Nanostructured highly-swollen hydrogels: complexation with amino acids through copper (ii) ions
Answers
Explanation:
We report on the complexation of highly swollen poly(methacrylic acid) (PMAA) nanothin hydrogel films with copper (II) ions and the stability of these (PMAA)–Cu2+ complexes in amino acid solutions. ... The use of AAD as a cross-linker allows for selective binding and recognition of arginine among other amino acids.
Answer:
Complexation of highly swollen poly(methacrylic acid) (PMAA) nanothin hydrogel films with copper (II) ions and the stability of these (PMAA)–Cu2+ complexes in amino acid solutions. These networks are produced by selective cross-linking of PMAA with adipic acid dihydrazide (AAD) and ethylenediamine (EDA) in hydrogen-bonded spin-assisted layer-by-layer films. The swelling of the hydrogels at higher pH values is significantly suppressed after introducing copper (II) ions and can be restored by treatment with amino acid solutions including serine, threonine, arginine, histidine and glutamine. The hydrogel swelling recovery is controlled by Cu2+ removal from the hydrogel which is regulated by the strength of [(PMAA)n–Cu2+] complex bonding and is dependent on the amino acid type, concentration and the hydrogel's cross-linker. The use of AAD as a cross-linker allows for selective binding and recognition of arginine among other amino acids. The special affinity of the [(PMAA)16–AAD–Cu2+] hydrogel complex to arginine is due to the formation of ternary (hydrogel–copper–arginine) complexes stabilized by electrostatic interactions between the carboxylic groups of PMAA and the guanidinium side group of arginine. Our study provides new aspects of competing interactions between polyelectrolyte networks, metal ions, and amino-acids and opens prospects for developing novel analyte-responsive biosensors.