Electrochemiluminescence Biosensor for Hyaluronidase Based on the Adjustable Electrostatic Interaction between the Surface-Charge-Controllable Nanoparticles and Negatively Charged Electrode

A novel electrochemiluminescence (ECL) biosensor for hyaluronidase (HAase) based on the adjustable electrostatic interaction between the surface-charge-controllable nanoparticles and negatively charged electrode has been devised. Hyaluronic acid (HA)-coated amino-modified ruthenium bipyridine-doped silica nanoparticles (Ru@SiO2–NH2@HA NPs) have been synthesized and act as ECL indicators, and the surface of this particle is negatively charged because HA contains a large amount of OH– and COO–. The strong electrostatic repulsion between the Ru@SiO2–NH2@HA NPs and negatively charged indium tin oxide (ITO) electrode surface leads to the detection of a low-intensity ECL signal. In the presence of HAase, the HA on the surface of the Ru@SiO2–NH2@HA NPs can be decomposed, and the particles can be transformed into positively charged amino-modified ruthenium bipyridine-doped silica nanoparticles (Ru@SiO2–NH2 NPs), which can be concentrated near the surface of the ITO electrode through electrostatic attraction, and result in the detection of an enhanced ECL signal. The ECL of the system has a good linear relationship with HAase concentration in the range of 2.0–60 U/mL, and the limit of detection was 0.37 U/mL. The designed biosensor had been applied to detect the target in real samples with satisfied results.