Isothermal Titration Calorimetry for the Screening of Aflatoxin B1 Surface-Enhanced Raman Scattering Sensor Affinity Agents

In this work, isothermal titration calorimetry (ITC) is employed as an affinity agent screening method for the surface-enhanced Raman scattering (SERS) detection of aflatoxin B1 (AFB1). AFB1, a potent carcinogen produced by a fungus that infects crops, is an important target due to the monitoring required based on its FDA regulation. Polymer affinity agents, like those studied here, have the potential to enable separation and detection of relevant small molecules such as pesticides, drugs, and biological toxins, like AFB1, especially when paired with a vibrational spectroscopy technique such as SERS. Herein, seven homopolymers were synthesized to be evaluated as AFB1 affinity agents based on hypothetical hydrogen bonding interactions. Nitrogen-inclusive poly(N-(2-aminoethyl) methacrylamide) (pAEMA) polymers and their oxygen analogs, poly(2-hydroxyethyl methacrylate) (pHEMA) were evaluated. ITC was demonstrated as an effective method for rapid screening among the polymer affinity agents. Chain lengths between seven and 39 repeat units were synthesized to study length-based variance in affinity agent performance. An ITC method was optimized and used for the rapid screening of polymer affinity agents. The results were compared to those generated by SERS. Good agreement between the ITC results and follow-up SERS sensing experiments showcased ITC's screening potential for analytical applications such as separation and detection.