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Optical Control of Biomimetic Nanoparticle Catalysts Based Upon the Metal Component
摘要： Nanoparticle catalysts provide an intriguing route to achieving sustainable reactivity. Recent evidence has suggested that both the underlying metallic core and the passivating ligand layer can be exploited to control reactivity. The intimate interactions between the core metal and structure of the ligand layer can change based upon the metal used to generate the catalytic particle. Through judicious selection of both components, nanoparticle catalytic systems can be designed to be stimuli responsive for controlled reactivity. Herein we demonstrate the effects of the underlying metal on the optically modulated catalytic activity of peptide-capped noble metal nanoparticles. For this, a photoswitch was incorporated into the peptide that enables reversible reconfiguration of the bioligand overlayer structure between two conformations based upon the isomerization state of the photoswitch. These changes in activity are dependent upon the inorganic metal of the particle core, and we exploit this dependence to demonstrate changes in the activity. The materials were fully characterized via spectroscopic methods and microscopy to correlate the observed reactivity to the material composition. The results provide new pathways to achieve remotely responsive catalysts that could be important for controlled multistep reactions or be exploited for other applications including biosensing and plasmonic devices.
关键词： optically modulated catalytic activity,peptide-capped noble metal nanoparticles,biosensing,Nanoparticle catalysts,photoswitch,plasmonic devices
更新于2025-09-23 15:21:21
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Fluorescent Properties of Gd-Doped Zno Nanonporous Networks & Its Application in Optical Biosensing
摘要： This research presents a study of the fluorescent properties of new materials based on gadolinium-doped zinc oxide nanoporous networks obtained by sol gel method on the surface of microcrystalline silicon. The effect of co-doping of different concentrations of Gd ions on the emission properties of ZnO nanoparticles has been investigated. Emissions of such biomolecules as protein, amino acids and porphyrin and its detection limits were studied for the purpose of practical application of Gd-doped ZnO nanonporous networks as an element of an optical biosensor technology.
关键词： sol-gel method,nanoporous networks,optical biosensing,fluorescent properties,Gd-doped ZnO
更新于2025-09-23 15:21:01
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A fibrinogen biosensing platform based on plasmonic Ga nanoparticles and aminosilanea??titanate antibody trapping
摘要： The era of personalized medicine calls for rapid detection of key biomolecules, such as serum proteins, as general indicators of a healthy/sickness state. The fabrication, biofunctionalization and calibration of a fibrinogen biosensing platform based on plasmonic gallium nanoparticles is detailed in the present work. The first step consisted in the deposition of Ga nanoparticles on Si substrates by means of Joule-effect thermal evaporation technique. A distribution of nanodroplets could be evidenced by scanning electron microscopy. The biofunctionalization of the samples was carried out using aminosilane- titanate thin hybrid layers prepared by a sol-gel route. The integration of functional amino groups could be confirmed by spectroscopic methods. Then, in order to sensitize the platform surface to fibrinogen, specific immunoglobulins have been immobilized. We monitored the plasmon wavelength changes along the fabrication cascade and during detection assays with calibrated fibrinogen solutions in phosphate buffered saline. From the ellipsometric analysis, three operational ranges as a function of fibrinogen concentration can be identified, with an out of range response for low concentration, a linear response behavior in the 1-10 μM healthy range, and a tendency to saturation at high concentration.
关键词： Biosensing,biofunctionalization,Plasmonic Ga nanoparticles,Fibrinogen
更新于2025-09-23 15:21:01
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Selective Uropathogenic E. coli Detection Using Crossed Surface-Relief Gratings
摘要： Urinary tract infections (UTIs) are one of the major burdens on public healthcare worldwide. One of the primary causes of UTIs is the invasion of the urinary tract by uropathogenic Escherichia coli (UPEC). Improper treatment of bacterial infections like UTIs with broad-spectrum antibiotics has contributed to the rise of antimicrobial resistance, necessitating the development of an inexpensive, rapid and accurate detection of UPEC. Here, we present real-time, selective and label-free detection of UPEC using crossed surface-relief gratings (CSRGs) as nanometallic sensors incorporated into an optical sensing platform. CSRGs enable real-time sensing due to their unique surface plasmon resonance (SPR)-based light energy exchange, resulting in detection of a very-narrow-bandwidth SPR signal after the elimination of residual incident light. The platform’s sensing ability is experimentally demonstrated by the detection of bulk refractive index (RI) changes, with a bulk sensitivity of 382.2 nm/RIU and a resolution in the order of 10?6 RIU. We also demonstrate, for the ?rst time, CSRG-based real-time selective capture and detection of UPEC in phosphate-buffered saline (PBS) solution, in clinically relevant concentrations, as opposed to other UTI-causing Gram-negative bacteria. The platform’s detection limit is calculated to be 105 CFU/mL (concentration on par with the clinical threshold for UTI diagnosis), with a dynamic range spanning four orders of magnitude. This work paves the way for the development of inexpensive point-of-care diagnosis devices focusing on effective treatment of UTIs, which are a burden on public healthcare due to the rise in the number of cases and their recurrences in the recent past.
关键词： crossed surface-relief gratings,nanoplasmonics,surface plasmon resonance,urinary tract infection,biosensing,uropathogenic E. coli,surface-relief gratings
更新于2025-09-23 15:21:01
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Dual responsive enzyme mimicking of ternary polyaniline-MnO2-Pd nanowires and its application in colorimetric biosensing
摘要： In recent years, a significant challenge in material science is to fabricate novel functional nanomaterials to mimic the function of natural enzymatic systems. Herein, ternary polyaniline (PANi)-MnO2-Pd nanowires (NWs) are synthesized through a two-step redox reaction process. The prepared PANi-MnO2-Pd NWs were explored to exhibit dual responsive enzyme-like efficiencies, e.g. peroxidase and oxidase-like activities. With the assistance of H2O2, the obtained ternary PANi-MnO2-Pd NWs were able to oxidize the typical peroxidase substrate of 3,3’,5,5’-tetramethylbenzidine (TMB) to yield the oxidized TMB with a blue color, exhibiting a much better peroxidase-like activity than the synthesized PANi-MnO2 NWs alone and Pd nanoparticles owing to the interfacial electron transfer effect among the components. In addition, in the absence of H2O2, the prepared PANi-MnO2-Pd NWs could also oxidize TMB to display an excellent oxidase-like activity. Based on the dual responsive enzyme-like characteristic of the obtained ternary PANi-MnO2-Pd NWs, a rapid and applicative colorimetric way to sensitively determine L-cysteine and ascorbic acid (AA) has been developed. The limits of detection based on the two systems were estimated to be as low as 118 and 34 nM, respectively. We believe that the prepared ternary PANi-MnO2-Pd NWs with both peroxidase and oxidase-like activities will show broad potential applications in bioscience and bioengineering.
关键词： palladium,colorimetric biosensing,enzyme-mimicking,manganese dioxide,polyaniline
更新于2025-09-23 15:21:01
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Highly selective and label-free Love-mode surface acoustic wave biosensor for carcinoembryonic antigen detection using a self-assembled monolayer bioreceptor
摘要： A love-mode surface acoustic wave (SAW) biosensor based on ST-cut quartz was developed for highly selective and label-free detection of carcinoembryonic antigen (CEA). The delay line area of an interdigital transducer (IDT) based SAW device was coated with gold and then chemically modified through thioglycolic acid–EDC/NHS reaction mechanism. A self-assembled monolayer of anti-CEA was further immobilized on the bioreceptors through the coupling layer. The biosensing capability of the SAW device was evaluated using solutions of CEA with various concentrations and limit of detection was obtained at 0.31 ng/ml of CEA, which is better than the results reported by the literatures available for CEA detection using SAW device. The real-time detection capability of the biosensor was evaluated using clinical serum samples and selectivity was evaluated using mixed solutions of CEA with other common tumor marking proteins. Long-term stability of the biosensor was also evaluated over a period of 30 days and the immunoassay response has shown only 8% decrease in performance within the whole period. The binding of CEA onto the bioreceptor was evaluated through Langmuir and Freundlich sorption isotherm kinetic studies as well.
关键词： SAW,Piezoelectricity,Biosensing,CEA,Label free,SAM
更新于2025-09-23 15:19:57
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Impact of metal crystallinity-related morphologies on the sensing performance of plasmonic nanohole arrays
摘要： Plasmonic nanohole arrays for biosensing applications have attracted tremendous attention because of their flexibility in optical signature design, high multiplexing capabilities, simple optical alignment setup, and high sensitivity. The quality of the metal film, including metal crystallinity and surface roughness, plays an important role in determining the sensing performance because the interaction between free electrons in the metal and incident light is strongly influenced by the metal surface morphology. We systematically investigated the influence of metal crystallinity-related morphologies on the sensing performance of plasmonic nanohole arrays after different metal deposition processes. We utilised several non-destructive nanoscale surface characterisation techniques to perform a quantitative and comparative analysis of the Au quality of the fabricated sensor. We found empirically how the surface roughness and grain sizes influence the permittivity of the Au film and thus the sensitivity of the fabricated sensor. Finally we confirmed that the deposition conditions that provide both low surface roughness and large metal grain sizes improve the sensitivity of the plasmonic sensor.
关键词： sensitivity,Plasmonic nanohole arrays,biosensing,metal crystallinity,surface roughness
更新于2025-09-23 15:19:57
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Mechanisms of Fano-resonant biosensing: Mechanical loading of plasmonic oscillators
摘要： Distinctively narrow and asymmetric line shape Fano resonances arise due to resonant interactions of sub-radiant and super-radiant modes in plasmonic nanostructures and metamaterials. A number of recent experimental studies have shown unique opportunities provided by highly dispersive Fano resonances in biosensing applications. However, there is limited understanding of Fano resonant optical response to biomolecular accumulation. Here, we introduce a phenomenological model that can precisely describe the intricate nature of the Fano resonances in plasmonic nanohole arrays and provide unambiguous physical insights into biosensing experiments. Using rigorous electromagnetic simulations and experimental measurements as benchmarking tools, we show that the non-trivial contribution of molecular accumulation to Fano resonant plasmonic response can be incorporated as a mechanical loading effect in a coupled-oscillator model. Quite remarkably, our phenomenological approach captures the complex spectral response of the Fano resonance profile and asymmetric linewidth broadening upon molecular accumulation. Furthermore, in strong agreement with our experimental measurements, we show that our parameterized model has predictive power in fine tuning the Fano resonant extraordinary light transmission lineshape using structural design parameters without resorting to electromagnetic simulations. Our phenomenological model provides a general analytical method that can be adapted to understand biomolecular detection measurements in different plasmonic and metamaterial systems.
关键词： Biosensing,Extraordinary light transmission,Plasmonics,Plasmonic nanoholes,Fano resonances,Label-free detection
更新于2025-09-23 15:19:57
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Field localization of hexagonal and short-range ordered plasmonic nanoholes investigated by cathodoluminescence
摘要： Plasmonic nanoholes have attracted significant attention among nanoplasmonic devices, especially as biosensing platforms, where nanohole arrays can efficiently enhance and confine the electromagnetic field through surface plasmon polaritons, providing a sensitive detection. In nanohole arrays, the optical resonances are typically determined by the inter-hole distance or periodicity with respect to the surface plasmon wavelength. However, for short-range ordered (SRO) arrays, the inter-hole distance varies locally, so the plasmon resonance changes. In this study, we investigate the local resonance of SRO nanoholes using a cathodoluminescence technique and compare it with hexagonally ordered nanoholes. The cathodoluminescence photon maps and resonance peak analysis reveal that the electric fields are confined at the edges of holes and that their resonances are determined by inter-hole distances as well as by their distributions. This demonstrates the Anderson localization of the electromagnetic waves showing locally enhanced electromagnetic local density of states in SRO nanoholes.
关键词： Anderson localization,biosensing,cathodoluminescence,Plasmonic nanoholes,surface plasmon polaritons
更新于2025-09-23 15:19:57
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Rapid label-free detection of intact pathogenic bacteria <i>in situ via</i> surface plasmon resonance imaging enabled by crossed surface relief gratings
摘要： The unique plasmonic energy exchange occurring within metallic crossed surface relief gratings (CSRGs) has recently motivated their use as biosensors. However, CSRG-based biosensing has been limited to spectroscopic techniques, failing to harness their potential for integration with ubiquitous portable electronics. Here, we introduce biosensing via surface plasmon resonance imaging (SPRi) enabled by CSRGs. The SPRi platform is fully integrated including optics and electronics, has bulk sensitivity of 613 Pixel Intensity Unit (PIU)/Refractive Index Unit (RIU), a resolution of 10?6 RIU and a signal-to-noise ratio of ～33 dB. Finite-Difference Time-Domain (FDTD) simulations confirm that CSRG-enabled SPRi is supported by an electric field intensity enhancement of ～30 times, due to plasmon resonance at the metal-dielectric interface. In the context of real-world biosensing applications, we demonstrate the rapid (<35 min) and label-free detection of uropathogenic E. coli (UPEC) in PBS and human urine samples for concentrations ranging from 103 to 109 CFU mL?1. The detection limit of the platform is ～100 CFU mL?1, three orders of magnitude lower than the clinical detection limit for diagnosis of urinary tract infection. This work presents a new avenue for CSRGs as SPRi-based biosensing platforms and their great potential for integration with portable electronics for applications requiring in situ detection.
关键词： crossed surface relief gratings,portable electronics,biosensing,pathogenic bacteria detection,surface plasmon resonance imaging
更新于2025-09-23 15:19:57