Comparison of the Physical Properties and in vivo Bioactivities of Flatwise-Spun Silk Mats and Cocoon-Derived Silk Mats for Guided Bone Regeneration Abstract The main flaw of silkworm cocoon originated membranes for guided bone regeneration (GBR) techniques is that the maximum size of the membrane is determined by the size of the cocoon. Flatwise-spun silk does not have any limitation to its production size. The objective of this study was to compare flatwise-spun silk mats with cocoon-derived silk mats for a GBR technique. Tensile strength, scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy and sericin contents analysis were done for in vitro test. Bone regeneration ability was tested in the critical sized defect of the animal model. In this study, flatwise-spun silk mats showed lower tensile strength and similar tensile strain to a cocoon-derived commercialized silk mat (TDI). Compared to TDIs, the flatwise-spun silk mats showed a similar second derivative spectrum, but they showed an increased abundance of the random coil and helix structures in the FT-IR spectra because of a higher content of sericin. In animal model experiments, the bone volume (BV) after the application of a flatwise-spun silk mat was similar to the volume observed after the application of a TDI. Both groups showed a significantly higher BV compared to an unfilled control group (P<0.05). Considering that there was no size limitation in producing flatwise-spun silk mats, their clinical indications could be much wider than cocoon-derived silk mats.

pH-induced Crosslinking of Rice Starch via Schiff Base Formation Abstract Rice starch is an abundant, inexpensive, and biocompatible biopolymer with a wide range of potential applications, particularly in the biomedical field. However, the use of rice starch is limited because of its water-solubility. One way of addressing this is to modify the crosslinking properties. If the degree of crosslinking is sufficiently high, the starch becomes insoluble in water, but it remains swellable. In this study, the first synthesis of pH-induced crosslinking of rice starch without the use of any external chemical crosslinking agent was demonstrated. The crosslinked rice starch was prepared by forming a Schiff base reaction (imine) between the two modified starches: oxidized rice starch (ORS) and amino rice starch (ARS). Here, the ORS and ARS were successfully synthesized, with the content of the glucose units being 32.01 and 27.80 mol%, respectively. Imine bonds were shown to be formed from the aldehyde and amine groups. The relationships between the pH and the degree of crosslinking were also investigated. The chemical structures of the synthesized ORS and ARS and their crosslinked products at different pH levels were determined by 1H NMR, 13C NMR, and FTIR Furthermore, the effect of pH on swelling behavior was explored. The relationships between the pH and the chemical structure agreed well with the swelling behavior. The swelling ratio was the highest at pH 5 and decreased with increased pH. Under basic conditions, hydrolysis was initiated, reducing the crosslink density and the efficiency of water uptake. The present study suggests that the pH-induced crosslinked rice starch can be a promising biomaterial for controlled release applications.

Curcumin Encapsulated Micellar Nanoplatform for Blue Light Emitting Diode Induced Apoptosis as a New Class of Cancer Therapy Abstract Blue light emitting diode (BLED) were known to inhibit cancer proliferation and induced apoptotic cell death by increasing intracellular reactive oxygen species (ROS) and caspase activation. However, not many attempts were made to study the naturally occurring photosensitizer molecule (PS) curcuminoids (CUR) mediated blue light emitting diode induced photodynamic therapy (BLED-PDT). Here, we demonstrated the use of pluronic F127 nanoplatform as a novel BLED-PDT based system for anticancer therapy. Aqueous soluble F127-CUR was proven to significantly mediate BLED-PDT, we anticipate that F127-CUR combined with BLED to induce BLED-PDT could be a promising cancer treatment modality.

Enhancing Microalgal Biomass Productivity in Floating Photobioreactors with Semi-Permeable Membranes Grafted with 4-Hydroxyphenethyl Bromide Abstract Microalgal biomass productivity of semi-permeable membrane photobioreactors (SPM-PBRs) highly depends on diffusion of nutrient ions from surrounding environment through SPMs. The objective of this study was to enhance microalgal biomass productivity in floating photobioreactors (PBRs) with semi-permeable membranes (SPMs) grafted with 4-hydroxyphenethyl bromide (4-HPB) by increasing ion permeabilities and reducing biofouling of SPMs. In this study, we investigated the reduction of biofouling and improvement of biomass productivity by grafting 4-HPB onto SPMs which could decrease hydrophobicity. The degree of alkylation could be increased by up to 4.9%, with water contact angles on alkylated SPM surfaces decreased from 102.5° to 58.2°, indicating decreased surface hydrophobicity. Ion and water permeabilities of SPMs were increased in alkylated SPMs by 148% and 200%, respectively, compared to non-treated SPM control. Moreover, biomass productivity of PBRs with alkylated SPMs was 75% (740 mg m−2 day−1) higher than that of the control. Biofouling was also remarkably reduced by up to 40% in 4-HPB grafted SPMs after cultivation of microalgae. These results suggest that decreasing hydrophobicity of SPMs by grafting 4-HPB could enhance biomass productivity in SPM-PBRs through improving ion permeability and reducing biofouling.

Sulfonated Cross-Linked Poly(ether ether ketone) Films with Wrinkled Structures: Preparation and Vanadium Ions Permeability Abstract Wrinkling patterns were fabricated by sulfonation of ion irradiated poly(ether ether ketone) (PEEK). A variety of wrinkling patterns in the micrometer to sub-micrometer range were observed and were controlled by the adsorbed dose and dose rate of the irradiated ions as well as the sulfonation time. Because of the properties of these micro-textured membranes, they are promising for a broad range of applications. In particular, the cross-linked membranes had a very low permeability of vanadium ions, i.e. 1.5 × 10−7 cm2 min−1 due to their wrinkled structures in combination with the Donnan exclusive effect.

Reconstituted Fibril from Heterogenic Collagens-A New Method to Regulate Properties of Collagen Gels Abstract Heterotypic collagen fibril has long been found in the tissues of organisms, which plays an important role in the formation and function of complex structures of organisms. Inspiring by the phenomenon, scholars tried to incubate collagens from different sources into novel collagen materials in vitro, and the forming of heterogenic reconstituted collagen fibrils (RF) was often demonstrated by differential scanning calorimetry (DSC) and fluorescence quenching analysis. In this work, we used two type-I collagens from different species (bovine tendon and grasscarp fish skin) to co-assemble in vitro, and verified the formation of RF from a new rheological perspective. In addition, we also investigated the assembly behavior, surface hydrophilicity and hydrophobicity, microscopic morphology and cell proliferation ability of the RF. The results showed that the assembly rate, surface properties, fibril size, viscoelastic properties of RF can be delicately regulated by the method of heterogenic collagen reconstitution. This study provides new experimental evidence for the reconstitution of heterogenic collagens, and also offers a new means for the regulation of collagen gel performance, which would help to expand the application range of collagen gel materials.

Tuning with Phosphorylcholine Grafts Improves the Physicochemical Properties of PLL/pDNA Nanoparticles at Neutral pH Abstract The improvement of biological properties of polycations is a fundamental step to overcome their limitations as non-viral gene carriers. This work studied the effect of phosphorylcholine (PC) groups on the physicochemical properties of poly(L-lysine) (PLL)/pDNA nanoparticles. Phosphorylcholine-grafted PLL derivatives (PLL-PC) containing increasing proportions of PC were obtained by the reductive amination reaction with phosphoryl glyceraldehyde and characterized by 1H NMR, FTIR, and GPC measurements. The PLL-PC derivatives were used to prepare polyplexes with pDNA and their properties were evaluated by fluorescence, gel electrophoresis and dynamic light scattering (DLS) measurements. The PLL-PC derivatives were able to interact with pDNA at low N/P ratios in physiological pH to form stable polyplexes having lower zeta potentials, as evidenced by the gel electrophoresis and zeta potentials measurements. A degree of grafting of 10% increased the in vitro transfection efficiency of PLL and a degree of 20 mol% of PC groups provided colloidal stability in physiological saline solution at neutral pH. Overall, the PC-PLL derivatives exhibited improved physicochemical properties and have significant potential for further studies as non-viral gene transfer agents.

Novel Organic/Inorganic Hybrid Star Polymer Surface-Crosslinked with Polyhedral Oligomeric Silsesquioxane Abstract Novel organic/inorganic hybrid star polymer was prepared dually crosslinked within inner-core via divinylbenzene (DVB) and outer-surface via octafunctional polyhedral oligomeric silsesquioxane (POSS). Core cross-linked star polymers bearing dialkynyl-terminated polystyrene arms, (dialkynyl-PS)n-CCL, were synthesized at first by the atom transfer radical polymerization (ATRP) of DVB using α,α-dialkynyl-terminated PS macroinitiator, followed by the subsequent fractionation. Under high dilution conditions, (dialkynyl-PS)n-CCL was subjected to surface cross-linking with octa(3-azidopropyl) polyhedral oligomeric silsesquioxane, POSS-(N3)8, via click reaction, affording POSS-functionalized hybrid polymer doubly cross-linked within core and surface regions, SCL-(PS)n-CCL. FT-IR, 1H NMR, GPC, and elemental analysis results revealed that on average, the obtained hybrid polymer possesses a cross-linked PDVB inner core, ∼14 linear PS arms (the Mw per arm of 5.1 kDa), and ∼4-5 POSS moieties at outer surface. Differential scanning calorimetry (DSC) thermograms and thermogravimetric analysis (TGA) revealed that after surface cross-linking the thermal stability of SCL-(PS)n-CCL is considerably improved. This work provides a proof-of-concept example for the preparation of dually cross-linked hybrid star polymer, which represents a novel category of organic/inorganic composite materials with unique chain architectures.

Surface Properties of Structure-Controlled Silica Films Prepared Using Organic-Inorganic Hybrid Solutions Abstract Silica films with various microstructures were fabricated using organic-inorganic (O-I) hybrid solutions containing a mixture of silica sols, polymethylmethacrylate (PMMA), and urethane acrylate nonionomer (UAN) as an amphiphilic polymer, The O-I hybrid solutions were prepared with various UAN:PMMA and polymer/solvent ratios, then spin-coated on glass and calcinated at 450 °C to produce silica films with various microphase-separated structures. For higher UAN and PMMA concentrations, the silica films showed spherical inorganic domains dispersed over the surface, while many pores were formed in the films with lower polymer contents (observed using scanning electron microscopy). The surface hydrophobicity of the silica films was determined using water contact angle measurements. After surface modification using (1H, 1H, 2H, 2H-perfluorooctyl)trichlorosilane solution, the hydrophobicity of films with a highly microphase-separated structure increased significantly, and all surface-modified films showed increasing hydrophobicity with increasing polymer content. Furthermore, pencil scratch hardness tests showed that the silica films formed on glass substrates could withstand the 5H scratch, test even after surface modification.

Implication of Three Dimensional Framework Architecture of Graphitic Carbon Nanosheets for Improving Electrical Conductivity Under Mechanical Deformation Abstract In this study, based on three-dimensional (3D) framework architecture built-up with two-dimensional (2D) graphitic carbon such as graphene, we have prepared a mechanically robust polymer composite without exhibiting notable deterioration of electrical conductivity under mechanical deformation. In constructing 3D framework comprising of graphitic carbons, two sophisticated methodologies, direct formation of graphitic layers on metal foam by chemical vapor deposition (CVD), and lay-up of reduced graphene oxide (rGO) nanosheets on metal foam have been performed, respectively, and their sustainability of conductive performance under mechanical deformation has been comparatively examined in terms of electrical conductivity change by cyclic mechanical stress. The CVD-synthesized graphene (CGr) framework-embedded PDMS composite, which means a PDMS composite containing 3D graphene framework grown by CVD process, exhibited electrical conductivity of ∼5 S/m at graphene content of 1.0 wt%, which was ∼5 orders of magnitude higher than that of 3D rGO framework-embedded PDMS composite containing comparable loading of rGO. When subjected to repetitive mechanical stress, it was found that the superior conductivity performance of CGr framework over rGO framework was well retained, presumably due to the higher perfectness of graphitic layers, which would impart much longer electron transfer to the framework architecture of graphitic carbon nanosheets.