Attractive Intrinsic Properties Research Articles

Nanostructured Iridium Oxide: State of the Art

Iridium Oxide (IrO2) is a metal oxide with a rutile crystalline structure, analogous to the TiO2 rutile polymorph. Unlike other oxides of transition metals, IrO2 shows a metallic type conductivity and displays a low surface work function. IrO2 is also characterized by a high chemical stability. These highly desirable properties make IrO2 a rightful candidate for specific applications. Furthermore, IrO2 can be synthesized in the form of a wide variety of nanostructures ranging from nanopowder, nanosheets, nanotubes, nanorods, nanowires, and nanoporous thin films. IrO2 nanostructuration, which allows its attractive intrinsic properties to be enhanced, can therefore be exploited according to the pursued application. Indeed, IrO2 nanostructures have shown utility in fields that span from electrocatalysis, electrochromic devices, sensors, fuel cell and supercapacitors. After a brief description of the IrO2 structure and properties, the present review will describe the main employed synthetic methodologies that are followed to prepare selectively the various types of nanostructures, highlighting in each case the advantages brought by the nanostructuration illustrating their performances and applications.

Osmundea sp. macroalgal polysaccharide-based nanoparticles produced by flash nanocomplexation technique

The macroalgae-derived polysaccharides' biological potential has been explored due to their attractive intrinsic properties such as biocompatibility, biodegradability, and their ability to conjugate with other compounds. In particular, in the drug delivery systems field, the anionic macroalgae polysaccharides have been combined with cationic compounds through ionotropic gelation and/or bulk mixing. However, these techniques did not assure reproducibility, and the stability of nanoparticles is undesired. To overcome these limitations, herein, the polysaccharide extracted from Osmundea sp. was used to produce nanoparticles through the flash nanocomplexation technique. This approach rapidly mixed the negative charge of macroalgae polysaccharide with a positive chitosan charge on a millisecond timescale. Further, diclofenac (an anti-inflammatory drug) was also incorporated into complex nanoparticles.Overall, the gathered data showed that hydrodynamic diameter nanoparticles values lower than 100 nm, presenting a narrow size distribution and stability. Also, the diclofenac exhibited a targeted and sustained release profile in simulating inflammatory conditions. Likewise, the nanoparticles showed excellent biological properties, evidencing their suitability to be used to treat inflammatory skin diseases.

Toward Spinning Greener Advanced Silk Fibers by Feeding Silkworms with Nanomaterials

Silk has been used in several biomedical applications, including tissue engineering, drug delivery systems, biomedical implants, and diagnostic medical devices, due to its attractive intrinsic properties such as biocompatibility, controllable biodegradability, and excellent mechanical properties. In recent years, several attempts have been made to produce silk fibers with improved properties and new functionalities by feeding silkworms with modified diets containing nanomaterials. Nanomaterials possess unique physical, chemical, and biological properties and when combined with silk can expand its applicability for biomedical applications. Feeding silkworms with modified diets containing nanomaterials is a greener method of producing functionalized silk fibers when compared to the alternative postfunctionalization methods that include multistep procedures and toxic chemicals. The main advantages of using this greener method are related to the reduced usage of resources such as water, energy, and additional chemicals to spin functional silk fibers, the maintenance of intrinsic silk properties, the stability of the added new functionalities, and the possibility of large-scale production. Feeding silkworms with different nanomaterials such as carbon-based nanomaterials, metal and metal oxide nanoparticles, and quantum dots has led to the production of silk fibers with improved properties (e.g., mechanical and thermal) and/or new functionalities (e.g., magnetical and luminescence). However, nanomaterials concentration, dimensions, and solubility were shown to influence their uptake by silkworms as well as silk fiber properties. Here, we review the literature that focuses on the feeding of silkworms with nanomaterials, highlighting the acquired new functionalities and improved properties of the obtained greener and more sustainable silk fibers.

Combating Proteins with Proteins: Engineering Cell-Penetrating Peptide Antagonists of Amyloid-β Aggregation and Associated Neurotoxicity.

A central event that underlies the etiology of Alzheimer's disease (AD) is the self-assembly of the amyloid-β (Aβ) peptide into aggregates termed amyloids. Increasing evidence implicates soluble prefibrillar Aβ oligomers in the neurodegeneration and synaptic dysfunction in AD. Recently we introduced a new class of highly promising antagonists of Aβ amyloidogenesis: designed cell-penetrating peptides (CPPs). These CPPs combine the attractive intrinsic properties of peptides (high target specificity and selectivity, biocompatibility, biodegradability, and ease and low cost of production) with potent therapeutic effects (inhibition of Aβ oligomerization, fiber formation, and neurotoxicity) and highly efficient delivery (to target cells and subcellular organelles).

Theoretically obtained insight into the mechanism and dioxetanone species responsible for the singlet chemiexcitation of Coelenterazine

Coelenterazine is a widespread bioluminescent substrate for a diverse set of marine species. Moreover, its imidazopyrazinone core is present in eight phyla of bioluminescent organisms. Given their very attractive intrinsic properties, these bioluminescent systems have been used in bioimaging, photodynamic therapy of cancer, as gene reporter and in sensing applications, among others. While it is known that bioluminescence results from the thermolysis of high-energy dioxetanones, the mechanism and dioxetanone species responsible for the singlet chemiexcitation of Coelenterazine are not fully understood. The theoretical characterization of the reactions of model Coelenterazine dioxetanones showed that efficient chemiexcitation is caused by a neutral dioxetanone with limited electron and charge transfer, by accessing a region of the PES where ground and excited states are nearly-degenerated. This finding was supported by calculation of equilibrium constants, which showed that only neutral dioxetanone is present in conditions associated with bioluminescence. Moreover, while cationic amino-acids easily protonate amide dioxetanone, anionic ones cannot deprotonate the neutral species. These results indicate that, contrary to existent theories, efficient chemiexcitation can occur with significant electron and/or charge transfer. In fact, these processes can be prejudicial to chemiexcitation, as anionic dioxetanones showed a less efficient chemiexcitation despite the occurrence of significant electron and charge transfer.

Direct laser scribed graphene/PVDF-HFP composite electrodes with improved mechanical water wear and their electrochemistry

As a recent addition to carbon nanomaterials, graphene has been widely investigated in sensing and energy applications due of its specific two-dimensional nanostructure and attractive intrinsic properties. Laser scribing of graphite oxide (GO) is a facile and cost-effective technology for fabricating patterned reduced graphene oxide electronics in a single-step. However, if the laser scribing does not occur through all of the layers of the graphite oxide, the existence of water-soluble graphite oxide underneath the laser scribed graphene (LSG) may result in an unexpected low-stability of the produced electronic elements in aqueous media. This study investigates the electrochemical performance and mechanical stability of LSG films that contained various amounts of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as a binder, blended into the GO dispersion. The laser scribed composite graphene electrodes not only showed improved water mechanical wear resistance, but were largely unaffected in terms of electrochemical behaviour when compared with the binder-free LSG. The findings are significant in terms of the development of robust bioelectronics, to be employed in aqueous environments, based on the simple methodology of laser scribing of GO.

Innovative Solutions for the Nanoscale Packaging of Silicon-Based and Biological Nanowires: Development of a Generic Characterization and Integration Platform

With their attractive intrinsic properties, such as morphology, autoassembling properties, and tailorability, nano-objects could provide alternative and innovative routes to current microelectronics and nanoelectronics. Further insight on their electrical properties, especially in terms of statistics and reproducibility, as well as on their potential integration into silicon-based electronics is, however, often required to be able to fully exploit their potential. This paper proposes an innovative approach using a generic structure allowing the study of nano-objects electrical properties. Regarding the nano-objects integration, a homogeneous approach is presented with the in situ fabrication of atomic wires as a possible planar interconnection system. A heterogeneous approach is described as well with the characterization and preliminary integration of biological material, such as deoxyribonucleic acid-based nanowires or amyloid fibers.

Long-term stability of hydrogen nanobubble fuel

Hydrogen has many attractive intrinsic properties that can be used for improving engine efficiency and emission performance. In this paper, the presence and long term stability of hydrogen nanobubbles (HNBs) in gasoline fuel were investigated. A HNB–gasoline blend is fabricated by nanobubble generator which consists of gas–liquid dispersion system. After the generation of HNBs in gasoline, the presence and long-term stability of HNB in HNB–gasoline blend were experimentally examined by using the nanoparticle tracking analysis (NTA) method. The particle analysis was performed for 121 d at a constant temperature of 298.15 K. The results show that the mean diameter and concentration of HNB are 159.00 ± 31.91 nm and 11.25 ± 2.77 × 108 particles/ml, respectively, just after HNB generation in gasoline fuel. After 121 d of observation, there were no remarkable change in the mean diameter and concentration of HNB. From the results of gas chromatography/mass spectrometry (GC/MS) measurement, it is possible that some compounds in HNB–gasoline blend obtain functional group by replacement reaction and non-main component decreases. Furthermore, the ζ-potential of HNB–gasoline blend after 121 d was about −30 mV, indicating the existence and stability of HNBs in gasoline fuel for a long time.

Antimicrobial peptides: review of their application in musculoskeletal infections

Antimicrobial resistance is expected to increase the burden of osteomyelitis drastically. The rise in resistant bacterial strains is driving researchers to find new treatment options. As a potential new antibiotic class, antimicrobial peptides (AMPs) combine several attractive intrinsic properties. Their minimal propensity for inducing antimicrobial resistance could be of particular clinical significance. AMPs act as an essential part of the innate immune system and have been identified in virtually all forms of life. These short, positively charged peptides have a combined pore-forming and intracellular killing effect on a broad range of microorganisms. Their reported spectrum of action includes resistant bacterial strains, viruses, and fungi. Moreover, immunomodulating, antitumoric, and angiogenic mechanisms have been reported. We have designed degradable and nondegradable drug-release systems for local treatment with AMPs. In animal models of osteomyelitis, these systems reduced bone infection caused by both resistant and nonresistant strains. The systemic application of several peptides for experimental detection and treatment of bone and soft-tissue infection is also discussed in this review. Radioactive-labeled peptides have accurately discriminated sterile inflammation from active infection in imaging studies. Successful preclinical studies of AMPs indicate that clinical evaluation of these powerful antibiotic agents is in order.

A novel approach to hydrolyzable polyvinylketal from poly(vinyl alcohol) and acetone under phase transfer catalyst conditions

Ketalization reaction of poly(vinyl alcohol) (PVA) by acetone under acidic-catalyst/phase-transfer-catalyst was carried out easily and the structure of the product both swelled and dissolved in dimethyl sulfoxide-d 6 (DMSO-d 6) was confirmed, which then indicated the structural change in the product polyvinylketal (PVKT) due to its hydrolysis in water, by NMR measurements. The effect of catalysts on reaction was probed from experimental viewpoint, compared with the theoretical calculation applicable to the previous classical method. It was observed that high ketalization degree PVKT was obtained with the presence of water and the effect of water on reaction was also probed in the present method, which may result in further application in the total syntheses of complex macromolecules from polyols and ketones. The behavior of PVKT in water under different conditions, which is very similar to that described in previous report, was also studied, as well as the specific viscosity ( η sp) of PVKT solution, and proper explanation is proposed. And the present study may lead to a further investigate of attractive intrinsic properties of PVKT.