Extractable proteins from irradiated field natural rubber latex

Adsorption of extracellular polymeric substances from two microbes by TiO2 nanoparticles

Extracellular polymeric substance (EPS) secreted by microbes can interact with nanoparticles (NPs) and thus influence environmental behavior and toxicity of NPs. The adsorption of EPSs from two species of microbes (Escherichia coli and Chlorella pyrenoidosa) by four types of titanium dioxide nanoparticles (nTiO₂) (5, 10, and 40 nm anatase nTiO₂ and 25 nm rutile nTiO₂) were therefore specifically investigated. Results show that the adsorption kinetics and thermodynamics were dependent on sources and chemical properties of EPSs. EPS (20 mg C/L) from Escherichia coli mainly composed of protein (86%) with relatively higher molecular weight and aromaticity and more active functional groups (i.e., NH and -COOH) was effectively removed (>90%) by adsorption on nTiO₂ (100 mg and more), while much less (<40%) EPS from Chlorella pyrenoidosa with a main component of polysaccharide (68%) was adsorptively removed. The Fourier transform ion cyclotron resonance mass spectrometry analysis revealed the selective adsorption of aromatic components of EPSs by nTiO₂. The EPS adsorption capacity of nTiO₂ linearly increased with the specific surface area of the NPs. The rutile nTiO₂ with the smallest specific surface area had the highest EPS adsorption per unit surface area. These findings promote a deeper understanding of the interaction between EPS and NPs.

REMOVING EXTRACTABLE PROTEINS IN NATURAL RUBBER LATEX BY CALCIUM CHLORIDE FROM CHICKEN EGGSHELLS

Controlling the level of the extractable protein contents in a natural rubber latex is important to the sensitization of natural rubber latex products users. Allergies caused by latex products cause a serious problem in which the sweat removes proteins and allowing a skin contact causing allergic reactions. Calcium oxide from calcined chicken eggshells at 900 °C for 1 h was dissolved in 2M HCl (CaCl2) and used as the thickening agent in which it can modify the protein structure. The eggshells were characterized by the particle size analysis, the impedance analysis, simultaneous thermal analysis (STA), x-ray diffraction (XRD), and Fourier transform infrared spectra (FTIR). Calcium chloride (CaCl2) interacts with the protein molecules and the solvent ions through the hydrogen bonding and the electrostatic interactions driving the extractable protein toward the film surface. Sodium dodecyl sulphate was used as the stabilizer in the natural rubber latex film formation. The extractable protein contents were measured and determined by the modified Lowry method. The concentrated latex samples were further characterized by FTIR, scanning electron microscope, and XRD and the results were reported here. Moreover, near infrared was used to measure the extractable protein spectra of the concentrated latex compounds in the region of 1100–2500 nm.