Hi,
I am preparing nanoparticles by w/o/w double emulsion method.Firstly I am sonicating w/o emulsion at 70 % amplitude for 2 minutes by using sonics vibracell ultrasonic processor 500 W, 20 kHz and then again sonicating the w/o/w emulsion for 2 minutes at 70 % amplitude using sonics vibracell ultrasonic processor 500 W, 20 kHz. Is it right?
What is your aim?
Which is your system?
What type of emulsifyiers (surface active molecules) are present in your formulation?
It is difficult to answer without any clue to data.
at high amplitude if you expose for more time it may breakdown structure and leach out entrapped drug
You are right in your procedure but the high intensity may pose several issues. First you need to make sure you encapsulated material isn't sensitive to mechanical force (like DNA and proteins), secondly you have to coll down the sample otherwise the emulsion droplets will coagulates and just won't give nice fine powder. There are two ways to avoid it, first use duty cycles (I would recommend as low as 50% minimum) but the easiest way is just to keep the vessel in an ice bath. Another very important tip, you have to be very matriculate about the drop wise, it has to be drop by drop otherwise it won't work properly.
Let me know if you have additional questions (-:
Roni should I add drop-wise through syringe? I f yes then which needle gauge size? Should I add dropwise on vortex and later sonicate it or should I add dropwise while sonicating?
I can't give you a definitive answer since I don't know which polymer and at what concentration and which solvents are you using. Also the concentration of surfactant. But I can tell you this, there are two opposing factors you need to take into account. You want to droplets to be small as possible but that makes the procedure take longer. The polymer solutions are usually very visocitic so long dropwising might make it too viscous that it would start creating strings which is the worse. I personally just use glass pippetes with a manual pump.
You can dropwise and sonicated afterward. It might reduce the time needed for ultrasound application. As long as you keep the heat generation down you're good to go.
Roni, thank you for such a useful answer. I am thinking that researchers are working with the 130 w for 2 minutes and I am working with 500 w for 4 minutes. Is not I am giving too much power?
Nope. I used to use the 600W and it was fine. Just keep the temp down that's the most important issue.
DCM is highly volatile so keep the temp down as much as possible. I would do duty cycles and ice bath. Tween 80 is nice, I used PVA 88% hydrolized.
Roni thank you, at what amplitude you sonicated your formulation and for how much time?
I found 40% to be enough, at duty cycle of 50% for 40 sec, three cycles. Please upvote my answers if you found them helpful (-:
Thank you.Can you send me that paper in which you prepared nanoparticles?
Mine is under review right now in JCR (hoping for the best (-:) but anyway it's based on the double emulsion method described in Saltzman paper: http://www.sciencedirect.com/science/article/pii/S014296120900115X
Good luck.Total time for sonication was 2 minutes for your formulation?
hey you can use 3:1 mixture of sulfuric acid and 30% hydrogen peroxide solution for this
"70% for 4 minutes" provides no indication of the energy imparted into the system. See:
Ultrasound, cavitation, and the singing kettle http://tinyurl.com/olueohz
Indeed "70%" usually means that the duty cycle is slowed to 0.7 of the 100% value. Thus the same effect occurs but over a longer time frame. I would venture that 70% for 4 minutes is identical to 100% for 0.7*4 minutes (2.8 minutes).
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