The Effects of Ferulic Acid, Tryptophan, and L-Glutamine on the Cryopreservation of Mouse Spermatozoa.

In this study, the effects of ferulic acid (0.1, 1, ve 10 mM), tryptophan (5, 25, ve 50 mM), and L-glutamine (10, 50, ve 100 mM) at different doses added to 18% raffinose + 3% skimmed milk powder sperm extender on the freezing of mouse spermatozoa in liquid nitrogen were investigated. The combination of 18% raffinose + 3% skimmed milk powder without additives was used as the control group. Frozen spermatozoa were thawed in a 37°C water bath for 30 seconds. After freeze-thawing, motility, dead spermatozoa ratio, plasma membrane integrity, abnormal acrosome ratio, motility endurance (for 4 hours), and cell apoptosis tests were performed in Human Tubal Fluid (HTF). Compared with the control group after freezing and thawing, the highest motility and plasma membrane integrity were obtained in the 10 mM L-glutamine group with 56.6% ± 2.11% and 77.8% ± 0.87%, respectively (p < 0.05). In addition, when compared to the control group, the lowest rate of dead spermatozoa and abnormal acrosome was found in the 10 mM L-glutamine group as 26.0% ± 1.46% and 6.3% ± 1.09%, respectively (p < 0.05). The highest motility values for spermatozoa endurance were determined in the 10 and 50 mM L-glutamine groups up to the 4th hour compared to the control group (p < 0.05). In the evaluation of apoptosis in semen samples, there was no significant difference between the control, 0.1 mM ferulic acid, and 10 mM L-glutamine groups (p > 0.05). As a result, it was determined that the addition of 10 mM L-glutamine to the spermatozoa extender increased the motility, viable spermatozoa, functional membrane integrity, intact acrosome ratios, or motility endurance after freeze-thawing and could be used successfully in the freezing extender of mouse spermatozoa.

Production of NiMn2O4 hollow spheres and CoFe2O4 bowl-like structures by using block copolymer stabilized polystyrene spheres as a hard template.

The aim of this study is to highlight the use of polystyrene (PS) latexes stabilized with block copolymers as a hard template in the production of metal oxide hollow spheres. PS latexes produced by dispersion polymerization by stabilizing with tertiary amine methacrylate-based diblock copolymer were used as a hard template in the preparation of nickel manganese oxide (NiMn2O4) hollow spheres and cobalt iron oxide (CoFe2O4) bowl-like structures. Thanks to the diblock copolymer stabilizer with tertiary amine functional groups on the PS surface, precursor salts of CoFe2O4 and NiMn2O4 were first homogeneously deposited on the surface of PS latexes with a controlled precipitation technique. Then, metal oxide hollow spheres and bowl-like structures were produced by calcination. XRD results showed that CoFe2O4 and NiMn2O4 structures were successfully obtained after calcination. The thermogravimetric analysis results showed that the CoFe2O4 and NiMn2O4 contents of the hybrid PS spheres were in the range of 26.0-28.6 wt%. SEM images showed that the inorganic-polymer spheres fused with each other after calcination to form larger magnetic CoFe2O4 bowl-like structures. SEM images also indicated successful production of highly rough NiMn2O4 hollow spheres with nanosheets on the surface.

Use of Sulfobetaine-Based Block Copolymer as Stabilizer in Silver Nanoparticle Production and Catalytic Activity Studies.

A zwitterionic sulfobetaine-based diblock copolymer was successfully synthesized and used in the preparation and stabilization of Ag nanoparticles (AgNPs). For the related block copolymer, a precursor AB type diblock copolymer was synthesized via atom transfer radical polymerization by using a MPEG-based ATRP macroinitiator and 2-(N-dimethylamino)ethyl methacrylate (DMA) comonomer. Tertiary amine residues of PDMA blocks in poly(ethylene glycol) methyl ether-b-poly[2-(N-diethylamino)ethyl methacrylate] (MPEG-b-PDMA) precursor was then converted to polybetaine structures by reacting with 1,3-propanesultone to obtain poly(ethylene glycol) methyl ether-b-poly[3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate] (MPEG-b-PßDMA) derivative. The resulting block copolymer was successfully used as stabilizer in the chemical and sonochemical synthesis of spherical AgNPs with a diameter in the range of 7.9-9.3 nm. The average diameter of AgNPs synthesized by sonochemical method was smaller than those synthesized by chemical method. The MPEG-b-PßDMA diblock copolymer was determined to be a good stabilizer for AgNPs. The AgNPs dispersion was stable for more than 5 months without any flocculation at room temperature. The catalytic activity of polymer-AgNP dispersion was also investigated in the reduction of p-nitrophenol to p-aminophenol and was found to be quite effective.