1：Experimental Design and Method Selection:

The study involved the preparation of N-doped carbon dots (N-CDs) by microwave procedure using glucose and ammonium sulfite, and their application in catalyzing the reduction of AgNO3 by trisodium citrate (TCA) to form nanosilver (AgNP). The formed AgNPs were used as indicators in the presence of Vitoria blue B (VBB) molecule probe for SERS detection.

2：Sample Selection and Data Sources:

The samples included milk purchased from supermarkets, which were prepared by ultrasonic wave irradiation and filtration.

3：List of Experimental Equipment and Materials:

Instruments included a DXR smart Raman spectrometer, TU-1901 double beam UV–visible spectrophotometer, HH-S2 electric hot water bath, S-4800 field emission scanning electron microscope, Zeta sizer Nano particle size and zeta potential analyzer, SYZ-550 quartz sub-boiling distiller, and WX-6000 microwave digestion instrument. Reagents included VBB, ammonium sulfate, ammonium sulfite, trisodium citrate, AgNO3, glucose, biotin (Vitamin H), and avidin (Ad).

4：Experimental Procedures and Operational Workflow:

The N-CDs were prepared by microwave irradiation, and the SERS detection procedure involved mixing N-CDs reagent solution with VH, AgNO3 working solution, heating, and then adding VBB probe solution for SERS spectra recording.

5：Data Analysis Methods:

The SERS peak intensity at 1615 cm?1 was measured, and the value of ΔI = I ? I0 was calculated for quantitative analysis.