Carbon quantum dot based on cysteine and glucose as well as preparation method and application of carbon quantum dot

Abstract

The invention relates to a carbon quantum dot based on cysteine and glucose as well as a preparation method and application thereof, and belongs to the technical field of preparation of carbon quantum dots. The preparation method of the carbon quantum dots based on cysteine and glucose comprises the following steps: mixing cysteine, glucose and a solvent to obtain a reaction solution, adjusting the pH value of the reaction solution to be alkaline, and performing microwave-assisted pyrolysis to obtain the carbon quantum dots. No heavy metal element is introduced into the carbon quantum dot based on cysteine and glucose, so that the carbon quantum dot is environment-friendly. The cysteine and glucose-based carbon quantum dots can relieve salt stress of peas by enhancing antioxidant defense, protecting a photosynthetic system, optimizing osmotic regulation, regulating protein protection and repair and integrating signal transduction and metabolic regulation.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon quantum dot preparation, and in particular relates to carbon quantum dots based on cysteine ​​and glucose, and a preparation method and application thereof. Background Art

[0002] Soil salinization affects arable land in many countries and is a major factor limiting crop yields. Salt stress first inhibits seed germination, reducing seed emergence rates in the field, leading to uneven emergence and reduced yields later in life. Second, salt stress continues after seed emergence, exposing plants to osmotic, ionic, and oxidative stresses during their growth stages. Therefore, improving salt tolerance in crops during the seed and seedling stages to maintain healthy vegetative growth is crucial.

[0003] Carbon quantum dots (CQDs) are a new type of bioluminescent carbon nanomaterial. They possess excellent biocompatibility, water solubility, stable photoelectric properties, strong fluorescence, low toxicity, and ease of functionalization, attracting widespread attention from researchers. Patent application number CN118901441A discloses the use of cerium-doped CQDs in promoting lateral root formation in plants. The preparation method for these cerium-doped CQDs includes the following steps: mixing citric acid, cerium chloride, ethylenediamine, and water, performing a hydrothermal reaction, and post-processing to obtain the cerium-doped CQDs. However, the cerium in these CQDs is a heavy metal, raising certain biosafety concerns. Summary of the Invention

[0004] The first object of the present invention is to provide a method for preparing carbon quantum dots based on cysteine ​​and glucose to solve the technical problem that existing quantum dots are doped with heavy metals and have certain biosafety concerns.

[0005] The second object of the present invention is to provide carbon quantum dots based on cysteine ​​and glucose.

[0006] The third object of the present invention is to provide an application of carbon quantum dots based on cysteine ​​and glucose.

[0007] In order to achieve the above objectives, the technical solution adopted by the present invention is:

[0008] The preparation method of carbon quantum dots based on cysteine ​​and glucose includes the following steps: mixing cysteine, glucose and a solvent to obtain a reaction solution, adjusting the reaction solution to alkalinity, and preparing the carbon quantum dots by microwave-assisted pyrolysis.

[0009] Furthermore, the cysteine ​​is L-cysteine ​​or D-cysteine.

[0010] Furthermore, the molar ratio of the cysteine ​​to the glucose is 1:1-1:2, and 10-15 mL of the solvent is added for every 0.2908 g of the cysteine.

[0011] Furthermore, the solvent is water.

[0012] Furthermore, the temperature of the microwave-assisted pyrolysis is 140-160° C., and the time of the microwave-assisted pyrolysis is 10-30 min.

[0013] Furthermore, the pH of the reaction solution is 11-12.

[0014] Furthermore, the reaction solution is subjected to microwave-assisted pyrolysis to obtain a carbon quantum dot dispersion, which is cooled to 50-60° C., then transferred to a dialysis bag for purification, and freeze-dried to obtain the product.

[0015] The carbon quantum dots based on cysteine ​​and glucose are prepared by using the above-mentioned preparation method of the carbon quantum dots based on cysteine ​​and glucose.

[0016] Application of cysteine ​​and glucose-based carbon quantum dots in salt stress resistance of pea.

[0017] Beneficial effects of the present invention:

[0018] The cysteine ​​and glucose-based carbon quantum dots of the present invention do not introduce heavy metal elements and are environmentally friendly. They can alleviate salt stress in peas by enhancing antioxidant defenses, protecting the photosynthetic system, optimizing osmotic regulation, regulating protein protection and repair, and integrating signal transduction with metabolic regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 HRTEM images of carbon quantum dots based on cysteine ​​and glucose in Examples 1-2, wherein a is Example 1 and b is Example 2;

[0020] Figure 2 Circular dichroism spectra of carbon quantum dots based on cysteine ​​and glucose in Example 1-2;

[0021] Figure 3 This is the UV-visible absorption spectrum of carbon quantum dots based on cysteine ​​and glucose in Example 1-2;

[0022] Figure 4 The fluorescence spectra of carbon quantum dots based on cysteine ​​and glucose in Examples 1-2, wherein a is Example 1 and b is Example 2;

[0023] Figure 5FTIR spectra of carbon quantum dots based on cysteine ​​and glucose in Example 1-2;

[0024] Figure 6 This is a diagram showing the ABTS·+ removal effect of carbon quantum dots based on cysteine ​​and glucose in Example 1-2;

[0025] Figure 7 This is a diagram showing the DPPH· scavenging effect of carbon quantum dots based on cysteine ​​and glucose in Example 1-2;

[0026] Figure 8 This is a diagram showing the PTIO· clearance effect of carbon quantum dots based on cysteine ​​and glucose in Example 1-2;

[0027] Figure 9 This is a diagram showing the O2·- scavenging effect of carbon quantum dots based on cysteine ​​and glucose in Example 1-2;

[0028] Figure 10 This is a diagram showing the OH removal effect of carbon quantum dots based on cysteine ​​and glucose in Example 1-2;

[0029] Figure 11 The 1O2 removal effect diagram of carbon quantum dots based on cysteine ​​and glucose in Example 1-2

[0030] Figure 12 This is a graph showing the germination rate of peas under salt stress after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1;

[0031] Figure 13 Figure 1 is a graph showing the root number of peas under salt stress after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1;

[0032] Figure 14 Figure 1 is a diagram showing the root growth of peas under salt stress after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1;

[0033] Figure 15 Graph showing the moisture content of peas under salt stress after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1;

[0034] Figure 16 Figure 2 is a graph showing the malondialdehyde content in peas under salt stress after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1;

[0035] Figure 17 Graph showing the proline content in peas under salt stress after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1;

[0036] Figure 18Graph showing the soluble sugar content in peas after treatment with the carbon quantum dots of Examples 1-2 and Comparative Example 1 under salt stress;

[0037] Figure 19 This is a heat map showing the correlation between the protein expression levels of samples A, B, C, and D in Experiment 1.

[0038] Figure 20 This is the difference in protein expression between group A and group B;

[0039] Figure 21 This is the difference in protein expression between group B and group C;

[0040] Figure 22 This is the difference in protein expression between group B and group D;

[0041] Figure 23 The difference in protein expression between group C and group D is shown. DETAILED DESCRIPTION

[0042] The present invention will be further described below with reference to the embodiments of the present invention and the accompanying drawings.

[0043] Pea pretreatment: Sterilize the pea seeds in a 1:40 diluted 84 disinfectant solution for 20 minutes and rinse with distilled water 5 times.

[0044] CK group: Pretreated pea seeds were soaked in a Petri dish filled with 35 mL of distilled water for 18 hours for initiation. After initiation, pea seeds of similar size were wiped with filter paper and rolled between two layers of filter paper. The pea seeds were then placed in a Petri dish filled with 10 mL of growth medium. The bottom of the Petri dish was covered with filter paper, and the growth medium was distilled water. The Petri dish was placed at 25°C, 90% relative humidity, and darkness. After 7 days of incubation, the physiological and biochemical indicators of the peas (seed germination rate, root activity, root length, and biomass) were measured. The germination rate was assessed by recording the number of pea seeds germinated every 6 hours. To ensure the accuracy of the test data, all experiments were repeated three times.

[0045] Salt group: The pretreated pea seeds were soaked in a culture dish filled with 35 mL of distilled water for 18 h for induction. After induction, pea seeds of similar size were wiped with filter paper and rolled in two layers of filter paper. The pea seeds were then placed in a culture dish filled with 10 mL of growth medium. The bottom of the culture dish was covered with filter paper, and the growth medium was 200 mM NaCl solution. The culture dish was placed at 25°C, 90% relative humidity and dark conditions. After culturing for 7 days, the physiological and biochemical indicators of peas were measured. The germination rate was evaluated by recording the number of pea seeds germinated every 6 h. In order to ensure the accuracy of the test data, all experiments were repeated three times.

[0046] In the Salt + L-CDs group, pretreated pea seeds were immersed in a Petri dish containing a 0.09 mg / mL L-CDs solution for 18 hours for initiation. After initiation, pea seeds of similar size were wiped with filter paper and rolled between two layers of filter paper. The seeds were then placed in a Petri dish containing 10 mL of growth medium. The bottom of the Petri dish was lined with filter paper, and the growth medium consisted of a 200 mM NaCl solution. The Petri dishes were incubated at 25°C, 90% relative humidity, and darkness for 7 days. Physiological and biochemical parameters of the peas were then measured. Germination rate was assessed by recording the number of pea seeds that germinated every 6 hours. To ensure data accuracy, all experiments were repeated three times.

[0047] In the Salt + D-CDs group, pretreated pea seeds were immersed in a Petri dish containing a 0.09 mg / mL D-CDs solution for 18 hours for initiation. After initiation, pea seeds of similar size were wiped with filter paper and rolled between two layers of filter paper. The seeds were then placed in a Petri dish containing 10 mL of growth medium. The bottom of the Petri dish was lined with filter paper, and the growth medium consisted of a 200 mM NaCl solution. The Petri dishes were incubated at 25°C, 90% relative humidity, and darkness for 7 days. Physiological and biochemical parameters of the peas were then measured. Germination rate was assessed by recording the number of pea seeds that germinated every 6 hours. To ensure data accuracy, all experiments were repeated three times.

[0048] In the Salt + A-CDs group, pretreated pea seeds were immersed in a Petri dish containing a 0.09 mg / mL A-CDs solution for 18 hours for initiation. After initiation, pea seeds of similar size were wiped with filter paper and rolled between two layers of filter paper. The seeds were then placed in a Petri dish containing 10 mL of growth medium. The bottom of the Petri dish was lined with filter paper, and the growth medium consisted of a 200 mM NaCl solution. The Petri dishes were incubated at 25°C, 90% relative humidity, and darkness for 7 days. Physiological and biochemical parameters of the peas were then measured. Germination rate was assessed by recording the number of pea seeds that germinated every 6 hours. To ensure data accuracy, all experiments were repeated three times.

[0049] Example 1

[0050] The preparation method of carbon quantum dots based on cysteine ​​and glucose in Example 1 comprises the following steps: dissolving 0.2908 g of L-cysteine ​​and 0.4324 g of glucose in 10 mL of deionized water to obtain a reaction solution, adjusting the pH value of the reaction solution to 11 with a 4 mol / L NaOH solution, then transferring the reaction solution to the lining of the reactor, microwave-assisted heating at 140 ° C for 10 min, and naturally cooling to 60 ° C to obtain a brown-red carbon quantum dot (CDs) dispersion. The CDs dispersion was transferred to a 500 Da dialysis bag for dialysis treatment for 24 h, then frozen for 12 h, and dried for 48 h to obtain brown-yellow solid powder carbon quantum dots. The carbon quantum dots in Example 1 are named L-CDs.

[0051] Example 2

[0052] The preparation method of carbon quantum dots based on cysteine ​​and glucose in Example 2 comprises the following steps: dissolving 0.2908 g of L-cysteine ​​and 0.4324 g of glucose in 10 mL of deionized water to obtain a reaction solution, adjusting the pH value of the reaction solution to 11 with a 4 mol / L NaOH solution, then transferring the reaction solution to the lining of a reactor, heating it with microwave assistance at 140°C for 10 min, cooling it naturally to 60°C, and then taking it out to obtain a brown-red CDs dispersion, transferring the CDs dispersion to a 500Da dialysis bag for 24 h of dialysis, then freezing it for 12 h, and drying it for 48 h to obtain carbon quantum dots. The carbon quantum dots in Example 2 are named D-CDs.

[0053] Example 3

[0054] The preparation method of carbon quantum dots based on cysteine ​​and glucose in Example 3 includes the following steps: dissolving 0.2908 g of D-cysteine ​​and 0.8648 g of glucose in 15 mL of deionized water to obtain a reaction solution, adjusting the pH value of the reaction solution to 12 with 4 mol / L NaOH solution, then transferring the reaction solution to the lining of the reactor, microwave-assisted heating at 160°C for 15 min, and naturally cooling to 50°C to obtain a brown-red CDs dispersion. The CDs dispersion was transferred to a 500Da dialysis bag and dialyzed for 24 h, then frozen for 12 h, and dried for 48 h to obtain carbon quantum dots.

[0055] Example 4

[0056] The preparation method of carbon quantum dots based on cysteine ​​and glucose in Example 4 includes the following steps: dissolving 0.2908 g of D-cysteine ​​and 0.6536 g of glucose in 14 mL of deionized water to obtain a reaction solution, adjusting the pH value of the reaction solution to 11 with 4 mol / L NaOH solution, and then transferring the reaction solution to the lining of the reactor, heating it with microwave assisted heating at 150 ° C for 30 min, and naturally cooling it to 60 ° C to obtain a brown-red CDs dispersion. The CDs dispersion was transferred to a 500Da dialysis bag and dialyzed for 24 h, then frozen for 12 h, and dried for 48 h to obtain carbon quantum dots.

[0057] Comparative Example 1

[0058] The preparation method of the carbon quantum dots of Comparative Example 1 comprises the following steps: mixing 0.1454 g of L-cysteine ​​and 0.1454 g of D-cysteine ​​to form racemized cysteine, dissolving 0.2908 g of racemized cysteine ​​and 0.4324 g of glucose in 10 mL of deionized water to obtain a reaction solution, adjusting the pH value of the reaction solution to 11 with a 4 mol / L NaOH solution, then transferring the reaction solution to the lining of the reactor, heating it with microwave-assisted heating at 140° C. for 10 min, cooling it naturally to 60° C. and then taking it out to obtain a CDs dispersion, transferring the CDs dispersion to a 500Da dialysis bag for dialysis treatment for 24 h, and then freeze-drying it to obtain carbon quantum dots. The carbon quantum dots of Comparative Example 1 are named A-CDs.

[0059] from Figure 1 It can be seen that the average particle size of L-CDs and D-CDs is 2-3 nm, which shows good dispersibility. Figure 2 It can be seen from the circular dichroism spectra that both L-CDs and D-CDs exhibit symmetrical circular dichroism signals at 243 nm and 312 nm, indicating that L-CDs and D-CDs have obvious chirality. Figure 3 The UV-visible spectra of the mesochiral L-CDs and D-CDs showed broad absorption peaks, and the absorption at 260-280 nm was attributed to the π-π* transition of the aromatic ring C=C bond, indicating the formation of a graphitic carbon core in the carbon quantum dots.

[0060] from Figure 6-7 It can be seen that with the increase of carbon quantum dot concentration, the removal rate of ABTS·+ and DPPH· gradually increases, indicating that the carbon quantum dots of Example 1-2 have a good ability to remove active nitrogen. Figure 8 It can be seen that the carbon quantum dots of Examples 1-2 exhibit significant PTIO· scavenging ability, and the carbon quantum dots exhibit significant PTIO· quenching ability in a concentration-dependent manner. Figure 9-11It can be seen that the addition of the carbon quantum dots of Example 1-2 causes the ESR signal intensity to gradually decrease in a concentration-dependent manner, which indicates that the carbon quantum dots of Example 1-2 have excellent ability to scavenge reactive oxygen species (ROS).

[0061] from Figure 12 It can be seen that the germination rate of pea seeds under salt stress is significantly lower than that of the CK group, while the germination rate of pea seeds increases after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1, among which the carbon quantum dots of Example 1 have the best effect. Figure 13-14 It can be seen that the number of roots and root length of pea seeds after salt stress decreased significantly compared with the blank group, while the number of roots and root length of pea seeds increased after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1. Figure 15 It can be seen that the moisture content of pea seeds after salt stress is significantly reduced compared with the blank group, while the moisture content of pea seeds increased after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1. Figure 16-17 It can be seen that the malondialdehyde (MDA) and proline (PRO) contents of pea seeds subjected to salt stress increased significantly compared with the blank group. After being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1, the malondialdehyde and proline contents of pea seeds decreased. The malondialdehyde and proline contents of pea seeds treated with the carbon quantum dots in Example 1 were close to those of the blank group. Figure 18 It can be seen that the soluble sugar content of pea seeds after salt stress was significantly decreased compared with the blank group, while the soluble sugar content of pea seeds increased after being treated with the carbon quantum dots of Examples 1-2 and Comparative Example 1.

[0062] Reactive oxygen species in plants can significantly improve MDA levels through membrane lipid peroxidation. PRO and soluble sugars can effectively eliminate reactive oxygen species in plants and reduce MDA content, thereby reducing damage to plants under salt stress. Plants produce osmolytes and some useful solutes to protect them from the effects of salt stress by maintaining osmotic and ion balance. These osmotic regulating substances, such as MDA, soluble sugars, soluble proteins, and PRO, alleviate the tendency of plant cells to lose water, and adapt to salt stress by maintaining the stability of plant cell membranes and regulating the microenvironment within the plant body.

[0063] Test Example 1

[0064] Mechanism of cysteine ​​and glucose-based carbon quantum dots in alleviating salt stress resistance in peas

[0065] from Figure 19 As can be seen from the data, the correlations of the four groups of samples, A, B, C, and D, are all greater than 0.8, and can be used for subsequent analysis. Group A is the CK group, Group B is the Salt group, Group C is the Salt + L-CDs group, and Group D is the Salt + D-CDs group.

[0066] When FC≥2 and Pvalue≤0.05, up-regulated proteins were selected; when FC≤1 / 2 and Pvalue≤0.05, down-regulated proteins were selected. The number of up-regulated and down-regulated proteins selected according to this condition is shown in Table 1. The differentially expressed proteins in groups A_vs_B, B_vs_C and B_vs_D were analyzed.

[0067] Table 1 Statistics of differentially expressed proteins

[0068]

[0069] from Figure 20It can be seen that under salt stress, the proteins upregulated in pea seeds include: Dehydrin (dehydrin) antioxidant protein; Water stress and hypersensitive response domain-containing protein osmotic pressure regulating protein; Ribosomal protein (ribosomal protein), Peptide-methionine (R)-S-oxide reductas, UBAdomain-containing protein protein protection-related protein; EF-handdomain-containing protein (EF-hand domain protein) signal transduction-related protein; Seedmaturation protein, Cvc protein, Oleosin and other seed vitality-related proteins; The proteins downregulated in pea seeds include: Peroxidase (peroxidase) antioxidant enzyme; Transketolase (transketolase) photosynthesis-related enzyme; Pyrrolidone-carboxylate peptidase (hydroxyproline peptidase) protein protection-related enzyme; Subtilisin-like protease (subtilisin-like protease), Bet v I / Major latex proteindomain-containing protein, Phytocyanin domain-containing protein (phytocyanin domain protein), Remorin (membrane-anchored protein), Soyasaponin III rhamnosyltransferase (soy saponin III rhamnosyltransferase) and other signal transduction-related enzymes; Pectinesterase inhibitor domain-containing protein, Fasciclin-like arabinogalactan protein, Pectinesterase and other cell wall-related proteins; Carbamoyl-phosphate synthase (glutamine-hydrolyzing) (CPS, glutamine hydrolyzing type), Asparagine synthetase [glutamine-hydrolyzing] (AS, glutamine hydrolyzing type) and other amino acid metabolism-related proteins.

[0070] Under 200 mM NaCl salt stress, the pea seed proteome underwent significant changes, with 61 differentially expressed proteins identified, including 26 upregulated and 35 downregulated proteins involved in multiple functional modules, including antioxidant defense, photosynthesis, osmotic regulation, and signaling. The antioxidant system exhibited bidirectional regulation: stress proteins such as dehydrin were upregulated to indirectly enhance reactive oxygen species scavenging capacity, while the activity of direct antioxidant enzymes such as peroxidase was inhibited, indicating that salt stress leads to an imbalance in reactive oxygen species metabolism. Downregulation of photosynthesis-related enzymes, such as transketolase, suggests that salt stress responds to oxidative stress by inhibiting the nonoxidative phase of the pentose phosphate pathway, prioritizing NADPH production and impairing photosynthetic efficiency. Osmotic regulation maintains cellular water balance through the upregulation of proteins such as WHy, while proteostasis manifests as upregulation of ribosomal proteins and repair enzymes to maintain essential protein synthesis, while downregulation of degradation enzymes reduces energy expenditure. Upregulation of EF-hand proteins in signaling activates calcium-dependent defense pathways, while downregulation of signaling-related proteins such as subtilisin-like protease may optimize stress response priorities. Downregulation of proteins involved in cell wall synthesis and modification (such as pectin esterase inhibitors) reflects a shift in energy toward stress resistance, while inhibition of amino acid metabolism enzymes (such as CPS and AS) supports stress adaptation by limiting nitrogen consumption. Furthermore, upregulation of seed viability-related proteins (such as Oleosin) suggests that seeds maintain their germination potential by enhancing stress tolerance reserves. Overall, pea seeds achieve a dynamic balance between energy optimization and stress adaptation by inhibiting growth and non-essential metabolism (such as secondary metabolism and photosynthesis) and reallocating resources to core salt-resistance pathways, including ion homeostasis, reactive oxygen species scavenging, and osmoprotection, providing a molecular basis for post-germination survival in adverse conditions.

[0071] from Figure 21It can be seen that after the treatment with L-CDs in Example 1, the upregulated proteins in pea seeds include: antioxidant proteins such as Thioredoxin and Glutathione S-transferase; photosynthesis-related proteins such as Chlorophyll AB binding protein; osmotic regulation-related proteins such as Homoserine dehydrogenase; protein protection-related proteins such as ICP0-binding domain of Ubiquitin-specific protease 7; signal transduction-related proteins such as VID27 C-terminal WD40-like domain; cell wall modification-related proteins such as pre-mRNA-splicing ATP-dependent RNA helicase prp28-like protein; Glutamineamidotransferases class-II (glutamine amidotransferase II) and other amino acid metabolism-related proteins; Cupin and other seed vitality-related proteins; down-regulated proteins in pea seeds include: Dehydrin and other antioxidant-related proteins; Seedbiotin-containing protein sbp65 and other osmotic regulation-related proteins; Eukaryotic translation initiation factor 3 subunit 8 N-terminus and other protein protection-related proteins; UDP-glucoronosyl and UDP-glucosyl transferase and other signal transduction-related proteins; Rhodanese-like domain and other amino acid modification-related proteins; Lateembryogenesis abundant (LEA) group 1 and other seed vitality-related proteins.

[0072] from Figure 22It can be seen that after the D-CDs treatment of Example 2, the upregulated proteins in pea seeds include: antioxidant-related proteins such as Peroxidase and Glutathione S-transferase; photosynthesis-related proteins such as Chlorophyll AB binding protein; osmotic regulation-related proteins such as Plantinvertase / pectin methylesterase inhibitor and Glycosyl hydrolasesfamily 38; protein protection-related proteins such as Ubiquitin family and Chaperonin; signal transduction-related proteins such as EF-1guanine nucleotide exchange domain and Adaptor complexesmedium subunit family; cell wall modification-related proteins such as Fasciclindomain and Subtilase family; tRNA synthetases class Proteins involved in amino acid metabolism, such as class I tRNA synthetase M and AMP-binding enzyme; and proteins involved in seed vigor, such as cupin. Proteins downregulated in pea seeds include antioxidant proteins such as dehydrin; osmotic regulation proteins such as seed maturation protein; protein synthesis proteins such as eIF4-gamma / eIF5 / eIF2-epsilon (eukaryotic translation initiation factors); signaling proteins such as tRNA synthetases class I (E and Q), catalytic domain; amino acid metabolism proteins such as seedbiotin-containing protein and aluminum-induced protein; and seed vigor proteins such as seed maturation protein and methyl-CpG binding domain.

[0073] L-CDs and D-CDs alleviate salt stress in peas through multiple mechanisms, including enhancing antioxidant defenses, protecting the photosynthetic system, optimizing osmotic regulation, coordinating protein protection and repair, integrating signal transduction and metabolic regulation, balancing cell wall modification and protection, adjusting amino acid metabolism and nitrogen utilization, and regulating seed viability and germination. These mechanisms work together to more effectively maintain cell stability, integrity, and functionality under salt stress, thereby achieving normal growth.

[0074] Table 2 Similarities and differences between L-CDs and D-CDs in alleviating salt stress in pea

[0075]

[0076]

[0077] As shown in Table 2, both L-CDs and D-CDs enhance antioxidant activity by upregulating antioxidant enzymes (such as glutathione S-transferase and peroxidase) to scavenge reactive oxygen species and mitigate oxidative damage. They also protect cells from oxidative damage by reducing salt-induced oxidative stress. Furthermore, both protect the photosynthetic system by upregulating related proteins (such as chlorophyll AB binding protein) to maintain photosynthetic efficiency, ensuring that plants can continue photosynthesis under salt stress and providing energy for growth. Regarding osmotic regulation, both L-CDs and D-CDs maintain intracellular osmotic balance by regulating osmotic pressure-related proteins, such as homoserine dehydrogenase and sodium-calcium exchanger, thereby reducing cellular dehydration caused by salt stress. Regarding protein protection and repair, both L-CDs and D-CDs maintain protein quality control within cells by upregulating protein protection proteins, such as molecular chaperones and ubiquitin family proteins, reducing the accumulation of misfolded and damaged proteins. In terms of integrating signal transduction with metabolic regulation, both L-CDs and D-CDs enhance plants' perception and response to salt stress by regulating signal transduction pathways (such as the EF-1 guanylate exchange domain and the adaptor complex subunit family).

[0078] However, L-CDs focus more on maintaining cellular homeostasis by enhancing protein protection and repair mechanisms. For example, L-CDs significantly upregulate proteins involved in protein repair (such as the ICP0-binding domain of ubiquitin-specific protease 7); proteins related to amino acid metabolism and nitrogen utilization (such as glutamine amidotransferase class II); and proteins associated with seed vigor and germination (such as cup proteins). They primarily regulate signal transduction by upregulating proteins related to protein repair and signal transduction (such as the ICP0-binding domain of ubiquitin-specific protease 7). D-CDs, on the other hand, focus more on maintaining cellular structural integrity by enhancing cell wall modification and protection. For example, D-cysteine ​​carbon dots significantly upregulated proteins related to cell wall modification (such as the bundle structure domain and the subtilisin family); significantly upregulated proteins related to seed maturation and germination (such as seed maturation proteins and methyl-CpG binding domains), and also upregulated photosynthesis-related proteins (such as chlorophyll AB binding protein); in addition to upregulating chlorophyll AB binding protein, it also further improved photosynthetic efficiency by upregulating key enzymes such as ribose bisphosphate carboxylase; and mainly regulated signal transduction by upregulating proteins related to the adapter complex and signal transduction (such as the subunit family in the adapter complex).

Claims

1. A method for preparing carbon quantum dots based on cysteine ​​and glucose, characterized in that: The following steps are involved: Cysteine, glucose and a solvent are mixed to obtain a reaction solution, the reaction solution is adjusted to alkalinity, and the solution is prepared by microwave-assisted pyrolysis.

2. The method for preparing carbon quantum dots based on cysteine ​​and glucose according to claim 1, wherein The cysteine ​​is L-cysteine ​​or D-cysteine.

3. The method for preparing carbon quantum dots based on cysteine ​​and glucose according to claim 1, wherein The molar ratio of the cysteine ​​to the glucose is 1:1-1:2, and 10-15 mL of the solvent is added for every 0.2908 g of the cysteine.

4. The method for preparing carbon quantum dots based on cysteine ​​and glucose according to claim 1 or 3, characterized in that, The solvent is water.

5. The method for preparing carbon quantum dots based on cysteine ​​and glucose according to claim 1, wherein The temperature of the microwave-assisted pyrolysis is 140-160° C., and the time of the microwave-assisted pyrolysis is 10-30 minutes.

6. The method for preparing carbon quantum dots based on cysteine ​​and glucose according to claim 1, characterized in that, The pH of the reaction solution is 11-12.

7. The method for preparing carbon quantum dots based on cysteine ​​and glucose according to claim 1, characterized in that: The reaction solution is subjected to microwave-assisted pyrolysis to obtain a carbon quantum dot dispersion, which is cooled to 50-60° C., then transferred to a dialysis bag for purification, and freeze-dried to obtain the product.

8. Carbon quantum dots based on cysteine ​​and glucose, characterized in that, The carbon quantum dots are prepared by the method for preparing carbon quantum dots based on cysteine ​​and glucose according to claim 1. 9 . Use of the cysteine ​​and glucose-based carbon quantum dots as claimed in claim 8 in resisting salt stress in pea.

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