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In this study, scaffolds were prepared via an electrospinning method for application in oral cavities. The hydrophilicity of the fiber mesh is of paramount importance, as it promotes cell spreading; however, the most commonly used polyvinyl alcohol (PVA) and other hydrophilic fiber meshes immediately disintegrate in aqueous media. In contrast, the excessive hydrophobicity of the scaffolds already inhibits cells adhesion on the surface. Therefore, the hydrophilicity of the fiber meshes needed to be optimized. Scaffolds with different polyvinyl alcohol (PVA)/chitosan/citric acid ratios were prepared. The addition of chitosan and the heat initiated cross-linkage of the polymers via citric acid enhanced the scaffolds’ hydrophobicity. The optimization of this property could be followed by contact angle measurements, and the increased number of cross-linkages were also supported by IR spectroscopy results. The fibers’ physical parameters were monitored via low-vacuum scanning electron microscopy (SEM) and atomic force microscopy (AFM). As biocompatibility is essential for dental applications, Alamar Blue assay was used to prove that meshes do not have any negative effects on dental pulp stem cells. Our results showed that the optimization of the fiber nets was successful, as they will not disintegrate in intraoral cavities during dental applications.

In this study, metallic nanoislands were prepared by thermal annealing of gold thin film produced by vacuum evaporation on a glass substrate to investigate the surface-enhanced Raman scattering (SERS) effect on them. The influence of the analyte on the enhancement factor of SERS was studied with riboflavin and rhodamine 6G dye. Two laser excitation sources at 532 and 633 nm wavelengths were used for SERS measurements. We found that the enhancement factors of the gold nanoisland SERS substrates were influenced by the analytes’ adsorption tendency onto their surfaces. The SERS amplification was also found to be dependent on the electronic structure of the molecules; higher enhancement factors were obtained for rhodamine 6G with 532 nm excitation, while for riboflavin the 633 nm source performed better.

This paper presents a systematic study of the investigation of nanoparticle (NP) agglomerate films fabricated via depositing spark-generated Au, Ag, and Au/Ag NPs onto quartz microscope coverslips in a low-pressure inertial impactor. The primary focus of the study is to characterize these nanostructures and to examine their potential application in surface-enhanced Raman spectroscopy (SERS). The characterization of the produced nanostructures was carried out by performing optical absorbance measurements, morphology, and composition analysis, as well as testing the SERS performance of the NP films at three different excitation laser wavelengths in the visible range. The study aims to investigate the relationship between the optical properties, the morphology, and the enhancement of the produced samples at different excitations, and the results are presented and discussed. The study highlights the potential of using spark ablation and inertial impaction-based deposition as a method for producing nanoparticle films for SERS.

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Metal ions such as nickel have a strong binding affinity to amino acids and form metal complexes of different geometry. This complex formation is influenced by many factors among others the kind of reactants and their relative concentrations, pH, and its effect on the net charge of the amino acid molecule. In this work, the formation of the histidine‐nickel (II) complex in different conditions was examined by Raman spectroscopy. In addition to the experiments, density functional theory (DFT) calculations on histidine‐nickel complexes were performed in order to elucidate the complex formation mechanism and optimal geometry of the structures as well as to investigate their vibrational properties. The Raman measurements showed double peaks at 1272 and 1297 cm−1, and triple peaks at 1322, 1336, and 1355 cm−1 that belong to the metal complex. The geometry optimizations and total energy calculations of His‐Ni (II) complex revealed that the octahedral geometry and the triplet spin state of Ni ion is the energetically favorable structure. This metal complex is formed through the nitrogen atom of the imidazole side chain, the nitrogen atom of the terminal amino group, and the oxygen atom of the carboxyl group. Experiments with pH revealed that the alkaline pH favors while the change of the concentration of the metal ions does not affect the the His‐Ni (II) complex formation.

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Gold and silver nanoparticles are widely used as signal amplification elements in various electrochemical and optical sensor applications. Although these NPs can be synthesized in several ways, perhaps one of the simplest methods of their preparation is the thermal annealing of pre-deposited thin metal films on glass. With this method, the parameters of the annealing process (time and temperature) and the pre-deposited thin film thickness influence and define the resulting size and distribution of the NPs on the surface. LSPR is a very sensitive optical phenomenon and can be utilized for a large variety of sensing purposes. SERS is an analytical method that can significantly increase the yield of the Raman scattering of target molecules adsorbed on the surface of metallic nanoparticles. In this work, the performance of Au/Ag nanoislands was investigated for SERS and LSPR applications. The nanoislands were generated by thermally annealing thin layers of silver and gold, which were previously sputtered onto glass surfaces. The sensitivity of LSPR and SERS-based devices were strongly dependent on the used material and the size and geometry of the metallic nanoparticles. By controlling these parameters, the plasmon absorption band can be tuned and the sensitivity can be optimized. This work was supported by the GINOP-2.3.2-15-2016-00041 project. ICs is grateful for the support of the János Bólyai Research Scholarship of the Hungarian Academy of Sciences.