title: Effect of size, surface charge, and hydrophobicity of poly(amidoamine) dendrimers on their skin penetration.
abstract: The barrier functions of the stratum corneum and the epidermal layers present a tremendous challenge in achieving effective transdermal delivery of drug molecules. Although a few reports have shown that poly(amidoamine) (PAMAM) dendrimers are effective skin-penetration enhancers, little is known regarding the fundamental mechanisms behind the dendrimer-skin interactions. In this Article, we have performed a systematic study to better elucidate how dendrimers interact with skin layers depending on their size and surface groups. Franz diffusion cells and confocal microscopy were employed to observe dendrimer interactions with full-thickness porcine skin samples. We have found that smaller PAMAM dendrimers (generation 2 (G2)) penetrate the skin layers more efficiently than the larger ones (G4). We have also found that G2 PAMAM dendrimers that are surface-modified by either acetylation or carboxylation exhibit increased skin permeation and likely diffuse through an extracellular pathway. In contrast, amine-terminated dendrimers show enhanced cell internalization and skin retention but reduced skin permeation. In addition, conjugation of oleic acid to G2 dendrimers increases their 1-octanol/PBS partition coefficient, resulting in increased skin absorption and retention. Here we report that size, surface charge, and hydrophobicity directly dictate the permeation route and efficiency of dendrimer translocation across the skin layers, providing a design guideline for engineering PAMAM dendrimers as a potential transdermal delivery vector.
authors.affiliation: Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois, Chicago, Illinois 60612, United States.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Suhair
authors.initials: S
authors.lastname: Sunoqrot
authors.forename: Chelsea
authors.initials: C
authors.lastname: Stowell
authors.forename: Jingli
authors.initials: J
authors.lastname: Ji
authors.forename: Chan-Woo
authors.initials: CW
authors.lastname: Lee
authors.forename: Jin Woong
authors.initials: JW
authors.lastname: Kim
authors.forename: Seema A
authors.initials: SA
authors.lastname: Khan
authors.forename: Seungpyo
authors.initials: S
authors.lastname: Hong
mesh_terms: D000107:Acetylation; D000818:Animals; D050091:Dendrimers / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D018613:Microscopy, Confocal; D010316:Particle Size; D010539:Permeability; D011073:Polyamines / Q000737:chemistry / Q000378:metabolism*; D012235:Rhodamines / Q000737:chemistry / Q000378:metabolism; D012867:Skin / Q000378:metabolism*; D013499:Surface Properties; D034421:Sus scrofa
chemical_list: D050091:Dendrimers; D005456:Fluorescent Dyes; C104700:PAMAM Starburst; C531249:Poly(amidoamine); D011073:Polyamines; D012235:Rhodamines