title: Charge-transfer interactions induce surface dependent conformational changes in apolipoprotein biocorona.
abstract: Upon introduction into a biological system, engineered nanomaterials (ENMs) rapidly associate with a variety of biomolecules such as proteins and lipids to form a biocorona. The presence of "biocorona" influences nano-bio interactions considerably, and could ultimately result in altered biological responses. Apolipoprotein A-I (ApoA-I), the major constituent of high-density lipoprotein (HDL), is one of the most prevalent proteins found in ENM-biocorona irrespective of ENM nature, size, and shape. Given the importance of ApoA-I in HDL and cholesterol transport, it is necessary to understand the mechanisms of ApoA-I adsorption and the associated structural changes for assessing consequences of ENM exposure. Here, the authors used a comprehensive array of microscopic and spectroscopic tools to elucidate the interactions between ApoA-I and 100 nm Ag nanoparticles (AgNPs) with four different surface functional groups. The authors found that the protein adsorption and secondary structural changes are highly dependent on the surface functionality. Our electrochemical studies provided new evidence for charge transfer interactions that influence ApoA-I unfolding. While the unfolding of ApoA-I on AgNPs did not significantly change their uptake and short-term cytotoxicity, the authors observed that it strongly altered the ability of only some AgNPs to generate of reactive oxygen species. Our results shed new light on the importance of surface functionality and charge transfer interactions in biocorona formation.
authors.affiliation: Laboratory of Nano-Biophysics, Clemson Nanomaterials Center, Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634.
authors.forename: Achyut J
authors.initials: AJ
authors.lastname: Raghavendra
authors.affiliation: Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Science, University of Colorado-Anschutz Medical Campus, Aurora, Colorado 80045.
authors.forename: Nasser
authors.initials: N
authors.lastname: Alsaleh
authors.affiliation: Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Science, University of Colorado-Anschutz Medical Campus, Aurora, Colorado 80045.
authors.forename: Jared M
authors.initials: JM
authors.lastname: Brown
authors.affiliation: Laboratory of Nano-Biophysics, Clemson Nanomaterials Center, Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 and Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson, South Carolina 29625.
authors.forename: Ramakrishna
authors.initials: R
authors.lastname: Podila
mesh_terms: D000818:Animals; D016632:Apolipoprotein A-I / Q000737:chemistry* / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002942:Circular Dichroism; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry; D051379:Mice; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry* / Q000633:toxicity; D011094:Polyethyleneimine / Q000737:chemistry; D017433:Protein Structure, Secondary; D000067996:RAW 264.7 Cells; D017382:Reactive Oxygen Species / Q000378:metabolism; D012834:Silver / Q000737:chemistry; D013499:Surface Properties; D008063:Thioctic Acid / Q000737:chemistry
chemical_list: D016632:Apolipoprotein A-I; D017382:Reactive Oxygen Species; D012834:Silver; D008063:Thioctic Acid; D011094:Polyethyleneimine