THE CALCIUM PHOSPHATE COATING OF SOY LECITHIN NANOEMULSION WITH PERFORMANCE IN STABILITY AND AS AN OXYGEN CARRIER by Kyu B. Han A dissertation submitted to the faculty of The University of Utah in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Materials Science and Engineering The University of Utah May 2015 Copyright © Kyu B. Han 2015 All Rights Reserved The University of Utah Graduate School STATEMENT OF DISSERTATION APPROVAL The dissertation of Kyu B. Han has been approved by the following supervisory committee members: Agnes Ostafin , Chair 1 1 /2 4 /2 0 1 4 Date Approved Reaz Chaudhuri , Member 1 1 /2 4 /2 0 1 4 Date Approved Ling Zang , Member 1 1 /2 4 /2 0 1 4 Date Approved Ashutosh Tiwari , Member 1 1 /2 4 /2 0 1 4 Date Approved Michael Granger , Member 1 1 /2 4 /2 0 1 4 Date Approved and by Feng Liu , Chair/Dean of the Department/College/School of _____ Materials Science and Engineering and by David B. Kieda, Dean of The Graduate School. ABSTRACT This work studied the relationship between surfactant, oil, and water, by building ternary phase diagrams, the goal of which was to identify the oil-in-water phase composition. The resulting nano-sized emulsion was coated with dicalcium phosphate by utilizing the ionic affinity between calcium ions and the emulsion surface. Since the desired function of the particle is as an oxygen carrier, the particle stability, oxygen capacity, and oxygen release rate were investigated. The first step in the process was to construct ternary phase diagrams with l,2-dioleoyl-sn-glycero-3-phosphate (DOPA) and soy derived lecithin. The results showed that the lecithin surfactant formed an oil-in-water phase region that was 36 times greater than that of DOPA. With the desired phase composition set, the lecithin emulsion was extruded, resulting in a well-dispersed nanosized particle. A pH titration study of the emulsion found an optimized calcium phosphate coating condition at pH 8.8, at which, the calcium ion had a greater affinity for the emulsion surface than phosphate. A Hill plot was used to show calcium cooperativeness on the emulsion surface which suggested one calcium ion binds to one lecithin molecule. The lecithin emulsion particles were then coated with calcium phosphate using a layering technique that allowed for careful control of the coating thickness. The overall particle hydrodynamic radius was consistent with the growth of the calcium phosphate coating, from 8 nm to 28 nm. This observation was further supported with cryo-TEM measurements. The stability of the coated emulsion was tested in conditions that simulate practical thermal, physical, and time-dependent conditions. Throughout the tests, the coated emulsion exhibited a constant mono-dispersed particle size, while the uncoated emulsion size fluctuated greatly and exhibited increased polydispersion. The fast mixing method with the stopped-flow apparatus was employed to test the product as an oxygen carrier, and it was shown that particles with thicker calcium phosphate coatings released smaller amounts of oxygen in a given timeframe. This study proved the hypothesis by showing a fundamental understanding of emulsion science, coating the flexible emulsion surface with a biocompatible material, and a strong particle performance with regard to stability and as an oxygen carrier. i'v TABLE OF CONTENTS ABSTRACT............................................................................................................................ iii LIST OF TABLES..................................................................................................................ix LIST OF FIGURES.................................................................................................................x ACKNOWLEDGEMENTS.................................................................................................xiv Chapters 1 INTRODUCTION............................................................................................................ 1 1.1 Overview................................................................................................................ 1 1.2 Background of Oxygen Carrier as a Blood Substitute.......................................2 1.2.1 Hemoglobin-based Oxygen Carrier (HbOC)............................................... 2 1.2.2 Perfluorocarbon-based Oxygen Carrier (PFBOC) ......................................3 1.3 Development of a Ternary Phase Diagram for Oil/Water/Surfactant...............5 1.3.1 Significance of Developing the Ternary Phase Diagram........................... 5 1.3.2 Perfluorocarbon-based Oxygen Carrier (PFBOC) ......................................6 1.3.2.1 Phase R ule................................................................................................6 1.3.2.2 Winsor System ........................................................................................ 7 1.3.3 Review Formulation for Oil-in-water Emulsion.........................................8 1.3.3.1 Micelle .....................................................................................................8 1.3.3.2 Microemulsion ........................................................................................ 8 1.3.3.3 Influence of Charged Surfactant on the Formulation .......................... 9 1.3.3.4 Instability of the Emulsion................................................................... 10 1.3.4 Technical Challenges of Constructing the Ternary Phase Diagram ....... 11 1.3.4.1 Current Methods for Constructing Ternary Phase Diagrams ........... 11 1.3.4.1.1 Visual Inspection ............................................................................ 11 1.3.4.1.2 Shear Stress and Strain................................................................... 12 1.3.4.1.3 Transmission Electron Microscopy (TEM) .................................. 12 1.3.4.2 Potential Methods for Constructing Ternary Phase Diagram ........... 13 1.3.4.2.1 Buoyant Density.............................................................................. 13 1.3.4.2.2 Fluorescence Quenching................................................................. 14 1.3.4.2.3 Fourier Transform Infrared Spectroscopy (FT-IR)...................... 15 1.4 Sizing of the Oil-in-water Emulsion................................................................. 17 1.4.1 Manufacturing Challenge for Emulsion......................................................17 1.4.2 Theory of Extrusion..................................................................................... 20 1.5 Design of Surface Coating on the Emulsion Particle.......................................21 1.5.1 Significance of the Surface Coating............................................................21 1.5.2 Review of Current Surface Coating on Nanoparticles.............................. 22 1.5.2.1 Properties of Silica as a Surface Coating............................................. 22 1.5.2.2 Properties of Polymer as a Surface Coating.........................................22 1.5.2.3 Surface Coating for the Emulsion using Silica and Polymers........... 23 1.5.3 Coating Material and Principles in This W ork..........................................23 1.5.3.1 Significance of Calcium Phosphate as the Coating Material..............23 1.5.3.2 Dicalcium Phosphate for the Surface Coating Material......................24 1.5.3.3 Technical Concepts for Surface Coating.............................................. 24 1.5.3.3.1 Surface Charge of Oil-in-water Emulsion Particle....................... 24 1.5.3.3.2 Calcium Selective Electrode for the Emulsion Surface Coating .. 25 1.5.3.3.3 Binding Coefficient for the Emulsion Surface Coating................26 1.5.3.3.4 Tangential Flow Filtration (TFF) for Concentration.....................27 1.6 Design of the Oxygen Release Measurement from Nanoparticle...................28 1.6.1 Significance of the Fast Mixing Method for Oxygen Determination...... 28 1.6.2 Oxygen Measurement in This Work...........................................................28 1.6.2.1 Significance of Usage of Hemoglobin................................................. 28 1.6.2.2 Chemical Reaction and Kinetics of Hemoglobin with Oxygen......... 28 1.6.2.3 Technical Concepts in This Work.........................................................31 1.6.2.3.1 Transport Phenomena of Drug Release with Hixson-Crowell Equation......................................................................................... 24 1.6.2.3.2 Measurement of Deoxygenated Hemoglobin by Clark Type Electrode........................................................................................ 25 1.6.2.3.3 Stopped-flow Apparatus and Dead Time for Hemoglobin Reaction.......................................................................................... 26 1.6.2.3.4 Relationship from Transmittance to Absorbance.......................... 27 1.7 The Work in This Dissertation...........................................................................28 2 DEVELOPMENT OF TERNARY PHASE DIAGRAMS FOR THE OIL-IN-WATER PHASE: DOPA/PFOB/WATER AND SOY LECITHIN/PFOB/WATER..............45 2.1 Abstract................................................................................................................45 2.2 Introduction......................................................................................................... 46 2.3 Materials and Methods....................................................................................... 48 2.3.1