Search results

(1 - 2 of 2)
INCORPORATION OF INORGANIC AND ORGANIC ADDITIVES INTO MODEL PACKAGING POLYMERS
Title
INCORPORATION OF INORGANIC AND ORGANIC ADDITIVES INTO MODEL PACKAGING POLYMERS
Creator
Bajaj, Akhil
Date
2016, 2016-12
Description
Nowadays, various commercial polymers such as low density poly(ethylene) (LDPE), poly(propylene) (PP), and Nylon, may contain or are...
Show moreNowadays, various commercial polymers such as low density poly(ethylene) (LDPE), poly(propylene) (PP), and Nylon, may contain or are fabricated with molecular and/or nano-sized inorganic filler elements. These fillers elements often modify, enhance or bring desired changes to the native properties of these polymers. However, these additives also have the potential to interact with the physical environment. For any new additive, it is important to assess and evaluate the potential consumer exposure under intended conditions of use. This thesis reports on the preparation of model polymer samples fabricated with various molecular and nano-sized filler elements (exfoliated clays, quantum dots, and organic colorants) to help evaluate factors affecting the rate of migration and the potential consumer exposure associated with these materials. One of the main aims of this project is the development of methods to incorporate organic and inorganic additives into polymers relevant to food packaging and medical devices using a laboratory scale twin-screw micro-compounder. Some of the samples prepared via optimized methods include (1) 1, 3, 5, and 7 wt.% Montmorillonite in LDPE; (2) quantum dots (QDs) spanning a size range of 3-8 nm into LDPE; and (3) 1-2 wt.% colorant-loaded polymer films, where the colorants include phthalocyanine blue, phthalocyanine green, quinizarin blue, manganese (II) phthalocyanine and titanium (IV) oxide, and the host polymers include poly(propylene), poly(carbonate), Nylon 12, and PEBAX (poly(ether-block-amide)). In addition to optimizing methods for composite fabrication, the properties of these materials were analyzed using many techniques, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and Fourier transform-infrared (FT-IR) spectroscopy. Migration experiments were carried out to evaluate the interaction of samples with model food and environmental systems. This research was instrumental to support efforts to understand the mechanisms of potential exposure to polymer additives.
M.S. in Food Safety and Technology, December 2016
Show less
DEVELOPMENT OF FULLY BIOCOMPATIBLE HYDROGEL NANOPARTICLE FORMULATIONS FOR CONTROLLED-RELEASE DELIVERY OF A WIDE VARIETY OF BIOMOLECULES
Title
DEVELOPMENT OF FULLY BIOCOMPATIBLE HYDROGEL NANOPARTICLE FORMULATIONS FOR CONTROLLED-RELEASE DELIVERY OF A WIDE VARIETY OF BIOMOLECULES
Creator
Borges, Fernando Tancredo Pereira
Date
2020
Description
In recent years, our group has focused on the production of PEGDA-based hydrogel scaffolds and nanoparticles for drug delivery of small...
Show moreIn recent years, our group has focused on the production of PEGDA-based hydrogel scaffolds and nanoparticles for drug delivery of small molecules. However, with recent advances in modern therapeutic treatments, such as protein and genetic engineering, there is an increasing need for the development of drug delivery devices that would be able encapsulate larger molecules. Therefore, the goal of this thesis work was to develop a systematic way to produce fully biocompatible PEGDA-based hydrogel nanoparticle formulations that would be able to encapsulate any size molecule, ranging from small ionic molecules, to peptides and proteins, all the way to large nucleic acids, and deliver it in a controlled manner.The first of part of this work consisted of developing a stable and reproducible process for the production of hydrogel PPi-NPs. Initial studies were done in order to assess the influence of phosphate salts in the polymerization system and it was found that both monophosphate and polyphosphate salts significantly damper the NVP homo-polymerization kinetics, but do not affect the co-polymerization of NVP and PEGDA. Then, emulsion stability studies were done to determine whether phosphate salts affected the stability of the minimeulsion system used in the production of the nanoparticles. Cloud point measurements and droplet size screening measurements showed that by transitioning from a Pi-loaded emulsion system to a PPi-loaded emulsion system, the required HLB of the emulsion shifts by 1.5 points. Upon correction for that shift, a reproducible process for production of PPi-loaded nanoparticles was obtained. A parametric study was then performed to see how the different process parameters affected the different properties of the produced particles. The second part of the work consisted in developing a platform for encapsulation of large to very-large molecules within these hydrogel systems. A new set of equations was developed for better estimation of the interstitial space, available for encapsulation of molecules, of crosslinked polymers that used very high molecular weight crosslinkers and/or high amounts of crosslinker. Upon development of this new set of equations, hydrogel discs were made via photopolymerization in order to validate the equations. By introducing a third monomer, EGA, and varying the molecular weight and concentration of the crosslinker, hydrogels with a wide range of mesh dimensions from 25 to 700 were achieved. These gels were then used to encapsulate 4 different sample molecules of varying molecular weights and size. A new heuristic was developed for encapsulation of non-spherical molecules, where the aspect ratios of the molecule and of the polymer network are considered. By varying the size of the ratios of the dimensions of the hydrogel network to the dimensions of the molecule, significantly different release profiles of small molecules, peptides and oligonucleotides were obtained. Finally, in order to explore different administration routes, the process was transitioning into being fully biocompatible. The organic solvent previously used in the emulsion system was replaced by soybean oil and the surfactants were replaced by a food-grade surfactant, PGPR, to form Bio-Compatible Nanoparticle Emulsions (BCNEs). Qualitative release from the BCNEs was shown. A new method for quantitative measuring of release from BCNE was developed. Release from QK-BCNE was observed up to 46 days, which is unprecedented for sustained-release and revolutionary for the field. A BCNE spreadable ointment formulation was also developed.
Show less