Abstract: Nanozymes capped with a radical-scavenging capping agent are disclosed for use in biosensing assays with improved sensitivity. The radical-scavenging capping agent facilitates the capture and retention of one or more radicals for enhancing a catalytic reaction. In some example embodiments, the nanozyme capped by the radical-scavenging capping agent is capable of catalyzing the decomposition of hydrogen peroxide or molecular oxygen. The capped nanozymes may be incorporated with an electrode, such as the working electrode of an electrochemical sensor, for achieving enhanced catalytic activity and a lower limit of detection. In some example embodiments, the radical-scavenging capping agent is or includes thiocyanate.