- Factsheets
- Briefings
- General Sector Reports
- Economic Data
- Societal Issues
- Regulation & Standards
- HSE & Risk
- Business Tools
- Communication
report
2.2.3.2.2 Formulations using other nanostructured materials
Silica has been developed and commercialised for a number of years for medical applications[i], as it is known to be biocompatible and biodegradable. It can also be engineered as hollow nanoparticles with different pore diameters and shells of different thickness. This has led a number of research groups to investigate its potential as a drug delivery vehicle for medical and veterinary treatments, and more recently for pesticides, such as avermectin and validamycin, where it has been shown to afford protection against UV degradation and controlled release dependent on pore diameter and shell thickness[ii],[iii]. Nano silica has been reported to provide insecticide activity on its own, through dessication of insects’ cuticles. It has also been successfully applied as a thin film to boost cereal germination and decrease fungal growth[iv].
Nano clays and layered double hydroxides are also being developed in this regard[v]. Both materials show good biocompatibility, low toxicity and the potential for controlled release. Chemicals can be loaded between layers of both materials (an arrangement that can be influenced by buffer conditions, in particular pH). In the case of hydrophobic chemicals, this arrangement prevents re-crystallisation, increases solubility, and therefore bioavailability.
For nano clays controlled release can be engineered through coating with different polymers, which manipulates electrostatic interactions between the chemical load and the clay particles[vi]. In addition, nano clays can protect against UV-degradation of pesticides[vii].
Layered double hydroxides have high affinity for anionic species and are dissolved in acidic conditions. A number of experimental studies have demonstrated their potential use in the deployment of agrochemicals such as fertilisers[viii], plant growth promoters[ix], and pesticides[x].
[i] pSivida manufactures BioSilicon for drug delivery purpose in a number of medical conditions: www.psivida.com
[ii] LIU, F., WEN, L. X., LI, Z. Z., YU, W., SUN, H. Y. & CHEN, J. F. (2006) Porous hollow silica nanoparticles as controlled delivery system for water-soluble pesticide. Materials Research Bulletin, 41, 2268-2275.
[iii] LI, Z. Z., XU, S. A., WEN, L. X., LIU, F., LIU, A. Q., WANG, Q., SUN, H. Y., YU, W. & CHEN, J. F. (2006b) Controlled release of avermectin from porous hollow silica nanoparticles: Influence of shell thickness on loading efficiency, UV-shielding property and release. Journal of Controlled Release, 111, 81-88.
[v] CHOY, J. H., CHOI, S. J., OH, J. M. & PARK, T. (2007) Clay minerals and layered double hydroxides for novel biological applications. Applied Clay Science, 36, 122-132.
[vi] LEE, W.F. & FU, Y.T. (2003) Effect of montmorillonite on the swelling behavior and drug-release behavior of nanocomposite hydrogels. Journal of Applied Polymer Science, 89, 3652–3660.
[vii] EL-NAHHAL, Y., NIR, S., MARGULIES, L. & RUBIN, B. (1999) Reduction of photodegradation and volatilization of herbicides in organo-clay formulations. Applied Clay Science, 14, 105-119.
[viii] OLANREWAJU, J., NEWALKAR, B. L., MANCINO, C. & KOMARNENI, S. (2000) Simplified synthesis of nitrate form of layered double hydroxide. Materials Letters, 45, 307-310.
[ix] BIN HUSSEIN, M.Z., ZAINAL, Z., YAHAYA, A.H. & FOO, D.W. (2002) Controlled release of a plant growth regulator, alpha-naphthaleneacetate from the lamella of Zn–Al-layered double hydroxide nanocomposite. Journal of Controlled Release, 82, 417-427.
[x] LAKRAIMI, M., LEGROURI, A., BARROUG A., DE ROY A. & BESSE, J.P. (2000) Preparation of a new stable hybrid material by chloride-2,4-dichlorophenoxyacetate ion exchange into the zinc–aluminium–chloride layered double hydroxide. Journal of Materials Chemistry, 10, 1007-1011.
Document details:
Visits: 14, Published on: November, 7th 2008, 04:52 PM, Last edit: 2009-08-14 11:43:47 Size: 5 KByte
Tags: sensor, diagnostic, nano-emulsion, cantilever, nano clay, precision agriculture, pesticide, nanocomposite, biogenesis, quality control