Equine Spermatozoa Selection by Magnetic Activation for Use in Assisted Reproduction.

This study aimed to select high-quality spermatozoa by sperm separation by magnetic activation of the fresh equine semen, compared to density gradient centrifugation and evaluating cell quality after selection. The semen of 10 stallions was collected by the artificial vagina technique. The samples analyzed were: (1) fresh semen; (2) density gradient centrifugation (DGC); (3) separation by magnetic activation (MASS) (nonapoptotic portion NAP); (4) separation by MASS (apoptotic portion-APT). Was analyzed: motility (light microscopy), concentration (Neubauer chamber), semen morphology (humid chamber in phase contrast), and supravital test (eosin/nigrosine). In DGC, 20 × 106 spermatozoa were used in the gradient of Percoll at 90% and 45% (400 µL each), centrifugation at 900 G/5 min, the pellet was diluted in HEPES. In MASS, 10 × 106 spermatozoa were diluted in 1.5 mL of HEPES, centrifugation at 300 G/10 min, pellet was resuspended in 150 µL of HEPES with 20 µL of nanoparticles bound to annexin V, incubation for 15 minutes and filtered in the magnetic separation column. The nonapoptotic fraction was collected directly and the apoptotic fraction after removal the column from the magnet and adding 300 µL of HEPES. The total abnormalities were 43.2% ± 2.78%, with the DGC and MASS being effective in reducing sperm abnormality by 15.6% ± 2.10% and 24.30% ± 1.63%, respectively, like the observed for the number of cells with intact membranes (50% lower in the APT portion). This nanotechnological method is efficient in producing high-quality semen samples for assisted reproduction procedures.

Optical spectroscopy study of the interaction between curcumin and acrylic polymers.

This paper presents the results of a study conducted on the interaction between curcumin, a compound with several biomedical applications in traditional and modern medicine, and the acrylic polymers poly(methyl methacrylate), poly(ethyl methacrylate), and poly(n-butyl methacrylate), through photophysical experiments in curcumin/acrylic polymers casting films. Optical absorption intensity at ~340 nm increases relatively to its maximum at ~417 nm when the amount of curcumin in the polymeric film decreases, due to a significant change in the concentration of the isomers cis- or trans-form of curcumin, regardless of the acrylic polymer. Fluorescence (FL) spectra of the films depend on the curcumin concentration in the matrix with well-resolved line shape. They show two distinct bands, one at ~525 nm, for higher curcumin concentration (5.00 mmol.L-1), related to the aggregated curcumin species, and another at ~465 nm, for lower concentration of curcumin (0.10 mmol.L-1), related to the effects of the solvent on the conformational structure of the curcumin molecule and the presence of the trans-form of curcumin. The parameter Kagg, related to the contribution of the aggregated curcumin, shows the influence of the polymeric lateral chain length of the matrix in the de-aggregation of the curcumin. The Huang-Rhys factor indicates that curcumin aggregated species are conformationally more stable, and that the isolate species depends on the chemical environment and the matrix/curcumin interaction, decreasing its conformational degrees of freedom. Arrhenius plots, obtained via FL experiment in function of the sample temperature, show that, for higher curcumin concentration, the value for the relaxation energy process is not well defined, due the decrease in the interaction between the matrix and the curcumin molecules. With these results, it is possible to infer that the interaction matrix/curcumin must occur via lateral chemical alkyl groups.

Decoupling Temperature-Volume Effects on Poly[2-Methoxy-5-(2'-Ethylhexyloxy)-1,4-Phenylene-Vinylene] Films at the ß-Relaxation Temperature.

In this paper, we report a simple procedure to decouple effects from temperature and volume on the emission properties of thin films of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene-vinylene] (MEH-PPV). This procedure consists of applying a positive pressure close to the ß-relaxation temperature, Tß (∼220 K), of MEH-PPV, which controls the molecular movement to retain a disordered state for the polymer chains even after the sample is cooled from room temperature. Such decoupling could be confirmed by calculating the photoluminescence (PL) spectra line shape using a semi-empirical model based on molecular exciton and Franck-Condon transitions, and with electron-vibrational modes coupling being parameterized with the Huang-Rhys factor. We also show that the decoupling between temperature and volume effects does not occur if the molecular movement is restricted either by thermal annealing or by depositing the MEH-PPV film on a rigid substrate. This latter finding may be exploited in designing thermally stable devices.

Nanomolding the Surface of Polymer Films.

Slight changes in the experimental procedures of the micro contact printing (ACP) technique are introduced here, which allow for using polymers soluble in distinct solvents to fabricate submicrometric 2D periodic structures. Highly reproducible secondary and tertiary poly(dimethylsiloxane) (PDMS) molds could be produced, as demonstrated in atomic force microscopy images and light diffraction experiments. The replication of tertiary molds with no residues of PDMS demonstrates the feasibility of large-scale production with distinct polymers. The plane wave propagation along the tertiary poly(3,4-ethylenedioxythiophene) with poly(hydrogen 4-styrene sulfonate) molds was simulated with a finite-difference time-domain algorithm. A strong wave propagation was observed in the region containing the structures acting as a wave guide, in agreement with the results from the experimental absorption measurements. Furthermore, we show that the optical properties of the molds and their roughness can be tuned by choosing the polymers (including biopolymers) for printing pillars and tracks, thus bringing new possibilities for nanomolding of polymer surfaces for photonics, organic electronics and bioelectronics.

The effect of the layer structure on the activity of immobilized enzymes in ultrathin films.

The molecular engineering capability of the layer-by-layer (LbL) method for fabricating thin films has been exploited in order to immobilize glucose oxidase (GOD) in films with alternating layers of chitosan. Chitosan was proven a good scaffolding material, as GOD molecules preserved their catalytic activity towards glucose oxidation. Using electrochemical measurements, we showed that chitosan/GOD LbL films can be used to detect glucose with a limit of detection of 0.2 mmol l-1 and an activity of 40.5 microA mmol-1 L microg-1, which is highly sensitive when compared to other sensors in previous reports in the literature. The highest sensitivity of the LbL film was achieved when only the top layer contained GOD, thus indicating that GOD in inner layers did not contribute to glucose oxidation, probably because it hampers analyte diffusion and electron transport through the deposited layers. This may be explained by the dense packing of GOD molecules in the LbL films with chitosan, as inferred from estimates of the amount of GOD adsorbed per layer using a quartz crystal microbalance.