Distinct advantages of surface enhanced Raman scattering (SERS) in molecular detection can benefit the enantioselective discrimination of specific molecular configurations. However, many of the recent methods still lack versatility and require customized anchors to chemically interact with the studied analyte. In this work, we propose the utilization of helicoid-shaped chiral gold nanoparticles arranged in an ordered array on a gold grating surface for enantioselective SERS recognition. This arrangement ensured a homogeneous distribution of chiral plasmonic hot spots and facilitated the enhancement of the SERS response of targeted analytes through plasmon coupling between gold helicoid multimers (formed in the grating valleys) and adjacent regions of the gold grating. Naproxen enantiomers (R(+) and S(-)) were employed as model compounds, revealing a clear dependence of their SERS response on the chirality of the gold helicoids. Additionally, propranolol and penicillamine enantiomers were used to validate the universality of the proposed approach. Finally, numerical simulations were conducted to elucidate the roles of intensified local electric field and optical helicity density on the SERS signal intensity and on the chirality of the nanoparticles and enantiomers. Unlike previously reported methods, our approach relies on the excitation of a chiral plasmonic near-field and its interaction with the chiral environment of analyte molecules, obviating the need for the enantioselective entrapment of targeted molecules. Moreover, our method is not limited to specific analyte classes and can be applied to a broad range of chiral molecules.

• Klíčová slova
• SERS, chiral gold nanoparticles, enantioselective detection, naproxen, plasmon coupling,
• Publikační typ
• časopisecké články MeSH

In this work, we proposed the functionalization of a surface plasmon-polariton (SPP)-supported gold grating surface with the metal-organic framework (MOF-5) for sensitive, selective and reproducible surface-enhanced Raman scattering (SERS) detection of organophosphorus pesticides. Homogeneous distribution of plasmon intensity along the Au grating surface ensures the high reproducibility of SERS results (deviation of Raman peak intensity does not exceed the 4% along the sample). The surface-assisted growth of thin MOF-5 film was accomplished in two steps procedure: (i) covalent grafting by 4-carboxyphenyl groups and (ii) the immersion of samples in the mother liquid of MOF-5. Proposed SERS chip proved itself to be a perfect analytical probe for the detection of organophosphorus pesticides with high reliability and low detection limit up to 10-12 M. Moreover, selective detection and recognition of several relevant organic contaminants (azo-dye, mycotoxin, and pesticide) from the simulated soil was successfully demonstrated. All SERS measurements were performed using portable Raman spectrometer and can easily be expanded to environmental conditions. Our work combines the high affinity of organic contaminants to the MOF-5 with excellent plasmonic excitation on the surface plasmon-polariton supported structure and shows the way to the realization of closed-to-ideal analytical SERS chip.

• Klíčová slova
• Gold grating, Metal-organic framework, Organophosphorus pesticides, Reproducibility, SERS, Selectivity, Soil sample, Surface-assisted MOF growth,
• Publikační typ
• časopisecké články MeSH

Nowadays, functionalization of the plasmon-supported nanostructured surface is considered as a powerful tool for tumour cell recognition. In this study, the SERS on a surface plasmon polariton-supported gold grating functionalized with folic acid was used to demonstrate an unpretentious recognition of melanoma-associated fibroblasts. Using cultivation media conditioned by different cells, we were able to detect reproducible differences in the secretome of melanoma-associated and normal control fibroblasts. The homogeneous distribution of plasmon energy along the grating surface was proved to provide excellent SERS signal reproducibility, while, to increase the affinity of (bio)molecules to SERS substrate, folic acid molecules were covalently grafted to the gold gratings. As proof of concept, fibroblasts were cultured in vitro, and culture media from the normal and tumour-associated lines were collected and analysed with our proposed SERS substrates. Identifying individual peaks of the Raman spectra as well as comparing their relative intensities, we showed that the proposed functional SERS platform can recognise the melanoma-associated cells without the need for further statistical spectral evaluation directly. We also demonstrated that the SERS chip created provided a stable SERS signal over a period of 90 days without loss of sensitivity. Graphical abstract.

• Klíčová slova
• Cancer, Melanoma, Reproducibility of SERS, SERS sensor, Surface modification,
• MeSH
• fibroblasty asociované s nádorem chemie   patologie   MeSH
• kovové nanočástice chemie   MeSH
• kultivované buňky MeSH
• kyselina listová chemie   MeSH
• lidé MeSH
• melanom chemie   patologie   MeSH
• nádorové buňky kultivované MeSH
• povrchové vlastnosti MeSH
• Ramanova spektroskopie metody   MeSH
• zlato chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kyselina listová MeSH
• zlato MeSH

Surface-enhanced Raman scattering (SERS) spectroscopy is an extremely sensitive analytical technique that is capable of identifying the vibration signatures of target molecules up to single-molecule sensitivity. In this work, the ultrahigh sensitivity of SERS has been achieved through the immobilization of sharp-edges specific nanoparticles - so-called gold multibranched NPs (AuMs) on the silver grating surface through the biphenyl dithiol. This approach allows combining the extremely high SERS enhancement factor (better than that in the case of AuMs immobilized on the flat Ag film) with perfect reproducibility of Raman signals. The grating was created on the polymer substrate using the excimer laser modification and further metal deposition and has an "active" area 5 × 10 mm2, enabling the macroscale SERS substrate preparation. The wet-chemistry synthesized AuMs were then immobilized on the grating surface and the produced structure allows SERS measurements with a portable Raman spectrophotometer. The prepared structures were checked using the AFM, UV-Vis, and Raman spectroscopy techniques.

• Publikační typ
• časopisecké články MeSH

In this contribution, we propose a novel functional surface-enhanced Raman spectroscopy (SERS) platform for the detection of one of the most hazardous heavy metal ions, Hg2+. The design of the proposed sensor is based on the combination of surface plasmon-polariton (SPP) supporting gold grating with the high homogeneity of the response and enhancement and mercaptosuccinic acid (MSA) based specific recognition layer. For the first time, diazonium grafted 4-ethynylphenyl groups have undergone the sunlight-induced thiol-yne reaction with MSA in the presence of Eosine Y. The developed SERS platform provides an extremely sensitive, selective, and convenient analytical procedure to detect mercury ions with limit of detection (LOD) as low as 10-10 M (0.027 µg/L) with excellent selectivity over other metals. The developed SERS sensor is compatible with a portable SERS spectrophotometer and does not require the expensive equipment for statistical methods of analysis.

• Klíčová slova
• Hg2+ sensors, SERS, surface modification, water analysis,
• Publikační typ
• časopisecké články MeSH

A dual-mode functional chip for chiral sensing based on mobile phone wettability measurements and portable surface-enhanced Raman spectroscopy (SERS) is reported. The plasmon-active regular gold grating surface was covalently grafted with chiral recognition moieties, l- or d-enantiomers of tartaric acid, making stereoselective discrimination of chiral amines possible. Chiral sensing of amines includes two modes of analysis, performed subsequently on the one chip surface with portable instruments (mobile phone equipped with a camera and developed application (app) Dropangle and a portable Raman spectrometer). First, the wettability changes, caused by enantioselective entrapping of chiral amines, are monitored and analyzed via our mobile phone app, allowing detection of the optical configuration and concentration of enantiomers with 1 order of magnitude accuracy. Second, SERS measurement on the same chip provides information about the chemical structure of entrapped amines and allows calculation of the enantiomeric excess with great accuracy. The applicability of the developed chip is demonstrated on a variety of chiral amines, including tyrosine, cysteine, dopamine (DOPA), and dextromethorphan in analytical solutions and in commercially available DOPA-containing drug. Moreover, we demonstrate that the chips could be regenerated and used repeatedly for at least five cycles.

• Klíčová slova
• SERS, chiral amines, chiral detection, double-mode analysis, wettability,
• MeSH
• aminy analýza   chemie   MeSH
• chytrý telefon MeSH
• mobilní aplikace MeSH
• Ramanova spektroskopie přístrojové vybavení   metody   MeSH
• smáčivost MeSH
• stereoizomerie MeSH
• tartaráty chemie   MeSH
• zlato chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aminy MeSH
• tartaráty MeSH
• tartaric acid MeSH Prohlížeč
• zlato MeSH

A spin-coating method was applied for the first time to prepare a colloid monolayer on the optical crossed gratings used as a template. Four polystyrene colloids of various nominal sizes and different surface charges were spin-coated on templates with periods matched to the particles size. Three types of coverage were described depending on the spin-coating parameters and particles type. The optimal coverage was obtained for all four particles sizes. A way of finding the right spin-coating parameters was proposed. The analysis of a coverage capability of polystyrene particles showed that neutral particles have the highest ability to order on the templates used. Large monolayered areas of ordered particles were used as a lithographic mask for generating a pattern of gold nanoparticles with a square symmetry. A few hundred square micrometers large, continuous and fully defect-free areas of gold nanoparticles were produced on the nearly entire surface of the templated substrates.

• MeSH
• analýza selhání vybavení MeSH
• design vybavení MeSH
• krystalizace metody   MeSH
• nanostruktury chemie   ultrastruktura   MeSH
• nanotechnologie přístrojové vybavení   MeSH
• polystyreny chemie   MeSH
• povrchová plasmonová rezonance přístrojové vybavení   MeSH
• rotace MeSH
• testování materiálů MeSH
• velikost částic MeSH
• zlato chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• polystyreny MeSH
• zlato MeSH

Plasmon catalysis has recently generated tremendous interest in the field of modern chemistry. Application of plasmon introduces the principally new stimulus for the activation of organic reactions, keeping the optical energy concentrated in the vicinity of plasmonic structure, creating an optical near-field enhancement as well as hot electron injection. In this work, for the first time, we presented a new way for the initiation of the azide-alkyne cycloaddition (AAC) using the surface plasmon-polariton wave, supported by the gold grating. With this concept in hand, the plasmon-active gold grating was functionalized with 4-ethynylbenzenediazonium compound. Then, surface-grafted 4-ethynylphenyl groups were plasmon activated and clicked with 4-azidobenzoic acid. Additional experiments allowed to exclude the potential effect of photon, heating, and metal impurities confirmed the key role of surface plasmon-polariton AAC activation. For the investigation of plasmon-induced AAC mechanism, 4-azidophenyl groups (instead of 4-ethynylphenyl groups) were also grafted to the grating surface. Further careful evaluation of reaction kinetics demonstrates that the AAC reaction rate is significantly higher in the case of acetylene activation than in the case of azide activation.

• Publikační typ
• časopisecké články MeSH

We report a new approach to characterization of thin (bio)molecular films based on spectroscopy of Bragg-scattered surface plasmons (BSSPs) generated by diffraction-coupling of counterpropagating surface plasmons on a metal-coated diffraction grating. The BSSPs exhibit fields with different penetration depths into the medium adjacent to the metal and therefore exhibit unequal sensitivities to the presence of (bio)molecular films on the surface of the metal. Therefore, spectroscopy of BSSPs enables in situ observation of the formation of biomolecular films and determination of both their refractive index and thickness. We demonstrate this capacity of spectroscopy of BSSPs in a model experiment in which growth of protein layers on a gold surface is studied.

• MeSH
• biopolymery chemie   MeSH
• membrány umělé * MeSH
• povrchová plasmonová rezonance metody   MeSH
• radiační rozptyl MeSH
• refraktometrie metody   MeSH
• spektrální analýza metody   MeSH
• světlo MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• biopolymery MeSH
• membrány umělé * MeSH

This paper introduces a novel class of low-loss and cost-effective optical planar structures tailored for magnetic detection applications. These structures represent unconventional magneto-plasmonic devices specifically optimized for an 'optical switch' configuration. The structure consists of a 1D deep sinusoidal gold grating covered by a thin cobalt layer. In this unique arrangement, the excited plasmon induces a high-contrast switching phenomenon between the reflected free space intensity of specular (0th) and -1st diffracted orders, sensitive to any transverse magnetic fields applied to the cobalt layer. The use of these two distinct diffracted orders induces differential measurements, effectively mitigating common drift and perturbations. This innovative approach results in an enhanced detection sensitivity, showcasing the potential of these structures for advanced magnetic field sensing applications.

• Klíčová slova
• magnetic field sensors, magneto-optics, plasmonic,
• Publikační typ
• časopisecké články MeSH