Real-Time Observation of Superstructure-Dependent DNA Origami Digestion by DNase I Using High-Speed Atomic Force Microscopy

DNA nanostructures have emerged as intriguing tools for numerous biomedical applications. However, in many of those applications and most notably in drug delivery, their stability and function may be compromised by the biological media. A particularly important issue for medical applications is their interaction with proteins such as endonucleases, which may degrade the well-defined nanoscale shapes. Herein, fundamental insights into this interaction are provided by monitoring DNase I digestion of four structurally distinct DNA origami nanostructures (DONs) in real time and at a single-structure level by using high-speed atomic force microscopy. The effect of the solid–liquid interface on DON digestion is also assessed by comparison with experiments in bulk solution. It is shown that DON digestion is strongly dependent on its superstructure and flexibility and on the local topology of the individual structure.     

The h-index as an almost-exact function of some basic statistics

Scientometrics - As is known, the h-index, h, is an exact function of the citation pattern. At the same time, and more generally, it is recognized that h is “loosely” related to the...     

A new approach for the preparation of hydrophilic poly(L‐lactide) porous scaffold for tissue engineering by using lamellar single crystals

The aim of the present work was to study the possibility of building a porous scaffold for tissue engineering with a new bottom‐up approach, obtained by assembling two‐dimensional‐micro, one‐dimensional‐nano sized poly(L ‐lactide) lamellar single crystals. This choice was dictated by the fact that polymer single crystals have structural and morphological features which can be exploited for chemical surface modifications to give a system characterized by a high specific active surface area. Indeed, the outermost amorphous regions can undergo functionalization reactions easily, whereas the inner, relatively inaccessible and inert crystalline core ensures morphological and mechanical stability. The assembling method employed to give the porous structures is based on a mould pressing, salt leaching technique and was found to be facile and versatile. In the first part of this paper we report the experimental results obtained to find the best conditions to achieve a suitable frame in terms of morphology, porosity and mechanical properties. In the second part of the paper, we describe the biological tests performed by using mouse fibroblasts seeded onto scaffolds prepared from pristine and surface hydrolysed lamellae. The results show that the samples obtained are suitable for sustaining cells which can proliferate and reach the inner pores of the scaffold containing hydrolysed single crystals much better than those prepared from pristine lamellae. Copyright © 2012 Society of Chemical Industry     

Response of mice connective tissue to three different endodontic materials

The aim of this study was to evaluate the biocompatibility of mineral trioxide aggregate (MTA) Bio and Portland cement (PC) and compare with those of ProRoot MTA. Polyethylene tubes were filled with materials and placed into dorsal subcutaneous connective tissue of Wistar albino rats. After 7, 30, and 60 days after the surgical procedure, the implants with the surrounding tissue were removed. Tissue samples were subjected to histological processing, and sections were stained with hematoxylin and eosin. Sections were evaluated for the intensity of inflammation, predominant cell type, presence of fibrous capsule and granulation tissue. Data were submitted to Kruskal‐Wallis test at a significant level of P ≤ 0.05. No statistical differences were observed at any evaluated condition among tested materials (P > 0.05). Statistically significant differences were observed between mean inflammatory scores, cell types and granulation tissue of the same material in different experimental periods (P < 0.05). Can be concluded that biocompatibility of MTA bio and PC were comparable with that of ProRoot MTA. Microsc. Res. Tech. 76:311–315, 2013. © 2013 Wiley Periodicals, Inc.     

Influence of the drying route on the depolymerization and properties of chitosan

In this work, a chitosan sample with a high degree of deacetylation (DD >95%) obtained from freshwater shrimp shells was subjected to drying processes in an electric oven and by supercritical CO₂. The results indicated that drying chitosan particles with supercritical CO₂ resulted in a very significant increase in specific surface area and pore volume, and also increased the material's crystallinity index. This drying route led to a more than 10‐fold reduction in viscosimetric molecular weight (from 35.3 to 3.0 kDa), indicating that the physical drying process caused the chitosan to depolymerize, which usually occurs by enzymatic and chemical methods, according to the literature. Low molecular weight chitosan is essential for some applications in the field of biomedicine (drug delivery for example); hence, drying via the CO₂ route can be considered a promising technique for the production of high value‐added materials with applications in this area. POLYM. ENG. SCI., 55:1969–1976, 2015. © 2014 Society of Plastics Engineers     

Electrochemical behavior of hydrophobic silane–zeolite coatings for corrosion protection of aluminum substrate

The anticorrosive properties of a silane–zeolite composite coating applied on a 6061 aluminum substrate was investigated. The composite film, deposited by dip-coating technique, was prepared with different contents of SAPO34 powder (60–90 wt%) with the purpose of evaluating the protective action offered by the zeolite-filled silane matrix. Corrosion protection performance, during immersion in 3.5% NaCl solution, was evaluated by means of a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). The coating evidenced good barrier properties and high hydrophobicity. The addition of zeolite in the silane matrix induced, as expected, a reduction of cathodic and anodic current. The zeolite improved the barrier properties of the hybrid sol–gel films, enhancing the resistance to localized corrosion attacks. Better results were observed for the sample with 80 wt% of zeolite filler that evidenced still acceptable protective action after 3 days of immersion in the sodium chloride solution.