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The secretome from mesenchymal stem cells (MSCs) have recently gained attention for new therapeutics. However, clinical application requires in vitro cell manufacturing to attain enough cells. Unfortunately, this process often drives MSCs into a senescent state that drastically changes cellular secretion activities. Antioxidants are used to reverse and prevent the propagation of senescence; however, their activity is short‐lived. Polymer‐stabilized crystallization of antioxidants has been shown to improve bioactivity, but the broad crystal size distribution (CSD) significantly increases the efficacy variation. Efforts are made to crystalize drugs in microdroplets to narrow the CSD, but the fraction of drops containing at least one crystal can be as low as 20%. To this end, this study demonstrates that in‐drop thermal cycling of hyaluronic acid‐modified antioxidant crystals, named microcrystal assembly for senescence control (MASC), can drive the fraction of microdrops containing crystals to >86% while achieving significantly narrower CSDs (13 ± 3 µm) than in bulk (35 ± 11 µm). Therefore, this approach considerably improves the practicality of CSD‐control in drops. In addition to exhibiting uniform release, MASC made with antioxidizing N‐acetylcysteine extends the release time by 40%. MASC further improves the restoration of reactive oxygen species homeostasis in MSCs, thus minimizing cellular senescence and preserving desired secretion activities. It is proposed that MASC is broadly useful to controlling senescence of a wide array of therapeutic cells during biomanufacturing. [ABSTRACT FROM AUTHOR]

Cellulose is a well-known versatile polymer that presents a wide range of material properties via the substitution and grafting reactions of its hydroxyl groups. Because of their commercial potential, combinations of cellulose and vinyl polymers have been examined with various grafting methods. In this study, the condensation reactions of regioselective and nonregioselective substitution with 2-isocyanatoethylmethacrylate were performed in a homogeneous solvent system of dimethyl acetamide/lithium chloride. The successful substitution was confirmed by Fourier transform infrared spectroscopy, 1H-NMR, cross-polarization/magic angle spinning 13C-NMR, thermogravimetric analysis, and X-ray diffraction. The substituted celluloses showed excellent thermal stability and a different polymorph with a depressed cellulose-intrinsic polymorphic phase. The 2-isocyanatoethylmethacrylate side chain seemed to expand the intermolecular distance with enhanced chain mobility and trigger the formation of a novel crystalline polymorph with a dramatically improved thermal stability. This investigation provided us with a useful understanding of the modification of cellulose with spatial distribution control for advanced future applications requiring a combination of cellulose with vinyl polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

The article analyzes the impacts of electrospraying parameters on morphological and dimensional changes of solidified polymer particles. Results reveal that between the two particle-formation steps, namely, liquid droplet formation and subsequent solidification, the latter influenced the final particle morphology. The concentration disparities between the surface and center region of a droplet spurred the formation of skin layers.

The reduction of particle size to nanometers has been an important tool used for efficient drug delivery. Solid drug nanoparticles can be conveniently prepared by nanocomminution. This process relies on mechanical energy and the selection of a proper polymeric stabilizer. The long chains of polymers provide steric stabilization for drug nanoparticles. In this research, itraconazole and hydroxypropyl cellulose were used to study the effect of the molecular weight of a polymer on particle size reduction. In principle, an increase in molecular weight produces two counteracting effects: a decrease in the diffusion rate of chains and an increase in the physical adsorption of a polymer. The effects of particle size reduction are more pronounced in systems involving smaller molecular weights, and the effects of changing molecular weights disappear with time. Systems of higher molecular weight show larger aggregates in their redispersion after drying. Based on the results of our research, it appears that polymers of smaller molecular weight are more suitable than larger polymers for efficient nanocomminution. This indicates that the kinetic aspects of molecular weight are important. [ABSTRACT FROM AUTHOR]

Engineering the surface properties of a material without affecting its bulk properties is desirable for many applications, but it is often not readily achievable because it requires a complex series of processing steps. This study presents for the first time a simple and straightforward method that can convert regular flat polymer surfaces into various porous composite surfaces. The controlled dissolution of the polymer surface by a dispersion and subsequent melt crystallization allows for the successful embedding of dispersed inorganic or organic particles in the pore walls. The porous surface morphology is not significantly affected by the type of dispersed particle, but the contact and sliding angles and surface wettability are. Both superhydrophobic and oil/water separation surfaces can be conveniently fabricated from flat polymer surfaces. This novel and versatile technique could provide engineering freedom for the future development of various functional materials. [ABSTRACT FROM AUTHOR]

Porous materials with surprisingly diverse structures have been utilized in nature for many functional purposes. However, the structures and applications of porous man-made polymer materials have been limited by the use of processing techniques involving foaming agents. Herein, we demonstrate for the first time the outstanding hardness and modulus properties of an elastomer that originate from the novel processing approach applied. Polyurethane films of 100-μm thickness with biomimetic ordered porous structures were prepared using directional melt crystallization of a solvent and exhibited hardness and modulus values that were 6.8 and 4.3 times higher than those of the random pore structure, respectively. These values surpass the theoretical prediction of the typical model for porous materials, which works reasonably well for random pores but not for directional pores. Both the ordered and random pore structures exhibited similar porosities and pore sizes, which decreased with increasing solution concentration. This unexpectedly significant improvement of the hardness and modulus could open up new application areas for porous polymeric materials using this relatively novel processing technique. [ABSTRACT FROM AUTHOR]

Abstract: Recently, researchers have tried to produce non-spherical and anisotropic particles to be used in the next generation of multi-functional materials. Of key interest is the red blood cell-like particle. The torus structure was produced under the relatively fast consolidation of monodisperse droplets, and its parameters were found to be tunable by temperature as well as solvent type and concentration. The observation of consolidation demonstrated that the polymers were accumulated and solidified in the torus structure, naturally, whereas there was the critical droplet size to induce the asymmetry diffusivities. The torus structures could be simply tuned by the flow rate and concentration. The coaxial nozzle system produced the core/shell torus particles. These results state that the consolidation mechanism can hold important clues to enhance the range of tuning capabilities. [Copyright &y& Elsevier]

Living organisms secrete minerals composed of peptides and proteins, resulting in 'mesocrystals' of three-dimensional-assembled composite structures. Recently, this biomimetic polymer-directed crystallization technique has been widely applied to inorganic materials, although it has seldom been used with drugs. In this study, the technique was applied to the drowning-out crystallization of atorvastatin using various polymers. Nucleation and growth at optimized conditions successfully produced composite crystals with significant polymer contents and unusual characteristics. Atorvastatin composite crystals containing polyethylene glycol, polyacrylic acid, polyethylene imine, and chitosan showed a markedly decreased melting point and heat of fusion, improved stability, and sustained-release patterns. The use of hydroxypropyl cellulose yielded a unique combination of enhanced in vitro release and improved drug stability under a forced degradation condition. The formation hypothesis of unique mesocrystal structures was strongly supported by an X-ray diffraction pattern and substantial melting point reduction. This polymer-directed crystallization technique offers a novel and effective way, different from the solid dispersion approach, to engineer the release, stability, and processability of drug crystals. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:2941-2951, 2012 [ABSTRACT FROM AUTHOR]

Abstract: Nanoparticle engineering of drug crystals is an important basic tool for efficient and intelligent drug delivery. Recently, the wet comminution process of drug nanocrystals in the presence of polymeric stabilizers has been successfully developed, but it has not been well understood yet how to select a proper stabilizer for a drug. In this study, the nature of interactions between polymeric stabilizers and drugs was investigated by analyzing the steady state particle sizes of 7 drugs obtained by wet comminution. The surface energy of drugs and polymers measured by contact angle measurement was found to be an important factor, although it could not solely determine the steady state values of particle size. In addition to surface energy, specific interactions between functional groups appeared to play a certain role. The stabilization ability of polymers and the subsequent steady state particle size of drug nanocrystals depend on various parameters including surface energy and specific interactions. [Copyright &y& Elsevier]