Preparation and research of PCL/cellulose composites: Cellulose derived from agricultural wastes.

For the rational use of agricultural wastes, bagasse, orange peel and wheat bran were used to fabricate bio-based polymer materials. Cellulose was extracted from the three different agricultural wastes, and poly(ε-caprolactone) (PCL) was used as the matrix material. PCL was mixed with nanocrystalline cellulose (CNC), extracted bagasse cellulose (GC), orange peel cellulose (JC) and wheat bran cellulose (MC) by solution casting. Morphology and structure of the extracted cellulose were studied by Scanning Electron Microscope, Fourier Infrared spectrometer, thermogravimetry and X-ray diffractometer. The influence of GC, JC, MC on the crystallization process and mechanical properties of PCL was investigated by DSC and tensile test. Experimental results show that the addition of CNC, GC, JC, MC increases the crystallization temperature of PCL, accelerates the crystallization process of PCL, and improves the tensile property of PCL.

Effect of ionic crosslinking on morphology and thermostability of biomimetic supercritical fluids-decellularized dermal-based composite bioscaffolds for bioprinting applications.

In the present study, supercritical fluid was employed to prepare a kind of supercritical fluids-decellularized dermal-based scaffold (SFDDS) from porcine dermal tissue. Further, new composite bioscaffolds containing SFDDS were designed for bioprinting applications. Then, the effect of crosslinking functionality on microstructures and thermal properties of the composite bioscaffolds containing decellularized extracellular matrix were studied. The results of thermal stability from thermogravimetric analysis and difference thermogravimetry demonstrated the structural stability of the composite bioscaffolds. A method was designed to prepare bioinspired decellularized dermal-based composite bioscaffolds, which were further characterized by infrared spectroscopy, scanning electron microscopy, and thermogravimetry analysis.

Azobenzene Based Photo-Responsive Hydrogel: Synthesis, Self-Assembly, and Antimicrobial Activity.

A new azobenzene-based symmetric amphiphile was synthesized and characterized using 1H NMR spectroscopy. Its self-assembly behavior as well as photo-responsive behavior in its solution and gel states were investigated. Such a compound can self-assemble into fiber mesophases in water solvent. After irradiation of the gels with UV light, the trans isomer of the compound rapidly photoisomerized to the cis isomer, which resulted in a rapid destruction of the gel. High temperature also caused a rapid drop in viscosity. To verify the antimicrobial activity of the hydrogel, live and death assays of human fibroblasts L929 properties were used for in vitro cell viability studies. The compound was converted to the terminal tertiary amine in a quaternary ammonium salt molecule by using hydrochloric acid. This azobenzene quaternary ammonium salt has a relatively better antimicrobial effect biocidal activity that was demonstrated when challenged against Escherichia coli on in vitro conditions.

Biochar Nanocomposite Derived from Watermelon Peels for Electrocatalytic Hydrogen Production.

Water splitting is the most potential method to produce hydrogen energy, however, the conventional electrocatalysts encounter the hindrances of high overpotential and low hydrogen production efficiency. Herein, we report a carbon-based nanocomposite (denoted as CCW-x, x stands for the calcination temperature) derived from watermelon peels and CoCl2, and the as-synthesized CCW-x is used as the electrocatalyst. The overpotential and the Tafel slope of CCW-700 for oxygen evolution reaction (OER) is 237 mV at 10 mA cm-2 and 69.8 mV dec-1, respectively, both of which are lower than those of commercial RuO2. For hydrogen evolution reaction (HER), the overpotential of CCW-700 (111 mV) is higher than that of the widely studied Pt/C (73 mV) but still lower than those of lots of carbon-based nanomaterials (122-177 mV). In the light of CCW-700 is highly active for both OER and HER, we assembled a water-splitting electrocatalyst by employing nickel foam loaded with CCW-700 as the anode and cathode in 1 M KOH. The water-splitting voltage is only 1.54 V for the CCW-700//CCW-700 electrodes and 1.62 V for the RuO2//Pt/C ones. Therefore, the so-denoted CCW-x powder possesses good electrocatalytic hydrogen production efficiency.

Functionalized cellulose nanocrystals as the performance regulators of poly(ß-hydroxybutyrate-co-valerate) biocomposites.

To investigate the relationship between functional groups on cellulose nanocrystals (CNC) and the performance of poly(ß-hydroxybutyrate-co-valerate) (PHBV), the surface of CNC was modified by surface graft modification and PHBV/CNC biocomposites were prepared by melt blending. To demonstrate the interfacial adhesion difference between hydrophobic PHBV and hydrophilic CNC, palmitoyl chloride and ε-caprolactone had been used to tailor the oleophilic property of CNC. Results showed that CNC had heterogeneous nucleation effect on the crystallization process of PHBV, while the entanglement of molecular chains weakened the promoting functions of CNC-g-C16 (CNC grafted with palmitoyl chloride) and CNC-g-CL (CNC grafted with ε-caprolactone). Furthermore, CNC-g-CL exhibited better interfacial adhesion with PHBV when compared with CNC-g-C16. And 1 wt% CNC-g-CL improved the tensile strength of PHBV biocomposite to 38.09 MPa, which is 26.25% higher than PHBV.

Multistimuli responsive organogels based on a reactive azobenzene gelator.

A reactive azobenzene based super organogelator was found to rapidly and reversibly transform a range of hydrophobic solvents from gels to solutions upon changes in temperature, light and shear force. More specifically they formed gels at concentrations as low as 0.08 wt%. Upon heating, exposure to UV light, or application of shear, the π-π bonding was disrupted which resulted in a rapid drop of both modulus and viscosity. This was confirmed by (1)H NMR, SAXS, and rheological measurements. Although many examples of organogelators are known in the literature, this is the first time that a reactive group, a benzoyl chloride, has been incorporated in a supramolecular organogel structure. Moreover, this group is available for subsequent synthetic modifications. The presence of benzoyl chloride groups showed a remarkable effect on the formation and properties of the gels. Compared with other approaches, this strategy is advantageous in terms of structural design since it not only produces a multi-responsive soft material but also allows facile modifications which may expand the applications of organogels to other fields.

Polymer mixtures with enhanced compatibility and extremely low viscosity used as DNA separation media.

Poor compatibility was the major drawback of polymer mixtures when used as DNA separation media. Using poly(ethylene oxide)-b-poly(N, N-dimethylacrylamide) (PEO(44)-b-PDMA(88)) and PEO (M(w): 1.3 MDa) as an example, we demonstrated the concept that the compatibility was significantly improved when mixing a homopolymer with its copolymer. Laser light scattering indicated that the major interaction between PEO and PEO-b-PDMA in dilute solution was the weak hydrodynamic interaction, which showed almost no effect on the viscosity and the static scattering pattern. In semidilute or concentrated solution, viscosity measurement also suggested good compatibility between the two components. When tested as DNA separation medium by CE, the viscosity of the mixture was extremely low, only 5 cP for 5.0 m/v% PEO-b-PDMA+0.1 m/v% PEO at 25 degrees C. The performance on DNA separation could be tuned by varying the concentration of each component as well as the component ratio. Good separation on both dsDNA and ssDNA was achieved.

Functionalized gold nanoparticles as additive to form polymer/metal composite matrix for improved DNA sequencing by capillary electrophoresis.

A new matrix additive, poly (N,N-dimethylacrylamide)-functionalized gold nanoparticle (GNP-PDMA), was prepared by "grafting-to" approach, and then incorporated into quasi-interpenetrating network (quasi-IPN) composed of linear polyacrylamide (LPA, 3.3 MDa) and PDMA to form novel polymer/metal composite sieving matrix (quasi-IPN/GNP-PDMA) for DNA sequencing by capillary electrophoresis. Without complete optimization, quasi-IPN/GNP-PDMA yielded a readlength of 801 bases at 98% accuracy in about 64 min by using the ABI 310 Genetic Analyzer at 50 degrees C and 150 V/cm. Compared with previous quasi-IPN/GNPs, quasi-IPN/GNP-PDMA can further improve DNA sequencing performances. This is because the presence of GNP-PDMA can improve the compatibility of GNPs with the whole sequencing system, enhance the entanglement degree of networks, and increase the GNP concentration in system, which consequently lead to higher restriction and stability, higher apparent molecular weight (MW), and smaller pore size of the total sieving networks. Furthermore, the composite matrix was also compared with quasi-IPN containing higher-MW LPA and commercial POP-6. The results indicate that the composite matrix is a promising one for DNA sequencing to achieve full automation due to the separation provided with high resolution, speediness, excellent reproducibility, and easy loading in the presence of GNP-PDMA.

Hydroxyethylcellulose-graft-poly (4-vinylpyridine) as a novel, adsorbed coating for protein separation by CE.

A novel graft copolymer, hydroxyethylcellulose-graft-poly (4-vinylpyridine), used as a physically adsorbed coating of the fused-silica (FS) capillaries, was synthesized by using ceric ammonium nitrate initiator in aqueous nitric acid solution. EOF measurements showed that the above graft copolymer coating of the FS capillaries could suppress EOF effectively compared with the bare FS capillaries. The adsorbed coating exhibited minimal interactions with proteins, providing efficient protein separations with excellent repeatability. Interestingly, the electrical charge of the coated capillary wall could be modulated by varying the pH of the running buffer, which makes possible the analysis of basic and acidic proteins in the same capillary. The effects of pH on suppressing EOF and protein separation were investigated in detail. The results demonstrated that the hydroxyethylcellulose-graft-poly (4-vinylpyridine) copolymer coatings have great potential in the diagnosis and proteomics.

Novel quasi-interpenetrating network/functionalized multi-walled carbon nanotubes double-network composite matrices for DNA sequencing by CE.

Poly(N, N-dimethylacrylamide) (PDMA)-functionalized multi-walled carbon nanotubes (MWNT-PDMA) were prepared via atom transfer radical polymerization and then added into quasi-interpenetrating network (quasi-IPN) composed of linear polyacrylamide (3.3 MDa) and PDMA to form polymer/nanotube double-network composite sieving matrices for DNA sequencing by CE. The CE results show that, compared with quasi-IPN, the novel composite matrices can improve ssDNA sequencing performances due to the formation of a double-network consisting of a flexible quasi-IPN polymer network and a rigid MWNT network based on a unique tubular structure, which makes the total sieving networks more restricted and stable and increases the apparent molecular weight of the matrices. The effects of MWNT-PDMA concentration in matrices and molecular weight of PDMA side chains in MWNT-PDMA on ssDNA sequencing performances were studied in detail. Furthermore, these double-network composite matrices were also compared with other matrices and the results indicate that they are promising ones for DNA sequencing. The separation provided with high resolution, speediness, excellent reproducibility and easy loading owing to the addition of MWNT-PDMA is likely to achieve full automation, especially for capillary array electrophoresis and microchip electrophoresis.

Hydroxyethylcellulose-graft-poly (N,N-dimethylacrylamide) copolymer as a multifunctional separation medium for CE.

A new multifunctional separation medium, hydroxyethylcellulose-graft-poly (N,N-dimethylacrylamide) copolymer synthesized in our laboratory for application in both basic protein separation and dsDNA separation by CE, is presented in this paper. As a noncovalent coating, this medium showed a powerful capability in resisting basic protein adsorption. Highly efficient and rapid protein separation had been obtained at four different pH values. Meanwhile, the 11 fragments of the dsDNA sample could be baseline separated using this grafted copolymer as sieving matrix at an appropriate concentration.

A well-defined diblock copolymer of poly-(ethylene oxide)-block-poly (4-vinylpyridine) for separation of basic proteins by capillary zone electrophoresis.

A series of well-defined diblock copolymers, poly(ethylene oxide)-block-poly(4-vinylpyridine) (PEO-b-P4VP) used as physical coating of capillaries, were synthesized by atom transfer radical polymerization (ATRP). EOF measurement results showed that all synthesized PEO-b-P4VP diblock copolymer-coated capillaries in this report could suppress EOF effectively compared to the bare fused-silica capillaries, and efficient separations of basic proteins were achieved. The effects of the molecular weight of P4VP block in PEO-b-P4VP and buffer pH on the separation of basic proteins for CE were investigated in detail. Moreover, the relationships between morphologies of PEO-b-P4VP diblock copolymers in buffer, which were studied by transmission electron microscopy, and the separation efficiencies of basic protein with PEO-b-P4VP diblock copolymers coatings were discussed.

Cationized hydroxyethylcellulose as a novel, adsorbed coating for basic protein separation by capillary electrophoresis.

We present cationized hydroxyethylcellulose (cat-HEC) synthesized in our laboratory as a novel physically adsorbed coating for CE. This capillary coating is simple and easy to obtain as it only requires flushing the capillary with polymer aqueous solution. A comparative study with and without polymers was performed. The adsorbed cat-HEC coating exhibited minimal interactions with basic proteins, providing efficient basic protein separations with excellent reproducibility. Under broad pHs, the amine groups are the main charged groups bringing about a global positive charge on the capillary wall. As a consequence, the cat-HEC coating produced an anodal EOF performance. A comparative study on the use of hydroxyethylcellulose (HEC) and cat-HEC as physically adsorbed coatings for CE are also presented. The separation efficiency and analysis reproducibility proved that the cat-HEC polymer was efficient in suppressing the adsorption of basic proteins onto the silica capillary wall. The long-term stability of the cat-HEC coating in consecutive protein separation runs has demonstrated the suitability of the coating for high-throughput electrophoretic protein separations.

Effects of novel quasi-interpenetrating network/gold nanoparticles composite matrices on DNA sequencing performances by CE.

Gold nanoparticles (GNPs) with particle sizes of about 20, 40, and 60 nm were prepared and added into a quasi-interpenetrating network (quasi-IPN) composed of linear polyacrylamide (LPA) with different viscosity-average molecular masses of 1.5, 3.3, and 6.5 MDa and poly-N,N-dimethylacrylamide (PDMA) to form polymer/metal composite matrices, respectively. These novel matrices could improve ssDNA sequencing performances due to interactions between GNPs and polymer chains and the formation of physical cross-linking points as demonstrated by intrinsic viscosities and glass transition temperatures. The effects of the parameters in relation to quasi-IPN/GNPs matrices, such as GNP contents, GNP particle sizes, LPA molecular masses, and solution concentrations, on ssDNA sequencing performances were studied. In the presence of GNPs, the separation had the advantages of high resolution, speediness, excellent reproducibility, long shelf life and easy automation. Therefore, less viscous matrix solutions (with moderate size GNPs) due to lower solution concentration and lower-molecular-mass LPA could be used to replace more viscous solutions (without GNPs) due to higher solution concentration or higher-molecular-mass LPA to separate DNA, while the sieving performances were approximate even higher, which helped to achieve full automation especial for capillary array electrophoresis (CAE) and microchip electrophoresis (MCE).

Novel hydroxyethylcellulose-graft-poly acrylamide copolymer for separation of double-stranded DNA fragments by CE.

A novel separation medium, hydroxyethylcellulose-graft-polyacrylamide (HEC-g-PAM) synthesized by atom transfer radical polymerization (ATRP), used for dsDNA separation by CE is presented. The separation performance of HEC-g-PAM, which has the same graft density and different graft length, has been investigated in Tris-boric acid-EDTA (TBE) buffer solvent mixtures. The temperature-dependent rheological behavior of HEC-g-PAM was also studied by steady-shear rheometry. The results showed that dsDNA fragments between 72 and 1353 bp was achieved with a 30 cm effective capillary length at 150 V/cm using this type of graft copolymer as a separation medium in bare fused-silica capillaries, and separation improvement is obtained in HEC-g-PAM compared with HEC and poly(dimethylacrylamide (PDMA).

Novel quasi-interpenetrating network/gold nanoparticles composite matrices for DNA sequencing by CE.

In order to further improve ssDNA sequencing performances using quasi-interpenetrating network (quasi-IPN) as a matrix composed of linear polyacrylamide (LPA) with lower viscosity-average molecular mass (3.3 MDa) and poly(N,N-dimethylacrylamide) (PDMA), gold nanoparticles (GNPs) were prepared and added into this quasi-IPN to form polymer/metal composite sieving matrices. The studies of intrinsic viscosity and differential scanning calorimetry (DSC) on quasi-IPN and quasi-IPN/GNPs indicate that there were interactions between GNPs and polymer chains. The sequencing performances on ssDNA using quasi-IPN and quasi-IPN/GNPs (with different GNPs concentrations) as sieving matrices were studied and compared by CE at different temperatures. The results show that resolutions of quasi-IPN/GNPs were higher than those of quasi-IPN without GNPs and approximated those of quasi-IPN composed of LPA with higher MW (6.5 MDa) and PDMA without GNPs in the bare fused-silica capillaries. Furthermore, the sequencing time of quasi-IPN/GNPs was shorter than that of quasi-IPN under the same sequencing conditions. The influences of GNPs and sequencing temperature on the sequencing performances of ssDNA were also discussed. The separation reproducibility of quasi-IPN/GNPs solution was excellent and its shelf life was more than 8 months.