Invited Speaker

Aptamer therapeutics: the 21st century’s magic bullet of nanomedicine
Wei Duan
Australia

Aptamers, also known as chemical antibodies, are short single-stranded DNA, RNA or peptide molecules that can fold into complex three-dimensional structures and bind to target molecules with high affinity and specificity. The nucleic acid aptamers are selected from combinatorial libraries by an iterative in vitro selection procedure known as systematic evolution of ligands by exponential enrichment (SELEX). As a new class of therapeutics and drug targeting entities, bivalent and multivalent aptamer-based molecules are emerging as highly attractive alternatives to monoclonal antibodies in targeted therapeutics.

Aptamers have several advantages that offer the possibility of overcoming limitations of antibodies: 1) They can be selected against toxic or non-immunogenic targets; 2) Aptamers can be chemically modified by using modified nucleotides to enhance their stability in biological fluids or via incorporating reporter molecules, radioisotopes and functional groups for their detection and immobilization; 3) They have very low immunogenicity; 4) They display high stability at room temperature, in extreme pH, or solvent; 5) Once selected, they can be chemically synthesized free from cell-culture-derived contaminants, and they can be manufactured at any time, in large amounts, at relatively low cost and reproducibly; 6) They are smaller and thus can diffuse more rapidly into tissues and organs, leading to faster targeting in drug delivery; 7) They have lower molecular weight that can lead to faster body clearance, resulting in a low background noise for imaging and minimizing the radiation dose to the patient in diagnostic imaging. Thus, the versatility, high selectivity and sensitivity, ease of screening and production, chemical versatility as well as stability make aptamers a class of highly attractive agents for novel therapeutics, targeted drug delivery and molecular imaging.

The latest technological advances in developing aptamers, its application as a novel class of drug on its own as well as in surface functionalization of both polymer nanoparticles or nanoliposomes in the treatment of cancer, viral and autoimmune diseases will be discussed.