DNA-gold nanorod conjugates for remote control of localized gene expression by near infrared irradiation

Gold nanorods were attached to the gene of enhanced green fluorescence protein (EGFP) for the remote control of gene expression in living cells. The UV-vis spectroscopy, electrophoresis, and transmission electron microscopy (TEM) were used to study the optical and structural properties of the EGFP DNA and gold nanorod (EGFP-GNR) conjugates before and after femto-second near-infrared (NIR) laser irradiation. Upon NIR irradiation, the gold nanorods of EGFP-GNR conjugates underwent shape transformation that resulted in the release of EGFP DNA. When EGFP-GNR conjugates were delivered to cultured HeLa cells, induced GFP expression was specifically observed in cells that were locally exposed to NIR irradiation. Our results demonstrate the feasibility of using gold nanorods and NIR irradiation as means of remote control of gene expression in specific cells. This approach has potential applications in biological and medical studies.     

Syntheses and X-ray structures of some pyrrolylaldiminate metal complexes

Several pyrrolylaldiminate complexes of Group 1, 4 and 13 metals are reported. The reaction of 5-tert-butyl-2-[(2,6-diisopropylphenyl)aldimino]pyrrole (HL) with NaH produced LNa(THF) (1). In situ lithiation of HL followed by addition of one equivalent of MCl_x (M=Zr, x=4; M=Hf, x=4, M=Al, x=3) afforded the corresponding pyrrolylaldiminate complexes, MLCl₂(μ-Cl)₂Li(OEt₂)₂ (M=Zr, 3; Hf, 4) and AlLCl₂ (5). Alkylation of 5 with MeMgBr generated AlLMe₂ (6). In addition to the spectroscopic data, complexes 3-6 were characterized by X-ray crystallography.     

Effect of Y2O3 addition on the phase transition and growth of YSZ nanocrystallites prepared by a sol-gel process

The effect of Y₂O₃ addition on the phase transition and growth of yttria-stabilized zirconia (YSZ) nanocrystallites prepared by a sol-gel process with various mixtures of ZrOCl₂ · 8H₂O and Y(NO₃)₃ · 6H₂O ethanol-water solutions at low temperatures has been studied. DTA/TGA, XRD, SEM, TEM and ED have been utilized to characterize the YSZ nanocrystallites. The crystallization temperature of 3YSZ, in which Y₂O₃/(Y₂O₃ + ZrO₂) = 0.03, gel powders estimated by DTA/TG is about 427 °C. When 3YSZ and 5YSZ gels are calcined at 500-700 °C, their crystal structures as composed of coexisting tetragonal and monoclinic ZrO₂, and tetragonal phase decreases with calcination temperature increasing from 500 to 700 °C. Pure cubic ZrO₂ is obtained when added Y₂O₃ is greater than 8 mol%. A nanocrystallite size distribution between 10 and 20 nm is obtained in TEM observations.     

New A-A-D-A-A-type electron donors for small molecule organic solar cells

Two A-A-D-A-A-type molecules (BCNDTS and BDCDTS), where two terminal electron-withdrawing cyano or dicyanovinylene moieties are connected to a central dithienosilole core through another electron-accepting 2,1,3-benzothiadiazole block, have been synthesized, characterized, and employed as electron donors for small molecule organic solar cells. Vacuum-deposited bilayer and planar mixed heterojunction devices based on BCNDTS and fullerene acceptors (C(60) or C(70)) exhibited decent power conversion efficiencies of 2.3% and 3.7%, respectively.     

Efficient Synthesis of New Peptidyl Chloromethyl Ketones for the Application of Proteinase K Inhibitors

The synthesis of a new series of peptidyl chloromethyl ketones such as MeOSuc-Ala-Ala-Pro-Ile-CH₂Cl (AAPI) and MeOSuc-Ala-Ala-Ala-Pro-Ile-CH₂Cl (AAAPI) is described.     

Clay-mediated synthesis of silver nanoparticles exhibiting low-temperature melting

Nanohybrids of silver nanoparticles (AgNPs) supported on mica clay were synthesized by in situ reduction of silver nitrate in an aqueous solution. The required mica platelets of high aspect ratio were previously prepared by the exfoliation of mica clay stacks in a multilayered structure through an ionic exchange reaction with poly(oxypropylene)-amine-salt. The exfoliated nanoscale mica platelets (Mica) are polydispersed such that each platelet is 300-1000 nm in width and 1 nm in thickness. These platelets possess ionic charges in the form of ≡SiO(-)Na(+) at 120 mequiv/100 g and are suitable for supporting AgNPs in the process of in situ reduction of silver nitrate. Transmission electronic microscopy revealed the formation of AgNPs with a narrow size distribution of ca. 8 nm in diameter on the rim of individual Mica platelets. However, the pristine layered Mica structure without exfoliation failed to produce a fine AgNP distribution but instead generated particles larger than 30 nm and some precipitates. Characterization by differential scanning calorimetry and field emission scanning electron microscopy revealed that the fine AgNPs on Mica platelets exhibited a low melting temperature of 110 °C. The AgNP/Mica nanohybrid not containing an organic dispersant is considered to be a "naked" silver particle.