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Zhijun Li, Kim A Munro, Mina Narouz, Bin Hao, Cathleen M Crudden, J Hugh Horton, Hongxia Hao
Surface chemistry is a key enabler for various biosensing applications. Surface plasmon resonance (SPR)-based biosensors 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...
October 19, 2017: ACS Applied Materials & Interfaces
N Dorh, A Sarua, T Ajmal, J Okache, C Rega, G M Müller, M J Cryan
This paper presents measured fluorescence enhancement results for ∼250×250 element aluminum nanoantenna arrays fabricated using electron beam lithography. The arrays have been designed to use diffractive coupling to enhance and control the direction of fluorescent emission. Highly directional emission is obtained at the designed angles with beam widths simulated to be in the range of 4-6°. Angle-resolved spectroscopy measurements of dye-coated nanoantenna arrays were in good agreement with finite difference time domain modeling...
October 10, 2017: Applied Optics
Tianxiang Wei, Tingting Dong, Hong Xing, Ying Liu, Zhihui Dai
To achieve high selectivity and sensitivity simultaneously in an electrochemical biosensing platform, cucurbituril and azide co-functionalized graphene oxide, a new functional nanomaterial that acts as a go-between to connect the recognition element with amplified signal architecture, is developed in this work. The cucurbituril and azide co-functionalized graphene oxide features a high specific surface area with abundant levels of the two types of functional groups. Specifically, it emerges as a powerful tool to link recognition elements with simplicity, high yield, rapidity and highly selective reactivity through azide-alkynyl click chemistry...
October 18, 2017: Analytical Chemistry
Ahmed Abumazwed, Wakana Kubo, Takuo Tanaka, Andrew G Kirk
We present a novel approach to improve self-referenced sensing based on multiple-resonance nanorod structures. The method employs the maximum likelihood estimation (MLE) alongside a linear response model (LM), relating the sensor response (shifts in resonance wavelengths) to the changes due to surface binding and bulk refractive index. We also provide a solution to avoid repetitive simulations, that have been previously needed to determine the adlayer thickness sensitivity when measuring biological samples of different refractive indices...
October 2, 2017: Optics Express
Mateusz Śmietana, Monika Janik, Marcin Koba, Wojtek J Bock
In this work we discuss the refractive index (RI) sensitivity of a micro-cavity in-line Mach-Zehnder interferometer in the form of a cylindrical hole (40-50 μm in diameter) fabricated in a standard single-mode optical fiber using a femtosecond laser. The surface of the micro-cavity was coated with up to 400 nm aluminum oxide thin film using the atomic layer deposition method. Next, the film was progressively chemically etched and the influence on changes in the RI of liquid in the micro-cavity was determined at different stages of the experiment, i...
October 16, 2017: Optics Express
Jean-Patrick Francoia, Laurent Vial
Less than a decade ago, dendrigrafts of poly-L-lysine (DGLs) joined the family of polycationic dendritic macromolecules. Resulting from the iterative polycondensation of a N-carboxyanhydride in water, four generations of the dendrigraft can be obtained on a multi-gram scale and without chromatographic purification. DGLs share features with both dendrimers and hyperbranched polymers, but turned out to have unique biophysical and bioactive properties. The macromolecules - in their native form or functionalized - have been extensively characterized by various analytical and computational methods, and already found numerous applications in the biomedical field such as drug and gene delivery, biomaterials, tissue engineering, bioimaging, and biosensing...
October 16, 2017: Chemistry: a European Journal
Panpan Gai, Chengcheng Gu, Haiyin Li, Xinzhi Sun, Feng Li
A new label-free and enzyme-free ratiometric homogeneous electrochemical microRNA biosensing platform was constructed via target-triggered Ru(III) release and redox recycling. To design the effective ratiometric dual-signal strategy, [Ru(NH3)6](3+) (Ru(III)) as one of electroactive probe was ingeniously entrapped in the pores of positively charged mesoporous silica nanoparticle (PMSN), as well as another electroactive probe [Fe(CN)6](3-) (Fe(III)) was selected to facilitate Ru(III) redox reclycling due to their distinctly separated reduction potential and different redox properties...
October 16, 2017: Analytical Chemistry
Pei-Han Liu, Pawel L Urban
The temporal effects of luciferase reaction luminescence have only been discussed in the context of light intensity (flash vs. glow). However, alterations in the color of the light emitted over the course of the luciferase reaction have not been reported. Here, we show a temporal change in the light color emitted during the reaction catalyzed by unmodified firefly luciferase when concentrations of one of the substrates, adenosine triphosphate (ATP), are gradually increased. The temporal color change from green to red occurs within the first few minutes of the luciferase reaction when an ATP-containing solution is either added or synthesized in situ with the aid of an autocatalytic reaction occurring simultaneously...
October 10, 2017: Analytical Biochemistry
Qiu-Mei Feng, Yue-Hua Guo, Jing-Juan Xu, Hong-Yuan Chen
A critical challenge in surface-based DNA assembly amplification is the reduced accessibility of DNA strands arranged on a heterogeneous surface compared to that in homogeneous solution. Here, a novel in situ surface-confined DNA assembly amplification electrochemiluminescence (ECL) biosensor based on DNA nanostructural scaffold was presented. In this design, a stem-loop structural DNA segment (Hairpin 1) was constructed on the vertex of DNA nanostructural scaffold as recognition probe. In the present of target DNA, the hairpin structure changed to rod-like through complementary hybridization with target DNA, resulting in the formation of Hairpin 1:target DNA...
September 22, 2017: Biosensors & Bioelectronics
Jaewook Lee, Kenshin Takemura, Enoch Y Park
Plasmonic nanomaterials (P-NM) are receiving attention due to their excellent properties, which include surface-enhanced Raman scattering (SERS), localized surface plasmon resonance (LSPR) effects, plasmonic resonance energy transfer (PRET), and magneto optical (MO) effects. To obtain such plasmonic properties, many nanomaterials have been developed, including metal nanoparticles (MNP), bimetallic nanoparticles (bMNP), MNP-decorated carbon nanotubes, (MNP-CNT), and MNP-modified graphene (MNP-GRP). These P-NMs may eventually be applied to optical biosensing systems due to their unique properties...
October 13, 2017: Sensors
Tanzilur Rahman, Takanori Ichiki
The fabrication of miniaturized electrical biosensing devices can enable the rapid on-chip detection of biomarkers such as miRNA molecules, which is highly important in early-stage cancer detection. The challenge in realizing such devices remains in the miniaturization of the reference electrodes, which is an integral part of electrical detection. Here, we report on a novel thin film Ag/AgCl reference electrode (RE) that has been fabricated on top of a Au-sputtered glass surface, which was coated with a self-assembled monolayer (SAM) of 6-mercepto-1-hexanol (MCH)...
October 13, 2017: Sensors
Zhimin Chai, Cihan Yilmaz, Ahmed Busnaina, Charles A Lissandrello, David J D Carter
Printing nano and microscale three-dimensional (3D) structures using directed assembly of nanoparticles has many potential applications in electronics, photonics and biotechnology. This paper presents a reproducible and scalable 3D dielectrophoresis assembly process for printing homogeneous silica and hybrid silica/gold nanorods from silica and gold nanoparticles. The nanoparticles are assembled into patterned vias under a dielectrophoretic force generated by an alternating current (AC) field, and then completely fused in situ to form nanorods...
October 13, 2017: Nanotechnology
D Caballero, S Kaushik, V M Correlo, J M Oliveira, R L Reis, S C Kundu
Most cancer patients do not die from the primary tumor but from its metastasis. Current in vitro and in vivo cancer models are incapable of satisfactorily predicting the outcome of various clinical treatments on patients. This is seen as a serious limitation and efforts are underway to develop a new generation of highly predictive cancer models with advanced capabilities. In this regard, organ-on-chip models of cancer metastasis emerge as powerful predictors of disease progression. They offer physiological-like conditions where the (hypothesized) mechanistic determinants of the disease can be assessed with ease...
October 3, 2017: Biomaterials
Christoph Bernhard, Steven J Roeters, Johannes Franz, Tobias Weidner, Mischa Bonn, Grazia Gonella
Development of new materials for drug delivery and biosensing requires the fine-tuning of interfacial properties. We report here the influence of the poly(ethylene glycol) (PEG) grafting density in model phospholipid monolayers on the adsorption behavior of bovine serum albumin and human fibrinogen, not only with respect to the amount of adsorbed protein, but also its orientational ordering on the surface. As expected, with increasing interfacial PEG density, the amount of adsorbed protein decreases up to the point where complete protein repellency is reached...
October 12, 2017: Physical Chemistry Chemical Physics: PCCP
Zhanxi Fan, Xiao Huang, Ye Chen, Wei Huang, Hua Zhang
Gold (Au) nanomaterials have attracted wide research attention, owing to their high chemical stability, promising catalytic properties, excellent biocompatibility, unique electronic structure and outstanding localized surface plasmon resonance (LSPR) absorption properties; all of which are closely related to their size and shape. Recently, crystal-phase-controlled synthesis of noble metal nanomaterials has emerged as a promising strategy to tune their physicochemical properties. This protocol describes the detailed experimental procedures for the crystal-phase-controlled syntheses of Au nanomaterials with unusual crystal structures under mild conditions...
November 2017: Nature Protocols
Brian M Dincau, Yongkuk Lee, Jong-Hoon Kim, Woon-Hong Yeo
Early disease diagnostics require rapid, sensitive, and selective detection methods for target analytes. Specifically, early viral detection in a point-of-care setting is critical in preventing epidemics and the spread of disease. However, conventional methods such as enzyme-linked immunosorbent assays or cell cultures are cumbersome and difficult for field use due to the requirements of extensive lab equipment and highly trained personnel, as well as limited sensitivity. Recent advances in nanoparticle concentration have given rise to many novel detection methodologies, which address the shortcomings in modern clinical assays...
October 11, 2017: Sensors
Juliane R Sempionatto, Rupesh K Mishra, Aida Martín, Guangda Tang, Tatsuo Nakagawa, Xiaolong Lu, Alan S Campbell, Kay Mengjia Lyu, Joseph Wang
This work describes a wireless wearable ring-based multiplexed chemical sensor platform for rapid electrochemical monitoring of explosive and nerve-agent threats in vapor and liquid phases. The ring-based sensor system consists of two parts: a set of printed electrochemical sensors and a miniaturized electronic interface, based on a battery-powered stamp-size potentiostat, for signal processing and wireless transmission of data. A wide range of electrochemical capabilities have thus been fully integrated into a 3D printed compact ring structure, toward performing fast square-wave voltammetry and chronoamperometric analyses, along with interchangeable screen-printed sensing electrodes for the rapid detection of different chemical threats...
October 11, 2017: ACS Sensors
Yi-Ting Chen, Arati G Kolhatkar, Oussama Zenasni, Shoujun Xu, T Randall Lee
Magnetic particles are widely used as signal labels in a variety of biological sensing applications, such as molecular detection and related strategies that rely on ligand-receptor binding. In this review, we explore the fundamental concepts involved in designing magnetic particles for biosensing applications and the techniques used to detect them. First, we briefly describe the magnetic properties that are important for bio-sensing applications and highlight the associated key parameters (such as the starting materials, size, functionalization methods, and bio-conjugation strategies)...
October 10, 2017: Sensors
Xiang Ren, Hongmin Ma, Tong Zhang, Yong Zhang, Tao Yan, Bin Du, Qin Wei
The accurate tumor marker detection at early stage can prevent people from getting cancer to a great extent. Herein, a novel tri-antibody dual-channel biosensing strategy is applied in multianalysis of carcino-embryonic antigen (CEA) and nuclear matrix protein 22 (NMP22). In this immunosensor fabrication process, graphene oxide/polyaniline nanostructures are used as matrix and mesoporous NKF-5-3 is used as labels. Two kind antigens can be obtained from the signals of neutral red and toluidine blue, respectively, which are modified on the labels...
October 10, 2017: ACS Applied Materials & Interfaces
Md Masud Parvez Arnob, Wei-Chuan Shih
No abstract text is available yet for this article.
October 10, 2017: Nanomedicine
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