Ultrasensitive nanostructured immunosensor for stem and carcinoma cell pluripotency gatekeeper protein NANOG

Aims: To develop an immunosensor for ultrasensitive detection of the NANOG protein. NANOG regulates pluripotency in stem cells and some cancer cells. This article reports the first electrochemical immunosensor for ultrasensitive detection and absolute quantification of the NANOG protein. The sensor features dense capture antibody-coated gold nanoparticle layers on a pyrolytic graphite underlayer. Materials & methods: Two separate multilabel detection strategies were used to achieve moderate and ultra-high sensitivity. Results: Good sensitivity was achieved for NANOG over the concentration range 0.1-160 pg/ml. The moderate-sensitivity approach gave a detection limit of 25 pg/ml, while the ultrasensitive method achieved a 250-fold lower detection limit of 0.1 pg/ml. Amounts of NANOG detected in human embryonic stem cell lysates correlated well with qualitative western blots and mRNA expression. Conclusion: The electrochemical gold nanoparticle immunosensor is suitable for measuring NANOG protein expression in stem and carcinoma cell tissue lysates at very low levels. Original submitted 29 September 2011; Revised submitted 15 November 2011; Published online 6 March 201.