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Inspired by the easy intercalation of quinoxaline heterocyclic aromatic amines (HAAs) in double-stranded DNA (dsDNA), we synthesized a nucleobase-functionalized molecularly imprinted polymer (MIP) as the recognition unit of an impedimetric chemosensor for the selective determination of a 2-amino-3,7,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (7,8-DiMeIQx) HAA. HAAs are generated in meat and fish processed at high temperatures. They are considered to be potent hazardous carcinogens. The MIP film was prepared by potentiodynamic electropolymerization of a pre-polymerization complex of two adenine- and one thymine-substituted bis(2,2′-bithien-5-yl)methane functional monomer molecules with one 7,8-DiMeIQx template molecule, in the presence of the 2,4,5,2′,4′,5′-hexa(thiophene-2-yl)-3,3′-bithiophene cross-linking monomer, in solution. The as-formed MIP chemosensor allowed for the selective impedimetric determination of 7,8-DiMeIQx in the 47 to 400 μM linear dynamic concentration range with a limit of detection of 15.5 μM. The chemosensor was successfully applied for 7,8-DiMeIQx determination in the pork meat extract as a proof of concept.

TCR signaling critically depends on the tyrosine kinase Lck (lymphocyte-specific protein tyrosine kinase). Two phosphotyrosines, the activating pTyr394 and the inhibitory pTyr505, control Lck activity. Recently, pTyr192 in the Lck SH2 domain emerged as a third regulator. How pTyr192 may affect Lck function remains unclear. In this study, we explored the role of Lck Tyr192 using CRISPR/Cas9-targeted knock-in mutations in the human Jurkat T cell line. Our data reveal that both Lck pTyr394 and pTyr505 are controlled by Lck Tyr192. Lck with a nonphosphorylated SH2 domain (Lck Phe192) displayed hyperactivity, possibly by promoting Lck Tyr394 transphosphorylation. Lck Glu192 mimicking stable Lck pTyr192 was inhibited by Tyr505 hyperphosphorylation. To overcome this effect, we further mutated Tyr505. The resulting Lck Glu192/Phe505 displayed strongly increased amounts of pTyr394 both in resting and activated T cells. Our results suggest that a fundamental role of Lck pTyr192 may be to protect Lck pTyr394 and/or pTyr505 to maintain a pool of already active Lck in resting T cells. This provides an additional mechanism for fine-tuning of Lck as well as T cell activity.

To maintain homeostasis, all cells respond to environmental cues via a multitude of surface receptors. In order to act appropriately in their environment, cells are dependent on the transduction of the incoming signal through tightly regulated and interconnected signalling pathways to the cell nucleus. In particular, cells implicated in the immune system greatly depend on such systems to respond in a flexible and dynamic manner to environmental challenges. One major group of intracellular proteins that are involved in these signalling pathways are adaptor proteins. Although adaptor proteins are essential for normal immune cell operation, the functional role of this group of signalling proteins remains to be fully appreciated. So far, research on adaptor proteins has revealed their unique potential in building transient complexes in a reversible, dynamic and inducible manner. In this review, we explore the roles of adaptor proteins – in space and time of intracellular signalling – and their associations with human disease. Examples of adaptor proteins expressed in hematopoietic cells highlight their crucial role in the immune system. Lastly, we present challenges faced in elucidating roles of adaptor proteins, as illustrated by the T cell–specific adaptor (TSAd) protein encoded by the SH2D2A gene.

A chemosensor with a molecularly imprinted polymer (MIP) film as the recognition unit selective to a carnosine biomarker was molecularly engineered, devised and fabricated. The molecular structure of the pre-polymerization complex of the carnosine template with the carboxy and 18-crown-6 ether derivatives of bis(2,2′-bithien-5-yl)methane functional monomers was thermodynamically optimized by density functional theory (DFT) at the B3LYP/6-31g(d) level. The calculated high negative Gibbs free energy change, ΔG = −227.4 kJ mol−1, indicated the formation of a very stable complex. The solution of this complex was prepared and used for deposition of the MIP films on a Pt disk electrode or an Au electrode of the quartz crystal resonator by potentiodynamic electropolymerization. Subsequently, the carnosine template was extracted from the MIPs with 0.1 M NaOH, as confirmed by the differential pulse voltammetry (DPV), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy measurements. For carnosine sensing, impedimetric capacity (IC) measurements were performed under flow-injection analysis (FIA) conditions resulting in the limit of detection of 20 μM (at S/N = 3). This limit implied the readiness of the chemosensor for carnosine determination in clinical samples. Due to multiple modes of carnosine binding to MIP recognition sites, the IC chemosensor was found to be more selective to carnosine than to its common interferences including anserine, carcinine and histidine. Advantageously, the imprinting factor, determined by piezoelectric microgravimetry (PM), was high equaling 14.9.

CRISPR/Cas9 is a powerful gene-editing tool allowing for specific gene manipulation at targeted sites in the genome. Here, we used CRISPR/Cas9-mediated gene editing to introduce single amino acid mutations into proteins involved in T cell receptor signalling pathways. Knock-in mutations were introduced in Jurkat T cells by homologous directed repair using single-stranded oligodeoxynucleotides. Specifically, we aimed to create targeted mutations at two loci within LCK, a constitutively expressed gene, and at three loci within SH2D2A, whose expression is induced upon T cell activation. Here, we present a simple workflow that can be applied by any laboratory equipped for cell culture work, utilizing basic flow cytometry, Western blotting and PCR techniques. Our data reveal that gene editing may be locus-dependent and can vary between target sites, also within a gene. In our two targeted genes, on average 2% of the clones harboured homozygous mutations as assessed by allele-specific PCR and subsequent sequencing. We highlight the importance of decreasing the clonal heterogeneity and developing robust screening methods to accurately select for correct knock-in mutations. Our workflow may be employed in other immune cell lines and acts as a useful approach for decoding functional mechanisms of proteins of interest.

This paper presents a detailed characterization of Ti surface geometries as produced by non-contact laser functionalization and its impact on the process of protein adsorption. The proposed surface modification is designed for the local treatment of implantable devices with original roughness. In this work, titanium plates were initially modified by the two most common mechano-chemical treatments, shot peening and acid etching. The material under study was next functionalized DLIL (Direct Laser Interference Lithography) in order to obtained two different surface patterns: grooves and islands. The modified surfaces were characterized in terms of their shape, roughness, wettability, surface energy and chemical composition. For this purpose, the following methods were used: scanning electron microscopy, optical profilometry, atomic force microscopy, contact angle measurements, and X-ray photoelectron spectroscopy. Protein adsorption tests were conducted to consider the potential of the proposed methodology in biomedical applications and to compare the influence of the two different surface patterns on the initial state of ossointegration. To this end, XPS and FTIR studies were conducted. The systematic analysis presented will be useful when selecting an appropriate surface geometry for the local surface functionalization of implantable devices.

Nanostructured artificial receptor materials with unprecedented hierarchical structure for determination of human serum albumin (HSA) are designed and fabricated. For that purpose a new hierarchical template is prepared. This template allowed for simultaneous structural control of the deposited molecularly imprinted polymer (MIP) film on three length scales. A colloidal crystal templating with optimized electrochemical polymerization of 2,3′-bithiophene enables deposition of an MIP film in the form of an inverse opal. Thickness of the deposited polymer film is precisely controlled with the number of current oscillations during potentiostatic deposition of the imprinted poly(2,3′-bithiophene) film. Prior immobilization of HSA on the colloidal crystal allows formation of molecularly imprinted cavities exclusively on the internal surface of the pores. Furthermore, all binding sites are located on the surface of the imprinted cavities at locations corresponding to positions of functional groups present on the surface of HSA molecules due to prior derivatization of HSA molecules with appropriate functional monomers. This synergistic strategy results in a material with superior recognition performance. Integration of the MIP film as a recognition unit with a sensitive extended-gate field-effect transistor (EG-FET) transducer leads to highly selective HSA determination in the femtomolar concentration range.

A new redox conducting polymer, viz. poly[meso-N,N′-bis(salicylidene)-2,3-butanediaminonickel(II)], poly[meso-Ni(II)-SaldMe], belonging to the Schiff base polymer family, was electrochemically synthesized. The charge transfer and polymerization mechanism were unraveled by simultaneous cyclic voltammetry (CV) and in situ UV–vis, FTIR-ATR, and ex situ low-temperature ESR spectroscopy. With the latter, a short-living paramagnetic transient form of electro-oxidized poly[meso-Ni(II)-SaldMe] was detected. This form was identified as the bisphenolic radical cation. In situ UV–vis and FTIR-ATR spectroelectrochemistry measurements revealed that the charge transfer of the polymer involved bisphenolic radical cation formation at the potential lower than 0.80 V vs Ag/Ag+ and then dication formation at the potential exceeding 0.80 V. The proposed mechanism of electropolymerization of meso-N,N′-bis(salicylidene)-2,3-butanediaminonickel(II), meso-Ni(II)-SaldMe, involves two steps. First, electro-oxidation of the monomer...

Surfaces of iron oxide of ferrimagnetic magnetite (Fe3O4) nanoparticles (MNPs) prepared by Massart's method and their functionalized form (f-MNPs) with succinic acid, L-arginine, oxalic acid, citric acid, and glutamic acid were studied by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR-S), UV-vis, thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), and reflection electron energy loss spectroscopy (REELS). The XPS analysis of elements and their chemical states at the surface of MNPs and f-MNPs revealed differences in chemical bonding of atoms, content of carbon-oxygen groups, iron oxide forms, iron oxide magnetic properties, adsorbed molecules, surface coverage, and overlayer thickness, whereas the Auger parameters (derived from XPS and Auger spectra) and elastic and inelastic scattering probabilities of electrons on atoms and valence band electrons (derived from REELS spectra) indicated modification of surface charge redistribution, electronic, and optical properties. These modified properties of f-MNPs influenced their biological properties. The surfaces biocompatible for L929 cells showed various cytotoxicity for HeLa cells (10.8-5.3% of cell death), the highest for MNPs functionalized with oxalic acid. The samples exhibiting the largest efficiency possessed smaller surface coverage and thickness of adsorbed molecules layers, the highest content of oxygen and carbon-oxygen functionalizing groups, the highest ratio of lattice O2- and OH- to C sp2 hybridizations on MNP surface, the highest ratio of adsorbed O- and OH- to C sp2 hybridizations on adsorbed molecule layers, the closest electronic and optical properties to Fe3O4, and the lowest degree of admolecule polymerization. This high cytotoxicity was attributed to interaction of cells with a surface, where increased content of oxygen groups, adsorbed O-, and OH- may play the role of additional adsorption and catalytic sites and a large content of adsorbed molecule layers of carboxylic groups facilitating Fenton reaction kinetics leading to cell damage.

A molecularly imprinted polymer (MIP) recognition system was devised for selective determination of an immunogenic gluten octamer epitope, PQQPFPQQ. For that, a thin MIP film was devised, guided by density functional theory calculations, and then synthesized to become the chemosensor recognition unit. Bis(bithiophene)-based cross-linking and functional monomers were used for this synthesis. An extended-gate field-effect transistor (EG-FET) was used as the transduction unit. The EG-FET gate surface was coated with the PQQPFPQQ-templated MIP film, by electropolymerization, to result in a complete chemosensor. X-ray photoelectron spectroscopy analysis confirmed the presence of the PQQPFPQQ epitope, and its removal from the MIP film. The chemosensor selectively discriminated between the octamer analyte and another peptide of the same number of amino acids but with two of them mismatched (PQQQFPPQ). The chemosensor was validated with respect to both the PQQPFPQQ analyte and a real gluten extract from semolina flour. It was capable to determine PQQPFPQQ in the concentration range of 0.5-45 ppm with the limit of detection (LOD) = 0.11 ppm. Moreover, it was capable of determining gluten in real samples in the concentration range of 4-25 ppm with LOD = 4 ppm, which is a value sufficient for discriminating between gluten-free and non-gluten-free food products. The gluten content in semolina flour determined with the chemosensor well correlated with that determined with a commercial ELISA gluten kit. The Langmuir, Freundlich, and Langmuir-Freundlich isotherms were fitted to the epitope sorption data. The sorption parameters determined from these isotherms indicated that the imprinted cavities were quite homogeneous and that the epitope analyte was chemisorbed in them.

We demonstrate that a new, stable, artificial TATA (T — thymine, A — adenine) box is recognized by amino acids recognizing the natural TATA box. Here, the former mimicked, as a minimal motif, oligodeoxyribonucleotide interactions with amino acids of proteins involved in repairing of damaged dsDNA. By electropolymerization, we molecularly imprinted non-labeled 5′-TATAAA-3′ via Watson-Crick nucleobase pairing, thus synthesizing, in a one-step procedure, the hexakis[bis(2,2′-bithien-5-yl)] TTTATA and simultaneously hybridizing it with the 5′-TATAAA-3′ template. That is, a stable dsDNA analog having a controlled sequence of nucleobases was formed in the molecularly imprinted polymer (MIP). The 5′-TATAAA-3′ was by the X-ray photoelectron spectroscopy (XPS) depth profiling found to be homogeneously distributed both in the bulk of the MIP film and on its surface. The 5′-TATAAA-3′ concentration in the 2.8(±0.2)-nm relative surface area, ~140-nm thick MIP film was 2.1 mM. The MIP served as a matrix of an artificial TATA box with the TATAAA-promoter sequence. We comprehensively characterized this artificial DNA hybrid by the polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and X-ray photoelectron spectroscopy (XPS). Further, we examined interactions of DNA repairing TATA binding protein (TBP) amino acids with the artificial TATA box prepared. That is, molecules of l -phenylalanine aromatic amino acid were presumably engaged in stacking interactions with nucleobase steps of this artificial TATA box. The nitrogen-to‑phosphorus atomic % ratio on the surface of the MIP-(5′-TATAAA-3′) film increased by ~1.6 times after film immersing in the l -glutamic acid solution, as determined using the XPS depth profiling. Furthermore, l -lysine and l -serine preferentially interacted with the phosphate moiety of 5′-TATAAA-3′. We monitored amino acids interactions with the artificial TATA box using real-time piezoelectric microgravimetry at a quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) spectroscopy under flow injection analysis (FIA) conditions.

New thiophene-carbazole functional and cross-linking monomers electropolymerizing at potentials sufficiently low for molecular imprinting of an electroactive aripiprazole antipsychotic drug were herein designed and synthesized. Numerous conducting molecularly imprinted polymer (MIP) films are deposited by electropolymerization at relatively low potentials by electro-oxidation of pyrrole, aniline, phenol, or 3,4-ethylenedioxythiophene (EDOT). However, their interactions with templates are not sufficiently strong. Hence, it is necessary to introduce additional recognizing sites in these cavities to increase their affinity to the target molecules. For that, functional monomers derivatized with substituents forming stable complexes with the templates are used. However, oxidation potentials of these derivatives are often, disadvantageously, higher than that of parent monomers. Therefore, we designed and synthesized new functional and cross-linking monomers, which are oxidized at sufficiently low potentials. The deposited MIP and non-imprinted polymer (NIP) films were characterized by PM-IRRAS and UV–vis spectroscopy and imaged with AFM. The structure of the aripiprazole pre-polymerization complex with functional monomers was optimized with density functional theory (DFT), and aripiprazole interactions with imprinted cavities were simulated with molecular mechanics (MM) and molecular dynamics (MD). MIP-aripiprazole film-coated electrodes were used as extended gates for selective determination of aripiprazole with the extended-gate field-effect transistor (EG-FET) chemosensor. The linear dynamic concentration range was 30–300 pM, and the limit of detection was 22 fM. An apparent imprinting factor of the MIP-1 was IF = 4.95. The devised chemosensor was highly selective to glucose, urea, and creatinine interferences. The chemosensor was successfully applied for aripiprazole determination in human plasma. The results obtained were compared to those of the validated HPLC-MS method.

Molecularly imprinted polymers (MIPs) have been widely studied for sensing and separation of compounds selectively. These artificial biomimicking recognition units are highly sensitive and selective to target analytes. Electrochemical preparation of MIPs offers advantages including ease of preparation as well as control over the polymer nucleation and growth, thickness, and film morphology. Moreover, it is possible to follow the formation of cavities electrochemically through the gate effect. Few reports have focussed on selective catalysis by using MIPs. However, the application of these MIPs in the field of electrocatalysis remains unexplored and, therefore, there is a large research scope in this domain. Biphenols are structural motifs of several molecules in nature and for many drugs. They are efficient ligands for catalytic systems and are highly stable under electrochemical condition. In particular, 3,3,5,5-tetramethyl-2,2-biphenol acts as a significant backbone in phosphorus-based ligand systems for calatysis. The oxidation of 2,4-dimethylphenol yields several different products including polycyclic compounds formed by C-H bond activation (Scheme 1). Therefore, designing a scalable process, in which the desired biphenol is selectively produced, is challenging. In the present work, we aim to develop MIPs that can be applied for selective electrosynthesis of the desired C-C coupled biphenol through electro-oxidation of the corresponding phenol. For this purpose, the functional monomer was selected based on the Gibbs free energy of its interaction with the target biphenol template in density functional theory (DFT) simulations. Complexation of the functional monomer with the template was confirmed by spectroscopic titrations. Electroactive monomers can polymerize to form either conducting or nonconducting polymers. In our system, a conductive MIP film was prepared using derivatized thiophene functional monomers. Then, the template extraction process was optimized. Electro-oxidation of 2,4-dimethyl phenol was studied in detail to reach as high yield as possible of the desired biphenol product at a bare platinum electrode. HPLC-MS was used to identify the substrate and products of the electrosynthesis. Then, selectivity of the electrosynthesis study was performed for the MIP film-coated electrode in comparison to a non-imprinted polymer (NIP) film-coated electrode, and a bare electrode. Figure 1

A 3-D molecularly imprinted polymer (MIP) film comprising a unit for recognition of 2,4,6-trinitrophenol (TNP) embedded with a fluorophore for signal transduction and quantification is newly fabricated and shown to be selective and sensitive to the target TNP analyte in solution. The limit of detection of this chemosensor reached a level of subnanogram per liter of TNP concentration. Moreover, this MIP film was fabricated by just one-step electropolymerization from a prepolymerization solution; therefore, the procedure is readily extendable for selective determination of other nitroaromatic explosives.

In this work analysis of thermal behavior of piezoresistive silicon Scanning Thermal Microscopy cantilever with integrated resistive metal tip is presented. In order to determine the temperature distribution of the tip in the case of present power supply micro-Raman spectroscopy was used. Two different excitation wavelengths, in particular from visible and ultraviolet spectral ranges, were applied. The application of different excitation wavelengths results in significantly different penetration depth of the light into the silicon. As a result the information from different depths of the material is detected. The results obtained from micro-Raman spectroscopy can be summarized in two points. First: the increase of the temperature is observed only in the vicinity of conducting tracks. This increase is of the order of 10K. Second: there is no large increase of the temperature in the thin layer of silicon substrate in the vicinity of silicon/silicon dioxide interface. Measured temperature distribution is compared with theoretical simulation calculated with Finite-Element Method and data obtained from thermal imaging. Calculated thermal effect can be summarized as follows: the temperature increases by 11K for conducting track, and by 9K for silicon in the vicinity of the track above the temperature of the environment. The increase of the temperature of the cantilever obtained from thermal imaging is equal to about 12K. Display Omitted Temperature distribution in new type of cantilever for SThM was investigated.All applied methods present the same results within their accuracies.Application of two excitation wavelengths allowed investigation of thermal effect for two different depths.Agreement between experimental techniques and theoretical calculations allowed to validate FEM models in microscale.

This study proposes Direct Laser Interference Lithography as a highly suitable technique for functionalization titanium surfaces for biomedical applications. DLIL was employed to produce periodic patterns on titanium after two commonly used surface treatments of implantable devices (shot peening and acid etching). The biomedical potential of the proposed method was analyzed using immersion tests in a simulated body fluid solution and cell adhesion tests. After 48 h of immersion surface morphology, the chemical composition and phase structure of the apatite layers deposited on the modified titanium were analyzed. In order to analyze the kinetics of the apatite layer growth, X-Ray Photoelectron Spectroscopy measurements at different soaking times were performed. Cell adhesion tests were performed using human fetal osteoblastic cells (hFOB). The adhered cells were analyzed using confocal and scanning electron microscopies after 48 h of incubation. The formation of biomimetic apatite layers was accelerated on the titanium surface structures after DLIL modification. The periodic titanium patterns induced more uniform and direct cell growth. This effect is mainly connected with the surface properties of the DLIL-modified substrates. The formation mechanism of biomimetic apatite on the textured titanium samples, as well as the compounds created on the surface, are discussed.

Herein, we report an electrochemically initiated co-polymerization of two electroactive monomers of different oxidation potentials. The molar ratio of low oxidation potential monomer in the solution for electropolymerization was optimized to find condition suitable for co-polymerization of high-oxidation potential monomer effectively at lower oxidation potential. The XPS analysis confirmed successful co-polymerization. This co-polymerization condition was further used in imprinting of melatonin, an electroactive compound. Entrapment of melatonin in the polymer matrix was confirmed by measuring electroactivity of melatonin in the 0.1 M KCl−HCl solution (pH 1.6). This MIP based electrochemical sensor determined melatonin in the linear dynamic concentration range 10–80 μM. Detectability of proposed chemosensor was 0.14 μM (S/N = 3). The mean RSD for the concentration range studied was ∼20%. Selectivity of the chemosensor was satisfactory towards common structural analogues and biomolecules. Furthermore, the chemosensor was successfully used to determine melatonin in real samples. The sensitivity in the presence of matrix components and that for the KCl−HCl solution were quite similar. The results obtained indicate the suitability of the devised chemosensor for practical applications.

Protein imprinting is challenging mainly because of their large molecular size. It is very difficult [...]

This paper describes the effects of phosphorus implantation into n-type 4H-SiC substrate prior to standard dry oxidation process. Phosphorus incorporation has been reported to be one of the most efficient means of increasing SiC MOSFET field mobility however the physical basis of this phenomenon is still not clear. The aim of this research is to investigate the influence of phosphorus implantation on trap density profile close to conduction band of silicon carbide and to gain understanding of physical processes responsible for observed trap density improvement in phosphorus related oxidation technologies of silicon carbide.

By means of molecular imprinting of a conducting polymer, molecular cavities selective for oxytocin nonapeptide, an autism biomarker, were designed. Embedding of the oxytocin template, and then its extracting from the molecularly imprinted polymer (MIP) was confirmed by the XPS analysis. AFM imaging of the MIP film surface indicated changes in mechanical properties of the film after template extraction. The MIP synthetic receptor was deposited by potentiodynamic electropolymerization as a thin film on an Au film electrode in an electrochemical miniaturized microfluidic cell. The use of this cell allowed to shorten analysis time and to decrease the sample volume. The linear dynamic concentration range extended from 0.06 to 1mM with the limit of detection of 60µM (S/N = 3). Advantageously, sensitivity of the diagnostic microfluidic platform devised for oxytocin determination in both synthetic serum samples and in aqueous solutions was similar and, moreover, it was selective to common interferences, such as oxytocin analogs and potential metabolites.

The paper reports on the fabrication of electrical isolation for planar AlGaN/GaN high electron mobility transistor using Al double-implantation. The implantation was performed using Al+ ions with energies of 800 keV and 300 keV with doses of 1.5×1013 ion/cm2 and 1×1013 ion/cm2, respectively. Electrical measurements have shown that after implantation the sheet resistance was 1.8×1011 Ω/□ and increased to 1.17×1014 Ω/□ and 3.29×1012 Ω/□ after annealing at 400°C and 600°C respectively. Annealing at 800°C decreased the sheet resistance to 1.38×108 Ω/□. Characterization by XRD, Raman and photoluminescence spectroscopy give evidence that implantation damages the crystal lattice, yielding insulating properties. It has been demonstrated that the isolation is stable up to 600°C.

The 3C-SiC silicon carbide is a promising substrate material for MOS transistors. Parameters of MOS transistors are strongly dependent on the processing of the semiconductor-dielectric system. We study and compare the crucial features of the SiC(3C)-SiO2 systems with thermally grown and PECVD deposited SiO2 layers. For both types of systems, using the Al-SiO2-SiC(3C) capacitors as test structures, we determine and compare the following properties: The leakage currents and breakdown voltages of SiO2 layers, densities and distributions in energy of interface traps, band diagrams of the SiC(3C)-SiO2 systems, as well as structural properties and mechanical stresses in both types of SiO2 layers. Characterization of the above mentioned features is done using electrical, photoelectric and optical methods, including micro-Raman spectroscopy. The characterization results lead us to the conclusion, that PECVD deposition of SiO2 followed by wet oxygen annealing is more advantageous for MOSFET fabrication than the thermal growth of the SiO2 layer.

The structure of carbonic layer in three samples composed of 4H polytype of silicon carbide and the following sequence of layers: carbon/nickel/silicon/nickel/silicon was investigated with Raman spectroscopy. Different thermal treatment of the samples led to differences in the structure of carbonic layer. Raman measurements were performed with visible excitation focused on two interfaces: silicon carbide/carbon and carbon/silicide. The results showed differences in the structure across carbon film although its thickness corresponds to 8/10 graphene layers.

In this article, an influence of nitrogen implantation dosage on SiC MOS structure is analyzed using wide range of nitrogen implantation dose (between ~1013 – 1016). Authors analyzed electrical and material properties of investigated samples using C-V, I-V measurements, Raman spectroscopy, and XPS profiling. It has been shown that surface state trap density is directly connected to implantation damage and thus implantation conditions. Using research results a trap origin at given energy can be concluded.

2,5-bis(2-benzoxazolyl)-1,4-dimethoxybenzene (BBDB) and its symmetrically deuterated isotopomer (BBDB-d2) were studied in supersonic jets. The laser induced fluorescence excitation (LIF(E)) spectra of both compounds made possible the unequivocal identification of the spectral origins belonging to four isotopologues differing only in the orientation of the C–H/C–D bonds of the methyl groups with respect to the molecular plane. The splitting parameters of the origin (−1.1 cm−1, −0.35 cm−1, 0.3 cm−1) as well as the LIF(E) spectra of both isotopomers were satisfactorily reproduced by DFT and TD-DFT calculations.

Three samples of 4H polytype of silicon carbide (4H-SiC) covered with the following sequence of layers: carbon/nickel/silicon/nickel/silicon were investigated with micro-Raman spectroscopy. Different thermal treatments of each sample result in differences of carbon layer structure and migration of carbon atoms thorough silicide layer. Two ranges of Raman shift were investigated. The first one is placed between 1000 cm−1 and 2000 cm−1. The main carbon bands D and G are observed in this range. Analysis of the positions of these bands and their intensity ratio enables one to determine the graphitization degree of carbon layer. Additional information about the changes of the carbon layer structure was derived from analysis of 2D band placed around 2700 cm−1. Application of deep ultraviolet excitation delivered information about the structure of carbon layer formed on the free surface of silicides and the distribution of the carbon inside the silicide layer.

This paper presents the description of triplet-triplet annihilation in the case of nondominant first-order decay of molecules in the triplet state. The kinetics of the statistical system is influenced by joined action of two processes: the first- and second-order decies. This kinetics can be described with analytical function if the rate parameter of second-order reaction is constant. The approach presented here combines the well-known Smoluchowski formula with the previously published intuitive and non-Fickian models of diffusion-controlled triplet-triplet annihilation. The kinetics of the delayed fluorescence of anthracene is used as a practical example of applicability of the model proposed. The advantages and limits of the proposed model are discussed.

Silicon carbide (SiC) is a wide band gap semiconductor having good thermal conductivity and high break down voltage. Formation of SiO2layer in thermal oxidation process completes the set of properties of SiC as a promising material for fabrication of high power and high frequency electronic devices. This picture is perturbed by Near Interface Traps (NIT's) that decrease the surface mobility of charge carriers. The origin of NIT's is still the subject of discussion and there are several candidates for NIT's. One possibility is the formation of carbonic structures during the process of manufacturing of MOS-type structures. The aim of this work was to look for possible carbonic inclusions with Raman spectroscopy. The attention of authors was focused on non-destructive way of application of the experimental technique.

Silicon carbide (SiC) is a wide band gap semiconductor suitable for high power and frequency electronic devices. The most important features of the material making it promising in this application are good thermal conductivity, high breakdown voltage and formation of native SiO 2 layer on the surface of SiC substrate by thermal oxidation. However, the material has significant drawbacks. The most important one is low surface mobility. The surface mobility of the charge carriers is decreased by near interface states (NIT's — Near Interface Traps) — caused by defects formed in the vicinity of SiC/SiO 2 interface. There are several candidates for NIT's and one of them is the occurrence of carbonic structures. Raman spectroscopy provides information about investigated structure without destruction of the sample. The aim of this work was to look for carbonic inclusions in 4H and 3C polytypes of SiC. The attention was focused on this part of the range of the Raman Shift where the strongest bands of carbonic structures are expected.

Jet-cooled terrylene has been studied in helium buffer gas using a pulsed nozzle by means of laser-induced fluorescence. Fluorescence excitation and two-color depletion experiments (resulting in hole burning spectra) are presented. Analysis of the spectra leads to the conclusion that another excited electronic state is present in the vicinity of the allowed 1B1u state. Assuming (according to previous literature suggestions Karabunarliev, S.; Baumgarten, M.; Müllen, K. J. Phys. Chem. A 1998, 102, 7029) that this dark state is the 21Ag state, we discuss the vibrational structure of the fluorescence excitation spectrum in terms of two manifolds of vibronic states belonging to Sd(21Ag) and S1(1B1u) states. The anomalous shift between excitation and dispersed fluorescence spectra observed earlier for terrylene in a neon matrix is discussed as a consequence of terrylene electronic relaxation to the low-energy dark state.

We devised and prepared a conducting molecularly imprinted polymer (MIP) for human serum albumin (HSA) determination using semi-covalent imprinting. The bis(2,2'-bithien-5-yl)methane units constituted the MIP backbone. This MIP was deposited as a thin film on an Au electrode by oxidative potentiodynamic electropolymerization to fabricate an electrochemical chemosensor. The HSA template imprinting, and then its releasing from the MIP was confirmed by the differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), XPS, and PM-IRRAS measurements as well as by AFM imaging. Semi-covalent imprinting provided a very well defined locations of recognition sites in the MIP molecular cavities. These sites populated the imprinted cavities or the MIP surface only. The DPV and EIS response of the MIP film coated electrode to the HSA analyte was linear in the range of 0.8 to 20 and 4 to 80 µg/mL HSA, respectively, with the limit of detection of 16.6 and 800 ng/mL, respectively. The impressively high imprinting factor reached, exceeding 20, strongly confirmed that semi-covalent imprinting resulted in formation of a large number of very well defined molecular cavities with high affinity to the HSA molecules. The MIP selectivity against low-(molecular weight) interferences, common for physiological fluids, such as blood and urea, was very high. There was no response to the presence of these interferences at concentrations encountered in the samples analyzed. Moreover, the chemosensor selectivity to the myoglobin and cytochrome c interferences was excellent while that to lysozyme was slightly lower but still high. The chemosensor was useful for determination of abnormal HSA concentration in a control blood serum.

Summary Simple synthetic procedure (reactions between iridium trichloride hydrate with a series of fluorine substituted 2-phenyl-N-methyl-benzimidazole derivatives L) leads to the cyclometallated Ir(III) complexes IrL2(acac) and IrL2(pic) where acac = acetylacetonate and pic = α-picolinate anions, respectively. All the investigated complexes exhibit strong absorption in the UV region, due to the spin allowed intra-ligand (IL) transitions, and moderately intense bands in the visible region, due to the metal-to-ligand-charge-transfer (MLCT) transitions. The complexes exhibit also strong luminescence in the deoxygenated 1:1 acetonitrile/dioxane solutions at 298 K as well as in the butyronitrile glasses at 77 K. In both experimental conditions the structured emissions (with the 0–0 transition within the 480–510 nm range of UV-Vis radiation) have been observed. Cyclic voltammetry investigations point out to reversible character of the electrochemical reactions leading to stable IrL2(acac)+ or IrL2(pic)+ cations and IrL2(pic)− anions. The corresponding IrL2(acac)− species have been found to be unstable under the applied experimental conditions (1:1 acetonitrile/dioxane solutions containing 0.1 M (C4H9)4NPF6 as the supporting electrolyte) most probably due to the irreversible electrochemical reduction of the acac− ligand. Appropriate combination of the electrochemical and luminescence properties found for the investigated complexes allows for the electron transfer generation of the excited 3∗IrL2(pic) and 3∗IrL2(acac) species. Triple-potential-step technique was used to create electrochemiluminescence (ECL) emission by annihilation of the electrochemically generated IrL2(acac)+ or IrL2(pic)+ cations and 4,4’-dicyano-biphenyl radical anion. Very high ECL emission efficiencies (close to the excited 3∗IrL2(acac) and 3∗IrL2(pic) luminescence yields) have been found.

Electrogenerated chemiluminescence (ECL) studies have been performed for the iridium(III) cyclometalated L2Ir(acac) complexes in 0.1 M (n-C4H9)4NPF6 acetonitrile–dioxane (1:1, v,v) solutions using a triple-potential-step technique. Electron transfer between electrochemically generated L2Ir(acac)+ cations and A− (radical anions of aromatic nitriles) leads to generation of the excited 3*L2Ir(acac) species. Extremely high ECL efficiencies (up to 0.55) close to the excited 3*L2Ir(acac) luminescence yields have been found.

The validity of Smoluchowski's theory is demonstrated by its application to the bimolecular triplet–triplet annihilation (TTA) T1 + T1 → S0 + S1 in viscous solution. For that purpose the delayed S1 → S0 fluorescence of anthracene in cis-1,3-dimethylcyclohexane/trans-1,4-dimethylcyclohexane (1∶1) was measured after UV excitation with long laser pulses (∼30 μs) in a temperature range where TTA is completely diffusion controlled. Through the adequate treatment of the kinetics of TTA upon spatially homogeneous and spatially periodic excitation (which is partially based on the results of previous publications) absolute values for the diffusion coefficients D of triplet molecules, for the effective annihilation distance RA and for the Forster radius RST of heterogeneous annihilation S1 + T1 → S0 + Tn were determined. The temperature dependence of all three parameters (D, RA and RST) is discussed. From the decrease of RA with increasing temperature, the parameters A and L can be determined, which define the exponential distance dependence of the annihilation of a triplet pair in the kinetic model of Butler and Pilling (1977). Differences of the two models and applicability criteria are discussed.

Six new compounds, derivatives of [2,2′-bipyridyl]-3,3′-diol (BP(OH) 2 ) are recommended as useful modifications of the parent structure. One group, three molecules with conjugate aromatic substituents (6-methyl-6′-styryl-BP(OH) 2 , 6-(4-methoxystyryl)-6′-methyl-BP(OH) 2 , 6-methyl-6′-(4-phenylstyryl)-BP(OH) 2 ), are potential solar energy concentrators — they have absorption spectra red shifted with respect to BP(OH) 2 . To the second group belong the derivatives with the aliphatic side chains, better “accepted” by polyethylene than the parent molecule. These compounds are designed to improve their function as photostabilizers of polymers. All six new compounds were synthesized and their photophysical characteristics were studied. Absorption spectra, phototautomeric fluorescences and their excitation spectra, as well as quantum yields and lifetimes are reported.

The diheptyl-bipyridyl-diol, as a non-self-absorbing fluorescent compound characterized by a large separation between absorption and fluorescence bands, has been incorporated in polyvinyl-butyral film. Steady state luminescence and lifetime were measured. An increase of luminescence intensity by about 34% in the presence of silver nanoparticles was observed. No appreciable changes were found in the corresponding lifetimes. The system is proposed as a potential candidate for increasing the LSC efficiency.

The nature of the lowest triplet state of the donor–acceptor N-phenylphenothiazine derivatives has been studied by means of phosphorescence and EPR spectroscopy in various low temperature glasses. The triplet excitation of N-phenylphenothiazine and N-(p-anisyl)-phenothiazine is localised within the phenothiazine subunit. On the contrary, the 77 K phosphorescence of the molecules containing an electron acceptor group (i.e. –CN, –COCH3 or –COC6H5 at the 4′ position) is similar to that for benzonitrile, acetophenone or benzophenone, respectively, although the energy levels of their T1 states are higher than that of phenothiazine. With increasing temperature, however, their phosphorescence becomes similar to that characteristic for phenothiazine. This finding has been explained in terms of the excited-state intramolecular energy transfer accompanied by the planarisation of the phenothiazine kernel. The results of crystallographic investigations support this hypothesis.

For a few carbazole-related compounds in alcoholic solution, photoinduced solute−solvent proton-transfer dynamics are studied by means of femto- and picosecond fluorescence transient measurements. ...

Radiative and nonradiative electron transfer (exemplified by the CT fluorescence and nonradiative charge recombination process in the singlet manifold, respectively) in a series of donor–acceptor phenoxazine and phenothiazine derivatives is reported. An analysis of the CT fluorescence leads to the quantities relevant for the radiative electron transfer in the Marcus inverted region. Using a nonadiabatic theory of electron transfer and the latter parameters, the rate constants for nonradiative electron transfer can be predicted. Electronic coupling elements V0 between the 1 CT state and the ground state obtained from the radiative rates are in agreement with those calculated from the simple LCAO MO model which assumes that V0 are mainly determined by the interactions between the atoms forming the A–D bond.

Solvent-dependent electronic structure of the selected donor (D)–acceptor (A) derivatives of 5-methylindole and 5-methoxyindole containing benzonitrile as an electron acceptor in the fluorescent charge transfer (CT) states has been investigated. The mechanism of the radiative charge recombination 1 CT → S 0 is discussed in terms of the Mulliken–Murrell model of the CT complexes and the Marcus theory of photoinduced electron transfer (ET). Solvatochromic effects on the spectral position and profile of the stationary fluorescence spectra point to a considerable CT character of the emitting singlet states of all the compounds studied. The determination of the electronic transition dipole moments corresponding to the 1 CT → S 0 fluorescence and the band-shape analysis of the corresponding spectra leads to the quantities relevant for the charge recombination in the Marcus inverted region. It is shown that some of the photophysical properties of the compounds can be predicted in terms of a simple model from the properties of individual chromophores.

Vibrational structure of four molecules known to undergo an extremely rapid excited state proton transfer: [2,2′-bipyridyl]-3,3′-diol, 5,5′-dimethyl[2,2′-bipyridyl]-3,3′-diol, [2,2′-bipyridyl]-3-ol and 2-(2-pyridyl)phenol was studied with FTIR and Raman spectroscopy and ab initio quantum chemical calculations. The assignments for all the observed vibrations lying below 600 cm−1 were proposed, based on the comparison of experimental and computational results of transition energies, shifts upon deuterium and methyl substitution, and the analysis of the evolution of individual bands along the series. The calculations appear to be very reliable in predicting the vibrational frequencies, and in reproducing frequency shifts resulting from deuteration and methylation. The assignment of low-frequency modes may be helpful in understanding of the phototautomerization mechanism, as well as in interpretation of the complicated structure of the band corresponding to the OH stretching vibration.

We focus our attention to the laser-controlled association process of poly(N-vinylcarbazole) by “pure” photon pressure effect. A few wt % N,N-dimethylformamide solution of the polymer was irradiated with a focused 1064 nm laser beam of sub wattage power, and a resultant condensation (microparticle formation) at a focal point of the microscope was initially probed by backscattering of He−Ne laser and later observed by transmission image of the microscope. To understand in detail the behavior of the polymer induced by the photon force, the relation between laser power and particle diameter, as well as repeated irradiation effect, were investigated. The laser-controlled association was successfully demonstrated even for short polymer chains of about 20 mean degrees of polymerization. Fluorescence spectra and their rise and decay curves were measured microspectroscopically for a formed microparticle. The results are different from those of the polymer in solution, suggesting the association structure is chara...

Influence of intermolecular hydrogen bonding upon the vibrational pattern in the low-frequency region was studied for 2-(2-hydroxyphenyl)-3-pyridynol—a molecule which reveals both intra and intermolecular hydrogen bonds in the crystal phase. Combined use of IR and Raman spectroscopy and ab initio 6-31G∗∗ calculations for the isolated and water-complexed compound made it possible to find low frequency transitions corresponding to the vibrations of the water solvate.

We report on (sub)picosecond fluorescence studies of the mono- to diketo tautomer reaction in photo-excited [2,2′-bipyridyl]-3,3′-diol in aprotic and protic solvents. In aprotic solvents no influence of the nature of the solvent, temperature and deuteration of the hydroxyl groups on the proton transfer dynamics was found. In protic solvents, however, the proton transfer time is found to change proportionally with the viscosity coefficient of the solvent. We briefly discuss (i) the formation of the mono- and diketo forms from the dienol form and (ii) the nature of the vibrational modes assisting in the proton transfer process.