title: Cell-specific aptamers and their conjugation with nanomaterials for targeted drug delivery.
abstract: BACKGROUND
  Aptamers are short, single-stranded DNA or RNA sequences that can fold into complex secondary and tertiary structures and bind to various target molecules with high affinity and specificity. These properties, as well as rapid tissue penetration and ease of chemical modification, make aptamers ideal recognition elements for in vivo targeted drug delivery and attractive molecules for use in disease diagnosis and therapy.
  
  
  METHODS
  The general properties of aptamers as well as advantages over their counterpart antibodies are briefly discussed. Next, aptamer selection by cell- systematic evolution of ligands by exponential enrichment is described in detail. Finally, the review summarizes recent progress in the field of targeted drug delivery based on aptamers and their conjugation to liposomes, micelles and other nanomaterials.
  
  
  CONCLUSIONS
  Advances in nanotechnology have led to new and improved nanomaterials for biomedical applications. Conjugation of nanoparticles (NPs) with aptamers exploits both technologies, making aptamer-NP conjugates ideal agents for drug delivery with proven therapeutic effects and the reduction of toxicity to normal tissue. The use of multivalent aptamer-conjugated nanomaterials represents one of the new directions for drug development in the future; as such, continuing studies of these multivalent aptamers and bioconjugates should result in important clinical applications in targeted drug delivery.
authors.affiliation: Central South University, Xiang Ya Hospital , Changsha , China.
authors.forename: Jie
authors.initials: J
authors.lastname: Liao
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Jiani
authors.initials: J
authors.lastname: Zhang
authors.forename: Ke
authors.initials: K
authors.lastname: Chen
authors.forename: Huixia
authors.initials: H
authors.lastname: Liu
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015415:Biomarkers; D004337:Drug Carriers / Q000737:chemistry*; D008024:Ligands; D008823:Micelles; D053758:Nanoparticles / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D009841:Oligonucleotides / Q000378:metabolism; D010789:Phototherapy / Q000379:methods; D034741:RNA, Small Interfering / Q000008:administration & dosage
chemical_list: D052157:Aptamers, Nucleotide; D015415:Biomarkers; D004337:Drug Carriers; D008024:Ligands; D008823:Micelles; D009841:Oligonucleotides; D034741:RNA, Small Interfering
keywords: aptamer; cell-systematic evolution of ligands by exponential enrichment; nanomaterials; targeted drug delivery