An electrochemiluminescence strategy based on aptamers and nanoparticles for the detection of cancer cells

A PCR (polymerase chain reaction)-free electrochemiluminescence (ECL) strategy based on aptamers and ECL nanoprobes was developed for rapid collection and detection of Ramos cells. The ECL nanoprobes consisted of gold nanoparticles (AuNPs), linker DNA and tris-(2,2′-bipyridyl) ruthenium (TBR)-labeled signal DNA. The linker DNA and signal DNA were modified on the surface of the AuNPs through AuS bonds. The linker DNA can hybridize partly with the aptamers loaded on the magnetic beads to construct the magnetic biocomplex. In the presence of the cancer cells, the aptamers conjugated with the cancer cells with higher affinity. The ECL nanoprobe released from the biocomplex and subsequently hybridized with the capture DNA modified on the Au electrode. The ECL intensity of the TBR loaded on the nanoprobes directly reflected the amount of the cancer cells. With the use of the developed ECL probe, a limit of detection as low as 50 Ramos cells per mL could be achieved. The proposed methods based on ECL should have wide applications in the diagnosis of cancers due to their high sensitivity, simplicity and low cost.