Treatment Of VEGF Overexpression Via DNA Aptamer-Encapsulated Polymer Microneedle Arrays

Open Access
Davis, Brandon Joseph
Area of Honors:
Biomedical Engineering
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Yong Wang, Thesis Supervisor
  • Nanyin Zhang, Honors Advisor
  • William O Hancock, Faculty Reader
  • Protein Overexpression
  • DNA Aptamer
  • Polymer Microneedle
The overexpression of any protein could lead to a dramatic imbalance in the fragile homeostatic environment within the human body. Therefore, it is important to develop novel protein blockers to control the overexpressed proteins and drug delivery systems to deliver protein blockers. Nucleic acid aptamers are an emerging class of protein blockers with high binding specificity and affinity unrivaled by traditional antibodies. After binding to their target proteins, aptamers can inhibit the bioactivity of the proteins. The purpose of this thesis was to demonstrate that aptamer-functionalized microneedles can be applied to release aptamers to block the bioactivity of proteins using vascular endothelial growth factor (VEGF) and its aptamer as a model. Polymer microneedle arrays were fabricated by casting a 3:1 PVA/PVP over PDMS molds. Needle height and tip radius measurements determined from SEM images were verified using optical profilometry and brightfield imaging techniques. Surface plasmon resonance (SPR) was utilized to compute the dissociation constant (KD) of the anti-VEGF aptamer. Aptamer degradation in M200 + 0.5% FBS growth media was visually represented using gel electrophoresis. A dissolution trend was obtained by inserting polymer microneedle arrays into an agarose gel skin mimic for defined time intervals. Mechanical testing, performed on the Instron 5960, quantified the compressive failure force, indicated by a distinct change in the compressive load. Aptamer distribution was predicted using diffusion kinetics and tracked using a FAM-modified aptamer. An endothelial cell tube formation assay expressed the level of VEGF sequestration by aptamer. Total tube length, measured with ImageJ software, was used to quantify cell growth and angiogenesis inhibition. The application potential of biomaterial devices has intensified from the successful encapsulation of aptamer in polymer microneedle arrays. The aptamer displayed exceptional durability throughout the heat intensive fabrication process, withstanding conformational changes and functionality. Data suggests that this aptamer sequence can successfully sequester VEGF protein and inhibit tube formation, indicating the ability to disrupt angiogenesis.