4.2.1 Addition of Surfactants

• 4.2.1.1 Dissolve the surfactant in the aqueous phase for emulsification-based methods or mix it with the organic solvent in solvent evaporation methods.
• 4.2.1.2 For lipid-based nanoparticles, such as solid lipid nanoparticles (SLNs) or liposomes, incorporate lecithin or Tween 80 directly into the lipid matrix or surface coating.

4.2.2 Stabilization During Formulation

• 4.2.2.1 Ensure proper mixing and homogenization to allow the surfactant to adsorb onto the nanoparticle surface. This is crucial for minimizing particle aggregation and achieving uniform size distribution.

4.3 Characterization and Testing

4.3.1 Particle Size and Polydispersity Index (PDI)

• 4.3.1.1 Measure particle size and PDI using dynamic light scattering (DLS) to confirm that the surfactant has effectively reduced particle size and achieved a narrow size distribution.

4.3.2 Surface Charge (Zeta Potential)

• 4.3.2.1 Measure the zeta potential to confirm the stability of the nanoparticles. A high absolute zeta potential (> ±30 mV) indicates good colloidal stability, attributed to the surfactant’s surface activity.

4.3.3 Surfactant Residuals

• 4.3.3.1 Perform tests to determine the residual surfactant levels in the formulation, ensuring that they remain within acceptable limits to avoid toxicity or adverse effects on drug activity.

4.4 Optimization and Stability Testing

4.4.1 Surfactant Concentration Optimization

• 4.4.1.1 Adjust the surfactant concentration based on the nanoparticle stability, particle size, and zeta potential data obtained. Too much surfactant may cause particle solubilization or toxicity, while too little may result in aggregation.

4.4.2 Stability Studies

• 4.4.2.1 Conduct stability testing of the surfactant-stabilized nanoparticles under various environmental conditions (e.g., temperature, light exposure) to assess long-term stability and prevent phase separation or particle growth.

4.5 Sterility and Storage

4.5.1 Sterility

• 4.5.1.1 Filter sterilize the final nanoparticle formulation using a 0.22 µm filter if required for the intended application (e.g., injectable formulations).

4.5.2 Storage Conditions

• 4.5.2.1 Store the surfactant-stabilized nanoparticles in sealed, sterile containers at appropriate conditions (e.g., 4°C or room temperature) depending on the formulation stability data.

5) Abbreviations, if any

• DLS: Dynamic Light Scattering
• CTAB: Cetyltrimethylammonium Bromide
• SDS: Sodium Dodecyl Sulfate
• PDI: Polydispersity Index

6) Documents, if any

• Surfactant-Based Nanoparticle Formulation Logbook

7) References, if any

• Guidelines for using surfactants in nanoparticle formulations
• FDA Guidance on Nanotechnology for Drug Formulations

8) SOP Version

Version 1.0

Annexure

Surfactant-Based Nanoparticle Formulation Logbook Template

  

    
Date
    
Batch Number
    
Surfactant Used
    
Concentration
    
Particle Size
    
Zeta Potential
    
Operator Initials
    
QA Initials
  
  

    
DD/MM/YYYY
    
Batch Number
    
Surfactant Name
    
Concentration (%)
    
Size in nm
    
Value (mV)
    
Operator Name
    
QA Name