A facile method to functionalize gold nano-tripods with high suspension stability in an aqueous environment.

Here we aim to develop a facile emulsion-based method to prepare tripod gold nanoparticles (AuNPs) with high suspension stability in an aqueous environment. A gyroid-structured polymer template formed by the hydrolysis of a degradable block copolymer, polystyrene (PS)-b-poly(l-lactide), is used for the fabrication of AuNPs. Also, a successful emulsification of dichloromethane (DCM) in the aqueous phase is developed by using thiolated polyethylene glycol (PEG-SH) as the stabilizer. Subsequently, the nanohybrids of PS/Au can be fabricated by templated electroless plating, and then selectively dissolving in the DCM dispersive phase. Most interestingly, a dedicated process for the simultaneous release of the tripod AuNPs from the dissolution of PS associated with PEG-SH at the interface of the emulsion is achieved, giving PEG-SH-functionalized tripod AuNPs dispersed in the aqueous phase, which significantly improves the suspension stabilization of tripod AuNPs. The in situ temperature-programmed electrospray-differential mobility analysis provides a quantitative, statistical analysis of mobility diameter, dynamic shape factor, polydispersity, and colloidal stability.

Aggregation kinetics of colloidal particles measured by gas-phase differential mobility analysis.

We demonstrate the utility of electrospray gas-phase ion-mobility analysis as a new method to investigate nanoparticle flocculation, or aggregation. Au nanoparticle (Au-NP) solutions were sampled via electrospray (ES), followed by differential ion-mobility analysis (DMA) to determine the particle mobility distribution. Multimodal size distributions obtained with ES-DMA indicated the presence of single Au-NPs (monomer) as well as larger Au-NP clusters such as dimers, trimers, and tetramers under specific solution conditions. The fraction of each aggregate species as a function of time was quantitatively characterized, from which the degree of aggregation, aggregation rate, and stability ratio at different ionic strengths were determined. The latter enabled the extraction of a surface potential (or surface charge density) of 64 +/- 2 mV for 10 nm Au-NPs, which is in good agreement with values obtained from other methods, thus validating our approach. Our results show that ES-DMA is a valuable tool for quantitatively probing the early stages of colloidal aggregation or as a preparatory tool for the size election of aggregates.

Gas-phase ion-mobility characterization of SAM-functionalized Au nanoparticles.

We present results of a systematic examination of functionalized gold nanoparticles (Au-NPs) by electrospray-differential mobility analysis (ES-DMA). Commercially available, citrate-stabilized Au colloid solutions (10-60 nm) were sized using ES-DMA, from which changes in particle size of less than 0.3 nm were readily discerned. It was found that the formation of salt particles and the coating of Au-NPs by salt during the electrospray process can interfere with the mobility analysis, which required the development of sample preparation and data correction protocols to extract correct values for the Au-NP size. Formation of self-assembled monolayers (SAMs) of alkanethiol molecules on the Au-NP surface was detected from a change in particle mobility, which could be modeled to extract the surface packing density of SAMs. A gas-phase temperature-programmed desorption (TPD) kinetic study of SAMs on Au-NPs found the data to be consistent with a second-order Arrhenius-based rate law, yielding an Arrhenius factor of 1.0 x 10 (11) s (-1) and an activation energy approximately 105 kJ/mol. For the size range of SAM-modified Au-NP we considered, the effect of surface curvature on the energetics of binding of carboxylic acid terminated SAMs is evidently negligible, with binding energies determined by TPD agreeing with those reported for the same SAMs on planar surfaces. This study suggests that the ES-DMA can be added to the tool set of characterization methods used to study the structure and properties of coated nanoparticles.

Platelet collagen receptor alpha2beta1 integrin and glycoprotein IIIa Pl(A1/A2) polymorphisms are not associated with nephropathy in type 2 diabetes.

Platelet glycoprotein receptors play a role in the pathogenesis of chronic diabetic complications. Genetic polymorphisms of the alpha2beta1 integrin and glycoprotein IIIa (GPIIIa) have been associated with myocardial infarction, stroke, and diabetic retinopathy. To identify risk factors for their development in a cohort of patients with type 2 diabetes, we evaluated clinical variables and genetic polymorphisms in the alpha2beta1 integrin and GPIIIa genes. Two hundred thirty-four subjects with type 2 diabetes (126 patients with and 108 patients without diabetic nephropathy), as well as 217 nondiabetic healthy subjects, were recruited for this study. Clinical factors for investigation included sex, age at diagnosis, duration of diabetes, body mass index (BMI), and fasting plasma glucose, hemoglobin A(1c) (HbA(1c)), total cholesterol, and triglyceride levels. Genotypes were determined by polymerase chain reaction and restriction fragment length polymorphism analyses. No difference in the Bgl II polymorphism of the alpha2beta1 integrin gene was found between patients with type 2 diabetes with or without nephropathy (11 [8.7%], 47 [37.3%], and 68 patients [54.0%] versus 10 [9.3%], 32 [29.6%], and 66 patients [61.1%] for Bgl II+/+, Bgl II+/-, and Bgl II-/-, respectively; P = 0.271). Multiple logistic regression analyses showed that duration of diabetes, BMI, hypertension, and poor glycemic control were four independent predictors for the development of diabetic nephropathy. No contribution of the Bgl II+ allele of the alpha2beta1 integrin was found for the risk for nephropathy (odds ratio, 1.258; 95% confidence interval, 0.655 to 2.418; P = 0.490). The Pl(A2) allele genotype was not found among our studied subjects. In conclusion, age, duration of diabetes, BMI, and HbA(1c) level are strong predictors for nephropathy in patients with type 2 diabetes. However, the Bgl II polymorphism of the alpha2beta1 integrin gene and the Apa I polymorphism of the platelet GPIIIa gene do not have a major role in the development of diabetic nephropathy in our population.

Pyomyositis in childhood: a case report.

Pyomyositis is a primary infection of skeletal muscle. We report the case of a previously healthy six-year-old who suffered from pyomyositis in the right lower back. He presented with lower back pain and low-grade fever for one week. After a series of laboratory and imaging studies, the diagnosis of right multifidus muscle pyomyositis with abscess formation was made. The patient recovered rapidly after incision and drainage therapy, accompanied by antibiotic treatment. Methicillin-resistant Staphylococcus aureus was cultured from the abscess discharge. It was strongly suspected that herbal medicines and common cold medication the patient had been prescribed before admission to our hospital produced a masking effect that delayed the diagnosis.