What is the composition of the drug and from the capsules?

hello Tatiana,

Encapsulation efficiency was calculated based on the concentration of

the a.i. detected in the formulation over the initial concentration of

that a.i. in solution was added to make the formulation. the a.i. you can determined using spectroscopic or chromatographic method.

you can refer the following paper "Development of controlled release formulations of imidacloprid employing novel nano-ranged amphiphilic polymers" Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes Volume 47, Issue 3, 2012 pages 217-225.

with best wishes

totan

Dissolve the capsule in the solvent the polymer and drug will get solublise and go for spectrophotometric using respective standards. if the drug is not soluble in that solvent, add the incompatible solvent(drug should be soluble) of polymer to the first solution and extract the drug and estimate (if you are doing multiple extraction - concentrate it and estimate )

Encapsulation Efficiency = Drug in nano capsule*100/ Total Drug in formulation

Total drug in the formulation can be calculated by adding a material/chemical that can dissolve the nano capsules and allow the drug to come out in the solution. Amount of drug now in the solution can be calculated using UV or HPLC according to the ease.

To calculate amount of drug in nano capsules ,

First , separate your nano capsules from the medium in which they were suspended by centrifuging @ min 50,000 g or by filtration. Then again wash the nano capsules ,after that mix both the solution (solution after seperating nanocapsules and solution after washing ) and check the amount of drug in that solution

Now amount of drug in nanocapsules is equal to total amount of drug in formulation minus amount of drug in above solution.

Vikas Dalal thank you for your answer... but I have a problem.. my lab doesn't have ultracentrigation.. so, the other option it's ultrafiltration but, I couldn't find anything about it...

Ok you can filter the formulation through a filter whose mesh size is less than your size of nanocapsules ..suppose your 90 % capsules are more than 300nm then you can filter the formulation from 0.22 micrometer filter ...

Encapsulation efficiency can be determineted by UV or HPLC measurements

Thanks :)

Dear Tatiana,

follow this link may be helpfull for you http://sottosgroup.beckman.illinois.edu/papers/nrs064.pdf

Thank you everyone.... I'll try to read more... but I'm still don't have ultracentrifgation equipment :( I have to try another method :P

Dear Tatiana

if you don't have ultra centrifugation equipment , no need to worry ... Filtration is also used for calculation of entrapment ...you can filter your formulation after subjecting it to centrifugation (what ever centrifugation equipment you have, just centrifuge your formulation to the maximum speed that you can achieve)

then take the supernatant

then acc. to particle size of your formulation

if it is more than 500,300,150 nm then filter your supernatant from 0.44 micrometer,0.22 micrometer,0.11 micrometer filters respectively .these filters can easily purchased from market

you can try hi-media syringe driven filters made up of PVDF hydrophilic membrane ..these will come in different pore sizes like 0.44 micrometer , 0.22 micrometer, 0.11 micrometer ..

i think this might help you in ur research..

thank you so much Vikas Dalal , I have been talking about some filters with my partners, in this moment I don't remember the name :S thank you for your help ;)

It depends. Is your drug chemically stable? If it is, you should determine the free drug in the medium of suspension for your nanoparticles, but if it is unstable, doing that would result in an artificially high value for encapsulation. My advice is to dissolve the particles in a suitable solvent, dilute, and analyze for drug.

Dear Bharat : Today I did that.. but i have a big problem.. I'm doing some calibration curve with the drug and the emulsifier agent (gelatin and poloxamer) , and the blank it's poloxamer and gelatin without the drug.. But this solution didn't have absorbance 0 (zero) this changed and the drug isn't soluble in water, but in these emulsifier agent it is.. so What may I do?

Procedure for self encapsulation:

Article Fluorescence study of glucose oxidase self-encapsulated with...

I think you can try in this way ....Solubilize your nanocapsules in water(water soluble materials will get dissolves). After that extract the drug using any suitable solvent which is immiscible with water. Then do the calibration curves in that solvent for estimation of the drug.

Dear Tatiana, thank you for raising that question, i also have the same problem, now, my problem is,,, when do I measure the inintial concentration and final concentration? or I need to dissolve my formulation in a solvent and then measure the concentration then that will be initial, then I do filtration and I measure again the concetration of the solid and not the filtrate then i will call it final conc? help.

Helow every one, how to differentiate between the loading capacity and the encapsulation efficient in terms of their calculation

Depending on what your drug is you could do a gel shift assay. It's very simple and efficient. You would use a PAGE or agarose gel (density of the gel depends on what you are loading). One lane would have your drug alone, the other just the carrier and another would have the complex. Depending on how far the gel shifts down (based on molecular weight) you will know how efficient your encapsulation was. This of course also depends on the size of your molecule but you can account for that with the density of the gel. Try increasing amounts of drug, The band that doesn't move respective to the preceeding concentration will be your saturation point. If you are loading nucleic acids you can stain the gel and measure the increasing amounts of retained nucleic acid. Hope this helps, good luck!