Highly efficient intracellular drug delivery with a negatively charged hyperbranched polysulfonamine

Efficient intracellular translocation is achieved using an easily prepared hyperbranched polysulfonamine that remains negatively charged at physiological pH. Investigations on the cellular uptake mechanism and the subcellular distribution of PSA are reported. The in vitro cytotoxicity of PSA is found to be low. Using doxorubicin as a model drug, a PSA/drug complex is prepared by electrostatic interaction with a high drug payload that exhibits a controlled release in response to pH. Efficient intracellular drug delivery, strong growth inhibition of tumor cells, and low cytotoxicity to normal cells are observed. The results suggest a possible way to utilize anionic polymers for intracellular delivery of therapeutic moieties or drugs.     

From smectic to columnar phase of polypedal liquid crystals based on tetrathiafulvalene/1,3-dithiol-2-thione and cholesterol

Bipedal 1,3-dithiole-2-thiones attached two cholesteryl through a ω-thioalkanoyloxy spacer of varying length were synthesized. The bipedals were easily transformed to the appropriate tetrapedal tetrathiafulvalene derivatives by self-coupling reaction in net triethyl phosphite. All the synthesized compounds exhibit mesogenic phases in a wide temperature region, no crystallization but vitrifying to form glassy mesogens during cooling from the isotropic melt. The liquid crystals with shorter spacer (n=2-6) exhibited only a smectic A phase and those with the longest spacer (n=7) exhibited only a hexagonal columnar. In these series, the molecular packing depended on the length of spacers.     

石墨烯基复合材料对污水净化的研究进展*

石墨烯基复合材料具有较大的比表面积、较高的表面能,对污染物具有较强的吸附能力,可用于去除水中的污染物,从而达到净化污水的目的。本文综述了几种石墨烯基复合材料的制备和其对水中化学类物质,如重金属离子、有机染料和其他污染物的吸附特性,并简述了溶液的酸度、接触时间和金属离子初始浓度等对石墨烯基复合材料吸附污染物的影响。     

Nano-enabled Quenching of Bacterial Communications for the Prevention of Biofilm Formation

Biofilm formation is a major threat to industry, the environment and human health. While killing of embedded microbes in biofilms may inevitably lead to the evolution of antimicrobial resistance (AMR), catalytic quenching of bacterial communications by lactonase is a promising antifouling approach. Given the shortcomings of protein enzymes, it is attractive to engineer synthetic materials to mimic the activity of lactonase. Herein, an efficient lactonase-like Zn−N_x−C nanomaterial was synthesized by tuning the coordination environment around zinc atoms to mimic the active domain of lactonase for catalytical interception of bacterial communications in biofilm formation. The Zn−N_x−C material could selectively catalyze 77.5 % hydrolysis of N-acylated-L-homoserine lactone (AHL), a critical bacterial quorum sensing (QS) signal in biofilm construction. Consequently, AHL degradation downregulated the expression of QS-related genes in antibiotic resistant bacteria and significantly prevented biofilm formation. As a proof of concept, Zn−N_x−C-coated iron plates prevented 80.3 % biofouling after a month exposure in river. Overall, our study provides a nano-enabled contactless antifouling insight to avoid AMR evolution by engineering nanomaterials for mimicking the key bacterial enzymes (e.g., lactonase) functioning in biofilm construction.     

Preparation of CdS nanocrystals within supramolecular self-assembled nanoreactors and their phase transfer behavior

A new strategy for the synthesis of CdS nanocrystals (NCs) within supramolecular self-assembly nanoreactors has been described. The self-assembly nanoreactors were readily constructed through the electrostatic interactions and ion pairs between palmitic acid and the terminal amine groups of hyperbranched polymer. In a chloroform/water two-phase system, aqueous Cd (2+) ions were spontaneously encapsulated into the cavities of self-assembly nanoreactors in chloroform. After reaction with S (2-) ions, the CdS NCs with high stability were obtained. By the addition of excess triethylamine, CdS NCs formed in the self-assembly nanoreactors were transferred from organic phase into aqueous phase. After dialysis and rotorary evaporation, aqueous CdS NCs could be redispersed into chloroform solution containing palmitic acid.     

Coded excitation using biphase-coded pulse with mismatched filters for high-frequency ultrasound imaging

A scheme of using phase-coded excitation and mismatched filter compression for high-frequency ultrasound imaging is presented in this paper. Biphase-coded pulses were constructed to excite the transducer. Received signals were compressed with mismatched filters optimized by minimizing peak-sidelobe-level (PSL). Both simulation and experiments were carried out to demonstrate the advantage of this technique. The simulation results demonstrated a possible sidelobe reduction (<-90 dB) with a slightly decrease of the signal-to-noise ratio of less than 1 dB compared with the compression using matched filters alone. The experimental results showed about 14 dB SNR improvement as well as -40 dB sidelobe level when the Barker-13 code excitation with 3-cycle sinusoidal wave carrier was used.     

A simulated annealing hyper-heuristic methodology for flexible decision support

Most of the current search techniques represent approaches that are largely adapted for specific search problems. There are many real-world scenarios where the development of such bespoke systems is entirely appropriate. However, there are other situations where it would be beneficial to have methodologies which are generally applicable to more problems. One of our motivating goals for investigating hyper-heuristic methodologies is to provide a more general search framework that can be easily and automatically employed on a broader range of problems than is currently possible. In this paper, we investigate a simulated annealing hyper-heuristic methodology which operates on a search space of heuristics and which employs a stochastic heuristic selection strategy and a short-term memory. The generality and performance of the proposed algorithm is demonstrated over a large number of benchmark datasets drawn from two very different and difficult problems, namely; course timetabling and bin packing. The contribution of this paper is to present a method which can be readily (and automatically) applied to different problems whilst still being able to produce results on benchmark problems which are competitive with bespoke human designed tailor made algorithms for those problems.     

Antibacterial Nanomaterials: Mechanisms,Impacts on Antimicrobial Resistance and Design Principles

Antimicrobial resistance (AMR) is one of the biggest threats to the environment and health. AMR rapidly invalidates conventional antibiotics, and antimicrobial nanomaterials have been increasingly explored as alternatives. Interestingly, several antimicrobial nanomaterials show AMR-independent antimicrobial effects without detectable new resistance and have therefore been suggested to prevent AMR evolution. In contrast, some are found to trigger the evolution of AMR. Given these seemingly conflicting findings, a timely discussion of the two faces of antimicrobial nanomaterials is urgently needed. This review systematically compares the killing mechanisms and structure-activity relationships of antibiotics and antimicrobial nanomaterials. We then focus on nano-microbe interactions to elucidate the impacts of molecular initiating events on AMR evolution. Finally, we provide an outlook on future antimicrobial nanomaterials and propose design principles for the prevention of AMR evolution.