A Simple and Sensitive Resonance Scattering Spectral Assay for Detection of Melamine Using Aptamer-Modified Nanosilver Probe

Nanosilver of 10-nm size was prepared by the NaBH₄–sodium citrate procedure, and it was modified by a single-strand DNA (ssDNA) aptamer to fabricate an AgssDNA probe for melamine. The probe was stabile at pH 7.0 Na₂HPO₄–NaH₂PO₄ buffer solutions and in the presence of 25.0 mmol/L NaCl. Upon the addition of melamine, it interacted with the probe to aggregate big clusters, which led to the resonance scattering (RS) intensity at 470 nm increasing greatly. Under the selected conditions, the increased RS intensity (ΔI _470 nm) is linear to melamine concentration in the range of 6.31–378.4 μg/L, with a regression equation of DI_{470 nm} = 1.124c + 10.8 \Delta {I_{{47}0{\rm{ nm}}}} = {1}.{124}c + { 10}.{8} and a detection limit of 3.1 μg/L. The aptamer-modified nanosilver RS assay has been applied for the determination of melamine in milk, with satisfactory results.     

Highly Sensitive Polarimetric Sensor Based on Fano Resonance for DNA Hybridization Detection

Plasmonics - Surface plasmon resonance (SPR) sensor based on reflectivity measurement has been widely studied for its convenient detection, high sensitivity, and real-time functions. However, the...     

A Highly Sensitive Enzyme Catalytic Method for the Detection of Ethanol Based on Resonance Scattering Effect of Gold Particles

In pH 8.4 Tris–HCl buffer solutions, alcohol dehydrogenase catalyzed the reaction between ethanol and nicotinamide adenine dinucleotide to produce acetaldehyde. In the medium of HCl, acetaldehyde reduced HAuCl₄ to form gold particles that exhibited a strong resonance scattering (RS) peak at 600 nm. The RS peak increased with ethanol concentration. The increased RS intensity at 600 nm (ΔI _600 nm) was proportional to the ethanol concentration (C) from 0.068 to 10.2 mmol/L, with a regression equation of ΔI _600 nm?=?35.59?C?+?16.1, and a detection limit (3σ) of 3.2 μmol/L. This proposed method was applied to detect ethanol in saliva and plant cell culture medium samples, with satisfactory results.     

Resonance Scattering Spectral Detection of Trace Pb<Superscript>2+</Superscript> Using Aptamer-Modified AuPd Nanoalloy as Probe

The resonance scattering spectral probe for Pb²⁺ was obtained using aptamer-modified AuPd Nanoalloy. In the pH 7.0 Na₂HPO₄–NaH₂PO₄ buffer solution, the aptamer interacted with AuPd nanoalloy particles to form stable aptamer-AuPd nanoalloy probe for Pb²⁺ that is stable in high concentration of salt. The probe combined with Pb²⁺ ions to form a G-quadruplex and to release AuPd nanoalloy particles that aggregate to form big particles which led the resonance scattering (RS) intensity enhancing. The reaction solution was filtered by 0.15 μm membrane to obtain the filtration containing aptamer-AuPd nanoalloy probe that has strong catalytic effect on the electrodeless nickel particle plating reaction between Ni(II) and PO₂³⁻ that exhibited a strong RS peak at 508 nm. The RS intensity at 508 nm decreased when the Pb²⁺ concentration increased. The decreased intensity (ΔI _508nm) is linear to the concentration of 0.08–42 nM Pb²⁺, with regress equation of DI_508nm = 16.3 c + 1.5 \Delta {I_{{5}0{\rm{8nm}}}} = {16}.{3}\,c + {1}.{5} , correlation coefficient of 0.9965, and detection limit of 0.04 nM Pb²⁺. The RS assay was applied to the analysis of Pb²⁺ in wastewater, with satisfactory results.     

金纳米探针瑞利共振散射法测定溶菌酶

利用共振散射技术研究了金纳米微粒与溶菌酶的相互作用.金纳米微粒可以通过静电引力及疏水作用与溶菌酶结合,使金纳米微粒粒径变大,从而导致纳米金瑞利共振散射光谱显著增强,并且在一定范围内光散射强度的增加量与溶菌酶浓度成正比.考查了作用时间、溶液酸度、共存离子及有机溶剂等条件的影响.将纳米金作为测定溶菌酶的探针,在最佳反应条件下,对溶菌酶的检出限为0.08 μg/mL.将此方法用于蛋清中溶菌酶的测定,检测结果与文献报道方法一致,结果令人满意.     

Detection of Vascular Endothelial Growth Factor Based on Gold Nanoparticles and Immunoreaction Using Resonance Light Scattering

In the study, a new assay of vascular endothelial growth factor (VEGF) has been developed by the use of gold nanoparticles (GNPs)–anti-VEGF conjugates. The immunoreaction between GNPs–anti-VEGF conjugates and VEGF took place in pH?7.5 PBS buffer solution after the addition of VEGF. The formation of GNPs modified VEGF immunocomplex resulted in the enhanced resonance light scattering (RLS) intensity at 388.0 nm. Under the optimal conditions, the magnitude of enhanced RLS intensity (ΔI _RLS) was proportional to the VEGF concentration in the range from 100 to 1,500 pg?mL^?1, with a detection limit of 60 pg?mL^?1. The surface plasma resonance absorption spectrum, the characteristics of RLS, the VEGF immunocomplex, and the optimum conditions of the immunoreaction have all been investigated. The VEGF concentrations of 20 serum specimens detected by the developed assay showed consistent results in comparison with those obtained by commercially available enzyme-linked immunosorbent assay kit.     

Detection of Babesia bovis Using DNA Hybridization1

ABSTRACT. Plasmids containing inserts of Babesia bovis DNA were prepared and clones suitable for use in the diagnosis of B. bovis infections were isolated. Dot blot hybridization with DNA from these plasmids, which probably contain repetitive sequences, can detect after an overnight exposure 100 pg of B. bovis DNA, which corresponds to the amount of DNA present in 50 μl of 0.01% parasitemic erythrocytes. No detectable cross-hybridization was observed with Babesia microti, Plasmodium falciparum, Plasmodium vivax, Boophilus, or cow DNA. A small amount of cross-hybridization was observed with 10 ng Babesia bigemina DNA. Use of these probes in a hybridization assay may be helpful in the diagnosis of babesiosis in cattle and ticks, in the confirmation of strain identities, and in correlating virulence with particular strains of Babesia.     

Sensitive and Label-Free Detection of DNA by Surface Plasmon Resonance

While an array of technologies based on radioactive labels or luminescent tags are dominant in modern biomedical research on DNA, surface plasmon resonance (SPR) and SPR imaging measurements are sensitive, rapid, and label-free. This review summarizes recent advances in the development of SPR and coupled techniques and their applications in DNA research, including the gene analysis at trace levels and studies of DNA–protein and DNA–drug interactions.     

Silicon Nitride-BP-Based Surface Plasmon Resonance Highly Sensitive Biosensor for Virus SARS-CoV-2 Detection

In this study, we propose a surface plasmon resonance (SPR)-based biosensor using silicon nitride (Si₃N₄), black phosphorous (BP), and thiol-tethered DNA as a ligand for fast detection of the SARS-CoV-2 virus. In the proposed biosensor, we have deposited silver (Ag), Si₃N₄, and BP on the base of the BK-7 prism and investigated the performance parameters on the probe in different combinations of the mentioned materials. Herein, three (Ag, Si₃N₄, and BP) different configurations are introduced and compared for the detection of SARS-CoV-2. Furthermore, with the help of the transfer matrix method (TMM), all the three configurations have been analyzed. Notably, the combination of Ag, Si₃N₄, and BP shows better sensitivity (154°/RIU) when compared with other configurations for the detection of SARS-CoV-2. This work may facilitate a new sensing device to detect SARS-CoV-2, based on the hybrid materials.

     

Highly Sensitive Dual-core Photonic Crystal Fiber Based on a Surface Plasmon Resonance Sensor with Gold Film

Plasmonics - A highly sensitive surface plasmon resonance (SPR) sensor comprising a dual-core photonic crystal fiber (PCF) is designed to detect minute changes in analyte refractive indices (RIs)...     

Highly Sensitive Surface Plasmon Resonance Biosensors Utilizing Prism-Waveguide Configuration for Detection of Alzheimer Disease Biomarker

Plasmonics - Alzheimer’s disease (AD) is a disease in cognitive regions in the human brain. Also the detection of AD in the early stage is too important. In this regard, a surface plasmon...     

Surface Plasmon Resonance Studies of the Hybridization Behavior of DNA-Modified Gold Nanoparticles with Surface-Attached DNA Probes

Colloidal gold nanoparticles (AuNPs) have been extensively investigated as amplification tags to improve the sensitivity of surface plasmon resonance (SPR) biosensors. When using the so-called AuNP-enhanced SPR technique for DNA detection, the density of single-stranded DNA (ssDNA) on both the AuNPs and planar gold substrates is of crucial importance. Thus, in this work, we carried out a systematical study about the influence of surface ssDNA density onto the hybridization behavior of various DNA-modified AuNPs (DNA-AuNPs) with surface-attached DNA probes by using surface plasmon resonance spectroscopy. The lateral densities of the ssDNA on both the AuNPs and planar gold substrates were controlled by using different lengths of oligo-adenine sequence (OAS) as anchoring group. Besides SPR measurements, the amount of the captured DNA-AuNPs after the hybridization was further identified via atomic force microscope (AFM). SPR and AFM results clearly indicated that a higher ssDNA density on either the AuNPs or the gold substrates would give rise to better hybridization efficiency. Moreover, SPR data showed that the captured DNA-AuNPs could not be removed from SPR sensor surfaces using various dehybridization solutions regardless of surface ssDNA density. Consequently, it is apparent that the hybridization behavior of DNA-AuNPs was different from that of solution-phase ssDNA. Based on these data, we hypothesized that both multiple recognitions and limited accessibility might account for the hybridization of DNA-AuNPs with surface-attached ssDNA probes.

     

Polarization-Dependent Resonance Light Scattering of Biomolecular Layer Coated Gold Nanoshell

Polarization-dependent resonance light scattering (RLS) of biomolecular layer coated gold nanoshell are investigated theoretically by means of the quasistatic approximation. Both the intensity and wavelength of RLS are sensitive to the azimuth angle and can be tuned by altering the core dielectric constant and biomolecular layer thickness. In the direction parallel to the incident polarization, RLS could be enhanced by decreasing the core dielectric constant or increasing the layer thickness whereas, in the direction perpendicular to the incident polarization, the RLS is only sensitive to the core dielectric constant. The variation of RLS corresponding to the changing of biomolecular layer thickness also greatly depends on the polarization. The variation of RLS intensity always reaches its maximum when the azimuth angle is 0 and can be improved by increasing the gold shell thickness or decreasing the core dielectric constant. However, the variation of RLS wavelength always reaches its maximum when the azimuth angle is between 0 and π/2 and can be improved by decreasing the gold shell thickness or core dielectric constant. This optimization of polarization-dependent RLS response of gold nanoshell to the biocoating is potentially useful in biosensing applications.     

One-Step Synthesis of Gold Nanoparticles Using Liquid Crystal Molecules for Surface-Enhanced Raman Scattering Detection

Plasmonics - Gold nanoparticles have received widespread attention as surface-enhanced Raman scattering (SERS) detection active substrates. In this work, we used the nematic liquid crystal molecule...     

应用树状DNA杂交(DDH)对生殖道尖锐湿疣中HPV DNA的分型检测

从手术切除的50例生殖道尖锐湿疣新鲜标本中,以及15例正常人血清中,提取基因组DNA,同时用树状DNA杂交(dendrimer DNA hybridizalion,DDH)技术和PCR进行HPV DNA的分型检测.结果50例尖锐湿疣中,以DDH方法检测,感染HPV6型者20例,感染11型者24例,6/11型混合感染者3例,阴性3例,总检测率达94%;以PCR方法检测,HPV6型感染者21例,11型感染者24例,6/11型混合感染者3例,阴性2例,总检测率为96%.15例正常人血清中,以DDH方法检测,HPV感染的假阳性率为0%;以PCR检测,假阳性率为6.67%.还以HPV阳性标本对DDH方法做了敏感度的测定,结果阳性病例DNA检测最低浓度为97.28pg/ml.研究表明,DDH技术具有较高敏感性和高特异性,且成本较低,操作安全简便,可适用于基层中小医院较大样本量筛查.     

Creatinine-Modified Gold Nanoparticles for Highly Sensitive Colorimetric Sensing of Nitroguanidine Explosive

Plasmonics - We report a simple, facile, selective, and highly sensitive colorimetric sensor for nitroguanidine explosive. The colorimetric sensor utilizes the aggregation of creatinine-modified...     

液相杂交快速检测特异DNA

检测特异DNA片段的方法中,传统Southern blot技术由于其高度可重复性及能够显示条带大小的特性,一直是DNA检测的“黄金标准”.但是杂交时间长,步骤复杂,放射性污染等问题亟待解决.为了简化Southern blot,研究使用了一种液相杂交快速检测DNA的方法,即使用异硫氰酸荧光素(FITC)标记的dUTP掺入探针后,在溶液中与待检测DNA样本42℃下杂交,然后琼脂糖凝胶电泳检测荧光杂交信号.利用质粒为模板,优化了探针制作、杂交液组成、杂交时间和温度等参数.在FITC-dUTP∶ dTTP比例为1∶3、模板质粒浓度为50μg、1×杂交缓冲液(25 mmol/LTris,10mmol/L EDTA,8mmol/L Nacl,PH =8.0)中95℃变性5～9 min和42℃杂交3h的实验条件下,可检出1.2μg的质粒,探针灵敏度为7.3 ng/μl.这种方法不需要转膜,曝光,大大节约了时间,简化了操作,荧光检测也为该方法同时检测多色样本提供了可能,可广泛应用于核酸检测.     

Localized Surface Plasmon Resonance (LSPR) Detection of Diphtheria Toxoid Using Gold Nanoparticle-Monoclonal Antibody Conjugates

Plasmonics - Detection of diphtheria toxin (DT) which is produced by Corynebacterium diphtheria, a zoonotic pathogen and a leading cause of diphtheria, is the critical step in the clinical...     

高灵敏荧光探针用于肿瘤 Ramos 细胞的快速检测

本文以聚苯乙烯纳米微球为载体,基于适体特异性识别和 DNA 杂交原理,组装了一种 DNA-CdTe 量子点纳米线,制备了具有较高荧光强度的复合型荧光探针,并成功用于 Ramos 细胞的荧光成像。该探针可以用于特异性识别肿瘤细胞,在荧光成像中信号强灵敏度高,为肿瘤细胞的检测提供一种新方法。