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Quantitative analysis of the response of an electrochemical biosensor for progesterone in milk
Y F Xu1, M Velasco-Garcia, T T Mottram
1Silsoe Research Institute, Bedfordshire MK45 4HS, UK. yongfu.xu@bbsrc.ac.uk
Insights
A novel electrochemical biosensor for progesterone in cow's milk was developed. A computer model accurately predicted the sensor's hook effect, crucial for accurate progesterone detection.
Area of Science:
- Electrochemistry
- Biosensors
- Immunochemistry
Background:
- Progesterone monitoring in cow's milk is vital for reproductive health.
- Existing methods may lack sensitivity or require complex procedures.
- Development of rapid and reliable biosensors is needed.
Purpose of the Study:
- To develop an electrochemical biosensor for progesterone detection in cow's milk.
- To create and validate a computer model simulating the biosensor's operation.
- To investigate the factors influencing the biosensor's hook effect.
Main Methods:
- Fabrication of screen-printed carbon electrodes (SPCEs) with anti-progesterone monoclonal antibody (mAb).
- Competitive immunoassay utilizing alkaline-phosphatase-labelled progesterone conjugate.
- Amperometric signal measurement with p-nitrophenylphosphate substrate.
- Development and validation of a computer model for biosensor simulation.
Main Results:
- The biosensor demonstrated a hook effect in the 0-5 ng/ml progesterone range.
- The computer model successfully predicted the observed hook effect.
- Model validation indicated hook effect is influenced by binding site availability and diffusion/binding rates.
Conclusions:
- The developed electrochemical biosensor is suitable for progesterone detection in cow's milk.
- The computer model provides valuable insights into biosensor operation and hook effect phenomena.
- This work contributes to the development of accurate and reliable progesterone monitoring tools.
Abstract:
An electrochemical biosensor for progesterone in cow's milk was developed and used in a competitive immunoassay by Hart et al. (1977, Studies towards a disposable screenprinted amperometric biosensor for progesterone, Biosens. Bioelectron. 12, 1113-1121). The sensor was fabricated by depositing anti-progesterone monoclonal antibody (mAb) onto screen-printed carbon electrodes (SPCEs) which were coated with rabbit anti-sheep IgG (rIgG). This sensor was operated following the steps of competitive binding between sample and conjugate (alkaline-phosphatase-labelled progesterone) for the immobilised mAb sites and measurements of an amperometric signal in the presence of p-nitrophenylphosphate using either colorimetric assays or cyclic voltammetry. The hook effect of the progesterone biosensor was found in the concentration range of milk progesterone between 0 and 5 ng/ml when the sensor was fabricated using a loading of 25 ng rIgG per electrode of a diameter of 3 mm and a 1/50 dilution of mAb. A computer model has been developed in this study to simulate the operation of this progesterone biosensor with consideration of the fabrication processes. This paper presents the results of validating the computer model and the model has predicted the hook effect as observed in tests. The model thus reveals that the hook effect is determined by the total number of binding sites available and the rates of labelled and unlabelled progesterone diffusing towards the sensor surface and the binding rates.
