Studies on Poly(Dialkoxyphosphazenes) for the Medical Applications

Abstract

The presence of trace of chlorine in poly(diorganophosphazenes) [-N=P(OR)2-]., where R = C₂H₅, CH₂CF₃, C₂F₅, C₄H₅, C₆H₁₃, C₈H₁₇, C₁₂H₂₅, CH₂C₆H₅ in many cases leads to the substantial changes of their physicochemical properties and limits application possibilities of this class of polymers especial for the medical materials. Despite the optimization of reaction conditions for each nucleophilic alkoxy substituent, the obtained poly(dia1koxyphosphaenes) exhibited some physicochemical anomalies.     

Thiophilic interaction chromatography of serum albumins

An investigation of the binding of native and recombinant human serum albumin and bovine serum albumin on three thiophilic gels, PyS, 2S, and 3S was performed. In addition to these proteins, we studied serum albumins from several species such as goat, rabbit, guinea pig, rat, hamster, baboon, and pig. Our results reveal that recombinant human serum albumin (rHSA) binds completely to PyS whereas native human serum albumin and bovine serum albumin bind only partially to PyS. The binding affinities of rHSA, human serum albumin and bovine serum albumin to 2S and 3S gels are less than their binding to PyS. Serum albumins from goat, rabbit, guinea pig, rat, hamster, baboon, and pig bind much stronger to 3S gel than human and bovine serum albumins. The binding of pig and hamster serum albumins is stronger than that of rat, goat, baboon, and rabbit.     

Heat capacity and thermopower coefficient of the carbon preform of sapele wood

This paper reports on measurements of the heat capacity at constant pressure C _p in the 80–300-K temperature interval and the thermopower coefficient S at 5–300 K of the carbon preform of sapele wood, which was prepared at the carbonization temperature of 1000°C. Measurements of C _p (T), our previous data on the phonon thermal conductivity, and literature information on the sound velocity have been used to calculate the phonon mean free path l(T) for this material. It has been shown that within the temperature interval 200–300 K, l is constant and equal to 11 Å, a figure matching the size of the nanocrystallites (“graphite fragments”) making up the carbon framework of the sapele carbon preform. The high-temperature parts of S(T) have been found to follow a linear course characteristic of diffusive thermopower for the degenerate state of charge carriers, with only one type of charge carriers present. The anisotropy of the thermopower coefficient has been estimated.     

Evaluation of the interaction of protein alpha-amino groups with M(II) by immobilized metal ion affinity chromatography.

The adsorption properties of various peptides and proteins, lacking histidyl groups, on immobilized Cu(II), Ni(II), Zn(II) and Co(II) ions are described; at pH 6 and below they were little retarded. At higher pH the retention became pronounced for iminodiacetate (IDA)-Cu(II) gel. This effect seems to be related to the presence of a terminal alpha-amino group; in the absence of this group the retention of the protein was largely eliminated. At pH 8.5 a terminal alpha-amino group is adsorbed as strongly as a histidyl group. IDA-Ni(II), IDA-Zn(II) and IDA-Co(II) gels display little or no attraction for the terminal alpha-amino group of a protein.     

Thiophilic interaction chromatography of human transferrins

Lactoferrin and serum transferrin, the iron-binding proteins, are widely distributed in biological fluids. Transferrins have many biological functions: anti-bacterial, anti-inflammatory, and immunoregulatory. A facile monitoring of the concentration of transferrins in biological fluids may have medical relevance. Thiophilic-interaction chromatography of transferrins may provide an efficient means for their quantitation in serum.     

Altered membrane amino acids composition in human colorectal cancer tissue

Cancer transformation is characterized by changes in cell metabolism, which can alter the structure and function of cell membrane components, including integral membrane proteins. Qualitative and quantitative estimations of integral membrane protein are necessary for studies aimed at understanding their modifications under pathological conditions.     

Factors Controlling Leaching of Polycyclic Aromatic Hydrocarbons from Petroleum Source Rock Using Nonionic Surfactant

The extraction of polycyclic aromatic hydrocarbons (PAHs) from petroleum source rock by nonionic surfactants with the assistance of microwave irradiation was investigated and the conditions for maximum yield were determined. The results showed that the extraction temperatures and type of surfactant have significant effects on extraction yields of PAHs. Factors such as surfactant concentration, irradiation power, sample/solvent ratio and mixing surfactants (i.e., mixture of surfactant at specific ratio) also influence the extraction efficiencies for these compounds. The optimum temperature for microwave-assisted nonionic surfactant extraction of PAHs from petroleum source rock was 120 °C and the best suited surfactant was Brij 35. The new method showed extraction efficiencies comparable to those afforded by the Soxhlet extraction method, but a reduction of the extraction times and environmentally friendliness of the new nonionic surfactant extraction system are clear advantages. The results also show that microwave-assisted nonionic surfactant extraction is a good and efficient green analytical preparatory technique for geochemical evaluation of petroleum source rock.

     

Thermopower of biomorphic silicon carbide

The thermopower coefficients of cubic bio-SiC, a high-porosity semiconductor with cellular pores prepared from the biocarbon template of white eucalyptus wood, and single-crystal β-SiC taken as a reference are measured in the temperature range 5–280 K. It is revealed that, in the low-temperature range, the samples are characterized by a thermopower contribution associated with the electron drag by phonons. The thermopower of the bio-SiC samples is measured both along and across the empty pore channels and is found to be anisotropic. Two models are proposed to account for the anisotropy of the thermopower in cubic bio-SiC.     

Immobilized metal ion affinity chromatography of proteins on IDA-Fe3+

Several proteins, selected for their varied isoelectric points within pH range ca. 4 to ca. ll, bind to immobilized (chelated to iminodiacetate) ferric ion, IDA-Fe³⁺, when applied in a 50 mM buffer, pH 6.0. These proteins can be displaced from IDA-Fe³⁺ columns by an increase of pH from 6 to 8, an increase of sodium chloride from 0 to 1 Malar and, in particular, by both. Apotransferrins, in contrast to other proteins, are able to scavenge Fe³⁺ ion from IDA-Fe³⁺. Interestingly, two proteins, both quite acidic, behave quite differently on IDA-Fe³⁺: α₁-acid glycoprotein (sialic acid) does not bind, whereas phosvitin (phosphate 1) binds avidly. IDA-Fe³⁺ sorbent, due to its unusual sorptive properties, represents a new addition of particular significance to the family of chromatographic sorbents available for protein purification.