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Abstract
Long-term stability of the labeled proteins is essential for clinical applications as they can determine the accuracy of the assay and is, thus, a crucial property in product development. In this paper, we report an extensive investigation of the stability of peroxidase-labeled antibodies in solution under various storage conditions (PBS, BSA, trehalose, StabilGuard®, StabilZyme Select®, and glycerol/PBS) with the aim to develop packaged multiplexed biosensors. The kinetic and thermodynamic parameters of the deactivation process were calculated and a prediction of their stability trends based on the Arrhenius equation is made. The inactivation kinetic constants obtained in the presence of the stabilizing buffers were 10 times lower than those obtained in PBS, with a half-life of ∼2 years at 4°C, indicating an excellent resistance to the denaturation of the conjugates in this buffer. From the ratio of kinetic constants at 4°C and 37°C, the equivalence between the activities measured in real time and in the accelerated study were calculated with values of 10–12, which means that one month of storage at 37°C represents approximately one year at 4°C.
Acknowledgments
This paper is part of a Special Issue of Analytical Letters focusing on papers presented at the 10th International Symposium on Kinetics in Analytical Chemistry (KAC-10).
The authors thank the EU SmartHEALTH project (FP6-2004-IST-NMP-2-016817) for financial support and Fujirebio Diagnostics AB for providing the monoclonal antibodies. Alex Fragoso thanks the Ministerio de Ciencia e Innovacion, Spain, for a “Ramón y Cajal” Research Professorship.
Notes
1. 3 × SD of the blank solution (n = 3). Values in ng/mL (for CEA and PSA) and U/mL (por CA15-3); 2. Plate coated with anti-CEA; 3. Plate coated with anti-CA15-3; 4. Plate coated with anti-PSA.