RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY PHONG TIEN HUYNH SOLVENT-FREE BETA-CAROTENE NANOPARTICLES FOR FOOD FORTIFICATION New Brunswick, New Jersey October 2012 ABSTRACT OF THE DISSERTATION SOLVENT-FREE BETA-CAROTENE NANOPARTICLES FOR FOOD FORTIFICATION By PHONG TIEN HUYNH Dissertation director: Professor PAUL TAKHISTOV Most nutraceutical compounds are poorly-water soluble. Their low solubility decreases the adsorption rate in living organisms leading to their low bioavailability. Utilization of nanoparticles is a promising way to improve the solubility of hydrophobic compounds. Nanoparticles increase the total surface area of the poorly-water soluble nutraceuticals making them more bioavailable.
Some traditional methods for decreasing particle size include pearl or jet milling, where particles are broken down through grinding or collisions under high pressure. These mechanical processes not only require high energy input but also raise a concern of milling media residues. The high pressure homogenizer approach applies implosion forces and collision of particles to generate nanosuspensions. This method requires microsuspensions as starting material and consumes high energy.
ii Among several emulsion-based techniques for preparing nanoparticles, solvent diffusion practice is a novel approach in which a poorly-water soluble compound is transferred into nanoemulsion droplets of a partially water-soluble organic solvent. The compound then crystallizes because the solvent diffuses out of the emulsion droplets. The key point of proposed emulsion-diffusion technology is that the phase transition occurs within an isolated nanoemulsion droplet. The main purpose of this study is to develop a “green” and scalable method for preparing nanosuspensions of highly hydrophobic compounds.
We use FDA GRAS ingredients to create nanoparticles of poorly-water soluble nutraceuticals. β-carotene is selected as a model hydrophobic nutraceutical. Triacetin, a partially- water soluble triacetate compound, is used as the dispersed phase of nanoemulsions. The influence of surfactant, water concentration, and homogenization time on particle size and stability is investigated.
The impact of surfactant on diffusion flux of triacetin is studied. Kolmogorov theory is applied to reveal the breakup mechanism of emulsion droplets under shear and predict their size. A mathematical model is built to discover the size of emulsion droplet during the formation of nanosuspensions. It is hoped that the this work will greatly advance the manufacture of nanoparticles of poorly-water soluble nutraceuticals iii ACKNOWLEDGEMENTS I would like to thank my advisor professor Takhistov, for his guidance, unending support, and for exposing me to a broad range of studies including nutraceuticals, simulations and colloidal science.
In addition, I would like to thank him for always supporting my somewhat non-conventional ideas for side projects. I would also like to thank members of professor Takhistov’s group including: Marlena Brown, Abhishek Sahay, Maha Ashehab for their collaborations knowledge, and support throughout the years. In addition, I would like to thank Dr Changhoon Chai for advices and helps at beginning. I would like to thank Dr.
Khusid, Dr Yam, and Dr Karwe for their great suggestions and discussions. I would like acknowledge US government and Vietnamese government for their program to give me a chance to study in the United States of America. iv DEDICATION I dedicate this dissertation to my family who endlessly love and support me to make this work possible. v TABLE OF CONTENT ACKNOWLEDGEMENTS.
iv TABLE OF CONTENT. vi LIST OF TABLE. ix LIST OF FIGURES. Nanotechnology and nanoparticles in food.
Solid lipid nanoparticle (SLN. Nanostructure lipid carriers (NLC). Lipid drug conjugate (LDC). Co-acervate nanoparticles.
Smaller size better solubility of nutraceuticals. High pressure homogenization. Solvent – based method. Emulsion as template method.62 MATERIALS AND METHODS.
Beta-carotene (MW = 536. Spectrofotometer for defining the solubility of beta-carotene in triacetin. Optical goniometer for surface tension. Dynamic light scattering (DLS) technique for particle size and zeta potential84 2.
Differential scanning calorimetry. X-ray diffraction for characterizing crystallinity. Diffusing wave spectroscopy for nano-rheology of gels .94 PHYSICAL CHEMISTRY OF TRIACETIN – BETA CAROTENE SYSTEM. The formation of emulsion droplet in triacetin –water system.
Definition of emulsion. Formation of emulsion droplets. Droplet breakup mechanism. Droplet breakup mechanism in laminar flow.
Droplet breakup mechanism in turbulence flow. Impact of surfactant on emulsion droplet size. Impact of other factors to emulsion droplet size. The adsorption of surfactant on triacetin interface.
Solubility of beta-carotene in triacetin. Mathematic model for the diffusion of triacetin from an emulsion droplet. The crystallization of beta-carotene in emulsion droplet. The diffusion of triacetin from a droplet.
Impact of surfactant on the particle size. Impact of operation parameters on the particle size and stability of nanosuspension141 6. Shelf life of beta-carotene nanoparticles .144 CHARACTERIZATION OF BETA-CAROTENE NANO PARTICLES .150 EDIBLE FILM LOADED BETA-CAROTENE NANOPARTICLES: MODEL OF FOOD FORTIFICATION. Physical chemistry of aqueous hydroxypropyl methyl cellulose (HPMC) solution 156 3.
Film formation model. Factors impact the film formation. Nano-rheology of HPMC gels. Moisture adsorption of the films .183 viii LIST OF TABLE Table 1: Physicochemical and biopharmaceutical drug properties and food effect [20].
6 Table 2:Percentage of surface molecules for different particle sizes [68]. 12 Table 3: Sensitivity of some vitamins to the food matrix and environment factors. 38 Table 4: Comparative challenges for delivery nutraceuticals: in-food and in-vivo. 48 Table 5: The 10 foods having the highest beta-carotene content per serving.
65 Table 6: Biochemical functions of beta-carotene in humans. 67 Table 7: The HLB value of some chemical groups. 75 Table 8: The application of emulsifiers based on their HLB value. 76 Table 9: Dimensions of the lamellar[406].
79 Table 10 : Seven crystal systems. 92 Table 11: High shear mixer properties and maximum particle size for triacetin – lecithin system. 111 Table 12: The surface tension of triacetin – surfactant – water system and the maximum emulsion droplet size estimated by Kolmogorov theory. 112 Table 13: Adsorption parameters of surfactant -triacetin system.
117 Table 14: Molar factor of Triacetin. 125 Table 15: Distance among surfactant molecules adsorbed on triacetin surface. 138 Table 16: The sorption isotherm model confidence fit of the films. 178 ix LIST OF FIGURES Figure 1: Scale of the structural elements in food matrices.
4 Figure 2: Fators influencing the stability of vitamins in foods [59]. 11 Figure 3: Loading mechanisms for nanoparticulate delivery systems. 13 Figure 4: Schematic representations of modifications to the conventional liposome. 15 Figure 5: Schematic of methods for formation of two types of ionic hydrogels.
18 Figure 6: Schematics of micelle formation from amphiphilic unimers and drug incorporation by covalent binding or non covalent binding to the hydrophobic moiety [120] (Adapted from [121]). 21 Figure 7: Intestinal absorption pattern. 40 Figure 8: The collision of particles during peal milling. 50 Figure 9: Jet milling chamber (the dash - dotted represents the outlet stream; the curve arrow stands for the circular stream for particle separation; 𝜃 is the nozzle angle).
51 Figure 10: Particles break under high shear in high pressure homogenizer. 54 Figure 11: Morphology of particle prepared by spraying method [310]. 58 Figure 12 : Schematic procedure of preparation solid lipid nanoparticles [324]. 61 Figure 13 : The structure of chemicals used in the research.
64 Figure 14: Force acting on the molecules at interface and in the bulk. 72 Figure 15: The distribution of surfactant with different HLB values in oil – water mixture. 76 Figure 16: Lamellar structures of lecithin at interface. 78 Figure 17: Schematic of a spetrophotometer.
81 Figure 18 : Geometry of a pendant droplet. 83 Figure 19: The fluctuation of scattering light from particles in a liquid medium. 86 Figure 20 : Schematic diagram of heat flux differential scanning calorimetri cells. 89 Figure 21: A typical DSC thermogram of a material showing the glass transition Tg , recrystallization exotherm temperature Tc and enthalpy ΔH c , melting endotherm onset melting temperature, Tm0 , the extrapolation onset crystallization, Tme , the peak of melting temperature, 𝑇𝑚, and heat of fusion, ∆𝐻𝑚.
91 Figure 22: Unit cell. 92 Figure 23: X-ray diffraction on a crystal (left) and the schematic of an X-ray diffraction (right). 93 Figure 24: Schematic of DWS technique. 98 Figure 25: A typical Oil/Water emulsion system.
101 Figure 26: Physicochemical process of emulsification [417]. 103 Figure 27: The droplet breakup mechanism. 105 Figure 28: The streamlines of laminar flow field of equation (43) for 1 ≥ 𝛼 ≥ 0. 106 Figure 29: Emulsion droplet size versus surface tension.
111 x Figure 30 : Surface tension of lecithin and Tween 20 solutions. 117 Figure 31: Solubility of β-carotene in Triacetin Curve. 118 Figure 32: The diffusion of triacetin from an emulsion droplet. 119 Figure 33: The evolution of droplet radius over time.
124 Figure 34: The diffusion flux of triacetin from a pendant droplet. 126 Figure 35: Nucleation energy. 130 Figure 36 : The mass fraction of solid beta-carotene versus emulsion droplet size during the diffusion of triacetin. 133 Figure 37: Triacetin diffused from a pendant droplet.
134 Figure 38 : The flux of triacetin in different surfactant solutions. 135 Figure 39: Impact of surfactant on the particle size. 140 Figure 40: impact of homogenization time on particle size. 141 Figure 41: Particle size and zeta potential as function of water content and time.
144 Figure 42 : The impact of Oswald ripening on particle size distribution. 144 Figure 43: The evolution of particle size distribution during 4 days since they are created. 148 Figure 44: The shelf life of beta-carotene nanoparticles during long time storage. 149 Figure 45 : XRD spectra of pure beta – carotene and beta – carotene nanoparticles.
151 Figure 46: DSC thermograms of pure beta-carotene, lecithin, and beta-carotene nanoparticle. 151 Figure 47: Particle size distribution of beta-carotene nanoparticles before lyophilization and after lyophilization. 153 Figure 48: SEM image of the beta-carotene nanoparticles. 154 Figure 49: Structure of HPMC.
156 Figure 50: The polymer - surfactant interaction in aqueous media. 156 Figure 51: surface tension of lecithin - HPMC aqueous solution. 158 Figure 52: Model of water removal from the polymer solution during film formation 159 Figure 53: The distribution of polymer concentration in the film at different evaporation rate. 160 Figure 54: The evaporation flux of the films.
165 Figure 55 : Surface of the HPMC films under microscope. 165 Figure 56: Phase diagram of lecithin -water system.I means “viscous isotropic” phase; Tc represents the ill-defined boundary of crystal – to – liquid crystal phase transition; the cross-hatched region between 0 to 5% water from 45 to 900C stands for a poorly region where lamellar liquid crystalline phase may coexist with another liquid crystalline phase [406]. 166 Figure 57: Diagrammatic reconstruction of the bimolecular lecithin leaflet in relation to the amount of water present.