title: Effect of carbon black nanomaterial on biological membranes revealed by shape of human erythrocytes, platelets and phospholipid vesicles.
abstract: BACKGROUND
  We studied the effect of carbon black (CB) agglomerated nanomaterial on biological membranes as revealed by shapes of human erythrocytes, platelets and giant phospholipid vesicles. Diluted human blood was incubated with CB nanomaterial and observed by different microscopic techniques. Giant unilamellar phospholipid vesicles (GUVs) created by electroformation were incubated with CB nanomaterial and observed by optical microscopy. Populations of erythrocytes and GUVs were analyzed: the effect of CB nanomaterial was assessed by the average number and distribution of erythrocyte shape types (discocytes, echinocytes, stomatocytes) and of vesicles in test suspensions, with respect to control suspensions. Ensembles of representative images were created and analyzed using computer aided image processing and statistical methods. In a population study, blood of 14 healthy human donors was incubated with CB nanomaterial. Blood cell parameters (concentration of different cell types, their volumes and distributions) were assessed.
  
  
  RESULTS
  We found that CB nanomaterial formed micrometer-sized agglomerates in citrated and phosphate buffered saline, in diluted blood and in blood plasma. These agglomerates interacted with erythrocyte membranes but did not affect erythrocyte shape locally or globally. CB nanomaterial agglomerates were found to mediate attractive interaction between blood cells and to present seeds for formation of agglomerate - blood cells complexes. Distortion of disc shape of resting platelets due to incubation with CB nanomaterial was not observed. CB nanomaterial induced bursting of GUVs while the shape of the remaining vesicles was on the average more elongated than in control suspension, indicating indirect osmotic effects of CB nanomaterial.
  
  
  CONCLUSIONS
  CB nanomaterial interacts with membranes of blood cells but does not have a direct effect on local or global membrane shape in physiological in vitro conditions. Blood cells and GUVs are convenient and ethically acceptable methods for the study of effects of various substances on biological membranes and therefrom derived effects on organisms.
authors.affiliation: Laboratory of Clinical Biophysics, University of Ljubljana, Faculty of Health Sciences, Zdravstvena pot 5, Ljubljana, SI-1000, Slovenia. manca.pajnic@zf.uni-lj.si.
authors.forename: Manca
authors.initials: M
authors.lastname: Pajnič
authors.affiliation: Group of Nanobiology and Nanotoxicology, University of Ljubljana, Biotechnical Faculty, Večna pot 111, Ljubljana, SI-1000, Slovenia. barbara.drasler@gmail.com.
authors.forename: Barbara
authors.initials: B
authors.lastname: Drašler
authors.affiliation: Lymphocyte Cytoskeleton Group, Institute of Biomedicine/Pathology, BioCity, University of Turku, Tykistökatu 6B, Turku, SF-20520, Finland. vid.sustar@gmail.com.
authors.forename: Vid
authors.initials: V
authors.lastname: Šuštar
authors.affiliation: Laboratory of Clinical Biophysics, University of Ljubljana, Faculty of Health Sciences, Zdravstvena pot 5, Ljubljana, SI-1000, Slovenia. juditalea.krek@gmail.com.
authors.forename: Judita Lea
authors.initials: JL
authors.lastname: Krek
authors.affiliation: Laboratory of Clinical Biophysics, University of Ljubljana, Faculty of Health Sciences, Zdravstvena pot 5, Ljubljana, SI-1000, Slovenia. rstukelj@gmail.com.
authors.forename: Roman
authors.initials: R
authors.lastname: Štukelj
authors.affiliation: Laboratory of Clinical Biophysics, University of Ljubljana, Faculty of Health Sciences, Zdravstvena pot 5, Ljubljana, SI-1000, Slovenia. simundicme@yahoo.com.
authors.forename: Metka
authors.initials: M
authors.lastname: Šimundić
authors.affiliation: Group of Nanobiology and Nanotoxicology, University of Ljubljana, Biotechnical Faculty, Večna pot 111, Ljubljana, SI-1000, Slovenia. veno.kononenko@bf.uni-lj.si.
authors.forename: Veno
authors.initials: V
authors.lastname: Kononenko
authors.affiliation: J. Stefan Institute, Jamova 39, Ljubljana, SI-1000, Slovenia. darko.makovec@ijs.si.
authors.forename: Darko
authors.initials: D
authors.lastname: Makovec
authors.affiliation: Department of Biosciences, BioCity, Åbo Akademi University, BioCity, Artillerigatan 6, Åbo/Turku, SF-20520, Finland. hhagerst@abo.fi.
authors.forename: Henry
authors.initials: H
authors.lastname: Hägerstrand
authors.affiliation: Group of Nanobiology and Nanotoxicology, University of Ljubljana, Biotechnical Faculty, Večna pot 111, Ljubljana, SI-1000, Slovenia. damjana.drobne@bf.uni-lj.si.
authors.forename: Damjana
authors.initials: D
authors.lastname: Drobne
authors.affiliation: Laboratory of Clinical Biophysics, University of Ljubljana, Faculty of Health Sciences, Zdravstvena pot 5, Ljubljana, SI-1000, Slovenia. veronika.kralj-iglic@fe.uni-lj.si.
authors.forename: Veronika
authors.initials: V
authors.lastname: Kralj-Iglič
mesh_terms: D000328:Adult; D001773:Blood Cells / Q000187:drug effects; D001792:Blood Platelets / Q000187:drug effects*; D002021:Buffers; D002462:Cell Membrane / Q000187:drug effects*; D048430:Cell Shape / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D053260:Soot / Q000737:chemistry* / Q000494:pharmacology; D013535:Suspensions / Q000737:chemistry
chemical_list: D002021:Buffers; D010743:Phospholipids; D053260:Soot; D013535:Suspensions