Our method in loading drug in micellar carrier is one step process in which polymer and drug is poured into solvent then sonicated to micell formation and drug loaded into the micell. I would like to know how could measure the amount of drug which encapsulated into micelles?
I should mention that centrifugation is not applicable for this kind of carrier, because miclles need very high speed centrifugation to precipitate.
You may determine the condition in which micelles disrupt, and following micelle disruption pass the formulation 1 ml through sephadex column (G 50 grade). Drug will be eluted first, dilute it appropriately and determine the concentration using UV or HPLC.
Good luck
Do you have a polyelectrolyte for your polymer, or is it a surfactant? Assuming that the drug is insoluble in your solvent, sonication should reduce particle size, and your surfactant "solubilizes" the drug. So centrifugation should work; your are not precipitating the micelles, but spinning down the unencapsulated drug. You should be able to determine the encapsulated drug by mass balance.
Dear Kamal
Thank you for your helpful answer.
The polymer which used to make micelles is amphiphilic polymer whit out using surfactant. I should mention the drug which I used is not soluble in solvent that micelles is prepared. As you said, I think it's better to use centrifugation regarding to precipitate unencapsulated drug,
You can use UV-Vis spectrophotometry. You may start by first building a calibration curve for your drug (as a function of concentration and absorbance). Then, using the calibration curve you should be able to deduce the drug concentration in the polymeric micelles. Hope this helps.
First you have to centrifuge your formulation to make "sedimente" the unloading drug, then take the supernatant and disrupt the micelle with a solvent which solubilze both your drug and your surfactant, and analyse the whole in HPLC or UPLC
First, you use from centrifugation for separate of un-encapsulated drug and then with common solvent (for drug and polymer) which dissolve them and analyze amount of encapsulated drug with UV or HPLC.
To determine partition in micelle you might want to use ultrafiltration. If you use a ultrafiltration (UF) device with a 3 kDa molecular weight cutoff you can separate the continuous phase (assuming it's aqueous) from micelles. Assay the filtrate for drug.
Assay the formulation. Subtract the concentration determined from assay of aqueous phase and you should be left with amount of drug in micelle phase.
This approach and others can be found in the following:
https://www.ncbi.nlm.nih.gov/pubmed/25909868
http://www.sciencedirect.com/science/article/pii/S0021979708002336
Regards,
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