A new fami
ly of functiona
l hybrid nanocomposites based on the interca
lation of natura
lly occurringanionic biopo
lymers inc
luding a
lginic acid, pectin,
-carrageenan,
-carrageenan, and xanthan gum in[Zn
2A
l(OH)
6]C
l·
nH
2O
layered doub
le hydroxide (LDH), have been synthesized. The "coprecipitation"or "co-organized assemb
ly" method has been successfu
lly emp
loyed for the interca
lation of suchpo
lysaccharides within the [Zn
2A
l] LDH. However, the "reconstruction" procedure from the ca
lcinedLDH in the presence of the anionic po
lysaccharides on
ly resu
lted in a partia
l interca
lation of the organicguest. Particu
lar effort was devoted to the study of
-carrageenan-[Zn
2A
l] systems. An essentia
l featureof the prepared biopo
lymer-[Zn
2A
l] nanocomposites is that the anionic exchange capacity of the pristineLDH is turned into a cationic exchange capacity due to negative
ly charged groups in the po
lysaccharidestructure that do not interact with the positive
ly charged LDH
layers. In agreement with the fact thatmost of the studied biopo
lymers interact strong
ly with ca
lcium ions producing homogeneous ge
ls, theprepared biopo
lymer-[Zn
2A
l] nanocomposites were operative as active phases of sensors for therecognition of ca
lcium ions. Hence, the biopo
lymer-[Zn
2A
l] nanocomposites have been incorporated incarbon paste or PVC matrixes for the deve
lopment of potentiometric sensors. These devices were app
liedto ca
lcium determination by direct potentiometry and the best responses were obtained for the sensorsbased on a
lginate-LDH and
-carrageenan-LDH nanocomposites.