A Novel Approach to Label-Free Biosensors Based on Photonic Bandgap Structures

Author(s):  
JAVIER GARCÍA CASTELLÓ
2019 ◽  
Vol 10 ◽  
pp. 967-974
Author(s):  
Jad Sabek ◽  
Francisco Javier Díaz-Fernández ◽  
Luis Torrijos-Morán ◽  
Zeneida Díaz-Betancor ◽  
Ángel Maquieira ◽  
...  

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.


Biomedicines ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 755
Author(s):  
Rima Budvytyte ◽  
Akvile Milasiute ◽  
Dalius Vitkus ◽  
Kestutis Strupas ◽  
Aiste Gulla ◽  
...  

Extracellular heat shock proteins (HSPs) mediate immunological functions and are involved in pathologies such as infection, stress, and cancer. Here, we demonstrated the dependence of an amount of HSP70 and HSP90 in serum vs. severity of acute pancreatitis (AP) on a cohort of 49 patients. Tethered bilayer lipid membranes (tBLMs) have been developed to investigate HSPs’ interactions with tBLMs that can be probed by electrochemical impedance spectroscopy (EIS). The results revealed that HSP70 and HSP90 interact via different mechanisms. HSP70 shows the damage of the membrane, while HSP90 increases the insulation properties of tBLM. These findings provide evidence that EIS offers a novel approach for the study of the changes in membrane integrity induced by HSPs proteins. Herein, we present an alternative electrochemical technique, without any immunoprobes, that allows for the monitoring of HSPs on nanoscaled tBLM arrangement in biologics samples such us human urine. This study demonstrates the great potential of tBLM to be used as a membrane based biosensor for novel, simple, and non-invasive label-free analytical system for the prediction of AP severity.


2007 ◽  
Vol 280-283 ◽  
pp. 533-536
Author(s):  
Hai Qing Yin ◽  
Soshu Kirihara ◽  
Yoshinari Miyamoto

The three-dimensional (3D) photonic band gap material is a material that there exists a full photonic band gap in which waves are forbidden to propagate whatever the polarization or the direction of propagation. In order to obtain photonic bandgap in lower range, we focus on the fabrication of PBG materials of diamond structure with TiO2 powder mixed with SiO2. The inverse epoxy structure with periodic diamond lattices in millimeter order has been fabricated by stereolithographic rapid prototyping. TiO2 slurry was filled into the epoxy structure and then cold isostatic pressing was applied. After sintering at 700K for 5hrs, the epoxy was burnt out and the designed structure was maintained perfectly. The calculated band diagram shows that there exists an absolute photonic band gap for all wave vectors. The measurement of transmission from 10 to 20 GHz in <100> direction shows that a complete band gap is formed at about 14.7-18.5 GHz. The magnitude of the maximum attenuation is as large as 30 dB at 17 GHz.


2002 ◽  
Vol 44 (2) ◽  
pp. 324-328 ◽  
Author(s):  
Zhengwei Du ◽  
Ke Gong ◽  
J.S. Fu ◽  
Baoxin Gao ◽  
Zhenghe Feng

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