Solid lipid nanoparticles (SLNS) are natural or synthetic lipids or lipids that are solid at room temperature. For example, with lecithin and triacylglycerol as the matrix, the drug is wrapped in the lipid nucleus to make a solid lipid particle delivery system with a particle size of about 50-1000 nm. It solves the shortcomings of general liposome instability in vivo and in vitro, and also avoids the problems of physical instability as drug carrier, low solubility of oil relative to drugs, potential toxic substances and cytotoxicity of polymer particles in the preparation process.
Fig.1 Schematic Presentation of a Solid Lipid Nanoparticle (Tenchov, 2021)
CD Formulation can provide customers with surface modification and physicochemical properties analysis of solid lipid nanoparticles. Our experts will be at your service throughout the process to ensure that we offer our customers the most cost-effective and time-saving solution.
Surface Modification of SLN
The surface modification of SLN mainly considers the effect of surface hydrophilicity and lipophilicity, surface charge and steric properties on its adsorption to opsonization proteins. It is generally believed that the stronger the lipophilicity of the surface, the stronger the phagocytosis of phagocytes, so a hydrophilic material, such as polyethylene glycol (PEG), should be selected. Negatively charged surfaces tend to make nanoparticles more easily scavenged in vivo relative to positively charged or neutral surfaces, and neutral surfaces are best used to prolong their circulation time in vivo. In addition, there are complex interactions between nanoparticles and nanoparticles and between nanoparticles and the in vivo environment, and steric repulsion can more effectively overcome the attraction of van der Waals forces than electrostatic repulsion. If the nanoparticles have better steric hindrance, their adsorption to opsonin in vivo will be weakened. Therefore, the modification of SLN surface with hydrophilic long chains is an effective method to reduce its adsorption to opsonin.
Analysis of Physicochemical Properties of SLN
1. Particle Size Detection
Laser Difference (LD) and Photon Correlation Spectroscopy (PCS) are the most powerful techniques for routine particle size determination.
2. Zeta Potential Detection
Zeta Potential Meter is to calculate the Zeta potential indirectly by measuring the moving speed of the sample in the electric field. The disadvantage of Zeta potential measurement is that the sample volume must be greater than 10 mL, otherwise the potential value cannot be detected.
3. Crystallinity and Lipid Polymorph Analysis
Differential Scanning Calorimetry (DSC) is commonly used for purity testing of crystalline drugs.The measurement of the power difference and temperature of the reference material has the advantages of rapidity, accuracy and less sample usage.
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