1：Experimental Design and Method Selection:

The study uses a FRET-based aptasensor design where AFP aptamer-labeled CdTe quantum dots (donor) and anti-AFP antibody-functionalized gold nanoparticles (acceptor) are brought close by AFP binding, leading to fluorescence quenching. The method involves synthesis of functionalized nanoparticles and fluorescence measurements.

2：Sample Selection and Data Sources:

Human serum samples from healthy adults were used after filtration and dilution. AFP standards were prepared in various concentrations for calibration.

3：List of Experimental Equipment and Materials:

Includes chemicals like HAuCl4·3H2O, MPA, EDC, NHS, APTS, NHS-PEG-S-S-PEG-NHS, mPEG-SH, BSA, PBS, AFP, anti-AFP antibody, and others from suppliers such as Abcam, Sigma-Aldrich, Sangon Biotechnology, and Sinopharm Chemical Reagent. Equipment includes a Hitachi F-4600 fluorescence spectrophotometer and TEM for characterization.

4：Experimental Procedures and Operational Workflow:

Synthesis of 13 nm AuNPs via citrate reduction, conjugation with AFP antibody using PEG linkers. Synthesis of CdTe QDs with varying reaction times, coating on SiO2 nanoparticles, and functionalization with AFP aptamer. Fluorescence measurements were performed after incubating apt-QD-SNPs with AFP and Ab-AuNPs, with excitation at 485 nm and emission from 500-650 nm.

5：Data Analysis Methods:

Fluorescence intensity was measured, and energy transfer efficiency (E=1-F'/F0) was calculated. Linear calibration curves were plotted, and detection limits were determined based on signal-to-noise ratio. Specificity was tested against other proteins, and recovery studies were conducted in serum samples.