In this study we present detailed characterization of a protein-PEG conjugate using two separation techniques, that is, asymmetrical-flow field-flow fractionation (AF4) and size-exclusion chromatography (SEC), which were onlinecoupled to a series of successively connected detectors: an ultraviolet,a multiangle light-scattering, a quasi-elastic light-scattering, and a refractive-index detector (UV-MALS(QELS)-RI). Matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used as a complementary characterization technique. The results of AF4 as well as SEC on two columns connected in series, with both separation techniques coupled to a multidetection system, indicate the uniform molar massand chemical composition of the conjugate, that is, the molar ratio of protein to PEG is 1/1, the presence of minute amounts of residual unreacted protein and the aggregates with the same chemical composition as that of the conjugate. Since the portion of aggregated species is smaller in the acetate buffer solution containing 5% sorbitol than in the acetate buffer solution with 200-mM sodium chloride, the former buffer solution is more suitable for conjugate storage. The separation using only one SEC column results in poorly resolved peaks of the PEGylated protein conjugate and the aggregates, whereas MALDI-TOF MS analysis reveal the presence of the residual protein, but not the aggregates.
COBISS.SI-ID: 5034522
Due to their highly branched structure and the large number of functional groups hyperbranched polymers possess unique properties that make them interesting for uses in a wide variety of applications. Some of the most widely investigated hyperbranched polymers are the polyesters based on 2,2-bis(methylol)propionic acid. In this paper we present the results of characterization studies of hyperbranched polyesters based on 2,2-bis(methylol)propionic acid which show that they are very complex products with a multidimensional distribution of various properties. The influence of the synthesis conditions on the structure and molar-mass characteristics of hyperbranched polyesters as well as the findings that allow a thorough understanding of the structure-property relationships are reviewed in detail.
COBISS.SI-ID: 4487194
In this manuscript we have designed a synthetic approach for the preparation of a series of chitosan-graft-poly(L-glutamate) copolymers with different lengths of poly(L-glutamate) grafts. First, organosulfonic chitosan salt, soluble in DMSO, was prepared in order to effectively initiate ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride.The chitosan-graft-poly(γ-benzyl-L-glutamate) copolymers were fully deprotected by applying tetrabutylammonium hydroxide. The molar mass characteristics and the chemical composition of graft copolymers with various lengths of polypeptide grafts were determined by SEC-MALS, FT-IR and various NMR spectroscopic techniques. The synthesized copolymers were further used in combination with trimethyl chitosan for the preparation of nanoparticles (NPs) of a recombinant granulocyte colonystimulating factor (GCSF). The suspensions of NPs with typical average diameter of 200–300 nm were obtained with polydispersity index values below 0.26. The achieved loading efficiency was up to 95% and the final loading of GCSF protein in NPs was up to 45%. The time, temperature and pH stability of NPs was also studied.
COBISS.SI-ID: 5522714
High energy ultrasound was utilized for liquefaction of different lignocellulosic materials, wood wastes in particular. We developed a highly efficient way of transforming the biomass waste into the valuable chemicals. It was found, that reaction yield in all experiments was high and that reaction times were shortened up to nine times when using the ultrasound process with smaller residual particles and with no influence on the hydroxyl number of the final products. The use of ultrasound process inhibits the formation of large molecular structures from the degradation products during liquefaction by keeping the reactive segments apart and due to such a short reaction time being used. The short reaction time and subsequent low energy consumption for the liquefaction reaction leads to creation of the new method for transformation of wood waste materials into valuable chemicals.
COBISS.SI-ID: 1964681
Zinc(II) oxide nanoparticles were used for the stabilization of dicyclopentadiene (DCPD) −water-based high internal phase emulsions (HIPEs), which were subsequently cured using ring-opening metathesis polymerization (ROMP). The morphology of the resulting ZnO-pDCPD nanocomposite foams was investigated in correlation to the nanoparticle loading and nanoparticle surface chemistry. While hydrophilic ZnO nanoparticles were found to be unsuitable for stabilizing the HIPE, oleic acid coated, yet hydrophobic ZnO nanoparticles were effective HIPE stabilizers, yielding polymer foams with ZnO nanoparticles located predominately at their surface. These inorganic/organic hybrid foam-materials were subsequently calcined at 550 °C for 15 min to obtain inorganic macroporous ZnO foams with a morphology reminiscent to the original hybrid foam, and a specific surface area of 1.5 m2 g-1. Longer calcination time (550 °C, 15 h) resulted in a sea urchin like morphology of the ZnO foams, characterized by higher specific surface area of 5.5 m2 g-1. The latter foam type showed an appealing catalytic performance in the catalytic wet air oxidation (CWAO) process for the destruction of bisphenol A.
COBISS.SI-ID: 5593626