Construction of Sandwich-like cell sheets with natural electrospun gelatin/chitosan nanofibrous delivered plasmid VEGF for accelerated wound healing

Background Development of natural biodegradable electrospun nanofibrous with appropriate physical properties and biocompatibility is highly desirable to support multi-layer cell sheets construction for wound healing. Results We developed a series of electrospun gelatin/chitosan nanofibrous with different gelatin/chitosan ratios and controlled pore sizes, and impregnated plasmid VEGF into membrane, which as supporting membrane to construct sandwich-like adipose-derived stem cells (ADSCs) cell sheets with a simple and effective technique for accelerated wound healing. We found that the physical properties of the electrospun nanofibrous including water retention, stiffness, strength, elasticity and degradation could be tailored by changing the proportion of gelatin/chitosan. We further observed that the optimized electrospun nanofibrous with the optimal ratio of gelatin to chitosan (7:3) which were soft and elastic could most effectively support cell adhesion, proliferation and migration into the whole nanofibrous membranes. Nanofibrous delivered plasmid VEGF facilitating multi-layer ADSC cell sheets formation and promoting regeneration of cutaneous tissues within two weeks. Conclusions Such natural biodegradable and biocompatible electrospun gelatin/chitosan nanofibrous with plasmid have the potential to become fully cellularized and support sandwich-like ADSC cell sheets formation, which will make it suitable for widespread applications such as skin substitute or wound dressing.

Cellulose and Chitosan Composite Membranes for Protein and Salt Filtration

Cellulose membrane (SE) was prepared by culturing Acetobacter xylinum in a media with sucrose as a carbon source and was used as a supporting membrane in this study. Pore size of the supporting membrane was studied by means of molecular weight cut off (MWCO) and SEM micrographs. For making cellulose/chitosan composite membrane SE/CH, chitosan solution was used as a coating polymer and applied by a casting method.This resulted in a smaller hydraulic permeability coefficient (Lp) from 6.7 × 10–11 m3 N–1 s–1 in membrane SE to 1.94 × 10–12 m3 N–1 s–1 in the composite membrane SE/CH. Using PEG of several molecular weights as feed solution, the MWCO of the SE membrane was 200 kDa while that of the SE/CH membrane was 6 kDa. The former rejected 1 g L–1 BSA by 80%. With pH between 3 and 8, the composite membrane SE/CH rejected NaCl and NaHCO3 by 50%, independent of the pH level. However, when using a divalent salt solution of MgSO4 the rejection was increased up to 85%, with an optimum at pH 6–7 and a permeate flux of 5.0 L m–2h–1 at pressures of 0.5 MPa.

Immobilization of laccase on functionalized multiwalled carbon nanotube membranes and application for dye decolorization

Myceliophthora thermophilalaccase was covalently immobilized on functionalized multiwalled carbon nanotubes (MWNT) arranged over a supporting membrane to obtain a permeable bio-barrier that could be applied in multibatch or continuous processes.

Reconstitution of bacteriorhodopsin with cationic poly(dimethylaminoethyl acrylate)-block-poly(methylacrylate) for bio-hybrid materials

A kind of cationic amphiphilic copolymer was synthesized for supporting membrane proteins to prepare bio-hybrid materials.

Nanomechanical torque magnetometry of an individual aggregate of ∼350 nanoparticles

The measurements of magnetic hysteresis for aggregates of nanoparticles deposited on a surface are reported. Magnetite nanoparticles derived from magnetotactic bacteria are studied using nanomechanical torque magnetometry. The nanoparticles are deposited on high-stress Si3N4 membranes, to allow inspection by electron microscopy, followed by focused ion-beam milling of torsional resonators precisely located to capture selected aggregates within the membrane area. Torque magnetometry is performed using the resonators. We investigate also the magnetic torque-driven AC resonant modes of the modified supporting membrane. The observations are compared to numerical simulations of the mechanical modes, and to micromagnetic modeling of the hysteresis of a specific measured cluster of ∼350 nanoparticles.

Yeast vacuolar HOPS, regulated by its kinase, exploits affinities for acidic lipids and Rab:GTP for membrane binding and to catalyze tethering and fusion

Fusion of yeast vacuoles requires the Rab GTPase Ypt7p, four SNAREs (soluble N-ethylmaleimide–sensitive factor attachment protein receptors), the SNARE disassembly chaperones Sec17p/Sec18p, vacuolar lipids, and the Rab-effector complex HOPS (homotypic fusion and vacuole protein sorting). Two HOPS subunits have direct affinity for Ypt7p. Although vacuolar fusion has been reconstituted with purified components, the functional relationships between individual lipids and Ypt7p:GTP have remained unclear. We now report that acidic lipids function with Ypt7p as coreceptors for HOPS, supporting membrane tethering and fusion. After phosphorylation by the vacuolar kinase Yck3p, phospho-HOPS needs both Ypt7p:GTP and acidic lipids to support fusion.

A polymeric ionic liquid functionalized temperature-responsive composite membrane with tunable responsive behavior

A temperature-responsive composite membrane with tunable responsive behavior was obtained by chemically grafting a PIL functionalized temperature-responsive copolymer onto the BPPO supporting membrane.