Near-infrared photothermal Candida antarctica lipase B /CuS/Cu-tetrakis (4-carboxyphenyl) porphyrin bioconjugate for remote real-time and precise control of lipase catalytic activity of glycerol esterification

To address enzyme inactivation upon immobilization and the underutilization of surplus glycerol from biodiesel production, a near-infrared (NIR)-responsive bioconjugate was developed which comprised Candida antarctica lipase B (CALB) immobilized on a CuS/Cu-TCPP support. In this design, Cu-TCPP (a porphyrin-based metal-organic framework) provides a high-surface-area scaffold, CuS nanoparticles act as NIR photothermal converters, and hydrophobic surface modification enhances lipase adsorption. XRD, XPS, SEM, and TEM confirmed the formation of covellite-structure CuS on Cu-TCPP and successful enzyme immobilization. The system achieves a photothermal conversion efficiency of 22.70% (defined as the ratio of heat generated to absorbed laser energy), retains 99.52% of its initial activity at 70 °C, and preserves 74.20% activity after five reuse cycles. During glycerol esterification under NIR irradiation (808 nm) at room temperature, oleic acid conversion reaches 69.2%, representing a 2.42-fold increase compared to the non-irradiated control (28.6%). Bandgap analysis (1.66 eV > 1.53 eV) confirms the absence of reactive oxygen species generation, preventing enzyme oxidative inactivation. This work enables remote, real-time, and precise control of lipase catalysis via localized photothermal heating, offering a green strategy for glycerol valorization.