Synthesis of functionalised gold nanoparticles and nanocompounds containing same for measuring sucrose or starch in cells

Method for the measurement of sucrose or starch in in plant cells which comprises the steps of:

• a) Synthesizing gold nanoparticles (AuNPs) in solution with citric acid;
• b) Functionalizing the synthesized gold nanoparticles obtained in step a) with the polymeric ligands SH(CH2)12COOH to provide a polymer functionalized AuNPs and dispersing a defined concentration of the polymer functionalized AuNPs to provide a polymer functionalized AuNPs solution;
• c) Adding half a portion of the polymer functionalized AuNPs solution obtained in step b) to a cytosol solution or a chloroplast solution obtained from the plant cells;
• d) Resting until achieving thermal equilibrium of the solution obtained in c);
• e) Adding a defined concentration of fluorescein to the remaining half portion of the polymer functionalized AuNPs solution of step b);
• f) Adding the same defined concentration of fluorescein used in step e), to the thermal equilibrated solution obtained in step d) having the polymer functionalized AuNPs solution and the cytosol or chloroplast solution;
• g) Measuring fluorescence intensity of the solution obtained in step e) and step f) and obtaining a net intensity of fluorescence from the difference of the measured fluorescence intensity of the solution between step e) and step f);
• and
• h) measuring the concentration of UDP-glucose or ADP-glucose as a function of the measured net intensity obtained in step g), and determining the concentration of sucrose or starch in the cytosol solution or the chloroplast solution from the measured concentration of the UDP-glucose or the ADP-glucose.