Fluorescent Poly(vinyl alcohol) Films Containing Chlorogenic Acid Carbon Nanodots for Food Monitoring

Functional materials that can sense food quality, detect additives, and lengthen storage times have huge potential in the food industry. Such materials, however, typically require toxic raw materials and complicated syntheses. Here, chlorogenic acid was used to fabricate photoluminescent carbon dots in an environmentally friendly and economical method. Transmission electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy showed a conjugated structure containing phenolic hydroxyl moieties. The carbon dots were doped into poly(vinyl alcohol) (PVA) to produce a functional film with good physical and mechanical performances. The optical properties of the film were characterized by UV–vis and photoluminescence spectroscopy. The fluorescence of the film was found to be sensitive to both the pH and Al3+ ions. Scanning electron microscopy and atomic force microscopy micrographs showed the surface roughness of the fluorescent and PVA films. A solution of carbon dots and the functional film both demonstrated strong antioxidant capacity, and the as-prepared film showed good resistance to photobleaching. The film can be used to limit fruit shelf life, to detect Al3+ residues in food, and to sense basic substances, including amines produced during spoilage. The film is a potential promising intelligent food-packaging material that can both extend the shelf life of foods and sense additives or contaminants.