title: Cell-penetrating peptides and their analogues as novel nanocarriers for drug delivery.
abstract: BACKGROUND
  The impermeability of biological membranes is a major obstacle in drug delivery; however, some peptides have transition capabilities of biomembranes. In recent decades, cell-penetrating peptides (CPPs) have been introduced as novel biocarriers that are able to translocate into the cells. CPPs are biologically potent tools for non-invasive cellular internalization of cargo molecules. Nevertheless, the non-specificity of these peptides presents a restriction for targeting drug delivery; therefore, a peptidic nanocarrier sensitive to matrix metalloproteinase (MMP) has been prepared, called activatable cell-penetrating peptide (ACPP). In addition to the cell-penetrating peptide dendrimer (DCPP), other analogues of CPPs have been synthesized.
  
  
  METHODS
  In this study, the most recent literature in the field of biomedical application of CPPs and their analogues, ACPP and DCCP, were reviewed.
  
  
  RESULTS
  This review focuses on CPP and its analogues, ACPP and DCPP, as novel nanocarriers for drug delivery. In addition, nanoconjugates and bioconjugates of these peptide sequences are discussed.
  
  
  CONCLUSIONS
  DCCP, branched CPPs, compared to linear peptides have advantages such as resistance to rapid biodegradation, high loading capacities and large-scale production capability.
authors.affiliation: Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, Tabriz, Iran ; Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Samira
authors.initials: S
authors.lastname: Jafari
authors.affiliation: Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, Tabriz, Iran ; Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Solmaz
authors.initials: S
authors.lastname: Maleki Dizaj
authors.affiliation: Drug Applied Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Khosro
authors.initials: K
authors.lastname: Adibkia
keywords: Cell-penetrating peptides; Conjugation; Dendrimer; Nanoparticles; Targeted drug delivery; Translocation