Effects Of Nitrogen-doped Carbon Dot Nanomaterials On Photosynthetic Physiology And Ecology Of Wheat Seedlings And Its Biosafety Assessment

With the rapid development of nanomaterials,the biological effects and safety evaluation of nanomaterials have become the focus of research.Especially carbon nanomaterials are widely used in biological transmission due to their low preparation cost,good light stability and low toxicity.Sensing,photocatalysis,fluorescent labeling and other fields.However,the research on the nano-biological effects of carbon nanomaterials mainly focuses on the nano-toxicity and safety of carbon nanomaterials to animals and plants.In particular,the positive nano-biological effects of carbon nanomaterials on plants and their environmental behaviors need to be further systematically studied.This is of great significance for the safe and sustainable use of carbon nanomaterials.This study takes nitrogen-doped carbon dots(N-CDs)nanomaterials as an example,taking wheat seedlings as the research object,to study the positive effects of the fluorescence characteristics of N-CDs on the photosynthetic physiology and ecology of plants,and to explore the relationship between the concentration of N-CDs nanomaterials and wheat The relationship between the photosynthetic physiological and ecological indicators of seedlings,to clarify the mechanism of N-CDs nanomaterials promoting plant photosynthesis and increase biomass,and to evaluate the nano-toxic effects of N-CDs nanomaterials on cells and animals.The research results are expected to be N-CDs nanomaterials The safe and sustainable use of the company provides a theoretical and practical basis.The main research contents are as follows:(1)Using triethylenetetraamine hexaacetic acid as a single raw material,a polymer N-CDs with good water solubility was prepared by a one-step hydrothermal method.The particle size of the N-CDs is about 3.1 nm,mainly composed of dense core and surface.Long-chain composition,this structure more effectively inhibits non-radiative transitions and avoids quenching of sub-fluorescent groups due to aggregation effects,making N-CDs have a higher quantum yield.(2)The N-CDs can absorb ultraviolet light in the range of 300 nm-365 nm,and emit fluorescence that can be absorbed by chloroplasts in the range of 334 nm-600 nm,with an absolute quantum yield of 35.91%.This study also used the fluorescent properties of the N-CDs to promote photosynthesis of wheat seedlings.The results showed that the low concentration of N-CDs can significantly promote the photosynthetic rate,photosynthetic nitrogen use efficiency,root length and leaf length of wheat seedlings and other physiological and ecological indicators(P<0.05),while the high concentration of N-CDs can significantly improve the photosynthesis of wheat seedlings.The promotion of physiological and ecological indicators is not significant(P>0.05).Further studies have shown that low concentrations of N-CDs can significantly increase the activity of Rubis CO carboxylase(P<0.05),the reduction rate of DCPIP(P<0.05),and ferricyanide in wheat seedlings.Reducibility(P<0.05)and ATP production(P<0.05).In conclusion,the N-CDs synthesized in this study can enhance the photosynthesis of wheat seedlings and increase their biomass at low concentrations.(3)In order to evaluate the biological safety of N-CDs,this study conducted a study on the toxicity of cells and animals.The results showed that,in the absence of365 nm light,N-CDs had no obvious toxicity to cells and animals.When equipped with a certain intensity of 365 nm LED irradiation,N-CDs showed obvious biological toxicity.The mechanism is that N-CDs has obvious phosphorescence emission at 520nm when excited at 365 nm.It is a phosphorescent photosensitizer.It can efficiently produce singlet oxygen(¹O₂)under a certain intensity of 365 nm excitation,leading to N-CDs are cytotoxic.The N-CDs were further injected into animals,and it was found that N-CDs had no obvious toxicity to the blood biochemical indexes and liver and kidney function indexes of the animals.In short,the N-CDs synthesized in this study are not toxic at a certain concentration,and only under a certain intensity and specific wavelength excitation can they have toxic effects on cells and animals.