RESUMEN
In the crystal structure of the title hydrate, C(8)H(4)Br(2)O(4)·H(2)O, O-Hâ¯O hydrogen bonds link the mol-ecules into a two-dimensional network parallel to (10-2). The acid groups of the main mol-ecule and the water mol-ecule are all involved in the supra-molecular structure. The dihedral angles between the benzene ring and the acid groups are 37.8â (4) and 36.4â (5)°, while the dihedral angle between the acid groups is 10.9â (4)°.
RESUMEN
We have developed a robust method for the visual detection of heavy metal ions (such as Hg(2+) and Pb(2+)) by using aptamer-functionalized colloidal photonic crystal hydrogel (CPCH) films. The CPCHs were derived from a colloidal crystal array of monodisperse silica nanoparticles, which were polymerized within the polyacrylamide hydrogel. The heavy metal ion-responsive aptamers were then cross-linked in the hydrogel network. During detection, the specific binding of heavy metal ions and cross-linked single-stranded aptamers in the hydrogel network caused the hydrogel to shrink, which was detected as a corresponding blue shift in the Bragg diffraction peak position of the CPCHs. The shift value could be used to estimate, quantitatively, the amount of the target ion. It was demonstrated that our CPCH aptasensor could screen a wide concentration range of heavy metal ions with high selectivity and reversibility. In addition, these aptasensors could be rehydrated from dried gels for storage and aptamer protection. It is anticipated that our technology may also be used in the screening of a broad range of metal ions in food, drugs and the environment.