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Colloidal copper phosphide (Cu3−xP) nanocrystals are attractive electronic materials due to their ability to support excess delocalized holes, with both synthesis and dynamic redox modulation allowing tuning of localized surface plasmon resonance (LSPR) absorption in the near-IR. This dissertation presents developments in the colloidal syntheses and post-synthetic redox chemistries of high-quality Cu3−xP nanoplatelets with the attainment of tunable nanocrystallite lateral sizes, LSPR energies, compositions, and optoelectronic properties. A one-pot, colloidal synthesis of Cu3−xP nanoplatelets with copper halide salt and aminophosphine in the presence of oleylamine is presented in Chapter 2. The reactivity of an in situ copper-phosphorus precursor is modulated by varying precursor composition and coordinating solvent ratio to tune nanocrystal lateral size. Oleylamine-to-aminophosphine molar ratio is found to alter particle nucleation activity and access atom-efficient size tuning. By modulating precursor reactivity, the syntheses presented in Chapter 2 are used to access nanocrystals with lateral sizes of 6.1–23 nm and LSPR energies of 709–861 meV. The low polydispersity, size- and LSPR-tunability and colloidal stability make aminophosphine-synthesized Cu3−xP nanocrystals promising candidates for investigations into factors governing their LSPR energy, around which the findings of the subsequent chapter are based. Three copper-coupled redox chemistries are presented in Chapter 3 which allow post-synthetic modulation of the delocalized hole concentrations and corresponding LSPR absorption in colloidal Cu3−xP nanocrystals. Changes in the structural, optical, and compositional properties are evaluated by powder X-ray diffraction, electronic absorption spectroscopy, 31P magic-angle spinning solid-state nuclear magnetic resonance spectroscopy and elemental analysis. The redox chemistries are shown to access nanocrystals with LSPR energies of 660–890 meV, a larger range tha

In recent years, nanoparticles have emerged as an important player in a broad range of applications, especially thanks to recent advances in their synthesis. The silver and copper nanoparticles are often used due to their antibacterial and fungicidal activities, and this article presents the results of the nanoparticle synthesis using electrical glow discharge generated directly in a volume of their salt solutions. Therefore, there is no influence of air (i.e. reactive nitrogen species) as it is usual in other commonly used approaches. Nanoparticles were prepared under various experimental conditions, and they were characterized by ultraviolet/visible spectrometry, dynamic light scattering, X-ray photoelectron spectroscopy, and high-resolution scanning electron microscopy. Particles were produced without any surfactant or stabilizing agent, and some of them showed higher resistance against agglomeration during their short-term (days) storage. The nanoparticle formation mechanism was confirmed by the fast camera imaging. Thus, the developed approach can be applied for simple environmentally friendly nanoparticle production for various applications., IV posledních letech je pozorován prudký nárůst aplikací nanočástic, a to zejména díky progresu v jejich přípravě. Stříbrné a měděné nanočástice jsou často užívány pro svou antimikrobiální a antimykotickou aktivitu. Článek prezentuje syntézu těchto annočástic pomocí plazmatu generovaného přímo ve vodném roztoku anorganických solí, tedy bez přístupu vzduchu. Proces přípravy probíhal za různých podmínek. K charakterizaci nanočástic bylo využito UVS-VIS spektrometrie, dynamického rozptylu světla, rentgenovské fotoelektronové spektormetrie avysoce rozlišující skenovací elektronové mikroskopie. Částice byly připravovány bez použití surfaktantů nebo jiných stabilizačních činidel, a některé z nich nevykazovaly po řadu dní aglomerační tendence. Mechanismus vzniku nanočástic byl potvrzen s využitím snímání vysokorychlostní kamerou. Použitý přístup představuje efektivní a přírodě přátelský postup přípravy kovových nanočástic.

©2011 Elsevier Ltd. This work has been partially supported by Spanish Ministry of Science research projects SPRINT (CTQ2009-10550) and MAX-MART (CTQ2009-14565-C03-01), and the Community of Madrid research grants FACTOTEM II (S2009/ESP-1781) and FUTURSEN (CM-S-505/AMB/0374) as well as the European Social Fund and the European Fund for Regional Development., We present the results of a chemical attack on the optical fiber surface previous to the deposition of the double layer (metal plus dielectric) in Double-layer uniform-waist tapered fibers (DLUWTs) used for the development of SPR sensors. It is shown how this simple chemical treatment increases the roughness of the surface and permits improvement of the stability of the deposits and the general performance of the sensors. The obtained devices are robust and very compact, their sensitivity is good and repeatability of the measurements is remarkably increased. The procedure can be useful for any fiber-optic sensor., Comunidad de Madrid, Ministerio de Ciencia e Innovación (MICINN), European Social Fund, European Fund for Regional Development, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2009 Elsevier B.V. This work has been partially supported by Spanish Government research project NESTOR, ref. CTM2004-03899; Comunidad de Madrid research project FUTURSEN, ref. S-0505/AMB-0374 and by Proyecto de Investigación Santander/Complutense, ref. PR34/07-15886. This work was supported partially by the Portuguese Government – Fundação para a Ciência e Tecnologia (FCT) through the grant SFRH/BD/30086/2006. N. Díaz-Herrera is thankful for the grant within the program ‘Becas Internacionales Universidad Complutense/Empresa Flores Valles 2008’., In this work a new configuration of a refractometric sensor for aqueous solutions based on the combination of surface plasmon resonance (SPR) with fibre Bragg gratings (FBG) is presented. Two FBGs are selected having reflection maxima in each side of the plasmon resonance peak. These FBGs enable a different processing scheme for the information provided by the SPR transducer. This improved interrogation method increases the sensitivity and resolution of the sensor compared with those obtained with the usual method of tracking the spectral transmittance minimum and makes the system performance independent of optical source power fluctuations. The experimental results obtained with a double-layer uniform-waist tapered fibre show the feasibility of this approach and its applicability in SPR-based biosensors that must face very exigent measuring conditions., Spanish Government, Comunidad de Madrid, Proyecto de Investigación Santander/Complutense, Portuguese Government – Fundação para a Ciência e Tecnologia (FCT), Universidad Complutense de Madrid, Flores Valles, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2013 Elsevier B.V. This work has been partially supported by Spanish Ministry of Science research projects SPRINT (reference CTQ2009-10550), by the Community of Madrid project FACTOTEM II (reference S2009/ESP-1781) and by the European Social Fund and the European Fund for Regional Development., Doubly deposited uniform-waist tapered optical fibers (DLUWTs) have shown their versatility and good performance as basis for surface plasmon resonance (SPR) sensors for a variety of wavelength ranges. In this work we experimentally show how these devices can be employed to extend the technology of SPR fiber sensors to the visible region, down to about 530 nm, with remarkable results in terms of sensitivity, plasmon definition and the availability of multiple plasmon resonances for each configuration. In this way, DLUWTs can be used to cover a range of more than 1000 nm for aqueous media only by changing the thickness of the deposits. Also, it is shown how these results can be used with the so-called absorption method to make selective the response of the sensors and a study is made on the influence of the taper waist in the performance of the devices. The number of SPR fiber sensors working in the visible region, of great interest in biological research, that have been depicted in the literature is very small, and the sensors that we present here notably improve their performance., Comunidad de Madrid, Ministerio de Ciencia e Innovación (MICINN), European Social Fund, European Fund for Regional Development, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

The continuous flow reverse water gas shift (rWGS) process was efficiently catalyzed by a plasmonic Au/TiO2 nanocatalyst using sunlight as sole and sustainable energy source. The influence of the catalyst bed thickness on the CO production rate was studied, and three different catalytic regimes were identified as direct plasmon catalysis (DPC), shielded plasmon catalysis (SPC) and unused plasmon catalysis (UPC). The CO2 : H2 ratio was optimized to 4 : 1 and a maximum CO production rate of 7420 mmol ⋅ m−2 ⋅ h−1 was achieved under mild reaction conditions (p=3.5 bar, no external heating, Ee=14.0 kW ⋅ m−2), corresponding to an aparent quantum efficiency of 4.15%. The stability of the Au/TiO2 catalyst was studied for 110 h continuous operation, maintaining more than 82% of the initial CO production rate. On/off experiments mimicking discontinuous sunlight powered processing furthermore showed that the Au/TiO2 catalyst was stable for 8 consecutive runs.

Surface plasmon resonance (SPR) is the collective oscillation of frequency-matched free-space photons and surface electrons at a metal/dielectric interface. Their inherent sensitivity to refractive index changes and ability to couple with exciton species and enhance light-matter interaction make them ideal candidates for low-concentration analyte detection compared to conventional biosensors. The use of metal nanostructures and nanomaterials to excite SPR represents the current state-of-the-art. However, the challenges associated with repeatable synthesis of uniform nanomaterials, complex nanostructure fabrication, low SPR generation efficiency and limited understanding of the mechanism of plasmon-exciton coupling for signal amplification have motivated the search for alternative architectures and procedures. The uniform and repeatable gold nanoslit (NS) and nanoledge (NL) array architectures offers a promising route towards addressing the above issues, and hence this research attempts to take advantage of these platforms to achieve efficient SPR generation and exciton coupling for biosensing applications. The overarching scope of this dissertation extends to the design, fabrication, and optimization of metal NS and NL structures for SPR generation and sensing applications. Emphasis is placed on investigating the mechanism of optical signal enhancement arising from plasmon-exciton coupling (PEC) with particular focus on (a) exploring the role of geometry and size of the nanostructures (b) examining the influence of SPR spectral mode overlap with exciton’s absorption and/or emission energies on the overall optical signal in a NS or NL system, and (c) investigating the analytical sensitivity and signal transduction of the PEC system to biomolecular interactions. The nanoimprinting technique based on soft lithography for NS fabrication, which is used in this work for NS array fabrication, required addressing a critical issue, namely PDMS diffusion into nanoscale patter

The correct detection and quantification of pollutants in water is key to regulating their presence in the environment. Biosensors offer several advantages, such as minimal sample preparation, short measurement times, high specificity and sensibility and low detection limits. The purpose of this review is to explore the different types of optical biosensors, focusing on their biological elements and their principle of operation, as well as recent applications in the detection of pollutants in water. According to our literature review, 33% of the publications used fluorescence-based biosensors, followed by surface plasmon resonance (SPR) with 28%. So far, SPR biosensors have achieved the best results in terms of detection limits. Although less common (22%), interferometers and resonators (4%) are also highly promising due to the low detection limits that can be reached using these techniques. In terms of biological recognition elements, 43% of the published works focused on antibodies due to their high affinity and stability, although they could be replaced with molecularly imprinted polymers. This review offers a unique compilation of the most recent work in the specific area of optical biosensing for water monitoring, focusing on both the biological element and the transducer used, as well as the type of target contaminant. Recent technological advances are discussed.

Recent advancements in life science research have greatly improved our understanding of various intricate biological systems, some of which are affiliated with complex diseases. While a great deal of progress has been made towards the comprehension of relevant biophysical interactions, many remain poorly understood. This is especially true for protein interactions involving the cellular membrane. Of the analytical strategies developed for investigating molecular interactions, surface plasmon resonance (SPR) provides marked technical advantages and has become a cornerstone for these studies. However, the SPR method is still facing challenges, from both technical aspects and investigation of diseases, which are the focus of this Dissertation. SPR is susceptible to misidentification in biological matrices, due to cross-reactive and nonspecific interactions. The lack of reliable curved biomimetic membrane platforms has limited the investigation on various disease related protein interactions. The presented Dissertation aims to provide solutions to these challenges through developing novel biomimetic membrane platforms, robust post data acquisitions analysis strategies, and antifouling protocols. Chapter 2 showcases the development of a self-assembled pseudo-myelin sheath microarray. The platform and developed antifouling protocol were shown to be capable of detecting three multiple sclerosis (MS) specific anti-ganglioside antibodies in 10 % serum. Chapter 3 expands and improves upon the platform presented in Chapter 2. The MS specific antibodies were detected at disease relevant concentrations, 3 ng/mL to 25 ng/mL, in undiluted human serum. Machine learning algorithms were applied to facilitate the differentiation and identification of the highly cross reactive analyte-antigen interactions in a clinical setting. In Chapter 4, the characterization and development of a tunable curved membrane mimicking platform is presented. Through the use of statistical analysis, simula

[Abstract] Plasmonic nanoparticles (NPs) exhibit extraordinary optical properties that stem from their ability to sustain localized surface plasmon resonances. These resonances can be finely tuned by carefully controlling the morphology of the particles, allowing for optimization across a diverse range of applications. Recently, preparing chiral morphologies for these NPs has received considerable attention because it may provide important advantages in fields such as biomedicine. Thus, this undergraduate project focuses on the preparation of a novel type of plasmonic chiral NPs, i.e., chiral gold nanostars. This TFG has been divided into three parts. The first part focuses on synthesizing and characterizing achiral gold nanostars, utilizing UV-Vis spectroscopy and TEM to analyze their morphological and optical properties. The second part involved attempting to introduce chirality into the gold nanostars by replacing the previous surfactant with a chiral one. Unfortunately, the desired results were not achieved. Consequently, in the third part, a new chiral surfactant was synthesized, although due to the project's limited duration, the verification of its effect on achieving chirality in the gold nanostars could not be completed. The chiral surfactant was characterized using 1H-NMR, 13C-NMR spectroscopy, and MS spectrometry., {Resumo] As nanopartículas plasmónicas (NPs) presentan propiedades ópticas extraordinarias que se derivan da súa capacidade para manter as resonancias plasmónicas de superficie localizadas. Estas resonancias pódense afinar controlando coidadosamente a morfoloxía das partículas, permitindo a optimización nunha ampla gama de aplicacións. Recentemente, a preparación de morfoloxías quirais para estes NP recibiu unha atención considerable porque pode proporcionar importantes vantaxes en campos como a biomedicina. Polo tanto, este proxecto de pregrado céntrase na preparación dun novo tipo de NPs quirais plasmónicas, as nanoestrelas quirais de ouro. Este TFG dividiuse en tres partes. A primeira parte céntrase na síntese e caracterización de nanoestrelas aquirales de ouro, utilizando espectroscopia UV-Vis e TEM para analizar as súas propiedades morfolóxicas e ópticas. A segunda parte consistiu en intentar introducir quiralidade nas nanoestrelas de ouro substituíndo o tensioactivo anterior por outro quiral. Desafortunadamente, non se conseguiron os resultados desexados. En consecuencia, na terceira parte, sintetizouse un novo surfactante quiral, aínda que debido á limitada duración do proxecto non se puido completar a verificación do seu efecto na consecución da quiralidade nas nanoestrelas de ouro. O surfactante quiral caracterizouse por espectroscopia 1H-RMN, 13C-RMN e espectrometría MS., [Resumen] Las nanopartículas plasmónicas (NPs) exhiben propiedades ópticas extraordinarias que se derivan de su capacidad para sostener resonancias de plasmones superficiales localizadas. Estas resonancias se pueden ajustar con precisión controlando cuidadosamente la morfología de las partículas, lo que permite la optimización en una amplia gama de aplicaciones. Recientemente, la preparación de morfologías quirales para estas NPs ha recibido una atención considerable porque puede proporcionar importantes ventajas en campos como la biomedicina. Por lo tanto, este proyecto de pregrado se centra en la preparación de un nuevo tipo de NP quirales plasmónicas, las nanoestrellas de oro quirales. Este TFG se ha dividido en tres partes. La primera parte se centra en sintetizar y caracterizar nanoestrellas de oro aquirales, utilizando espectroscopia UV-Vis y TEM para analizar sus propiedades morfológicas y ópticas. La segunda parte consistió en intentar introducir quiralidad en las nanoestrellas de oro reemplazando el surfactante anterior por uno quiral. Desafortunadamente, no se lograron los resultados deseados. En consecuencia, en la tercera parte, se sintetizó un nuevo surfactante quiral, aunque debido a la duración limitada del proyecto, no se pudo completar la verificación de su efecto para lograr la quiralidad en las nanoestrellas de oro. El tensioactivo quiral se caracterizó mediante espectroscopia 1H-NMR, 13C-NMR y espectrometría MS.

In recent years, nanoparticles have emerged as an important player in a broad range of applications, especially thanks to recent advances in their synthesis. The silver and copper nanoparticles are often used due to their antibacterial and fungicidal activities, and this article presents the results of the nanoparticle synthesis using electrical glow discharge generated directly in a volume of their salt solutions. Therefore, there is no influence of air (i.e. reactive nitrogen species) as it is usual in other commonly used approaches. Nanoparticles were prepared under various experimental conditions, and they were characterized by ultraviolet/visible spectrometry, dynamic light scattering, X-ray photoelectron spectroscopy, and high-resolution scanning electron microscopy. Particles were produced without any surfactant or stabilizing agent, and some of them showed higher resistance against agglomeration during their short-term (days) storage. The nanoparticle formation mechanism was confirmed by the fast camera imaging. Thus, the developed approach can be applied for simple environmentally friendly nanoparticle production for various applications.

In recent years, nanoparticles have emerged as an important player in a broad range of applications, especially thanks to recent advances in their synthesis. The silver and copper nanoparticles are often used due to their antibacterial and fungicidal activities, and this article presents the results of the nanoparticle synthesis using electrical glow discharge generated directly in a volume of their salt solutions. Therefore, there is no influence of air (i.e. reactive nitrogen species) as it is usual in other commonly used approaches. Nanoparticles were prepared under various experimental conditions, and they were characterized by ultraviolet/visible spectrometry, dynamic light scattering, X-ray photoelectron spectroscopy, and high-resolution scanning electron microscopy. Particles were produced without any surfactant or stabilizing agent, and some of them showed higher resistance against agglomeration during their short-term (days) storage. The nanoparticle formation mechanism was confirmed by the fast camera imaging. Thus, the developed approach can be applied for simple environmentally friendly nanoparticle production for various applications.

In recent years, nanoparticles have emerged as an important player in a broad range of applications, especially thanks to recent advances in their synthesis. The silver and copper nanoparticles are often used due to their antibacterial and fungicidal activities, and this article presents the results of the nanoparticle synthesis using electrical glow discharge generated directly in a volume of their salt solutions. Therefore, there is no influence of air (i.e. reactive nitrogen species) as it is usual in other commonly used approaches. Nanoparticles were prepared under various experimental conditions, and they were characterized by ultraviolet/visible spectrometry, dynamic light scattering, X-ray photoelectron spectroscopy, and high-resolution scanning electron microscopy. Particles were produced without any surfactant or stabilizing agent, and some of them showed higher resistance against agglomeration during their short-term (days) storage. The nanoparticle formation mechanism was confirmed by the fast camera imaging. Thus, the developed approach can be applied for simple environmentally friendly nanoparticle production for various applications.

The Envelope (E) protein of SARS-CoV-2 plays a key role in virus maturation, assembly, and virulence mechanisms. The E protein is characterized by the presence of a PDZ-binding motif (PBM) at its C-terminus that allows it to interact with several PDZ-containing proteins in the intracellular environment. One of the main binding partners of the SARS-CoV-2 E protein is the PDZ2 domain of ZO1, a protein with a crucial role in the formation of epithelial and endothelial tight junctions (TJs). In this work, through a combination of analytical ultracentrifugation analysis and equilibrium and kinetic folding experiments, we show that ZO1-PDZ2 domain is able to fold in a monomeric state, an alternative form to the dimeric conformation that is reported to be functional in the cell for TJs assembly. Importantly, surface plasmon resonance (SPR) data indicate that the PDZ2 monomer is fully functional and capable of binding the C-terminal portion of the E protein of SARS-CoV-2, with a measured affinity in the micromolar range. Moreover, we present a detailed computational analysis of the complex between the C-terminal portion of E protein with ZO1-PDZ2, both in its monomeric conformation (computed as a high confidence AlphaFold2 model) and dimeric conformation (obtained from the Protein Data Bank), by using both polarizable and nonpolarizable simulations. Together, our results indicate both the monomeric and dimeric states of PDZ2 to be functional partners of the E protein, with similar binding mechanisms, and provide mechanistic and structural information about a fundamental interaction required for the replication of SARS-CoV-2.

Detecting, identifying, and characterizing molecules and structures as the substance of life are essential steps toward unveiling their role as a sole entity or more commonly as a part of a larger molecular assembly for specific biological functionalities. Next, it is of pivotal importance to translate the acquired knowledge of molecular structures and their activity to a more comprehensive understanding of the biological process, such as the biochemical foundations of diseases or metabolic disorders. The aim and ultimate outcomes of this thesis were to address these two aspects by offering new analytical strategies such as focusing on the molecular structure assessment of small molecules, including drug metabolites and potential biomarkers, and drug targets. Addressing challenges encountered in protein characterization and protein interactions studies. And lastly, taking a step forward and analyzing a dynamic chemical reaction in an online fashion by mass, tandem mass, and ion mobility spectrometry.

Monoclonal antibody (mAb) therapy is one of the most promising immunotherapies that have shown the potential to prevent or neutralize the effects of COVID-19 in patients at very early stages, with a few formulations recently approved by the European and American medicine agencies. However, a main bottleneck for their general implementation resides in the time-consuming, laborious, and highly-specialized techniques employed for the manufacturing and assessing of these therapies, excessively increasing their prices and delaying their administration to the patients. We propose a biomimetic nanoplasmonic biosensor as a novel analytical technique for the screening and evaluation of COVID-19 mAb therapies in a simpler, faster, and reliable manner. By creating an artificial cell membrane on the plasmonic sensor surface, our label-free sensing approach enables real-time monitoring of virus-cell interactions as well as direct analysis of antibody blocking effects in only 15 min assay time. We have achieved detection limits in the 102 TCID50/mL range for the study of SARS-CoV-2 viruses, which allows to perform neutralization assays by only employing a low-volume sample with common viral loads. We have demonstrated the accuracy of the biosensor for the evaluation of two different neutralizing antibodies targeting both Delta and Omicron variants of SARS-CoV-2, with half maximal inhibitory concentrations (IC50) determined in the ng/mL range. Our user-friendly and reliable technology could be employed in biomedical and pharmaceutical laboratories to accelerate, cheapen, and simplify the development of effective immunotherapies for COVID-19 and other serious infectious diseases or cancer.

Antimicrobial resistance threatens the eradication of infectious diseases and impairs the efficacy of available therapeutics. The bacterial SOS pathway is a conserved response triggered by genotoxic stresses and represents one of the principal mechanisms that lead to resistance. The RecA recombinase acts as a DNA-damage sensor inducing the autoproteolysis of the transcriptional repressor LexA, thereby derepressing SOS genes that mediate DNA repair, survival to chemotherapy, and hypermutation. The inhibition of such pathway represents a promising strategy for delaying the evolution of antimicrobial resistance. We report the identification, via llama immunization and phage display, of nanobodies that bind LexA with sub-micromolar affinity and block autoproteolysis, repressing SOS response in Escherichia coli. Biophysical characterization of nanobody-LexA complexes revealed that they act by trapping LexA in an inactive conformation and interfering with RecA engagement. Our studies pave the way to the development of new-generation antibiotic adjuvants for the treatment of bacterial infections., info:eu-repo/semantics/published

Hot-hole injection from plasmonic metal nanoparticles to the valence band of p-type semiconductors and reduction by hot electrons should be improved for efficient and tuneable reduction to obtain beneficial chemical compounds. We employed the concept of modal strong coupling between plasmons and a Fabry-Perot (FP) nanocavity to enhance the hot-hole injection efficiency. We fabricated a photocathode composed of gold nanoparticles (Au-NPs), p-type nickel oxide (NiO), and a platinum film (Pt film) (ANP). The ANP structure absorbs visible light over a broad wavelength range from 500 nm to 850 nm via hybrid modes based on the modal strong coupling between the plasmons of Au-NPs and the FP nanocavity of NiO on a Pt film. All wavelength regions of the hybrid modes of the modal strong coupling system promoted hot-hole injection from the Au-NPs to NiO and proton/water reduction by hot electrons. The incident photon-to-current efficiency based on H-2 evolution through water/proton reduction by hot electrons reached 0.2 % at 650 nm and 0.04 % at 800 nm.

Modulating near-field radiative heat transfer (NFRHT) with a high dynamic range is challenging in nanoscale thermal science and engineering. Modulation depths [(maximum value - minimum value)/(maximum value + minimum value) × 100%] of ≈2% to ≈15.7% have been reported with matched modes, but breaking the constraint of mode matching theoretically allows for higher modulation depth. We demonstrate a modulation depth of ≈32.2% by a pair of graphene-covered SU8 heterostructures at a gap distance of ≈80 nm. Dissimilar Fermi levels tuned by bias voltages enable mismatched surface plasmon polaritons which improves the modulation. The modulation depth when switching from a matched mode to a mismatched mode is ≈4.4-fold compared to that when switching between matched modes. This work shows the importance of symmetry in polariton-mediated NFRHT and represents the largest modulation depth to date in a two-body system with fixed gap distance and temperature., QC 20230602

Increasing metal ion contamination in the environment can cause severe effects towards human health. Hence, it is important to detect metal ion at low concentration for continuous monitoring of the surrounding environment. In this study, nanocrystalline cellulose/graphene oxide (NCC/GO) based thin film has been developed for metal ion sensing using surface plasmon resonance (SPR) technique. The properties of the NCC/GO thin film was confirmed by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) by showing all the functional groups of the composite. Moreover, the atomic force microscopy (AFM) result shows that the thin film roughness increased after the combination of NCC and GO. Conversely, the optical properties of the NCC/GO thin film were characterized by Ultraviolet-Visible spectroscopy (UV-Vis) where the absorbance peak can be observed in the range of 280 to 300 nm. Based on the band gap energy analysis, the NCC/GO thin film has optical band gap of 4.00 eV. Meanwhile, the sensing properties of the NCC/GO thin film shows a good result where metal ions such as copper, zinc, and nickel ion can be detected as low as 0.01 ppm using SPR. Fitting of the SPR curves also reveals the real part refractive index, n and the imaginary part refractive index, k values found for the NCC/GO layer were 1.4240 and 0.2520, respectively with thickness of 9.5 nm. Interestingly when the NCC/GO thin film was exposed to metal ion, a clear change of refractive index and the thickness was observed. The sensitivity of the NCC/GO thin film for copper, zinc, and nickel ion detection was 3.271 ppm−1 , 2.579 ppm−1 , and 1.509 ppm−1 respectively. In addition, the NCC/GO thin film also has high affinity towards copper ion with binding affinity constant of 4.075  103 M-1 compared to zinc and nickel ion at 2.579 ppm−1 and 1.509 ppm−1 respectively. Furthermore, the NCC/GO thin film incorporated with copper ionophore has successfully increased the sensitivity and sel

Increasing metal ion contamination in the environment can cause severe effects towards human health. Hence, it is important to detect metal ion at low concentration for continuous monitoring of the surrounding environment. In this study, nanocrystalline cellulose/graphene oxide (NCC/GO) based thin film has been developed for metal ion sensing using surface plasmon resonance (SPR) technique. The properties of the NCC/GO thin film was confirmed by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) by showing all the functional groups of the composite. Moreover, the atomic force microscopy (AFM) result shows that the thin film roughness increased after the combination of NCC and GO. Conversely, the optical properties of the NCC/GO thin film were characterized by Ultraviolet-Visible spectroscopy (UV-Vis) where the absorbance peak can be observed in the range of 280 to 300 nm. Based on the band gap energy analysis, the NCC/GO thin film has optical band gap of 4.00 eV. Meanwhile, the sensing properties of the NCC/GO thin film shows a good result where metal ions such as copper, zinc, and nickel ion can be detected as low as 0.01 ppm using SPR. Fitting of the SPR curves also reveals the real part refractive index, n and the imaginary part refractive index, k values found for the NCC/GO layer were 1.4240 and 0.2520, respectively with thickness of 9.5 nm. Interestingly when the NCC/GO thin film was exposed to metal ion, a clear change of refractive index and the thickness was observed. The sensitivity of the NCC/GO thin film for copper, zinc, and nickel ion detection was 3.271 ppm−1 , 2.579 ppm−1 , and 1.509 ppm−1 respectively. In addition, the NCC/GO thin film also has high affinity towards copper ion with binding affinity constant of 4.075  103 M-1 compared to zinc and nickel ion at 2.579 ppm−1 and 1.509 ppm−1 respectively. Furthermore, the NCC/GO thin film incorporated with copper ionophore has successfully increased the sensitivity and sel

We report on the synthesis of hyaluronan (HA) brush-like copolymers and their application as antagonists of tumorigenic CD44-HA interactions. HA (4.8 kDa, ca. 24 saccharides) was grafted on 2-hydrohyethyl methacrylate (HEMA) by end-on oxime ligation. The obtained copolymers were compared with low and high molecular weight HA in terms of hydrolysis kinetics in the presence of hyaluronidase (isothermal titration calorimetry) and interactions with CD44 (surface plasmon resonance). The results evidenced that the high molecular weight HA and HA-g-HEMA have a much higher affinity to CD44 than low molecular weight HA. Additionally, slower enzymatic degradation was observed for the copolymer, making it an excellent candidate for active targeting of tumorigenic CD44-HA interactions. We, therefore, investigated the effect of the copolymer on cancer cell lines with different expression of CD44 and observed an efficient declustering of CD44 that is usually associated with reduction of metastasis and drug resistance

Hot-hole injection from plasmonic metal nanoparticles to the valence band of p-type semiconductors and reduction by hot electrons should be improved for efficient and tuneable reduction to obtain beneficial chemical compounds. We employed the concept of modal strong coupling between plasmons and a Fabry-Perot (FP) nanocavity to enhance the hot-hole injection efficiency. We fabricated a photocathode composed of gold nanoparticles (Au-NPs), p-type nickel oxide (NiO), and a platinum film (Pt film) (ANP). The ANP structure absorbs visible light over a broad wavelength range from 500 nm to 850 nm via hybrid modes based on the modal strong coupling between the plasmons of Au-NPs and the FP nanocavity of NiO on a Pt film. All wavelength regions of the hybrid modes of the modal strong coupling system promoted hot-hole injection from the Au-NPs to NiO and proton/water reduction by hot electrons. The incident photon-to-current efficiency based on H-2 evolution through water/proton reduction by hot electrons reached 0.2 % at 650 nm and 0.04 % at 800 nm.

Biosensing is an ever-growing field of research, giving the floor to more and more innovations over the years to address the increasing needs of our society. Nowadays, research trends are essentially on the demand from medical, environmental, and agri-food industries. Biosensing is also undoubtedly highly multidisciplinary, blending closely Physics, Chemistry, Biology, Engineering and Biochemistry, as well as Electronic and Computer Sciences. Opportunities in terms of target analytes (proteins, hormones, enzymes, saccharides, etc.), designs and strategies are endless and new prototypes are constantly emerging. Focus is on developing more accurate, sensitive, and affordable biosensing tools for rapid and reliable Point-of-Care (POC) home-diagnoses. Integrations in current technologies such as smartphones or connected watches also play an important role. Sensors based on the surface plasmon resonance (SPR) phenomenon are well-adapted to meet the demand. Since their advent in the early nineties with first commercial devices, SPR-based biosensing technologies never ceased to progress. This involves recent classes of biosensors built on optical fibers such as plasmonic tilted fiber Bragg grating (TFBG) biosensors. This thesis has aimed to investigate new strategies in plasmonic TFBG technology to enhance performances and practicability in cancer biomarkers biosensing. A TFBG enables to build biocompatible and minimally invasive biosensors suitable for accurate and highly sensitive diagnoses. Its structure makes the optical fiber sensitive to its close surroundings while keeping all its advantages in terms of flexibility, resistance to harsh environment (temperature and pH), real-time monitoring and miniaturization. Once covered with a finely tailored gold layer, the SPR phenomenon can occur, and the sensitivity is drastically amplified. The SPR-TFBG is a versatile platform that can host miscellaneous biofunctionalization strategies (antibodies, aptamers, enzymes, etc.) t, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

Label-free biosensors, and especially those based on optical transducers like plasmonic or silicon photonic systems, have positioned themselves as potential alternatives for rapid and highly sensitive clinical diagnostics, on-site environmental monitoring, and for quality control in foods or other industrial applications, among others. However, most of the biosensor technology has not yet been transferred and implemented in commercial products. Among the several causes behind that, a major challenge is the lack of standardized protocols for sensor biofunctionalization. In this review, we summarize the most common methodologies for sensor surface chemical modification and bioreceptor immobilization, discussing their advantages and limitations in terms of analytical sensitivity and selectivity, reproducibility, and versatility. Special focus is placed on the suggestions of innovative strategies towards antifouling and biomimetic functional coatings to boost the applicability and reliability of optical biosensors in clinics and biomedicine. Finally, a brief overview of research directions in the area of device integration, automation, and multiplexing will give a glimpse of the future perspectives for label-free optical biosensors.

The dependence of plasmon resonance excitations in ultrafine (3-7 nm) gold nanoparticles on heating and melting is investigated. An integrated approach is adopted, where molecular dynamics simulations of the spatial and temporal development of the atoms constituting the nanoparticles generate trajectories out of which system conformations are sampled and extracted for calculations of plasmonic excitation cross sections which then are averaged over the sample configurations for the final result. The calculations of the plasmonic excitations, which take into account the temperature- and size-dependent relaxation of the plasmons, are carried out with a newly developed Extended Discrete Interaction Model (Ex-DIM) and complemented by multilayered Mie theory. The integrated approach clearly demonstrates the conditions for suppression of the plasmons starting at temperatures well below the melting point. We have found a strong inhomogeneous dependence of the atom mobility in the particle crystal lattice increasing from the center to its surface upon the temperature growth. The plasmon resonance suppression is associated with an increase of the mobility and in the amplitude of phonon vibrations of the lattice atoms accompanied by electron-phonon scattering. This leads to an increase in the relaxation constant impeding the plasmon excitation as the major source of the suppression, while the direct contribution from the increase in the lattice constant and its chaotization at melting is found to be minor. Experimental verification of the suppression of surface plasmon resonance is demonstrated for gold nanoparticles on a quartz substrate heated up to the melting temperature and above. This journal is © The Royal Society of Chemistry., QC 20220930

Understanding biomolecular interactions and cellular activities based on these interactions are important research topics in bioanalytical chemistry that can have a large impact on key fields such as drug discovery, biomedical sciences, and environmental monitoring. High performing biosensors are an essential part for this task. Effective sensing platforms with improved analytical performance and reduced cost are actively sought after and remain a major area of intense research endeavors. The goal of this thesis is to develop novel biosensing systems enabled by 3D printing technology and nanoscience for probing biochemical interactions and achieving cell lipidomic analysis.Surface plasmon resonance (SPR) biosensors have been wildly applied for biomolecular assays in a label-free fashion. The sensitivity of SPR sensors, however, still needs signal enhancement when dealing with trace amounts of analytes. Chapter 2 describes the fabrication and application of gold nanoparticles-coupled POPC liposomes nanoclusters for signal amplification for SPR sensors and the study of protein-membrane recognition on a biomimetic interface. By combining the large mass of liposomes and plasmonic coupling of the noble metal nanoparticles, the highly stable POPC-gold nanoparticles showed a large amplification effect and a 0.1 ng/mL LOD was achieved for cholera toxin detection. 3D printing technology has greatly impacted the bioanalytical fields by providing the fabrication capability with almost no geometric restriction, rapid prototyping, and low cost. Chapter 3 describes the design and fabrication of a Dove prism by 3D printing with transverse micropatterns for multiplexed sensing with SPR imaging. The sensitivity of the system was evaluated by bulk refractive index change and protein binding assays; both showed similar performance as compared to the SPR configuration using high end glass optics. 3D printing technology has been further applied to fabricating microfluidic chips for cell

Advances in life sciences in recent decades have revolutionized our understandingof biochemical and biophysical interactions associated with diseases and disorders of the human body. This newly acquired knowledge has fueled intense interest in a range of biotechnological strategies that can improve health outcomes, spanning from biosensors to drug development to tissue engineering. There is thus an increasing need for even better understanding of biomolecular interactions at nanoscale to explore new medical frontiers, and for powerful analytical tools of increasing complexity and diversity in multiplexed bioanalysis. Surface plasmon resonance (SPR) is a core optical spectroscopic principle in the bioanalytical sphere, and its label-free methodology for bioassays has been broadly applied in drug discovery, medical diagnosis, and environmental monitoring. Advances in materials sciences, however, have provided new opportunities for re-invention of the technique and expansion of the range of analyses by SPR. The aim of this dissertation is to develop and improve the fundamental technological diversity of SPR based techniques for enhanced biosensing applications.The main strategy for the development takes the form of integrating novelmethodologies and new materials to the SPR bioanalytical workflows. First, an orthogonal analytical platform was developed by combining SPR/SPR imaging with matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). A multistep functionalized plasmonic microarray was developed into a new mode (SPR-MALDI) for the sensitive detection of bacterial toxin proteins in complex environmental matrices. The combination of the techniques allowed for both quantitative determination and unambiguous qualitative identification of biological identity of the target. Second, SPR techniques were integrated with three-dimensional (3D) printing for enhancing analytical performance. A novel hybrid 3D printing and PDMS molding process was developed

An inexpensive virus detection scheme with high sensitivity and specificity is desirable for broad applications such as the COVID-19 virus. In this article, we introduce the localized surface plasmon resonance (LSPR) principle on the aggregation of antigen-coated gold nanoparticles (GNPs) to detect SARS-CoV-2 Nucleocapsid (N) proteins. Experiments show this technique can produce results observable by the naked eye in 5 min with a LOD (Limits of Detection) of 150 ng/ml for the N proteins. A comprehensive numerical model of the LSPR effect on the aggregation of GNPs has been developed to identify the key parameters in the reaction processes. The color-changing behaviors can be readily utilized to detect the existence of the virus while the quantitative concentration value is characterized with the assistance of an optical spectrometer. A parameter defined as the ratio of the light absorption intensity at the upper visible band region of 700 nm to the light absorption intensity at the peak optical absorption spectrum of the GNPs at 530 nm is found to have a linear relationship with respect to the N protein concentrations. As such, this scheme could be utilized as an inexpensive testing methodology for applications in POC (Point-of-Care) diagnostics to combat current and future virus-induced pandemics.

Current approaches based on electrophoretic, chromatographic or immunochemical principles have allowed characterizing multiple allergens, mapping their epitopes, studying their mechanisms of action, developing detection and diagnostic methods and therapeutic strategies for the food and pharmaceutical industry. However, some of the common structural features related to the allergenic potential of food proteins remain unknown, or the pathological mechanism of food allergy is not yet fully understood. In addition, it is also necessary to evaluate new allergens from novel protein sources that may pose a new risk for consumers. Technological development has allowed the expansion of advanced technologies for which their whole potential has not been entirely exploited and could provide novel contributions to still unexplored molecular traits underlying both the structure of food allergens and the mechanisms through which they sensitize or elicit adverse responses in human subjects, as well as improving analytical techniques for their detection. This review presents cutting-edge instrumental techniques recently applied when studying structural and functional aspects of proteins, mechanism of action and interaction between biomolecules. We also exemplify their role in the food allergy research and discuss their new possible applications in several areas of the food allergy field.

An improvement in random lasers based on a colloidal quantum dot (QD)/graphene-doped polymer was observed and attributed to multiple light-scattering and graphene surface plasmon resonance. The emission characteristics of quantum dots doped with graphene oxide and reduced graphene oxide were compared. The QD/reduced graphene oxide hybrid exhibited a lower laser emission threshold (~460 µJ/cm2). The emission modes and thresholds were strongly dependent on both the graphene doping concentration and the external temperature. Decreased plasmon coupling was the primary reason for lower QD/graphene laser emission with increasing temperature. The optimum reduced graphene oxide concentration was 0.2 wt.%. This work provides a practical approach to optimizing the threshold and stability of random laser devices, with potential applications in displays, sensors, and anti-counterfeiting labels. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

Hydroxyapatite (HAp) is the major component of all boney tissues in mammals. Because of this omnipresence in the living world, HAp possesses an exceptional biocompatibility. The downside of this omnipresence, however, comes in the form of its mild to moderate biological activities. One means of augmenting these activities involves the doping of HAp with foreign ions. Here, the first synthesis and characterization of HAp doped with germanium ions is being reported. Germanium was deliberately integrated into the crystal lattice of HAp in the form of germanate anions. Approximately two thirds of the germanate ions introduced into the hydrothermal solution got incorporated into the HAp lattice, yielding the approximate stoichiometry of Ca10-x(PO4)5.62+y(GeO3)0.38(OH)2-z. Germanates replaced the phosphates of stoichiometric HAp and induced the expansion of the HAp lattice both along the screw axis of the calcium ion hexagons and in the direction parallel to the basal plane. Simultaneously, the larger size and the triple valency of the germanate ion as compared to the smaller and trivalent phosphates prompted the bond distortion and charge compensation through defect formation, which reduced the crystallinity and increased the microstrain of the HAp lattice. Vibrational spectroscopic analyses corroborated these crystallographic effects by demonstrating the enhanced heterogeneity of the environments surrounding the active modes after germanate ions were incorporated into HAp. Conforming to La Châtelier's principle, this reduction of the crystallographic order increased the capacity of the material for integration of adventitious carbonates. However, the inclusion of germanate ions induced a partial shift of these carbonates to the hydroxyl channel sites, thus decreasing the ratio of the B-type carbonation to the A-type carbonation. Introduced into HAp, germanium acted as a superb regulator of the particle size and morphology, enhancing their fineness and uniformity. Inclus

Hot-hole injection from plasmonic metal nanoparticles to the valence band of p-type semiconductors and reduction by hot electrons should be improved for efficient and tuneable reduction to obtain beneficial chemical compounds. We employed the concept of modal strong coupling between plasmons and a Fabry-Perot (FP) nanocavity to enhance the hot-hole injection efficiency. We fabricated a photocathode composed of gold nanoparticles (Au-NPs), p-type nickel oxide (NiO), and a platinum film (Pt film) (ANP). The ANP structure absorbs visible light over a broad wavelength range from 500 nm to 850 nm via hybrid modes based on the modal strong coupling between the plasmons of Au-NPs and the FP nanocavity of NiO on a Pt film. All wavelength regions of the hybrid modes of the modal strong coupling system promoted hot-hole injection from the Au-NPs to NiO and proton/water reduction by hot electrons. The incident photon-to-current efficiency based on H-2 evolution through water/proton reduction by hot electrons reached 0.2 % at 650 nm and 0.04 % at 800 nm.

Advances in life sciences in recent decades have revolutionized our understandingof biochemical and biophysical interactions associated with diseases and disorders of the human body. This newly acquired knowledge has fueled intense interest in a range of biotechnological strategies that can improve health outcomes, spanning from biosensors to drug development to tissue engineering. There is thus an increasing need for even better understanding of biomolecular interactions at nanoscale to explore new medical frontiers, and for powerful analytical tools of increasing complexity and diversity in multiplexed bioanalysis. Surface plasmon resonance (SPR) is a core optical spectroscopic principle in the bioanalytical sphere, and its label-free methodology for bioassays has been broadly applied in drug discovery, medical diagnosis, and environmental monitoring. Advances in materials sciences, however, have provided new opportunities for re-invention of the technique and expansion of the range of analyses by SPR. The aim of this dissertation is to develop and improve the fundamental technological diversity of SPR based techniques for enhanced biosensing applications.The main strategy for the development takes the form of integrating novelmethodologies and new materials to the SPR bioanalytical workflows. First, an orthogonal analytical platform was developed by combining SPR/SPR imaging with matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). A multistep functionalized plasmonic microarray was developed into a new mode (SPR-MALDI) for the sensitive detection of bacterial toxin proteins in complex environmental matrices. The combination of the techniques allowed for both quantitative determination and unambiguous qualitative identification of biological identity of the target. Second, SPR techniques were integrated with three-dimensional (3D) printing for enhancing analytical performance. A novel hybrid 3D printing and PDMS molding process was developed

Hot-hole injection from plasmonic metal nanoparticles to the valence band of p-type semiconductors and reduction by hot electrons should be improved for efficient and tuneable reduction to obtain beneficial chemical compounds. We employed the concept of modal strong coupling between plasmons and a Fabry-Perot (FP) nanocavity to enhance the hot-hole injection efficiency. We fabricated a photocathode composed of gold nanoparticles (Au-NPs), p-type nickel oxide (NiO), and a platinum film (Pt film) (ANP). The ANP structure absorbs visible light over a broad wavelength range from 500 nm to 850 nm via hybrid modes based on the modal strong coupling between the plasmons of Au-NPs and the FP nanocavity of NiO on a Pt film. All wavelength regions of the hybrid modes of the modal strong coupling system promoted hot-hole injection from the Au-NPs to NiO and proton/water reduction by hot electrons. The incident photon-to-current efficiency based on H-2 evolution through water/proton reduction by hot electrons reached 0.2 % at 650 nm and 0.04 % at 800 nm.

The Bi2Te3/Sb2Te3 in-plane heterostructure is reported as a low-dimensional tunable chalcogenide well suited as plasmonic building block for the visible−UV spectral range. Electron-driven plasmon excitations of low-dimensional Bi2Te3/Sb2Te3 are investigated by monochromated electron energy loss spectroscopy spectrum imaging. To resolve the nanoscale spatial distribution of various local plasmonic resonances, singular value decomposition is used to disentangle the spectral data and identify the individual spectral contributions of various corner, edge, and face modes. Furthermore, defect-plasmon interactions are investigated both for nanoscale intrinsic and thermally induced extrinsic polygonal defects (in situ sublimation). Signature of defect-induced red shift ranging from a several hundreds of millielectronvolts to a few electronvolts, broadening of various plasmon response, together with selective enhancement and significant variations in their intensity are detected. This study highlights the presence of a heterointerface and identifies defects as physical tuning pathways to modulate the plasmonic response over a broad spectral range. Finally, the experimental observations are compared qualitatively and validated with numerical simulations using the electron-driven discrete dipole approximation. Low-dimensional Bi2Te3/Sb2Te3 as a less explored plasmonic system holds great promises as emerging platform for integrated plasmonics. Furthermore, introducing controlled structural defects can open the door for nanoengineering of plasmonic properties in such systems., This article also appears in Hot Topic: Surfaces and Interfaces.

An improvement in random lasers based on a colloidal quantum dot (QD)/graphene-doped polymer was observed and attributed to multiple light-scattering and graphene surface plasmon resonance. The emission characteristics of quantum dots doped with graphene oxide and reduced graphene oxide were compared. The QD/reduced graphene oxide hybrid exhibited a lower laser emission threshold (~460 µJ/cm2). The emission modes and thresholds were strongly dependent on both the graphene doping concentration and the external temperature. Decreased plasmon coupling was the primary reason for lower QD/graphene laser emission with increasing temperature. The optimum reduced graphene oxide concentration was 0.2 wt.%. This work provides a practical approach to optimizing the threshold and stability of random laser devices, with potential applications in displays, sensors, and anti-counterfeiting labels. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

Understanding biomolecular interactions and cellular activities based on these interactions are important research topics in bioanalytical chemistry that can have a large impact on key fields such as drug discovery, biomedical sciences, and environmental monitoring. High performing biosensors are an essential part for this task. Effective sensing platforms with improved analytical performance and reduced cost are actively sought after and remain a major area of intense research endeavors. The goal of this thesis is to develop novel biosensing systems enabled by 3D printing technology and nanoscience for probing biochemical interactions and achieving cell lipidomic analysis.Surface plasmon resonance (SPR) biosensors have been wildly applied for biomolecular assays in a label-free fashion. The sensitivity of SPR sensors, however, still needs signal enhancement when dealing with trace amounts of analytes. Chapter 2 describes the fabrication and application of gold nanoparticles-coupled POPC liposomes nanoclusters for signal amplification for SPR sensors and the study of protein-membrane recognition on a biomimetic interface. By combining the large mass of liposomes and plasmonic coupling of the noble metal nanoparticles, the highly stable POPC-gold nanoparticles showed a large amplification effect and a 0.1 ng/mL LOD was achieved for cholera toxin detection. 3D printing technology has greatly impacted the bioanalytical fields by providing the fabrication capability with almost no geometric restriction, rapid prototyping, and low cost. Chapter 3 describes the design and fabrication of a Dove prism by 3D printing with transverse micropatterns for multiplexed sensing with SPR imaging. The sensitivity of the system was evaluated by bulk refractive index change and protein binding assays; both showed similar performance as compared to the SPR configuration using high end glass optics. 3D printing technology has been further applied to fabricating microfluidic chips for cell

To date, photoanodes containing bimetallic alloy nanoparticles (ANPs) are exposed good photoelectrochemical (PEC) performance for hydrogen production owing to their optoelectronic properties. In this work, low-cost, visible light active and environmental-friendly BiVO4/Bi-Cu nanocomposite photoanode is fabricated via organic decomposition and electrodeposition process. Transmission electron microscope images reveals that Bi-Cu ANPs are uniformly distributed on BiVO4 which can enhance the PEC performance. Typical results originate that BiVO4/Bi-Cu nanocomposite exhibits a high photocurrent density of 10.31 mA cm-2 at 1.23 V and solar-to-hydrogen conversion efficiency of 3.55%, which is higher than other electrodes. In addition, this composite shows excellent long-term stability over 5 h and low charge transfer resistance. These results suggest the introduction of Bi-Cu ANPs enhances the broadband light absorption of BiVO4 due to the excitation of localized surface plasmons at different wavelengths and also improves the charge transportation in the photoanode. Thus, BiVO4/Bi-Cu photoelectrode reports here is superior PEC performance for hydrogen generation providing an economical and feasible route to fabricate surface plasmon resonance (SPR)-enhanced composites as photocatalysts using earth-abundant Bi and Cu metals instead of noble-metals.

To date, photoanodes containing bimetallic alloy nanoparticles (ANPs) are exposed good photoelectrochemical (PEC) performance for hydrogen production owing to their optoelectronic properties. In this work, low-cost, visible light active and environmental-friendly BiVO4/Bi-Cu nanocomposite photoanode is fabricated via organic decomposition and electrodeposition process. Transmission electron microscope images reveals that Bi-Cu ANPs are uniformly distributed on BiVO4 which can enhance the PEC performance. Typical results originate that BiVO4/Bi-Cu nanocomposite exhibits a high photocurrent density of 10.31 mA cm-2 at 1.23 V and solar-to-hydrogen conversion efficiency of 3.55%, which is higher than other electrodes. In addition, this composite shows excellent long-term stability over 5 h and low charge transfer resistance. These results suggest the introduction of Bi-Cu ANPs enhances the broadband light absorption of BiVO4 due to the excitation of localized surface plasmons at different wavelengths and also improves the charge transportation in the photoanode. Thus, BiVO4/Bi-Cu photoelectrode reports here is superior PEC performance for hydrogen generation providing an economical and feasible route to fabricate surface plasmon resonance (SPR)-enhanced composites as photocatalysts using earth-abundant Bi and Cu metals instead of noble-metals.

We developed a photoanode consisting of Au-Ag alloy nanoparticles (NPs), a TiO2 thin film and a Au film (AATA) under modal strong coupling conditions with a large splitting energy of 520 meV, which can be categorized into the ultrastrong coupling regime. We fabricated a photoanode under ultrastrong coupling conditions to verify the relationship between the coupling strength and photoelectric conversion efficiency and successfully performed efficient photochemical reactions. The AATA photoanode showed a 4.0 % maximum incident photon-to-current efficiency (IPCE), obtained at 580 nm, and the internal quantum efficiency (IQE) was 4.1 %. These results were attributed to the high hot-electron injection efficiency due to the larger near-field enhancement and relatively negative potential distribution of the hot electrons. Furthermore, hybrid mode-induced water oxidation using AATA structures was performed, with a Faraday efficiency of more than 70 % for O-2 evolution.

We developed a photoanode consisting of Au-Ag alloy nanoparticles (NPs), a TiO2 thin film and a Au film (AATA) under modal strong coupling conditions with a large splitting energy of 520 meV, which can be categorized into the ultrastrong coupling regime. We fabricated a photoanode under ultrastrong coupling conditions to verify the relationship between the coupling strength and photoelectric conversion efficiency and successfully performed efficient photochemical reactions. The AATA photoanode showed a 4.0 % maximum incident photon-to-current efficiency (IPCE), obtained at 580 nm, and the internal quantum efficiency (IQE) was 4.1 %. These results were attributed to the high hot-electron injection efficiency due to the larger near-field enhancement and relatively negative potential distribution of the hot electrons. Furthermore, hybrid mode-induced water oxidation using AATA structures was performed, with a Faraday efficiency of more than 70 % for O-2 evolution.

Collective optoelectronic phenomena such as plasmons and phonon polaritons can drive processes in many branches of nanoscale science. Classical physics predicts that a perfect thermal emitter operates at the black body limit. Numerous experiments have shown that surface phonon polaritons allow emission two orders of magnitude above the limit at a gap distance of ≈50 nm. This work shows that a supported multilayer graphene structure improves the state of the art by around one order of magnitude with a ≈1129-fold-enhancement at a gap distance of ≈55 nm. Coupled surface plasmon polaritons at mid- and far-infrared frequencies allow for near-unity photon tunneling across a broad swath of k-space enabling the improved result. Electric tuning of the Fermi-level allows for the detailed characterization and optimization of the colossal nanoscale heat transfer., QC 20220517

It is well-known that a quantum of light (photon) has a zero mass in vacuum. Entering into a medium the photon creates a quasiparticle (polariton, plasmon, surface-phonon, surface-plasmon polariton, etc.) whose rest mass is generally not zero. In this letter, devoted to the memory of Mark Stockman, we evaluate the rest mass of light-induced surface-plasmon polaritons (SPPs) and discuss an idea that collisions of two massive SPP quasiparticles can result in changes of their frequencies according to the energy and momentum conservation laws. © 2021 Nikolai B. Chichkov et al., published by De Gruyter, Berlin/Boston.

A plasmonic sensing platform was developed as a noninvasive method to monitor gas-phase biomarkers related to cystic fibrosis (CF). The nanohole array (NHA) sensing platform is based on localized surface plasmon resonance (LSPR) and offers a rapid data acquisition capability. Among the numerous gas-phase biomarkers that can be used to assess the lung health of CF patients, acetaldehyde was selected for this investigation. Previous research with diverse types of sensing platforms, with materials ranging from metal oxides to 2-D materials, detected gas-phase acetaldehyde with the lowest detection limit at the µmol/mol (parts-per-million (ppm)) level. In contrast, this work presents a plasmonic sensing platform that can approach the nmol/mol (parts-per-billion (ppb)) level, which covers the required concentration range needed to monitor the status of lung infection and find pulmonary exacerbations. During the experimental measurements made by a spectrometer and by a smartphone, the sensing examination was initially performed in a dry air background and then with high relative humidity (RH) as an interferent, which is relevant to exhaled breath. At a room temperature of 23.1 °C, the lowest detection limit for the investigated plasmonic sensing platform under dry air and 72% RH conditions are 250 nmol/mol (ppb) and 1000 nmol/mol (ppb), respectively.

As a key industrial nitrogenous product and a critical environmental pollutant, ammonia broadly affects our daily lives. Rapid and sensitive detection of ammonia is essential to both environmental monitoring and process control for industrial manufacturing. Here, we present a protocol for rapid detection of low amounts of ammonia in the aqueous phase, via surface-enhanced Raman spectroscopy. We believe the mechanism and speed of the approach demonstrate its potential toward applications in operando electrochemical catalysis and in situ ammonia detection. For complete details on the use and execution of this protocol, please refer to Liu et al. (2020).

Enhancing photoluminescence (PL) of semiconducting 2D materials is proven essential for many applications related to optoelectronics and sensing. Here, we demonstrate synergistic PL enhancement in 2D materials by incorporating silver plasmonic nanodiscs in defect-induced monolayer molybdenum disulfide (MoS2) for luminescent quench sensing of dopamine with high accuracy and selectivity. We develop a hole-array perforated 2D MoS2 embedded with plasmonic silver dimers to harmonize the surface plasmon resonance with the PL wavelength of monolayer MoS2, which enhance it by 56-fold. We implemented the optimized perforated MoS2/dimers platform as a catalytic assay for on-chip PL quenching detection of dopamine, achieving a low limit of detection of 9.3 nM. This approach opens avenues of high-performance molecular sensing applications by improving the PL emission of 2D materials.

Sunlight-powered reduction of CO2 to fuels and chemicals is a promising strategy to close the carbon loop and facilitate the energy transition. In this research, we demonstrate that Au nanoparticles supported on TiO2 are an efficient plasmonic catalyst for the sunlight-powered reverse water-gas shift (rWGS) reaction. A maximum CO production rate of 429 mmol ⋅ gAu−1 ⋅ h−1 with a selectivity of 98 % and an apparent quantum efficiency of 4.7 % were achieved using mildly concentrated sunlight (1.44 W ⋅ cm−2 equals 14.4 sun). The CO production rate showed an exponential increase with increasing light intensity, suggesting that the process is mainly promoted by a photothermal effect. Thermal reference experiments with the same catalysts promoted CH4 formation, dropping the CO selectivity to 70 %. Thus, mildly concentrated sunlight can efficiently and selectively enhance the promotion of the rWGS reaction without using external heating., ImPhys/Optics

This paper investigates the photocatalytic characteristics of Ag nanowire (AgNW)/TiO2 and AgNW/TiO2/graphene oxide (GO) nanocomposites. Samples were synthesized by the direct coating of TiO2 particles on the surface of silver nanowires. As-prepared AgNW/TiO2 and AgNW/TiO2/GO nanocomposites were characterized by electron microscopy, X-ray diffraction, UV/visible absorption spectroscopy, and infrared spectroscopy. Transmission electron microscope (TEM) images confirmed the successful deposition of TiO2 nanoparticles on the surface of AgNWs. The photocatalytic activity of synthesized nanocomposites was evaluated using Rhodamine B (RhB) in an aqueous solution as the model organic dye. Results showed that synthesized AgNW/TiO2/GO nanocomposite has superior photocatalytic activities when it comes to the decomposition of RhB., Electronic Components, Technology and Materials

Sunlight-powered reduction of CO2 to fuels and chemicals is a promising strategy to close the carbon loop and facilitate the energy transition. In this research, we demonstrate that Au nanoparticles supported on TiO2 are an efficient plasmonic catalyst for the sunlight-powered reverse water-gas shift (rWGS) reaction. A maximum CO production rate of 429 mmol ⋅ gAu−1 ⋅ h−1 with a selectivity of 98 % and an apparent quantum efficiency of 4.7 % were achieved using mildly concentrated sunlight (1.44 W ⋅ cm−2 equals 14.4 sun). The CO production rate showed an exponential increase with increasing light intensity, suggesting that the process is mainly promoted by a photothermal effect. Thermal reference experiments with the same catalysts promoted CH4 formation, dropping the CO selectivity to 70 %. Thus, mildly concentrated sunlight can efficiently and selectively enhance the promotion of the rWGS reaction without using external heating.