Sensitivity enhancement with anti-reflection coating of silicon nitride (Si 3 N 4 ) layer in silver-based Surface Plasmo
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Sensitivity enhancement with anti‑reflection coating of silicon nitride (Si3N4) layer in silver‑based Surface Plasmon Resonance (SPR) sensor for sensing of DNA hybridization N. Mudgal1 · Ankur Saharia1 · Kamal Kishor Choure1 · Ankit Agarwal1 · G. Singh1 Received: 9 July 2020 / Accepted: 3 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This work presents a highly sensitive silver (Ag) based Surface Plasmon Resonance (SPR) sensor with graphene-coated over Silicon nitride (Si3N4) for sensing of Deoxyribonucleic acid (DNA) hybridization. The design consists of five layers namely Ag, Si3N4, graphene, and sensing medium along with BK7 glass prism that couple light at the metal–dielectric interface. The performance of the present structure has been evaluated using the angular interrogation method. The present investigation reveals the difference in complementary DNA strands and mismatched DNA strands as well as single-nucleotide polymorphisms (SNP) event by examining the variation of resonance angle in the reflectivity spectrum. The performance of the present structure is compared with the contemporary structures and found better than existing sensors. Therefore, the proposed structure is suitable in the biochemical field for the detection of biomolecules interactions. Keywords Surface Plasmon Resonance · Sensitivity · Silicon nitride · DNA · Biosensor
1 Introduction In present days, SPR technology has emerged as leading sensing technology in the biochemical field in the analysis of various substances like DNA, protein binding, and different enzymes, etc. [1–4]. DNA hybridization is an exercise of combining two single-stranded DNA (ssDNA) and this results in the formation of double-stranded DNA (dsDNA). Combining two ssDNA is performed by the hydrogen bonds formed between the nucleotide bases. DNA hybridization measures the genetic similarity between two pools of the DNA sequence which can be used to diagnose more than 400 diseases directly. The dsDNA hybridization event and the mismatched DNA hybridization event are illustrated in Fig. 1a, b, respectively. In DNA hybridization, probe ssDNA is used to identify unknown, target ssDNA that results in DNA hybridization event by generating dsDNA as shown in Fig. 1a.
* N. Mudgal [email protected] 1
Department of ECE, Malaviya National Institute of Technology, Rajasthan, India
The hybridization process is a bio-recognition process of identifying nucleotide-binding between the base pairs, i.e., guanine (G) and cytosine (C), adenine (A), and thymine (T) [5, 6]. Surface plasmons (SPs) are the collective free electrons oscillation at the interface between metal and dielectric and are excited using the p-polarized light beam at the interface. This results in the generation of the evanescent wave at the interface that decays exponentially. This collective phenomenon is known as SPR. SPR sensing is the labelfree sensing that works on the principle of the shift of the resonance angle when there is a variation in the refractive index
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