A novel phosphatidylserine-functionalized AuNP for the visual detection of free copper ions with high sensitivity and...

In this paper, we have reported on novel phosphatidylserine-functionalized AuNPs (gold nanoparticles) for the visual detection of Cu²⁺ by employing phosphatidylserine for Cu²⁺ recognition and AuNPs for signal generation. The phosphatidylserine (1,2-dioleoyl-sn-glycero-3-phospho-l-serine, DOPS) was covalently assembled on the AuNP surface to obtain DOPS-functionalized AuNPs. It was demonstrated that DOPS-functionalized AuNPs could specifically bind Cu²⁺ and lead to the aggregation of AuNPs, which gave rise to a colour change from wine-red to blue and a new absorption band around 650 nm. This provides a sensing platform for the simple, rapid and field portable colorimetric detection of Cu²⁺. By using the sensing platform, a selective and sensitive visual biosensor for the detection of Cu²⁺ was developed. The proposed biosensor has outstanding analytical advantages such as good stability, relatively high sensitivity, low cost and short analysis time. It can be used to detect concentrations of Cu²⁺ as low as 30 μM in river water by observation with the naked eye and of 1.55 μM Cu²⁺ in river water by UV-visible spectrophotometry, within 10 min and with a recovery of 98-103% and a relative standard deviation (RSD) < 4% (n = 6). The proposed biosensor is promising for on-site detection of trace Cu²⁺ in clinical diagnosis or environmental monitoring.