Intercalation of Ga3+-salicylidene-amino acid Schiff base complexes into layered double hydroxides: Synthesis, characterization, acid resistant property, in vitro release kinetics and antimicrobial activity

This study is aimed to evaluate the potential application of a drug delivery system of Ga3+ complexes in layered double hydroxide, i.e. [Ga(L)(2)](-)-LDH (L represents Schiff base ligands made up of salicylidene with glycine, alanine, tyrosine, phenylalanine, aspartic acid and glutamic add for complexes 1-6, respectively). The successful intercalation of Ga3+ complexes into Mg/Al-NO3-LDH by delaminating/restacking method was proved by elemental analysis, XRD, FTIR spectra, UV-vis DR spectra, TG analysis and SEM measurements. A monolayer intercalation of 5 and 6, bilayer of 1 and 3 and trilayer of 2 and 4 in interlayer region of hybrids which have extended gallery height of 11.86-21.22 angstrom were deduced. Better acid resistance than the pristine complexes in wide pH range from 7 to 1 was revealed by UV-vis spectra. The cumulative release profile of Ga3+ complexes from the hybrids in phosphate buffer (pH 7.4) following first-order kinetics via ion-exchange between guest anions and phosphate anions was established by UV-vis spectra. Antibacterial activity of hybrids with MIC values of 65-137 mu mol/L against Pseudomonas aeruginosa was demonstrated by the broth twofold dilution method. These results suggest that LDH is a promising host material for carry and controlled delivery of biologically active Ga3+ complexes. (C) 2013 Elsevier B.V. All rights reserved.