Fluorescent Carbon Dots From Roasted Lamb:Their Formation Mechanism And Potential Application

Food-borne nanoparticles receive extensive concern owing to their unique physical and chemical prosperities.In addition to the nanoparticles add to food as the food additive,nanostructures may also formed due to the complex interaction among food components during the food processing.However,almost all studies regarding nanoparticles in food has focus on exogenous added nanoparticles,the endogenous nanoparticles formed during food processing are seldom awarded.In this study,the formation process of endogenous nanoparticles and their potential application were investigated by using lamb as an example.First,the formation process of nanoparticles in baked lambs was examined.Morphology,elemental composition,surface groups,and fluorescence properties of fluorescent nanoparticles obtained at 200,250,300,and 350^oC were characterized.The results showed that the particle size of nanoparticles decreased with the increment of baking temperature,while the fluorescence quantum yield increased.A raise in the content of carbon element,C=O and C-N in the nanoparticles were also observed with the increment of baking temperature.It is shown that the formation process of nanoparticle in baked lamb is gradually carbonized by protein and lipid compounds under high temperature condition,and the surface groups gradually oxidize.Secondly,the antioxidant activity of nanoparticles was investigated.The electron spin-resonance spectroscopy was used to exam the free radicals scavenging activity of nanoparticles from baked lamb.The results showed that could quench hydroxyl and DPPH radicals.Importantly,their scavenging activity was baking temperature dependent which reached the maximum value at 350^oC.Furthermore,the protection of nanoparticles on cell oxidative damage was demonstrated by using HepG2 cells as a model.The nanoparticles containing medium protect cell from oxidative.This result verified the in vitro antioxidant abilities of nanoparticles from baked lamb.Finally,a fluorescent nano-sensor for glucose detection was constructed.Glucose oxidase can specifically interact with glucose and produce hydrogen peroxide.Hydrogen peroxide produces hydroxyl radicals in the presence of ferrous particles.Hydroxyl radicals can quench their fluorescence by oxidizing the surface groups of CDs.The quenching degree is positively correlated with the glucose content.Based on this principle,optimized the condition of glucose detection,the study showed that the fluorescence quenching efficiency and the concentration of glucose exhibited a good linear relationship in the range of 10 to 300?mol·L^-1 and the detection limit was as low as 2.9?mol·L^-1.In order to detect the anti-interference ability of fluorescence nanoparticle sensor,the fluorescence quenching degree of nanoparticles with the same concentration of D-fructose,?-lactose,sucrose and other sugars and glucose solution was tested and the results showed that the nanoparticle solution containing interfering sugar had fluorescence.The quenching degree is less than 0.1,indicating that the fluorescence sensor has anti-interference ability.In addition,the results of content of glucose in the actual sample were similar,measured by ion chromatography and nanoparticles.The properties,formation mechanism and potential applications of fluorescent nanoparticles in baked lamb were investigated.Those result provided a basis for in-depth understanding of the properties of endogenous nanoparticles that formed during food processing.