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Graphene quantum dots enhanced ToF-SIMS for single-cell imaging
摘要： Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has shown promising applications in single-cell analysis owing to its high spatial resolution molecular imaging capability. One of the main drawbacks hindering progress in this field is the relatively low ionization efficiency for biological systems. The complex chemical micro-environment in single cells typically causes severe matrix effects, leading to significant signal suppression of biomolecules. In this work, we investigated the signal enhancement effect of graphene quantum dots (GE QDs) in ToF-SIMS analysis. A × 160 magnification of ToF-SIMS signal for amiodarone casted on glass slide was observed by adding amino-functionalized GE QDs (amino-GE QDs), which was significantly higher than adding previously reported signal enhancement materials and hydroxyl group-functionalized GE QDs (hydroxyl-GE QDs). A possible mechanism for GE QD-induced signal enhancement was proposed. Further, effects of amino-GE QDs and hydroxyl-GE QDs on amiodarone-treated breast cancer cells were compared. A significant signal improvement for lipids and amiodarone was achieved using both types of GE QDs, especially for amino-GE QDs. In addition, ToF-SIMS chemical mapping of single cells with better quality was obtained after signal enhancement. Our strategy for effective ToF-SIMS signal enhancement holds great potential for further investigation of drug metabolism pathways and the interactions between the cell and micro-environment.
关键词： Signal enhancement,Single-cell analysis,Graphene quantum dots,Time-of-flight secondary ion mass spectrometry
更新于2025-11-14 15:32:45
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Dynamic Nuclear Polarization of Metal–Organic Frameworks Using Photoexcited Triplet Electrons
摘要： While dynamic nuclear polarization based on photoexcited triplet electrons (triplet-DNP) has the potential to hyperpolarize nuclear spins of target substrates in the low magnetic field at room temperature, there has been no triplet-DNP system offering structural rigidity and substrate accessibility. Here, we report the first example of triplet-DNP of nanoporous metal?organic frameworks. Accommodation of a carboxylate-modified pentacene derivative in a partially deuterated ZIF-8 (D-ZIF-8) results in a clear 1H NMR signal enhancement over thermal equilibrium.
关键词： dynamic nuclear polarization,photoexcited triplet electrons,metal?organic frameworks,NMR signal enhancement
更新于2025-09-23 15:21:21
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Spectral Characterization of Collinear Double-Pulse Laser Induced Breakdown Spectroscopy (DP-LIBS) for the Analysis of the Chinese Traditional Medicine <i>Artemisia annua</i>
摘要： A collinear dual-pulse laser induced breakdown spectroscopy (DP-LIBS) method was employed to analyze Chinese traditional medicine Artemisia annua. The spectral intensities and signal-to-background ratios of magnesium (II) 279.54 nm, CN 388.29 nm, calcium (II) 393.37 nm, and iron (II) 404.27 nm were used to evaluate the optical emission characteristics of A. annua induced by DP-LIBS. The temporal evolution characteristics, inter-pulse time, and laser energy values were optimized. In particular, the electron density and the temperatures of the plasma were reported as functions of the delay time. The results showed that the DP-LIBS had stronger intensity and better accuracy compared to single-pulse (SP) LIBS. The enhancement factors obtained using DP-LIBS for Mg, CN, Ca, and Fe were 7.2, 8.9, 13.8, and 3.4, respectively. This study provides important information about A. annua.
关键词： signal enhancement,plasma parameters,double-pulse laser induced breakdown spectroscopy (DP-LIBS),Artemisia annua
更新于2025-09-23 15:21:01
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Immunochromatographic System for Serodiagnostics of Cattle Brucellosis Using Gold Nanoparticles and Signal Amplification with Quantum Dots
摘要： In this article, we describe an immunochromatographic test system developed for rapid serodiagnostics of cattle brucellosis using two markers: Gold nanoparticles (GNPs) and quantum dots (QDs). The test system was compared with immunochromatographic serodiagnostics systems that use only one marker. The approbation of the test system was conducted on samples of cattle sera with low, but diagnostically significant titers of specific antibodies. We show that when two conjugates are used, the intensity of the detectable signal increases by 2–3 times compared with the test system using the QD conjugate and by more than nine times compared with the system using the GNP conjugate.
关键词： signal enhancement,cow diseases,rapid tests,lateral flow tests,functionalized nanoparticles,veterinary diagnostics
更新于2025-09-23 15:19:57
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Amplified Fluorescence by ZnO Nanoparticles vs. Quantum Dots for Bovine Mastitis Acute Phase Response Evaluation in Milk
摘要： Bovine mastitis (BM) is a prominent inflammatory disease affecting the dairy industry worldwide, originated by pathogenic agent invasion onto the mammary gland. The early detection of new BM cases is of high importance for infection control within the herd. During inflammation, various biomarkers are released into the blood circulation, which are consequently found in milk. Herein, the lysosomal activity of N-acetyl-β-D-glucosaminidase (NAGase), a predominant BM indicator, was utilized for highly sensitive clinical state differentiation. The latter is achieved by the precise addition of tetraethyl orthosilicate-coated zinc oxide nanostructures (quantum dots or nanoparticles, individually) onto a conventional assay. Enhanced fluorescence due to the nanomaterial accumulative near-field effect is achieved within real milk samples, contaminated with Streptococcus dysgalactiae, favoring quantum dots over nanoparticles (> 7-fold and 3-fold, respectively), thus revealing significant differentiation between various somatic cell counts. The main advantage of the presented sensing concept, besides its clinically relevant concentrations, is the early bio-diagnostic detection of mastitis (subclinical BM) by using a simple and cost-effective experimental setup. Moreover, the assay can be adapted for BM recovery prognosis evaluation, and thus impact on udder health status, producing an alternative means for conventional diagnosis practices.
关键词： zinc oxide,quantum dots,signal enhancement,mastitis biomarker,nanoparticles,N-acetyl-β-D-glucosaminidase
更新于2025-09-23 15:19:57
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Current trends in laser-induced breakdown spectroscopy: a tutorial review
摘要： The purpose of this tutorial article is to provide a brief update on the advances available for laser-induced breakdown spectroscopy (LIBS), focusing broad experimental and instrumental possibilities. Due to the inherent versatility of LIBS, this technique can be elegantly applied to various applications. However, during the method development one should have prior knowledge about its analytical limitations in order to obtain reliable results. In the present review, we summarize key analytical variables required for proper sample treatment, analytical signal enhancement, data processing, qualitative and quantitative approaches as well as recent research and developments using LIBS. Remarkable analytical advances have recently been proposed for LIBS and raised its analytical performance to a level never reached before. Most prominent perhaps, have been the development of many nontraditional calibration approaches based on transition atomic energies (emission wavelengths), the use of a single standard for calibration, increase of the ablated sample mass (accumulated laser pulses), and even overcoming severe LIBS problems such as the matrix effects.
关键词： LIBS,signal enhancement,calibration,qualitative analysis,data processing,sample preparation
更新于2025-09-23 15:19:57
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Investigating double pulse nanoparticle enhanced laser induced breakdown spectroscopy
摘要： Several strategies have been e?ectively tested in the past to improve the Laser Induced Breakdown Spectroscopy (LIBS) signal, involving peculiar experimental con?gurations, such as Double Pulse LIBS (DP-LIBS). Recently, sample treatment has proven to be a viable and simple way to enhance the LIBS performances; in particular, the Nanoparticle-Enhanced LIBS (NELIBS) methodology uses a deposition of metal nanoparticles (NPs) on the sample to greatly increase the emission of the LIBS plasma. In this work, we investigate the possibility of combining, for the ?rst time, DP-LIBS with NELIBS. The chosen set-up uses two parallel non-collinear laser pulses to ensure the activation of NPs during both pulses, while maintaining the low-pressure environment typical of DP-LIBS. The two laser beams are spatially separated so that the second beam is focused within the shock wave generated by the ?rst one. This con?guration allows the exploitation of the combined enhancement of both DP-LIBS and NELIBS. Several tests on copper targets have been performed to determine the best set-up for the maximum magnitude of the signal enhancement by adjusting di?erent parameters such as pulse energies and o?set distances. Commercially available silver NPs and NPs prepared by pulsed laser ablation in liquid have been tested and their performances compared with standard DP-LIBS.
关键词： Pulsed laser ablation in liquids,Double pulse LIBS,Nanoparticle enhanced LIBS,Spatially o?set DP-NELIBS,Signal enhancement
更新于2025-09-19 17:13:59
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Self-Mixing Interferometric Signal Enhancement Using Generative Adversarial Network for Laser Metric Sensing Applications
摘要： Measurement performance of self-mixing interferometric (SMI) laser sensor can be significantly affected due to the presence of noise. In this case, conventional signal enhancement techniques yield compromised performance due to several limitations which include processing signals in frequency domains only, relying mainly on first order statistics, loss of important information present in higher frequency band and handling limited number of noise types. To address these issues, we propose a solution based on using generative adversarial network, a popular deep learning scheme, to enhance SMI signal corrupted with different noise types. Thus, taking advantage of the deep networks that can learn arbitrary noise distribution from large example set, our proposed method trains the deep network model end-to-end, able to process raw waveforms directly, learn 51 different noise conditions including white noise and amplitude modulation noise for 1,140 different types of SMI waveforms made up of 285 different optical feedback coupling factor (C) values and 4 different line-width enhancement factor α values. The results show that the proposed method is able to significantly improve the SNR of noisy SM signals on average of 19.49, 16.29, 10.34 dB for weak-, moderate-, and strong-optical feedback regime signals, respectively. For amplitude modulated SMI signals, the proposed method has corrected the amplitude modulation with maximum error (using area-under-the-curve based quantitative analysis) of 0.73% for SMI signals belonging to all optical feedback regimes. Thus, our proposed method can effectively reduce the noise without distorting the original signal. We believe that such a unified and precise method leads to enhancement of performance of SMI laser sensors operating under real-world, noisy conditions.
关键词： signal noise removal,neural network for signal enhancement,Interferometry laser sensors,vibration measuring laser sensors,waveform enhancement,self-mixing signal enhancement,generative adversarial network (GAN)
更新于2025-09-16 10:30:52
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Sandwiching analytes with structurally diverse plasmonic nanoparticles on paper substrates for surface enhanced Raman spectroscopy
摘要： This report describes the systematic combination of structurally diverse plasmonic metal nanoparticles (AgNPs, AuNPs, Ag core–Au shell NPs, and anisotropic AuNPs) on flexible paper-based materials to induce signal-enhancing environments for surface enhanced Raman spectroscopy (SERS) applications. The anisotropic AuNP-modified paper exhibits the highest SERS response due to the surface area and the nature of the broad surface plasmon resonance (SPR) neighboring the Raman excitation wavelength. The subsequent addition of a second layer with these four NPs (e.g., sandwich arrangement) leads to the notable increase of the SERS signals by inducing a high probability of electromagnetic field environments associated with the interparticle SPR coupling and hot spots. After examining sixteen total combinations, the highest SERS response is obtained from the second layer with AgNPs on the anisotropic AuNP paper substrate, which allows for a higher calibration sensitivity and wider dynamic range than those of typical AuNP–AuNP arrangement. The variation of the SERS signals is also found to be below 20% based on multiple measurements (both intra-sample and inter-sample). Furthermore, the degree of SERS signal reductions for the sandwiched analytes is notably slow, indicating their increased long-term stability. The optimized combination is then employed in the detection of let-7f microRNA to demonstrate their practicability as SERS substrates. Precisely introducing interparticle coupling and hot spots with readily available plasmonic NPs still allows for the design of inexpensive and practical signal enhancing substrates that are capable of increasing the calibration sensitivity, extending the dynamic range, and lowering the detection limit of various organic and biological molecules.
关键词： SERS,surface enhanced Raman spectroscopy,interparticle coupling,microRNA detection,plasmonic nanoparticles,paper substrates,signal enhancement,hot spots
更新于2025-09-16 10:30:52
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A stage-scanning two-photon microscope equipped with a temporal and a spatial pulse shaper: Enhance fluorescence signal by phase shaping
摘要： Here, we present a stage-scanning two-photon microscope (2PM) equipped with a temporal pulse shaper and a spatial light modulator enabling full control over spectral and spatial phases of the exciting laser pulse. We demonstrate the capability of correcting wavefronts and temporal pulse distortions without cross-dependencies induced by optical elements at the same time enhancing the fluorescence signal. We implemented phase resolved interferometric spectral modulation for temporal pulse shaping and the iterative feedback adaptive compensation technique for spatial pulse modulation as iterative techniques. Sample distortions were simulated by cover glass plates in the optical path and by chirping the exciting laser pulses. Optimization of the spectral and spatial phases results in a signal increase of 30% and nearly complete recovery of the losses. Applying a measured spatial compensation phase within a real leaf sample shows the enhancement in contrast due to wavefront shaping with local fluorescence increase up to 75%. The setup allows full independent control over spatial and spectral phases keeping or improving the spatial resolution of our microscope and provides the optimal tool for sensitive non-linear and coherent control microscopy.
关键词： two-photon microscopy,wavefront shaping,spatial light modulator,fluorescence signal enhancement,temporal pulse shaping
更新于2025-09-04 15:30:14