More accurate and more efficient: Penicillinase-immobilized phase-change microcapsules for detection and removal of penicillins under microenvironmental thermal management

Aiming at a high thermal sensitivity of penicillinase (Pen X) in the enzyme-catalyzed hydrolytic reaction of penicillins, we developed a novel type of Pen X-immobilized phase-change microcapsules with a thermo-temperature regulation function for enhancing the detection accuracy and removal efficiency of penicillins under high temperature environments. The microcapsules were constructed by microencapsulating n-docosane in a SiO2 shell, followed by decorating a biocompatible chitosan coating layer on the shell surface and then immobilizing Pen X through covalent bonding. The resultant Pen X-immobilized microcapsules exhibit a well-defined core-shell microstructure and a regular spherical morphology, together with the desired chemical compositions and structures. The microcapsules present a high heat storage capacity of over 125 J/g to regulate their microenvironmental temperature through reversible phase transitions by their n-docosane core. This enables the Pen X-immobilized microcapsules to achieve a higher enzyme activity at high assay temperatures compared to conventional immobilized Pen X, resulting in a high removal rate of 94.71 % for Pen G elimination and an extremely high recovery rate of nearly 100 % for Pen G determination. Based on their superior biocatalytic capability at high temperatures, the Pen X-immobilized microcapsules developed in this study exhibit great application potential for high-accurate detection and high-efficient removal of penicillins in harsh conditions.