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An automatic multi-thread image segmentation embedded system for surface plasmon resonance sensor
摘要： In order to reduce the uncertainties associated with manual selection of regions of interest (ROIs) commonly used in Surface Plasmon Resonance (SPR) imaging system, we proposed and implemented an automatic image segmentation method in an embedded system to facilitate the potential real-time applications. Intuitive marker-controlled watershed algorithm is developed to segment ROIs (reaction, blank, and background regions) from images acquired from an experimental image SPR system. The marker assignment algorithms and pre-processing algorithms are executed in parallel by multi-threading programming on the multi-core embedded system to both real-time and good quality of segmentation. This method exhibited a good robustness in a series of ROIs segmentation test. Furthermore, the intensity response from triplicate detection of glucose standard solutions indicated a good reproducibility of data. The linear range was from 2.5 mg/mL to 20.4 mg/mL, with a correlation coefficient (R2) of 0.999 and sensitivity of 2.69 a.u./mg/mL. In conclusion, the proposed automatic image segmentation method effectively makes the measurement more precise and simplified.
关键词： Optical sensor,Surface plasmon resonance (SPR),Biosensor,Watershed algorithm,Image segmentation
更新于2025-09-23 15:23:52
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Reusable surface plasmon resonance sensor for rapid detection of Cu2+ based on modified-chitosan thin film as an active layer
摘要： In this article, a reusable surface plasmon resonance (SPR) sensor for rapid detection of copper ions (Cu2+), based on optimized silver/gold (Ag/Au) composite film modified by modified-chitosan (MCS) thin film as an active layer, was achieved. We employed a four-layer Kretchmann semi-cylindrical prism configuration and induced a reference beam into the experimental system to improve the sensitivity and stability, and investigated the cross-linking technique of CS solution, the spin coating process of MCS film, the stability of active layer, the rebirth power of SPR sensor, and the detection for trace Cu2+. The rate of swelling or dissolution of MCS film after flushing sensor chip for four times is less than 9×10?4/min, and the decline of signal value is less than 1.5% after MCS film adsorbing Cu2+ and multiple flushing. The elution and capacity rates are above 96% after five times of elution for the sensor by EDTA solution with 0.5mmol/L. Within 1-5ppm, the SPR sensor was found to possess sensitivity of 0.7271ppm?1. The LOD is 18ppb for the trace Cu2+. The present SPR sensor not only could be used in trace monitoring of Cu2+ but also could be extended to other potential applications.
关键词： Copper ions,Reutilization,Composite film,Modified-chitosan,Surface plasmon resonance
更新于2025-09-23 15:23:52
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Ultrasensitive U-shaped fiber optic LSPR cytosensing for label-free and in situ evaluation of cell surface N-glycan expression
摘要： Label-free and in situ detection of N-glycan expression on surface of cells is vital for understanding the progression of cancer. Herein, cytosensing based on U-shaped fiber optic local surface plasmon resonance (LSPR) was developed for cancer cell detection and N-glycan evaluation on cell surface. The U-shaped fiber optic LSPR has high refractive index sensitivity (RIS). Therefore, U-shaped fiber optic LSPR cytosensing afforded ultrasensitivity for cancer cell detection with the limit of detection (LOD) of 30 cells/mL and good linearity in a wide range of 1×102-1×106 cells/mL under the optimal conditions of modified AuNPs size and Con A concentration. The U-shaped fiber optic LSPR cytosensing shows more than 29 times lower limit of detection than the straight ones. More importantly, the prepared U-shaped cytosensing was applied to evaluate the N-glycan expression level on the surface of cancer cells under different concentration external stimuli of inhibitor tunicamycin (TM). Noticeably, U-shaped fiber optic LSPR cytosensing showed an acceptable reproducibility, satisfactory anti-interference and good selectivity, and was also applied in the assessment of N-glycan expression on surface of six kinds of cell lines. Therefore, the U-shaped fiber optic LSPR offers a feasible tool in biophysical research and clinical diagnosis for cancer.
关键词： Cancer cell,N-Glycan expression,Cytosensing,U-shaped fiber optic probe,Local surface plasmon resonance
更新于2025-09-23 15:23:52
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Blu-ray DVD as SERS substrate for reliable detection of albumin, creatinine and urea in urine
摘要： We report here the working of a simple reproducible surface enhanced Raman scattering (SERS) substrate by efficiently guiding localized plasmon resonance (LSPR) field of gold nanoparticles (AuNPs) through trapping it in the nano channels of a blu-ray digital versatile disc (BRDVD). SERS based sensing of the designed substrate has been performed. The trapped AuNPs in the channel of the BRDVD generate guided mode resonance (GMR) field and the photon lifetime of the coupled em field in the channel increases which accounts for overall enhancement of the local field intensity. These two factors are primarily responsible for enhancement of the scattered Raman signal from the substrate. The proposed SERS substrate yields reasonably stable signal intensity over a period of 45 days. With the designed substrate Raman signal intensities of three clinically important chemicals namely albumin, creatinine and urea in urine have been measured and quantified reliably. The minimum concentration of albumin, creatinine and urea which can be measured by Raman spectrometer are 0.1 μg/mL, 0.2 μg/mL and 0.6 μg/mL respectively. These values are well below the normal range and thus meet the requirement of detection and analysis of these chemicals for different clinical purposes.
关键词： SERS,Nanochannel,LSPR,BRDVD,Guided mode resonance,Urine sample
更新于2025-09-23 15:23:52
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Quantification of Glucose via in situ Growth of Cu2O/Ag Nanoparticles
摘要： The monitoring of glucose levels in blood is extremely important for the effective control of diabetes. Nanomaterial-based approaches for the quantification of glucose typically require two steps: material preparation and the actual glucose measurement. Herein, we report a single-step method that combines these functions via the in situ growth of Cu2O/Ag nanoparticles (NPs). Mechanistically, we use glucose itself to reduce Cu2+ and Ag+ ions that are stabilized with 3-mercaptopropionic acid (3-MPA) and bovine serum albumin (BSA) under alkaline conditions to form Cu2O/Ag NPs and produce a color change in solution due to plasmonic resonance at 400 nm, which can be related back to the concentration of glucose. We study several factors in this reaction, including the molar ratios of the metal ions and 3-MPA, the reaction time, and the temperature to control the synthesis of the Cu2O/Ag NPs and thus their sensitivity toward glucose. Introducing BSA into the system is a key factor for the quantification of glucose in blood without pretreatment, improving the probe’s limit of detection and reducing the sample volumes to 1 μL. This colorimetric assay based on Cu2O/Ag NPs exhibits excellent sensitivity and specificity toward glucose, and a linear relationship with glucose concentrations ranging from 15 to 300 μM and a limit of detection of 9.2 μM. As proof of concept, we demonstrated that the Cu2O/Ag NP probes could successfully detect glucose in two representative blood samples by neglecting interferences from various common species, demonstrating the potential of this technique in point-of-care analysis.
关键词： plasmonic resonance,3-mercaptopropionic acid,bovine serum albumin,silver nanoparticles,glucose quantification,Cu2O
更新于2025-09-23 15:23:52
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Nuclear spin dynamics in [001] AlAs quantum well in the regime of integer and fractional quantum Hall effect
摘要： Relaxation of nuclear spins located in the vicinity of 2D electron system confined in a 16 nm [001] AlAs/AlGaAs quantum well was studied with the aid of electron spin resonance (ESR) in the regime of integer and fractional quantum Hall effect. Nuclear spin-lattice relaxation time τ was measured from the time decay of the Overhauser shift near different filling factors of the electron system. The resultant dependence of τ on filling factor turned out to be nontrivial. At the temperature 1.5 K τ reached its maximal value at the exact filling ν = 1 and decreased when ν was altered, yet this maximum vanished when the system was cooled down to 0.5 K. The fractional quantum Hall effect state at the filling of 2/3 was formed at the temperature of 0.5 K, and the development of this state was accompanied by the slowing of the nuclear spin relaxation. This observation suggests the enhancement of energy gap in the spin excitation spectrum of two-dimensional electrons at 2/3 state.
关键词： quantum wells,quantum Hall effect,spin dynamics,electron paramagnetic resonance
更新于2025-09-23 15:23:52
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An fluorescent aptasensor for sensitive detection of tumor marker based on the FRET of a sandwich structured QDs-AFP-AuNPs
摘要： The detection of alpha-fetoprotein (AFP) is of great importance for hepatocellular carcinoma (HCC) diagnosis, but it needs to be further improved because of poor sensitivity and complicated operating steps. In this paper, a simple and sensitive homogeneous aptasensor for AFP has been developed based on F?rster resonance energy transfer (FRET) where the AFP aptamer labeled luminescent CdTe quantum dots (QDs) as a donor and anti-AFP antibody functional gold nanoparticles (AuNPs) as an acceptor. In the presence of AFP, the bio-affinity between aptamer, target, and antibody made the QDs and AuNPs close enough, thus the fluorescence of CdTe QDs quenched though the FRET between QD and AuNP. The fluorescent aptasensor for AFP showed a concentration-dependent decrease of fluorescence intensity in the low nanomolar range and a detecting linear range of 0.5-45 ng mL?1, with a detection limit of 400 pg mL?1. Moreover, this homogeneous aptasensor is simple and reliable, and obtained satisfying results for the detection of AFP in human serum samples. With more and more aptamers for biomarkers have been selected gradually, this approach could be easily extended to detection of a wide range of biomarkers. The proposed aptasensor has great potential for carcinoma screening in point-of-care testing and even in field use.
关键词： alpha fetoprotein (AFP),fluorescent aptasensor,biomarker,hepatocellular carcinoma,F?rster resonance energy transfer (FRET)
更新于2025-09-23 15:23:52
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The Effect of Physical and Geometric Parameters on the Surface Plasmon Resonance Response of a Fiber Optic Biosensor: Sensitivity Analysis and Numerical Optimization
摘要： The study of the influence of optical and geometric parameters on the spectral response of the biosensor is an important step towards the optimization of these parameters. In this study, an improved SPR biosensor with a high resolution is proposed. The present SPR biosensor is based on an optical fiber that takes the place of the prism, compared with the conventional configuration, in order to simplify the detection process, overcome the stresses caused by the massive prism and obtain a reliable and efficient miniature device. The modeling procedure is based on a matrix formalism developed for the optical studies of multilayer media. We have discussed the effect of physical and optical parameters on the resonance curves, from the theoretical analysis of the transmitted power. The obtained results show that the response of the biosensor is highly dependent on these parameters. The optimum values of the length of the sensitive area, the core diameter of the optical fiber, the thickness of the metal layer and the refractive index of external environment have been determined.
关键词： Optical Fiber,Biosensors,Numerical Optimization,Surface Plasmon Resonance SPR,Sensitivity
更新于2025-09-23 15:23:52
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Design of titanium nitride coated PCF-SPR sensor for liquid sensing applications
摘要： In this paper, a titanium nitride (TiN) coated highly sensitive PCF-SPR sensor design is proposed and numerically analyzed. Titanium shows the excellent plasmonic properties in the visible and infrared regions and it has low loss and corrosion resistive nature. In this theoretical analysis, we introduce the dependencies of the confinement loss, wavelength sensitivity and amplitude sensitivity to the operating wavelength, thickness of TiN, channel width and refractive index of the measured liquid. For the proposed PCF-SPR sensor design, the high wavelength sensitivity and the refractive index resolution of ～10,000 nm/RIU and ～2.0 × 10?5 has been achieved in the refractive index (RI) range of 1.385–1.40, respectively. Even the proposed design has low amplitude sensitivity, but this proposed sensor will be used in detection of RI of chemicals, biochemical analyte with low concentrations, and highly demand in lab-on-a-chip PCF-SPR sensing probe devices.
关键词： Sensitivity,PCF,Surface plasmon resonance
更新于2025-09-23 15:23:52
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Bumpy Hollow Gold Nanospheres for Theranostic Application: Effect of Surface Morphology on Photothermal Conversion Efficiency
摘要： The combination of hollow core and rugose surface morphology is highly attractive for photoactive near-infrared (NIR) nanomaterials. Here, we present a facile pH modification to hollow gold nanosphere (HGN) synthesis to enable controlled tuning of the surface morphology from smooth to very bumpy. Unlike other methods, the synthetic protocol does not require harsh surfactants, secondary reducing agents, or organic solvents. The resultant bumpy HGNs (bHGNs) are highly monodisperse with little variation in protrusion length from particle to particle. Mechanistic studies suggest that surface rugosity is mainly controlled by the presence of free OH- ions in solution. We also present the first systematic investigation into the effect of surface morphology on the photothermal conversion efficiency (PCE) of bumpy as well as smooth HGNs, with a maximum PCE reaching 99%. Although expected to have a higher scattering component, the bHGNs retain the excellent PCE of their smooth counterparts, which may be due to efficient reabsorption of scattered light.
关键词： surface plasmon resonance,photothermal conversion efficiency,heat generation,surface morphology,hollow gold nanospheres
更新于2025-09-23 15:23:52