The use of nanosized materials changes the way in which drugs are handled by the body and offers opportunities to improve drug delivery. The physiological mechanisms controlling the distribution of nanosized materials (enhanced permeability and retention effect, cellular uptake pathways and opsonisation/elimination of nanoparticles) are described. Two different nanosized drug delivery systems are considered; drug delivery and DNA delivery. The deficiencies of currently available biodegradable polymers for preparation of drug containing nanoparticles are mainly the amount of drug that can be incorporated and the rapid rate of drug release. The development of new biodegradable polymers which can interact with the drug and so significantly increase drug loading and decrease the rate of drug release are outlined. DNA delivery necessitates overcoming a variety of biological barriers. We are developing polyelectrolyte complexes of DNA with cationic polyamidoamines (PAA) as a delivery system. Complexing PAA with DNA results in good transfection of cells in vitro. However, in vivo, a more complex arrangement of PAA, Polyethylene glycol-PAA copolymers, DNA and the use of ligands will be required. Despite these efforts, further developments will be needed in nanotechnology for both drug and DNA nanoparticle delivery systems to achieve our clinical objectives.
A self-assembling amphiphilic peptide nanoparticle for the efficient entrapment of DNA cargoes up to 100 nucleotides in length