Functional gold nanorod particles on conducting polymer poly(3-octylthiophene) as non-enzymatic glucose sensor

The immobilization of surface-functionalized self-assembled monolayer (SAM) gold nanoparticles onto poly(3-octylthiophene) (POT) was achieved by the cooperation of hydrophobic forces. SAMs were prepared by 11-mercaptoundecanoicacid (MUA), 4-mercaptophenyl boronic acid (MPB), and 1-decanethiol (DT) hydrophobic substrates. Nanoparticles-SAM-POT system was characterized by cyclic voltammetry, SEM, EDAX and contact angle measurements. SAMs (MUA) is closely packed providing effective blocking of the underlying platinum electrode and preventing a ferrocyanide molecule from penetrating. However, potential scanning was applied at SAMs (MUA) modified electrode on which electron penetrating holes or defects were occured. Since SAMs (MPB) is poorly packed according to SAMs (MUA), ferrocyanide molecules could penetrate to SAMs (MPB) modified electrode surface. POT-Au-SAM (MPB) electrode was used for glucose determination as potentiometric non-enzymatic glucose sensor. The analytical performance was evaluated and linear calibration graphs were obtained in the concentration range of 5-30 mM glucose including the level of human blood glucose.     

聚(3-辛基噻吩)的溶致变色、热致变色及发光性能

采用三氯化铁法合成了聚(3 辛基噻吩)(P3OT),利用核磁共振氢谱确定产物中含有摩尔分数为60%的头尾(HT)结构。通过改变良溶剂三氯甲烷与不良溶剂甲醇的体积配比,研究了P3OT的溶致变色行为,P3OT的紫外吸收峰随着甲醇用量的增加发生红移,在φ(CH3OH)=70%时,吸收峰从纯三氯甲烷溶液的435nm红移至490nm。在室温和0℃下,研究了紫外-可见吸收光谱随温度的变化,温度降低,P3OT的吸收峰发生蓝移。以400nm的光激发P3OT的三氯甲烷溶液,在573nm处得到了稳定的发射峰。     

Cocrystallization mechanism of poly(3-alkyl thiophenes) with different alkyl chain length

The crystallization rates of poly(3-alkyl thiophene) (P3AT) cocrystals having different alkyl chain length (e.g. hexyl and octyl) of the components are measured using differential scanning calorimetry (DSC) technique. Two pairs of cocrystals with varying compositions of the components viz. poly(3-octyl thiophene) (P3OT(R), regioregularity 89 mol%) and poly(3-hexyl thiophene) [P3HT(R), regioregularity 92 mol% and P3HT-2 regioregularity 82 mol%] are used. In both the systems the isothermal temperature range (TR) in the same time scale of crystallization is found to decrease with increasing alkyl chain length in the blends. The crystallization rate at the same T_c decreases with increasing alkyl chain length P3AT concentration and the Avrami exponent values of cocrystals are same with those of the component values. The low Avrami exponent values (0.23-1.16) in all the samples suggest the presence of rigid amorphous portion which can not diffuse out quickly from the crystal growth front (soft impingement). Analysis of crystallization rate using Laurintzen-Hoffman (L-H) growth rate theory indicates that there is regime-I to regime-II transition in all the samples. The product of lateral (σ) and end surface energy (σ_e) values are found to decrease with increasing the concentration of longer alkyl chain P3AT in the blend. Analysis of σ values according to a theory of Hoffman et al. [Hoffman JD, Miller RL, Marand H, Rotiman DR. Macromolecules 1992;25:2221. [14]] indicates that there is chain extension of the components in the melt of the blends, however, the entropy of cocrystallization has different sign to the two systems. Cocrystallization in P3HT(R)/P3OT(R) system is an entropy driven process but that in P3HT(2)/P3OT(R) system is entropy forbidden process. A possible explanation of cocrystallization in the later system has been attributed from small interaction between the components.     

Microscopy and microbeam X-ray analyses in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with amorphous poly(vinyl acetate)

Double ring-banded spherulites of biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV with 12 wt% 3HV) blending with 30 wt% amorphous poly(vinyl acetate) (PVAc) were examined using polarized light optical microscopy (POM), scanning electron microscopy (SEM), atomic-force microscopy (AFM) and micro-beam X-ray diffraction. A ring-banded spherulite of PHBV/PVAc 70/30 blend was linearly scanned across the bands in 5 μm steps by means of micro-beam X-ray diffraction. Solvent-etching and fracturing were utilized for probing the interior lamellar textures of the blend samples. Detail interior lamellar orientations in bulk film of PHBV three-dimensional ring-banded spherulites were revealed. SEM and micro-beam X-ray diffraction results suggest that the PHBV lamellar orientation gradually change along the radial growth direction with right-handed rotation sense. The blending effect in band pattern (width and regularity) of PHBV/PVAc blend was discussed.     

Molecular dynamics simulation studies of binary blend miscibility of poly(3-hydroxybutyrate) and poly(ethylene oxide)

By means of full atomistic molecular dynamics simulation, the solubility parameters for pure poly(3-hydroxybutyrate) and poly(ethylene oxide) are calculated and the results are in agreement with the literature values. Furthermore, in order to reveal the blend property, the volume-temperature curve of the PHB/PEO blend system (1:2 blends in terms of repeated units) is simulated by employing the united atom approximation to obtain the glass transition temperature. From the volume-temperature curve, the glass transition temperature is about 258 K, which is compared well with the experimental results. It should be pointed out that the two simulated solubility parameters are similar and there is only one glass transition of the blend system, these indicate that the studied blend system is miscible.     

Solid-state NMR study on the structure and mobility of the noncrystalline region of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

The noncrystalline structures of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymers were studied by variable temperature solid-state wide-line ¹H NMR and solid-state high-resolution ¹³C NMR spectroscopy. It is found that at room temperature there exists a rich and rigid component in the noncrystalline region of PHB and PHBV. The content of this component decreases with the increase in 3-hydroxyvalerate content in PHBV and with the increase in temperature. The brittleness of PHB may be partly attributed to the rigidness of the noncrystalline region at room temperature, while the improvement of the properties of PHBV may come from the enhanced mobility of the noncrystalline region.     

Segregation morphology of poly(3-hydroxybutyrate)/poly(vinyl acetate) and poly(3-hydroxybutyrate-co-10% 3-hydroxyvalerate)/poly(vinyl acetate) blends as studied via small angle X-ray scattering

Segregation morphology of poly(3-hydroxybutyrate) (PHB)/poly(vinyl acetate) (PVAc) and poly(3-hydroxybutyrate-co-10% 3-hydroxyvalerate) (P(HB-co-10% HV)/PVAc blends crystallized at 70 °C have been investigated by means of small angle X-ray scattering (SAXS). Morphological parameters including the crystal thickness (l_c) and the amorphous layer thickness (l_a) were deduced from the one-dimensional correlation function (γ(z)). Blending with PVAc thickened the PHB crystals but not the P(HB-co-10% HV) crystals. On the basis of the composition variation of l_a, and the volume fraction of lamellar stacks (?_s) revealed that PHB/PVAc blends created the interlamellar segregation morphology when the weight fraction of PVAc (w_PVAc)≤0.2 and the interlamellar and interfibrillar segregation coexisted when w_PVAc>0.2, while P(HB-co-10% HV)/PVAc blends yielded the interfibrillar segregation morphology at all blend compositions. For both PHB/PVAc and P(HB-co-10% HV)/PVAc blends, the distance of PVAc segregation was promoted by increasing PVAc composition and the distance of PVAc segregation in P(HB-co-10% HV)/PVAc blends was greater than in PHB/PVAc at a given PVAc composition. The crystal growth rate played a key role in controlling the segregation of PVAc.     

Thermal undoping behavior of FeCl3-doped poly(3-octylthiophene)

For neutral and FeCl₃-doped poly(3-octylthiophene) (P3OT), measurements of ⁵⁷Fe Mössbauer spectroscopy, conductivity, thermogravimetric analysis, differential scanning calorimetry and dynamic mechanical analysis are performed in order to understand the thermal undoping behavior. It is found that the counter anion for the doped P3OT is FeCl₄. At the doping level 0.33, its glass transition temperature (T_g) shifts from 11.2 °C at the neutral state to 137 °C. During the heat treatment, the aggregation of the dopant occurs between 65 to 150 °C (centered at 99 °C) and the decomposition of dopant anions occurs between 150 to 236 °C (centered at 188 °C). The aggregation of the dopant anion in the glass transition period is resulted from the increased ring distortion in the subchains, which leads to a slow decrease in conductivity. As the dopant anions decomposes, the conductivity drops sharply.     

Thermal properties of poly(styrene-block-ε-caprolactone) in blends with poly(vinyl methyl ether)

The thermal characteristics of a styrene-ε-caprolactone diblock copolymer, P(S-b-CL), in blends with poly(vinyl methyl ether) (PVME) were studied by DSC. The glass transition temperatures show that PVME is only dissolved in the PCL block. It segregates from the PCL block at low temperatures. The addition of PVME leads to increasing crystallinity of the PCL block in a certain range of composition. However, degrees of crystallinity do not change significantly with crystallization temperature. Optical inspection revealed that the PCL block does not form spherulites. The crystallization kinetics of the PCL block has been systematically studied. The rate constants of crystallization for different blends decrease exponentially with crystallization temperature, whereas the rates of crystallization are scarcely affected by PVME content. The Avrami exponents were found close to two.     

The domain structure and mobility of semi-crystalline poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate): A solid-state NMR study

Solid-state NMR techniques have been employed to investigate the domain structure and mobility of the bacterial biopolymeric metabolites such as poly(3-hydroxybutyrate) (PHB) and its copolymers poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) containing 2.7 mol% (PHBV2.7) and 6.5 mol% (PHBV6.5) 3-hydroxyvalerate. Both single-pulse excitation with magic-angle spinning (SPEMAS) and cross-polarization magic-angle spinning (CPMAS) ¹³C NMR results showed that these biopolymers were composed of amorphous and crystalline regions having distinct molecular dynamics. Under magic-angle spinning, ¹H T_1ρ and ¹³C T₁ showed two processes for each carbon. Proton relaxation-induced spectral editing (PRISE) techniques allowed the neat separation of the ¹³C resonances in the crystalline regions from those in the amorphous ones. The proton spin-lattice relaxation time in the tilted rotating frame, , measured using the Lee-Goldburg sequence with frequency modulation (LGFM) as the spin-locking scheme, was also double exponential and significantly longer than ¹H T_1ρ. The difference between for the amorphous and crystalline domains was greater than that of ¹H T_1ρ. Our results showed that the differences could be exploited in LGFM-CPMAS experiments to separate the signals from two distinct regions. ¹H spin-diffusion results showed that the domain size of the mobile components in PHB, PHBV2.7 and PHBV6.5 were about 13, 24 and 36 nm whereas the ordered domain sizes were smaller than 76, 65 and 55 nm, respectively. The results indicated that the introduction of 3-hydroxyvalerate into PHB led to marked molecular mobility enhancement in the biopolymers.     

Synthesis, fabrication and characterization of poly[3-3′(vinylcarbazole)] (PVK) Langmuir-Schaefer films

Poly[3-3′(vinylcarbazole)] (PVK) was synthetized with N-vinylcarbazole as monomer by oxidative polymerization with ferric chloride. The resulting polymer was then deposited on various solid supports by using Langmuir-Schaefer (LS) method. The pressure-area isotherm of PVK revealed the possibility of compact monolayer formation at air-water interface. Different layers of PVK were doped with iodine vapours. Both scanning probe microscopy and optical microscopy images indicated a good uniformity of the films. The morphology and the thickness of PVK films were investigated using atomic force microscopy. The voltammetric investigation of I₂ doped PVK showed a distinctive electrochemical behaviour. The photoinduced charge transfer across a donor/acceptor (D/A) hybrid interface provided an effective method to study the photoelectrochemical properties of the composite LS films.     

Synthesis and characterization of copolymers of poly(m-xylylene adipamide) and poly(ethylene terephthalate) oligomers by melt copolycondensation

Poly(m-xylylene adipamide)/poly(ethylene terephthalate)(MXD6/PET) copolymers are synthesized by melt copolycondensation with 1–5 wt% low molecular weight PET oligomers into the MXD6 oligomers at 260 °C.FR-IR and1 H NMR analysis results indicate that the interchange reaction has occurred between MXD6 oligomers and PET oligomers. The thermal behavior of copolymers shows that the melting temperature of MXD6/PET copolymers decreases with the increasing of amount of PET oligomers, while the crystallization temperature accordingly increases. And the equilibrium temperature Tm0 is evaluated to be 251.8 °C for the copolymers with5 wt% PET oligomer adding, which is very close to that of neat MXD6. The tensile and impact strength of MXD6/PET copolymers are significantly improved than that of pure MXD6 by mechanical properties test, and the microfibril structure in the impact fracture sample's surface reveals the feature of ductile fracture.     

Electrochemical behavior of poly(3-hexylthiophene). Controlling factors of electric current in electrochemical oxidation of poly(3-hexylthiophene)s in a solution

Electrochemical response of regio-random and regio-controlled poly(3-hexylthiophene), P3HexTh, was investigated by cyclic voltammetry. P3HexTh underwent electrochemical oxidation at about 0.4 V vs. Ag⁺/Ag in a THF solution, and the peak anode electric current, i_pa, was proportional to the sweeping rate v; i_pa=const×v^1/2. These data indicated that diffusion of the P3HexTh molecule in the solution was important to determine i_pa. Application of a Matsuda's equation with assumptions gave a diffusion coefficient, D, of about 1×10⁻⁷ cm² s⁻¹ at molecular weight of about 5000, and the D value steeply decreased with increase in the molecular weight.     

Poly(N-vinylpyrrolidone)-grafted poly(N-isopropylacrylamide) copolymers: Synthesis, characterization and rapid deswelling and reswelling behavior of hydrogels

Poly(N-isopropylacrylamide)-block-poly(N-vinylpyrrolidone) diblock copolymer (PNIPAAm-b-PVPy) was successfully synthesized via sequential reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process, in which the chain transfer agent of xanthate was in situ afforded via the reaction of isopropylxanthic disulfide (DIP) with 2,2-azobisisobutylnitrile (AIBN). The RAFT/MADIX technique was employed to prepare the poly(N-vinylpyrrolidone)-grafted poly(N-isopropylacrylamide) copolymers (PNIPAAm-g-PVPy) with N,N-methylenebisacrylamide as the crosslinking agent. The comb-like PNIPAAm-g-PVPy copolymer networks with PVPy as the pendent chains were characterized by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS). The hydrogel behavior of PNIPAAm-g-PVPy networks was investigated in terms of swelling, deswelling and reswelling tests. With the inclusion of PVPy chains, the swelling ratios of the hydrogels were significantly enhanced compared to the control PNIPAAm hydrogel. It is found that the PVPy-modified PNIPAAm hydrogels displayed faster response to the external temperature changes than the control PNIPAAm hydrogel. The improved thermoresponsive properties of hydrogels are ascribed to the formation of the comb-like architectures in the copolymer networks.     

Synthesis and thermal characterization of poly(butylene terephthalate-co-thiodiethylene terephthalate) copolyesters

Poly(butylene terephthalate-co-thiodiethylene terephthalate) copolymers of various compositions were synthesized and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by thermogravimetric analysis and differential scanning calorimetry. All the polymers under investigation show a good thermal stability. At room temperature they appear as semicrystalline materials: the main effect of copolymerization was a lowering in the amount of crystallinity and a decrease of melting temperature with respect to homopolymers. A pure crystalline phase has been evidenced at high content of butylene terephthalate or thiodiethylene terephthalate units and Baur's equation was found to describe well the T_m-composition data. Amorphous samples (containing 50-100 mol% of thiodiethylene terephthalate units) showed a monotonic decrease of T_g as the content of sulfur-containing units is increased, due to the presence of flexible C-S-C bonds in the polymeric chain. Finally, the Fox equation described well the T_g-composition data.     

Morphological and electrochemical characterization of a poly(3-methylthiophene)/PVDF composite

Composite electrodes were prepared via electrochemical polymerization of 3-methylthiophene in porous PVDF membranes of various thicknesses. The electrochemical properties were determined by cyclic voltammetry and charge-discharge tests and the possible correlation of the results with the morphology of the host membranes was examined. The best definition of n- and p-doping/undoping processes and the biggest capacitance (82 F g⁻¹) were obtained with a 27.5 μm-thick composite. Further characterization of this composite using electrochemical impedance spectroscopy revealed three behaviors associated with variation in the oxidation state of poly(3-methylthiophene) during transition from the n-undoping to p-doping states. The behavior of the charge transfer resistance and the double layer capacitance as a function of the applied potential were also determined.     

Polymer micelle-like aggregates of novel amphiphilic biodegradable poly(asparagine) grafted with poly(caprolactone)

Novel amphiphilic graft copolymers composed of poly(asparagine) (PAsn) as the hydrophilic backbone and poly(caprolactone) (PCL) as the hydrophobic segment were successfully synthesized by grafting PCL-HMDs to poly(succinimde). After tosylating PCL-diol with p-toluenesulfonylchloride (TsCl), tosylated poly(caprolactone) (PCL-OTs) was then reacted with hexamethylenediamine (HMD). The reaction of the amine terminated PCL with poly(succinimide) (PSI) and the following aminolysis resulted in poly(aspargine)-graft-poly(caprolactone) (PAsn-g-PCL). The degree of substitution (DS) and grafting reaction was confirmed by ¹³C NMR, FT-IR spectroscopy and elemental analysis. X-ray diffraction and DSC thermogram showed that the crystalline domain originated from PCL became apparent with an increase of DS. The amphiphilic comb-type graft polymer formed self-aggregates in aqueous solution when precipitated and dialysed against distilled water. Strong hydrophobic interaction of associated PCL grafts facilitated primary aggregate formation with DS, significantly reducing critical aggregation concentration and secondary aggregates also appeared in DLS measurements. Self-aggregates showed a bimodal size distribution originated from the self-aggregation and kinetically controlled particle aggregation, although the smaller primary aggregates was predominant. Spherical and dispersed aggregates of about 20 nm in diameter were observed by a transmission electron microscope.     

Synthesis and characterization of adamantane-containing poly(enaminonitriles)

The first aliphatic bis(chlorovinylidene cyanide) monomer, 1,3-bis(1-chloro-2,2-dicyanovinyl)adamantane, has been synthesized and polymerized with appropriate diamines to give adamantane-containing aromatic-aliphatic and all aliphatic poly(enaminonitriles) (PEANs) via vinylic nucleophilic substitution polymerization. The PEANs showed excellent solubility in polar aprotic solvents and good thermal stability (10% weight loss in air > 320 °C), despite the aliphatic contents of the polymers. Solution inherent viscosities of 0.23-0.90 dL/g were obtained.Three other new PEANs containing the adamantane-based cardo group were also synthesized via vinylic nucleophilic substitution polymerization from the adamanaine-containing cardo diamine 2,2-bis[4-(4-aminophenoxy)phenyl]adamantane. The cardo PEANs showed better solubility in common organic solvents than the corresponding cardo polyamides. They also showed good thermal stabilities (10% weight loss in air > 339 °C) comparable to those of the corresponding cardo polyamides.     

Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate)

Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a ¹H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes and their particle sizes were less than 100 nm. In a ¹H-NMR study in D₂O, specific peaks of PEG solely appeared while peaks of PHO disappeared, indicating that nanoparticles have core-shell structures. The higher M.W. of PEG decreased loading efficiency and particle size. The higher drug feeding increased drug contents and average size of nanoparticles. In the drug release study, the higher M.W. of PEG block induced the acceleration of drug release rate. The increase in drug contents induced the slow release rate of drug. In an antitumor activity study in vitro, paclitaxel nanoparticles have practically similar anti-proliferation activity against HCT116 human colon carcinoma cells. In an in vivo animal study using HCT116 colon carcinoma cell-bearing mice, paclitaxel nanoparticles have enhanced antitumor activity compared to paclitaxel itself. Therefore, paclitaxel-incorporated nanoparticles of PHO/PEG block copolymer are a promising vehicle for antitumor drug delivery.     

Synthesis, characterization, and properties of poly(ethylene terephthalate)/poly(1,4-butylene succinate) block copolymers

Reactive blending at 290 °C of a series of mixtures of poly(ethylene terephthalate) (PET) and poly(1,4-butylene succinate) (PBS) led to the formation of block PET/PBS copolyesters. The block lengths of the resulting copolymers decreased with the severity of the treatment. Copolyesters with PET/PBS molar compositions of 90/10, 80/20, 70/30, and 50/50 were prepared by this method and their composition and microstructure were characterized by ¹H and ¹³C NMR, respectively. The T_g, T_m, and crystallinity of the copolymers decreased as the content in PBS and the degree of randomness increased. The elastic modulus and tensile strength of the copolymers decreased with the content of PBS, whereas, on the contrary, the elongation at break increased. The PET/PBS copolymers exhibited a pronounced hydrolytic degradability, which increased with the content in 1,4-butylene succinic units. Hydrolysis mainly occurred on the aliphatic ester groups.