Smart Poly (N-Isopropylacrylamide)-block-Poly (L-Lactide) Nanoparticles for Prolonged Release of Naltrexone

The authors synthesized core-shell smart nanoparticles composed of poly (N-isopropylacrylamide)-b-poly (L-lactide) (PNIPAAm–b-PLA) and developed for narcotic antagonists’ drug-delivery purpose. Micelle structure was verified by ¹H-NMR, FT-IR, and TEM. Effect of drug loading, polymer composition, and temperature on micelles morphology and diameter was investigated. Stimuli-responsive behaviors of these nanoparticles were determined using a three-factor full factorial experiment. Naltrexone was successfully incorporated into the PLA cores. By varying the PLA to PNIPAAm ratio, drug loading content, and release time were changed. Results suggest that smart micelles can be suitable for preparation of sustained release systems.     

以核壳结构聚合物模板合成P(St-co-DEA)/SiO_2杂化粒子

本文采用聚(苯乙烯-co-甲基丙烯酸-N,N-二甲氨基乙酯)[P(St-co-DEA)]核壳纳米粒子为模板,在环境条件下以四甲基硅氧烷(TMOS)为前体,原位可控沉积纳米结构SiO2,合成了具有PSt核和PDEA-SiO2杂化的壳层纳米粒子,将杂化粒子进一步煅烧可得到空心的SiO2纳米微球。采用FT IR、TEM以及DLS对所合成的杂化纳米粒子进行了详细的表征。TEM观察证实了纳米结构SiO2在粒子壳层中的沉积,随着矿化反应的进行,体系形成了具有核壳结构的树莓状纳米粒子。研究表明:杂化粒子的表面粗糙程度及大小可以通过简单改变体系试验参数(如TMOS的用量和矿化时间等)而控制。     

羟基磷灰石涂层的生物仿生法研究进展

羟基磷灰石的生物复合涂层具有很高的外科应用价值.制备羟基磷灰石复合材料的方法有很多种,其中仿生法模仿了自然界生理磷灰石的矿化机制,在类似于人体组织内环境条件的水溶液中自然沉积出磷灰石层.仿生法具有许多其它方法无可比拟的优越性.本文对近年来文献报道中出现的生物仿生法进行了综述,阐述了各种仿生法中包括对基体进行预处理使其表面官能团化,再将基体在模拟体液中浸泡从而使磷灰石自然沉积的模拟生物矿化的4个阶段的工艺过程及其仿生机理.     

生物大分子介导仿生矿化制备磁性纳米粒子的研究进展

相比其他纳米材料,磁铁矿（Fe₃O₄）纳米粒子由于具有磁响应性而被广泛应用于酶固定化、定向给药及核酸提取等方面。不同大小和形状的磁铁矿纳米颗粒可用于不同的领域,如晶体尺寸越小的Fe₃O₄对人体副作用越小,有望用于疾病高效、靶向治疗。近年来,控制Fe₃O₄纳米粒子大小和形貌的新方法研究逐步成为热点。因此,本文回顾了传统的共沉淀制备磁性纳米颗粒的方法,这些方法需要使用有机溶剂或高温等条件控制,介绍了这些方法存在的环境污染和安全性问题。在此基础上,本文深入介绍了近年来出现的一种受自然界生物矿化启发的生物大分子介导的仿生矿化制备磁性纳米粒子的新趋势,综述了生物大分子蛋白质（或多肽）介导的仿生矿化的最新研究进展,阐释了该方法在磁铁矿（Fe₃O₄）纳米粒子的大小和形貌控制方面的优缺点,并对其应用前景及面临的挑战进行了展望。     

Chemical routes in the synthesis of nanomaterials using the sol-gel process

In this Account, we discuss the usefulness of the sol-gel process in the synthesis of materials comprising nanoscale architectures. We describe the processing of semiconducting, metallic, ferroelectric, or scintillating nanoparticles in various oxide matrices. We also discuss the synthesis of some nanoporous oxides and organic-inorganic nanohybrids, including core-shell nanostructures.     

有机基质自组装的计算机模拟及其在仿生合成中的应用进展

利用有机基质的模板作用能仿生合成出性能优异的新型无机材料。计算机模拟是研究有机基质自组装特性、超分子聚集体结构和特性的有效方法。本文简述了仿生技术的基础理论后,对两亲有机分子、有机高分子、生物大分子三类有机基质自组装的计算机模拟研究及其在仿生材料合成中的应用研究进行了综述,最后展望了仿生合成在未来材料化学中的发展趋势和前景。     

Multiresponsive polymeric particles with tunable morphology and properties based on acrylonitrile (AN) and 4-vinylpyridine (4-VP)

We report the synthesis of amphiphilic, pH and magnetic field sensitive polymeric particles obtained from the modification of poly(acrylonitrile-co-4-vinylpyridine) (p(AN-c-4-VP)) core-shell nanoparticles. The magnetic metal nanoparticles were encapsulated in the microemulsion during the polymerization to achieve magnetic-p(AN-c-4-VP)-composites with various morphology. We further chemically modified each component of p(AN-c-4-VP) particles and its composite to tune the hydrophilicity of the particles. Modification of nitrile (hydrophobic) groups to amidoxime (hydrophilic) groups by amidoximation reaction on AN, and quarternization of nitrogen on pyridine ring of 4-VP were carried out to tune the hydrophilicity and the charge of the particles. The modification also performed on magnetic responsive composites after inclusion of separately prepared magnetic Fe₃O₄ nanoparticles. It was further demonstrated that these multiresponsive particles can be used as drug carrier. A nonsteroidal and anti-inflammatory drug Naproxen was used as a model active agent for drug loading and the release studies from (p(AN-c-4-VP) based particles in phosphate buffer solution (pH = 7.4) at ambient temperature.     

“Smart” nanoparticles: Preparation, characterization and applications

We review recent work on the preparation, characterization and application of “smart” microgel particles. A general feature of all systems under consideration here is their ability to react to external stimuli as e.g. the pH or the temperature in the system. Special emphasis is laid on our recent research work on the thermosensitive core-shell microgel particles, which are composed of a PS core and a cross-linked poly(N-isopropylacrylamide) (PNIPA) shell. Work done on these core-shell systems is compared to developments on the investigations of similar systems. A novel synthesis method, namely photo-emulsion polymerization, has been described for the preparation of monodisperse, thermosensitive core-shell particles. Cryogenic transmission electron microscopy (cryo-TEM) has recently been employed to investigate the morphology and the volume transition of the core-shell type microgels. This method furnishes information about the thermosensitive particles that had not been available through other methods employed in previous investigations. Very recently, it has been shown that these core-shell microgels can be used as “nanoreactors” for the immobilization of metal nanoparticles. The metal nanocomposite particles show “smart” catalytic behaviour, inasmuch as the catalytic activity of nanoparticles can be switched on and off through the volume transition that takes place within the thermosensitive shell of the carrier system. We also discuss possible future applications of these systems.     

大分子组装体作用下仿生膜的合成

引　言仿生合成技术是将生物矿化机理引入无机材料合成 ,以有机物的组装体为模板控制无机物的形成 ,制备具有独特显微结构特点的无机材料 ,使材料具有优异的物理和化学性能[1,2 ] .仿生合成材料具有广阔的应用前景———微米级多孔仿生合成材料是极好的隔热、隔声材料 ;具有纳米级精细孔结构的分子筛可根据粒子大小对细颗粒进行准确的分类 ,例如筛选细菌与病毒等 ,用作高渗透通量、高分离精度的纯净水生产装置 ;如果与细小催化剂颗粒相结合 ,这种材料可以实现反应与分离过程的有效耦合 ;仿生合成的磷灰石材料是性能优异的新骨组织构造基架 ,…     

Enhancing Osteoconduction of PLLA-Based Nanocomposite Scaffolds for Bone Regeneration Using Different Biomimetic Signals to MSCs

In bone engineering, the adhesion, proliferation and differentiation of mesenchymal stromal cells rely on signaling from chemico-physical structure of the substrate, therefore prompting the design of mimetic "extracellular matrix"-like scaffolds. In this study, three-dimensional porous poly-L-lactic acid (PLLA)-based scaffolds have been mixed with different components, including single walled carbon nanotubes (CNT), micro-hydroxyapatite particles (HA), and BMP2, and treated with plasma (PT), to obtain four different nanocomposites: PLLA + CNT, PLLA + CNTHA, PLLA + CNT + HA + BMP2 and PLLA + CNT + HA + PT. Adult bone marrow mesenchymal stromal cells (MSCs) were derived from the femur of orthopaedic patients, seeded on the scaffolds and cultured under osteogenic induction up to differentiation and mineralization. The release of specific metabolites and temporal gene expression profiles of marrow-derived osteoprogenitors were analyzed at definite time points, relevant to in vitro culture as well as in vivo differentiation. As a result, the role of the different biomimetic components added to the PLLA matrix was deciphered, with BMP2-added scaffolds showing the highest biomimetic activity on cells differentiating to mature osteoblasts. The modification of a polymeric scaffold with reinforcing components which also work as biomimetic cues for cells can effectively direct osteoprogenitor cells differentiation, so as to shorten the time required for mineralization.     

Methods for Biomimetic Remineralization of Human Dentine: A Systematic Review

This study aimed to review the laboratory methods on biomimetic remineralization of demineralized human dentine. A systematic search of the publications in the PubMed, TRIP, and Web of Science databases was performed. Titles and abstracts of initially identified publications were screened. Clinical trials, reviews, non-English articles, resin-dentine interface studies, hybrid layer studies, hybrid scaffolds studies, and irrelevant studies were excluded. The remaining papers were retrieved with full texts. Manual screening was conducted on the bibliographies of remaining papers to identify relevant articles. A total of 716 studies were found, and 690 were excluded after initial screening. Two articles were identified from the bibliographies of the remaining papers. After retrieving the full text, 23 were included in this systematic review. Sixteen studies used analogues to mimic the functions of non-collagenous proteins in biomineralization of dentine, and four studies used bioactive materials to induce apatite formation on demineralized dentine surface. One study used zinc as a bioactive element, one study used polydopamine, and another study constructed an agarose hydrogel system for biomimetic mineralization of dentine. Many studies reported success in biomimetic mineralization of dentine, including the use of non-collagenous protein analogues, bioactive materials, or elements and agarose hydrogel system.     

仿生合成技术及其应用研究

90年代以来,出现了一种模仿生物矿化中无机物在有机物调制下形成过程的新合成方法－仿生合成,利用仿生合成技术制备的纳米微粒,薄膜,多孔材料等物质具有特殊的物理和化学性能,潜在着广阔的应用前景,这使得无机材料的仿生合成技术已成为材料化学研究的前沿和热点。     

仿生合成在无机粉体制备技术中的应用

无机粉体以其优异的性能被广泛应用各个领域。本文概要介绍了仿生合成方法在无机粉体制备技术中的应用及其发展现状。仿生合成具有的诸多优点,使无机材料的仿生合成技术成为无机材料化学的研究前沿和热点。     

Synthesis,characterization of biomimetic phosphorylcholine‐bound chitosan derivative and in vitro drug release of their nanoparticles

Novel water‐soluble biomimetic phosphorylcholine (PC)—bound chitosan derivatives (N‐PCCs) with different degree of substitution (DS) via a phosphoramide linkage between glucosamine and PC were synthesized through Atherton‐Todd reaction under the mild conditions, and structurally characterized by ¹H‐NMR, Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), X‐ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Their DS ranged from ～ 16 to ～ 42 mol % based on the ¹H‐NMR spectra. All these N‐PCCs with decreased crystallization showed excellent solubility in the aqueous solutions within a wide pH range (1–12). DSC and TGA results revealed that the thermal stability of N‐PCCs decreased with the increase of DS value. Further, N‐PCCs nanoparticles could be still formed in a spherical shape similar to chitosan nanoparticles by ionic gelation technique, observed by atomic force microscopy (AFM). Dynamic light scattering (DLS) results suggested that the zeta potential value of N‐PCCs nanoparticles decreased with the DS value increasing. Using 5‐fluorouracil (5‐Fu) as a model drug, in vitro drug release studies indicated that N‐PCCs nanoparticles exhibited a similar prolonged release profile as chitosan nanoparticles. The results suggested that N‐PCCs nanoparticles could be used as promising nanocarriers for drug delivery applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Biomimetic Multienzyme Complexes Based on Nanoscale Platforms

Inspired by the widely present multienzyme complexes in nature that enable highly cooperative catalytic mechanisms, we designed a biomimetic dual‐functionalized nanoparticle‐based platform for colocalizing multiple enzymes. The use of nanoscale materials together with a novel sequential colocalization approach with two model enzymes [glucose oxidase (GOX) and horseradish peroxidase] resulted in a 100% increase in the overall conversion rate compared to the equivalent amount of free enzymes in solution and a physical mixture of individual immobilized enzymes on nanoparticles. GOX is an important enzyme used in glucose biosensors for diagnostics. Colocalizing GOX with peroxidase allows for colorimetric visualization of the peroxide formed that enables monitoring glucose levels in solution. This platform can be readily applicable to other multienzyme systems as well. © 2012 American Institute of Chemical Engineers AIChE J, 59: 355–360, 2013     

金属卟啉类仿生催化剂的合成、构效关系及在催化氧化碳氢化合物中的应用

综述了金属卟啉类仿生催化剂的理论基础、合成、构效关系及其在仿生催化氧化烃类绿色合成有机中间体和产品方面的研究进展。重点报道了该课题组和郭灿城课题组近年来在金属卟啉类仿生催化剂的分子设计、合成方法、构效关系及其在催化空(氧)气选择氧化各种芳烃侧链、环烷烃绿色合成芳醛、芳酸、环己酮、己二酸等重要有机中间体及精细化学品方面的研究成果,特别是由湖南大学郭灿城教授与中石化联合开发的完全拥有我国知识产权的仿生催化空气氧化环己烷(80～140℃,0.5～0.8MPa下反应2h)制取环己醇及环己酮的新技术,已于2003年首次成功地实现了产业化,其中,环己烷的转化率可达8%～10%,环己醇及环己酮的选择性可达90%。最后,对仿生催化技术的发展方向及应用前景进行了展望。引用文献57篇。     

Controlled geometry fabrication of polydimethylsiloxane nanofibers for biomimetics

The ability to have control of fabricated structures on the nanometer size scale is essential in interfacing inorganic technologies with biological systems in many scientific areas including biomimetics and cell topology studies. Here, we developed a simple and efficient method to produce polydimethylsiloxane (PDMS) nanofibers with controlled aspect ratios that could be used in biological studies. As PDMS is a well studied polymer system, this structure would enable a variety of diverse applications. A template synthesis technique was used to create the fibers by molding a polymer solution into an alumina membrane. The pressure and the template surface chemical characteristics were controlled to enable the easy creation of geometric configurations with up to a 30‐fold range of aspects ratios through the use of the same porous alumina template. These fibers can be also used in producing biomimetic synthetic column structures that are found in biological systems such as spider hairs and gecko feet. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis and optimization of dopamine hydrochloride functionalized palygorskite and their application in protective coatings on water saturated surface of concrete

The synthesis process of dopamine hydrochloride functionalized palygorskite (Pal) nanoparticles (Pal@PDA) is optimized by adjusting the mass ratio of them. The optimal preparation technology of the Pal@PDA is determined by scanning electron microscopy and comparing the adhesive strength between the biomimetic protective coatings and dry and water saturated concrete surface. When the mass ratio of dopamine hydrochloride to Pal is 1:4, the prepared Pal@PDA does not contain excess polydopamine (PDA) nanoparticles and the coatings incorporating the Pal@PDA have the highest adhesive strength on dry and water saturated concrete surface at the same conditions. Compared with the pure epoxy primer, the adhesive strength between the epoxy primer incorporating 5 wt% Pal@PDA and the water saturated concrete surface increases by 25.69% (from 3.282 to 4.125 MPa). Furthermore, the Pal@PDA is embedded into pure epoxy resin to prepare the biomimetic resin composites, the tensile strength and compressive strength of the composites incorporating 5 wt% Pal@PDA are 91.20% and 34.77% higher than that of pure epoxy resin, respectively. Further studies confirm that the active groups on the Pal@PDA surface form the stable covalent and non-covalent bonds with epoxy primer and the water saturated concrete surface, which is the major mechanism of improving interfacial adhesion.     

Functionalized nanostructures with application in regenerative medicine

In the last decade, both regenerative medicine and nanotechnology have been broadly developed leading important advances in biomedical research as well as in clinical practice. The manipulation on the molecular level and the use of several functionalized nanoscaled materials has application in various fields of regenerative medicine including tissue engineering, cell therapy, diagnosis and drug and gene delivery. The themes covered in this review include nanoparticle systems for tracking transplanted stem cells, self-assembling peptides, nanoparticles for gene delivery into stem cells and biomimetic scaffolds useful for 2D and 3D tissue cell cultures, transplantation and clinical application.     

Facile fabrication of hollow mesoporous bioactive glass spheres: From structural behaviour to in vitro biology evaluation

Bone defects accompanied by infection or inflammation can significantly delay the healing process. To simultaneously achieve controlled release of local antibiotics for infection control and bone healing, bone-implantable delivery systems have been considered as a promising strategy. This study aims to improve drug loading capacity of bone-implantable delivery systems by introducing hollow structure mesoporous bioactive glass nanospheres (HMBGs) through a sol–gel process. Particularly, such core–shell bimodal-porous structured nanoparticles were prepared through a sacrificing template using cetyltrimethylammonium bromide (CTAB) as surfactant. It was found that varying the amount of CTAB during the synthesis process is a simple and effective approach for tuning the particle size, morphology, and structure of HMBGs. For in vitro drug release, HMBGs could sustain storage and release of vancomycin hydrochloride (VAN) via diffusion-controlled mechanism, thereby inhibiting the bacteria growth in the subsequent bacterial study. Moreover, HMBGs incorporated with VAN provided a biomimetic microenvironment favored by cell adhesion and proliferation. These findings support the compatibility of HMBG nanoparticles with antibiotics and their potential application in the treatment of infectious bone defects.