A New Phosphorimetry for the Determination of Trace Alkaline Phosphatase Using Multi-wall Carbon Nanotubes and Its Diagnosis of Human Diseases

Multi-wall carbon nanotubes (MWNTs) could be modified as water soluble MWNTs (it was called as MWNTs-A and MWNTs-B) by chemical methods. MWNTs-A and MWNTs-B could emit room temperature phosphorescence (RTP) signal on the surface of nitrocellulose membrane (NCM). A new solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace alkaline phosphatase (ALP) was established based on the signal magnification effect of tween-80 and ALP on MWNTs-B’s RTP intensity and the linear relationship between the content of ALP and the ΔI P of the system. The linear range of this method was 0.0020–0.80 (fg spot−1, sample volume: 0.40 μl spot−1), the regression equation of working curve was \( \Delta {I_P} = 0.8170 + 96.84{m_{ALP}}\left( {fg{ }spo{t^{ - 1}}} \right) \), correlation coefficient (r) was 0.9986. This method had high sensitivity (detection limit (LD): 1.4 ag spot−1), good selectivity (Er ≤ ± 5℅, coexistence species were of no interference), high precision (RSDs were 4.4%-1.2%) and accuracy. It was applied to the determination of trace ALP in human serum and the diagnosis of human diseases. The results were tallied with those of enzyme-linked immunosorbent assay (ELISA). The mechanism of new SS-RTP for the determination of trace ALP was discussed, which laid the theory foundation for the analytical application of MWNTs in life science.