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    Surface Plasmon Resonance Aptamer Biosensor for Discriminating Pathogenic Bacteria . Ahn Ji-Young,Lee Kyeong-Ah,Lee Moon-Jong,Sekhon Simranjeet Singh,Rhee Sung-Keun,Cho Sung-Jin,Ko Jung Ho,Lee Lyon,Han Janet,Kim Sang Yong,Min Jiho,Kim Yang-Hoon Journal of nanoscience and nanotechnology In this paper, whole-bacteria SELEX (WB-SELEX) strategy was adopted to isolate specific aptamers against Vibrio parahaemolyticus. Round selection for V. parahaemolyticus was conducted 11 rounds, including two negative selection rounds. It was determined through real-time PCR amplification and post-SELEX experiment. The selected aptmers had high binding property and specificity to V. parahaemolyticus. Of 28 aptamers tested, VPCA-apta#1 had the highest binding affinity compared to other aptamer candidates obtained. To detect V. parahaemolyticus, aptamer based SPR biosensor platform was constructed and pathogenic bacteria sensing was conducted in two steps. The first step was to construct 5'-biotinylated VPCA-apta#1 binding probe. The second step was to incubate V. parahaemolyticus and test microbes in functionalized SA sensor chip in parallel. Our platform showed significant activity for detecting and discriminating V. parahaemolyticus from other enteric species such as Escherichia coli, Listeria monocytogenes, Sigella sonnei, and Vibrio fischeri. This is the first report on the use of whole-SELEX to isolate DNA aptamers specific for V. parahaemolyticus. We demonstrated the feasibility of using aptamer platform for the detection of V. parahaemolyticus in various food supplies. It might be used in multiple points of care for diagnosing Vibriosis. 10.1166/jnn.2018.14212
    Analysis of Mycotoxins in Beer Using a Portable Nanostructured Imaging Surface Plasmon Resonance Biosensor. Joshi Sweccha,Annida Rumaisha M,Zuilhof Han,van Beek Teris A,Nielen Michel W F Journal of agricultural and food chemistry A competitive inhibition immunoassay is described for the mycotoxins deoxynivalenol (DON) and ochratoxin A (OTA) in beer using a portable nanostructured imaging surface plasmon resonance (iSPR) biosensor, also referred to as imaging nanoplasmonics. The toxins were directly and covalently immobilized on a 3-dimensional carboxymethylated dextran (CMD) layer on a nanostructured iSPR chip. The assay is based on competition between the immobilized mycotoxins and free mycotoxins in the solution for binding to specific antibodies. The chip surface was regenerated after each cycle, and the combination of CMD and direct immobilization of toxins allowed the chips to be used for more than 450 cycles. The limits of detection (LODs) in beer were 17 ng/mL for DON and 7 ng/mL for OTA (or 0.09 ng/mL after 75 times enrichment). These LODs allowed detection of even less than 10% depletion of the tolerable daily intake of DON and OTA by beer. Significant cross-reactivity of anti-DON was observed toward DON-3-glucoside and 3-acetyl-DON, while no cross-reactivity was seen for 15-acetyl-DON. A preliminary in-house validation with 20 different batches of beer showed that both toxins can be detected at the considered theoretical safe level for beer. The assay can be used for in-field or at-line detection of DON in beer and also in barley without preconcentration, while OTA in beer requires an additional enrichment step, thus making the latter in its present form less suitable for field applications. 10.1021/acs.jafc.6b04106
    A surface plasmon resonance immunoassay for the rapid analysis of methamphetamine in forensic oral fluid. Wang Jiye,Yao Weixuan,Meng Fanwei,Wang Pengjuan,Wu Yuanzhao,Wang Binjie Journal of clinical laboratory analysis BACKGROUND:Current chromatographic methods applied for the forensic analysis of methamphetamine are costly, time-consuming, and require complicated pretreatment procedures. Thus, the rapid detection of methamphetamine is a critical and unmet need. In this study, a surface plasmon resonance (SPR) system based on indirect inhibitive immunoassay was designed for the analysis of methamphetamine in forensic oral fluid samples. METHODS:For the inhibition immunoassay, the diluted oral fluid was mixed with methamphetamine antibody and then injected into the SPR sensor chip. The biosensor chip was constructed by covalently immobilizing of methamphetamine-bovine serum albumin conjugate onto a carboxymethyl dextran surface at an optimized pH. The concentration of antibody was also optimized. RESULTS:The SPR biosensor showed good sensitivity with a limit of detection of 0.44 ng/mL and was comparable or lower than the pre-existing methods. The method was finally tested using oral fluid samples from 20 suspected drug abusers in forensic cases, and it provided an acceptable recovery of 113.2%, indicating good anti-interference capability of the SPR sensor. CONCLUSION:The SPR biosensor was rapid, reproducible, and had a great potential approach for the forensic detection of methamphetamine. 10.1002/jcla.22993
    A biosensor for determination of the circulating biomarker CA125/MUC16 by Surface Plasmon Resonance Imaging. Szymańska B,Lukaszewski Z,Hermanowicz-Szamatowicz K,Gorodkiewicz E Talanta CA125/MUC16 is an ovarian tumor cell marker widely used as a biomarker in epithelial ovarian carcinoma. CA125/MUC16 is also used for evaluation of the ROMA (Risk of Ovarian Malignancy Algorithm) value. In this work, a Surface Plasmon Resonance Imaging (SPRI) biosensor for circulating CA125/MUC16 has been developed. The anti-MUC16 antibody was attached to a gold chip via a cysteamine linker. The EDS/NHS protocol was used for the covalent attachment of the antibody. The developed biosensor is specific for CA125/MUC16, and exhibits good recovery and acceptable precision. Its linear response range (2.2-150 U/ml) is well suited to determination of the marker in the blood serum of a healthy control group and, after appropriate dilution, of patients with ovarian cancer. CA125/MUC16 was determined in two series of real samples: blood serum from patients with ovarian cancer and endometrial cysts. The method was validated by parallel determination of the samples using the chemiluminescent Architect i2000 method. 10.1016/j.talanta.2019.120187
    Lipopolysaccharides detection on a grating-coupled surface plasmon resonance smartphone biosensor. Zhang Jinling,Khan Imran,Zhang Qingwen,Liu Xiaohu,Dostalek Jakub,Liedberg Bo,Wang Yi Biosensors & bioelectronics We report a smartphone label-free biosensor platform based on grating-coupled surface plasmon resonance (GC-SPR). The sensor system relies on the smartphone's built-in flash light source and camera, a disposable sensor chip with Au diffraction grating and a compact disk (CD) as the spectra dispersive unit. The Au grating sensor chip was modified with a synthetic peptide receptor and employed on the GC-SPR detection of lipopolysaccharides (known as endotoxins) with detection limit of 32.5ng/mL in water. Upon incubation of various small and macro-molecules with the synthetic peptide modified sensor chips, we concluded the good selectivity of the sensor for LPS detection. In addition, the sensor shows feasibility for the detection of LPS in commonly used clinical injectable fluids, such as clinical-grade 0.9% sodium chloride intravenous infusion, compound sodium lactate intravenous infusion and insulin aspart. The developed sensor platform offers the advantage of portability and simplicity, which is attractive for point-of-care and remote detection of biomedical and environmental targets. 10.1016/j.bios.2017.07.048
    Carboxymethylated Dextran-Modified N-Heterocyclic Carbene Self-Assembled Monolayers on Gold for Use in Surface Plasmon Resonance Biosensing. Li Zhijun,Narouz Mina R,Munro Kim,Hao Bin,Crudden Cathleen M,Horton J Hugh,Hao Hongxia ACS applied materials & interfaces Surface chemistry is a key enabler for various biosensing applications. Biosensors based on surface plasmon resonance routinely employ thiol-based chemistry for the linker layer between gold-coated support surfaces and functional biosensor surfaces. However, there is a growing awareness that such sensor surfaces are prone to oxidation/degradation problems in the presence of oxygen, and previous efforts to improve the stability have shown limited advancements. As an alternative, recent studies employing N-heterocyclic carbene (NHC) self-assembled monolayers (SAMs) deposited on gold have shown significant promise in this area. Here, we describe a sensor surface employing an NHC SAM to couple a modified carboxymethylated dextran onto a gold surface. Such a dextran matrix is also used for affinity chromatography, and it is the most commonly employed matrix for commercial biosensor surfaces today. The performance reliability of the dextran-modified NHC chip to act as an alternative biosensing platform is compared with that of a thiol-based commercial chip in the proof-of-concept tests. The resultant NHC sensor surface shows a higher thermal stability compared to thiol analogues. Moreover, the plasma protein/drug and antibody/antigen interactions were validated on the NHC-based dextran chip and showed similar performance as compared to the thiol-based commercial chip. Ultimately, this study shows the strong potential applicability of chemical modifications to gold surfaces using NHC ligands for biosensing applications. 10.1021/acsami.7b13114
    Point-of-Care Surface Plasmon Resonance Biosensor for Stroke Biomarkers NT-proBNP and S100β Using a Functionalized Gold Chip with Specific Antibody. Harpaz Dorin,Koh Brescia,Marks Robert S,Seet Raymond C S,Abdulhalim Ibrahim,Tok Alfred I Y Sensors (Basel, Switzerland) Surface-plasmon-resonance (SPR) is a quantum-electromagnetic phenomenon arising from the interaction of light with free electrons at a metal-dielectric interface. At a specific angle/wavelength of light, the photon's energy is transferred to excite the oscillation of the free electrons on the surface. A change in the refractive-index (RI) may occur, which is influenced by the analyte concentration in the medium in close contact with the metal surface. SPR has been widely used for the detection of gaseous, liquid, or solid samples. In this study, a functionalized specific SPR chip was designed and used in a novel point-of-care SPR module (PhotonicSys SPR H5) for the detection of the stroke biomarkers NT-proBNP and S100β. These biomarkers have proven to be good for stroke diagnosis, with sensitivity and specificity of >85%. Specific detection was done by binding a biomolecular-recognizing antibody onto the Au SPR-chip. Detection was tested in water and plasma samples. NT-proBNP and S100β were detected in a range of concentrations for stroke, from 0.1 ng/mL to 10 ng/mL. The RI of the blank plasma samples was 1.362412, and the lowest concentration tested for both biomarkers showed a prominent shift in the RI signal (0.25 ng/mL NT-proBNP (1.364215) and S100β (1.364024)). The sensor demonstrated a clinically relevant limit-of-detection of less than ng/mL. 10.3390/s19112533
    A label-free ultrasensitive microfluidic surface Plasmon resonance biosensor for Aflatoxin B detection using nanoparticles integrated gold chip. Bhardwaj Hema,Sumana Gajjala,Marquette Christophe A Food chemistry The Surface Plasmon resonance (SPR) based label-free detection of small targeted molecules is a great challenge and require substantial signal amplification for the accurate and precise quantification. The incorporation of noble metal nanoparticles (NPs) like gold (Au) NPs for the fabrication of SPR biosensor has shown remarkable impact both for anchoring the signal amplification and generate plasmonic resonant coupling between NPs and chip surface. In this work, we present comparative studies related to the fabrication of self-assembled monolayer (SAM) and the influence of AuNPs on Au chip for Aflatoxin B (AFB) detection using SPRi apparatus. The SAM Au chip was sequentially modified by EDC-NHS crosslinkers, grafting of protein-A and finally interaction with anti-AFB antibodies. Similar multilayer chip surface was prepared using functionalized lipoic acid AuNPs deposited on SAM Au chips followed by in situ activation of functional groups using EDC-NHS crosslinkers, grafting of protein-A and immobilization of anti-AFB antibodies. This multilayer functionalized AuNPs modified Au chip was successfully utilized for AFB detection ranging from 0.01 to 50 nM with a limit of detection of 0.003 nM. When compared to bare self-assembled Au chip which was shown to exhibit a limit of detection of 0.19 nM and a linear detection ranging from 1 to 50 nM, the AuNPs modified Au chip was proven to clearly be a better analytical tool. Finally, validation of the proposed biosensor was evaluated by spiked wheat samples and average recoveries (93 and 90.1%) were found to be acceptable. 10.1016/j.foodchem.2019.125530
    Surface plasmon resonance biosensor for the accurate and sensitive quantification of O-GlcNAc based on cleavage by β-D-N-acetylglucosaminidase. Gao Li,Zhao Ruihuan,Wang Yiwen,Lu Mei,Yang Dingding,Fa Mengmei,Yao Xin Analytica chimica acta Abnormal O-linked-N-acetylglucosamine (O-GlcNAc) concentrations have been associated with a variety of diseases (e.g., cancer, Alzheimer's disease, cardiovascular disease, etc.). However, O-GlcNAc detection is complicated, time-consuming and has poor specificity, therefore, the accurate detection of O-GlcNAc is difficult. In this study, an accurate and sensitive surface plasmon resonance (SPR) biosensor for O-GlcNAc detection that is based on β-D-N-acetylglucosaminidase (OGA) and Au nanoparticles (AuNPs) was developed. In this strategy, AuNPs were used to amplify the SPR signal and improve the biosensor's sensitivity; OGA was used to cleave O-GlcNAc from O-GlcNAcylated biomolecules. The interaction between AuNPs labeled wheat germ agglutinin (AuNPs/WGA) and O-GlcNAcylated biomolecules on a modified Au film treated with and without OGA was recorded by SPR. The change of the SPR signal moves linearly with the amount of O-GlcNAc on the Au film and thus could be used for the detection of O-GlcNAc. By recording the difference of the SPR signals, this method can avoid disturbances from other sugars and nonspecific adsorption of AuNPs and thus enable the accurate detection of O-GlcNAc. The accurate detection range of O-GlcNAc was 4.65 × 10 to 4.65 × 10 M which was obtained by quantifying the amount of a standard O-GlcNAcylated peptide (O-GlcNAc-CREB), and the detection limit is 4.65 × 10 M. More importantly, the strategy was successfully used to detect O-GlcNAc in a real α-crystallin protein, cancer cell lysates and blood samples with satisfactory results. The study's results imply that this accurate and sensitive method has the potential to be applied in the early clinical diagnosis of O-GlcNAc-related diseases. 10.1016/j.aca.2018.07.058
    Electrochemically enhanced antibody immobilization on polydopamine thin film for sensitive surface plasmon resonance immunoassay. Chen Daqun,Mei Yihong,Hu Weihua,Li Chang Ming Talanta For sensitive immunoassay, it is essentially important to immobilize antibody on a surface with high density and full retention of their recognition activity. Bio-inspired polydopamine (PDA) thin film has been widely utilized as a reactive coating to immobilize antibody on various surfaces. We herein report that the antibody immobilization capacity of PDA thin film is electrochemically enhanced by applying an oxidative potential to convert the surface catechol group to reactive quinone group. Quantitative surface plasmon resonance (SPR) investigation unveils that upon proper electrochemical oxidization, the antibody loading capacity of PDA film is significantly improved (up to 27%) and is very close to the theoretically maximal capacity of a planar surface if concentrated antibody solution is used. Using prostate-specific antigen (PSA) as a model target, it is further demonstrated that the SPR immunoassay sensitivity is greatly enhanced due to the improved antibody immobilization. This work offers an efficient strategy to enhance the reactivity of PDA film towards nucleophiles, and may also facilitate its immunoassay application among others. 10.1016/j.talanta.2018.02.038
    A novel surface plasmon resonance biosensor based on the PDA-AgNPs-PDA-Au film sensing platform for horse IgG detection. Wang Ning,Zhang Di,Deng Xinyu,Sun Ying,Wang Xinghua,Ma Pinyi,Song Daqian Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Herein we report a novel polydopamine-silver nanoparticle-polydopamine-gold (PDA-AgNPs-PDA-Au) film based surface plasmon resonance (SPR) biosensor for horse IgG detection. The PDA-AgNPs-PDA-Au film sensing platform was built on Au-film via layer-by-layer self-assembly. Ag ion was reduced in situ to AgNPs in presence of PDA. The top PDA layer can prevent AgNPs from being oxidized and connect with antibody via Schiff alkali reaction directly. The morphology and thickness of the modified gold film were characterized using scanning electron microscope and Talystep. Experimental results show that the PDA-AgNPs-PDA-Au film sensing platform is stable, regenerative and sensitive for horse IgG detection. The detection limit of horse IgG obtained with the present biosensor is 0.625μgmL, which is 2-fold and 4-fold lower than that obtained with biosensor based on PDA modified Au film and conventional biosensor based on MPA, respectively. Furthermore, when challenged to real serum samples, our sensor exhibited excellent specificity to horse IgG, suggesting its potential for industrial application. 10.1016/j.saa.2017.10.039
    Electrochemical and surface plasmon resonance characterization of beta-cyclodextrin-based self-assembled monolayers and evaluation of their inclusion complexes with glucocorticoids. Frasconi Marco,Mazzei Franco Nanotechnology This paper describes the characterization of a self-assembled beta-cyclodextrin (beta-CD)-derivative monolayer (beta-CD-SAM) on a gold surface and the study of their inclusion complexes with glucocorticoids. To this aim the arrangement of a self-assembled beta-cyclodextrin-derivative monolayer on a gold surface was monitored in situ by means of surface plasmon resonance (SPR) spectroscopy and double-layer capacitance measurements. Film thickness and dielectric constant were evaluated for a monolayer of beta-CD using one-color-approach SPR. The selectivity of the beta-CD host surface was verified by using electroactive species permeable and impermeable in the beta-CD cavity. The redox probe was selected according to its capacity to permeate the beta-CD monolayer and its electrochemical behavior. In order to evaluate the feasibility of an inclusion complex between beta-CD-SAM with some steroids such as cortisol and cortisone, voltammetric experiments in the presence of the redox probes as molecules competitive with the steroids have been performed. The formation constant of the surface host-guest by beta-CD-SAM and the steroids under study was calculated. 10.1088/0957-4484/20/28/285502