"Solid lipid nanoparticles (SLN)
Solid lipid nanoparticles (SLN) have attracted increasing scientific and commercial attention during the last few years in pharmaceutical and food sciences ( [Awad et al., 2008] , [Gallarate et al., 2009] , [Taylor et al., 2007] , [Varshosaz et al., 2010] and [Varshosaz et al., 2009] ). SLNs are particles consisting of a matrix made of solid lipid shell (Müller, Dingler, Schneppe, & Gohla, 2000). Compared to nanoemulsions and liposomes, SLNs have some distinct advantages ( [Mäder and Mehnert, 2005] , [Mehnert and Mader, 2001] , [Müller and Runge, 1998] and [Saupe and Rades, 2006] ), which include:
• Having high encapsulation efficiency.
• Avoiding use of organic solvents in their preparation.
• Possibility of large-scale production and sterilization.
• Providing high flexibility in controlling the release profile due to solid matrix.
• Slower degradation rate allows bioactive release for prolonged times.
• The solid matrix can (but need not) protect the incorporated bioactive ingredients against chemical degradation.
In support of above advantages, it should be mentioned that bioactive ingredient release from nanoemulsions, which takes place based on the partitioning coefficient and the phase ratios of oil and water phases, is too fast (Washington, 1998). Longer release times can be achieved with liposomes. However, it is not yet appropriate for delivery of bioactive food ingredients. Compared to these carriers, release period for SLN is longer because of increase of degradation time of solid matrix. Solid matrix is able to provide more protection against chemical reactions such as oxidation (Müller et al., 2000). ------------------
Generally, there are three models for the incorporation of bioactive components into SLNs: (i) Homogeneous matrix model; (ii) Bioactive-enriched shell model; and (iii) Bioactive-enriched core model. The type of obtained model depends basically on the formulation components (lipid, lipophilic or hydrophilic bioactive compound and surfactant) and the production conditions (hot or cold homogenization). ------------------
Nanostructure lipid carrier (NLC)
In spite of having different advantages, SLNs have some potential problems such as low encapsulation load and possibility of explosion during storage. With increasing the purity of applied lipid, less space is available to accommodate drug and nutraceutical molecules, hence encapsulation efficiency decreases and explosion risks increases due to formation of α and β′ into perfect β transition form (Westesen et al., 1997).
Radtke and Müller (2001) developed a novel carrier namely nanostructure lipid carrier (NLC) for overcoming the limitations of SLNs. NLC can be produced by mixing very different lipid molecules i.e. solid lipids with liquid lipids (oils) based on preparation methods described for SLN. The produced matrix of the lipid particles demonstrates a melting point depression compared to the original solid lipid. In fact by giving the lipid matrix a certain nanostructure, the encapsulation load of bioactive ingredient is enhanced and expulsion phenomenon during storage is limited by preventing the formation of perfect crystals ( [Chen, Tsai et al., 2010] , [Müller et al., 2002a] and [Müller et al., 2002b] ). It is also reported that NLCs have smaller particle sizes compared to SLNs (Fang, Fang, Liu, & Su, 2008). A pharmaceutical study by Teeranachaideekul, Müller, and Junyaprasert (2007) for the investigation of chemical stability enhancement of ascorbyl palmitate (AP) after incorporation into NLCs showed that addition of antioxidants as well as selection of suitable surfactants and solid lipids improved the chemical stability of AP. Investigation physicochemical properties proved that NLCs have zeta potentials ranging from −13.4 to −23.5 and show a sustained release mechanism and no obviously burst release in gastrointestinal condition (Zhuang et al., 2010). This study demonstrates the possibility of NLC application for the encapsulation of lipophilic nutrients such vitamin E and omega 3 fatty acids. ----------------
Concluding and future remarks
Despite the strong upsurge in the investigations of nano-delivery systems and proven role of nanoencapsulation in enhancing bioavailability, solubility and protection of food ingredients, there is no comprehensive information on different aspects of lipid-based nanocarriers. In this paper we attempted to provide an overview of latter developments of four lipid based encapsulation systems namely nanoemulsions, liposomes, solid lipid nanoparticles and nanostructure lipid carriers. Recent studies revealed that applying the two latter nanocarriers have considerable advantages such as having more stability, longer release time and sustained release profile over the conventional encapsulation systems. However, future trends in nano-delivery systems should focus more on investigations pertaining to the physicochemical properties of the nanocarriers as well as the properties and interactions of food systems incorporating nanoencapsulated bioactives. On the other hand, more studies are necessary for modeling the release kinetics of nanoencapsulated food components using the available equations as well as the recent novel models. This comprises one of the future objectives of our research team."
Here is a link if you want to read the entire report.
http://www.sciencedirect.com/science/article/pii/S0924224411001543
tags:
nutrigenomics human nutrition food safety food wars hunger malnutrition poverty genetics nanotechnology robotics kurzweil monsanto dupont pioneer corn genetically modified usda fda eggs beef poultry pork turkey fish shellfish fruits vegetables food borne illness wheat rice oats barley sorghum soybeans alfalfa protein vitamins minerals amino acids fats unidentified growth factors fatty acids genetic engineering climate change food security agribusiness fresh produce desertification nanoliposomes solid lipid nanoparticles nanoemulsions
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