In the present study, we constructed an ultrasensitive solid surface fluorescence-immunosensor based on highly luminescent CdTe@CdS-PAMAM structures as nanoprobe for determination of HBsAg by monitoring fluorescence intensity. This strategy was achieved by using PAMAM as a signal amplifier; the PAMAM dendrimer with the many functional amine groups can amplify the fluorescence signal of QDs by covalent attachment of CdTe@CdS on PAMAM and hence, improve the sensitivity of the proposed method significantly. A sandwich type immunosensor was formed after the addition of HBsAg and the PAMAM-QD-Ab2, respectively. Under optimal conditions, the designed immunosensor demonstrates a good analytical performance for the HBsAg detection in an excellent linear range from 5 fg ml−1 to 0.15 ng ml−1 with the detection limit (LOD) of 0.6 fg ml−1 at a S/N ratio of 3. In addition, the analysis of human serum samples shows that the fluorescent immunoassay has the great potential for early diagnosis of hepatitis B and can be used for the detection of other tumor markers in clinical applications.
