title: Colloidal stability of gold nanorod solution upon exposure to excised human skin: Effect of surface chemistry and protein adsorption.
abstract: In this study, we evaluated the colloidal stability of gold nanorods (with positive, negative and neutral surface charge) in solution upon contact with excised human skin. UV-vis absorption, plasmon peak broadening index (PPBI%) and transmission electron microscope analysis were used to follow nanoparticles aggregation in solution. Our results show that positively charged gold nanorods aggregate extensively upon exposure to excised human skin compared to negatively and neutrally charged gold nanorods. Skin-induced aggregation of cationic gold nanorods was linked to the adsorption of proteins released from the dermis layer to the surface of gold nanorods. Protein adsorption significantly screen nanorod's effective surface charge and induce their aggregation. Moreover, we demonstrate that the presence of polyethylene glycol polymer on the surface of cationic gold nanorods minimize this aggregation significantly by providing steric repulsion (non-electrostatic stabilization mechanism). This work highlights the importance of evaluating the colloidal stability of nanoparticles in solution upon contact with skin, which is a "usually overlooked" parameter when studying the nanoparticle-skin interaction.
authors.affiliation: Department of Pharmaceutics & Pharmaceutical Technology, Faculty of Pharmacy, The University of Jordan, Amman 11942, Jordan.
authors.forename: Nouf N
authors.initials: NN
authors.lastname: Mahmoud
authors.affiliation: Department of Biological Sciences, Yarmouk University, Irbid, Jordan.
authors.forename: Khaled M
authors.initials: KM
authors.lastname: Al-Qaoud
authors.affiliation: Department of Pharmaceutics & Pharmaceutical Technology, Faculty of Pharmacy, The University of Jordan, Amman 11942, Jordan.
authors.forename: Amal G
authors.initials: AG
authors.lastname: Al-Bakri
authors.affiliation: Department of Pharmaceutics & Pharmaceutical Technology, Faculty of Pharmacy, The University of Jordan, Amman 11942, Jordan. Electronic address: a.alkilany@ju.edu.jo.
authors.forename: Alaaldin M
authors.initials: AM
authors.lastname: Alkilany
authors.affiliation: Department of Pharmaceutics & Pharmaceutical Technology, Faculty of Pharmacy, The University of Jordan, Amman 11942, Jordan.
authors.forename: Enam A
authors.initials: EA
authors.lastname: Khalil
mesh_terms: D000327:Adsorption; D000328:Adult; D003102:Colloids; D004355:Drug Stability; D005260:Female; D006046:Gold / Q000737:chemistry*; D006801:Humans; D043942:Nanotubes / Q000737:chemistry*; D011073:Polyamines / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D012867:Skin / Q000378:metabolism*; D012996:Solutions; D013499:Surface Properties
chemical_list: D003102:Colloids; D011073:Polyamines; D011506:Proteins; D012996:Solutions; C063994:polyallylamine; D011092:Polyethylene Glycols; D006046:Gold
keywords: Colloidal stability; Dermis; Epidermis; Gold nanorods; Human skin; Nanoparticles; Stratum corneum