Protein-Supported RuO₂ Nanoparticles with Improved Catalytic Activity, In Vitro Salt Resistance, and Biocompatibility: Colorimetric and Electrochemical Biosensing of Cellular H₂O₂

Protein-supported nanoparticles have a great significance in scientific and nanotechnology research because of their “green” process, low cost-in-use, good biocompatibility, and some interesting properties. Ruthenium oxide nanoparticles (RuO 2 NPs) have been considered to be an important member in nanotechnology research. However, the biosynthetic approach of RuO 2 NPs is relatively few compared to those of other nanoparticles. To address this challenge, this work presented a new way for RuO 2 NP synthesis (BSA-RuO 2 NPs) supported by bovine serum albumin (BSA). BSA-RuO 2 NPs are confirmed to exert peroxidase-like activity, electrocatalytic activity, in vitro salt resistance (2 M NaCl), and biocompatibility. Results indicate that BSA-RuO 2 NPs have higher affinity binding for 3,3′,5,5′-tetramethylbenzidine or H 2 O 2 than bare RuO 2 NPs. Moreover, BSA turns out to be a crucial factor in promoting the stability of RuO 2 NPs. Taking the advantages of these improved properties, we established colorimetric (linear range from 2 to 800 μM, a limit of detection of 1.8 μM) and electrochemical (linear range from 0.4 to 3850 μM, a limit of detection of 0.18 μM) biosensors for monitoring in situ H 2 O 2 secretion from living MCF-7 cells. Herein, this work offers a new biosynthesis strategy to obtain BSA-RuO 2 NPs and sheds light on the sensitive biosensors to monitor the H 2 O 2 secreted from living cells for promising applications in the fields of nanotechnology, biology, biosensors, and medicine.