No abstract

A B S T R A C TFormation of bacterial biofilm on indwelling urinary catheters usually causes catheter-associated urinary tract infections (CAUTIs) that represent high percent of nosocomial infections worldwide. Therefore, coating urinary catheter with antibacterial and antifouling coating using facile technique is in great demand. In this study, commercial urinary catheter was coated with a layer of the self-polymerized polydopamine which acts as active platform for the in situ formation of silver nanoparticle (AgNPs) on catheter surface. The formed coating was intensively characterized using spectroscopic and microscopic techniques. The coated catheter has the potential to release silver ion in a sustained manner with a concentration of about 2-4 μg ml À1 . Disk diffusion test and colony forming unites assay verified the significant bactericidal potential of the AgNPs coated catheter against both gram-positive and gram-negative bacteria as a consequence of silver ion release. In contrast to commercial catheter, the AgNPs coated catheter prevented the adherence of bacterial cells and biofilm formation on their surfaces. Interestingly, scanning electron microscope investigations showed that AgNPs coated catheter possess greater antifouling potential against gram-positive bacteria than against gram-negative bacteria. Overall, the remarkable antibacterial and antifouling potential of the coated catheter supported the use of such facile approach for coating of different medical devices for the prevention of nosocomial infections.

Hydroxyapatite nanoparticles (nHA) have been used in different biomedical applications where certain particle size distribution and morphology are required. Chitosan/hydroxyapatite (CS/HA) nanocomposites were prepared using in situ coprecipitation technique and the effect of the reaction temperature on the crystallization and particle growth of the prepared nanohydroxyapatite particles was investigated. The composites were prepared at different synthesis temperatures (−10, 37, and 60°C). XRD, FTIR, thermal analysis, TEM and SEM techniques were used to characterize the prepared specimens. It was found that the increase in processing temperature had a great affect on particle size and crystal structure of nHA. The low temperature (−10°C) showed inhabitation of the HA growth in c-direction and low crystallinity which was confirmed using XRD and electron diffraction pattern of TEM. Molar ratio of the bone-like apatite layer (Ca/P) for the nanocomposite prepared at 60°C was higher was higher than the composites prepared at lower temperatures (37 and −10°C).

The electrical conductivity of polymer complexes of bis-2,6-diaminopyridinesulphoxide with CuCl2, CuBr2 and CuI2 was measured at different frequencies and temperatures. It was found that the conductivity increases as frequency and/or temperature increases. The dielectric constant, dielectric loss and relaxation time of the polymer complexes were calculated.

In this work, MWCNT-COOH-cellulose nanocomposite was prepared with MWCNT-COOH, SOCl2 as leaving group and cellulose as an adsorbent (A1); MgO nanoparticles have been successfully coated on the surface of nanocomposite by directly adding to A1 (MWCNT-COOH-cellulose-MgO; A2), magnesium nitrate was added to A1 and MgO nanoparticles were achieved by coating indirectly on the surfaces (MWCNT-COOH-cellulose-MgO; A3). These nanocomposites (A1, A2, and A3) were used for the removal of methyleneblue (MB) dye from aqueous solution. For characterization of adsorbent surfaces, the FT-IR, TEM, SEM, and XRD analysis were used. The effects of initial concentration of MB dye, contact time, and temperature on the adsorption were studied. According to the results, 55 min was selected as the optimum contact time for the removal process. The equilibrium data of adsorption were well fitted and the Langmuir (type III) model had the best agreement because it possesses high value of linear regression, high value R 2 , and least value of average relative error, ARE (%). Parameters of thermodynamics including enthalpy (∆H°), entropy (∆S°), and Gibbs energy (∆G°) were calculated. Kinetic data had best agreement with pseudo-second-order model. Graphical abstract Schematic synthesis of MWCNT-COOH-cellulose-MgO NP nanocomposite as adsorbent

No abstract

No abstract

We describe new method for preparing DNA nanospheres for a self-assembled atenolol@DNA (core/shell) drug delivery system. In this paper, we propose the electrochemical transformation of an alkaline polyelectrolyte solution of DNA into DNA nanospheres. We successfully electrosynthesized DNA nanospheres that were stable for at least 2 months at 4 °C. UV–visible spectra of the prepared nanospheres revealed a peak ranging from 372 to 392 nm depending on the DNA concentration and from 361 to 398.3 nm depending on the electrospherization time. This result, confirmed with size distribution curves worked out from transmission electron microscopy (TEM) images, showed that increasing electrospherization time (6, 12 and 24 h) induces an increase in the average size of DNA nanospheres (48, 65.5 and 117 nm, respectively). In addition, the average size of DNA nanospheres becomes larger (37.8, 48 and 76.5 nm) with increasing DNA concentration (0.05, 0.1 and 0.2 wt%, respectively). Also, the affinity of DNA chains for the surrounding solvent molecules changed from favorable to bad with concomitant extreme reduction in the zeta potential from −31 mV to −17 mV. Principally, the attractive and hydrophobic interactions tend to compact the DNA chain into a globule, as confirmed by Fourier transform infrared spectroscopy (FTIR) and TEM. To advance possible applications, we successfully electro self-assembled an atenolol@DNA drug delivery system. Our findings showed that electrospherization as a cost–benefit technique could be effectively employed for sustained drug release. This delivery system achieved a high entrapment efficiency of 68.03 ± 2.7% and a moderate drug-loading efficiency of 3.73%. The FTIR spectra verified the absence of any chemical interaction between the drug and the DNA during the electrospherization process. X-ray diffraction analysis indicated noteworthy lessening in atenolol crystallinity. The present findings could aid the effectiveness of electrospherized DNA for use in various other pharmaceutical and biomedical applications.