Inhibition of Polyphenol Oxidase Activity by Mesoporous Silica Nanoparticles and Multiwalled Carbon Nanotubes Modified with Surfactants

Polyphenol oxidase (PPO) is the culprit behind the browning of fruits and vegetables. Therefore, how to reduce the thermal deactivation temperature of PPO or use as few safe reagents as possible to inhibit enzymatic browning has practical significance. Mesoporous silica nanoparticles (MSNs) and multiwalled carbon nanotubes (MWCNTs) are stable and have high biosafety. In the present study, efficient PPO inhibitors were developed based on MSNs and MWCNTs. It is found that after modification with a very small amount of dodecyl trimethylammonium bromide (DTAB, ≥60 μg/mL), MSNs can significantly inhibit the activity of PPO although single MSNs and single DTAB show very limited effect on PPO activity. After modification with a very small amount of sodium dodecyl sulfate (SDS, 5.7–9.5 μg/mL), MWCNTs almost completely inactivate PPO. However, SDS@MSN and DTAB@MWCNT cannot decrease PPO activity significantly.