No abstract

MSC-Derived EV Production in Bioreactors concentration (i.e., EV concentration in the conditioned medium) (5.7-fold increase overall) and productivity (i.e., amount of EVs generated per cell) (3-fold increase overall). BM, AT and UCM MSC cultured in the VWBR system yielded an average of 2.8 ± 0.1 × 10 11 , 3.1 ± 1.3 × 10 11 , and 4.1 ± 1.7 × 10 11 EV particles (n = 3), respectively, in a 60 mL final volume. This bioreactor system also allowed to obtain a more robust MSC-EV production, regarding their purity, compared to static culture. Overall, we demonstrate that this scalable culture system can robustly manufacture EVs from MSC derived from different tissue sources, toward the development of novel therapeutic products.

The formation of solid films from latex dispersions is studied using particles labeled with phenanthrene or anthracene comprised of either poly(n-butyl methacrylate) (PBMA) or a copolymer of n-butyl methacrylate with a poly(ethylene oxide) (PEO) macromonomer, co(PBMA-PEO). Interparticle polymer diffusion was followed by nonradiative electronic energy transfer (DET) between electronically excited phenanthrene and anthracene. A model of energy transfer that considers both the topological constraints and the heterogeneous distributions of donors and acceptors is presented. The analysis of the phenanthrene decay curves allows calculation of the diffusion coefficient as a unique parameter, for several annealing times. The values recovered decrease initially with annealing time, which was attributed mainly to the polydispersity of the PBMA. The addition of a small percentage of low molecular weight PEO (in the form of nonylphenolethoxylate) to the PBMA particles increases the diffusion coefficient, this effect resulting from the increase of the polymer free volume in the film. When the same percentage of PEO is incorporated in the PBMA polymer chain in the form of a grafted macromonomer, the fraction of mixing increases on drying, but during annealing the diffusion coefficients remain equal to that of PBMA without PEO.

The development of packaging materials with new functionalities and lower environmental impact is now an urgent need of our society. On one hand, the shelf-life extension of packaged products can be an answer to the exponential increase of worldwide demand for food. On the other hand, uncertainty of crude oil prices and reserves has imposed the necessity to find raw materials to replace oil-derived polymers. Additionally, consumers' awareness toward environmental issues increasingly pushes industries to look with renewed interest to "green" solutions. In response to these issues, numerous polymers have been exploited to develop biodegradable food packaging materials. Although the use of biopolymers has been limited due to their poor mechanical and barrier properties, these can be enhanced by adding reinforcing nanosized components to form nanocomposites. Cellulose is probably the most used and well-known renewable and sustainable raw material. The mechanical properties, reinforcing capabilities, abundance, low density, and biodegradability of nanosized cellulose make it an ideal candidate for polymer nanocomposites processing. Here we review the potential applications of cellulose based nanocomposites in food packaging materials, highlighting the several types of biopolymers with nanocellulose fillers that have been used to form bio-nanocomposite materials. The trends in nanocellulose packaging applications are also addressed.

We propose a model to describe energy transfer between donors and acceptors chemically attached to the two different components of a polymer blend. The model describes the case of one polymer dispersed as spheres of identical diameter in a continuous matrix of the second polymer. The model takes explicit account of the segment distribution of the two polymers in the interface region. We used this model to characterize the interface between poly(butyl methacrylate) (PBMA) and poly(2-ethylhexyl methacrylate) (PEHMA) domains in a binary blend. The blend was prepared by casting films onto a solid substrate from mixed aqueous latex dispersions of the two polymers. The dispersions were prepared by emulsion polymerization under conditions in which both components were formed as spherical particles with a very narrow size distribution. By using a 14:1 particle ratio of PEHMA to PBMA, we obtained films in which the 120 nm PBMA particles were surrounded by the PEHMA matrix. For the ion-exchanged latex blend, the interface thickness in the film freshly prepared at room temperature was δ ) 21 ( 2 nm and upon annealing broadened to δ ) 25 ( 2 nm. Because of the low degrees of polymerization for the samples, it is difficult to have confidence in the value of the Flory-Huggins parameter χ calculated from the experimental value of δ, because the correction for the finite length of the component is larger than the term that depends on the interface width. Keeping in mind the limitations of this calculation, we estimate that χ is approximately equal to 0.02-0.03.