Poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic Acid) Nanogels made by Inverse Microemulsion Polymerization

Poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid) poly(AM-co-AMPSA) nanogels were prepared through inverse microemulsion polymerization with low AMPSA/AM weight ratio in the feed (up to 0.3357) to control particle size and pH sensitivity. An aqueous solution of AM and AMPSA was used as the dispersed phase for microemulsion with sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/Toluene solution as the dispersion medium. The polymerization was carried out at 50°C in the presence of 2,2-azobisisobutyronitrile (AIBN) and N,N′-methylenebisacrylamide (NMBA) as an initiator and a crosslinker, respectively. Fourier transform infra red spectrophotometer (FTIR) and ¹H-nuclear magnetic resonance spectroscopy (¹H-NMR) studies confirm the occurrence of copolymerization between the two monomers. The hydrodynamic diameter of synthesized poly(AM-co-AMPSA) nanogels is found to be in the range of 63–125nm as measured by dynamic light scattering (DLS). The equilibrium swelling and the effect of pH on particle size of copolymer nanogel are found to depend on the copolymer composition. The polymer chain composition, thermal properties and morphology of nanogels were measured by elemental analysis, thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC), and scanning electron microscope (SEM), respectively.     

Purification of ß-glucosidases from <Emphasis Type="Italic">Pichia etchellsii</Emphasis> Using CIM Monolith Columns

β-Glucosidases (EC 3.2.1.21) are industrially important glycosyl hydrolases used for cellulose saccharification as well as for synthesis of glyco-conjugates. Crystal structure of only one β-glucosidase of family 3 of the glycosyl hydrolase families is available due to difficulty in purification of these closely related enzymes from a given source. Multiple steps used during purification result in low yield, making it difficult to study their properties. Conditions for purification of two closely related β-glucosidases (BGL I and BGL II) of family 3 from Pichia etchellsii were investigated in this study. Two weak anion exchange columns convective interaction media-diethyl amino ethyl (CIM-DEAE) and CIM-ethylenediamine (CIM-EDA) were used for this purpose. The results obtained at 0.34 ml disk (CIM-DEAE) level were scaled up to 8 ml CIM-DEAE tube column wherein BGL I and BGL II were separated from the major contaminants in the cell-free extract. The recovered enzymes were completely resolved in the second step using CIM-EDA. A final specific activity of 9,180 IU/mg and 2,345.3 IU/mg was achieved for BGL I and BGL II respectively with an overall yield of 33%. The system should be applicable to resolution of other closely related enzymes from this family.