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We achieved an ultrahigh Q surface lattice resonance (SLR) using a conventional U-shaped split ring resonator (U-SRR) array. Numerical results confirmed by semi-analytical analysis show that with the transmission resonance amplitude up to 0.8, the Q-factor of the SLR can still surpass 104. The physical mechanisms of the ultrahigh Q-factor were also investigated. Besides the radiation suppression provided by conventional SLR, the unique geometry of the U-SRR can further offer dual radiation suppression mechanisms: reduction of the dipole moment and excitation of the in-plane quadrupole. We expect that the proposed ultrahigh Q SLR platform will be explored for more flexible and advanced nanoscale devices.
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Developing a simple, economical, sensitive, and selective method for label-free direct detection analytes is attractive, especially the strategies that could achieve signal amplification without complicated operations. Herein, a dual-fluorescence colorimetric nanoswitch sensing platform for label-free direct melamine (MEL) detection was established. We first explored the relationship between MEL-induced aggregation of gold nanoparticles (AuNPs) and size and determined the optimal size to be 37 nm. Using surfactant Triton X-100 to modify AuNPs and clarify possible interaction mechanisms to improve detection performance. The dynamic changes of surface plasmon resonance absorption peaks in the dispersed and aggregated states of AuNPs were skillfully utilized to match the emission of multicolor gold nanoclusters to trigger the multi-inner filter effect. Accompanied by the addition of MEL-induced AuNPs to change from dispersed to aggregated state, the fluorescence of green-emitting and red-emitting gradually turned on and turned off, respectively. The fluorescence turn-on mode detection limit was 10 times higher than the colorimetric method and as low as 5.5 ng/mL; the detection took only 10 min. The sensor detected MEL in spiked milk samples with a good recovery in the range of 81.2-111.0 % with a coefficient of variation less than 11.4 % and achieved a good correlation with commercial kits. The proposed sensor integrates numerous merits of label-free, multi-signal readout, self-calibration, simple operations, and economical, which provides a promising tool for convenient on-site detection of MEL.
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Colorimetría , Oro , Nanopartículas del Metal , Leche , Triazinas , Triazinas/análisis , Triazinas/química , Oro/química , Nanopartículas del Metal/química , Colorimetría/métodos , Leche/química , Animales , Límite de Detección , Fluorescencia , Contaminación de Alimentos/análisis , Espectrometría de Fluorescencia/métodosRESUMEN
The abuse of olaquindox (OLA) as both an antimicrobial agent and a growth promoter poses significant threats to the environment and human health. While nanoreactors have proven effective in hazard detection, their widespread adoption has been hindered by tedious chemical processes and limited functionality. In this study, we introduce a novel green self-assembly strategy utilizing invertase, horseradish peroxidase, antibodies, and gold nanoclusters to form an aggregation-induced emission-type zeolitic imidazolate framework-8 nanoreactor. The results demonstrate that the lateral flow immunoassay not only allows for qualitative naked eye detection but also enables optical analysis through the fluorescence generated by aggregated gold nanoclusters and enzyme-catalyzed enhancement of visible colorimetric signals. To accommodate more detection scenarios, the photothermal effects and redox reactions of the nanoreactor can fulfill the requirements of thermal sensing and electrochemical analysis for smartphone applications. Remarkably, the proposed approach achieves a detection limit 17 times lower than conventional methods. Besides, the maximum linear range spans from 0.25 to 5 µg/L with high specificity, and the recovery is 85.2-112.9% in environmental water and swine urine. The application of this high-performance nanoreactor opens up avenues for the construction of multifunctional biosensors with great potential in monitoring hazardous materials.
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Quinoxalinas , Teléfono Inteligente , Zeolitas , Animales , Biónica , Oro , Nanotecnología , PorcinosRESUMEN
BACKGROUND: The utilization of inner filter effect (IFE) brings more opportunities for construction of fluorescence immunoassays but remains a great challenge, especially how to select best donor in the face of extensive fluorescent nanomaterials. Aflatoxin B1 possesses high toxicity among mycotoxins and is frequently found in agricultural products that may significantly threaten to human health. Therefore, with the help of signal transduction mechanism of IFE to develop a convenient and sensitive approach for AFB1 detection is of great significance in ensuring food safety. RESULTS: Herein, the classical alkaline phosphatase (ALP) catalyzes hydrolysis of p-nitrophenylphosphate to produce p-nitrophenol (PNP) was employed as a model reaction, which intends to explore tunable multicolor fluorescence of gold nanoclusters (AuNCs) for matching PNP to maximize IFE efficiency. The luminescent green-emitting AuNCs were selected as an optimal donor in terms of excellent spectral overlap, high photoluminescence, and adequate system adaptability, thus achieving a 22-fold increase in sensitivity improvement compared to colorimetric method for ALP detection. The fluorescence quenching mechanism between PNP and AuNCs was validated as IFE by studying ultraviolet absorption, zeta potentials and fluorescence lifetime. In light of this, we integrated a highly specific antibody-antigen recognition system, efficient enzymatic reaction and excellent optical characteristics of AuNCs to develop dual-mode immunoassay for AFB1 monitoring. The sensitivity of fluorometric immunoassay was lower to 0.06 ng/mL, which obtained a 3.5-fold improvement compared to "gold standard" ELISA. Their practicability and applicability were confirmed in the tap water, corn, wheat and peanuts samples. SIGNIFICANCE: This work provides an easy-to-understand screening procedure to select optimal donor-acceptor pairs in IFE analysis. Furthermore, we expect that integration of IFE-based signal conversion strategy into mature immunoassay not only extends the signal types, simplifies signal amplification steps, and reduces the false-positive/false-negative rates, but also provides a simple, convenient, and versatile strategy for monitoring of trace other contaminants.
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Fosfatasa Alcalina , Nanopartículas del Metal , Humanos , Límite de Detección , Fosfatasa Alcalina/análisis , Hidrólisis , Espectrometría de Fluorescencia/métodos , Fluorometría , ColorantesRESUMEN
De novo peptide sequencing is a promising approach for novel peptide discovery, highlighting the performance improvements for the state-of-the-art models. The quality of mass spectra often varies due to unexpected missing of certain ions, presenting a significant challenge in de novo peptide sequencing. Here, we use a novel concept of complementary spectra to enhance ion information of the experimental spectrum and demonstrate it through conceptual and practical analyses. Afterward, we design suitable encoders to encode the experimental spectrum and the corresponding complementary spectrum and propose a de novo sequencing model $\pi$-HelixNovo based on the Transformer architecture. We first demonstrated that $\pi$-HelixNovo outperforms other state-of-the-art models using a series of comparative experiments. Then, we utilized $\pi$-HelixNovo to de novo gut metaproteome peptides for the first time. The results show $\pi$-HelixNovo increases the identification coverage and accuracy of gut metaproteome and enhances the taxonomic resolution of gut metaproteome. We finally trained a powerful $\pi$-HelixNovo utilizing a larger training dataset, and as expected, $\pi$-HelixNovo achieves unprecedented performance, even for peptide-spectrum matches with never-before-seen peptide sequences. We also use the powerful $\pi$-HelixNovo to identify antibody peptides and multi-enzyme cleavage peptides, and $\pi$-HelixNovo is highly robust in these applications. Our results demonstrate the effectivity of the complementary spectrum and take a significant step forward in de novo peptide sequencing.
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Análisis de Secuencia de Proteína , Espectrometría de Masas en Tándem , Espectrometría de Masas en Tándem/métodos , Análisis de Secuencia de Proteína/métodos , Péptidos , Secuencia de Aminoácidos , Anticuerpos , AlgoritmosRESUMEN
A novel way to measure humidity through testing the emissivity of an area radiant source is presented in this paper. The method can be applied in the environment at near room temperature (5~95 °C) across the relative humidity (RH) range of 20~90% RH. The source, with a grooved radiant surface, works in the far infrared wavelength band of 8~12 µm. The Monte-Carlo model for thermal radiation was set up to analyze the V-grooved radiant surface. Heat pipe technology is used to maintain an isothermal radiant surface. The fuzzy-PID control method was adopted to solve the problems of intense heat inertia and being easily interfered by the environment. This enabled the system to be used robustly across a large temperature range with high precision. The experimental results tested with a scanning radiant thermometer showed that the radiant source can provide a uniform thermal radiation capable of satisfying the requirements of humidity testing. The calibration method for the radiant source for humidity was explored, which is available for testing humidity.