10.4 Biological Implications of Biodegradable Dendrimers 257 in the form of highly branched dendritic architectures  . The interesting applica- tion of these intriguing and well - deﬁ ned materials seems to be branching out. Especially, they offer water solubility due to enriched hydrophilic groups at the surface, ester linkages to make them biodegradable, and appropriate amounts of drug can be added so that a uniform supply of the drug is delivered when the polymer degrades. Dendrimers ﬁ nd implications in biology for delivering drugs, bioactives (e.g., SiRNA and peptides), diagnostics (dyes), and in targeted delivery systems (use of LHRH peptide, folic acid, antibodies, etc.) [14, 21, 22, 37, 43, 44] . Among many other crucial characteristics of cellular internalization of dendritic architectures, the ability of dendrimers to cross cell membrane is of much interest particularly for their application in drug and gene delivery. A recent study has demonstrated that dendrimers are capable to enter cells by endocytosis, but the intracellular pathway following their internalization remains controversial  . The intracellular trafﬁ cking property of PAMAM dendrimers was observed using confocal ﬂ uorescence microscopy with high spatial and temporal resolution in living HeLa cells. Macromolecules of different chemical functionality (neutral, cationic, and lipidated), size (from G2 up to G6), and surface charge are investi- gated and their internalization properties correlated with the molecular structure. So far, not many strategies have been reported to synthesize biodegradable den- drimers and among them very few suggest their biomedical applications. Section 10.5 highlights biological perspectives of biodegradable dendrimers.