Simple adsorption-based immobilization of l-asparaginase on boron-doped diamond film

• Successful immobilization of ASNase on boron-doped diamond (BDD) surfaces was achieved. • Functionalized surfaces boost ASNase immobilization yields to 68% vs. 17% untreated. • Amine-terminated BDD surfaces retain 54% enzyme activity after 3 cycles. L-asparaginase is an enzyme with diverse and significant applications, such as reducing acrylamide formation in starchy food processing and as a biopharmaceutical for treating acute lymphoblastic leukaemia. However, the free enzyme is susceptible to external factors, leading to reduced stability compared to its immobilized forms. L-asparaginase was adsorbed onto both amine- and oxygen-terminated boron-doped diamond surfaces under controlled conditions (pH 8, 37 °C, 0.06 mg/mL ASNase, and 1 h immobilization on 5 × 5 mm boron-doped diamond surfaces). Boron-doped diamond surfaces were grown from hot-filament chemical vapor deposition. The results show a successful enzyme immobilization, with the amine- and oxygen-terminated surfaces exhibiting an enhanced immobilization yield of up to 68%, compared to just 17% on untreated as-grown boron-doped diamond. Notably, amine-terminated boron-doped diamond surface maintained 54% of its initial relative activity after three cycles of reaction, outperforming other diamond surfaces. This work demonstrates the potential of boron-doped diamond surfaces for immobilizing and reuse of L-asparaginase through simple adsorption, which could be valuable for future biosensing applications.