Search

The processes of electrochemical deposition of Ni on vertically aligned GaAs nanowires (NWs) grown by molecular-beam epitaxy (MBE) using Au as a growth catalyst on n-type Si(111) substrates were studied. Based on the results of electrochemical deposition, it was concluded that during the MBE synthesis of NWs the self-induced formation of conductive channels can occur inside NWs, thereby forming quasi core-shell NWs. Depending on the length of the channel compare to the NW heights and the parameters of electrochemical deposition, the different hybrid metal-semiconductor nanostructures, such as Ni nanoparticles on GaAs NW side walls, Ni clusters on top ends of GaAs NWs, core-shell GaAs/Ni NWs, were obtained., (© 2025 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Interleukin-6 (IL-6) is a multifaceted cytokine essential in many immune system processes and their regulation. It also plays a key role in hematopoiesis, and in triggering the acute phase reaction. IL-6 overproduction is critical in chronic inflammation associated with autoimmune diseases like rheumatoid arthritis and contributes to cytokine storms in COVID-19 patients. Over 20 years ago, researchers proposed that IL-6, which is typically monomeric, can also form dimers via a domain-swap mechanism, with indirect evidence supporting their existence. The physiological significance of IL-6 dimers was shown in B-cell chronic lymphocytic leukemia. However, no structures have been reported so far. Here, we present the crystal structure of an IL-6 domain-swapped dimer that computational approaches could not predict. The structure explains why the IL-6 dimer is antagonistic to the IL-6 monomer in signaling complex formation and provides insights for IL-6 targeted therapies., Competing Interests: Declaration of interests N.P., S.R., A.I., and A.P. are inventors of the patent “Monoclonal antibody against human interleukin-6 and hybridoma producing this monoclonal antibody.” RU Patent 2 550 262 C1. (2015)., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Due to their high refractive index, record optical anisotropy and a set of excitonic transitions in visible range at a room temperature, transition metal dichalcogenides have gained much attention. Here, we adapted a femtosecond laser ablation for the synthesis of WSe 2 nanoparticles (NPs) with diameters from 5 to 150 nm, which conserve the crystalline structure of the original bulk crystal. This method was chosen due to its inherently substrate-additive-free nature and a high output level. The obtained nanoparticles absorb light stronger than the bulk crystal thanks to the local field enhancement, and they have a much higher photothermal conversion than conventional Si nanospheres. The highly mobile colloidal state of produced NPs makes them flexible for further application-dependent manipulations, which we demonstrated by creating substrates for SERS sensors.

Transition metal dichalcogenides (TMDCs), particularly molybdenum disulfide (MoS 2 ), have gained significant attention in the field of optoelectronics and photonics due to their unique electronic and optical properties. The integration of TMDCs with plasmonic materials allows to tailor the optical response and offers significant advantages for photonic applications. This study presents a novel approach to synthesize MoS 2 -Au nanocomposites utilizing femtosecond laser ablation in liquid to achieve tunable optical properties in the near-infrared (NIR) region. By adjusting ablation and fragmentation protocols, we successfully synthesize various core-shell and core-shell-satellite nanoparticle composites, such as MoS 2 /MoS x O y , MoS x O y /Au, and MoS 2 /MoS x O y /Au. UV-visible absorption spectroscopy unveils considerable changes in the optical response of the particles depending on the fabrication regime due to structural modifications. Hybrid nanoparticles exhibit enhanced photothermal properties when subjected to NIR-I laser irradiation, demonstrating potential benefits for selective photothermal therapy. Our findings underscore that the engineered nanocomposites not only facilitate green synthesis but also pave the way for tailored therapeutic applications, highlighting their role as promising candidates in the field of nanophotonics and cancer treatment.

Thin (~50 nm thick) BaM hexaferrite (BaFe 12 O 19 ) films were grown on (1-102) and (0001) cut α-Al 2 O 3 (sapphire) substrates via laser molecular beam epitaxy using a one- or two-stage growth protocol. The advantages of a two-stage protocol are shown. The surface morphology, structural and magnetic properties of films were studied using atomic force microscopy, reflected high-energy electron diffraction, three-dimensional X-ray diffraction reciprocal space mapping, powder X-ray diffraction, magneto-optical, and magnetometric methods. Annealed BaFe 12 O 19 /Al 2 O 3 (1-102) structures consist of close-packed islands epitaxially bonded to the substrate. The hexagonal crystallographic axis and the easy axis (EA) of the magnetization of the films are deflected from the normal to the film by an angle of φ ~60°. The films exhibit magnetic hysteresis loops for both in-plane H in-plane and out-of-plane H out-of-plane magnetic fields. The shape of M out-of-plane ( H in-plane ) and M in-plane ( H in-plane ) hysteresis loops strongly depends on the azimuth θ of the H in plane , confirming the tilted orientation of the EA. The M out-of-plane ( H out-of-plane ) magnetization curves are caused by the reversible rotation of magnetization and irreversible magnetization jumps associated with the appearance and motion of domain walls. In the absence of a magnetic field, the magnetization is oriented at an angle close to φ .

This study investigates the growth of gallium arsenide nanowires, using lead as a catalyst. Typically, nanowires are grown through the vapor-solid-liquid mechanism, where a key factor is the reduction in the nucleation barrier beneath the catalyst droplet. Arsenic exhibits limited solubility in conventional catalysts; however, this research explores an alternative scenario in which lead serves as a solvent for arsenic, while gallium and lead are immiscible liquids. Liquid lead easily dissolves in Si as well as in GaAs. The preservation of the catalyst during the growth process is also addressed. GaAs nanowires have been grown by molecular beam epitaxy on silicon Si (111) substrates at varying temperatures. Observations indicate the spontaneous doping of the GaAs nanowires with both lead and silicon. These findings contribute to a deeper understanding of the VLS mechanism involved in nanowire growth. They are also an important step in the study of GaAs nanowire-doping processes.

Increasing the InN content in the In x Ga 1- x N compound is paramount for optoelectronic applications. It has been demonstrated in homogeneous nanowires or deliberately grown nanowire heterostructures. Here, we present spontaneous core-shell In x Ga 1- x N nanowires grown by molecular beam epitaxy on Si substrates at 625 °C. These heterostructures have a high InN fraction in the cores around 0.4 and sharp interfaces, and exhibit bright photoluminescence at 650 nm. The surprising effect of material separation is attributed to the periodically changing environment for instantaneous growth of single monolayers on top of nanowires. Due to a smaller collection length of N adatoms, each monolayer nucleates under a balanced V/III ratio, but then continues under highly group III rich conditions. As a result, the miscibility gap is suppressed in the cores but remains in the shells. These results provide a simple method for obtaining high-quality InGaN heterostructures emitting in the extended wavelength range.

Semiconductor nanowires are known for their unusual geometry, providing unique electronic and optical properties. Substrates with vertical nanowires have highly non-uniform surfaces, which are attractive in terms of the study of live cells that can interact and be labeled with the wires. Despite several previous works studying cells cultivated over nanowires, questions regarding cell rupture and interaction with the wires remain open. Here, we demonstrate that nanowires can not only penetrate the cell membrane, but even be broken by a cell and trapped inside it. Even after mechanical poration of the membrane manifested by the efficient transfection and delivery of a fluorescent protein encoding plasmid, the cells are found to be viable for 7 days of incubation. The endocytosed wires are then aligned along the nucleus periphery and ousted to pseudopodia with the formation of nanowire-rich fibrils as a result of complex intracellular processes. We demonstrate that endocytosis of the wires may lead to their chemical modification manifested by the red shift of the luminescence spectra. Analysis of the wires' breakdown reveals that the cells can generate forces as high as several hundreds of nN. Using this work, we demonstrate several phenomena with the potential to be used in intriguing methods for intracellular visualization and the development of biointerfaces.

The C3f peptide is a by-product of regulation of the activated complement system with no firmly established function of its own. We have previously shown that C3f exhibits moderate antimicrobial activity against some Gram-positive bacteria in vitro . Presence of two histidine residues in the amino acid sequence of the peptide suggests enhancement of its antimicrobial activity at lower pH and in the presence of metal cations, particularly zinc cations. Since such conditions could be realized in inflammatory foci, the study of dependence of C3f activity on pH and presence of metal cations could provide an opportunity to assess biological significance of antimicrobial properties of the peptide. The peptide C3f and its analogs with histidine residues substituted by lysines or serines, C3f[H/K] and C3f[H/S], were prepared by solid-phase synthesis. Using CD spectroscopy, we found that C3f contained a β-hairpin and unstructured regions; presence of Zn 2+ did not affect conformation of the peptide. In the present work, it was shown that C3f could also exhibit antimicrobial activity against Gram-negative bacteria, in particular, Pseudomonas aeruginosa ATCC 27583. Exposure of P. aeruginosa and Listeria monocytogenes EGD to the peptide was accompanied by disruption of the barrier function of bacterial membranes. Zn 2+ ions, unlike Cu 2+ ions, enhanced antimicrobial activity of C3f against L. monocytogenes , with 4- and 8-fold molar excess of Zn 2+ being no more effective than a 20% excess. Activity of the C3f analogs was also enhanced to some extent by the zinc ions. Thus, we hypothesize existence of the histidine-independent formation of C3f-Zn 2+ complexes leading to increase in the total charge and antimicrobial activity of the peptide. In the presence of 0.15 M NaCl, C3f lost its antimicrobial activity regardless of the presence of Zn 2+ , indicating an insignificant role of C3f as an endogenous antimicrobial peptide. Presence of C3f eliminated bactericidal effect of Zn 2+ against the zinc-sensitive Escherichia coli strain ESBL 521/17, indirectly confirming interaction of the peptide with Zn 2+ . Activity of C3f against Micrococcus luteus A270 increased with decreasing pH, while effect of pH on the C3f activity against L. monocytogenesis was more complex. In this work, we show significance of the factors such as pH and metal cations in realization of antimicrobial activity of peptides based on the example of C3f.

Innovative methods for substrate patterning provide intriguing possibilities for the development of devices based on ordered arrays of semiconductor nanowires. Control over the nanostructures' morphology in situ can be obtained via extensive theoretical studies of their formation. In this paper, we carry out an investigation of the ordered nanowires' formation kinetics depending on the growth mask geometry. Diffusion equations for the growth species on both substrate and nanowire sidewalls depending on the spacing arrangement of the nanostructures and deposition rate are considered. The value of the pitch corresponding to the maximum diffusion flux from the substrate is obtained. The latter is assumed to be the optimum in terms of the nanowire elongation rate. Further study of the adatom kinetics demonstrates that the temporal dependence of a nanowire's length is strongly affected by the ratio of the adatom's diffusion length on the substrate and sidewalls, providing insights into the proper choice of a growth wafer. The developed model allows for customization of the growth protocols and estimation of the important diffusion parameters of the growth species.

Authentication of a product's originality by anticounterfeiting labels represents a crucial point toward protection against forgery. Fast and scalable fabrication methods of original labels with a high degree of protection are in high demand for the protection of valuable goods. Here, we propose a simple strategy for fabrication of hidden security tags with IR luminescent readout by the direct femtosecond laser patterning of silicon-erbium-silicon sandwiched thin films. The choice of laser processing parameters makes possible the creation of random or quasi-regular self-organized surface nanotextures. The controlled laser-driven oxidation accompanying this process provides simultaneous regulation of the film's optical properties and spontaneous emission yield of the embedded Er atoms. The regimes are detected when optically similar patterned areas demonstrate different Er emission intensities, allowing us to create hidden security tags with facile readout at the C-band telecommunication wavelengths. The obtained results take another step toward the application of IR-luminescent erbium-based anticounterfeiting labels for covert and/or forensic security levels.

Nanostructured ultraviolet (UV) light sources represent a growing research field in view of their potential applications in wearable optoelectronics or medical treatment devices. In this work, we report the demonstration of the first flexible UV-A light emitting diode (LED) based on AlGaN/GaN core-shell microwires. The device is based on a composite microwire/poly(dimethylsiloxane) (PDMS) membrane with flexible transparent electrodes. The electrode transparency in the UV range is optimized: namely, we demonstrate that single-walled carbon nanotube electrodes provide a stable electrical contact to the membrane with high transparency (70% at 350 nm). The flexible UV-A membrane demonstrating electroluminescence around 345 nm is further applied to excite Zn-Ir-BipyPDMS luminophores: the UV-A LED is combined with the elastic luminophore-containing membrane to produce a visible amber emission from 520 to 650 nm. The obtained results pave the way for flexible inorganic light-emitting diodes to be employed in sensing, detection of fluorescent labels, or light therapy.

This work demonstrates the use of a solid-state nanopore detector to monitor the activity of a single molecule of a model enzyme, horseradish peroxidase (HRP). This detector includes a measuring cell, which is divided into cis- and trans- chambers by a silicon nitride chip (SiN structure) with a nanopore of 5 nm in diameter. To entrap a single HRP molecule into the nanopore, an electrode had been placed into the cis-chamber; HRP solution was added into this chamber after application of a negative voltage. The reaction of the HRP substrate, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), oxidation by the enzyme molecule was performed in the presence of hydrogen peroxide. During this reaction, the functioning of a single HRP molecule, entrapped in the nanopore, was monitored by recording the time dependence of the ion current flowing through the nanopore. The approach proposed in our work is applicable for further studies of functioning of various enzymes at the level of single molecules, and this is an important step in the development of single-molecule enzymology.

Efficient second harmonic generation and broad-band photoluminescence from deeply subwavelength and nontoxic nanoparticles is essential for nanophotonic applications. Here, we explore nonlinear optical response from mesoporous Si/SiO 2 , SiO 2 , and Si nanoparticles, considering various fabrication and treatment procedures. We show that thermal annealing (including femtosecond laser treatment) of mesoporous Si/SiO 2 nanoparticles provides the transformation of Si phase from amorphous to crystalline, enhancing the second harmonic and nonlinear photoluminescent response. Notably, the SiO 2 mesoporous frame of the considered Si/SiO 2 nanoparticles plays a dual positive role for the nonlinear process: it stabilizes the Si material, and SiO 2 :OH - material has a second-order nonlinearity itself and impacts to the observed second harmonic signal., Competing Interests: Conflict of interest: Authors state no conflicts of interest., (© 2024 the author(s), published by De Gruyter, Berlin/Boston.)

Innate immunity of invertebrates offers potent antimicrobial peptides (AMPs) against drug-resistant infections. To identify new worm β-hairpin AMPs, we explored the sequence diversity of proteins with a BRICHOS domain, which comprises worm AMP precursors. Strikingly, we discovered new BRICHOS AMPs not in worms, but in caecilians, the least studied clade of vertebrates. Two precursor proteins from Microcaecilia unicolor and Rhinatrema bivittatum resemble SP-C lung surfactants and bear worm AMP-like peptides at C-termini. The analysis of M. unicolor tissue transcriptomes shows that the AMP precursor is highly expressed in the lung along with regular SP-C, suggesting a different, protective function. The peptides form right-twisted β-hairpins, change conformation upon lipid binding, and rapidly disrupt bacterial membranes. Both peptides exhibit broad-spectrum activity against multidrug-resistant ESKAPE pathogens with 1-4 μM MICs and remarkably low toxicity, giving 40-70-fold selectivity towards bacteria. These BRICHOS AMPs, previously unseen in vertebrates, reveal a novel lung innate immunity mechanism and offer a promising antibiotics template., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ruslan Smetanin, Olga Shamova and Igor Eliseev have patent pending to Institute of Experimental Medicine. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Two sodium phosphate glasses with different structure (meta- and orthophosphate ones) were thermally poled well below the glass transition temperatures. Glass with an orthophosphate structure (glass LA30) demonstrated a typical behavior of polarization current, that is, monotonic current decrease; however, in glass with a metaphosphate structure (glass LA10) the current first increased for 15-20 min and only then started monotonic decreasing. In spite of the similar sodium content, the current in LA10 glass exceeded the one in LA30 glass by about 10 times. This is explained by the capability of substituting intrinsic sodium ions by more mobile protons entering LA10 glass with a metaphosphate structure from the atmosphere. The other difference consists in the fact that the subanodic layer of LA10 glass after poling has many small cracks, while the subanodic layer of LA30 glass is crystallized. It should be emphasized that the crystallization of phosphate glasses under dc electric field below glass transition temperature is observed for the first time. In addition, after poling, no changes in the refractivity of both glasses were detected, but the generation of the second optical harmonic in LA30 glass was observed., (© 2024 IOP Publishing Ltd.)

Redox-responsive drug delivery systems present a promising avenue for drug delivery due to their ability to leverage the unique redox environment within tumor cells. In this work, we describe a facile and cost-effective one-pot synthesis method for a redox-responsive delivery system based on novel trithiocyanuric acid (TTCA) nanoparticles (NPs). We conduct a thorough investigation of the impact of various synthesis parameters on the morphology, stability, and loading capacity of these NPs. The great drug delivery potential of the system is further demonstrated in vitro and in vivo by using doxorubicin as a model drug. The developed TTCA-PEG NPs show great drug delivery efficiency with minimal toxicity on their own both in vivo and in vitro . The simplicity of this synthesis, along with the promising characteristics of TTCA-PEG NPs, paves the way for new opportunities in the further development of redox-responsive drug delivery systems based on TTCA.

Electric field is a powerful instrument in nanoscale engineering, providing wide functionalities for control in various optical and solid-state nanodevices. The development of a single optically resonant nanostructure operating with a charge-induced electrical field is challenging, but it could be extremely useful for novel nanophotonic horizons. Here, we show a resonant metal-semiconductor nanostructure with a static electric field created at the interface between its components by charge carriers generated via femtosecond laser irradiation. We study this field experimentally, probing it by second-harmonic generation signal, which, in our system, is time-dependent and has a non-quadratic signal/excitation power dependence. The developed numerical models reveal the influence of the optically induced static electric field on the second harmonic generation signal. We also show how metal work function and silicon surface defect density for different charge carrier concentrations affect the formation of this field. We estimate the value of optically-generated static electric field in this nanoantenna to achieve ≈10 8 V/m. These findings pave the way for the creation of nanoantenna-based optical memory, programmable logic and neuromorphic devices., (© 2023. Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), CAS.)

We reveal a novel phenomenon observed after self-catalytic growth of GaAs nanowires (NWs) on Si(111) substrates treated with a Ga focused ion beam (FIB). Depending on the ion dose, NW arrays with various geometrical parameters can be obtained. A minor treatment of the substrate enables a slight increase in the surface density of NWs relative to an unmodified substrate area. As the ion dose is increased up to ∼0.1 pC μ m -2 , the growth of GaAs NWs and nanocrystals is suppressed. However, a further increase in the ion dose stimulates the crystal growth leading to the formation of extremely thin NWs (39 ± 5 nm) with a remarkably high surface density of up to 15 μ m -2 . Resting upon an analysis of the surface structure before and after stages of ion-beam treatment, ultra-high vacuum annealing and NW growth, we propose a mechanism underlying the phenomenon observed. We assume that the chemical interaction between embedded Ga ions and a native Si oxide layer leads either to the enhancement of the passivation properties of the oxide layer within FIB-modified areas (at low and middle ion doses), or to the etching of the passivating oxide layer by excess Ga atoms, resulting in the formation of pores (at high ion doses). Due to this behavior, local fabrication of GaAs NW arrays with a diverse range of characteristics can be implemented on the same substrate. This approach opens a new way for self-catalytic growth of GaAs NWs., (© 2023 IOP Publishing Ltd.)

AlF 3 has interesting electrophysical properties, due to which the material is promising for applications in supercapacitors, UV coatings with low refractive index, excimer laser mirrors, and photolithography. The formation of AlF 3 -based nano- and micro-wires can bring new functionalities to AlF 3 material. AlF 3 nanowires are used, for example, in functionally modified microprobes for a scanning probe microscope. In this work, we investigate the AlF 3 samples obtained by the reaction of initial aluminum with an aqueous hydrofluoric acid solution of different concentrations. The peculiarity of our work is that the presented method for the synthesis of AlF 3 and one-dimensional structures based on AlF 3 is simple to perform and does not require any additional precursors or costs related to the additional source materials. All the samples were obtained under normal conditions. The morphology of the nanowire samples is studied using scanning electron microscopy. We performed an intermediate atomic force microscope analysis of dissolved Al samples to analyze the reactions occurring on the metal surface. The surface of the obtained samples was analyzed using a scanning electron microscope. During the analysis, it was found that under the given conditions, whiskers were synthesized. The scale of one-dimensional structures varies depending on the given parameters in the system. Quantitative energy-dispersive x-ray spectroscopy spectra are obtained and analyzed with respect to the feedstock and each other.

Hybrid ferromagnet-semiconductor systems possess new outstanding properties, which emerge when bringing magnetic and semiconductor materials into contact. In such structures, the long-range magnetic proximity effect couples the spin systems of the ferromagnet and semiconductor on distances exceeding the carrier wave function overlap. The effect is due to the effective p-d exchange interaction of acceptor-bound holes in the quantum well with d-electrons of the ferromagnet. This indirect interaction is established via the phononic Stark effect mediated by the chiral phonons. Here, we demonstrate that the long-range magnetic proximity effect is universal and observed in hybrid structures with diverse magnetic components and potential barriers of various thicknesses and compositions. We study hybrid structures consisting of a semimetal (magnetite Fe3O4) or dielectric (spinel NiFe2O4) ferromagnet and a CdTe quantum well separated by a nonmagnetic (Cd,Mg)Te barrier. The proximity effect is manifested in the circular polarization of the photoluminescence corresponding to the recombination of photoexcited electrons with holes bound to shallow acceptors in the quantum well induced by magnetite or spinel itself, in contrast to interface ferromagnet in case of metal-based hybrid systems. A nontrivial dynamics of the proximity effect is observed in the studied structures due to recombination-induced dynamic polarization of electrons in the quantum well. It enables the determination of the exchange constant Δexch ≈ 70 μeV in a magnetite-based structure. The universal origin of the long-range exchange interaction along with the possibility of its electrical control offers prospects for the development of low-voltage spintronic devices compatible with existing solid-state electronics., (© 2023 Author(s). Published under an exclusive license by AIP Publishing.)

Emerging technologies for integrated optical circuits demand novel approaches and materials. This includes a search for nanoscale waveguides that should satisfy criteria of high optical density, small cross-section, technological feasibility and structural perfection. All these criteria are met with self-assembled gallium phosphide (GaP) epitaxial nanowires. In this work, the effects of the nanowire geometry on their waveguiding properties are studied both experimentally and numerically. Cut-off wavelength dependence on the nanowire diameter is analyzed to demonstrate the pathways for fabrication of low-loss and subwavelength cross-section waveguides for visible and near-infrared (IR) ranges. Probing the waveguides with a supercontinuum laser unveils the filtering properties of the nanowires due to their resonant action. The nanowires exhibit perfect elasticity allowing fabrication of curved waveguides. It is demonstrated that for the nanowire diameters exceeding the cut-off value, the bending does not sufficiently reduce the field confinement promoting applicability of the approach for the development of nanoscale waveguides with a preassigned geometry. Optical X-coupler made of two GaP nanowires allowing for spectral separation of the signal is fabricated. The results of this work open new ways for the utilization of GaP nanowires as elements of advanced photonic logic circuits and nanoscale interferometers., (© 2023 Wiley-VCH GmbH.)

Semiconductor lasers have developed rapidly with the steady growth of the global laser market. The use of semiconductor laser diodes is currently considered to be the most advanced option for achieving the optimal combination of efficiency, energy consumption, and cost parameters of high-power solid-state and fiber lasers. In this work, an approach for optical mode engineering in planar waveguides is investigated. The approach referred to as Coupled Large Optical Cavity (CLOC) is based on the resonant optical coupling between waveguides and allows the selection of high-order modes. The state-of-art of the CLOC operation is reviewed and discussed. We apply the CLOC concept in our waveguide design strategy. The results in both numerical simulation and experiment show that the CLOC approach can be considered a simple and cost-efficient solution for improving diode laser performance.

We present a study with a numerical model based on k→·p→, including electromechanical fields, to evaluate the electromechanical and optoelectronic properties of single GaAs quantum dots embedded in direct band gap AlGaAs nanowires. The geometry and the dimensions of the quantum dots, in particular the thickness, are obtained from experimental data measured by our group. We also present a comparison between the experimental and numerically calculated spectra to support the validity of our model.

The facile synthesis of biografted 2 D derivatives complemented by a nuanced understanding of their properties are keystones for advancements in biosensing technologies. Herein, we thoroughly examine the feasibility of aminated graphene as a platform for the covalent conjugation of monoclonal antibodies towards human IgG immunoglobulins. Applying core-level spectroscopy methods, namely X-ray photoelectron and absorption spectroscopies, we delve into the chemistry and its effect on the electronic structure of the aminated graphene prior to and after the immobilization of monoclonal antibodies. Furthermore, the alterations in the morphology of the graphene layers upon the applied derivatization protocols are assessed by electron microscopy techniques. Chemiresistive biosensors composed of the aerosol-deposited layers of the aminated graphene with the conjugated antibodies are fabricated and tested, demonstrating a selective response towards IgM immunoglobulins with a limit of detection as low as 10 pg/mL. Taken together, these findings advance and outline graphene derivatives' application in biosensing as well as hint at the features of the alterations of graphene morphology and physics upon its functionalization and further covalent grafting by biomolecules.

Nonlinear silicon photonics has a high compatibility with CMOS technology and therefore is particularly attractive for various purposes and applications. Second harmonic generation (SHG) in silicon nanowires (NWs) is widely studied for its high sensitivity to structural changes, low-cost fabrication, and efficient tunability of photonic properties. In this study, we report a fabrication and SHG study of Si nanowire/siloxane flexible membranes. The proposed highly transparent flexible membranes revealed a strong nonlinear response, which was enhanced via activation by an infrared laser beam. The vertical arrays of several nanometer-thin Si NWs effectively generate the SH signal after being exposed to femtosecond infrared laser irradiation in the spectral range of 800-1020 nm. The stable enhancement of SHG induced by laser exposure can be attributed to the functional modifications of the Si NW surface, which can be used for the development of efficient nonlinear platforms based on silicon. This study delivers a valuable contribution to the advancement of optical devices based on silicon and presents novel design and fabrication methods for infrared converters.

Gallium nitride (GaN) is one of the most promising materials for high-frequency devices owing to its prominent material properties. We report on the fabrication and study of a series of Schottky diodes in the ground-signal-ground topology based on individual GaN nanowires. The electrical characterization of I - V curves demonstrated relatively high ideality factor value (about 6-9) in comparison to the planar Au/GaN diodes that can be attributed to the nanowire geometry. The effective barrier height in the studied structures was defined in the range of 0.25-0.4 eV. The small-signal frequency analysis was employed to study the dependency of the scattering parameters in the broad range from 0.1 to 40 GHz. The approximation fitting of the experimental data indicated the record high cutoff frequency of about 165.8 GHz., (© 2023 IOP Publishing Ltd.)

Hybrid nanostructures based on InGaN nanowires with decorated plasmonic silver nanoparticles are investigated in the present study. It is shown that plasmonic nanoparticles induce the redistribution of room temperature photoluminescence between short-wavelength and long-wavelength peaks of InGaN nanowires. It is defined that short-wavelength maxima decreased by 20%, whereas the long-wavelength maxima increased by 19%. We attribute this phenomenon to the energy transfer and enhancement between the coalesced part of the NWs with 10-13% In content and the tips above with an In content of about 20-23%. A proposed Fröhlich resonance model for silver NPs surrounded by a medium with refractive index of 2.45 and spread 0.1 explains the enhancement effect, whereas the decreasing of the short-wavelength peak is associated with the diffusion of charge carriers between the coalesced part of the NWs and the tips above.

Wurtzite AlGaAs is a technologically promising yet unexplored material. Here we study it both experimentally and numerically. We develop a complete numerical model based on an 8-band k → · p → method, including electromechanical fields, and calculate the optoelectronic properties of wurtzite AlGaAs nanowires with different Al content. We then compare them with our experimental data. Our results strongly suggest that wurtzite AlGaAs is a direct band gap material. Moreover, we have also numerically obtained the band gap of wurtzite AlAs and the valence band offset between AlAs and GaAs in the wurtzite symmetry.

Semiconductor nanowires are the perfect platform for nanophotonic applications owing to their resonant, waveguiding optical properties and technological capabilities providing control over their crystalline and chemical compositions. The vapor-liquid-solid growth mechanism allows the formation of hybrid metal-dielectric nanostructures promoting sub-wavelength light manipulation. In this work, we explore both experimentally and numerically the plasmonic effects promoted by a gallium (Ga) nanoparticle optical antenna decorating the facet of gallium phosphide (GaP) nanowires. Raman, photoluminescence and near-field mapping techniques are used to study the effects. We demonstrate several phenomena including field enhancement, antenna effect and increase in internal reflection. We show that the observed effects have to be considered when nanowires with a plasmonic particle are used in nanophotonic circuits and discuss the ways for utilization of these effects for efficient coupling of light into nanowire waveguide and field tailoring. The results open up promising pathways for the development of both passive and active nanophotonic elements, light harvesting and sensorics.

Red blood cells (RBCs) are the most numerous cells in the body and perform gas exchange between all tissues. During the infusion of cancer chemotherapeutic (CT) agents, blood cells are the first ones to encounter aggressive cytostatics. Erythrocyte dysfunction caused by direct cytotoxic damage might be a part of the problem of chemotherapy-induced anemia-one of the most frequent side effects. The aim of the current study is to evaluate the functional status of RBCs exposed to mono and combinations of widely used commercial pharmaceutical CT drugs with different action mechanisms: paclitaxel, carboplatin, cyclophosphamide, and doxorubicin, in vitro. Using laser diffraction, flow cytometry, and confocal microscopy, we show that paclitaxel, having a directed effect on cytoskeleton proteins, by itself and in combination with carboplatin, caused the most marked abnormalities-loss of control of volume regulation, resistance to osmotic load, and stomatocytosis. Direct simulations of RBCs' microcirculation in microfluidic channels showed both the appearance of a subpopulation of cells with impaired velocity (slow damaged cells) and an increased number of cases of occlusions. In contrast to paclitaxel, such drugs as carboplatin, cyclophosphamide, and doxorubicin, whose main target in cancer cells is DNA, showed significantly less cytotoxicity to erythrocytes in short-term exposure. However, the combination of drugs had an additive effect. While the obtained results should be confirmed in in vivo models, one can envisioned that such data could be used for minimizing anemia side effects during cancer chemotherapy.

Zinc oxide (ZnO) nanostructures are widely used in various fields of science and technology due to their properties and ease of fabrication. To achieve the desired characteristics for subsequent device application, it is necessary to develop growth methods allowing for control over the nanostructures' morphology and crystallinity governing their optical and electronic properties. In this work, we grow ZnO nanostructures via hydrothermal synthesis using surfactants that significantly affect the growth kinetics. Nanostructures with geometry from nanowires to hexapods are obtained and studied with photoluminescence (PL) spectroscopy. Analysis of the photoluminescence spectra demonstrates pronounced exciton on a neutral donor UV emission in all of the samples. Changing the growth medium chemical composition affects the emission characteristics sufficiently. Apart the UV emission, nanostructures synthesized without the surfactants demonstrate deep-level emission in the visible range with a peak near 620 nm. Structures synthesized with the use of sodium citrate exhibit emission peak near 520 nm, and those with polyethylenimine do not exhibit the deep-level emission. Thus, we demonstrate the correlation between the hydrothermal growth conditions and the obtained ZnO nanostructures' optical properties, opening up new possibilities for their precise control and application in nanophotonics, UV-Vis and white light sources.

This paper presents the results of experimental studies of the effect of Si(111) surface modification by Ga-focused ion beam (FIB) at 30 kV accelerating voltage on the features of the epitaxial GaAs nanowire (NW) growth processes. We experimentally established the regularities of the Ga ions' dose effect during surface modification on the structural characteristics of GaAs NW arrays. Depending on the Ga ion dose value, there is one of three modes on the surface for subsequent GaAs NW growth. At low doses, the NW growth is almost completely suppressed. The growth mode of high-density (up to 6.56 µm -2 ) GaAs NW arrays with a maximum fraction (up to 70%) of nanowires normally oriented to the substrate is realized in the medium ion doses range. A continuous polycrystalline base with a dense array of misoriented short (up to 0.9 µm) and thin (up to 27 nm) GaAs NWs is formed at high doses. We assume that the key role is played by the interaction of the implanted Ga ions with the surface at various process stages and its influence on the surface structure in the modification region and on GaAs NW growth conditions.

We study photoluminescence of InP/InAsP/InP nanostructures monolithically integrated to a Si(100) substrate. The InP/InAsP/InP nanostructures were grown in pre-formed pits in the silicon substrate using an original approach based on selective area growth and driven by a molten alloy in metal-organic vapor epitaxy method. This approach provides the selective-area synthesis of the ordered emitters arrays on Si substrates. The obtained InP/InAsP/InP nanostructures have a submicron size. The individual InP/InAsP/InP nanostructures were investigated by photoluminescence spectroscopy at room temperature. The tuning of the emission line in the spectral range from 1200 nm to 1550 nm was obtained depending on the growth parameters. These results provide a path for the growth on Si(100) substrate of position-controlled heterojunctions based on InAs 1-x P x for nanoscale optical devices operating at the telecom band.

For the first time we show that the introduction of silver ions in the glass containing gold nanoparticles (NPs) and additional heat treatment of the glass in the air lead to the formation of Au/Ag alloy NPs. The proposed approach makes it possible to position localized surface plasmon resonance of the NPs by selecting the heat treatment temperature, which determines the silver proportion in the alloy NPs. This allows for expanding customizability of NPs for applications in surface-enhanced Raman scattering spectroscopy, catalysis and biochemistry. Developed technique benefits from the presence of silver in the glass in ionic form, which prevents the oxidation of silver and provides stable preparation of Au/Ag alloy NPs.

It has been experimentally shown for the first time that metallic copper in glasses can play the role of a reducing agent for other metallic ions, in particular, resulting in the formation of metal nanoparticles. Silver ions have been introduced into an alkali silicate glass containing copper nanoparticles by ion exchange. This has resulted in the formation of silver nanoparticles accompanied by the disappearance of copper nanoparticles initially contained in the glass. Such a process has never been observed and described anywhere. The process has been explained by the redox reaction Cu 0 + Ag + → Cu + + Ag 0 taking place in silver ion exchange. It has been shown that this reaction can go only in one direction (from left to right) as a result of the relative positions of copper and silver in the activity series.

Photothermal therapy (PTT) has attracted increasing interest as a complementary method to be used alongside conventional therapies. Despite a great number of studies in this field, only a few have explored how temperatures affect the outcome of the PTT at nanoscale. In this work, we study the necrosis/apoptosis process of cancerous cells that occurs during PTT, using a combination of local laser heating and nanoscale fluorescence thermometry techniques. The temperature distribution within a whole cell was evaluated using fluorescence lifetime imaging microscopy during laser-induced hyperthermia. For this, gold nanorods were utilized as nanoheaters. The local near-infrared laser illumination produces a temperature gradient across the cells, which is precisely measured by nanoscale thermometry. This allows one to optimize the PTT conditions by varying concentration of gold nanorods associated with cells and laser power density. During the PTT procedure, such an approach enables an accurate determination of the percentages of apoptotic and necrotic cells using 2D and 3D models. According to the performed cell experiments, the influence of temperature increase during the PTT on cell death mechanisms has been verified and determined. Our investigations can improve the understanding of the PTT mechanisms and increase its therapeutic efficiency while avoiding any side effects., (© 2022 the author(s), published by De Gruyter, Berlin/Boston.)

We studied the surface-enhanced Raman spectra of amino acids D -alanine and DL -serine and their mixture on silver nanoisland films (SNF) immersed in phosphate-buffered saline (PBS) solution at millimolar amino acid concentrations. It is shown that the spectra from the amino acid solutions differ from the reference spectra for microcrystallites due to the electrostatic orientation of amino acid zwitterions by the metal nanoisland film. Moreover, non-additive peaks are observed in the spectrum of the mixture of amino acids adsorbed on SNF, which means that intermolecular interactions between adsorbed amino acids are very significant. The results indicate the need for a thorough analysis of the Raman spectra from amino acid solutions, particularly, in PBS, in the presence of a nanostructured silver surface, and may also be of interest for studying molecular properties and intermolecular interactions.

The rapid detection of pollutants in water can be performed with enzymatic probes, the catalytic light-emitting activity of which decreases in the presence of many types of pollutants. Herein, we present a microfluidic system for continuous chemoenzymatic biosensing that generates emulsion droplets containing two enzymes of the bacterial bioluminescent system (luciferase and NAD(P)H:FMN-oxidoreductase) with substrates required for the reaction. The developed chip generates "water-in-oil" emulsion droplets with a volume of 0.1 μL and a frequency of up to 12 drops per minute as well as provides the efficient mixing of reagents in droplets and their distancing. The bioluminescent signal from each individual droplet was measured by a photomultiplier tube with a signal-to-noise ratio of up to 3000/1. The intensity of the luminescence depended on the concentration of the copper sulfate with the limit of its detection of 5 μM. It was shown that bioluminescent enzymatic reactions could be carried out in droplet reactors in dispersed streams. The parameters and limitations required for the bioluminescent reaction to proceed were also studied. Hereby, chemoenzymatic sensing capabilities powered by a droplet microfluidics manipulation technique may serve as the basis for early-warning online water pollution systems.

GaN nanowires were grown using selective area plasma-assisted molecular beam epitaxy on SiO x /Si(111) substrates patterned with microsphere lithography. For the first time, the temperature-Ga/N 2 flux ratio map was established for selective area epitaxy of GaN nanowires. It is shown that the growth selectivity for GaN nanowires without any parasitic growth on a silica mask can be obtained in a relatively narrow range of substrate temperatures and Ga/N 2 flux ratios. A model was developed that explains the selective growth range, which appeared to be highly sensitive to the growth temperature and Ga flux, as well as to the radius and pitch of the patterned pinholes. High crystal quality in the GaN nanowires was confirmed through low-temperature photoluminescence measurements.

Oxidative stress is one of the key factors that leads to red blood cells (RBCs) aging, and impairs their biomechanics and oxygen delivery. It occurs during numerous pathological processes and causes anaemia, one of the most frequent side effects of cancer chemotherapy. Here, we used microfluidics to simulate the microcirculation of RBCs under oxidative stress induced by tert-Butyl hydroperoxide. Oxidative stress was expected to make RBCs more rigid, which would lead to decrease their transit velocity in microfluidic channels. However, single-cell tracking combined with cytological and AFM studies reveals cell heterogeneity, which increases with the level of oxidative stress. The data indicates that the built-in antioxidant defence system has a limit exceeding which haemoglobin oxidation, membrane, and cytoskeleton transformation occurs. It leads to cell swelling, increased stiffness and adhesion, resulting in a decrease in the transit velocity in microcapillaries. However, even at high levels of oxidative stress, there are persistent cells in the population with an undisturbed biophysical phenotype that retain the ability to move in microcapillaries. Developed microfluidic analysis can be used to determine RBCs' antioxidant capacity for the minimization of anaemia during cancer chemotherapy., (© 2022. The Author(s).)

For the first time, we demonstrated that additional poling at room temperature (cold repoling) of a soda-lime glass thermally poled in open anode configuration causes an increase of the optical second harmonic signal by more than an order of magnitude. Performed experiments allow relating this increase in the optical nonlinearity of the glass to the orientation of hydrogenated dipoles in the vicinity of the glass surface. This indicates that both frozen electric field and dipole orientation are responsible for the nonlinearity of thermally poled alkali-containing glasses. Observed dipole orientation in glasses is of interest for molecular physics and electrodynamic studies.

The direct integration of epitaxial III-V and III-N heterostructures on Si substrates is a promising platform for the development of optoelectronic devices. Nanowires, due to their unique geometry, allow for the direct synthesis of semiconductor light-emitting diodes (LED) on crystalline lattice-mismatched Si wafers. Here, we present molecular beam epitaxy of regular arrays n-GaN/i-InGaN/p-GaN heterostructured nanowires and tripods on Si/SiO 2 substrates prepatterned with the use of cost-effective and rapid microsphere optical lithography. This approach provides the selective-area synthesis of the ordered nanowire arrays on large-area Si substrates. We experimentally show that the n-GaN NWs/n-Si interface demonstrates rectifying behavior and the fabricated n-GaN/i-InGaN/p-GaN NWs-based LEDs have electroluminescence in the broad spectral range, with a maximum near 500 nm, which can be employed for multicolor or white light screen development.

It is very natural to use silicon as a primary material for microelectronics. However, silicon application in nanophotonics is limited due to the indirect gap of its energy band structure. To improve the silicon emission properties, it can be combined with a plasmonic part. The resulting metal-dielectric (hybrid) nanostructures have shown their excellence compared to simple metallic dielectric nanostructures. Still, in many cases, the fabrication of such structures is time consuming and quite difficult. Here, for the first time, we demonstrate a single-step and lithography-free laser-induced dewetting of bi-layer nanoscale-thickness gold-silicon films supported by a glass substrate to produce hybrid nanoparticles. For obtaining hybrid nanoparticles, we study nonlinear photoluminescence by mapping their optical response and morphology by scanning electron microscopy. This method can be used for the fabrication of arrays of hybrid nanoparticles providing white-light photoluminescence with a good control of their microscopic sizes and position. The developed approach can be useful for a wide range of photonic applications including the all-optical data processing and storage where miniaturization down to micro- and nanoscale together with an efficiency increase is of high demand.

The outstanding optical properties and multiphoton absorption of lead halide perovskites make them promising for use as fluorescence tags in bioimaging applications. However, their poor stability in aqueous media and biological fluids significantly limits their further use for in vitro and in vivo applications. In this work, we have developed a universal approach for the encapsulation of lead halide perovskite nanocrystals (PNCs) (CsPbBr 3 and CsPbI 3 ) as water-resistant fluorescent markers, which are suitable for fluorescence bioimaging. The obtained encapsulated PNCs demonstrate bright green emission at 510 nm (CsPbBr 3 ) and red emission at 688 nm (CsPbI 3 ) under one- and two-photon excitation, and they possess an enhanced stability in water and biological fluids (PBS, human serum) for a prolonged period of time (1 week). Further in vitro and in vivo experiments revealed enhanced stability of PNCs even after their introduction directly into the biological microenvironment (CT26 cells and DBA mice). The developed approach allows making a step toward stable, low-cost, and highly efficient bioimaging platforms that are spectrally tunable and have narrow emission.