Construction Of Novel Nanoprobe And Its Application In Vitamin C Detection

Ascorbic acid?AA?,commonly referred to as vitamin C,is a vitamin essential for the body.Vitamin C plays an irreplaceable role in many processes in human daily life.At the same time,vitamin C is widely used in many fields.However,as an exogenous chemical,vitamin C cannot be synthesized in the human body and can only be taken from food to maintain the necessary content of the human body.Therefore,the development of effective vitamin C sensing strategy is undoubtedly important for disease diagnosis and food safety in daily life.Firstly,fluorescent nanoparticles with high fluorescence performance were prepared by hydrothermal synthesis using citric acid and glycine as raw materials;potassium permanganate,cetyltrimethyl bromide,morphine ethanesulfonic acid,and hydroxide Sodium is used as a raw material to prepare stable MnO₂ nanosheets.The fluorescence properties,morphology,elemental composition and surface groups of fluorescent nanoparticles and MnO₂ nanosheets were characterized.The results show that the MnO₂ nanosheets have strong absorption in the range of 200 nm-500 nm,and overlap with the excitation and emission wavelengths of the fluorescent nanoparticles.The fluorescence of the fluorescent nanoparticles can be quenched by the internal filtration effect.Secondly,a fluorescent/nuclear magnetic double response-based probe was constructed for the detection of vitamin C.The fluorescence of the fluorescent nanoparticles can be quenched because the absorption peak range of the MnO₂nanosheet overlaps with the excitation and emission wavelengths of the fluorescent nanoparticles.When the reducing vitamin C was added to the system,the MnO₂nanosheets were reduced to metal manganese ions Mn²⁺,and the strong absorption of MnO₂ nanosheets at 200 nm-500 nm disappeared,and the fluorescence of the fluorescent nanoparticles was restored.At the same time,the metal manganese ion Mn²⁺interacts with water,which can significantly change the transverse relaxation time T₂and the longitudinal relaxation time T₁ of hydrogen protons in water.This change can be conveniently detected by low field nuclear magnetic.Based on this principle,the detection conditions of vitamin C were optimized.It was found that the degree of fluorescence recovery showed a good linear relationship with the content of vitamin C in the range of 5-80?M.The minimum detection limit was 2.89?M.The transverse relaxation time T₂ and the longitudinal relaxation time T₁ and vitamin C content showed a good linear relationship in the range of 20-80?M.The minimum detection limits were0.776?M and 4.32?M,respectively.Finally,the anti-interference ability of the dual-response probe was investigated.In addition to vitamin C,the addition of different metal ions,sugars,amino acids,etc.to the probe system did not significantly affect the fluorescence intensity and nuclear magnetic signal of the probe system.The change indicates that the dual-function probe has a certain anti-interference ability.The probe was used to detect the vitamin C in the actual beverage samples,and the results were more accurate.In addition,the nuclear magnetic T₁-weighted imaging performance of the probe on the vitamin C distribution in mice was evaluated.The results showed that the contrast of the nuclear magnetic T₁-weighted image of the stomach region of the mice carrying the probe in vivo was significantly enhanced?brightening?.This result indicates that the bifunctional probe can be used as a potential contrast agent for vitamin C nuclear magnetic imaging in vivo.This study constructs a new probe for fluorescence/nuclear magnetic double response for the detection of vitamin C,which provides a basis for innovation in detection methods in food or other fields.