scholarly journals Experimental study of an evanescent-field biosensor based on 1D photonic bandgap structures

2019 ◽  
Vol 10 ◽  
pp. 967-974
Author(s):  
Jad Sabek ◽  
Francisco Javier Díaz-Fernández ◽  
Luis Torrijos-Morán ◽  
Zeneida Díaz-Betancor ◽  
Ángel Maquieira ◽  
...  
Keyword(s):  
Binding Sites ◽  
Photonic Bandgap ◽  
Near Field ◽  
Evanescent Field ◽  
Label Free ◽  
Target Analytes ◽  
Label Free Detection ◽  
Exponential Decrease ◽  
Structure Surface ◽  
Photonic Bandgap Structures

A photonic bandgap (PBG) biosensor has been developed for the label-free detection of proteins. As the sensing in this type of structures is governed by the interaction between the evanescent field going into the cladding and the target analytes, scanning near-field optical microscopy has been used to characterize the profile of that evanescent field. The study confirms the strong exponential decrease of the signal as it goes into the cladding. This means that biorecognition events must occur as close to the PBG structure surface as possible in order to obtain the maximum sensing response. Within this context, the PBG biosensor has been biofunctionalized with half-antibodies specific to bovine serum albumin (BSA) using a UV-induced immobilization procedure. The use of half-antibodies allows one to reduce the thickness of the biorecognition volume down to ca. 2.5 nm, thus leading to a higher interaction with the evanescent field, as well as a proper orientation of their binding sites towards the target sample. Then, the biofunctionalized PBG biosensor has been used to perform a direct and real-time detection of the target BSA antigen.

scholarly journals Paper-based fluorogenic RNA aptamer sensors for label-free detection of small molecules

2020 ◽  
Vol 12 (21) ◽  
pp. 2674-2681
Author(s):  
Fatemeh Shafiei ◽  
Kathleen McAuliffe ◽  
Yousef Bagheri ◽  
Zhining Sun ◽  
Qikun Yu ◽  
...  
Keyword(s):  
Small Molecules ◽  
Rapid Detection ◽  
Rna Aptamer ◽  
Label Free ◽  
Target Analytes ◽  
Label Free Detection

A paper-based portable fluorogenic RNA sensor for the selective, sensitive, and rapid detection of target analytes.

scholarly journals A Fabry-Pérot cavity coupled surface plasmon photodiode for electrical biomolecular sensing

2021 ◽  
Author(s):  
Giles Allison ◽  
Amrita Sana ◽  
Yuta Ogawa ◽  
Hidemi Kato ◽  
Kosei Ueno ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
Specular Reflection ◽  
Incident Light ◽  
Near Field ◽  
Photovoltaic Cell ◽  
Plasmon Mode ◽  
Label Free ◽  
Plasmonic Sensor ◽  
Label Free Detection ◽  
Fabry Perot

Abstract Surface plasmon resonance (SPR) is a well-established technology for real-time highly sensitive label-free detection and measurement of binding kinetics between biological samples. A common drawback, however, of SPR detection is the necessity for far field angular resolved measurement of specular reflection, which increases the size as well as requiring precise calibration of the optical apparatus. Here we present an alternative optoelectronic approach in which the plasmonic sensor is integrated within a photovoltaic cell. Incident light generates an electronic signal that is sensitive to the refractive index (RI) of a solution via interaction with the plasmon. The photogenerated current is enhanced due to the coupling of the plasmon mode with Fabry-Pérot (FP) modes in the absorbing layer of the photovoltaic cell. The near field electrical detection of SPR we demonstrate will enable a new generation of cheap, compact and high throughput biosensors.

Tubular waveguide evanescent field absorption biosensor based on particle plasmon resonance for multiplex label-free detection

2013 ◽  
Vol 41 ◽  
pp. 268-274 ◽  
Author(s):  
Hsing-Ying Lin ◽  
Chen-Han Huang ◽  
Shin-Huei Chen ◽  
Yu-Chia Liu ◽  
Wei-Zhe Chang ◽  
...  
Keyword(s):  
Plasmon Resonance ◽  
Evanescent Field ◽  
Label Free ◽  
Label Free Detection ◽  
Particle Plasmon

scholarly journals An engineered one-site aptamer with higher sensitivity for label-free detection of adenosine on graphene oxide

2018 ◽  
Vol 96 (11) ◽  
pp. 957-963 ◽  
Author(s):  
Zijie Zhang ◽  
Juewen Liu
Keyword(s):  
Graphene Oxide ◽  
Binding Sites ◽  
Dna Aptamer ◽  
Stem Length ◽  
Titration Calorimetry ◽  
Label Free ◽  
Label Free Detection ◽  
Analytical Perspective ◽  
Target Binding ◽  
The One

The 27-nucleotide DNA aptamer for adenosine and ATP, originally selected by the Szostak lab in 1995, has been a very popular model system for biosensor development. This unique aptamer has two target binding sites, and we recently showed that it is possible to remove either site while the other one still retains binding. From an analytical perspective, tuning the number of binding sites has important implications in modulating sensitivity of the resulting biosensors. In this work, we report that the engineered one-site aptamer showed excellent signaling properties with a 2.6-fold stronger signal intensity and also a 4.2-fold increased detection limit compared with the wild-type two-site aptamer. The aptamer has a hairpin structure, and the length of the hairpin stem was systematically varied for the one-site aptamers. Isothermal titration calorimetry and a label-free fluorescence signaling method with graphene oxide and SYBR Green I were respectively used to evaluate binding and sensor performance. Although longer stemmed aptamers produced better adenosine binding affinity, the signaling was quite independent of the stem length as long as more than three base pairs were left. This was explained by the higher affinity of binding to GO by the longer aptamers, cancelling out the higher affinity for adenosine binding. This work further confirms the analytical applications of such one-site adenosine aptamers, which are potentially useful for improved ATP imaging and for developing new biosensors.

scholarly journals Quantitative Surface Plasmon Interferometry via Upconversion Photoluminescence Mapping

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Anxiang Yin ◽  
Hao Jing ◽  
Zhan Wu ◽  
Qiyuan He ◽  
Yiliu Wang ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
Incident Light ◽  
Near Field ◽  
Specific Antigen ◽  
Far Field ◽  
Label Free ◽  
Environment Change ◽  
Label Free Detection ◽  
Rare Earth Doped

Direct far-field visualization and characterization of surface plasmon polaritons (SPPs) are of great importance for fundamental studies and technological applications. To probe the evanescently confined plasmon fields, one usually requires advanced near-field techniques, which is typically not applicable for real-time, high-throughput detecting or mapping of SPPs in complicated environments. Here, we report the utilization of rare-earth-doped nanoparticles to quantitatively upconvert invisible, evanescently confined SPPs into visible photoluminescence emissions for direct far-field visualization of SPPs in a complicated environment. The observed interference fringes between the SPPs and the coherent incident light at the metal surface provide a quantitative measurement of the SPP wavelength and the SPP propagating length and the local dielectric environments. It thus creates a new signaling pathway to sensitively transduce the local dielectric environment change into interference periodicity variation, enabling a new design of directly measurable, spectrometer-free optical rulers for rapid, ultrasensitive label-free detection of various biomolecules, including streptavidin and prostate-specific antigen, down to the femtomolar level.

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