Development and Characterization of artificial receptors for boar taint by means of molecular imprinting

Boar taint is an off-odour resulting from the accumulation of androstenone (AEON), skatole (SK), and indole (IND) in adipose tissue of intact male porcines [1]. Since boar taint causes negative consumer reactions, it is crucial to prevent tainted pig carcasses to reach consumers. To this end, rapid screening methods are required in which molecularly imprinted polymers (MIPs) can serve as artificial recognition elements. In this study, different MIPs for AEON and SK were synthesized through precipitation polymerization. Afterwards, all MIPs were characterized by batch rebinding studies through binding isotherms and scatchard analysis. Synthesis of MIPs was executed using 3 functional monomers, 3 cross-linkers, 3 porogen solvents, and 2 initiators. The polymerization reaction was initiated thermally or by UV-radiation and the reaction time varied from 8 to 48 hours. Most of the MIPs showed a low specificity with mean imprinting factors (IF) ranging from 1.10 to 1.99 and 1.13 to 1.69 for AEON and SK, respectively. This low affinity could also be derived from the dissociation constants (Kd) and maximum binding sites (Bmax) of the MIPs with Kd values ranging from 48 to 319 µmol l-1 and 38 to 547 µmol l-1 and Bmax values ranging from 3.38 to 20.89 µmol g-1 and 1.59 to 10.89 µmol g-1 for AEON and SK, respectively. Despite the low specificity due to low functionality and small size of the templates, for SK two MIPs with a higher specificity could be synthesized with IF values of 2.64 and 5.61 for MIP S1 and MIP S9, respectively. MIP S1 was associated with a Bmax value of 2.73 µmol g-1 and Kd of 30 µmol l-1. MIP S9 presented a Bmax of 2.27 µmol g-1 and Kd of 15 µmol l-1. For AEON, a slightly higher specificity and affinity were observed for MIP A6, which was associated with an IF of 1.99, Kd of 1.85 µmol l-1 and Bmax of 23 µmol g-1. Because of the small size and limited functionality of SK and AEON, most MIPs presented too low specificity and affinity, which compromises their ability to serve as highly specific recognition elements in sensor technology. For this reason, future perspectives include increasing specificity and selectivity by applying a fingerprinting approach and controlling the imprinting process by surface grafting or colloidal crystal templating.

Publication year:2015