULTS: We selected prophenoloxidase (DcPPO), prophenoloxidase-activating factor (DcPPO-AF), and lysozyme (DcLZM) as target genes to construct intron-splicing hairpin RNA expression vectors and to successfully obtain transgenic fungi. Two days after infection, the immune genes of D. citri showed varying degrees of silencing compared with those in the positive control group. The median lethal concentration (LC50 ; spores mL-1 ) values of La::GFP, La::DcPPO, La::DcPPO-AF, and La::DcLZM were 9.63 × 104 , 2.66 × 104 , 1.21 × 105 , and 3.31 × 104 , respectively. The 50% lethal time (LT50 ) values of these fungi were 5.15, 3.60, 5.34, and 4.04 days, respectively. The virulence of La::DcPPO and La::DcLZM increased 3.62- and 2.91-fold, respectively, and their LT50 decreased by 30.10% and 21.55%, respectively. CONCLUSIONS: The results indicate that this method, which uses tens of thousands of hyphae to inject dsRNA to improve the virulence of transgenic fungi, can play a greater role in the prevention and control of pests in the future. © 2018 Society of Chemical Industry.

Effect of six insecticides on three populations of Bactrocera (Tetradacus) minax (Diptera: Tephritidae).

The Chinese citrus fruit fly, Bactrocera minax is one of the most economically important and aggressive pests threatening the Chinese citrus industry. In order to provide some recommendations for the improvement of integrated pest management of this species, the authors evaluated the toxicity of 6 insecticides on the second stage larvae, fourth stage larvae, and adult flies from multiple geographical B. minax populations. In addition, the influences of each pesticide on pupation and emergence were examined for one population, from Hanzhong. The 6 reagents displayed a wide range of toxicity on various stages of B. minax. Abamectin and Dichlorphos displayed the highest and lowest toxicities, respectively. All of the insecticides had negative effects on pupation and emergence of B. minax from Hanzhong, while Chlorpvrifos had the strongest impact on pupation, and Phoxim had the strongest influence on emergence. Though Phoxim and Chlorpvrifos were both effective, these insecticides belong to the class of organophosphorus pesticides, and their use should be reduced in orchards because of their high toxicity and long residual period.