Biomacromolecules in paper for strength and bio-detection

In this work, biomacromolecules were employed as paper additives. I started with investigating a protein as adhesive for wet cellulose, and then combined biomacromolecules with paper to assemble paper-based biosensors.; Regenerated cellulose films were laminated by using very thin layers of BSA as the adhesive. The wet delamination strength was measured as functions of pit, lamination time, temperature and pressure, as well as cellulose oxidation. It is proposed that covalent attaching of BSA onto the cellulose and disulfide crosslinking within the protein layer contributed to wet adhesion.; Physical adsorption and covalent coupling as approaches for treating cellulose surfaces with an ATP-binding DNA aptamer was explored. Physical adsorption was weak and reversible. The isotherms could fit into the Langmuir equation. Amine functionalized aptamer was covalent coupled onto aldehyde modified cellulose film with the maintaining of the aptamer activity.; Poly(N-isopropylacrylamide-co-vinyl acetic acid) microgel could be immobilized on paper surfaces by simple spotting and drying due to physical entrapment Moreover, Bovine Serum Albumin and a short oligonucleotide had no non-specific interaction with the microgel. These results show the potential of using microgels coupled with bio recognition molecules (protein and DNA) for paper-based biosensing applications.; Strategies to reduce the non-specific interaction between protein/DNA with paper surface were explored. Filter paper was strengthened by polyamide-epichlorohydrin (PAE) resin and further treated with either polyacrylic acid (PAA) or carboxymethyl cellulose (CMC). PAE/PAA treated paper can facilitate more DNA to be desorbed from the paper surface than PAE/CMC treated paper does. BSA and milk protein treated paper decrease the non-specific binding of protein with filter more than the PAA and CMC do.; A first demonstration of microgel-supported biosensing inks for inexpensive paper-based detectors was developed. Paper stripes printed with carboxylic poly(N-isopropylacrylamide) microgels (MG) that were covalently modified either with an antibody or with a DNA aptamer. It was found that the antibody and the DNA aptamer retained their recognition capabilities, both in solution and on paper, after coupled to MG.