Radiation-induced formation of polyacrylic acid–protein covalent conjugates

Aggregation Behavior of Poly(Acrylic acid-co-Octadecyl Methacrylate) and Bovine Serum Albumin in Aqueous Solutions

Polymer-protein complexing systems have been extensively studied because of their wide application in biomedicine and industry. Here, we studied the aggregation behavior of the hydrophobically associating water-soluble polymer poly(acrylic acid-co-octadecyl methacrylate) [P(AA-co-OMA)] prepared with nonionic surfactant as an emulsifier and bovine serum albumin (BSA) in aqueous solution. We identified the optimal composite conditions of P(AA-co-OMA) and BSA aqueous solution. We measured the zeta potential, dynamic light-scattering particle size, and surface tension of P(AA-co-OMA) and BSA mixed aqueous solution. The results showed that the aggregation behavior between the polymer and BSA relied mainly on the hydrophobic interactions between the molecules. In addition, the best compounding condition was 8 wt.% of P(AA-co-OMA) content. The structure of hydrophobically associating polymer P(AA-co-OMA) and its aggregation with BSA were characterized by Fourier-transform infrared spectroscopy. The infrared spectroscopy results identified the hydrogen bonding behavior of the amino and carboxyl groups between the polymer and BSA. This behavior was also confirmed using thermogravimetric analysis and differential scanning calorimetry. The thermal decomposition temperature and melting temperature of BSA changed before and after it was combined with the polymer. We measured the morphology of the polymer BSA aggregate with 8 % polymer content by transmission electron microscopy. The binding mechanism was investigated, as well.

An In vivo study: Adjuvant activity of poly-n-vinyl-2-pyrrolidone-co-acrylic acid on immune responses against Melanoma synthetic peptide

Peptides have been studied as an important class of components in medicine to control many major diseases with vaccination. Polymers as adjuvants are capable of enhancing the vaccine potential against various diseases by improving the delivery of antigens, and they reduce the booster doses of vaccines. In brief, polymers are promising candidates for peptide-based vaccine delivery platforms. The purpose of the present study was to create a possible alternative approach in the treatment of malignant melanoma and/or to prevent metastasis of melanoma. The study was designed as both an experimental and an in vivo study. We prepared a complex and covalent conjugate of MAGE-3 121-134 (L-L-K-Y-R-A-R-E-P-V-T-K-A-E) T-cell epitope as a vaccine candidate for melanoma. These conjugates were able to generate an immune response in mice after a single immunization, without the help of any external adjuvant. The peptide-polymer complexes activated the immune system in the best way and formed the highest antigen specific immune response. These results indicate the adjuvant activity of Poly(N-vinyl-2- pyrrolidone-co-acrylic acid) [P(VP-co-AA)] and the potential use of P(VP-coAA)-peptide based vaccine prototypes for future melanoma cancer vaccine formulations.

The Fluorescence Study of Interaction Between Bovine Serum Albumin and Polyacrylic Acid

The complex formation of Bovine Serum Albumin (BSA) with anionic polyelectrolyte (polyacrylic acid, PAA) in aqueous solution was studied by a fluorescence technique, pH titration and HPLC analysis. The character of the interactions and solubility of the polycomplex particles depends on the BSA/PAA ratios and the pH of solution. The interaction at pH > pI (isoelectric point of BSA) (pH 6.0-7.0) is negligible weak and at pH 5.0 results with the formation of stable water-soluble polycomplexes at a wide range of protein/polymer ratios. The fluorescence intensity of BSA sharply decreased when an different amount of PAA was added and its maximum wavelength shifts towards the blue region. The protein molecules in the structure of soluble polycomplex particles are densely covered by the shelf of a polymer coil and practically "fenced off" from the water environment. This effect was reinforced by the increase of protein components. Existence of soluble and insoluble PAA-BSA complexes have been observed at pH < pI (pH 4.0-4.3). These soluble complexes characterized by the structure of particles in which protein molecules are densely covered by the shelf of a polymer coil. By the increase in the protein concentration, these complexes aggregate to an interpolymer species.