2013 Volume 31 Issue 9

CAPABILITY OF DNA-FUELED MOLECULAR MACHINE IN TUNING ASSOCIATION RATE OF DNA-FUNCTIONALIZED GOLD NANOPARTICLES
Ting-jie Song , Hao-jun Liang
2013, 31(9): 1183-1189  doi: 10.1007/s10118-013-1319-3
[Abstract](584) [FullText HTML] [PDF 0KB](0)
Abstract:
The capability of our newly developed DNA-machine-driven strategy in tuning the association rate of DNA-AuNPs was compared with that of linker-addition strategy which has potential practical applications in different fields. The new established strategy shows its superiority to the linker-addition strategy in tuning the association rate of DNA-AuNPs in both pre-incubation treatment and non-incubation treatment conditions since its two components (a complex and a catalyst-oligonucleotide) can be individually optimized to make the machine run at an optimal rate. This strategy will provide a more convenient and flexible option in designing an oligonucleotide detection system and building a complex and versatile device.
BIOPOLYMER BASED NANO-DELIVERY SYSTEMS FOR ENHANCING BIOAVAILABILITY OF NUTRACEUTICALS
Bing Hu , Qing-rong Huang
2013, 31(9): 1190-1203  doi: 10.1007/s10118-013-1331-7
[Abstract](617) [FullText HTML] [PDF 0KB](0)
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Recently, there has been an increasing interest in the development of efficient food-grade oral nano-delivery systems for encapsulation, protection and target delivery of nutraceuticals to enhance their bioavailability, further to prevent disease and promote human health and well-being. Food proteins represent promising candidates for efficient nutraceutical nanocarriers due to their exceptional characteristics, namely biodegradability, nonantigenicity, high nutritional value, abundant renewable sources and extraordinary binding capacity to various nutraceuticals. In addition, their biocompatibility, biodegradability, low toxicity, low cost, and non-starch polysaccharides possess many favourable characteristics such as stability in the harsh gastric environment, resistance to digestive enzymes, and mucoadhesiveness to intestinal mucosal surface. This review describes the design and formation of nanoscaled delivery systems for nutraceuticals using food-grade proteins (including peptides), polysaccharides and their associative complexes. The toxicity and cellular uptake fate of the nanostructures, as well as their effects on the intestinal absorption of the encapsulated nutraceuticals were also discussed.
SOME KEY ORDERED MACROPOROUS COMPOSITES
Jian-hua Rong , Li-jun Ji , Zhen-zhong Yang
2013, 31(9): 1204-1217  doi: 10.1007/s10118-013-1324-6
[Abstract](629) [FullText HTML] [PDF 0KB](0)
Abstract:
This review summarizes recent progress of the ordered macroporous composites with the opals and inverse opal structure. Synthesis and performance of the composites are emphasized. Composition of the ordered composites is tunable ranging within metal, metal alloy, metal oxide, polymer, carbon and hydrogel. The ordered structure gives brilliant color effects, which is useful for sensors and photonic crystals. The interconnected macroporous structure provides easiness for mass transportation and species culturing.
PHASE BEHAVIOR OF CHARGE STABLIZED COLLOID DISPERSION WITH ADDED WATER SOLUBLE POLYMERS
Jia-xue Liu , Yong-feng Men
2013, 31(9): 1218-1224  doi: 10.1007/s10118-013-1308-6
[Abstract](615) [FullText HTML] [PDF 0KB](0)
Abstract:
Demixing and colloidal crystallization in the mixture of charge stabilized colloidal poly(methyl methacrylate) particles and soluble poly(ethylene oxide) were investigated by means of synchrotron small-angle X-ray scattering (SAXS) technique. Phase diagram of the mixture was obtained based on visual inspection and SAXS results. The phase behavior is determined as a function of the concentration of the polymer as well as the volume fraction of the colloidal particles. The system shows a one phase region when the concentration of the polymer is low, whereas a two-phase region is present when the concentration of the polymer is larger than a critical concentration at certain volume fraction of the colloids. Interestingly, a face centered cubic colloidal crystalline structure was formed under certain conditions, which has been rarely observed in experiments of colloid-polymer mixtures with competing interactions.
SIMULATION STUDY OF CO-ASSEMBLY OF ABC TRIBLOCK COPOLYMER/NANOPARTICLE INTO MULTICOMPARTMENT HYBRIDS IN SELECTIVE SOLVENT
Jie Cui , Wei Li , Wei Jiang
2013, 31(9): 1225-1232  doi: 10.1007/s10118-013-1323-7
[Abstract](589) [FullText HTML] [PDF 0KB](0)
Abstract:
Co-assembly of ABC linear triblock copolymer/nanoparticle into bump-surface multicompartment hybrids in selective solvent was studied through self-consistent field theory (SCFT) simulation. Results from three-dimensional SCFT simulation showed that the hybrid morphology depended on the length and number of grafted chains, whereas the number and shape of bumps relied on nanoparticle size. Moreover, the simulation results showed that the length and number of grafted chains had equivalent effect on hybrid morphology. Calculated results indicated that entropy was a more important factor than enthalpy in the co-assembly.
SYNTHESIS AND PROPERTIES OF BIFUNCTIONAL MAGNETIC-OPTICAL NANOMATERIALS: Fe2O3@PDMAEMA-CAPPED II-VI SEMICONDUCTOR QUANTUM DOTS NANOCOMPOSITES
Na-na Zhao , Wei Nie , Jun Mao , Wei-cai Wang , Xiang-ling Ji
2013, 31(9): 1233-1241  doi: 10.1007/s10118-013-1318-4
[Abstract](596) [FullText HTML] [PDF 0KB](0)
Abstract:
A facile route to synthesize a new type of multifunctional nanocomposites is reported. Here, PDMAEMA (poly[2-(dimethylamino)ethyl] methacrylate) is a key macromolecule serving as a bridge between magnetic Fe2O3 nanoparticles and luminescent quantum dots. Both Fe2O3 nanoparticles and II-VI semiconductor quantum dots with a narrow size distribution are synthesized through a two-phase thermal approach. Subsequently, the atom transfer radical polymerization (ATRP) technique was applied to prepare magnetic Fe2O3@PDMAEMA core-shell nanoparticles. The thickness of PDMAEMA shell can be easily controlled by adjusting the reaction time. Finally, the ligand exchange method was exploited to modify II-VI quantum dot with amine-containing polymer of PDMAEMA, which led to quantum dot securely bound by Fe2O3@PDMAEMA core-shell nanoparticle to form a multifunctional nanocomposite. The resulting nanocomposite remains variable emission by tuning the II-VI semiconductor type and particle size and shows Hc at 49 kA/m and Tb at 16 K from Fe2O3 nanoparticles. The self-assembled behavior for the resulting samples is also discussed.
SELF-ASSEMBLY OF LINEAR ROD-COIL MULTIBLOCK COPOLYMERS
Ying-dong Xia , Ji-zhong Chen , Tong-fei Shi , Li-jia An
2013, 31(9): 1242-1249  doi: 10.1007/s10118-013-1322-8
[Abstract](623) [FullText HTML] [PDF 0KB](0)
Abstract:
The self-assembly of the linear rod-coil multiblock copolymers is studied by applying self-consistent-field lattice techniques in a three-dimensional (3D) space. Compared to the copolymer with one rod, the copolymer with more rods (mrod 2) exhibits rich order-order phase transitions with increasing temperature, where the ordered morphology changes from strips to perforated lamellae and finally to lamellae. In addition, taking the copolymer with mrod = 2 as a representative, we further study the effects of the volume fractions of the rods, the spacer coils and the end coils on the phase behaviors respectively, by which the detailed self-assembled mechanism of the linear rod-coil multiblock copolymers is revealed. Our results are expected to provide guidance for the design of the rod-coil materials.
DEVIATIONS FROM BULK MORPHOLOGIES IN THIN FILMS OF BLOCK COPOLYMER/ADDITIVE BINARY BLENDS
Xin-yu Wei , Wei-yin Gu , Xiao-bo Shen , Joseph Strzalka , Zhang Jiang , Thomas P Russell
2013, 31(9): 1250-1259  doi: 10.1007/s10118-013-1320-x
[Abstract](609) [FullText HTML] [PDF 0KB](0)
Abstract:
Deviations from bulk morphologies in thin films of binary blends of alkyne-functionalized diblock copolymer poly(ethylene oxide)-block-poly(n-butyl methacrylate-random-propargyl methacrylate) (PEO-b-P(nBMA-r-PgMA)) and Rhodamine B azide are reported, where thermal click reaction between the two components leads to microphase separated morphologies. Both in the bulk and in thin films, increasing the azide loading ratio resulted in the transition from a lamellar microdomain morphology to a hexagonally packed cylindrical mircodomain morphology. However, in thin films the lamellae-cylinder transition was observed at a different azide loading ratio, which was determined by film thickness. As a result, significant deviations from the bulk morphology were observed. These results indicate that surface interactions and confined geometry can play an important role in dictating the morphology in thin films of BCP/additive binary blends.
CONFINED LAMELLA FORMATION IN CRYSTALLINE-CRYSTALLINE POLY(ETHYLENE OXIDE)-b-POLY(-CAPROLACTONE) DIBLOCK COPOLYMERS
Fei-fei Xue , Xue-si Chen , Li-jia An , Sergio S. Funari , Shi-chun Jiang
2013, 31(9): 1260-1270  doi: 10.1007/s10118-013-1325-5
[Abstract](627) [FullText HTML] [PDF 0KB](0)
Abstract:
The real time and in situ investigation of the crystallization process and structure transitions of asymmetric crystalline-crystalline diblock copolymers from the melt was performed with synchrotron simultaneous SAXS/WAXS. The asymmetric poly(ethylene oxide)-b-poly(-caprolactone) diblock copolymers were chosen for the present study. It was shown that the short blocks crystallized later than the long blocks and final lamellar structure was formed in all of the asymmetric diblock copolymers. The final lamellar structure was confirmed by AFM observation. The SAXS data were analyzed with different methods for the early stage of the crystallization. The Guinier plots indicated that there were no isolated domains formed before the formation of lamellae in the asymmetric diblock copolymers during the crystallization process. Debye-Bueche plots implied the formation of correlated domains during crystallization.
PREPARATION OF MDPE-g-MAH COPOLYMERS AND THEIR EFFECT ON PROPERTIES OF MDPE/CaCO3 SYSTEMS
Guo-dong Zhao , Xiao-bo Liu , Guang-nan Qiu , Jian-ming Xu , Shi-ping Xie , Xian-feng Liu , Jian-song Yang , Lan-hang Xu
2013, 31(9): 1271-1275  doi: 10.1007/s10118-013-1334-4
[Abstract](644) [FullText HTML] [PDF 0KB](0)
Abstract:
MDPE-g-MAH copolymers were prepared with MDPE (medium density polyethylene) and MAH (maleic anhydride) under different irradiation doses of high-energy electron accelerator, and FTIR spectra confirmed their structure. The effect of the different contents of MDPE-g-MAH copolymers on properties of MDPE/CaCO3 system is studied intensively. By adding 4 Phr (parts per hundred of resin) MDPE-g-MAH in MDPE/CaCO3 system under irradiation dose of 0.7 MGy, the tensile strength increases from 16.3 MPa to 19.9 MPa, and elongation at break increases from 437% to 518%. SEM images show the domain size of CaCO3 in MDPE-g-MAH systems becomes small. Definitely, MDPE-g-MAH copolymer could improve the compatibility of MDPE/CaCO3 system effectively.
INCREASED SPHERULITIC GROWTH RATES OF SEMICRYSTALLINE POLYMER DUE TO ENHANCED LIMITED LOCAL CHAIN SEGMENTAL MOBILITY AT THE INTERFACE OF DOUBLE-LAYER THIN FILMS
Ya-qiong Zhang , Zhi-gang Wang
2013, 31(9): 1276-1283  doi: 10.1007/s10118-013-1326-4
[Abstract](590) [FullText HTML] [PDF 0KB](0)
Abstract:
In this work the nucleation and growth of spherulites for the below polylactide (PLA) layer in poly(-caprolactone)/polylactide (PCL/PLA) double-layer films during isothermal crystallization at various temperatures above the melting point of PCL have been investigated by using polarized optical microscopy (POM). It is revealed that two types of spherulitic morphologies are observed in PCL/PLA double-layer films. One is the well defined highly birefringent spherulites, and the other one is the coarse spherulites. It is interesting to find that the spherulitic growth rate of the coarse spherulites is higher than that of the well defined spherulites. It is thought that the coarse spherulites nucleate and grow with the assistance of the interfaces between the PCL and PLA layers, and the well defined highly birefringent spherulites only nucleate and grow in the PLA layer.
SYNTHESIS AND CHARACTERIZATION OF WATER-SOLUBLE CdSe NANOPARTICLES CAPPED BY AOT
Yan-ming Chen , Xiao-bo Nie
2013, 31(9): 1284-1289  doi: 10.1007/s10118-013-1329-1
[Abstract](616) [FullText HTML] [PDF 0KB](0)
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Water-soluble CdSe nanoparticles were synthesized using AOT (sodium bis(2-ethylehexyl)-sulfosuccinate) as stabilizer, cadmium acetate and Na2SeSO3 as precursors in aqueous phase. The influence of some key factors, such as reaction time, temperature, concentration and molar ratio of precursors on the optical properties of CdSe nanoparticles was systematically investigated through UV-Vis and PL spectra. Powder X-ray diffraction (XRD) was used to characterize the crystalline structure of synthesized CdSe nanoparticles. As-prepared CdSe nanoparticles exhibit an apparent quantum confinement effect and typical hexagonal wurtzite structures. Finally, the optimal experimental conditions were obtained.
INTERACTION BETWEEN POLY (ETHYLENE OXIDE) AND SILICA NANOPARTICLES IN DILUTE SOLUTIONS
Da-peng Wang , Mu-quan Yang , Zhi-xin Dong , Shu-qin Bo , Xiang-ling Ji
2013, 31(9): 1290-1298  doi: 10.1007/s10118-013-1321-9
[Abstract](607) [FullText HTML] [PDF 0KB](0)
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A mixed system that includes poly(ethylene oxide) (PEO) and silica (SiO2) nanoparticles is prepared using two mixing methods. The interaction between PEO and the SiO2 nanoparticles in the dilute basic solution is investigated using the dynamic light scattering (DLS) and isothermal titration calorimetry (ITC) techniques. The DLS results show qualitatively that SiO2 nanoparticles interact with both random coils and aggregates of PEO through hydrogen bonding, and PEO-SiO2 complexes are formed. The degree of disaggregation of aggregates of PEO is readily adjusted by changing the concentration of SiO2 nanoparticle suspensions. Moreover, the ITC results also certify quantitatively the interaction between PEO and SiO2 nanoparticle, and give the evidence of formation of PEO-SiO2 complex.
EFFECT OF SURFACE CHARGE OF POLYMERIC MICELLES ON IN VITRO CELLULAR UPTAKE
Dan-hua Zhou , Jie Zhang , Guan Zhang , Zhi-hua Gan
2013, 31(9): 1299-1309  doi: 10.1007/s10118-013-1332-6
[Abstract](630) [FullText HTML] [PDF 0KB](0)
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This work focuses on the interaction between polymeric micelles with different charged surfaces and cancer cells in order to study the influence of surface charge on the in vitro cellular uptake efficiency. The amphiphilic diblock copolymers poly(-caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) with different functional groups at the end of hydrophilic block were synthesized. The functional groups endue the micelles with different charges on the surfaces. The cellular uptake of micelles to T-24 cells (human bladder tumor cells), HepG2 cells (human liver hepatocellular carcinoma cell line) and Hela cells (human epithelial cervical cancer cells) was studied by means of flow cytometer and confocal laser scanning microscopy. The results indicate that the surface charges showed great influence on zeta potential of micelles at different pH values. The in vitro cellular uptake efficiency of micelles with different charged surfaces demonstrated different cellular uptake patterns to three kinds of cancer cells.
A REAL-TIME AFM STUDY ON CRYSTAL NUCLEATION AND GROWTH IN NANODROPLETS OF ISOTACTIC POLYPROPYLENE
Jun-chai Zhao , Bo Xing , Zheng Peng , Jian-min Zhang
2013, 31(9): 1310-1320  doi: 10.1007/s10118-013-1330-8
[Abstract](542) [FullText HTML] [PDF 0KB](0)
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Isotactic polypropylene (iPP) nanodroplets were prepared by using the classical droplet method in this study. The formation of nanodroplets allowed the controlled observation of polymer nucleation as well as access to crystal growth at exceptionally high supercooling in iPP. Three cases including the heterogeneous nucleation and fast crystallization in iPP droplets, the formation of multiple independent homogeneous nuclei within a single droplet and a single nucleus within a single droplet were detected by using atomic force microscopy (AFM) during gradually cooling after remelting the nanodroplets. Moreover, it is found that when the volume of droplet is larger than the value of ca. 130000 nm3, the first case was observed. Otherwise, the latter two cases appeared. The temperature at which the onset of nucleation was observed in individual droplets was found to be mainly dependent on height of the droplets when the size scale of the droplet is comparable to the size of the critical nucleus in at least one dimension, which indicates the nucleation behavior under confinement.
IN SITU OBSERVATION OF MELTING AND CRYSTALLIZATION BEHAVIORS OF POLY(-CAPROLACTONE) ULTRA-THIN FILMS BY AFM TECHNIQUE
Cong-de Qiao , Shi-chun Jiang , Xiang-ling Ji , Li-jia An
2013, 31(9): 1321-1328  doi: 10.1007/s10118-013-1333-5
[Abstract](548) [FullText HTML] [PDF 0KB](0)
Abstract:
The melting and crystallization behaviors of poly(-caprolactone) (PCL) ultra-thin films with thickness from 15 nm to 8 nm were studied by AFM technique equipped with a hot-stage in real-time. It was found that melting can erase the spherulitic structure for polymer film with high thickness. However, annealing above the melting point can not completely erase the tree-like structure for the thinner polymer film. Generally, the structure formation of thin polymer films of PCL is controlled not only by melting and crystallization but also by dewetting during thermal annealing procedures, and dewetting predominates in the structure formation of ultra-thin films. However, the presence of tree-like morphology at 75℃ may be due to the strong interaction between PCL and mica surface, which may stick the PCL chains onto the mica surface during thermal annealing process. Moreover, the growth of the dendrites was investigated and it was found that crystallization is followed from a dewetted sample, and the branches did not grow with the stems. The crystallization of polymer in the ultra-thin films is a diffusion-controlled process. Both melting and crystallization behaviors of PCL in thin films are influenced by film thickness.
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