1：Experimental Design and Method Selection:

The study utilized localized surface plasmon resonance (LSPR) based sensing with Au nano-urchins to detect Aβ1-42 fibrillation stages. FDTD simulations were performed to prove the localized electric field enhancement in Au nano-urchins compared to Au nano-spheres.

2：Sample Selection and Data Sources:

Aβ1-42 peptide was purchased from abcam (purity>95%). Samples were prepared by mixing Aβ1-42 solution with Au nano-urchins and diluted in phosphate buffer saline (PBS).

3：List of Experimental Equipment and Materials:

Au nano-urchins of diameter 100 nm (3.84 x 10^9 particles/ml, in 0.1 mM PBS) were purchased from Sigma Aldrich. A stabilized broadband light source (360 nm to 2600 nm) was used as the excitation source.

4：84 x 10^9 particles/ml, in 1 mM PBS) were purchased from Sigma Aldrich. A stabilized broadband light source (360 nm to 2600 nm) was used as the excitation source. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Absorbance study of the sample was performed at various time intervals to monitor the change in absorption of Au nano-urchins in the presence of Aβ1-42. Data was recorded in every 5-minute interval for 90 minutes.

5：Data was recorded in every 5-minute interval for 90 minutes. Data Analysis Methods:

5. Data Analysis Methods: The absorbance peak intensity at 650 nm was used as the sensing parameter for the sensing of Aβ1-42 fibrillation.