Circular DNA template (2 μL) and MBs-cDNA (4 μL) were mixed with 1 μL recombinant albumin, 1 μL phi29 DNA polymerase (10 U/μL), 4 μL dNTPs (10 mM), 3 μL 10 × phi29 DNA polymerase buffer and 15 μL H2O. The mixture was gently stirred and incubated at 30 °C. In the fluorometric assay, the RCA continued for 2 h before the mixture was heated at 65 °C for 10 min to inactivate the enzyme. In the colorimetric assay, 5 μL HRP solution (1 mg/mL) was added before the RCA was started and continued for 20 h. The last step of enzyme inactivation was omitted in the colorimetric assay.