Biosensors for fertility and pregnancy in cattle : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Palmerston North, New Zealand

Abstract

This project is focused on progesterone sensing, using both surface plasmon resonance (SPR) and lateral flow immunoassay (LFIA) methods with a new progesterone (P4) sensing material to develop cost effective assays for progesterone sensing in bovine serum and milk samples. P4-PEG-OVA was synthesised, characterised and used for P4 detection. The P4-PEG-OVA sensor surface showed an improvement in surface response compared with two shorter ligand 4TP-P4-OVA and 4TPH-P4-OVA in SPR studies. An analysis method has been developed and modified for bovine serum and milk analyses. The results indicated the P4-PEG-OVA ligand allowed sensitive P4 detection in SPR sensing and allowed bovine P4 cycle profiling. The SPR analysed data was compatible with the ECLIA and ELISA independent analyses and the P4 cycle of each of the three bovine milk samples showed a very similar trend and the extraction level was also consistent. The P4-PEG-OVA ligand was used to develop a LFIA sensor strip, and the inhibition assay for bovine serum and milk analyses established. The results indicated that, after appropriate sample pre-treatment, the bovine estrous cycle profile could be detected. The LFIA method can be a potentially quick, easy and cost effective semi-quantitative P4 analysis for serum and milk samples. A new material, polyhydroxyalkanoate (PHA) granules has been investigated for the possibility of developing a new surface biosensor. From the surface studies, the results indicated that the 3GNZZPhaC beads have the potential to become an alternative binding material for SPR sensing due to its unique gold binding property. A flow cell was designed, constructed, and tested on 3GNZZPhaC beads prior the preliminary SPR investigations. The ZZPhaC beads also showed the gold binding property and ZZPhaC beads were used for SPR studies. The results suggested a possible application for them as a new SPR binding material for antibody detection.