In Situ Formation of a Novel Nanocomposite Structure Based on MCM-41 and Polyethylene

M41S materials are prepared by in situ assembly of inorganic precursors and organic template and can be viewed as nanocomposites of the siliceous phase and organic surfactant. Calcination of these precursors gives the M41S materials that have been used to prepare novel nanocomposite structures, in which the organic phase inside the nano-sized pores is isolated by the nano-sized inorganic pore walls. The nanocomposite structures can be formed by in situ polymerization of monomers inside the channels. Polymerization of ethylene takes place inside the nano-sized pores, producing the desired nanocomposite structure. The resulting polyethylene was found to be a mixture of crystalline and amorphous phases.     

基于CdSe/ZnS量子点荧光猝灭法测定硫胺素

以CdSe/ZnS量子点为荧光探针,基于硫胺素(VB1)与CdSe/ZnS量子点间通过静电作用而有效猝灭CdSe/ZnS量子点荧光强度的机制,建立了一种可快速测定VB1的荧光检测方法.在最优实验条件下(pH 7.4,反应时间25 min),硫胺素(VB1)浓度在0.01 ～1 μmol/L时,CdSe/ZnS量子点荧光猝灭变化强度与硫胺素(VB1)浓度呈良好的线性关系:F0/F=0.67cCB1+1.05(R=0.999 2),方法检出限为5.1×10-3 μmol/L,相对标准偏差为1.09％.该方法可用于人体尿样中VB1的快速测定.     

多层核壳CuInS_2/ZnS量子点的有机相合成的研究

有机相反应体系中合成制备CuInS2量子点核壳结构,并对制备出的核以及核壳结构的材料进行表征。XRD结果显示成功合成纯度高、晶形较好的CIS量子点;通过TEM可以观察到量子点形貌以及尺寸的变化;荧光光谱和吸收光谱则清楚表明在反应过程中红移和蓝移情况以及量子效率的明显增加;最后,由光稳定性实验得出包覆了ZnS的CIS量子点稳定性得到提高。     

碳量子点的制备及其在发光二极管中的应用

碳量子点是纳米材料领域一个备受关注的荧光纳米材料,仅近几年里,基于碳量子点的研究,在制备和应用方面均取得了许多突破性的进展。本文简述了碳量子点的优异特性及其合成方法,重点概述了碳量子点的修饰、复合材料的制备以及在发光二极管(LED)应用方面的最新研究进展。以期为碳量子点的发展应用提供思路和参考。     

CdSe与CdSe/ZnS核壳型量子点的制备方法与展望

CdSe及CdSe/ZnS量子点具有特殊的发光性质性质,它们在生物荧光探针、生物芯片、激光器、光电子器件和光催化等领域具有广泛的应用,现在越来越多的研究者更加关注它们在生命科学研究中起到得定性和定量标识生物分子和细胞作用。本文对几种制备CdSe及CdSe/ZnS量子点的方法进行了简单的综述,分别介绍了CdSe的水相、有机相以及绿色合成法,CdSe/ZnS量子点的热注入有机金属法和水相合成法,对这几种方法的优缺点进行了概述,并对其前景做了展望。     

Synthesis of Metal–Organic Frameworks Quantum Dots Composites as Sensors for Endocrine-Disrupting Chemicals

Hazardous chemical compounds such as endocrine-disrupting chemicals (EDCs) are widespread and part of the materials we use daily. Among these compounds, bisphenol A (BPA) is the most common endocrine-disrupting chemical and is prevalent due to the chemical raw materials used to manufacture thermoplastic polymers, rigid foams, and industrial coatings. General exposure to endocrine-disrupting chemicals constitutes a serious health hazard, especially to reproductive systems, and can lead to transgenerational diseases in adults due to exposure to these chemicals over several years. Thus, it is necessary to develop sensors for early detection of endocrine-disrupting chemicals. In recent years, the use of metal–organic frameworks (MOFs) as sensors for EDCs has been explored due to their distinctive characteristics, such as wide surface area, outstanding chemical fastness, structural tuneability, gas storage, molecular separation, proton conductivity, and catalyst activity, among others which can be modified to sense hazardous environmental pollutants such as EDCs. In order to improve the versatility of MOFs as sensors, semiconductor quantum dots have been introduced into the MOF pores to form metal–organic frameworks/quantum dots composites. These composites possess a large optical absorption coefficient, low toxicity, direct bandgap, formidable sensing capacity, high resistance to change under light and tunable visual qualities by varying the size and compositions, which make them useful for applications as sensors for probing of dangerous and risky environmental contaminants such as EDCs and more. In this review, we explore various synthetic strategies of (MOFs), quantum dots (QDs), and metal–organic framework quantum dots composites (MOFs@QDs) as efficient compounds for the sensing of ecological pollutants, contaminants, and toxicants such as EDCs. We also summarize various compounds or materials used in the detection of BPA as well as the sensing ability and capability of MOFs, QDs, and MOFs@QDs composites that can be used as sensors for EDCs and BPA.     

Diagnosis of Prostate Cancer and Prostatitis Using near Infra-Red Fluorescent AgInSe/ZnS Quantum Dots

The link between the microbiome and cancer has led researchers to search for a potential probe for intracellular targeting of bacteria and cancer. Herein, we developed near infrared-emitting ternary AgInSe/ZnS quantum dots (QDs) for dual bacterial and cancer imaging. Briefly, water-soluble AgInSe/ZnS QDs were synthesized in a commercial kitchen pressure cooker. The as-synthesized QDs exhibited a spherical shape with a particle diameter of 4.5 ± 0.5 nm, and they were brightly fluorescent with a photoluminescence maximum at 705 nm. The QDs showed low toxicity against mouse mammary carcinoma (FM3A-Luc), mouse colon carcinoma (C26), malignant fibrous histiocytoma-like (KM-Luc/GFP) and prostate cancer cells, a greater number of accumulations in Staphylococcus aureus, and good cellular uptake in prostate cancer cells. This work is an excellent step towards using ternary QDs for diagnostic and guided therapy for prostate cancer.     

A Novel Carbon Dots/Thermo-Sensitive In Situ Gel for a Composite Ocular Drug Delivery System: Characterization,Ex-Vivo Imaging,and In Vivo Evaluation

We developed a potential composite ocular drug delivery system for the topical administration of diclofenac sodium (DS). The novel carbon dot CD_C-HP was synthesized by the pyrolysis of hyaluronic acid and carboxymethyl chitosan through a one-step hydrothermal method and then embedded in a thermosensitive in situ gel of poloxamer 407 and poloxamer 188 through swelling loading. The physicochemical characteristics of these carbon dots were investigated. The results of the in vitro release test showed that this composite ocular drug delivery system (DS-CD_C-HP-Gel) exhibited sustained release for 12 h. The study of the ex vivo fluorescence distribution in ocular tissues showed that it could be used for bioimaging and tracing in ocular tissues and prolong precorneal retention. Elimination profiles in tears corresponded to the study of ex vivo fluorescence imaging. The area under the curve of DS in the aqueous humor in the DS-CD_C-HP-Gel group was 3.45-fold that in the DS eye drops group, indicating a longer precorneal retention time. DS-CD_C-HP with a positive charge and combined with a thermosensitive in situ gel might strengthen adherence to the corneal surface and prolong the ocular surface retention time to improve the bioavailability. This composite ocular delivery system possesses potential applications in ocular imaging and drug delivery.     

Transferrin-Decorated Niosomes with Integrated InP/ZnS Quantum Dots and Magnetic Iron Oxide Nanoparticles: Dual Targeting and Imaging of Glioma

The development of multifunctional nanoscale systems that can mediate efficient tumor targeting, together with high cellular internalization, is crucial for the diagnosis of glioma. The combination of imaging agents into one platform provides dual imaging and allows further surface modification with targeting ligands for specific glioma detection. Herein, transferrin (Tf)-decorated niosomes with integrated magnetic iron oxide nanoparticles (MIONs) and quantum dots (QDs) were formulated (PEGNIO/QDs/MIONs/Tf) for efficient imaging of glioma, supported by magnetic and active targeting. Transmission electron microscopy confirmed the complete co-encapsulation of MIONs and QDs in the niosomes. Flow cytometry analysis demonstrated enhanced cellular uptake of the niosomal formulation by glioma cells. In vitro imaging studies showed that PEGNIO/QDs/MIONs/Tf produces an obvious negative-contrast enhancement effect on glioma cells by magnetic resonance imaging (MRI) and also improved fluorescence intensity under fluorescence microscopy. This novel platform represents the first niosome-based system which combines magnetic nanoparticles and QDs, and has application potential in dual-targeted imaging of glioma.     

Time- and Spectrally-Resolved Photoluminescence Study of Alloyed CdxZn1−xSeyS1−y/ZnS Quantum Dots and Their Nanocomposites with SPIONs in Living Cells

Magnetic-luminescent composites based on semiconductor quantum dots (QDs) and superparamagnetic iron oxide nanoparticles (SPIONs) can serve as a platform combining visualization and therapy. Here, we report the construction of QD-SPION nanocomposites based on synthesized SPIONs and alloyed QDs (CdxZn1−xSeyS1−y)/ZnS solubilized with L-cysteine molecules. The study of the spectral-luminescence characteristics, the kinetics of luminescence decay show the composite’s stability in a solution. After incubation with HeLa cells, QDs, SPIONs, and their composites form clusters on the cell surface and associate with endosomes inside the cells. Component-wise analysis of the photoluminescence decay of cell-associated QDs/SPIONs provides information about their localization and aggregate status.     

CdS/Chitosan量子点的制备及其光学性能的研究

以壳聚糖(Chitosan)为稳定剂和包裹剂,在水相中合成了CdS/Chitosan量子点,研究了反应时间、壳聚糖用量、反应温度以及镉硫源摩尔比等对其发光性能的影响,并用紫外可见吸收光谱、红外光谱、X-射线粉末衍射等对量子点进行了表征。结果表明,随着反应时间的延长、反应温度的升高、壳聚糖用量的减少、镉硫源摩尔比的增大,量子点的紫外特征吸收峰会发生红移,从而推测量子点的粒径在不断变大。     

In Situ Hydroxyapatite Synthesis Enhances Biocompatibility of PVA/HA Hydrogels

Bone tissue engineering tries to simulate natural behavior of hard tissues. This study aimed to produce scaffolds based on polyvinyl alcohol (PVA) and hyaluronic acid (HA) with hydroxyapatite (HAp) incorporated in two different ways, by in situ synthesis and physical mixing of pre-prepared HAp. In situ synthesis resulted in calcium deficient form of HAp with lower crystallinity. The proliferation of human osteoblast-like cells MG-63 proved to be better in the scaffolds with in situ synthesized HAp compared to those with physically mixed pre-prepared HAp. For scaffolds with PVA/HA/HAp ratio 3:1:2, there was significantly higher initial adhesion (p = 0.0440), as well as the proliferation in the following days (p < 0.001). It seemed to be advantageous improve the properties of the scaffold by in situ synthesizing of HAp directly in the organic matrix.     

In situ synthesis and characterization of polypropylene/polyvinyl acetate‐organophilic montmorillonite nanocomposite

A novel polymer‐nanoclay hybrid nanocomposite based on polyvinyl acetate (PVAc)‐organophilic montmorillonite (OMMT) has been reported via an in situ intercalated polymerization technique. The hybrid material was synthesized by one‐step emulsion polymerization of vinyl acetate in the presence of OMMT using polyvinyl alcohol as the stabilizing agent. The intercalated polymerization was characterized by X‐ray diffraction (XRD). The XRD patterns show that the interlayer spacing of OMMT after polymerization increased from 2.64 to 3.78 nm, indicating that the large macromolecular chain of PVAc was formed in the OMMT interlayer space. The Fourier transform infrared spectrum showed the characteristic absorption of PVAc in the OMMT particles separated from the nanocomposite, and the position of peaks shifted to high wave numbers. This showed that there was an interaction between PVAc and OMMT nanoparticles. A two‐fold blend composed of PVAc‐nano‐OMMT/PP was prepared by the melt‐blending technique. XRD and transmission electron microscopy images of the PVAc‐nano‐OMMT/PP composite further confirmed the formation of a partially delaminated nanocomposite structure. Thermogravimetry results showed that the thermal stability of PVAc‐nano‐OMMT/PP was greater than that of either polypropylene (PP) or Nano‐OMMT/PP blend. PVAc‐nano‐OMMT/PP had better toughness, as the mass fraction of OMMT was 5 wt %. The flame retardancy of PP, Nano‐OMMT/PP, and PVAc‐nano‐OMMT/PP composites was also studied. According to the limiting oxygen index (LOI) data and Cone calorimeter test, the addition of PVAc‐OMMT resulted in higher LOI and lower heat release rate, effective heat of combustion, smoke release course, and better flame retardancy and barrier properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

One‐Pot Fabrication of Poly(ε‐Caprolactone)‐Incorporated Bovine Serum Albumin/Calcium Alginate/Hydroxyapatite Nanocomposite Scaffolds by High Internal Phase Emulsion Templates

In this work, the authors report an effective one‐pot method to prepare poly(ε‐caprolactone) (PCL)‐incorporated bovine serum albumin (BSA)/calcium alginate/hydroxyapatite (HAp) nanocomposite (NC) scaffolds by templating oil‐in‐water high internal phase emulsion (HIPE), which includes alginate, BSA, and HAp in water phase and PCL in oil phase. The water phase of HIPEs is solidified to form hydrogels containing emulsion droplets via gelation of alginate induced by Ca²⁺ ions released from HAp. And the prepared hydrogels are freeze‐dried to obtain PCL‐incorporated porous scaffolds. The obtained scaffolds possess interconnected pore structures. Increasing PCL concentration clearly enhances the compressive property and BSA stability, decreases the swelling ratio of scaffolds, which assists in improving the scaffold stability. The anti‐inflammatory drug ibuprofen can be highly efficiently loaded into scaffolds and released in a sustained rate. Furthermore, mouse bone mesenchymal stem cells can successfully proliferate on the scaffolds, proving the biocompatibility of scaffolds. All results show that the PCL‐incorporated NC scaffolds possess promising potentials in tissue engineering application.

     

ETA‐m‐PAN and its Composite Membrane with High Performance Prepared by In Situ Modification/NIPS Principle

Ethanolamine‐modified polyacrylonitrile (ETA‐m‐PAN) membrane is prepared by in situ modification integrated with a nonsolvent‐induced phase separation method for the first time. The results reveal that both the morphology and the separation performance of the modified membrane change greatly with condition parameters. The membrane formation mechanism is carefully investigated, which is related to the change in the molecular structure and hydrophilic property of ETA‐m‐PAN. The cross‐linked structure leads to the formation of ETA‐m‐PAN spongy membrane. The optimized condition parameters are determined by permeability‐selectivity analysis. Furthermore, the composite membrane with ETA‐m‐PAN as the selective layer is prepared by a dual‐casting method. The obtained membrane shows a good property, flux of 650L m^?2 h^?1 bar^?1, 82% BSA rejection, and 84% water flux recovery ratio. This work demonstrates the great potential of this integrated method for new membrane preparation.     

Novel Polyamide 6/Polystyrene In Situ Microfibrillar Blends Prepared by Anionic Polymerization of ε‐Caprolactam via Reactive Extrusion

In this study, polyamide 6/polystyrene in situ microfibrillar blends are prepared via anionic polymerization of ε‐caprolactam in a twin screw extruder. Scanning electron microscope analysis reveals that microfibrillated PA6 dispersed phase, which is continuous and preferentially oriented parallel to the extrusion direction, is in situ formed within polystyrene (PS) matrix during reactive extrusion at the content PS equal to 30 and 40 wt%. Mechanical properties analysis shows that the yield strength and elongation at break of PA6/PS (70/30 and 60/40) microfibrillar blends are remarkably increased with respect to those of pure PS. Also, the in situ fibrillation mechanisms are investigated by the analysis of morphological evolution. This work demonstrates a facile and efficient route to fabricate the microfibrillar blends with relatively high contents of polymer microfibrils.

     

Preparation and characterization of flame‐retardant melamine cyanurate/polyamide 6 nanocomposites by in situ polymerization

This article focuses on an improved method, i.e., improved in situ polymerization of ε‐caprolactam in the presence of melamine derivatives to prepare flame‐retardant melamine cyanurate/polyamide 6 (MCA/PA6) nanocomposites. The chemical structures of these synthetic flame retardant composites are characterized by Fourier‐transform infrared spectroscopy and X‐ray diffraction. Morphologies, mechanical properties, and thermal properties also are investigated by the use of transmission electron microscopy, mechanical testing apparatus, differential scanning calorimetry, and thermogravimetric analysis, respectively. Through transmission electron microscopy photographs, it can be found that the in situ‐formed MCA nanoparticles with diametric size of less than 50 nm are nanoscaled, highly uniformly dispersed in the PA6 matrix. These nanocomposites, which have good mechanical properties, can reach UL‐94 V‐0 rating at 1.6‐mm thickness even at a relatively low MCA loading level. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

In situ polymerization and characterization of polyamide‐6/silica nanocomposites derived from water glass

Polyamide‐6/silica nanocomposites were prepared via an in situ polymerization route using silicic acid as the precursor of silica, which was extracted from water glass. Scanning electron microscopy observations showed that the silica particles were well dispersed in the polyamide‐6 matrix on the nanometer scale, which demonstrated that this method could effectively avoid agglomeration of the inorganic particles. The coupling agent, (γ‐aminopropyl) triethoxysilane, was added to introduce interfacial interactions between the silica and the polymer matrix, which led to an increased graft of polymer on the silica surface and made the material display higher performance. It was found that the incorporation of the inorganic component significantly increased the melt viscosity, tensile strength, Young's modulus, thermal decomposition temperature, glass transition temperature and Vicat softening temperature of the polyamide‐6 resin. The reinforcement of the silica particles was clearly demonstrated. Copyright © 2004 Society of Chemical Industry