Smartphone-assisted detection platform with dendritic-like N-doped meso-macroporous carbon nanozyme for fast and colorimetric detection of D-limonene

D-limonene is one of the most decisive quality markers for many fruits and agricultural crops. The determination of D-limonene is critical for precision and postharvest agricultures. Therefore, a simple, low-cost and effective nanozyme-based strategy was firstly proposed for fast and colorimetric detection of D-limonene. A dendritic-like N-doped carbon nanozyme (DNCzyme) with hierarchically meso-macroporous structure was synthesized, which can oxidize H2O2 to generate hydroxyl radicals and subsequently exhibit peroxidase (POD)-like activity in 3,3 ',5,5 '-tetramethylbenzidine solution. Coincidentally, D-limonene can scavenge hydroxyl radicals and then quench the POD-like activity. Therefore, DNCzyme was applied as a colourimetric sensor for D-limonene detection based on the "on-off" model of POD-like activity. A broad linear range from 0.05 to 18.00 mu M (R2 = 0.9923) and high sensitivity (LOD = 0.049 mu M) was obtained. Meanwhile, a smartphone-assisted DNCzyme detection platform was developed to convert D-limonene induced color changes into RGB values, and realized rapid, portable, and visual detection of D-limonene. The LOD of 0.063 mu M was achieved with a wide linear relation (2.00-16.00 mu M) for the smartphone-assisted DNCzyme platform. The DNCzyme-based methods were successfully used to detect D-limonene content in real samples, and which were verified by GC-MS method. Our findings are expected to pioneer new protocols for the design of satisfied-performance carbon-based nanozymes, and providing new perspectives for monitoring the quality change of the postharvest fruits and agricultures containing D-limonene.