No abstract

Urinary tract infection (UTI), which can be caused by various pathogens, if not detected at an early stage can be fatal. It is essential to identify the specific pathogen responsible for UTI for appropriate treatment. This study describes a generic approach to the fabrication of a prototype for the noninvasive detection of a specific pathogen using a tailor-made plasmonic aptamer-gold nanoparticle (AuNP) assay. The assay is advantageous because the adsorbed specific aptamers passivate the nanoparticle surfaces and reduce and/or eliminate false-positive responses to nontarget analytes. Based on the localized surface plasmon resonance (LSPR) phenomena of AuNP, a point-of-care aptasensor was designed that shows specific changes in the absorbance in the visible spectra in the presence of a target pathogen for robust and fast screening of UTI samples. In this study, we demonstrate the specific detection of Klebsiella pneumoniae bacteria with LoD as low as 3.4 × 10 3 CFU/mL.

It is hypothesized that nonlinear solid friction between the gel matrix and DNA molecules inhibits the motion of DNA through the nanopores of the gel during electrophoresis. In this article, it is demonstrated that external noise can alleviate the effect of solid friction, thus enhancing the mobility of DNA in an electrophoretic setting. In the presence of noise, the mobility of DNA increases by more than ∼113% compared to conventional electrophoresis. Although at a high power of noise, DNA exhibits Arrhenius kinetics, at a low power of noise, super-Arrhenius kinetics suggests the collective behavior of the activated motion of DNA molecules. A stochastic simulation following modified Langevin dynamics with the asymmetric pore size distribution of the agarose gel successfully predicts the mobility of DNA molecules and reveals the salient features of the overall dynamics. This "noise lubricity" may have a broader applicability from molecular to macroscopic locomotion.

Dynamic contact line lithography (DCLL) is generally used for the templateless but well-ordered deposition of polymer micro/nanostructures from the solution of homopolymer. DCLL from the blend of several polymers in a common suitable solvent can generate rich morphologies including nanostructured Janus micro threads on a surface which might be challenging to fabricate using any other method. A blend of polystyrene (PS) and poly(methyl methacrylate) (PMMA) in toluene with different compositions and concentrations are used for DCLL at a constant contact line speed of 10 μm/s. Variations of compositions and the overall concentration of polymer, engender Janus micro threads to undulated threads and multi-layered micro/nanodroplets of PS/PMMA. Interestingly, the more soluble PS phase separates first compared to less soluble PMMA near the contact line due to the enhanced local concentration of PS during the convective flow of the solvent toward the contact line. This is also verified by DCLL using PS/PMMA blend in ethyl acetate as well. In that case, more soluble PMMA deposits first near the contact line compared to marginally less soluble PS in the solvent.