高透明度和高强度的纳米粘合水凝胶贴片用于组织粘附

本研究旨在设计和制备一种具有优异机械性能和生物相容性的双层结构壳聚糖水凝胶粘合贴片,并借助纳米粘合策略评估其组织粘附性能。以物理交联构建坚韧的壳聚糖水凝胶作为背膜,随后通过原位光交联制备粘合剂水凝胶层,形成一体化的壳聚糖水凝胶粘合贴片。利用纳米胶水促进贴片与基底之间的纳米粘合。表面活化的二氧化硅纳米颗粒作为类似于纳米胶的界面连接器,促进水凝胶与基底的结合,以建立水凝胶贴片与生物组织之间的粘附关系。分析结果显示,水凝胶贴片在体外对生物组织的粘合能量为282 J/m^(2),爆破压力为450 mmHg(1 mmHg=0.133 kPa)。该贴片具有4.3 MPa的拉伸强度、65%的断裂伸长率和3.82 kJ/m^(2)的断裂韧性,具有出色的机械性能。此外,这种基于纳米粘合剂的壳聚糖水凝胶粘合贴片具有高透明度和优异的生物相容性,有望在组织修复和药物输送等多个生物医学领域得到应用,为临床外科手术的发展提供坚实的材料基础。

Hydrothermal synthesis of silver nanoparticles in Arabic gum aqueous solutions

Finely divided silver nanoparticles were synthesized via the hydrothermal method. Arabic gum （AG） was used as both the reductant and steric stabilizer without any other surfactant. By adjusting the reaction temperature, mass ratio of AG to AgNO3, and reaction time, silver nanoparticles with different morphological characteristics could be obtained. The products were characterized by UV-Vis, FTIR, TEM, SEM, and XRD measurements. It was found that temperature and AG played an important role in the synthesis of mono-disperse silver nanoparticles. Well dispersed and quasispherical silver nanoparticles were obtained under the optimal synthesis conditions of 10 mmol/L AgNO3, m（AG）/m（AgN03）= l：1, 160 ℃ and 3 h.

PREPARATION AND PROPERTIES OF CLAY/POLY（N-ISOPROPYLACRYLAMIDE-co-A CRYL AMIDE） NANOCOMPOSITE HYDROGELS

A series of clay/poly（N-isopropylacrylamide-co-acrylamide） nanocomposite hydrogels （S-N-M gels） have been successfully prepared by in situ polymerization. The mechanical properties, swelling behavior of S-N-M gels and the transparency changes during polymerization of S-N-M gels have been systematically investigated. Compared to traditional hydrogels, S-N-M gels show excellent tensile properties and their swelling ratio increases with increasing acrylamide （AAm） content. The results of stress relaxation indicate that the stress loss decreases with increasing AAm content. It was surprisingly found that the transparency during all S-N-M gel synthesis changes abruptly, and the changes become more abrupt with increasing N-isopropylacrylamide content. It was concluded that the fact may be related to the hydrophilicity of copolymers. The weaker the hydrophilicity of copolymer, the more apparent the transparency change during S-N-M gels polymerization. We believe the relationship between hydrophilicity of copolymer and transparency changes will help to design novel nanocomposite hydrogels.

Halloysite Nanotube Composited Thermo-responsive Hydrogel System for Controlled-release

Halloysite nanotube-composited thermo-responsive hydrogel system has been successfully developed for controlled drug release by copolymerization of N-isopropylacrylamide （NIPAM） with silane-modified halloysite nanotubes （HNT） through thermally initiated free-radical polymerization. With methylene blue as a model drug, thermo-responsive drug release results demonstrate that the drug release from the nanotubes in the composited hy-drogel can^be well controlled by manipulating the environmental temperature. When the hydrogel network is swol- len at temperature below the lower critical solution temperature （LCST）, drug releases steadily from lumens of the embedded nanotubes, whereas the drug release stops when hydrogel shrinks at temperature above the LCST. The release of model drug from the HNT-composited hydrogel matches well with its thermo-responsive volume phasetransition, and shows characteristics of well controlled release. The design strategy and release results of the pro- posed novel HNT-composited thermo-responsive hydrogel system provide valuable guidance for designing respon- s_i_ve nanocomposites for controlled-release of active agents.

Research on Polymer Materials in Bio Medical and Its Application

Intelligent hydrogels is as drug carrier, and it has a good application prospect. There are some changes factors in the human environment, such as temperature, pH. Therefore, the temperature sensitive hydrogels and pH sensitive hydrogels can release system for drugs in the body. So the paper detailed descript a novel MWCNTs good dispersion of PMAA/MWCNTs nano hybrid hydrogels. The introduction of MWCNTs significantly increased the hydrogel pH response and mechanical strength, and depends on the MWCNTs component ratio, particle size and concentration of cross-linking agent. The study found, swelling rate of hybrid hydrogels was faster than the pure PMAA hydrogel, and the swelling behavior were explained. The compression stress-strain experiments should be found, MWCNTs load transfer plays an important role in improving the mechanical properties of the hybrid hydrogels network compression.

Supramolecular protein glue to boost enzyme activity

Proteins possess many biological functions.However, they can easily degrade or aggregate, thus losing their bioactivity. Therefore, it is very important to develop materials capable of interacting with proteins and forming nanostructures for protein storage and delivery. In this study,we serendipitously found a novel peptide-based supramolecular protein glue(Nap-GFFYK(γE)2-NH2, compound 1) that could co-assemble with proteins into nanofibers and hydrogels. We found that compound 1 rapidly folded into a β-sheet conformation upon contact with many proteins but not with polymers. Total internal reflection fluorescence microscopy(TIRFM) images clearly show the formation of co-assembled nanofibers by proteins and the peptide. The supramolecular protein glue could improve the dispersion of enzymes(lipase and lysozyme) and therefore enhance their catalytic activity,especially at high temperatures. More importantly, the supramolecular protein glue could co-assemble with two enzymes, glucose oxidase/horseradish peroxidase(GOx/HRP)and GOx/cytochrome c(cyt c), to form nanofibers that significantly enhanced the catalytic activity of tandem enzymatic reactions. We envisioned the great potential of our supramolecular protein glue for protein storage, delivery, and bioactivity manipulation.

Nanoindentation characteristics of cement with different mineral admixtures

In order to determine the effects of different mineral admixtures including fly ash （FA）, blast furnace slag （BFS） and metakaolin （MK） on hydration product phases from the nanoscale structure perspective, nanoindentation characteristics of the samples with similar 28-day strengths have been investigated. The results indicate that the volume fractions of porosity in po- rosity and hydration product phases of the samples with the same kind of mineral admixture are almost equal to each other, and are greater than that of the sample without mineral admixture. Mineral admixtures especially MK can decrease remarkably the volume fractions of CH in porosity and hydration product phases, and there exists a good linear relationship between the （AI＋Si）/Ca molar ratio of cementitious materials chemical compositions and the volume fraction of HD C-S-H gel in C-S-H gel. Therefore, it is possible to predict the volume fraction change of HD C-S-H gel in C-S-H gel by simply calculating the （AI＋Si）/Ca molar ratio of cementitious materials with similar 28-day strengths under the constant water-binder ratio.

Solvent switching and purification of colloidal nano- particles through water/oil Interfaces within a density gradient

Traditional post-treatment of colloidal nanoparticles （NPs） usually involves repeated centrifugation-wash-sonication processes to separate NPs from the original synthetic environment; however, such separation processes have either high energy cost or low efficiency and tend to cause aggregation. Here we show a general and scalable colloid post-processing technique based on density gradient centrifugation through water/oil interfaces. Such a one-step technique can switch the solvent in a colloid at almost any concentration without aggregation, and meanwhile purify colloidal nanoparticles by separating them from by-products and environmental impurities. Droplet sedimentation was shown to be the mechanism of this one-step concentration/purification process, and mathematical modeling was established to quantify the accumulation and sedimentation velocities of different NPs.

Adhesive aero-hydrogel hybrid conductor assembled from silver nanowire architectures

Conductive and adhesive hydrogels are promising materials for designing bioelectronics.To satisfy the high conductivity of bioelectronic devices,metal nanomaterials have been used to fabricate composite hydrogels.However,the fabrication of a conductive-nanomaterial-incorporated hydrogel with high performance is a great challenge because of the easy aggregation nature of conductive nanomaterials making processing difficult.Here,we report a kind of adhesive aero-hydrogel hybrid conductor(AAHC)with stretchable,adhesive and anti-bacteria properties by in situ formation of a hydrogel network in the aerogel-silver nanowires(AgNWs)assembly.The AgNWs with good conductivity are wellintegrated on the inner-surface of shape-memory chitosan aerogel,which created a conductive framework to allow hydrogel back-filling.Reinforcement by the aerogel-silver makes the hybrid hydrogel tough and stretchable.Functional groups from the hydrogel allow strong adhesion to wet tissues through molecular stitches.The inherent bacteria-killing ability of silver ions endows the conductive hydrogel with excellent anti-bacteria performance.The proposed facile strategy of aerogel-assisted assembly of metal nanomaterials with hydrogel opens a new route to incorporate functional nanoscale building blocks into hydrogels.

Hydrothermal synthesis of nano-silicon from a silica sol and its use in lithium ion batteries

There have been few reports concerning the hydrothermal synthesis of silicon anode materials. In this manuscript, starting from the very cheap silica sol, we hydrothermally prepared porous silicon nanospheres in an autoclave at 180 ℃. As anode materials for lithium-ion batteries （LIBs）, the as-prepared nano-silicon anode without any carbon coating delivers a high reversible specific capacity of 2,650 mAh·g^-1 at 0.36 A·g^-1 and a significant cycling stability of about 950 mAh·g^-1 at 3.6 A·g^-1 during 500 cycles.

Rotating magnetic field-controlled fabrication of magnetic hydrogel with spatially disk-like microstructures

Composite biomaterials with controllable mi- crostructures play an increasingly important role in tissue engineering and regenerative medicine. Here, we report a magnetic hydrogel composite with disk-like microstructure fabricated by assembly of iron oxide nanopartides during the gelation process in the presence of rotating magnetic field. It should be mentioned that the iron oxide nanoparticles here were synthesized identically following techniques of Fer- umoxytol that is the only inorganic nanodrug approved by FDA for clinical applications. The microstructure of nano- particles inside the hydrogel was ordered three-dimensionally due to the twist of the aligned chains of magnetic nano- particles which leads to the lowest state of systematic energy. The size of microstructure can be tuned from several micro- meters to tens of micrometers by changing the assembly parameters. With the increase of microstructure size, the magnetothermal anisotropy was also augmented. This result confirmed that the assembly-induced anisotropy can occur even for the several micron aggregates of nanopartides. The rotating magnetic field-assisted technique is cost-effective, simple and flexible for the fabrication of composite hydrogel with ordered microstructure. We believe it will be favorable for the quick, green and intelligent fabrication of some com- posite materials.