Figure 4.

Colorimetric detection of AFP in human serum by the MeLISA. A double-blind experiment was performed for the detection of AFP in serum from clinical patients. a, Photograph for the AFP detection in 96 unrelated real samples using the MeLISA. Negative samples yielded red solution with dispersed AuNPs, whereas positive ones yielded blue or purple solution with aggregated AuNPs. 5 false-negative samples were marked with white circle. b, Vertical scatter plots of the values of A_{620 nm}/A_{520 nm} for positive and negative samples (each serum sample is represented by one solid circle for AFP detection). c, Receiver operating characteristic (ROC) curve was employed to illustrate the sensitivity and specificity of the MeLISA for AFP in clinical samples.