Electro-hydrodynamic extraction of DNA from mixtures of DNA and bovine serum albumin.

We report separation of genomic DNA (48 kbp) from bovine serum albumin (BSA) by the electro-hydrodynamic coupling between a pressure-driven flow and a parallel electric field. Electro-hydrodynamic extraction exploits this coupling to trap DNA molecules at the entrance of a microfluidic contraction channel, while allowing proteins and salts to be flushed from the device. Samples (10 µL) containing λ-DNA (1 ng) and BSA (0.3 mg) were injected directly into the device and convected to the contraction channel entrance by a flowing buffer solution. The DNA remains trapped in this region essentially indefinitely, while proteins and salts are eluted. The effectiveness of the concept has been assessed by fluorescence measurements of DNA and BSA concentrations. Electro-hydrodynamic extraction in a single-stage device was found to enhance the concentration of DNA 40-fold, while reducing the BSA concentration by four orders of magnitude. The relative concentrations of DNA to BSA at the contraction channel entrance can be as large as 1.5 : 1, corresponding to an A260/280 ratio of 1.9. The maximum yield of DNA from a salt-free solution is 50%, while salted (150 mM) solutions have a lower yield (38%).

Rapid and Efficient Coacervate Extraction of Cationic Industrial Dyes from Wastewater.

Effluent wastewater containing dyes from textile, paint, and various other industrial wastes have long posed environmental damage. Functional nanomaterials offer new opportunities to treat these effluent wastes in an unprecedentedly rapid and efficient fashion due to their large surface area-to-volume ratio. In this work, we explore a new approach of wastewater treatment using macroionic coacervate complexes formed with zwitterionic polyampholytes and anionic inorganic polyoxometalate (POM) nanoclusters to extract methylene blue (MB) dye as well as other cationic industrial dyes from model wastewater. Biphasic organic-inorganic macroion complexes are designed to produce a small volume of coacervate adsorbents of high density and viscoelasticity, in contrast to a large volume of supernatant solution for rapid and efficient dye removal. The efficiency of coacervate extraction is characterized by the adsorption isotherm and maximum MB uptake capacity against the concentrations of polyampholyte, POM, and LiCl salt using UV-vis spectrophotometry to optimize the coacervate formation conditions. Our macroionic coacervate complexes could reach nearly 99% removal efficiency for the model wastewater samples of varied MB concentration in <1 min. The extraction capacity up to ∼400 mg/g far surpasses the dye extraction efficiency of widely used activated carbon adsorbents. We also explore the regeneration of coacervate complexes containing high concentration of extracted MB by a simple Fenton oxidation process to bleach coacervate complexes for repeated POM usage, which shows similar MB extraction efficiency after regeneration. Hence, coacervate extraction based upon spontaneous liquid-liquid separating complexation between polyzwitterions and POMs is demonstrated as a rapid, efficient, and sustainable method for industrial dye wastewater treatment. In perspective, coacervate extraction could advantageously possess dual processing options in separation industry through either membrane fabrication or use directly in mixer-settlers.

Non-cognitive factors predicting success in orthopedic surgery residency.

Admissions to orthopedic surgery is a highly competitive process. Traditionally measures such as United States Medical Licensing Examination (USMLE) Step 1, class rank, AOA status have been major determinants in the ranking process. However, these traditional objective measures show mixed correlation to clinical success in orthopedic surgery residency. There have been several studies on the cognitive factors and their correlation with success in residency. However, it is clear that residency requires more than objective cognition, emphasizing complex social interactions that are influenced by non-cognitive variables including personality, work ethic, etc. This review aims to summarize the current understanding of non-cognitive factors influencing performance in orthopaedic surgical residency.

Selective ion exchange governed by the Irving-Williams series in K2Zn3[Fe(CN)6]2 nanoparticles: toward a designer prodrug for Wilson's disease.

The principle of the Irving-Williams series is applied to the design of a novel prodrug based on K2Zn3[Fe(CN)6]2 nanoparticles (ZnPB NPs) for Wilson's disease (WD), a rare but fatal genetic disorder characterized by the accumulation of excess copper in the liver and other vital organs. The predetermined ion-exchange reaction rather than chelation between ZnPB NPs and copper ions leads to high selectivity of such NPs for copper in the presence of the other endogenous metal ions. Furthermore, ZnPB NPs are highly water-dispersible and noncytotoxic and can be readily internalized by cells to target intracellular copper ions for selective copper detoxification, suggesting their potential application as a new-generation treatment for WD.

Gallium analogue of soluble Prussian blue KGa[Fe(CN)6]·nH2O: synthesis, characterization, and potential biomedical applications.

The gallium analogue of the soluble Prussian blue with the formula KGa[Fe(CN)6]·nH2O is synthesized and structurally characterized. A simple aqueous synthetic procedure for preparing nanoparticles of this novel coordination polymer is reported. The stability, in vitro ion exchange with ferrous ions, cytotoxicity, and cellular uptake of such nanoparticles coated with poly(vinylpyrrolidone) are investigated for potential applications of delivering Ga(3+) ions into cells or removing iron from cells.