Synthesis and Characterization of Multi-Functional Nanoparticles for Therapeutic and Biosensing Applications

Abstract

In this research, a variety of nanosized polymeric derivatives, particularly for applications in drug delivery systems and enzyme nanocarriers, were synthesized and characterized. Most of the nanocarriers were formulated with a matrix consisting of poly(DL-lactic acid-co-glycolic acid) (PLGA) or poly(ethylene glycol)-PLGA and stabilized by polyvinyl alcohol (PVA) or Pluronic F-68 for the encapsulation of an insulin derivative, a model therapeutic enzyme, and anticancer drugs. The protein hormone release from biodegradable nanoparticles prepared using double emulsion solvent evaporation was quantified and release phases were identified. Insulin-like growth factor (IGF1)-loaded nanoparticles showed that the released protein was able to stimulate an important pathway for effective cell proliferation and cell survival. Several excipients that helped increase encapsulation efficiency of IGF1 were used, particularly, bovine serum albumin (BSA), poly(propylene glycol), and a triblock polymer combining poly(propylene glycol) and poly(ethylene glycol) — materials that act as adsorption enhancers of the protein in the PLGA nanoparticle. The proteolytic enzyme, trypsin, was encapsulated in PLGA nanoparticles and its behavior during the encapsulation process and release represented the characteristics of most enzymatic systems. Experimental kinetic experiments towards a synthetic substrate studied the activity of trypsin during encapsulation and after its release. The nanoparticle encapsulated enzyme maintained significant enzymatic activity and after its release, a good amount of the activity was evident from the kinetic work. Its proteolytic activity was also unmistakable since the free enzyme released from the nanoparticle lost significant activity within four hours after its release. PEGylation of the protein was also considered in this study and was encapsulated as well. However, the determination of the conjugate enzymatic activity was challenging since the PEG-enzyme complex had only 10% of the corresponding enzymatic activity; as a consequence, the determination of the PEG-enzyme complex after encapsulation and release was difficult to accomplish with rigorous precision. Another phase of this work involved the nanoparticle encapsulation of two anticancer drugs used as therapeutic agents in non-smokers lung cancer — erlotinib (Tarceva/OSI-420) and osimertinib (Tagrisso/AZD9291). The encapsulation was performed by single emulsion solvent evaporation and nanoprecipitation. The encapsulation efficiency of OSI-420 increased using the nanoprecipitation method while that of AZD9291 was increased using the single emulsion solvent evaporation method. Preliminary encapsulated OSI-420 and AZD9291 did not show significant difference in effectiveness compared with the free drugs in vitro. This effect was probably the results of low encapsulation efficiency of the drug in the PLGA nanoparticles. In addition, fluorescent, polystyrene submicron particles were utilized to detect and quantify two different cancer markers — carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9) from diluted whole blood or undiluted serum, on a paper-based microfluidic platform. These particles were covalently conjugated with anti-CEA and anti-CA 19-9 antibodies and stabilized with BSA. Immunoagglutination of the antibody-conjugated particles in the presence of either CEA or CA 19-9 changed the fluorescent scatter signals (440 nm blue and 660 nm red) upon 365 nm UV excitation. The use of UV excitation and subsequent fluorescence scattering enabled much higher double-normalized intensities compared with elastic Mie scattering, successful detection in the presence of blood or serum, as well as distinct multiplex assays with minimum cross reaction of antibodies.