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NanoImpact ; 29: 100451, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36626980


MoS2 has been increasingly used in place of graphene as a flexible and multifunctional 2D material in many biomedical applications such as cancer detection and drug delivery, which makes it crucial to evaluate downstream compatibility in human immune cells. Molybdenum is a component of stainless-steel stent implants and has previously been implicated in stent hypersensitivity. In view of this, it is important to ascertain the effect of MoS2 on allergy-relevant cells. Basophils are a less commonly used immune cell type. Unlike mast cells, basophils can be easily derived from primary human blood and can act as a sentinel for allergy. However, merely testing any one type of MoS2 in basophils could result in different biological results. We thus decided to compare 2D MoS2 from the two companies BeDimensional© (BD) and Biograph Solutions (BS), manufactured with two different but commonly exploited methods (BD, deoxycholate surfactant in a high-pressure liquid exfoliation, and BS using glycine in ball-milling exfoliation) to elucidate immunological end-points common to both MoS2 and to demonstrate the need for biological verification for end-users who may require a change of supplier. We report higher histamine production in human basophils with MoS2. No effects on either surface basophil activation markers CD63 and CD203c or reactive oxygen species (ROS) production and cell viability were observed. However, different cytokine production patterns were evidenced. IL-6 and IL-1ß but not TNF and GM-CSF were increased for both MoS2. BS-MoS2 increased IL-4, while BD-MoS2 decreased IL-4 and increased IL-13. Molybdate ion itself only increased IL-1ß and IL-4. Deoxycholate surfactant decreased viability at 18 h and increased ROS upon basophil activation. Therefore, these results demonstrate the safety of MoS2 in human basophils in general and highlight the importance of considering manufacturer additives and variability when selecting and investigating 2D materials such as MoS2.

Basófilos , Hipersensibilidade , Humanos , Molibdênio/metabolismo , Interleucina-4/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Hipersensibilidade/metabolismo , Ácido Desoxicólico/metabolismo
Polymers (Basel) ; 13(9)2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33925187


A simple and scalable fabrication process of graphene nanoplatelets (GnPs)-reinforced polyether ether ketone (PEEK) filaments with enhanced mechanical and thermal performance was successfully demonstrated in this work. The developed PEEK-GnP nanocomposite filaments by a melt-extrusion process showed excellent improvement in storage modulus at 30 °C (61%), and significant enhancement in tensile strength (34%), Young's modulus (25%), and elongation at break (37%) when GnP content of 1.0 wt.% was used for the neat PEEK. Moreover, the GnPs addition to the PEEK enhanced the thermal stability of the polymer matrix. Improvement in mechanical and thermal properties was attributed to the improved dispersion of GnP inside PEEK, which could form a stronger/robust interface through hydrogen bonding and π-π* interactions. The obtained mechanical properties were also correlated to the mechanical reinforcement models of Guth and Halpin-Tsai. The GnP layers could form agglomerates as the GnP content increases (>1 wt.%), which would decline neat PEEK's crystallinity and serve as stress concentration sites inside the composite, leading to a deterioration of the mechanical performance. The results demonstrate that the developed PEEK-GnP nanocomposites can be used in highly demanding engineering sectors like 3D printing of aerospace and automotive parts and structural components of humanoid robots and biomedical devices.

Chemistry ; 26(29): 6715-6725, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32216144


One of the applications of graphene in which its scalable production is of utmost importance is the development of polymer composites. Among the techniques used to produce graphene flakes, the liquid-phase exfoliation (LPE) of graphite stands out due to its versatility and scalability. However, solvents suitable for the LPE process are generally toxic and have a high boiling point, making the processing challenging. The use of low boiling point solvents could be convenient for the processing, due to the easiness of their removal. In this study, the use of poly(methyl methacrylate) (PMMA) as a stabilizing agent is proposed for the production of graphene flakes in a low boiling point solvent, that is, acetone. The graphene dispersions produced in the mixture acetone-PMMA have higher concentration, +175 %, and contain a higher percentage of few-layer graphene flakes (<5 layers), that is, +60 %, compared to the dispersions prepared in acetone. The as-produced graphene dispersions are used to develop graphene/acrylonitrile-butadiene-styrene composites. The mechanical properties of the pristine polymer are improved, that is, +22 % in the Young's modulus, by adding 0.01 wt. % of graphene flakes. Moreover, a decrease of ≈20 % in the oxygen permeability is obtained by using 0.1 wt. % of graphene flakes filler, compared to the unloaded matrix.

ACS Catal ; 10(5): 3313-3325, 2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-33815892


Metallic two-dimensional transition-metal dichalcogenides (TMDs) of the group 5 metals are emerging as catalysts for an efficient hydrogen evolution reaction (HER). The HER activity of the group 5 TMDs originates from the unsaturated chalcogen edges and the highly active surface basal planes, whereas the HER activity of the widely studied group 6 TMDs originates solely from the chalcogen- or metal-unsaturated edges. However, the batch production of such nanomaterials and their scalable processing into high-performance electrocatalysts is still challenging. Herein, we report the liquid-phase exfoliation of the 2H-TaS2 crystals by using 2-propanol to produce single/few-layer (1H/2H) flakes, which are afterward deposited as catalytic films. A thermal treatment-aided texturization of the catalytic films is used to increase their porosity, promoting the ion access to the basal planes of the flakes, as well as the number of catalytic edges of the flakes. The hybridization of the H-TaS2 flakes and H-TaSe2 flakes tunes the Gibbs free energy of the adsorbed atomic hydrogen onto the H-TaS2 basal planes to the optimal thermo-neutral value. In 0.5 M H2SO4, the heterogeneous catalysts exhibit a low overpotential (versus RHE, reversible hydrogen electrode) at the cathodic current of 10 mA cm-2 (η10) of 120 mV and high mass activity of 314 A g-1 at an overpotential of 200 mV. In 1 M KOH, they show a η10 of 230 mV and a mass activity of 220 A g-1 at an overpotential of 300 mV. Our results provide new insight into the usage of the metallic group 5 TMDs for the HER through scalable material preparation and electrode processing.

Small ; 14(26): e1800749, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29845748


Single- and few-layered InSe flakes are produced by the liquid-phase exfoliation of ß-InSe single crystals in 2-propanol, obtaining stable dispersions with a concentration as high as 0.11 g L-1 . Ultracentrifugation is used to tune the morphology, i.e., the lateral size and thickness of the as-produced InSe flakes. It is demonstrated that the obtained InSe flakes have maximum lateral sizes ranging from 30 nm to a few micrometers, and thicknesses ranging from 1 to 20 nm, with a maximum population centered at ≈5 nm, corresponding to 4 Se-In-In-Se quaternary layers. It is also shown that no formation of further InSe-based compounds (such as In2 Se3 ) or oxides occurs during the exfoliation process. The potential of these exfoliated-InSe few-layer flakes as a catalyst for the hydrogen evolution reaction (HER) is tested in hybrid single-walled carbon nanotubes/InSe heterostructures. The dependence of the InSe flakes' morphologies, i.e., surface area and thickness, on the HER performances is highlighted, achieving the best efficiencies with small flakes offering predominant edge effects. The theoretical model unveils the origin of the catalytic efficiency of InSe flakes, and correlates the catalytic activity to the Se vacancies at the edge of the flakes.

Nanotechnology ; 27(41): 415201, 2016 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-27586817


In this article we demonstrate type-II band alignment at the wurtzite/zinc-blende hetero-interface in InAs polytype nanowires using resonance Raman measurements. Nanowires were grown with an optimum ratio of the above mentioned phases, so that in the electronic band alignment of such NWs the effect of the difference in the crystal structure dominates over other perturbing effects (e.g. interfacial strain, confinement of charge carriers and band bending due to space charge). Experimental results are compared with the band alignment obtained from density functional theory calculations. In resonance Raman measurements, the excitation energies in the visible range probe the band alignment formed by the E 1 gap of wurtzite and zinc-blende phases. However, we expect our claim to be valid also for band alignment near the fundamental gap at the heterointerface.