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<p>This study investigates the effect of thin gold film (TGF) thickness comparing 50&#xa0;nm (TGF<sub>50</sub>) and 100&#xa0;nm (TGF<sub>100</sub>) on the performance of a reflective surface-enhanced Fourier transform near-infrared (SE-FTNIR) and label-free surface-enhanced Raman scattering (SERS) immunosensor for detecting the HER-II breast cancer biomarker in blood serum. PCB-based TGFs were functionalized with monoclonal antibody (mAb)-conjugated gold nanourchins (GNUs) to enable specific, directional binding to HER-II antigens. Surface morphology analyzed via SEM and AFM revealed differences in nanoparticle distribution and roughness between the two film thicknesses. To optimize the enhancement factor (EF), TGF<sub>50</sub> was tested using Rhodamine 6G (R6G) at 1 µM and 10 mM. SE-FTNIR results showed that TGF<sub>50</sub> produced higher reflection intensities, stronger peak enhancements, and better spectral overlap than TG<sub>F100</sub>, especially when combined with GNUs. Both TGF<sub>50</sub> + GNU and TGF<sub>100</sub> + GNU demonstrated improved reflectivity over unmodified substrates. SERS analysis confirmed that TGF<sub>50</sub> + GNU outperformed TGF<sub>100</sub> + GNU, yielding stronger Raman signals due to superior plasmonic activity. Data processing including spectral filtering, baseline correction, and normalization was conducted using Python scripts. Additionally, increased TGF thickness was linked to changes in nanoparticle morphology, such as higher ellipticity, which impacted optical performance. Shaking the solution further enhanced EF, increasing it from 0.18 × 10⁵ at 2 mW after 16&#xa0;h (unshaken) to 0.35 × 10⁵ at 2 mW after just 10&#xa0;min (shaken). These findings underscore the importance of substrate thickness, shaking, and surface engineering in improving biosensor sensitivity for accurate HER-II biomarker detection.</p> Graphical Abstract <p></p>

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Nanoarchitectonic optimization of film thickness and immobilization time of gold nanourchins for directional, label-free immunosensing of cancer biomarkers in blood serum

  • 期刊论文

  • 发表日期：

    2025年10月24日

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  • Mohammad E. Khosroshahi,
  • Yesha Patel,
  • Christine Gaoiran

摘要

This study investigates the effect of thin gold film (TGF) thickness comparing 50 nm (TGF50) and 100 nm (TGF100) on the performance of a reflective surface-enhanced Fourier transform near-infrared (SE-FTNIR) and label-free surface-enhanced Raman scattering (SERS) immunosensor for detecting the HER-II breast cancer biomarker in blood serum. PCB-based TGFs were functionalized with monoclonal antibody (mAb)-conjugated gold nanourchins (GNUs) to enable specific, directional binding to HER-II antigens. Surface morphology analyzed via SEM and AFM revealed differences in nanoparticle distribution and roughness between the two film thicknesses. To optimize the enhancement factor (EF), TGF50 was tested using Rhodamine 6G (R6G) at 1 µM and 10 mM. SE-FTNIR results showed that TGF50 produced higher reflection intensities, stronger peak enhancements, and better spectral overlap than TGF100, especially when combined with GNUs. Both TGF50 + GNU and TGF100 + GNU demonstrated improved reflectivity over unmodified substrates. SERS analysis confirmed that TGF50 + GNU outperformed TGF100 + GNU, yielding stronger Raman signals due to superior plasmonic activity. Data processing including spectral filtering, baseline correction, and normalization was conducted using Python scripts. Additionally, increased TGF thickness was linked to changes in nanoparticle morphology, such as higher ellipticity, which impacted optical performance. Shaking the solution further enhanced EF, increasing it from 0.18 × 10⁵ at 2 mW after 16 h (unshaken) to 0.35 × 10⁵ at 2 mW after just 10 min (shaken). These findings underscore the importance of substrate thickness, shaking, and surface engineering in improving biosensor sensitivity for accurate HER-II biomarker detection.

Graphical Abstract