Centrum pre nanodiagnostiku materiálov

KÁLOSI, Anna – LABUDOVÁ, Martina – ANNUŠOVÁ, Adriana – BENKOVIČOVÁ, Monika – BODÍK, Michal – KOLLÁR, Jozef – KOTLÁR, Mário – KASAK, Peter – JERGEL, Matej – PASTOREKOVÁ, Sylvia – ŠIFFALOVIČ, Peter – MAJKOVÁ, Eva

In Biomaterials Science. Vol. 8, iss. 7 (2020)

https://doi.org/10.1039/C9BM01975H

Abstract

We evaluate the application of surfactant-free liquid-phase exfoliated MoS₂ nanosheets as a nanoplatform for a cancer detection and treatment system equipped with an antibody–antigen based recognition element. Employing antigen–antibody binding, we increased the probability of the endocytosis of MoS₂ nanosheets into CAIX expressing cells by 30%. The nanosheets are functionalized with a specific antibody M75, which forms an antigen–antibody complex with CAIX. The bioconjugation of MoS₂ nanosheets involves biocompatible components with low cytotoxicity, verified in the tested cell lines by fluorescence-based cell viability assay. The cellular internalization is quantified by flow cytometry, while the internalization is confirmed by label-free confocal Raman imaging. Raman measurements show increased lysosomal activity in the proximity of the internalized nanoplatforms.

SUBAIR, Riyas – GIROLAMOC,  Diego Di – BODIK, Michal – NÁDAŽDY, Vojtech – LI, Bo – NÁDAŽDY, Peter – MARKOVIČ, Zoran – BENKOVIČOVÁ, Monika – CHLPÍK, Juraj – KOTLÁR, Mário – HALAHOVETS, Yurily – ŠIFFALOVIČ, Peter – JERGEL, Matej – TIANE, Jianjun – BRUNETTI, Francesca – MAJKOVÁ, Eva

In Solar Energy. Vol. 189, (2019)

https://doi.org/10.1016/j.solener.2019.07.088

Abstract

The doping effect of carbon nanodots (CNDs) in the PC₆₁BM electron-transport layer on the performance of inverted planar MAPbI₃ perovskite solar cells (PSCs) having two different kinds of the hole-transport layer, namely organic PEDOT:PSS and inorganic NiO_x, was investigated. The CH₃NH₃PbI₃ perovskite layer was deposited in air at 35% humidity. An average 11% and 12% enhancement of the power conversion efficiency (PCE) was achieved for 1 wt% CNDs doping in the PSCs with PEDOT:PSS and NiO_x, respectively. This improvement is attributed to high electron density of CNDs resulting in a triple increase of the electrical conductivity of the PC₆₁BM layer and passivation of the perovskite/PC₆₁BM interface that is reflected by an increase of the open-circuit voltage. In line with this, parallel resistance and fill factor of the PSCs are also improved. Moreover, the energy-resolved electrochemical impedance spectroscopy revealed additional free-charge carriers in the PC₆₁BM layer generated under illumination that were detected via the polaron states formation in the band gap with positive effect on the short-circuit current. All these factors contribute to the PCE improvement. Stability tests of the PSC with PEDOT:PSS under a continuous 24 hour 1.5 AM illumination showed a five times smaller final PCE decrease for the 1 wt% CNDs doping of the PC₆₁BM layer comparing to the undoped counterpart. The passivation effect of CNDs, namely electron filling the traps formed by the photo-dimerization and photo-oxidation of PC₆₁BM molecules, is responsible for this remarkable improvement of the short-term stability.

KALOSI, Anna – DEMYDENKO, Maksym – BODÍK, Michal – HAGARA, Jakub – KOTLÁR, Mário – KOSTIUK, Dmytro – HALAHOVETS, Yurily – VÉGSÖ, Karol – ROLDAN, Alicia Marin – MAURYA, Gulab Singh – ANGUŠ, Michal – VEIS, Pavel – JERGEL, Matej – MAJKOVÁ, Eva – ŠIFFALOVIČ, Peter

In Langmuir. Vol. 35, iss. 30 (2019)

https://doi.org/10.1021/acs.langmuir.9b01000

Abstract

Few-layer MoS₂ films stay at the forefront of current research of two-dimensional materials. At present, continuous MoS₂ films are prepared by chemical vapor deposition (CVD) techniques. Herein, we present a cost-effective fabrication of the large-area spatially uniform films of few-layer MoS₂ flakes using a modified Langmuir–Schaefer technique. The compression of the liquid-phase exfoliated MoS₂ flakes on the water subphase was used to form a continuous layer, which was subsequently transferred onto a submerged substrate by removing the subphase. After vacuum annealing, the electrical sheet resistance dropped to a level of 10 kΩ/sq, being highly competitive with that of CVD-deposited MoS₂ nanosheet films. In addition, a consistent fabrication protocol of the large-area conductive MoS₂ films was established. The morphology and electrical properties predetermine these films to advanced detecting, sensing, and catalytic applications. A large number of experimental techniques were used to characterize the exfoliated few-layer MoS₂ flakes and to elucidate the formation of the few-layer MoS₂ Langmuir film.

BENKOVIČOVÁ, Monika – HOLOS, Ana – NÁDAŽDY, Peter – HALAHOVETS, Yurily – KOTLÁR, Mário – KOLLÁR, Jozef – ŠIFFALOVIČ, Peter – JERGEL, Matej – MAJKOVÁ, Eva – MOSNÁČEK, Jaroslav – IVANČO, Ján

In Physical Chemistry Chemical Physics. Vol. 21, iss. 18 (2019)

Abstract

The ability to control the interparticle distance in self-assembled arrays of nanoparticles plays an important role in a large number of applications, which require tunable electronic and photonic properties. Importantly, practical applications in real devices rely on arrays satisfying more stringent requirements of lateral homogeneity controlled over a large scale. Herein, the interparticle distance in ordered nanoparticle assemblies was controlled by varying the nanoparticle effective size via the molecular chemical nature and chain length of the ligand. Iron oxide nanoparticles (IONPs) were functionalized by three types of ligands, namely (i) a mixture of oleic acid/oleylamine (OA/OAm), (ii) poly(n-butyl acrylate) (PBA) and (iii) polystyrene (PS), while two different molar masses of PBA and PS were used. The polymeric ligands with narrow dispersity and bearing phosphonic chain-end groups were prepared by atom transfer radical polymerization. Functionalization of the IONPs with polymeric ligands was achieved using a ligand exchange method. Both the hydrodynamic diameter and size distribution of the nanoparticles in colloidal solution were determined by dynamic light scattering (DLS). The mean interparticle distances in Langmuir–Schaefer monolayers prepared on solid substrates were assessed by means of the pair correlation function calculated from the atomic force microscopy (AFM) images. Furthermore, the lateral ordering, homogeneity, and interparticle distances averaged over a mesoscopic scale of the ordered monolayers were studied by the grazing-incidence small-angle X-ray scattering (GISAXS) technique. We demonstrate that the (nanoparticle) centre-to-centre distance in the ordered assemblies constituted by the IONPs with the core diameter of about 6 nm can be varied from 7.6 to about 12 nm with the resulting interparticle gap change by a factor of about 4.

 ZÁPRAŽNÝ, Zdenko – KORYTÁR, Dušan – JERGEL, Matej – HALAHOVETS, Yurily – KOTLÁR, Mário – MATKO, Igor – HAGARA, Jakub – ŠIFFALOVIČ, Peter – KECKES, Jozef – MAJKOVÁ, Eva

In International Journal of Advanced Manufacturing Technology. Vol. 102, iss. 9-12 (2019)

https://doi.org/10.1007/s00170-019-03392-z

Abstract

Micro-Raman spectroscopy, scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) were used to study the effect of cutting speed and cutting depth on the mode of the single-point diamond fly cutting of Ge(110) surface via crystallinity of the chips. Reducing the cutting depth from 15 to 2 μm and concurrently cutting speed from 10 to 2 mm/min at 2000 rpm, the content of amorphous phase in the chips increased at the expense of the crystalline one from 28 to 46%. Simultaneously, the chip morphology visible by SEM suggested transition from a brittle to a mixed brittle-ductile mode of nanomachining. The damage transition line indicates 1/3 portion of the ductile component at 2-μm cutting depth that produced twisted lamellae of a width of 18–20 μm without any signs of a fracture. As the feed rate here was 1 μm/rev, the tool made 18–20 revolutions while passing the same point of the nanomachined surface that was enough to gradually remove the surface region damaged by the brittle cutting component along with the entire amorphous region beneath, both being delaminated by the chips. This explains the dislocation-free single-crystal lattice beneath the Ge(110) surface machined under these conditions. A close relationship between the brittle mode of nanomachining and crystallinity of the chips observed by micro-Raman spectroscopy and SEM was confirmed by HR-TEM showing dense occurrence of nanocrystals in the chips coming from the nanomachinings with 5-μm and 15-μm cutting depths. These results demonstrate potential of the single-point diamond machining for the preparation of high-quality X-ray surfaces with undistorted single-crystal lattice beneath for next-generation X-ray crystal optics.