Electrochemical Chip Combined with Immunomagnetic Beads Enrichment for the Detection of Peach Gum Binding Medium in Ancient Wall Paintings

Abstract

The sensitive determination of peach gum in aged wall painting was developed by combining protein A magnetic bead (MB) enrichment and an electrochemical immunosensor based upon a screen-printed electrode. Peach gum antibodies were immobilized onto protein A-functionalized magnetic beads with specific recognition. The prepared immunomagnetic beads (IMBs) efficiently enriched peach gum in archaeological samples, improving the accuracy. After elution, the peach gum was detected using an enzyme-linked immunosorbent assay and an electrochemical immunosensor constructed by screen-printing a three-electrode system on polyethylene terephthalate. The carbon working electrode was modified with gold nanoparticles to improve the conductivity. A detection limit of 6.4 pg·mL−1 was obtained using the immunosensor with a linear range from 0.01 to 100 ng·mL−1. Simulated wall paintings were prepared to assess the enrichment by the IMBs and the performance of electrochemical immunosensor. Archaeological samples from the Sulamani Guphaya Temple and Shi Wushe Tomb were analyzed and the results showed that more reliable results were obtained and false negatives were avoided after enrichment and electrochemical detection. Hence, IMBs were suitable for the determination of the peach gum binding medium in archaeological samples.