Characterizing moisture uptake and plasticization effects of water on amorphous amylose starch models using molecular dynamics methods

Dynamics and thermophysical properties of amorphous starch were explored using molecular dynamics (MD) simulations. Using the OPLS3e force field, simulations of short amylose chains in water were performed to determine force field accuracy. Using well-tempered metadynamics, a free energy map of the two glycosidic angles of an amylose molecule was constructed and compared with other modern force fields. Good agreement of torsional sampling for both solvated and amorphous amylose starch models was observed. Using combined grand canonical Monte Carlo (GCMC)/MD simulations, a moisture sorption isotherm curve is predicted along with temperature dependence. Concentration-dependent activation energies for water transport agree quantitatively with previous experiments. Finally, the plasticization effect of moisture content on amorphous starch was investigated. Predicted glass transition temperature (T_g) depression as a function of moisture content is in line with experimental trends. Further, our calculations provide a value for the dry T_g for amorphous starch, a value which no experimental value is available.

Alkaline protease for an efficacious rehydration of skin matrix by a novel Bacillus crolab MTCC 5468 in sustainable leather production: a green approach

OBJECTIVES

The utilization of biotechnology in leather sector has more extensive in modern years; more particular to proteolytic enzymes and employed in several steps of the leather making such as soaking, dehairing, bating, solid waste management etc. The current study evaluates the performance of alkaline protease from Bacillus crolab MTCC 5468 in single soaking of goat skins matrix by comparing with the conventional multiple soaking processes.

RESULTS

According to the obtained results, the optimum concentration for maximum rehydration of goat skins was accomplished at 1.0% (v/w) of alkaline protease at duration of 3 h over traditional rehydration method (4-6 h). The moisture level, total protein, chloride content and total organic carbon of enzymatic rehydration was superior to that of conventional rehydration and it was also used to measure the effectiveness of rehydration process. Scanning electron microscopic images of enzymatically processed leather exhibits enhanced opening of fiber bundles and smooth grain surface than conventional method. Furthermore, the alkaline protease treated leather exhibited improved moisture uptake, removal of chlorides and suppleness because of hydrolysis of non-collagenous proteins as indicated by well opened up fiber bundles in histological analysis.

CONCLUSIONS

The application of alkaline protease in rehydration operation of leather production confirmed scope for diminishing water quantity around 66.6%, soaking duration at 50%, minimizing use of harmful dehairing chemicals at 50-60%, thereby, eliminating the bating operation during pre-tanning. These outcomes suggest that alkaline protease have potential application in rehydration of skins for immense environmental concerns of leather tanning sectors.

Characterization of methacrylated alginate and acrylic monomers as versatile SAPs

Superabsorbent polymers (SAPs) based on polysaccharides, especially alginate, could offer a valuable solution in a plethora of applications going from drug delivery to self-healing concrete. This has already been proven with both calcium alginate and methacrylated alginate combined with acrylic acid. In this manuscript, the effect of varying the degree of methacrylation and use of a combination of acrylic acid and acrylamide is investigated to explore the effects on the relevant SAP characteristics. The materials showed high gel fractions and a strong swelling capacity up to 630g_water/g_SAP, especially for superabsorbent polymers with a low degree of substitution. The SAPs also showed only a limited hydrolysis in aqueous and cement filtrate solutions.

Evaluation of excipients for enhanced thermal stabilization of a human type 5 adenoviral vector through spray drying

We have produced a thermally stable recombinant human type 5 adenoviral vector (AdHu5) through spray drying with three excipient formulations (l-leucine, lactose/trehalose and mannitol/dextran). Spray drying leads to immobilization of the viral vector which is believed to prevent viral protein unfolding, aggregation and inactivation. The spray dried powders were characterized by scanning electron microscopy, differential scanning calorimetry, Karl Fischer titrations, and X-ray diffraction to identify the effects of temperature and atmospheric moisture on the immobilizing matrix. Thermal stability of the viral vector was confirmed in vitro by infection of A549 lung epithelial cells. Mannitol/dextran powders showed the greatest improvement in thermal stability with almost no viral activity loss after storage at 20°C for 90days (0.7±0.3 log TCID50) which is a significant improvement over the current -80°C storage protocol. Furthermore, viral activity was retained over short term exposure (72h) to temperatures as high as 55°C. Conversely, all powders exhibited activity loss when subjected to moisture due to amplified molecular motion of the matrix. Overall, a straightforward method ideal for the production of thermally stable vaccines has been demonstrated through spray drying AdHu5 with a blend of mannitol and dextran and storing the powder under low humidity conditions.

Characterization of soluble soybean polysaccharide film incorporated essential oil intended for food packaging

This study examines the development of new bio-active polysaccharide-based bioplastics through casting and solvent-evaporation. Soluble soybean polysaccharide (SSPS) films incorporated with Zataria multiflora Boiss (ZEO) or Mentha pulegium (MEO) at various concentrations were prepared and characterized. The presence of ZEO and MEO improved polysaccharide interactions, reducing the films' water solubility and water vapor barrier properties, but did not markedly modify their moisture content or thickness. Differing amounts of ZEO or MEO had no significant effect on mechanical behavior, with the exception of 3% oil concentration, which decreased tensile strength and significantly increased elongation at break. DMTA curves revealed a single Tg, which may indicate the compatibility of essential oil and SSPS. The electron scanning micrograph for the composite film was homogeneous, without signs of phase separation between the components. These results suggest that ZEO and MEO can potentially be directly incorporated into SSPS to prepare active biodegradable films for food-packaging applications.