6–10 Jul 2026
University of the Western Cape
Africa/Johannesburg timezone
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SPR resonance angle shifts as a function of biomarker concentration

7 Jul 2026, 15:00
20m
Lecture Hall DL1 (University of the Western Cape)

Lecture Hall DL1

University of the Western Cape

Oral Presentation Track C - Photonics Photonics

Speaker

sipho Chauke (Council for Scientific and Industrial research (CSIR))

Description

Surface plasmon resonance (SPR) is an optical phenomenon arising from the excitation of collective electron oscillations (surface plasmons) at a metal-dielectric interface, typically induced by p-polarized light under conditions of total internal reflection. The resonance condition, defined by the resonance angle (θres), is highly sensitive to variations in the local refractive index near the metal surface. Such variations are commonly associated with biomolecular binding events occurring at the sensor interface. In this study, a custom-built SPR-based biosensor platform was employed to investigate shifts in the resonance angle as a function of biomarker concentration. Unlike conventional approaches that emphasize binding kinetics and affinity analysis, the present work considers biomarker concentration primarily as an optical perturbation variable. Thiolated single-stranded DNA probes of varying concentrations were immobilized and used to capture complementary target DNA sequences. Specific and non-specific targets were introduced on gold-coated sensor chips to validate the selectivity and binding behavior associated with DNA hybridization. The results revealed a linear correlation between resonance angle shifts and increasing biomarker concentration, consistent with refractive index modulation at the sensor interface. These findings demonstrate that monitoring resonance angle shifts provides a robust and reliable optical metric for quantitative concentration detection.

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Author

sipho Chauke (Council for Scientific and Industrial research (CSIR))

Co-authors

Lebogang Thobakgale (CSIR Biophotonics Photonics Centre Council for Scientific and Industrial Research) Lungile Nomcebo Thwala (CSIR) Masixole Lugongolo (CSIR) Saturnin Ombinda-Lemboumba (CSIR) Sello Lebohang Manoto (CSIR)

Presentation materials

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