Mineral formation on dentin induced by nano-bioactive glass

The object of this study was to evaluate the effect of bioactive glass (BG) size on mineral formation on dentin surfaces. Totally demineralized dentin discs were treated using BG suspensions with different particle sizes:i.e., microscale bioactive glass (m-BG), submicroscale bioactive glass (sm-BG) and nanoscale bioactive glass (n-BG). Field-emission scanning electron microscopy and 3D profile measurement laser microscopy were used to observe the surface morphology and roughness. It was found that all BG particles could promoted mineral formation on dentin surfaces, while plug-like depositions were observed on the dentin discs treated by n-BG and they were more acid-resistant. The present results may imply that n-BG has potential clinical application for dentin hypersensitivity treatment.     

Molecular structure and properties of click hydrogels with controlled dangling end defect

In this study, controlled amount of dangling ends is introduced to the two series of poly(ethylene glycol)‐based hydrogel networks with three and four crosslinking functionality by using click chemistry. The structure of the gels with regulated defect percentage is confirmed by comparing the results of low‐field NMR characterization and Monte Carlo simulation. The mechanical properties of these gels were characterized by tensile stress–strain behaviors of the gels, and the results are analyzed by Gent model and Mooney–Rivlin model. The shear modulus of the swollen gels is found to be dependent on the functionality of the network, and decreases with the defect percentage. Furthermore, the value of shear modulus well obeys the Phantom model for all the gels with varied percentage of the defects. The maximum extension ratio, obtained from the fitting of Gent model, is also found to be dependent on the functionality of the network, and does not change with the defect percentage, except at very high defect percentage. The value of the maximum extension ratio is between that predicted from Phantom model and the Affine model. This indicates that at the large deformation, the fluctuation of the crosslinking points is suppressed for some extend but still exists. Polymer volume fractions at various defect percentages obtained from prediction of Flory–Rehner model are found to be in well agreement with the swelling experiment. All these results indicate that click chemistry is a powerful method to regulate the network structure and mechanical properties of the gels. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1227–1236     

Attapulgite grafted with polystyrene via a simultaneous reverse and normal initiation atom transfer radical polymerization

The surface grafting of attapulgite (ATP) with polystyrene (PS) was established via a simultaneous reverse and normal initiation atom transfer radical polymerization (SR&NIATRP). 4‐(chloromethyl)phenyltrimethoxysilane (CMPTMS) chemical bounded on the surface of ATP (ATP‐Cl, Cl‐I) was prepared via one‐step self‐assembly. SR&NI ATRP of styrene was conducted using CuCl₂ complex tris(2‐(dimethylamino)ethyl)amine (Me₆‐TREN) as the catalytic system, initiated by 2,2‐azobis(isobutyronitrile) (AIBN) and ATP‐Cl. FT‐IR, XRD, XPS, TGA and TEM data were consistent with the grafting of benzyl chloride groups and PS chains on ATP surface. The controllability of polymerization was investigated by the kinetics behavior under different molar ratio of AIBN and CuCl₂. The obtained polymer possessed a uniform distribution of molecular weights with a lower polydispersity index of 1.2～1.4. The relationship between polymerization on the surface of ATP and in solution was discussed in detail based on TGA data of hybrid particles and GPC trace of free polymer in solution. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1508–1516     

光控纳米载体在药物释放中的应用

光敏感的纳米载体因其可从时间和空间上精确地控制药物的释放以实现对肿瘤的高效治疗,近年来逐渐成为生物医学领域的研究热点之一。本文综述了光敏感的纳米载体破裂从而释放出装载的药物的三种机理,主要包括：（1）光致异构化引发的纳米载体形态转变;（2）光反应引发的纳米载体降解;（3）光热引发的纳米载体破裂。本文简单介绍了这三种释放机理,例举了这三种释放机理所对应的光敏感材料,并阐述了其在药物运输、可控释放以及肿瘤治疗中的最新研究进展以及存在的问题,为光敏感纳米载体在生物体系中的应用提供参考,并对今后的发展作了展望。     

葫芦脲作为超分子纳米反应器/催化剂的研究

葫芦脲是近年来获得广泛关注和长足发展的一种新型超分子主体化合物,其刚性的结构、疏水性的空腔及电负性的端口赋予其极为特殊的识别性质--对有机阳离子客体的高选择性和高亲合性。过去的十几年里,学者们利用其独特的性质将其应用在包括从基本的分子识别与组装到复杂的三维材料的制备以及药物传输及缓释等各个领域中。此外,创造性地将葫芦脲分子用于控制化学反应进程则成为了葫芦脲化学又一备受瞩目的研究方向。本文介绍了葫芦脲及其衍生物作为超分子纳米反应器/催化剂的研究工作,重点介绍了近年来国际国内在此领域取得的部分研究成果,主要包括葫芦脲通过主客体作用对反应底物的反应活性的影响,希望能给对葫芦脲介入的化学反应感兴趣的研究人员提供参考。     

Influence of the Acetamide from Acetonitrile Hydrolysis in Acid-Contained Mobile Phase on the Ultraviolet Detection in High Performance Liquid Chromatography

The paper presents the influence of acetamide on ultraviolet detection after generation of acetonitrile by hydrolysis in the presence of trifluoroacetic acid in the HPLC mobile phase. The acetonitrile, with added varying contents of trifluoroacetic acid and water, was determined by GC–MS at various times. The results showed that the concentration of acetamide increased approximately linearly with time. Using a mixed standard sample solution and a model mobile phase of acetonitrile-water-tri-fluoroacetic acid (25:75:0.3, v/v) after 0, 24 and 48 h, the influence of the hydrolyzate acetamide on HPLC detection was investigated at the wavelength of 205–220 nm. The results showed that the limit of detection (LOD) of standard sample lost about 30 % after the mobile phase was placed 48 h. It is suggested that the acid-containing mobile phase was placed no more than 24 h for HPLC trace analysis at the wavelength of 205–220 nm.

     

Ferrofluids Containing Fe3O4 Nanoparticles in Solidified Photoresist Carrier

Ferrofluids, formed by magnetic nanoparticles uniformly dispersed in a liquid carrier, respond to an external magnetic field, which enable the fluid's position by applying a magnetic field. Here, ferrofluids composed of Fe₃O₄ nanoparticles with oleic acid and oleylamine as the surfactant and photoresist, respectively, were prepared. Under an external magnetic field, the movement and the position of ferrofluids and the injection of the fluids into complex shapes were easily achieved. The ferrofluid surfaces were distorted under the magnetic field, and the surface structue was controlled by the applied field strength. Using a photoresist as the liquid carrier, it was possible to solidify the ferrofluids by UV irradiation. The shape and the position of the solid superparamagnetic nanoparticles/polymer composites were also determined by the external magnetic field.     

Synthesis and characterization of insulin-5-Fu conjugate,enabling insulin as multi-drug carrier via dendritic approach

To enable insulin as multi-drug carrier, we designed and synthesized dendritic linker molecule bearing three 5-Fluorouracil residues at the branch ends. The new conjugate showed excellent water solubility. The stabilities under different conditions were investigated. The results showed that the conjugate was a potential prodrug to release free 5-Fu.