Steve - the problem of 'encapsulation' (and 'targeted release') is one of the central questions in pharmaceutical industry (and the myriad researchers working on their funding directly or indirectly). It is also very strongly represented in the food and personal products industry. In all these cases the principle is the same: you have an 'active' (which may well be a protein as in your case) and you want to protect it from various environments until the moment (in time or location) when you want this 'active' molecule to be released intact. Exactly what you want...

Now, with this amount of effort there are very many solution strategies! 

Encapsulation in small emulsion droplets (stabilised by a chosen surfactant or by colloid particles as in Pickering emulsion) and in microgel particles (with degradable polymer or physical crosslinks, allowing the dissassembly) - are the two most common, I think. But there are also very cool and advanced methods such as making "molecular boxes" - e.g. with DNA origami - where the required protein can be kept. 

Bottom line: this is a very big field, with many many answers - and you may search for the one more suitable to you by the keywords that I used in this note. 

Hi, Steve.

Have you thought of using some kind of supramolecular framework? A non-covalently bonded shell surrounding the protein might have the properties that you require.

I found this:

http://pubs.acs.org/doi/abs/10.1021/nn501040h

in the very recent literature on the topic using a Google Scholar search for "supramolecular shell drug delivery ". Perhaps this could help get you started?

-Jon

Steve - the problem of 'encapsulation' (and 'targeted release') is one of the central questions in pharmaceutical industry (and the myriad researchers working on their funding directly or indirectly). It is also very strongly represented in the food and personal products industry. In all these cases the principle is the same: you have an 'active' (which may well be a protein as in your case) and you want to protect it from various environments until the moment (in time or location) when you want this 'active' molecule to be released intact. Exactly what you want...

Now, with this amount of effort there are very many solution strategies! 

Encapsulation in small emulsion droplets (stabilised by a chosen surfactant or by colloid particles as in Pickering emulsion) and in microgel particles (with degradable polymer or physical crosslinks, allowing the dissassembly) - are the two most common, I think. But there are also very cool and advanced methods such as making "molecular boxes" - e.g. with DNA origami - where the required protein can be kept. 

Bottom line: this is a very big field, with many many answers - and you may search for the one more suitable to you by the keywords that I used in this note. 

Your question is a very broad one and I do not think it has a clear answer with the current knowledge. Also, bear in mind that there is no general rule when working with proteins. One protein may behave completely different than another in a certain condition. All that said, here are a few tips that may be helpful:

Hydrophilic carriers should perform better than hydrophobic ones with respect to protein stability

Chemical modifications (for immobilization onto a particle or as used for labeling) usually lead to destabilization of the proteins.

Procedures that require shocks (such as sudden shifts in pH and temp) are not good for proteins.

Whatever you do beware that interfaces play an important role with respect to the stability of proteins. Adsorption of proteins to solid-liquid interfaces for instance can destabilize them. You cannot avoid it but it should be controlled and minimized.

Preserving the function, although already one step ahead, is not all of the story. Proteins can be destabilized and sill function. Such samples may induce immunogenicity or lead to severe aggregation over long term storage.

This article describes some basics regarding the protein stability: Pharmaceutical Research, September 2003, Volume 20, Issue 9, pp 1325-1336

Good luck with your research.

Dear Steve,

I have heard that protein magnetic resonance spectroscopy (MRS) (also abbreviated by protein-NMR) is recently giving very encouraging results (see, for example Spronk, C. A., Nabuurs, S. B., Krieger, E., Vriend, G., and Vuister, G. W. (2004). "Validation of protein structures derived by NMR spectroscopy". Progress in Nuclear Magnetic Resonance Spectroscopy 45 (3–4): 315–337.)

Hello Steve,

Take a look at papers by Michael A. Brook (there's about 6-8 of them on this topic).  He's had success with incorporating proteins into silicone emulsions and other silicone-based matrices.  The formulations are quite easy (for the most part) to put together); simply dump and stir.  The proteins/enzymes remain stable for a significant period of time and can easily be extracted from the encapsulating system.

The best and most used method is by solvent evaporation (also called in-liquid-drying-process) using PLA or PLGA.

It really depends on the final application of the formulation. If you just have to apply on cells to deliver the protein, then I would go for liposomes. In particular, pH sensitive liposomes loaded via dehydration/rehydration. You should be able to achieve a relatively high encapsulation efficiency and release your protein directly in the cytoplasm. Outside the cell, the formulation should be stable and guarantee a controlled release of the protein.

I strongly advise you AGAINST PLGA in this case. The encapsulation for proteins is very low and the release is very slow (I would say no release). Unless, of course, you want to have an extremely long circulating formulation.

Dear Steve,

I had a question could you say the size of protein is 10 nm, do you have any literature for that. if so please let me know.

use PLGA micro particles 

I agree with Kishore, probably try chitosan. There is a lot of literature polymers using such as polyanhydrides, something that does not change the environment acidic upon degradation.

Let me know if you need help with literature.

hi. you can encasulate it with cationic niosome or chitosan that it has a nature source .