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Controlling composition and plasmonic response of bimetallic nanoparticles (NPs) is of great relevance to tune their catalytic activity. Herein, we demonstrate reversible composition and plasmonic response transitions from a core/shell to a bimetallic alloyed palladium/gold NP triggered by CO adsorption and sample temperature. The use of self-organized growth on alumina template film allows scrutinizing the impact of core size and shell thickness onto NP geometry and plasmonic response. Topography, molecular adsorption, and plasmonic response are addressed by scanning tunneling microscopy, vibrational sum frequency generation (SFG) spectroscopy, and surface differential reflectance spectroscopy, respectively. Modeling CO dipolar interaction and optical reflectivity corroborate the experimental findings. We demonstrate that probing CO adsorption sites by SFG is a remarkably sensitive and relevant method to investigate shell composition and follow in real-time Pd atom migration between the core and the shell. Pd–Au alloying is limited to the first two monolayers of the shell and no plasmonic response is found, while for a thicker shell, a plasmonic response is observed, concomitant with a lower Pd concentration in the shell. Above 10−4 mbar, at room temperature, CO adsorption triggers the shell restructuration, forming a Pd–Au alloy that weakens the plasmonic response via Pd migration from the core to the shell. NP annealing at 550 K, after pumping CO, leads to the desorption of remaining CO and gives enough mobility for Pd to migrate back inside the core and recover a pure gold shell with its original plasmonic response. This work demonstrates that surface stoichiometry and plasmonic response can be tuned by using CO adsorption and NP annealing. [ABSTRACT FROM AUTHOR]

Colloidal solutions of gold nanorods and silver-coated gold nanorods were prepared. The seeded growth synthesis protocols were improved by adding a flocculation purification step. The resulting populations of pure gold nanorods and Au@Ag core–shell cuboids were characterized by very low dispersion in size and shape. UV–vis–near-infrared absorption measurements were performed on several batches of well-calibrated nano-objects, supported by calculations based on the discrete dipole approximation, allowed to highlight the impact of various morphological features on the optical response. In addition to the well-known effect of the nanorod aspect ratio on the shift of the longitudinal surface plasmon resonance mode, special attention was paid to changing either the rounding of the nanorod end-caps or that of the edges of the coating silver shell. Nanorods and cuboids were modeled as superellipsoids. This approach enabled us to model precisely their complex shapes using just a few simple parameters and analyze the evolution of their extinction spectra as a function of the rounding of their tips and edges. Such nano-objects are widely used for various applications in fields such as biomedical, biosensing, or surface-enhanced Raman spectroscopy, thus making it crucial to precisely assess the impact of each morphological feature for optimizing their performance. [ABSTRACT FROM AUTHOR]

With advantages such as low cost, high stability, and ease of production, visible light photocatalytic C3N4 with a unique microscopic layered structure holds significant potential for development. However, its hydrogen production efficiency remains low due to the pronounced recombination of photo-generated charge carriers and limited surface reaction sites. Normally, the photocatalytic performance of C3N4 can be enhanced by loading noble metals with surface plasmon resonance. It is worth noting that the size of noble metal nanoparticles has a great influence on photocatalytic performance. In this study, accurate controlling of the size and distribution of Au nanoparticles was achieved on the surface of C3N4 by introducing amino groups to improve photocatalytic performance. Results show that uniformly distributed Au nanoparticles in the range of 2–6 nm can be obtained on C3N4 with a remarkable enhancement of hydrogen production efficiency, which is about 114 times the property of pure C3N4. The small-sized and uniformly distributed Au nanoparticles can provide more reaction sites and increase the separation of photo-generated charge carriers, in turn improving Au/NH3–C3N4 photocatalytic hydrogen release rate to 6.85 mmol g−1 h−1. This work offers a facile way to enhance photocatalytic performance by controlling the size of metal nanoparticles on C3N4 precisely. [ABSTRACT FROM AUTHOR]

Nanostructures possessing plasmonic and magnetic properties can enhance the transverse magneto-optical Kerr effect (TMOKE) by exciting surface plasmon resonances (SPRs). This provides a promising platform for magneto-optical SPR sensors with significantly improved sensing performance. Here, we propose a high-performance magneto-optical SPR sensor, which consists of a bilayer Au/Co grating placed on a gold film. By tuning the structural parameters, a Fano-like TMOKE spectrum with a linewidth of only 0.0135 nm and an amplitude approaching the theoretical maximum is obtained. We attribute the optimal TMOKE signal achieved by the sensor to the critical coupling concept which is associated with the trade-off between scattering and intrinsic decay rates of the system. The optimized nanostructure sensor demonstrates a sensitivity of 1432 nm/RIU to refractive index fluctuations as small as 0.0001 in air, and all figures of merit (FOM) up to 105 RIU−1, making it suitable for gas sensor fabrication. [ABSTRACT FROM AUTHOR]

In 3D-deposited AgNW/TiO2, which is prepared by spray-applying titanium dioxide suspension to deposited silver nanowire sheets, the synergistic effects of increased crossing points of AgNWs to enhance localized surface plasmon resonance excitation and longer-lived electrons in the conduction band of TiO2 generated by plasmon-induced charge transfer have successfully resulted in photocatalytic activity in the visible light range. We have developed photocatalytic sheets in which TiO2 particles are uniformly attached to 3D-deposited AgNWs. Regarding the prepared sheet, it was confirmed that TiO2 was indeed well adhered to the AgNWs, and electron transfer was efficient at the interface. This sheet solves the problem that the response wavelength range of the photocatalytic reaction using TiO2 is only in the ultraviolet region and exhibits sufficient photocatalytic effect in the visible light region. Transient absorption spectroscopy measurements in the diffuse reflectance configuration confirmed that the electrons of AgNWs actually move into the conduction band of TiO2 under visible light and that the interaction is independent of the excitation light intensity, thereby extending the lifetime of the electrons. [ABSTRACT FROM AUTHOR]

Hyperbolic metasurfaces exhibit unique dispersion and polarization properties, making them a promising platform for a plethora of photonic applications. At the same time, the ability to engineer the hyperbolicity via the predefined spectral positions of the metasurface resonances remains a notable challenge. Here, we analyze the dependencies of the spectral positions of the resonances corresponding to the limits of the hyperbolic regime for the metasurfaces based on square arrays of the rectangular nanopatches. We show that the spectral difference between the resonances increases linearly with stretching of the nanopatch, but this dependence becomes quadratic when the length of the stretched nanopatch exceeds 85% of the lattice constant, indicating the regime of extreme anisotropy. Finally, we demonstrate the characteristic feature of the engineered resonances by showing the canalization (divergenceless propagation) of the surface plasmon-polariton along the anisotropic nanopatch-based metasurface in the vicinity of the resonance. The results obtained may be used for the engineering of the anisotropic nanoparticle-based metasurfaces for a plethora of photonic applications. [ABSTRACT FROM AUTHOR]

The integration of Au nanorods in tip-enhanced Raman spectroscopy (TERS) presents a significant increase in the enhancement factor, primarily due to the gap-mode effect. By aligning Au nanorods in parallel, we construct an Au nanorod lattice, referred to as the Au nanolattice, which further amplifies the advantages of TERS imaging due to the induced inter-nanorod surface plasmon resonance. A critical aspect in this research involves investigating the distribution of hotspots within the nanolattice during TERS measurements. Additionally, we demonstrate that the tip–lattice nanocavity is a predominant factor in determining both the intensity and spatial distribution of these hotspots. Employing the experimental and simulation results, we illustrate the enhancement effect of the tip–lattice cavity and elucidate the connection between the hotspot intensity and cavity size. This comprehensive approach contributes to our understanding of the nano-lattice's role in TERS and offers valuable insights for optimizing nanophotonic applications. [ABSTRACT FROM AUTHOR]

The surface plasmon resonance (SPR) technique has been widely applied to biosensing technologies for the rapid quantification of biomolecules without enzyme and fluorescent labeling. However, the conventional prism-coupling SPR method generally has a detection area of a few mm2, and the large contribution of the background signal forms a barrier to highly sensitive detection. Based on a highly spatially resolved SPR method, the present study constructed a scanning GC-SPR imaging instrument using an objective lens with a high numerical aperture and a plasmonic chip that could be used for grating-coupled SPR. Focusing light on the diffraction limit can suppress background signals and improve detection sensitivity. SPR imaging can also be performed by scanning a focal spot. Using this method, the refractive index of a mixture of water and dimethyl sulfoxide was measured with a detection accuracy of 2.43 × 10−3 RIU. Polydopamine films prepared with a thickness of <5 nm were also measured, and each film thickness was evaluated with high sensitivity from the effective refractive index detected in a small area of <1 µm2. [ABSTRACT FROM AUTHOR]

One-dimensional plasmonic nanogratings (1D-PNGs) with high aspect ratios and narrow grooves promise enhanced coupling for hybrid graphene systems with the localized surface plasmon of the metallic grating and graphene surface plasmons. However, both the fabrication of the 1D-PNG and the application of graphene to it are difficult. We developed 1D-PNGs with a high aspect ratio of 15 and narrow grooves of 100 nm in width using the tapered mold method and a dry graphene-transfer procedure. Raman spectroscopy measurements showed that monolayer graphene was successfully transferred onto the 1D-PNGs, and the graphene was strongly doped with Au in the 1D-PNGs. Graphene on narrow grooves (free-standing graphene) demonstrated an almost identical p-doping level to graphene on Au because the narrow groove width allowed sufficient doping by Au for graphene on grooves. Reflectance measurements showed that the 1D-PNGs exhibited polarization- and wavelength-selective absorption at infrared (IR) wavelengths, and the effect of graphene blue-shifted the absorption peak wavelength induced by the surface plasmon resonance of 1D-PNGs. Numerical calculations agree well with these experimental results and indicate that the electric field strongly localizes on graphene in the grooves. Moreover, the doping level tunes the absorption wavelength owing to the coupling with graphene plasmons and the surface plasmon resonance of 1D-PNGs. This could provide electrical tunability to the graphene plasmons. Our fabrication procedure produced hybrid graphene-1D-PNGs with high aspect ratios and narrow groove systems for IR wavelengths. This system can contribute to developing high-performance electrically tunable graphene-based IR photodetectors, tunable IR emitters/absorbers, and biological sensors. [ABSTRACT FROM AUTHOR]

The plasmonic coupling between silver (Ag) and gold (Au) nanoparticles (NPs) under four polarization modes was examined: a longitudinal mode (L-mode), where the electric field of a linearly polarized incident light parallels the dimer axis, and three transverse modes (T-modes), where the electric field of the light is perpendicular to the dimer axis. The coupling was studied using the discrete dipole approximation followed by an in-house postprocessing code that determines the extinction (Qext), absorption (Qabs), and near-field (Qnf) spectra from the individual NPs as well as the whole system. In agreement with the literature results, the extinction/absorption spectra of the whole dimer have two peaks, one near the Ag localized surface plasmon resonance (LSPR) region and the other at the Au LSPR region, with the peak at Ag LSPR being reduced in all modes and the peak at Au LSPR being red-shifted and increased in the L-mode but not in the T-modes. It is further shown that the scattering at the Ag LSPR region is reduced and becomes less than the isolated Ag NPs, but the absorption at the Ag LSPR is increased and becomes greater than the isolated Ag NPs for the 50 nm Ag–Au heterodimer. This suggests that the scattering from Ag NPs is being reabsorbed by the neighboring Au NPs due to the interband electronic transition in Au at that wavelength range. The Qext from the individual NP in the heterodimer shows the presence of the Fano profile on the Au NP but not on the Ag NP. This phenomenon was further investigated by using a dielectric particle (DP) placed near the Ag or Au NPs. The Fano profile appears in the absorbing DP spectra placed near either Ag or Au NPs. However, the Fano profile is masked upon further increases in the refractive index value of the DP particle. This explains the absence of a Fano profile on the Ag NPs in the Ag–Au heterodimer. The large near-field enhancement on both Ag and Au NPs at the Au plasmonic wavelength in the L-mode for large NPs was investigated through a DP-Au system. The large enhancement was shown to arise from a large imaginary component of the DP refractive index and a small real component. Through examination of both the near- and far-field properties of the individual NPs as well as the whole system and examinations of DP-Ag and DP-Au systems, our study provides a new understanding of the couplings between Ag and Au NPs. [ABSTRACT FROM AUTHOR]

Core–shell gold–silver cuboidal nanoparticles were produced, with either concave or straight facets. Their incubation with a low concentration of chiral l-glutathione (GSH) biomolecules was found to produce near UV plasmonic extinction and induced circular dichroism (CD) peaks. The effect is sensitive to the silver shell thickness. The GSH molecules were found to cause redistribution of silver in the shell, removing silver atoms from edges/corners and re-depositing them at the nanocuboid facets, probably through some redox and complexation processes between the silver and thiol group of the GSH. Other thiolated chiral biomolecules (and drug molecules) did not show this effect. The emerging near UV surface plasmon resonance is a silver slab resonance, which might also possess some multipolar resonance nature. The concave-shaped nanocuboids exhibited stronger induced plasmonic CD relative to the nanocuboids with straight facets. [ABSTRACT FROM AUTHOR]

As one of the most widely used infrared (IR) detectors, a mercury cadmium telluride (MCT) detector usually requires liquid nitrogen refrigeration to suppress thermally activated noise mechanisms that are inherent to its narrow bandgap, which limits its practical applications. Therefore, it is essential to develop strategies to suppress dark current with reduced cooling demand. In this work, a surface plasmon resonance (SPR) enhanced MCT microcavity was proposed to intensify optical absorption across a broadband while diminishing the thickness of the MCT layer to reduce intrinsic dark current proportional to the volume of the absorber. The microcavity is formed by sandwiching the MCT layer between a top well-designed hybrid golden-cross antenna array and a bottom golden reflector. The microcavity is employed to trap the incident light to amplify the absorption, and the golden-cross antenna array is introduced to not only significantly enhance the incident light field through the SPR effect but also to broaden the microcavity resonant mode. Numerical calculation indicated that an absorptance exceeding 95.3% can be attained at 3.4 μm with the full width at half maxima (FWHM) extending beyond 1.38 μm, which almost covers the absorption band of MCT in mid-wavelength IR (MWIR), all while the MCT layer is only 530 nm. Moreover, the prototype device unit was fabricated and tested. Measured peak absorption reached 98.7% @ 3.6 μm and FWHM was as broad as 1.12 μm. These results demonstrate that the high and wideband absorption in an ultrathin MCT layer is achieved based on the synergistic effects of SPR and microcavity resonance. [ABSTRACT FROM AUTHOR]

Efficient absorption of solar radiation holds the key to photothermal utilization; however, realizing solar absorber designs with high absorption efficiency remains challenging. Herein, a nickel-based metamaterial selective solar absorber with a nanopillar array structure was proposed to realize nearly perfect optical absorption over a broad spectrum. The average absorbance is up to 96% in the 300–2033 nm wavelength range. Notably, a reasonably detailed analysis of the physical mechanism of the proposed absorber was performed in this paper, attributing the exceptional broadband absorption to the concurrent interaction with surface plasmon resonance, quarter-wavelength resonance, and electric dipole resonance. The absorption efficiency declines significantly when λ > 2.5 μm, with only 20% absorptivity at λ = 6 μm in the radiation-absorbing transition region. This decline is desirable, as it contributes to reducing the emissivity in the mid-infrared range and, therefore, prevents self-radiation. The results demonstrate that the selective absorber possesses the potential to capture solar energy within a broadband, while avoiding undesirable self-radiation, thereby enhancing the integral efficiency of the solar energy conversion system. Moreover, the absorption spectrum shows insensitivity to polarization and angle of incidence. The selective solar absorber proposed here offers excellent performance with a simple structure, showing great promise in the field of photothermal conversion. [ABSTRACT FROM AUTHOR]

We investigate the potential of surface plasmon polaritons at noble metal interfaces for surface-enhanced chiroptical sensing of dilute chiral drug solutions with nl volume. The high quality factor of surface plasmon resonances in both Otto and Kretschmann configurations enables the enhancement of circular dichroism differenatial absorption thanks to the large near-field intensity of such plasmonic excitations. Furthermore, the subwavelength confinement of surface plasmon polaritons is key to attain chiroptical sensitivity to small amounts of drug volumes placed around ≃100 nm by the metal surface. Our calculations focus on reparixin, a pharmaceutical molecule currently used in clinical studies for patients with community-acquired pneumonia, including COVID-19 and acute respiratory distress syndrome. Considering realistic dilute solutions of reparixin dissolved in water with concentration ≤ 5 mg/ml and nl volume, we find a circular-dichroism differential absorption enhancement factor of the order ≃20 and chirality-induced polarization distortion upon surface plasmon polariton excitation. Our results are relevant for the development of innovative chiroptical sensors capable of measuring the enantiomeric imbalance of chiral drug solutions with nl volume. [ABSTRACT FROM AUTHOR]

[Display omitted] The present paper reports the fabrication of novel types of hybrid fibrous photocatalysts by combining block copolymer (BCP) templating, sol–gel processing, and coaxial electrospinning techniques. Coaxial electrospinning produces core–shell nanofibers (NFs), which are converted into hollow porous TiO 2 NFs using an oxidative calcination step. Hybrid BCP micelles comprising a single plasmonic nanoparticle (NP) in their core and thereof derived silica-coated core–shell particles are utilized as precursors to generate yolk-shell type particulate inclusions in photocatalytically active NFs. The catalytic and photocatalytic activity of calcined NFs comprising different types of yolk-shell particles is systematically investigated and compared. Interestingly, calcined NFs comprising silica-coated yolk-shells demonstrate enhanced catalytic and photocatalytic performance despite the presence of silica shell separating plasmonic NP from the TiO 2 matrix. Electromagnetic simulations indicate that this enhancement is caused by a localized surface plasmon resonance and a confinement effect in silica-coated yolk-shells embedded in porous TiO 2 NFs. Utilization of the coaxially electrospun TiO 2 NFs in combination with yolk-shells comprising plasmonic NPs reveals to be a potent method for the photocatalytic decomposition of numerous pollutants. It is worth noting that this study stands as the first occurrence of combining yolk-shells (Au@void@SiO 2) with porous electrospun NFs (TiO 2) for photocatalytic purposes and gaining an understanding of plasmon and confinement effects for photocatalytic performance. This approach represents a promising route for fabricating highly active and up-scalable fibrous photocatalytic systems. [ABSTRACT FROM AUTHOR]

The preparation of histology slides is a critical step in histopathology, and poor-quality histology slides with weak adhesion of tissue sections to the substrate often affect diagnostic accuracy and sometimes lead to diagnostic failure due to tissue section detachment. This issue has been of concern and some methods have been proposed to enhance tissue-substrate adhesion. Unfortunately, quantitative analysis of the adhesion between tissue sections and glass slides is still challenging. In this work, the adhesion of mouse brain tissue sections on gold-coated glass slides was analyzed using a laboratory-fabricated hyperspectral surface plasmon resonance microscopy (HSPRM) system that enabled single-pixel spectral SPR sensing and provided two-dimensional (2D) distribution of resonance wavelengths (RWs). The existence of the nanoscale water gap between the tissue section and the substrate was verified by fitting the RW measured in each pixel using the five-layer Fresnel reflection model. In addition, a 2D image of the tissue-substrate adhesion distance (AD) was obtained from the measured 2D distribution of RWs. The results showed that tissue-substrate AD was 20–35 nm in deionized water and 4–24 nm in saline solution. The HSPRM system used in this work has a wide wavelength range of 400–1000 nm and can perform highly sensitive and label-free detection over a large dynamic detection range with high spectral and spatial resolutions, showing significant potential applications in stain-free tissue imaging, quantitative analysis of tissue-substrate adhesion, accurate identification of tumor cells, and rapid histopathological diagnosis. [ABSTRACT FROM AUTHOR]

Polarization filters based on surface plasmon resonance (SPR) have undergone rapid development in recent years. In this work, a dual D-type PCF polarization filter based on SPR is designed and analyzed. The filter improves the limiting loss of the core mode by gilding the semi-circular split ring and inlaying amethyst. The influence of the structural parameters of the filter on the filtering characteristics is analyzed by the finite element method. The results show that the core mode losses of the x and y polarized light are 32 dB/cm and 910.56 dB/cm at 1.55 μ m, respectively. For a fiber length of 1000 μ m, the crosstalk and bandwidth are 763.11 dB and 700 nm, respectively. In addition, the impact of manufacturing errors in the structural parameters on the filter performance is discussed. The filter has excellent filtering characteristics and large potential in optical communication and optical sensing. [ABSTRACT FROM AUTHOR]

Borophosphate-based glass materials have the potential to revolutionize optical technology because of their outstanding optical properties, long-lasting nature, and cost-effectiveness. The present research addresses the intricate functions of rare earth and metallic nanoparticles (NPs) in borophosphate glass, which have significant potential for optical photonic and medical applications by incorporating Dy3+ ions and Cu NPs. We developed novel hybrid glasses through the melt-quenching technique, which includes the creation of functional groups and the establishment of bonds between P2O5 and B2O3, as confirmed by FTIR and Raman spectroscopy. UV–visible absorption spectra were used to identify the presence of Cu⁺ and Cu (Saeed et al., 2021) [2]⁺ ions and Cu nanoparticles, with the absorption peaks indicating their respective states. Furthermore, the underlying mechanisms of energy transfer in a glass matrix that is co-doped with dysprosium ions (Dy3+) have been studied. The experimental findings of this research not only provide valuable information about the physical properties of borophosphate glass but also emphasize the collaborative relationship between the rare-earth ion and copper nano-powders. The Tauc plot analysis demonstrated a correlation between the concentration of Cu and Dy dopants and a decrease in the energy band gap of the glass. This suggests that these dopants influence the electronic structure of the glass. This study opens up possibilities for creating innovative photonic materials with customized optical attributes. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: There is an unmet need for compounds to detect fibrillar forms of alpha-synuclein (αSyn) and 4-repeat tau, which are critical in many neurodegenerative diseases. Here, we aim to develop an efficient surface plasmon resonance (SPR)-based assay to facilitate the characterization of small molecules that can bind these fibrils. Methods: SPR measurements were conducted to characterize the binding properties of fluorescent ligands/compounds toward recombinant amyloid-beta (Aβ)42, K18-tau, full-length 2N4R-tau and αSyn fibrils. In silico modeling was performed to examine the binding pockets of ligands on αSyn fibrils. Immunofluorescence staining of postmortem brain tissue slices from Parkinson's disease patients and mouse models was performed with fluorescence ligands and specific antibodies. Results: We optimized the protocol for the immobilization of Aβ42, K18-tau, full-length 2N4R-tau and αSyn fibrils in a controlled aggregation state on SPR-sensor chips and for assessing their binding to ligands. The SPR results from the analysis of binding kinetics suggested the presence of at least two binding sites for all fibrils, including luminescent conjugated oligothiophenes, benzothiazole derivatives, nonfluorescent methylene blue and lansoprazole. In silico modeling studies for αSyn (6H6B) revealed four binding sites with a preference for one site on the surface. Immunofluorescence staining validated the detection of pS129-αSyn positivity in the brains of Parkinson's disease patients and αSyn preformed-fibril injected mice, 6E10-positive Aβ in arcAβ mice, and AT-8/AT-100-positivity in pR5 mice. Conclusion: SPR measurements of small molecules binding to Aβ42, K18/full-length 2N4R-tau and αSyn fibrils suggested the existence of multiple binding sites. This approach may provide efficient characterization of compounds for neurodegenerative disease-relevant proteinopathies. [ABSTRACT FROM AUTHOR]

In this study, the extract obtained from the flowers of the Anchusa azurea (AA) plant was mixed with silver nitrate to obtain silver nanoparticles. The ion sensing ability of the obtained bio-sourced silver nanoparticles in aqueous solutions was investigated and the presence of Hg2+ ions was determined colorimetrically. Silver nanoparticles (AgNPs) prepared on Green Chemistry method, which is both an environmentally friendly and cost-effective synthesis technique, were characterised using different analytical tools. The mean particle size of AA-AgNPs from transmission electron microscopy (TEM) images was determined to be 22 nm in diameter. XRD measurements showed that the crystallite sizes of the synthesised AgNPs were in the face-centred cubic crystal structure with an average size of 22 nm, which is consistent with TEM results. AA-AgNPs showed absorption at 435 nm, indicating that AgNPs exhibit a strong surface plasmon resonance (SPR) and play a role in stabilisation. AgNPs synthesised with Anchusa azurea flowers were observed using UV-vis spectroscopy to selectively and sensitively detect mercury ions (Hg2+). When Hg2+ in aqueous solution was added to the AgNPs, the overall absorbance dramatically decreased and the colour changed from yellow to colourless. This study shows that AA-AgNPs can be used as a cost-effective material in optical sensors for colorimetric determinations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ginsenoside fraction from Panax ginseng decreased the acetylated protein levels of spliceosome in cardiomyocytes. • Ginsenoside Rb2 inhibited SF3A2 acetylation at lysine 10 to promote mitochondrial function against myocardial ischemic/reperfusion injury. • Ginsenoside Rb2 promoted Fscn1 alternative splicing to enhance mitochondrial respiration. • The decreased acetylation of SF3A2 (K 10) by ginsenoside Rb2 was mediated by p300 inhibition. Ginsenosides (GS) derived from Panax ginseng can regulate protein acetylation to promote mitochondrial function for protecting cardiomyocytes. However, the potential mechanisms of GS for regulating acetylation modification are not yet clear. This study aimed to explore the potential mechanisms of GS in regulating protein acetylation and identify ginsenoside monomer for fighting myocardial ischemia-related diseases. The 4D-lable free acetylomic analysis was employed to gain the acetylated proteins regulated by GS pretreatment. The co-immunoprecipitation assay, immunofluorescent staining, and mitochondrial respiration measurement were performed to detect the effect of GS or ginsenoside monomer on acetylated protein level and mitochondrial function. RNA sequencing, site-specific mutation, and shRNA interference were used to explore the downstream targets of acetylation modificationby GS. Cellular thermal shift assay and surface plasmon resonance were used for identifying the binding of ginsenoside with target protein. In the cardiomyocytes of normal, oxygen glucose deprivation and/or reperfusion conditions, the acetylomic analysis identified that the acetylated levels of spliceosome proteins were inhibited by GS pretreatment and SF3A2 acetylation at lysine 10 (K 10) was significantly decreased as a potential target of GS. Ginsenoside Rb2 was identified as one of the active ginsenoside monomers for reducing the acetylation of SF3A2 (K 10), which enhanced mitochondrial respiration against myocardial ischemic injury in in vivo and in vitro experiments. RNA-seq analysis showed that ginsenoside Rb2 promoted alternative splicing of mitochondrial function-related genes and the level of fascin actin-bundling protein 1 (Fscn1) was obviously upregulated, which was dependent on SF3A2 acetylation. Critically, thermodynamic, kinetic and enzymatic experiments demonstrated that ginsenoside Rb2 directly interacted with p300 for inhibiting its activity. These findings provide a novel mechanism underlying cardiomyocyte protection of ginsenoside Rb2 by inhibiting p300-mediated SF3A2 acteylation for promoting Fscn1 expression, which might be a promising approach for the prevention and treatment of myocardial ischemic diseases. [ABSTRACT FROM AUTHOR]

This work presents a novel study on the water-splitting behavior of organic curcumin (C), based on its photoelectrochemical activity. The photodynamics and the kinetics, transfer mechanism, and generation of charges are evaluated for organic curcumin in 0.1 M NaOH electrolyte under visible irradiation. A charge-transfer resistance of 30.03 Ω and induced photocurrent density of 0.9 mA cm−2 are achieved from curcumin nanosheets. The metal-sandwich effect on the kinetics, transfer mechanism, current generation, and potentiodynamics of organic curcumin is explored with Au/C, C/Au, and Au/C/Au photoelectrodes. The Au/C/Au photoelectrodes exhibit extraordinary enhancements in the kinetics, transfer mechanism, current generation, and potentiodynamics, owing to the surface plasmon resonance effect of Au. The Au/C/Au photoelectrode exhibits the lowest charge-transfer resistance of 8.18 Ω and the highest photocurrent density of 3.5 mAcm−2, among the electrodes considered in this work. The obtained photocurrent density of Au/C/Au is 3.9 times higher than that of the pristine organic curcumin photoelectrode. Hence, organic curcumin can be utilized for photoelectrochemical water splitting, instead of the toxic chemicals used in the synthesis of photoelectrodes. [ABSTRACT FROM AUTHOR]

• The isolated anti-CASPR2 antibodies all selectively bind the discoidin domain. • Monoclonal anti-CASPR2 antibodies block the interaction of CASPR2 with contactin 2. • Anti-CASPR2 antibodies cause increased afterpotentials and hyperexcitability in vivo. • Anti-CASPR2 antibodies reduce functional connectivity in resting-state fMRI in vivo. Anti-contactin associated protein receptor 2 (CASPR2) encephalitis is a severe autoimmune encephalitis with a variable clinical phenotype including behavioral abnormalities, cognitive decline, epileptic seizures, peripheral nerve hyperexcitability and neuropathic pain. The detailed mechanisms of how CASPR2 autoantibodies lead to synaptic dysfunction and clinical symptoms are largely unknown. Aiming for analyses from the molecular to the clinical level, we isolated antibody-secreting cells from the cerebrospinal fluid of two patients with CASPR2 encephalitis. From these we cloned four anti-CASPR2 human monoclonal autoantibodies (mAbs) with strong binding to brain and peripheral nerves. All were highly hypermutated and mainly of the IgG4 subclass. Mutagenesis studies determined selective binding to the discoidin domain of CASPR2. Surface plasmon resonance revealed affinities with dissociation constants K D in the pico- to nanomolar range. CASPR2 mAbs interrupted the interaction of CASPR2 with its binding partner contactin 2 in vitro and were internalized after binding to CASPR2-expressing cells. Electrophysiological recordings of rat hippocampal slices after stereotactic injection of CASPR2 mAbs showed characteristic afterpotentials following electrical stimulation. In vivo experiments with intracerebroventricular administration of human CASPR2 mAbs into mice and rats showed EEG-recorded brain hyperexcitability but no spontaneous recurrent seizures. Behavioral assessment of infused mice showed a subtle clinical phenotype, mainly affecting sociability. Mouse brain MRI exhibited markedly reduced resting-state functional connectivity without short-term structural changes. Together, the experimental data support the direct pathogenicity of CASPR2 autoantibodies. The minimally invasive EEG and MRI techniques applied here may serve as novel objective, quantifiable tools for improved animal models, in particular for subtle neuropsychiatric phenotypes or repeated measurements. [ABSTRACT FROM AUTHOR]

This study investigates the potential of energy‐coupling factor (ECF) transporters as promising anti‐infective targets to combat antimicrobial resistance (AMR). ECF transporters, a subclass of ATP‐binding cassette (ABC) transporters, facilitate the uptake of B‐vitamins across bacterial membranes by utilizing ATP as an energy source. Vitamins are essential cofactors for bacterial metabolism and growth, and they can either be synthesized de novo or absorbed from the environment. These transporters are considered promising drug targets, underscoring the need for further research to harness their medicinal potential and develop selective inhibitors that block vitamin uptake in bacteria. Herein, we focused on the ECF transporter for pantothenate (vitamin B5) from Streptococcus pneumoniae and the ECF transporter for folate (vitamin B9) from Lactobacillus delbrueckii as a reference protein. We also included the energizing module for pantothenate along with both full transporter complexes. Initially, we transformed and purified the transporters, followed by an assessment of their thermal stability under various buffer composition, pH, and salt concentrations. Additionally, we monitored the melting temperature over six days to confirm their stability for further assays. We then measured the binding affinities of six ECF inhibitors using surface plasmon resonance (SPR) and evaluated their inhibitory effects through in vitro assays, including bacterial growth assay, whole‐cell uptake, and transport‐activity assays. After determining cytotoxicity in two human cell lines, we established an in vivo infection model using Galleria mellonella larvae to further validate our findings. [ABSTRACT FROM AUTHOR]

The magnetite-silver nanocomposites (Fe3O4-Ag NCs) were synthesized via a facile and green process by Citrus sinensis peel extract. The deposition of silver nanoparticles (NPs) was confirmed by observing an absorption peak at the maximum wavelength at 422 nm in the suspension solution of samples, which is related to silver surface plasmon resonance (SPR). The characteristic diffraction patterns of Fe3O4 and Ag phases were characterized utilizing the XRD patterns and the average size of the crystals was 21 nm. The photocatalytic behavior of Fe3O4-Ag NCs was studied for the destruction of three organic dyes methyl green (MG), methyl orange (MO), and methylene blue (MB) below UV radiation. The effect of the amount of photocatalyst and volume of hydrogen peroxide as an oxidant in the process of dye degradation was also investigated. The complete degradation time of dyes MB, MG, and MO under UV irradiation in the presence of 0.002 g Fe3O4-Ag NCs were 57, 33, and 49 min, respectively. The time of degradation reactions showed the high photocatalytic performance of Fe3O4-Ag NCs. These results proved that the synergistic effect of magnetite in the role of supporting the silver NPs was a significant contribution to the excellent decolorization behavior of Fe3O4-Ag NCs. [ABSTRACT FROM AUTHOR]

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In this research, the meticulous development and exhaustive analysis of molecularly imprinted polymer nanoparticles (nano-MIPs) are explored, with particular emphasis on their affinity for human serum albumin (HSA), a crucial biomarker for diagnosing type 2 diabetes mellitus. The yield of the synthesized nano-MIPs for HSA was determined by a freeze drying technique to be in the range of 6–15 mg for every 100 g of glass beads. A multifaceted characterization approach, including dynamic light scattering analysis, atomic force microscopy, and Fourier-transform infrared spectroscopy, was employed to rigorously assess the physicochemical properties of the nano-MIPs. The results indicate a relatively uniform size distribution and a well-defined chemical composition. Surface plasmon resonance kinetic analysis further revealed that the nano-MIPs exhibit high affinity and specificity for HSA, with a dissociation constant (Kd) of 2.37 × 10−9 M and an R² value of 0.97. These findings not only validate the successful synthesis and characterization of nano-MIPs but also underscore their potential use for selective molecular recognition, thereby providing promising avenues for future research and applications in biomedical and environmental fields. [ABSTRACT FROM AUTHOR]

Tissue injury, including extracellular matrix (ECM) degradation, is a hallmark of group A Streptococcus (GAS) skin infection and is partially mediated by M proteins which possess lectin‐like properties. Hyaluronic acid is a glycosaminoglycan enriched in the cutaneous ECM, yet an interaction with M proteins has yet to be explored. This study revealed that hyaluronic acid binding was conserved across phylogenetically diverse M proteins, mediated by RR/SR motifs predominantly localized in the C repeat region. Keratinocyte wound healing was decreased through the recruitment of hyaluronic acid by M proteins in an M type‐specific manner. GAS strains 5448 (M1 serotype) and ALAB49 (M53 serotype) also bound hyaluronic acid via M proteins, but hyaluronic acid could increase bacterial adherence independently of M proteins. The identification of host–pathogen mechanisms that affect ECM composition and cell repair responses may facilitate the development of nonantibiotic therapeutics that arrest GAS disease progression in the skin. [ABSTRACT FROM AUTHOR]

Photoelectrochemical solar to hydrogen production is a promising way to achieve carbon neutrality, but severe charge recombination in photoanodes limits the conversion efficiency. Herein, Au nanoparticles and Co(OH)x co‐sensitized bismuth vanadate (BiVO4) to construct AuCo(OH)x/BiVO4 photoanode for significantly enhancing the performance of photoelectrochemical water splitting. This process significantly improves the bulk charge carrier separation efficiency, the surface kinetics of water oxidation, and the electron density of BiVO4 photoanode through Au surface plasmon resonance (SPR) and Co(OH)x oxygen evolution catalysts effect. Additionally, the enhancement of the *O and the *OOH generation accelerate the oxygen evolution reaction kinetics. Consequently, the constructed AuCo(OH)x/BiVO4 photoanode demonstrates an excellent photocurrent of 6.2 mA cm−2 at 1.23 V versus reversible hydrogen electrode and a stable continuous output within 42 h. This work contributes to developing high‐efficiency and high‐stability photoanodes for solar H2 production through SPR effect and oxygen evolution catalysts. [ABSTRACT FROM AUTHOR]

Genetic studies have identified the voltage‐gated sodium channel 1.7 (Nav1.7) as pain target. Due to the ineffectiveness of small molecules and monoclonal antibodies as therapeutics for pain, single‐domain antibodies (VHHs) are developed against the human Nav1.7 (hNav1.7) using a novel antigen presentation strategy. A 70 amino‐acid peptide from the hNav1.7 protein is identified as a target antigen. A recombinant version of this peptide is grafted into the complementarity determining region 3 (CDR3) loop of an inert VHH in order to maintain the native 3D conformation of the peptide. This antigen is used to isolate one VHH able to i) bind hNav1.7, ii) slow the deactivation of hNav1.7, iii) reduce the ability of eliciting action potentials in nociceptors, and iv) reverse hyperalgesia in in vivo rat and mouse models. This VHH exhibits the potential to be developed as a therapeutic capable of suppressing pain. This novel antigen presentation strategy can be applied to develop biologics against other difficult targets such as ion channels, transporters and GPCRs. [ABSTRACT FROM AUTHOR]

Objective Methods Results Interpretation Recombinant monoclonal therapeutic antibodies like lecanemab, which target amyloid beta in Alzheimer's disease, offer a promising approach for modifying the disease progression. Due to its relatively short half‐life, lecanemab administered as a bi‐monthly infusion (typically 10 mg/kg) has a relatively brief half‐life. Interaction with abundant plasma proteins binder in the bloodstream can affect pharmacokinetics of drugs, including their half‐life. In this study, we investigated potential plasma protein binding (PPB) interaction to lecanemab using lecanemab biosimilar.Lecanemab biosimilar used in this study was based on publicly available sequences. ELISA and western blotting were used to assess lecanemab biosimilar immunoreactivity in the fractions of human plasma obtained through size exclusion chromatography. The binding of lecanemab biosimilar to candidate plasma binders was confirmed by western blotting, ELISA, and surface plasmon resonance analysis.Using a combination of equilibrium dialysis, ELISA, and western blotting in human plasma, we first describe the presence of likely PPB partners to lecanemab biosimilar and then identify fibrinogen as one of them. Utilizing surface plasmon resonance, we confirmed that lecanemab biosimilar does bind to fibrinogen, although with lower affinity than to monomeric amyloid beta.In the context of lecanemab therapy, these results imply that fibrinogen levels could impact the levels of free antibodies in the bloodstream and that fibrinogen might serve as a reservoir for lecanemab. More broadly, these results indicate that PPB may be an important consideration when clinically utilizing therapeutic antibodies in neurodegenerative disease. [ABSTRACT FROM AUTHOR]

Incorporating noble‐metal plasmonic nanoparticles (NPs) enhances the optoelectronic properties of perovskite solar cells (PSCs) but at a higher cost. In this work, the overlooked potential of refractory plasmonic materials is highlighted as a cost‐effective alternative additive in PSC research. This investigation aims to stimulate interest in this area by showcasing the theoretical and practical impacts of TiN plasmonic NPs when integrated into PSCs. TiN plasmonic NPs present a cost‐effective yet underexplored option. This study explores the impact of TiN NPs on PSCs through theoretical and experimental approaches. Finite‐difference time‐domain (FDTD) optical simulations and empirical data indicate that TiN NPs increase absorption and reduce reflectance in PSCs, driven by surface plasmon resonance and the significant growth of perovskite grains from 450 to 1400 nm. These NPs also regulate the perovskite crystallization rate by adsorbing DMF/DMSO, fostering larger grain formation. Improved band alignment and decreased trap states enhance charge transport and diminish non‐radiative recombination losses. As a result, PSC efficiency with optimal TiN NP concentration increased from 19.07% to 21.37%. Additionally, TiN‐enhanced PSCs display better stability, retaining 98.1% of their original PCE after 31 days under ambient conditions. [ABSTRACT FROM AUTHOR]

Nobel metal nanostructures have been widely studied owing to their excellent surface plasmon resonance (SPR) effects. In order to regulate the SPR properties and applications of noble metal nanostructures, it is critical to accurately control their morphology and composition. Gold nanorods (Au NRs) have become a research hotpot because of their anisotropic shape and tunable plasmonic properties. By designing various heterostructures and assemblies composed of Au NRs, improvements in their SPR effects and further applications can be achieved. In this study, Au NR@Au–Ag nanoframes were prepared based on Au NRs via a sacrificial template method. The combination of metal nanostructures and open nanostructures not only maintained the characteristics of each component, but also showed synergistic effects, enhancing the performance of the composite nanostructures. Experimental results showed that the nanostructures exhibited tunable SPR properties, excellent structural stability and good catalytic activity. Furthermore, a plasmon-induced electromagnetic field enhancement effect greatly enhanced the catalytic activity of the nanostructures. This work provides new ideas and approaches for the design and development of highly active nanocatalysts. [ABSTRACT FROM AUTHOR]

Over the past 10 years, nanotechnology has emerged as a very promising technique for a wide range of biomedical applications. Green synthesized metal and metal oxide nanoparticles (NPs) are cheap, easy to produce in large quantities, and safe for the environment. Currently, efforts are being made to dope ZnO in order to improve its optical, electrical, and ferromagnetic qualities as well as its crystallographic quality. Actually, doping is one of the simplest methods for enhancing an NP's physicochemical characteristics because it involves introducing impure ions into the crystal lattice of the particle. In this study, the biosynthesis of zinc oxide NPs (ZnONPs) and metal‐doped (Mg2+ and Ag+) ZnONPs was carried out by using aqueous and water‐alcoholic extracts of Cynara scolymus L. leaves, Carthamus tinctorius L. flowers, and Rheum ribes L. (RrL) plant, which are rich in phytochemical content. Plant extracts act as a natural reducing, capping, and stabilizing agent in the production. The produced NPs were characterized using a variety of methods, such as ultraviolet‐visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and scanning electron microscopy (SEM). The produced metal‐doped and undoped ZnONPs exhibited characteristic absorption peaks between 365 and 383 nm due to their surface plasmon resonance bands. SEM analysis revealed that the NPs were oval, nearly spherical, and spherical. In the FTIR spectra, the Zn–O bonding peak ranges from 400 to 700 cm−1. The peaks obtained in the range of 407–562 cm−1 clearly represent the Zn–O bond. In addition, the FTIR results showed that there were notable amounts of phenol and flavonoid compounds in both the prepared extract and ZnONPs. According to DLS analysis results, the size distribution of produced NPs is between 120 and 786 nm. The antibacterial properties of green produced NPs on Gram‐positive (Staphylococcus aureus RN4220) and Gram‐negative (Escherichia coli DH10B) bacterial strains were investigated by agar well diffusion method. In studies investigating the anticancer activities of biosynthesized NPs, mouse fibroblast cells (L929) were used as healthy cells and human cervical cancer cells (HeLa) were used as cancer cells. Only the produced Ag‐ZnONPs showed potent dose‐dependent antibacterial activity (at concentrations higher than 100 µg/mL) against Gram‐positive and Gram‐negative bacteria. RrL‐ZnONP‐600 and RrL‐ZnONP‐800 NPs produced with water–ethanol extract of RrL plant and calcined at 600 and 800°C were effective at high concentrations in healthy cells and at low concentrations in HeLa cancer cells, showing that they have the potential to be anticancer agents. The study's findings highlight the potential of green synthesis techniques in the production of medicinal nanomaterials for the treatment of cancer and other biological uses. [ABSTRACT FROM AUTHOR]

ABSTRACT The synergistic influence of the LSPR (localized surface plasmon resonance) of gold nanoparticles (Au NPs) and the effect of nitrogen and chlorine co‐doped carbon dots (Cl/N‐CQDs) on dye‐sensitized solar cells (DSSCs) performance are investigated. The gold NPs are coated with a thin layer of Cl/N‐CQDs to produce the Au@Cl/N‐CQDs structure. DSSCs are fabricated by using Au@Cl/N‐CQDs as co‐sensitizer. The focus of this work is to examine the effects of plasmonic Au NPs and carbon dots in addition to their synergistic effect by capping the Au NPs with Cl/N‐CQDs, and track their influence in DSSCs. N719 as ruthenium‐based dye, and natural dyes including betanin, crocin, carthamin, curcumin, chlorophyll, mallow, and lawsone are selected and applied in the DSSCs co‐sensitized by Au@Cl/N‐CQDs. The power conversion efficiency (PCE) of DSSCs using all of the selected dyes is enhanced upon using the Au@Cl/N‐CQDs. It is due to the improvement in VOC (open circuit voltage) and JSC (short circuit photocurrent densities) relative to the use of dyes alone. Based on computational results, Au@Cl/N‐CQDs cause a red‐shift in comparison with pure dyes. The TD‐DFT (time‐dependent density functional theory) results show that the orbitals from the Au@Cl/N‐CQDs in dye/Au@Cl/N‐CQDs have contribution in most of the absorptions. In other words, electrons from HOMO (highest occupied molecular orbital) of Au@Cl/N‐CQDs is transferred to the LUMO (lowest unoccupied molecular orbital) of dye, in most cases. [ABSTRACT FROM AUTHOR]

Light harvesting materials are crucial for capturing the sunlight in a device such as a solar cell for better efficiency. In this study, we developed high surface area, submicron-sized TiO2 spheres (MTS) incorporated with anisotropic Au nanoparticles (Au_MTS) to create highly light-absorbing photoanodes for enhanced dye-sensitized solar cell (DSSC) efficiency. The high surface area of MTS (~125 m2/g) allows for increased dye-loading, while their submicron size (150-300 nm) provides superior light-scattering capabilities for significantly enhancing the photoanode's light absorption. Furthermore, incorporating of anisotropic Au nanoparticles enables broadband surface plasmon resonance (SPR) coupling, synergistically boosting photon harvesting in the Au_MTS photoanodes. The interconnected tiny TiO2 nanoparticle network in MTS supports charge carrier generation and transport, providing ample sites for dye adsorption and efficient electron pathways. Au_MTS with varying amounts of Au nanoparticles synthesized by a greener microwave-assisted synthesis method and DSSC devices were fabricated and compared with devices made from pristine MTS and P25 nanoparticles. The optimal Au_MTS device, containing ~1.3 wt% Au nanoparticles, achieved a maximum power conversion efficiency (PCE) of ~7.7%, representing improvements of ~40% and ~60% over pristine MTS (PCE of ~5.2%) and P25 nanoparticles (PCE of ~4.71%), respectively. Overall, this work demonstrates the effectiveness of plasmonic mesoporous photoanodes in enhancing DSSC performance through improved photo response, light scattering, and dye loading. [ABSTRACT FROM AUTHOR]

AbstractPolymer-drug interactions play a pivotal role in the design and optimization of drug delivery systems. Thermodynamic principles, such as enthalpy, entropy and free energy, govern these interactions and significantly influence the stability, efficacy and release profiles of the drug-polymer complexes. In this review we explore the role of thermodynamics in drug-polymer binding, focusing on non-covalent interactions, including van der Waals forces, hydrogen bonding, ionic interactions and hydrophobic effects. These interactions affect the drug encapsulation efficiency, release kinetics and the overall stability of the delivery system. Understanding the balance between the various thermodynamic forces helps in the rational design of advanced drug delivery platforms, such as nanoparticles, micelles and hydrogels, which rely on optimized drug-polymer affinity. Our review further delves into the experimental techniques and modeling approaches used to characterize these interactions, such as isothermal titration calorimetry (ITC), molecular dynamics (MD) simulations and surface plasmon resonance (SPR). By examining these thermodynamic foundations, we believe this article provides insights into developing more efficient and stable drug delivery systems that ensure targeted release, enhanced bioavailability and reduced side effects. [ABSTRACT FROM AUTHOR]

This study demonstrates the feasibility of extracting lecithin from oil industry byproducts in an eco‐friendly manner, with minimal use of water and without harmful chemicals. Liposomes can be generated directly from this extracted lecithin, enhancing the value of these byproducts and enabling the production of catalytic gold nanoparticles (AuNPs). Thin‐layer chromatography of the extracted lecithin revealed a phospholipid composition primarily consisting of phosphatidylethanolamine and phosphatidylcholine, and surface tension studies demonstrated similar behavior between the extracted and commercial lecithin. Liposome formation using sustainable lecithin (LPn) resulted in structures that were stable for at least 10 days, exhibiting a low polydispersity index (0.395) and uniform size (approximately 214 ± 7 nm). Gold nanoparticles were synthesized successfully in LPn loaded with [HAuCl4] by using different photoreduction methods: ultraviolet (UV) lamp, pulsed laser 355 nm, and sunlight irradiation. The AuNPs exhibited characteristic sizes (ranging from 5.03 to 6.78 nm) and optical properties typical of nanoparticles, including a distinct surface plasmon resonance. As a proof of concept, we also demonstrated that the synthesized AuNPs exhibited catalytic activity in UV‐induced cis‐trans isomerization reactions. Overall, the study highlights the potential of sustainable soy lecithin extraction for diverse applications, including nanoparticle synthesis and catalysis. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR)-based biosensors have gained increasing prominence due to their ability to provide fast, accurate and real-time results. The functionalization of the SPR sensor chip is essential to ensure the effective binding of recognition biomolecules, making it a crucial step in the efficient construction of biosensors. We demonstrate here the functionalization of the SPR sensor chip with inorganic–organic nanocomposites formed by poly(amidoamine) dendrimers and silver nanoparticles (AgDENs). Several techniques were employed to characterize the structure and morphology of the nanocomposites. Silver nanoparticle/dendrimer structures with a size distribution between 3.7 and 16.2 nm were obtained, and chemical interactions were found between the amide groups of the dendrimers and the silver nanoparticles. Afterward, the synthesized AgDENs were combined with cysteamine using the layer-by-layer (LbL) technique to create multivalent films on the SPR sensor chip. To assess the versatility of these molecular assemblies in the biomaterial anchoring process, studies involving the immobilization of different types of proteins, including the Chaperone CHIP protein (carboxyl terminus of the Hsc70-interacting protein), heat shock cognate protein 70 (Hsc70), Free Candida antarctica lipase B (CALB L), and a recombinant protein (C1 protein) from the protozoan Leishmania infantum to the AgDENs were conducted. To evaluate a specific application, an immunosensor was constructed by anchoring the C1 protein on the proposed platform (AgDENs) to selectively detect Leishmania infantum antibodies in canine serum samples from positive and negative groups for visceral leishmaniasis. In brief, the nanostructured materials composed of poly(amidoamine) dendrimers and silver nanoparticles proved to be effective in anchoring different biological recognition elements, demonstrating their versatility for biosensor applications. An increase in sensor interface sensitivity was observed, likely due to the coupling of localized surface plasmons of silver nanoparticles with the plasmon of the flat Au. The large surface area of the film, combined with its excellent chemical stability, shows that the proposed platform is a very interesting strategy in biosensing. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) proves to be one of the most effective methods of label-free detection and has been integral for the study of biomolecular interactions and the development of biosensors. This trend delves into the latest SPR research and progress built upon the Kretschmann configuration, a pivotal platform, and highlights three key developments that have enhanced the capabilities of the technique. We will first cover a range of explorations of novel plasmonic materials that have shaped SPR performance. Innovative signal transduction and collection, which leverages traditional materials and emerging alternatives, will then be discussed. Finally, the evolving landscape of data analysis, including the integration of machine learning algorithms to navigate complex SPR datasets, will be reviewed. We will also discuss the implementation of these improvements that have enabled new biosensing functions. These advancements not only pave the way for enhanced biosensing in general but also open new avenues for the technique to play a more significant role in research concerning human health. [ABSTRACT FROM AUTHOR]

In this paper, a TMDC-based surface plasmon resonance (SPR) sensor for detecting fat concentration milk, incorporating an Ag-Pt (bimetallic) layer, is presented. The Pt (Platinum) layer provides chemical stability and increases sensitivity with the TMDC layer. Compared to the conventional SPR sensor, the maximum sensitivity, detection accuracy (DA), and figure of merit (FoM) of 314∘/RIU, 0.142/degree, and FoM 44.05/RIU are achieved with the WS2 layer. The sensor's increased sensitivity is due to the increased field intensity and depth of penetration into the sensor layer, resulting in a larger interaction volume. The presence of the WS2 layer, with its significant imaginary part of the dielectric constant, helps improve sensitivity and broadens the SPR curves. This broadening SPR curve ultimately affects the DA and FoM of the sensor. The capability of the proposed sensor to detect various biological analytes with a refractive index (1.3452–1.3657) can be demonstrated. [ABSTRACT FROM AUTHOR]

Gastrointestinal cancer is a common malignant tumor with a high incidence worldwide. Despite continuous improvements in diagnosis and treatment strategies, the overall prognosis of gastrointestinal tumors remains poor. Carcinoembryonic antigen (CEA) is highly expressed in various types of cancers, especially in gastrointestinal cancers, making it a potential target for therapeutic intervention. Therefore, the expression of CEA can be used as an indication of the existence of tumors, chosen as a target for molecular imaging diagnosis, and effectively utilized in the targeted therapy of gastrointestinal cancers. In this study, we report the selection and characterization of affibody molecules (ZCEA539, ZCEA546, and ZCEA919) specific to the CEA protein. Their ability to bind to recombinant and native CEA protein has been confirmed by surface plasmon resonance (SPR), immunofluorescence, and immunohistochemistry assays. Furthermore, Dylight755-labeled ZCEA affibody showed accumulation within the tumor site 1 h post injection and was continuously enhanced for 4 h. The Dylight755-labeled ZCEA affibody exhibited high tumortargeting specificity in CEA+ xenograft-bearing mice and possesses promising characteristics for tumor-targeting imaging. Overall, our results suggest the potential use of ZCEA affibodies as fluorescent molecular imaging probes for detecting CEA expression in gastrointestinal cancer. [ABSTRACT FROM AUTHOR]

Nanotechnology and nanoscience are due to their numerous uses in medicine, engineering, and water pollution sensors and their expanding research fields. In this study, the essential oil, methanolic extract, and biosynthesized silver/silver oxide nanostructures (Ag/AgO NSs) using the aqueous extract of the plant were prepared. The phytochemical compounds of the extract and essential oil were analyzed using gas chromatography/mass spectrometry (GC/MS), respectively. The GC/MS technique identified 34 compounds in the essential oil of the plant with the major constituents including oleic acid (18.5%), palmitic acid (11.08%), phytone (6.64%), p-vinylguaiacol (6.4%), and phytol (4.23%). After the phytochemical identification, the total flavonoid and polyphenol contents of the extract was determined, too. Prodelphinidin B3 compound in the Malva sylvestris extract was analyzed and detected by high-performance liquid chromatography/ultraviolet detector (HPLC-UV), at a retention time of around 10 min. In addition, M. sylvestris extract was used for green synthesis of Ag/AgO NSs. The as-prepared NPs were characterized using X-ray diffraction (XRD), UV-visible absorption spectroscopy, scanning electron microscope equipped with energy-dispersive X-ray spectroscopy (SEM/EDS), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH), and Fourier transform infrared (FT-IR) analyses. Surface plasmon resonance (SPR) absorption at λmax 320 nm in the UV-vis spectra confirms the formation of Ag/AgO NSs. The crystalline structure of Ag/AgO NSs was confirmed by XRD analysis. The nanoparticles were found to have a small size, measuring 64.16 nm, 44.33 nm, and 50 nm using the Williamson-Hall, Scherrer, and SEM/EDS methods, respectively. Besides, that spherical shape of Ag NPs with good size distribution was observed in the SEM/EDS analysis. The small size, around 50 nm, and spherical shape of Ag/AgO NSs with good size distribution were observed in the SEM/EDS analysis. Besides, the antibacterial activity of the extract was evaluated against three pathogenic bacteria, by disk diffusion method. Significant antibacterial activity was observed for the prepared extracts of M. sylvestris against the bacteria (Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa), and the results were compared with the known antibiotics such as amoxicillin, cephalexin, erythromycin, and fluconazole. [ABSTRACT FROM AUTHOR]

To improve anti-icing traits of outdoor coatings, a synergy between photothermal and hydrophobic anti-icings was utilized to fabricate copolymer/Ti3C2Tx MXene composite coatings with good transparency and adhesion. MXene contributes to photothermal trait from local surface plasmon resonance effect. Copolymer enables hydrophobicity from perfluoroalkyls-induced low surface energy and high surface roughness. An increase in MXene dose results in an increased surface roughness. With 140.0 ± 2.2° of water contact angle and 70% of light transmittance, the optimal film bears 2 wt% of MXene. High MXene dose results in large temperature-increase of film under sunlight. After 15 min of sunlight exposure, the temperature of optimal film surface in icing simulation increases from − 18 ℃ to 7.2 ℃. After 48 h of acid immersion, the temperature-increase of optimal film surface based on 300 s of sunlight irradiation reaches 28.7 ± 1.2 ℃. After 48 h of ultraviolet irradiation, the temperature-increase of optimal film surface is 30.7 ± 0.8 ℃. This surface has a water contact angle of 132.7 ± 1.1° after 48 h of acid immersion. This study gives impetus to a preparation of various composite coatings for outdoor anti-icing/deicing. [ABSTRACT FROM AUTHOR]

The RNA binding protein Human Antigen R (HuR) has been identified as a main regulator of the innate immune response and its inhibition can lead to beneficial anti-inflammatory effects. To this aim, we previously synthesized a novel class of small molecules named Tanshinone Mimics (TMs) able to interfere with HuR-RNA binding, and that dampen the LPS-induced immune response. Herein, we present a novel series of TMs, encompassing thiophene 3/TM9 and 4/TM10, furan 5/TM11 and 6/TM12, pyrrole 7b/TM13, and pyrazole 8. The furan-containing 5(TM11) showed the greatest inhibitory effect of the series on HuR-RNA complex formation, as suggested by RNA Electromobility Shift Assay and Time-Resolved FRET. Molecular Dynamics Calculation of HuR − 5/TM11 interaction, quantum mechanics approaches and Surface Plasmon Resonance data, all indicates that, within the novel heteroaryl substituents, the furan ring better recapitulates the chemical features of the RNA bound to HuR. Compound 5/TM11 also showed improved aqueous solubility compared to previously reported TMs. Real-time monitoring of cell growth and flow cytometry analyses showed that 5/TM11 preferentially reduced cell proliferation rather than apoptosis in murine macrophages at immunomodulatory doses. We observed its effects on the innate immune response triggered by lipopolysaccharide (LPS) in macrophages, showing that 5/TM11 significantly reduced the expression of proinflammatory cytokines as Cxcl10 and Il1b. [ABSTRACT FROM AUTHOR]

Intensity-interrogation surface plasmon resonance (I-SPR) provides the fastest imaging speed among various SPR techniques, including wavelength, phase, and angle-based detection. It also integrates easily with other devices and has substantial practical application potential. However, I-SPR's reliance on direct detection of reflected light intensity renders it sensitive to light source fluctuations and detector dark noise, and its dynamic range is relatively limited. To address these challenges, we have developed a multi-channel I-SPR sensing platform featuring rapid wavelength interval selection technology. This system optimizes the sensing wavelength according to the refractive indices of different samples, mitigating issues related to inconsistent SPR signals from various biomolecules. Our improved I-SPR technology enables high-throughput biomolecular detection with a refractive index range size of 2.035 × 10−2 for dynamic monitoring, reaching a leading role among the existing I-SPR technologies. This represents the widest linear dynamic range for I-SPR to date. Experimental results on protein binding kinetic constants KD are consistent with those obtained from commercially available instruments. We believe that this study is expected to accelerate the development of SPR technology toward broader biological applications. [ABSTRACT FROM AUTHOR]

AbstractReceptor–ligand binding, which is crucial to a variety of biomedical and biochemical processes, immune responses, and signal transduction, forms the basis for many biotechnological applications. The specific binding between a receptor and a ligand is the beginning of the biological function of the receptor or ligand molecule. Therefore, a summary study of methods for quantitative determination of receptor–ligand interaction kinetics is necessary. In this review, the kinetic parameters that traditionally describe the pattern of receptor–ligand interactions are first introduced. We then summarize and analyze methods for quantitative determination of receptor–ligand interaction kinetics, including direct kinetic measurements, cytology-based measurements, computational chemistry-based measurements, and single-molecule force spectrometry technique measurements of receptor–ligand interactions. Direct measurements of the kinetics of receptor–ligand interactions are further described in methods based on surface plasmon resonance, surface-enhanced Raman spectroscopy, photoelectrochemistry, mass spectrometry binding analyses, nuclear magnetic resonance technology, and electrochemical methods. This review provides a comprehensive and accurate description of the kinetic studies of protein receptor–ligand interactions. [ABSTRACT FROM AUTHOR]