The present proposals relate to the delivery of nucleic acids to
plant cells and particularly, although not exclusively, to bioengineering of plants by delivery of
DNA and expression in a host
plant. The proposals also relates to enhancement of
photosynthesis in plants and to algaecidal compositions. In these proposals, the CND compound has the formula: CND-[(L)y-X] in which: CND is a carbon
nanodot having a
diameter in the range 0.5-20 nm; L is a
linker selected from C1-20 alkylene, or C1-20 alkenylene groups optionally including 1-5 heteroatoms selected from —O—, —N(H)—, and —S—; X is selected from: a) PEG-(NR2)q, in which each R is independently H or C1-6
alkyl and the integer q is 0 or 1 and in which the PEG-(NR2)q is optionally associated with a
nucleic acid; b) a
sugar moiety; and c) an NR2 group, in which each R is independently H or C1-6
alkyl wherein PEG is a
polyethylene glycol having a weight average molecular weight (Mw) greater than 200 the integer y is 0 or 1; wherein when y is 1, each of the CND and X moieties is attached to the L group either directly or via an
amide bond; and z is an integer greater than or equal to 1.