Synthesis And Application Research Of Layered Double Hydroxide Nanomaterials

Layered double hydroxides (LDHs), also called "anionic clays", have been demonstrated as attractive materials for the immobilization of biomolecules and the carrier of drug, due to their hydrophilic, swelling and anion exchange properties. The LDHs consist of M_â…¡(OH)₆ and M_â…¢(OH)₆ edge-sharing octahedral forming sheets similar to those of brucite. Net positive charges of the layer are balanced by exchangeable anions intercalated between the sheets. We synthesized LDHs (ZnAl-LDH,NiAl-LDH) films and powders via the methods of electrochemistry, hydrothermal and coprecipitation, and our results showed that the modified electrodes in this synthetic lamellar material provides an inexpensive, fast and easy method for the elaboration of electrodes without enzymes. It was a new material to fabricate biosensor. The nanotoxicology of ZnAl-LDH used as drug carrier was discussed. The detailed contents are as follows:(1) The novel inexpensive electrochemical and hydrothermal methods were used to modify Al and Zn substrates with nano-LDH films. The LDHs with different bivalent and trivalent metal ions and with different element ratio were synthesized through coprecipitation method. The morphology, structure, composing and dispersive properties of the LDH nanomaterials were characterized. The growth mechanism and influence of morphology and structure were discussed. The nanomaterials of Zn₃Al₁-LDH and Ni₃Al₁-LDH powders displayed a good dispersive property.(2) The LDH nanoflakes grown on Al substrates were used as electrochemical sensor, and the result were discussed.(3) It is first reported that the glass carbon electrode modified with monodispersed Ni₃Al₁-LDH nanoflakes and chitosan acetum solution was used as glucose biosensor. The working mechanism and concentration calibration curve of biosensor in the glucose solution were characterized with physical and electrochemical methods. The determination of glucose in samples of human serum was performed by the developed biosensor, utilizing both calibration curve and the standard addition method. The diversified influences of biosensor were also discussed.(4) The sensitivity of the developed biosensor modified with Pt nanoparticles by the method of plasma sputtering increased obviously. The size of noble metal nanoparticles could be controlled through controlling the pressure and time of the plasma sputtering.Measurement of oxidative stress was suggested to be one of the best ways to find out if nanomaterials are toxic, and even could find fundamental cause-effect relationship of nanotoxicology. Cells respond to the ZnAl-LDH with different concentration drop in the glutathione (GSH) /oxidized glutathione ratio by mounting protective or injurious responses. We also choose DNA strand break (DSB), DNA-Protein crosslink (DPC) and carbonyl content in proteins (CCP) as biomonitors. All results demonstrated that ZnAl-LDH nanomaterials should not induce obvious oxidative stress effects of Hela cell system, and it has the potential to be used as drug vehicle in biomedicine field. However further study is still be needed in vivo system.All the applied researches were progressed and based on the monodispersed property of nanomaterials, not only the Zn₃Al₁-LDH and Ni₃Al₁-LDH synthsized via the method of coprecipitation, but also the Pt nanoparticles procured with plasma sputtering. It is the aim that we take advantage of the special properties of nanomaterials.