Platinum nanoparticles-loaded cherry radish polysaccharides with high oxidase-like activity for rapid colorimetric analysis of ascorbic acid.

Ascorbic acid (AA) is an indispensable trace component in the human body. The main supplement source is fruits, vegetables and supplements. Therefore, it is necessary to detect AA content in food. Cherry radish polysaccharides (CRRP) with regular network-like structures and tentacles, extracted from cherry radish by a simple extraction method, possess water solubility and antioxidant ability due to their abundant hydroxyl and aldehyde groups. Herein, CRRP-loaded platinum nanoparticles (CRRP-Ptn NPs) were prepared by a facile method to address the prone to aggregation of platinum nanoparticles. CRRP-Pt50 NPs displayed enhanced stability and good oxidase-like activity. A colorimetric detection method for AA in fruits and supplements was established based on the oxidase-like activity of CRRP-Pt50 NPs. Furthermore, a convenient smartphone-assisted AA colorimetric detection platform was established based on the RGB mode analysis of smartphones. The linear range and the limit of detection of AA was 0-300 μM and 0.69 μM. The established method was successfully used in the detection of AA in real examples, which is promising to realize the rapid analysis of AA.