PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL Volume 6, Number 1, 2020
passing the paper through a bath of concentrated sulfuric acid, followed by rinsing out the acid and drying the sheet. Though both parchmentized paper and highly refined greaseproof paper products are still made, they have been substantially displaced by oil- repellent fluorocarbon treatments of paper. The fluorocarbon treatments have allowed papermakers to achieve greaseproof properties with ordinary paper machine equipment at ordinary refining levels and without a need to immerse the paper in strong acid. Now, however, due to environmental concerns and regulations, the paper industry needs more options. Some promising directions in published research include advances in chemistry, superoleophobic surfaces, nanocellulose films, and systems to protect nanocellulose films from the effects of moisture. Magnetic paper from sugarcane bagasse fibers modified with cobalt ferrite nanoparticles, Oscar H. Piñeres et al, Cellulose, Vol.27 . Magnetic paper sheets were prepared from bleached sugarcane bagasse fibers and cobalt ferrite nanoparticles by lumen loading method. Sugarcane bagasse is an important fibrous raw material widely used worldwide for papermaking, whereas cobalt ferrite nanoparticles is an appropriate material for fibers modification given their magnetic properties. Cobalt ferrite nanoparticles were synthetized by coprecipitation method and coated with silica by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) molecules. Then, silica coated magnetic nanoparticles were functionalized with polyethylenimine (PEI), as retention aid, by electrostatic bonding. It was observed that the loading degree of magnetic fibers depends on nanoparticles concentration and PEI dosage, which was determined by thermogravimetric analysis (TGA). Scanning electron microscope (SEM) shows the deposition of coated nanoparticles on the surface and into macropores of fibers. All samples exhibited ferromagnetic behavior. The coercivity values of magnetic fibers are higher than 0.2 kOe. This indicates that these fibers could be used to produce paper for magnetic recording purposes. Magnetic papers with 10 and 20% of modified fibers were manufactured. Brightness and tensile index of papers were decreased with the rise of loading degree. CIEL*a*b analysis shows the color differences between unmodified and modified papers. Chitosan-modified nitrocellulose membrane for paper-based point-of-care testing, Rui Hua Tang et al, Cellulose, Vol.27 . Green/sustainable cellulose paper-based platforms at point-of-care testing have received much interest in biomedical fields at resource-limited settings. In such platforms, biomolecules would have to be immobilized onto paper substrate to achieve detection. Therefore, effective molecule immobilization is critical for the performance of paper-based testing, especially the detection sensitivity. Although various methods have been developed to improve the detection sensitivity, the immobilization capacity of biomolecules has not been considered yet. In this study, we developed a facile method for modifying paper materials by incorporating chitosan into NC membrane, which has positive effect on the pore size, porosity, and surface groups of NC membrane, hence, enhancing the immobilization capacity of biomolecules on paper substrate. We demonstrated the effectiveness of the above mentioned approach by using nucleic acid lateral flow assay (NALFAs) as a model paper-based platform; in comparison with the unmodified NALFAs, the results showed ten-fold increase in the detection sensitivity for HBV. We envision that this facile modification method will have a great potential for developing other highly sensitive paper-based detecting platforms.
Technical Abstracts
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