Functionalization of emissive conjugated polymer nanoparticles by coprecipitation: consequences for particle photophysics and colloidal properties.

The functionalization of polyfluorene (PFO) nanoparticles by coprecipitation of the conjugated polymer with an amphiphilic comb polymer, consisting of a hydrophobic polystyrene backbone with hydrophilic, carboxylic acid-terminated polyethylene oxide side-chains (PS-PEG-COOH), is investigated. The comb polymer affects the properties of the formed hybrid nanoparticles. Non-functionalized particles are typically larger (28 nm) than functionalized ones (20 nm); peak molar extinction coefficients are found to differ in a similar trend. Zeta potentials are negative, consistent with negative surface charge on PFO particles due to chemical defect formation, with additional charge on functionalized particles due to the pendant carboxylic acid groups. Emission quantum yields of functionalized particles are typically larger, consistent with lower efficiency of energy transfer to quenchers in smaller particles and weaker PFO interchain interactions due to chain dilution. The trend in per-particle fluorescence brightness values, as confirmed by single particle fluorescence imaging, reflects the nanoparticle extinction coefficients. Photostability studies on aqueous dispersions of hybrid particles indicate mild photobrightening under continuous illumination while PFO particles exhibit slow exponential emission decay. Functionalized particles are also resistant to aggregation during exposure to adenocarcinoma cells. Generally, the hybrid particles exhibit more favorable time-, pH- and medium-dependent stabilities, likely due to steric and electrostatic stabilization by PEG-carboxylic acid functionalities. Overall, the functionalized particles exhibit attractive properties: Reasonably small size, tight size distribution, high absorption cross section, radiative rate and emission quantum yield, excellent brightness and photostability, and good colloidal stability.

Surfactant-free, low band gap conjugated polymer nanoparticles and polymer:fullerene nanohybrids with potential for organic photovoltaics.

Stable, aqueous dispersions of nanoparticles based on the low band gap polymers poly [2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (APFO-3) and poly [N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) were prepared, using a flexible, surfactant-free reprecipitation method, and characterized by a variety of optical techniques. Light scattering measurements indicated average nanoparticle hydrodynamic diameters of approximately 40 nm. The particles presented wide-bandwidth absorption and photoluminescence excitation spectra with high absorption cross-sections on the order of 10(-12) cm(2). Nanoparticle emission spectra were significantly red-shifted, with decreased emission quantum yields and lifetimes, consistent with increased inter-polymer chain interactions in the condensed phase. Single particle photoluminescence studies highlighted the multi-chromophoric nature of the polymer nanoparticles and confirmed their favorable photostabilities. When the nanoparticles were doped with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), the correspondence of photoluminescence emission quenching, quantum yield decreases, emission lifetime shortening, and increased non-radiative rates with increasing PCBM concentration suggested efficient photo-induced donor-to-acceptor charge transfer between the conjugated polymers and the fullerene dopants co-localized in the nanoparticle cores. Taken together, the data suggest that these surfactant-free hybrid nanomaterials may be useful for integration with future nanostructured organic photovoltaics technologies.

Verification of the Australian Orthopaedic Association National Joint Replacement Registry using a surgeon's database.

PURPOSE: To assess the completeness of registration and any discrepancies between the senior author's database and the Australian Orthopaedic Association National Joint Replacement Registry (AOA NJRR). METHODS: From 2002 to 2005, the senior author performed 231 primary total hip arthroplasty (THA) on 217 patients using the Corail femoral stem and one of the 3 types of the acetabular component: Pinnacle, ASR, or Duraloc/Option. The name of each patient was forwarded to the AOA NJRR for matching and verification. RESULTS: The AOA NJRR recorded 230 of the 231 primary THAs; all but one was matched with the senior author's database. Nine (3.9%) of them were revised by the same (n=7) or another (n=2) surgeon. Three (43%) of the 7 revision surgeries were not recorded on the AOA NJRR. One patient revised for a ceramic liner fracture was incorrectly recorded as 'wear acetabulum' in the AOA NJRR. CONCLUSION: Although the AOA NJRR achieved high registration completeness for primary THA, accuracy for revision THA was much lower.

Surgical repair of the gluteal tendons: a report of 72 cases.

Lateral hip pain is a common problem in middle-aged women. This pain is usually attributed to trochanteric bursitis and treated as such. This study reports the results of investigation, the findings at surgery, the operative technique, the histopathologic findings, and the results of gluteal tendon repair in 72 patients with long-standing trochanteric pain and reports a classification of the operative findings. Six patients (7%) in the original study cohort of 89 patients were lost to follow-up, but of the remaining patients, 65 of 72, or 90%, were pain-free or had minimal pain (P < .00001). Surgical reconstruction of detached gluteal tendons causing chronic lateral hip pain addresses the problem directly and reliably relieves the symptoms of so-called "trochanteric bursitis."