Solubilize Peptide in Oil

Hi guys!

I have a water soluble peptide and I'm looking to solubilize it into a mixture of squalane and caprylic/capric triglyceride.

I was able to solubilize the pure peptide in its powder form into Caprylic/Capric Glycerides Polyglycerin-10 Esters however the shelf is only 4 months on that ingredient so its not ideal.

I was thinking of solubilizing the peptide in a small amount of water and emulsifying it into the oils with an emulsifier like Sorbitan Oleate.

What would be the best way to emulsify approximately 3% water into 50%/47% squalane/CCT?

Thanks for your help!


  • PharmaPharma Member, Pharmacist
    Depends which peptide you have.
    Many peptides have a very short shelf life once dissolved in water (I'm talking hours to days). Cosmetics gives a sh** about it because most (in many countries by definition all, that's the difference between cosmetics and pharmaceuticals) have no pharmacological activity if applied to skin anyway.
    Some peptides can be dissolved in non-aqueous solutions wherein they are a lot more stable than in water.

  • Hi @Pharma, this peptide is one designed by my company and it is water soluble but is glycosylated so it has a good degree of stability in water. It has amphiphilic properties so it can be dispersed in certain esters like mentioned above. Unfortunately the peptide now must be dissolved in water as a raw material (for manufacturing reasons) so we are looking to incorporate the peptide solution (about 3% w/w) into a mixture of oils.
  • PharmaPharma Member, Pharmacist
    Okay. Sounds interesting (but you're probably not going to share in-depth company secrets with me here, are you?).
    What's the concentration you're going for? If you are using a diluted solution, you could likely use any sort of w/o emulsifier system or a mixture of mainly w/o plus some o/w. I'd use a mixture of two to three nonionic/zwitterionic ones and simply try to make an "empty" emulsion at first so you're not going to waste any of your peptide during the first trial and error runs. Me personally, today and because it's Monday, I'd start with polyglyceryl polyrhizinoleate as main emulsifier and either hydrogenated lecithin or Xyliance as auxiliary emulsifier. Mind, there's no rational reason behind my choice! The choice is only yours and might be influenced by things like colour/turbidity, consistency, viscosity... probably these factors are more important than the peptide itself.
    You may want to think about using a gelling agent (for water and/or oil), a polyol (to reduce water activity) and some magnesium salt (if the peptide tolerates that) to increase emulsion stability.
  • Thanks for the comments @Pharma ! Unfortunately I can't share too much haha - but the peptide I guess is besides the point, it's more about creating a stable w/o emulsion. I was thinking of trying lecithin, I'll have to order it but I do have ecogel on hand (Lysolecithin (and) Sclerotium Gum (and) Xanthan Gum (and) Pullulan). Is this something worth trying?

    I tried just 3% water, oils and polyglyceryl-4 oleate (in various concentrations) but I get some sedimentation at the bottom.
  • PharmaPharma Member, Pharmacist
    Polyglyceryl-4 oleate is a low HLB emulsifier, suitable for the desired w/o emulsion whereas lysolecithin is mainly a o/w emulsifier but can be used in combination with low HLB emulsifiers for w/o.
    Use HLB values!
    Squalane/CCT 1:1 has an HLB requirement of 8. 8 is the HLB "exactly" between o/w and w/o emulsions. Given the small quantity of water you're going to add, a w/o should work. An HLB of 8, or better try 7.5 could be achieved with sorbitan oleate (HLB 4.3, 3 parts) plus lysolecithin (HLB 9, 7 parts) or polyglyceryl-4 oleate (HLB ~5-6, 4 parts) plus lysolecithin (HLB 9, 6 parts). This is, if you know how many % lysolecithin are in ecogel!
    Which emulsifiers do you have in stock?
  • @Pharma, I see what you're saying. I don't have the % of lysolecithin in ecogel. I have Glyceryl Stearate SE, Emulgade PL 68/50 (Cetearyl Glucoside (and) Cetearyl Alcohol) and Tegosoft GMC 6 (PEG-6 Caprylic/Capric Glycerides) on hand but that's about it. I don't have any additional emulsifiers but I can get anything relatively quickly off of Making Cosmetics or samples from select suppliers.
  • PharmaPharma Member, Pharmacist
    You could also add a few % wax, cetylalcohol, cetyl palmitate or similar. This would gel your low-viscosity oil and lower its HLB requirement. This increases emulsion stability and is better suited for w/o emulsions. It will however have a lower spreadability.
    Alternatively, adding hydrogenated peanut oil or lanolin will slightly lower or respectively slightly rise HLB requirement but also "gel" the oil phase and take up some water without the help of emulsifiers and still be stable. However, it will become opaque and occlusive or tacky, respectively.
Sign In or Register to comment.