Development of angiotensin (II) imprinted nanoparticles

Angiotensin II (Ang II) is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin-angiotensin system that regulates blood pressure. The role of Ang II on cardiovascular balance is quite large. Due to its relationship with scientifically proven cardiovascular diseases, it is an important biomarker in blood serum for the detection of diseases. Molecularly imprinted polymers (MIPs) are affinity-based polymeric support materials that enable the recognition of a specific target molecule with high selectivity. Molecular imprinting method is a very frequently used reliable technique to quickly and with high selectivity recognize the desired molecule (eg protein, amino acid, peptide, ion, etc.) from a complex environment. Within the scope of this thesis, Ang II imprinted nanoparticles were synthesized by miniemulsion polymerization reaction for the determination of Ang II from aqueous solutions. For the preparation of hydroxyethyl methacrylate (HEMA) based nanoparticles (NPs), a binary phase mixture was prepared. After Ang II imprinted (Ang II-MIPnp) and non-imprinted nanoparticles (NIPnp) were synthesized, they were characterized by Zeta Size analysis, Scanning Electron microscopy (SEM), Transmission Electron Microscopy (TEM) and FTIR-ATR spectrophotometer. Specific surface areas were then calculated. The average particle size of the NPs was recorded as 50 nm. The specific surface areas of Ang II-MIPnp and NIPnp were calculated as 26903.4 and 25868.9 m2/g, respectively. Ang II molecules were successfully removed from the polymeric structure with a 98% success rate using 0.5 M NaCl solution to obtain template-specific cavities in Ang II-MIPnp. Then, the adsorption of Ang II molecules from their aqueous solutions was investigated in terms of their binding capacity to the recognition sites. It has been found that the Ang II adsorption of NPs can go down to 50 pg/mL sensitively. 0.5 M NaCl solution was used for desorption and 98% recovery was achieved. The adsorption-desorption cycle was repeated 10 times and no significant change was observed in the adsorption capacity. The selectivity of NPs was evaluated in the presence of Angiotensin I (Ang I) and Vasopressin (Vsp), which are competitive molecules similar to Ang II in terms of molecular structure, shape and size. The results show that Ang II-MIPnp have high selectivity and sensitivity for Ang II molecule and shows that the synthesized nanomaterial is reusable. Keywords: Angiotensin II, Nanoparticles, Molecular imprinted polymers, Renin-Angiotensin-Aldosterone system (RAAS).