We have found that antisense oligonucleotides and siRNA molecules modified with repeat structures of disulfide units can be directly introduced into the cytoplasm and exhibit a suppressive effect on gene expression. In this study, we analyzed the mechanism of cellular uptake of these membrane-permeable oligonucleotides (MPONs). Time-course analysis by confocal microscopy showed that the uptake of MPONs from the plasma membrane to the cytoplasm reached 50 % of the total uptake in about 5 min. In addition, analysis of the plasma membrane proteins to which MPONs bind, identified several proteins, including voltage-dependent anion channel. Next, we analyzed the behavior of MPONs in the cell and found them to be abundant in the nucleus as early as 24 h after addition with the amount increasing further after 48 and 72 h. The amount of MPONs was 2.5-fold higher than that of unmodified oligonucleotides in the nucleus after 72 h. We also designed antisense oligonucleotides and evaluated the effect of MPONs on mRNA exon skipping using DMD model cells; MPONs caused exon skipping with 69 % efficiency after 72 h, which was three times higher than the rate of the control. In summary, the high capacity for intracytoplasmic and nuclear translocation of MPONs is expected to be useful for therapeutic strategies targeting exon skipping. 相似文献
Chemical ligation reaction of DNA is useful for the construction of long functional DNA using oligonucleotide fragments that are prepared by solid phase chemical synthesis. However, the unnatural linkage structure formed by the ligation reaction generally impairs the biological function of the resulting ligated DNA. We achieved the complete chemical synthesis of 78 and 258 bp synthetic DNAs via multiple chemical ligation reactions with phosphorothioate and haloacyl-modified DNA fragments. The latter synthetic DNA, coding shRNA for luciferase genes with a designed truncated SV promoter sequence, successfully induced the expected gene silencing effect in HeLa cells. 相似文献
Nano-structural graphite prepared by ball milling under H2 or Ar atmosphere was studied as an electrode for electric double layer capacitors (EDLCs) by means of a conventional 2-electrode galvanostatic method. Especially, the product prepared under H2 atmosphere using zirconia balls revealed 500 m2 g−1 surface area and showed 12 F g−1 specific capacitance, which was comparable to that of an activated carbon with large specific surface area of 3000 m2 g−1 examined as a reference. A proper condition of the milling time is rather a shorter time than ∼8 h, where the graphitic feature is remained in the ball milled product. On the other hand, for the sample prepared by using steel balls, the specific capacitance per surface area was several hundreds times smaller than the others, indicating that the small amount of Fe contamination during milling played a negative role for the EDLC properties. 相似文献
We used a Ca–Bi–Ti complex alkoxide, in which metal–oxygen bonding was confirmed by spectroscopic analysis, to deposit CaBi4Ti4O15 (CBTi144) thin films in various configurations. The phase transition of non-ferroelectric pyrochlore to ferroelectric perovskite in the complex-alkoxy-derived CBTi144 thin films was found to depend on the Pt bottom electrodes. Matching of the atomic arrangement to the Ca–Bi–Ti–O thin films was predominant rather than the strain and crystallinity of the bottom electrode. The thin films crystallized at 650°C on (111)-oriented Pt showed random orientation and ferroelectric P – V hysteresis loops. The endurance property was excellent against a number of switchings. For this reason, CBTi144 thin films would be expected to be excellent for application to ferroelectric random access memories (FeRAM). Polar-axis-oriented CBTi144 films were fabricated on Pt foils using the complex metal alkoxide solution. The 500-nm-thick film had a columnar structure comprising well-developed grains. The a / b -axis orientation of the ferroelectric films is considered to be associated with the preferred orientation of Pt foil. The film showed improved ferro- and piezoelectric properties. The P r, E c, and d 33 values were enhanced to become twice those of CBTi144 thin films with random orientation. These polar-axis-oriented CBTi144 films are eminently useful in devices as Pb-free piezoelectric materials. 相似文献
A new stereo pentablock copolymer consisting of poly(l ‐lactide) (PLLA: A), poly‐d ‐lactide (PDLA: B), and poly(butylene succinate) (PBS: C) is synthesized by two‐step ring‐opening polymerization of d ‐ and l ‐lactides in the presence of bis‐hydroxyl‐terminated PBS prepolymer that has been prepared by the ordinary polycondensation. The pentablock copolymers (PLLA‐PDLA‐PBS‐PDLA‐PLLA) as well as the triblock copolymers (PLLA‐PBS‐PLLA) obtained as the intermediates show different properties depending on the polymer compositions. In the pentablock copolymers, the direct connection of the PLLA and PDLA blocks allows easy formation of the stereocomplex crystals, while the introduction of the semicrystalline PBS block is effective not only for changing the crystallization kinetics but also for imparting an elastomeric property.
For fluidized bed drying under a reduced pressure, the effect of the humidity of the drying gas on the drying characteristics of porous materials immersed in the bed was examined experimentally and theoretically. The temperature at the sample center increased with the humidity at relatively high pressures in the drying chamber (101.3 and 50 kPa), and the degree of the increment in the temperature with the humidity increased with the chamber pressure. The effect of the humidity on the temperature at the sample center and the drying time was insignificant at a relatively low chamber pressure (20 kPa). 相似文献
Poly(L ‐lactide) (PLLA) composites incorporating various inorganic fillers (ifR‐PLA) were prepared by the melt blending technique, and their mechanical and thermal properties were evaluated. The filler types influenced the mechanical properties of ifR‐PLA; for those incorporating particle‐ and whisker‐type fillers the tensile moduli were 3.1–3.7 and 3.7–4.5 GPa, respectively, and the flexural moduli were 4.1–4.8 and 4.8–6.1 GPa. It was found that the tensile strength and modulus, as well as the flexural modulus, of ifR‐PLA incorporating whisker‐type fillers increased in proportion to the volume percent of the fillers (Vf). The flexural strength of ifR‐PLA incorporating 9Al2O3 · 2B2O3 whiskers showed a similar increase, while that of ifR‐PLA incorporating CaCO3 whiskers showed a decrease with increasing Vf. This difference may be because the 9Al2O3 · 2B2O3 with its large aspect ratio kept its original fibrous shape, while the CaCO3 lost its fibrous shape during the blending process. However, the reinforcing effect of these fillers was relatively low compared with that known for the corresponding composites of the conventional polymeric materials, probably because of the poor surface adhesion of PLLA to the fillers.
Comparison of effect on storage moduli of different fillers. 相似文献
Polylactides with high and low L ‐isomeric ratios of the lactate units (PLA99.0 and 77.0, where the numbers correspond to the L ‐ratios) were melt‐blended to analyze the changes in properties and biodegradability with the polymer blend. The crystallinity of the blends was almost similar to that of the blends of PLLA and PDLLA. The glass transition behavior supported the compatibility of both polymers. The glass transition behavior was indicative of a compatible nature of both polymers. The tensile modulus of the blends was almost identical irrespectively of the blend ratio, while their tensile strength decreased with decreasing composition of PLA99.0. Above Tg, the storage modulus of the blends dropped from 2–3×109 Pa to 1–3×106 Pa and then increased to a different level depending on the crystalline nature of the blends. The biodegradability of the blends increased with decreasing composition of PLA99.0. This difference in degradability can be well explained by our random packing model of local helices of the L ‐sequenced chains for the L ‐rich PLA samples. 相似文献
