Chiroplasmonic DNA Scaffolded "Fusilli" Structures.

DNA is an ideal template for the design of nanoarchitectures with molecular-like features. Here, we present an optimized assembly strategy for the concatenation of DNA quasi-rings into long scaffolds. Ionic strength, which played a major role during self-assembly, produced the expected high quality only at 15 mM MgCl2. Atomic force microscopy (AFM) characterization showed several micrometer long tubular structures that were used as templates for the positioning of plasmonic nanoparticles (NPs) along a three-dimensional helical path using DNA tethers. As imaged by high-resolution scanning transmission electron microscopy (HR-STEM) and modeled by theoretical calculations, the NPs distributed into a "fusilli" fashion (i.e., a helical pasta shape), displaying chiroptical activity as revealed by a bisignated CD absorption, centered at the plasmon resonance wavelength. The present structures contribute to enrich the ever-developing arena of chiroplasmonic DNA-based nanomaterials and demonstrate that large assemblies are attainable for their future application to develop metamaterials.

Industrial by-products-derived binders for in-situ remediation of high Pb content pyrite ash: Synergistic use of ground granulated blast furnace slag and steel slag to achieve efficient Pb retention and CO2 mitigation.

Ordinary Portland cement (OPC) is a cost-effective and conventional binder that is widely adopted in brownfield site remediation and redevelopment. However, the substantial carbon dioxide emission during OPC production and the concerns about its undesirable retention capacity for potentially toxic elements strain this strategy. To tackle this objective, we herein tailored four alternative binders (calcium aluminate cement, OPC-activated ground-granulated blast-furnace slag (GGBFS), white-steel-slag activated GGBFS, and alkaline-activated GGBFS) for facilitating immobilization of high Pb content pyrite ash, with the perspectives of enhancing Pb retention and mitigating anthropogenic carbon dioxide emissions. The characterizations revealed that the incorporation of white steel slag efficiently benefits the activity of GGBFS, herein facilitating the hydration products (mainly ettringite and calcium silicate hydrates) precipitation and Pb immobilization. Further, we quantified the cradle-to-gate carbon footprint and cost analysis attributed to each binder-Pb contaminants system, finding that the application of these alternative binders could be pivotal in the envisaged carbon-neutral world if the growth of the OPC-free roadmap continues. The findings suggest that the synergistic use of recycled white steel slag and GGBFS can be proposed as a profitable and sustainable OPC-free candidate to facilitate the management of lead-contaminated brownfield sites. The overall results underscore the potential immobilization mechanisms of Pb in multiple OPC-free/substitution binder systems and highlight the urgent need to bridge the zero-emission insights to sustainable in-situ solidification/stabilization technologies.

Highly specific colloidal ɣ-Fe2O3-DNA hybrids: From bioinspired recognition to large-scale lactoferrin purification.

The industry transfer of laboratory-use magnetic separation is still hampered by the lack of suitable nanoparticles, both in terms of their features and large-scale availability. Surface Active Maghemite Nanoparticles (SAMNs) characterized by a unique surface chemistry, low environmental impact, scalable synthesis and functionalization were used to develop a bio-inspired lactoferrin (LF) recognition system. Based on the LF affinity for DNA, a self-assembly process was optimized for obtaining a SAMN@DNA hybrid displaying chemical and colloidal stability and LF specificity. SAMN@DNA was successfully tested for the affinity purification of LF from crude bovine whey. Advantages, such as high selectivity and loading capacity, nanoparticle re-usability, outstanding purity (96 ± 1%), preservation of protein conformation and short operational time, were highlighted. Finally, scalability was demonstrated by an automatic system performing continuous purification of LF from 100 liters day-1 of whey. This study responds to essential prerequisites, such as efficiency, re-usability and industrialization feasibility.

Spermine Oxidase-Substrate Electrostatic Interactions: The Modulation of Enzyme Function by Neighboring Colloidal ɣ-Fe2O3.

Protein-nanoparticle hybridization can ideally lead to novel biological entities characterized by emerging properties that can sensibly differ from those of the parent components. Herein, the effect of ionic strength on the biological functions of recombinant His-tagged spermine oxidase (i.e., SMOX) was studied for the first time. Moreover, SMOX was integrated into colloidal surface active maghemite nanoparticles (SAMNs) via direct self-assembly, leading to a biologically active nano-enzyme (i.e., SAMN@SMOX). The hybrid was subjected to an in-depth chemical-physical characterization, highlighting the fact that the protein structure was perfectly preserved. The catalytic activity of the nanostructured hybrid (SAMN@SMOX) was assessed by extracting the kinetics parameters using spermine as a substrate and compared to the soluble enzyme as a function of ionic strength. The results revealed that the catalytic function was dominated by electrostatic interactions and that they were drastically modified upon hybridization with colloidal ɣ-Fe2O3. The fact that the affinity of SMOX toward spermine was significantly higher for the nanohybrid at low salinity is noteworthy. The present study supports the vision of using protein-nanoparticle conjugation as a means to modulate biological functions.

Integration of DNA-RNA-triplex-based regulation of transcription into molecular logic gates.

In recent years, increasing numbers of noncoding RNA molecules were identified as possible components of endogenous DNA-RNA hybrid triplexes involved in gene regulation. Triplexes are potentially involved in complex molecular signaling networks that, if understood, would allow the engineering of biological computing components. Here, by making use of the enhancing and inhibiting effects of such triplexes, we demonstrate in vitro the construction of triplex-based molecular gates: 'exclusive OR' (XOR), 'exclusive NOT-OR' (XNOR), and a threshold gate, via transcription of a fluorogenic RNA aptamer. Precise modulation was displayed by the biomolecular-integrated systems over a wide interval of transcriptional outputs, ranging from drastic inhibition to significant enhancement. The present contribution represents a first example of molecular gates developed using DNA-RNA triplex nanostructures.

Mechanistic insights into Pb and sulfates retention in ordinary Portland cement and aluminous cement: Assessing the contributions from binders and solid waste.

Identifying immobilization mechanisms of potentially toxic elements (PTEs) is of paramount importance in the field application of solidification/stabilization. Traditionally, demanding and extensive experiments are required to better access the underlying retention mechanisms, which are usually challenging to quantify and clarify precisely. Herein, we present a geochemical model with parametric fitting techniques to reveal the solidification/stabilization of Pb-rich pyrite ash through conventional (ordinary Portland cement) and alternative (calcium aluminate cement) binders. We found that ettringite and calcium silicate hydrates exhibit strong affinities for Pb at alkaline conditions. When the hydration products are unable to stabilize all the soluble Pb in the system, part of the soluble Pb may be immobilized as Pb(OH)2. At acidic and neutral conditions, hematite from pyrite ash and newly-formed ferrihydrite are the main controlling factors of Pb, coupled with anglesite and cerussite precipitation. Thus, this work provides a much-needed complement to this widely-applied solid waste remediation technique for the development of more sustainable mixture formulations.

Acidic Shift of Optimum pH of Bovine Serum Amine Oxidase upon Immobilization onto Nanostructured Ferric Tannates.

Protein-nanoparticle hybrids represent entities characterized by emerging biological properties that can significantly differ from those of the parent components. Herein, bovine serum amine oxidase (i.e., BSAO) was immobilized onto a magnetic nanomaterial constituted of surface active maghemite nanoparticles (i.e., SAMNs, the core), surface-modified with tannic acid (i.e., TA, the shell), to produce a biologically active ternary hybrid (i.e., SAMN@TA@BSAO). In comparison with the native enzyme, the secondary structure of the immobilized BSAO responded to pH variations sensitively, resulting in a shift of its optimum activity from pH 7.2 to 5.0. Conversely, the native enzyme structure was not influenced by pH and its activity was affected at pH 5.0, i.e., in correspondence with the best performances of SAMN@TA@BSAO. Thus, an extensive NMR study was dedicated to the structure-function relationship of native BSAO, confirming that its low activity below pH 6.0 was ascribable to minimal structural modifications not detected by circular dichroism. The generation of cytotoxic products, such as aldehydes and H2O2, by the catalytic activity of SAMN@TA@BSAO on polyamine oxidation is envisaged as smart nanotherapy for tumor cells. The present study supports protein-nanoparticle conjugation as a key for the modulation of biological functions.