title: Probing microbubble targeting with atomic force microscopy.
abstract: Microbubble science is expanding beyond ultrasound imaging applications to biological targeting and drug/gene delivery. The characteristics of molecular targeting should be tested by a measurement system that can assess targeting efficacy and strength. Atomic force microscopy (AFM) is capable of piconewton force resolution, and is reported to measure the strength of single hydrogen bonds. An in-house targeted microbubble modified using the biotin-avidin chemistry and the CD31 antibody was used to probe cultures of Sk-Hep1 hepatic endothelial cells. We report that the targeted microbubbles provide a single distribution of adhesion forces with a median of 93pN. This interaction is assigned to the CD31 antibody-antigen unbinding event. Information on the distances between the interaction forces was obtained and could be important for future microbubble fabrication. In conclusion, the capability of single microbubbles to target cell lines was shown to be feasible with AFM.
authors.affiliation: Medical Physics, School of Clinical Sciences and Community Health, University of Edinburgh, Edinburgh, UK. Vassilis.Sboros@ed.ac.uk
authors.forename: V
authors.initials: V
authors.lastname: Sboros
authors.forename: E
authors.initials: E
authors.lastname: Glynos
authors.forename: J A
authors.initials: JA
authors.lastname: Ross
authors.forename: C M
authors.initials: CM
authors.lastname: Moran
authors.forename: S D
authors.initials: SD
authors.lastname: Pye
authors.forename: M
authors.initials: M
authors.lastname: Butler
authors.forename: W N
authors.initials: WN
authors.lastname: McDicken
authors.forename: S B
authors.initials: SB
authors.lastname: Brown
authors.forename: V
authors.initials: V
authors.lastname: Koutsos
mesh_terms: D000906:Antibodies / Q000737:chemistry* / Q000276:immunology; D001360:Avidin / Q000737:chemistry*; D045744:Cell Line, Tumor; D003287:Contrast Media / Q000737:chemistry; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D045423:Microbubbles; D018625:Microscopy, Atomic Force / Q000379:methods*; D008856:Microscopy, Fluorescence; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000737:chemistry / Q000276:immunology
chemical_list: D000906:Antibodies; D003287:Contrast Media; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D001360:Avidin