With an increasing demand for seawater desalination, fabricating photothermal materials with low cost, high photothermal conversion efficiency, and excellent mechanical stability is necessary but remains challenging. In this work, reduced graphene oxide nanosheets (RGOs) and silver nanoparticles (AgNPs) doped polyvinyl alcohol (PVA) sponges (RGOs-AgNPs/PVA) are fabricated by the mechanical foaming and impregnation reduction method, which combine the flexible porous structure of PVA sponges with the photothermal properties of RGOs-AgNPs. The incorporation of RGOs-AgNPs enhances the surficial hydrophobicity and reduces the accumulation of water on the surface, and the photothermal synergistic effect of RGOs-AgNPs enhances the water evaporation rate. The results showed that the evaporation rate of RGOs-AgNPs/PVA was 2.09 kg m−2 h−1 and the photothermal conversion efficiency was 94.2 % under standard sunlight intensity of 1 sun (1.0 kW m−2). Furthermore, the long-term stability and effective desalination capability of the RGOs-AgNPs/PVA solar evaporation device offer a potential opportunity for massive seawater desalination. Therefore, this work shows the prospect of combining flexible porous sponges with photothermal materials for practical solar evaporation.

BACKGROUND: Polysaccharide hydrogel is one of the most important materials for the colon target drug release system. However, the degradation time of polysaccharide hydrogel is much longer than the retention time in the colon. The drugs are expelled from the body before being released. OBJECTIVE: In order to match the degradation of drug carriers and their retention time in the colon, a rapidly degradable konjac glucomannan (KGM) hydrogel was designed for colon target drug release. METHODS: A crosslinker containing azo bond, olsalazine, was used to prepare the rapidly degradable KGM hydrogel. The degradation and drug release of the hydrogels with different crosslinking densities in the normal buffer and the human fecal medium were studied to evaluate the efficiency of colon drug release. RESULTS: More than 50% of the KGM hydrogel by weight was degraded and more than 60% of the 5-fluorouracil (5-Fu) was released within 48 h in 5% w/v human fecal medium. CONCLUSION: The drug was released more rapidly in a simulated colon environment than in a normal buffer. Furthermore, the drug release was controlled by the degradation of the hydrogel. The KGM hydrogel containing azo crosslinker has great potential for colon drug release.

With an increasing demand for seawater desalination, fabricating photothermal materials with low cost, high photothermal conversion efficiency, and excellent mechanical stability is necessary but remains challenging. In this work, reduced graphene oxide nanosheets (RGOs) and silver nanoparticles (AgNPs) doped polyvinyl alcohol (PVA) sponges (RGOs-AgNPs/PVA) are fabricated by the mechanical foaming and impregnation reduction method, which combine the flexible porous structure of PVA sponges with the photothermal properties of RGOsAgNPs. The incorporation of RGOs-AgNPs enhances the surficial hydrophobicity and reduces the accumulation of water on the surface, and the photothermal synergistic effect of RGOs-AgNPs enhances the water evaporation rate. The results showed that the evaporation rate of RGOs-AgNPs/PVA was 2.09 kg m- 2 h-1 and the photothermal conversion efficiency was 94.2 % under standard sunlight intensity of 1 sun (1.0 kW m- 2). Furthermore, the long-term stability and effective desalination capability of the RGOs-AgNPs/PVA solar evaporation device offer a potential opportunity for massive seawater desalination. Therefore, this work shows the prospect of combining flexible porous sponges with photothermal materials for practical solar evaporation.

磁性吸附剂是将传统吸附剂磁化后得到的复合材料.本文综述了几种常用的磁性吸附剂的制备方法,特点和存在的问题.这种新型吸附剂吸附容量高,可以用磁力回收或去除,已经在废水重金属离子处理上显示出良好的效果,具有很好的商业应用前景.

Magnetic nanoparticles have been widely developed as vectors in targeting drug and gene delivery. Disulfide-containing polyethylenimine derivative- (SSPEI-) functionalized magnetic carbon nanotubes (CNTs/Fe 3 O 4 -SSPEI) were synthesized as gene vector. Fourier transform infrared, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis were used to characterize CNTs/Fe 3 O 4 -SSPEI nanoparticles. The magnetic nanoparticles displayed typical superparamagnetic behavior and excellent dispersibility in water. Plasmid DNA could be bound by CNTs/Fe 3 O 4 -SSPEI to form the complexes. The sizes of complexes are about 400 nm, and the zeta potentials are positive at the w/w ratio over 6. CNTs/Fe 3 O 4 -SSPEI nanoparticles displayed higher transfection activity than did PEI (25 kDa), whereas the cytotoxicity was rather lower. Moreover, the transfection efficiency was further increased with the assistance of an external magnetic field. These results indicate that CNTs/Fe 3 O 4 -SSPEI nanoparticles would be a promising vector in targeted gene delivery.

Carbon nanotubes (CNTs) are emerging transporters for delivery of gene and drug. The degradable polycation functionalized CNTs (CNTs-HDDAPEI) were fabricated by grafting ester bond-containing polyethyleneimine (HDDAPEI). Fourier transform infrared spectroscopy, Raman spectrum, transmission electron microscopy and thermogravimetric analysis were used to characterize the degradable polyethyleneimine decorated CNTs. Compared with pristine CNTs, the CNTs-HDDAPEI displayed better dispersability and stability in water.

根据E+材料化学专业特点,对《材料研究与测试方法》课程的教学内容、教学方法、教学手段等进行了分析,并就教学过程中如何改革、如何提高本课程的教学质量以达到E+材料化学专业的培养目标提出一些看法.

Novel functionalized carbon nanotubes (CNTs) were prepared by grafting disulfide-containing polyethyleneimine (SSPEI) to CNTs. The SSPEI were synthesized by Michael addition between cystamine bisacrylamide and low molecular weight branched 1.8 kDa PEI. Three SSPEI grafted carbon nanotubes (CNTs-SSPEI) were successfully prepared through grafting SSPEI to CNTs. The grafted ratios were 32.26%, 43.11%, and 51.50%, respectively. Moreover, the grafted ratio could be tuned by adjusting the CNTs/SSPEI ratio during the process of preparation. The CNTs-SSPEI was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The CNTs-SSPEI showed better dispersability and stability in water than CNTs. In addition, the SSPEI on the surface of CNTs-SSPEI could be degraded in the presence of dithiothreitol.

Professional English and Information Technology of Materials Chemistry is a very professional and practical course. Base on the characteristics of materials chemistry of Wuhan institute of technology and the requirements of this course, some good reformation and practice were studied. The main contents included the selection of suitable teaching material, the seeking of popular teaching approach and the research of useful practice project, which became to a unique teaching system.

Vascular endothelial leukocyte adhesion molecules, such as E-selectin, are acutely upregulated in myocardial ischemia/reperfusion and are thus “ischemic memory” biomarkers for recent cardiac ischemia. We sought to develop an ultrasound molecular imaging agent composed of microbubbles (MBs) targeted to E-selectin to enable the differential diagnosis of myocardial ischemia in patients presenting with chest pain of unclear etiology. Biodegradable polymer MBs were prepared bearing a peptide with specific human E-selectin affinity (MBESEL). Control MBs had scrambled peptide (MBCTL) or nonspecific IgG (MBIgG). MBESEL adhesion to activated rat endothelial cells (ECs) was confirmed in vitro in a flow system and in vivo with intravital microscopy of rat cremaster microcirculation. Ultrasound molecular imaging of recent myocardial ischemia was performed in rats 4 hours after transient (15 minutes) coronary occlusion. MBESEL adhesion was higher to inflamed versus normal ECs in vitro; there was no difference in MBCTL or MBIgG adhesion to inflamed versus normal ECs. There was greater adhesion of MBESEL to inflamed versus noninflamed microcirculation and minimal adhesion of MBCTL or MBIgG under any condition. Ultrasound imaging after injection of MBSEL demonstrated persistent contrast enhancement of the previously ischemic region. Videointensity in postischemic myocardium after MBESEL was higher than that in the nonischemic bed (11.6 ± 2.7 dB vs 3.6 ± 0.8 dB, p < .02) and higher than that after MBCTL (4.0 ± 1.0 dB, p < .03) or MBIgG (1.7 ± 0.1 dB, p < .03). MBs targeted to E-selectin via a short synthetic peptide with human E-selectin binding affinity enables echocardiographic detection of recent ischemia, setting the stage for clinical myocardial ischemic memory imaging to identify acute coronary syndromes.

As a means to stimulate wound healing, a hollow fiber membrane system might be placed within a wound bed to provide local and externally regulated controlled delivery of regenerative factors. After sufficient healing, it would be desirable to triggerably degrade these fibers as opposed to pulling them out. Accordingly, a series of enzymatically degradable thermoplastic elastomers was developed as potential hollow fiber base material. Polyurethane ureas (PUUs) were synthesized based on 1, 4-diisocyanatobutane, polycaprolactone (PCL) diol and polyethylene glycol (PEG) at different molar fractions as soft segments, and collagenase-sensitive peptide GGGLGPAGGK-NH2 as a chain extender (defined as PUU-CLxEGy-peptide, where x and y are the respective molar percents). In these polymers, PEG in the polymer backbone decreased tensile strengths and initial moduli of solvent-cast films in the wet state, while increasing water absorption. Collagenase degradation was observed at 75% relative PEG content in the soft segment. Control PUUs with putrescine or nonsense peptide chain extenders did not degrade acutely in collagenase. Conduits electrospun from PUU-CL25EG75-peptide and PUU-CL50EG50-peptide exhibited appropriate mechanical strength and sustained release of a model protein from the tube lumen for 7 days. Collapse of PUU-CL25EG75-peptide tubes occurred after collagenase degradation for 3 days. In conclusion, through molecular design, synthesis and characterization, a collagenase-labile PUU-CL25EG75-peptide polymer was identified that exhibited the desired traits of triggerable lability, processability, and the capacity to act as a membrane to facilitate controlled protein release.

Restoration of functional endothelium is a requirement for preventing late stent thrombosis. We propose a novel method for targeted delivery of stem cells to a site of arterial injury using ultrasound-generated acoustic radiation force. Mesenchymal stem cells (MSCs) were surface-coated electrostatically with cationic gas-filled lipid microbubbles (mb-MSC). mb-MSC was characterized microscopically and by flow cytometry. The effect of ultrasound (5 MHz) on directing mb-MSC movement toward the vessel wall under physiologic flow conditions was tested in vitro in a vessel phantom. In vivo testing of acoustic radiation force-mediated delivery of mb-MSCs to balloon-injured aorta was performed in rabbits using intravascular ultrasound (1.7 MHz) during intra-aortic infusion of mb-MSCs. Application of ultrasound led to marginalization and adhesion of mb-MSCs to the vessel phantom wall, whereas no effect was observed on mb-MSCs in the absence of ultrasound. The effect was maximal when there were 7±1 microbubbles/cell (n=6). In rabbits (n=6), adherent MSCs were observed in the ultrasound-treated aortic segment 20 min after the injection (334±137 MSCs/cm(2)), whereas minimal adhesion was observed in control segments not exposed to ultrasound (2±1 MSCs/cm(2), p<0.05). At 24 h after mb-MSC injection and ultrasound treatment, the engrafted MSCs persisted and spread out on the luminal surface of the artery. The data demonstrate proof of principle that acoustic radiation force can target delivery of therapeutic cells to a specific endovascular treatment site. This approach may be used for endoluminal cellular paving and could provide a powerful tool for cell-based re-endothelialization of injured arterial segments.

Background: Human mesenchymal stem cell (hMSC) therapy is promising for cardiac repair. Clinical translation requires a method to serially track cell distribution in vivo. We have previously shown that polylactide microbubbles (MB) are internalized by hMSC, persist in the cytoplasm, and allow ultrasound (US) imaging of intramuscularly injected stem cells in mice, but only up to 4 hr at 37°C. We sought to design a more durable MB for prolonged US cell tracking and validated our method against in vivo bioluminescence imaging (BLI). Methods: Nitrogen gas polymer MB with a polycaprolactone and albumin double layer shell were synthesized. MB acoustic activity was measured in a water tank (Contrast Pulse Sequencing, 7MHz) after synthesis (Day 0) and 7 day storage at 37°C. Cultured hMSC expressing luciferase gene were incubated with MB. MB uptake was studied by confocal microscopy. MB-hMSC complexes or control hMSC were lifted, washed, and re-suspended for in vitro US imaging or in vivoinjection (INJ) (0.5-1.0 x...

Coronary stent placement and angioplasty may lead to vascular injury such as postprocedural stent thrombosis and restenosis. Mesenchymal stem cells (MSCs) have been reported to participate in effective restoration of functional endothelium following vascular injury. Our group has recently investigated a new technique for the delivery of MSCs to a site of arterial injury which involved surface-coating MSCs with cationic lipid microbubbles (MB) and directing them to target areas using acoustic radiation force (ARF). The objective of this study was to characterize ultrasound parameters for effective MSC delivery through in vitro experiments in which MB-labeled MSCs flowing through a phantom vessel were radially displaced towards the vessel wall using ARF applied with an intravascular ultrasound catheter driven at varying acoustic pressures and duty cycles. Experimental data indicated that MSC radial velocity was linearly related to the time-averaged ultrasound intensity up to 0.83 W/cm2. Experimental data agreed with model predictions only up to this intensity level possibly due to MB destruction before the MB-MSC complexes reached the target area at high acoustic pressures. MSC adhesion to the phantom vessel wall increased with the time-averaged ultrasound intensity up to 1.65 W/cm2, after which further adhesion did not occur. Using higher time-averaged ultrasound intensities may not substantially benefit the adhesion of complexes to the target vessel wall, but could cause undesirable biological effects such as heating to the MB-MSC complexes and surrounding tissue.

Biodegradable amphiphilic graft copolymers with different compositions were synthesized by grafting poly(l-lactide) (PLLA) sequences onto a water-soluble poly-α,β-[N-(2-hydroxyethyl)-l-aspartamide] (PHEA) backbone. The critical micelle concentration (CMC) of the graft polymers was determined by fluorescence probe technique. Using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, the graft polymers were proved to have low cytotoxicity. Based on the specific physicochemical property of the graft copolymers, submicron sized microsphere drug delivery systems were prepared by a very convenient “ultrasonic dispersion method”, which did not involve toxic organic solvents. The drug-loaded microspheres had a regular spherical shape with a narrow size distribution. A hydrophobic drug, prednisone acetate, was encapsulated into polymeric microspheres and the in vitro drug release was studied.

A convenient and effective 'ultrasonic dispersion method' was used to fabricate vector/DNA complexes encapsulated microspheres. Polyamidoamine (PAMAM) dendrimer/DNA complexes protected by a water-soluble polymer, poly-alpha,beta-[N-(2-hydroxyethyl)-L-aspartamide] (PHEA), were encapsulated in a polymer film mainly composed of cholic acid functionalized star poly(DL-lactide), which degraded through surface erosion mechanism with a fast degradation rate. The PAMAM/DNA complexes encapsulated polymer film was then immersed in ethanol and ultrasonicated to afford the microspheres. The in vitro gene transfections showed PAMAM/DNA complexes protected by PHEA exhibited a much higher transfection activity compared with PAMAM/DNA complexes without the protection by PHEA. The expressions of pGL3-Luc in HEK293 cells could be effectively mediated by the polymer film and microspheres with the presence of PHEA. The ultrasonic dispersion method, which did not involve toxic organic solvents, could keep the bioactivity of DNA and offer good control over the size of microspheres.

Background: Exogenous delivery of reparative cells is a promising new approach to treating cardiovascular disease. Clinical application of cell therapies is limited by a lack of imaging methods for...

Gene therapy shows great promise to treat both acquired and inherited diseases.Numerous gene delivery systems based on viral and nonviral vectors have been developed to protect plasmid DNA and facilitate cell binding and internalization.Nevertheless,it is still a challenge to deliver DNA to target cell population and particular location by injection or systematic delivery due to the immune responses and DNA complex aggregation,degradation,and clearance from the tissue.Polymers loaded with gene or vector/gene complexes can realize the controlled release of gene delivery systems and direct gene delivery to target tissues.This technique,known as substrate-mediated transfection,overcomes the extracelluar barriers of gene delivery,sustains the gene release,decreases the toxicity and consequently improves the gene transfection efficiency.Most commonly,the polymers for the controlled release of gene delivery systems are biodegradable polymers.Using these polymers,a variety of formulations of controlled release systems,including nanoparticles,microspheres,implantable matrices and scaffolds,can be fabricated.This review focuses on the recent developments in the polymers used for the controlled release of gene delivery systems,with emphasis on their applications in gene therapy and tissue engineering.These polymers are classified as natural polymers and their derivatives such as collagen,atelocollagen,gelatin,fibrin,glycosaminoglycans,chitosan,alginate,and agarose,and synthetic polymers including poly(lactide-co-glycolide),poly(lactic acid),functionalized poly-(lactic acid),poly(orthoester)s,poly(β-amino ester)s,polyanhydrides,polyurethanes and poly(ethylene-co-vinylacetate).Looking to the future,through exquisite adjusting of the chemical and physical characteristics of the polymers,optimally engineered properties may be created to gain greater control over gene expression and cell growth.

Background To overcome the extracellular barriers in gene delivery and direct gene delivery to target tissues, substrate-mediated transfection, which sustains the release of naked DNA or vector/DNA complexes, and also supports cell growth, has been developed.Methods In the present Study, polyamidoamine (PAMAM) dendrimer/DNA complexes encapsulated functional biodegradable polymer films for substrate-mediated gene delivery were prepared. To maintain the activity of DNA during dehydration, the dendrimer/DNA complexes were encapsulated in a water soluble polymer, poly alpha,beta-[N-(2-hydroxyethyl)-(L)-aspartamide], and then deposited on or sandwiched in functional polymer films with a fast degradation rate to mediate gene transfection. The in vitro gene transfections of pGL3-Luc and pEGFP-C1 plasmids in HEK293 cells mediated by different films were studied. For comparison, the transfection mediated by the film fabricated by conventional linear poly ((DL)-lactide) was also investigated.Results The expression of pGL3-Luc and pEGFP-C1 plasmids could effectively be mediated by the PAMAM/DNA complexes deposited or sandwiched polymer films, with transfection efficiencies comparable to that of solution-based transfections. The cells on the functionalized star ply((DL)-lactide) film exhibited much higher gene expression compared to the cells on the conventional linear ploy((DL)-lactide) film because the fast degradation rate of star poly ((DL)-lactide) facilitated the access of PAMAM/DNA complexes for the cells seeded on the film. In addition, the films did not exhibit any additional cytotoxicity to the cells during the degradation and transfection.Conclusions The fast degrading functional polymer has great potential for localized transfection. Copyright (C) 2008 John Wiley & Sons, Ltd.