spread of particles 12 to 15 fold suggesting a significantly improved delivery of particles onto a large number of site in a biologically active manner in the leaf tissue this example illustrates the combined effect of both heat pretreatment of particles followed by use of isopropanol during coating of dna as superior to any one of these inventions taken separately the results show that while each of the two inventions gives substantial advantage over the standard protocol both the inventions employed together are synergistic and give much better results in terms of both expression of the delivered gene and uniformity of spread of the delivered particles in this example the following four combinations were compared for each of the old and the new particles i particles without heat pretreatment and coated with dna in ethanol i e standard protocol ii particles with heat treatment invention 1 and use of ethanol during dna coating as per standard protocol iii particles without heat pretreatment and coated with dna in isopropanol invention 2 substituted at all the steps instead of ethanol iv particles with heat treatment invention 1 as well as use of isopropanol instead of ethanol invention 2 during dna coating the above four treatments were applied to both old batch of gold particles as well as the new batch as seen in table 5 the heating pretreatment.