Using ruthenium polypyridyl functionalized ZnO mesocrystals and gold nanoparticle dotted graphene composite for biological recognition and electrochemiluminescence biosensing

Using ruthenium polypyridyl functionalized ZnO mesocrystals as bionanolabels, a universal biological recognition and biosensing platform based on gold nanoparticle (AuNP) dotted reduced graphene oxide (rGO) composite was developed. AuNP-rGO accelerated electron transfer between the detection probe and the electrode, and increased the surface area of the working electrode to load greater amounts of the capture antibodies. The large surface area of ZnO mesocrystals was beneficial for loading a high content ruthenium polypyridyl complex, leading to an enhanced electrochemiluminescence signal. Using α-fetoprotein (AFP) as a model, a simple and sensitive sandwich-type electrochemiluminescence biosensor with tripropylamine (TPrA) as a coreactant for detection of AFP was constructed. The designed biosensor provided a good linear range from 0.04 to 500 ng mL^-1 with a low detection limit of 0.031 ng mL^-1 at a S/N of 3 for AFP determination. The proposed biological recognition and biosensing platform extended the application of ruthenium polypyridyl functionalized ZnO mesocrystals, which provided a new promising prospect.