Multivalent bonds in self-assembled bundles of ultrathin gold nanowires.

Ultrathin gold nanowires are unusual colloidal objects that assemble into bundles with line contacts between parallel wires. Each molecule in the contact line interacts with many ligand and solvent molecules. We used X-ray scattering and electron microscopy to study how these interactions control assembly.

Gold nanorods with conjugated polymer ligands: sintering-free conductive inks for printed electronics.

Metal-based nanoparticle inks for printed electronics usually require sintering to improve the poor electron transport at particle-particle interfaces. The ligands required for colloidal stability act as insulating barriers and must be removed in a post-deposition sintering step. This complicates the fabrication process and makes it incompatible with many flexible substrates. Here, we bind a conjugated, electrically conductive polymer on gold nanorods (AuNRs) as a ligand. The polymer, poly[2-(3-thienyl)-ethyloxy-4-butylsulfonate] (PTEBS), provides colloidal stability and good electron transport properties to stable, sintering-free inks. We confirm that the polymer binds strongly through a multidentate binding motif and provides superior colloidal stability in polar solvents over months by IR and Raman spectrometry and zeta potential measurements. We demonstrate that the developed ligand exchange protocol is directly applicable to other polythiophenes such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). Films of AuNRs coated with above polymers reached conductivities directly after deposition comparable to conventional metal inks after ligand removal and retained their conductivity for at least one year when stored under ambient conditions.

The effect of aqueous progesterone on operative adhesion formation.

Progesterone (P) has been shown to have antiinflammatory and immunosuppressive properties. This study was designed to evaluate these effects on operative adhesion formation. Forty guinea pigs received standardized injuries to their uterine horns. Four groups were examined. Normal saline was used as an irrigant in the first, or control, group. Aqueous P (50 mg or 1 ml) was dripped over the injured site and instilled intraperitoneally in the second group. The third group received intramuscular aqueous P (3.3 mg/kg body weight) 1 day postoperatively, the day of surgery, and either 6 or 13 days postoperatively until reexploration. In the fourth group 1 ml of 32% dextran 70 (Hyskon) was administered in the same manner as aqueous P in the second group. The animals in all groups were reexplored 1 or 2 weeks after the initial surgical procedure, and the adhesions were scored. Adhesion formation was significantly reduced (P less than 0.001) in all treatment groups when compared with the control group. Aqueous P may have a role in the prevention of adhesion formation associated with pelvic surgery and, in particular, microscopic tubal and ovarian surgery.