Development of Poly-NIsopropylacrylamide Surfaces for the Selection of Swine Sperm

The reproductive efficiency of pig farms is directly correlated with the fertility of the boars. The aim of this work was to develop polymeric materials that can be used as a platform to select a subpopulation of sperm with better cell physiological parameters. Polymeric hydrogels composed of Poly-N-isopropylacrylamide with different positive charges given by copolymerization with (3-acrylamidopropyl) trimethylammonium chloride (APTA, 5-10-15%), were synthesized. Subsequently, the interaction between the sperm cells and the polymeric surfaces was analyzed in TALP medium. Release of the spermatozoa from the polymeric surfaces was induced by changing to Ca2+ free media. Sperm motility, cell viability, plasma membrane and acrosome integrity were evaluated. The results indicated that a higher percentage of swine sperm attached to PNIPAM co-15% APTA hydrogels (62.86±3.33%). Ninety seven percent (97.19±1.45 %) of the sperm released from the PNIPAM co-15%APTA surfaces were viable (p<0.05 vs unbound population and raw semen), with acceptable motility (58.89±1.28%) and with intact plasma and acrosomal membranes (69±1.2% and 98.5±0.65% respectively). These results indicate that hydrogels can be used to select boar sperm with high viability and mobility for use in assisted reproductive techniques.

Aza-Reversine Promotes Reprogramming of Lung (MRC-5) and Differentiation of Mesenchymal Cells into Osteoblasts

Reversine or 2-(4-morpholinoanilino)-N6-cyclohexyladenine was originally identified as a small organic molecule that induces dedifferentiation of lineage-committed mouse myoblasts, C2C12, and redirects them into lipocytes or osteoblasts under lineage-specific conditions (LISCs). Further, it was proven that this small molecule can induce cell cycle arrest and apoptosis and thus selectively lead cancer cells to cell death. Further studies demonstrated that reversine, and more specifically the C2 position of the purine ring, can tolerate a wide range of substitutions without activity loss. In this study, a piperazine analog of reversine, also known as aza-reversine, and a biotinylated derivative of aza-reversine were synthesized, and their potential medical applications were investigated by transforming the endoderm originates fetal lung cells (MRC-5) into the mesoderm originated osteoblasts and by differentiating mesenchymal cells into osteoblasts. Moreover, the reprogramming capacity of aza-reversine and biotinylated aza-reversine was investigated against MRC-5 cells and mesenchymal cells after the immobilization on PMMA/HEMA polymeric surfaces. The results showed that both aza-reversine and the biofunctionalized, biotinylated analog induced the reprogramming of MRC-5 cells to a more primitive, pluripotent state and can further transform them into osteoblasts under osteogenic culture conditions. These molecules also induced the differentiation of dental and adipose mesenchymal cells to osteoblasts. Thus, the possibility to load a small molecule with useful “information” for delivering that into specific cell targets opens new therapeutic personalized applications.

Engineered Bioactive Polymeric Surfaces by Radiation Induced Graft Copolymerization: Strategies and Applications

The interest in developing antimicrobial surfaces is currently surging with the rise in global infectious disease events. Radiation-induced graft copolymerization (RIGC) is a powerful technique enabling permanent tunable and desired surface modifications imparting antimicrobial properties to polymer substrates to prevent disease transmission and provide safer biomaterials and healthcare products. This review aims to provide a broader perspective of the progress taking place in strategies for designing various antimicrobial polymeric surfaces using RIGC methods and their applications in medical devices, healthcare, textile, tissue engineering and food packing. Particularly, the use of UV, plasma, electron beam (EB) and γ-rays for biocides covalent immobilization to various polymers surfaces including nonwoven fabrics, films, nanofibers, nanocomposites, catheters, sutures, wound dressing patches and contact lenses is reviewed. The different strategies to enhance the grafted antimicrobial properties are discussed with an emphasis on the emerging approach of in-situ formation of metal nanoparticles (NPs) in radiation grafted substrates. The current applications of the polymers with antimicrobial surfaces are discussed together with their future research directions. It is expected that this review would attract attention of researchers and scientists to realize the merits of RIGC in developing timely, necessary antimicrobial materials to mitigate the fast-growing microbial activities and promote hygienic lifestyles.

Comparison of the Growth and Thermal Properties of Nonwoven Polymers after Atomic Layer Deposition and Vapor Phase Infiltration

The growth mechanism of Atomic Layer Deposition (ALD) on polymeric surfaces differs from growth on inorganic solid substrates, such as silicon wafer or glass. In this paper, we report the growth experiments of Al2O3 and ZnO on nonwoven poly-L-lactic acid (PLLA), polyethersulphone (PES) and cellulose acetate (CA) fibres. Material growth in both ALD and infiltration mode was studied. The structures were examined with a scanning electron microscope (SEM), scanning transmission electron microscope (STEM), attenuated total reflectance-fourier-transform infrared spectroscopy (ATR-FTIR) and 27Al nuclear magnetic resonance (NMR). Furthermore, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis were used to explore the effect of ALD deposition on the thermal properties of the CA polymer. According to the SEM, STEM and ATR-FTIR analysis, the growth of Al2O3 was more uniform than ZnO on each of the polymers studied. In addition, according to ATR-FTIR spectroscopy, the infiltration resulted in interactions between the polymers and the ALD precursors. Thermal analysis (TGA/DSC) revealed a slower depolymerization process and better thermal resistance upon heating both in ALD-coated and infiltrated fibres, more pronounced on the latter type of structures, as seen from smaller endothermic peaks on TA.