I have a polystyrene microsphere sourced which are not functionalized, and hence do not have any surface group such as a carboxyl or amine. I wish to introduce a surface group such as a carboxyl or hydroxyl etc. to perfom covalent coupling with NHS and DCC for protein attachment. I have not been able to find a reliable method for this method. Please suggest what is the best way to move ahead?
Koehler has the best approach but I would use a substituted phospholipid to coat the particle surfaces., for example phosphotidylethanolamine or phosphotidylserine. You will find literature references for this approach. Adsorption of these materials to polystyrene surfaces is simple. Chemical activation is possible but technically more difficult. Depending of the coating agent you can introduce alcohols, amines, sulfhydryl groups, or carboxylic acids as desired and also control the net charge. A secondary coating can be applied to reduce non-specific binding, For example, coat phosphatidic acid coated particles with an aminodextran, or coat phosphotidylethanolamine coated particles with carboxymethyldextran. That said, by far the simplest approach is to buy the particles from one of the many commercial suppliers
Dear Rohan:
Polystyrene has the properties of benzene. It can be sulfonated. Then get out of benzenesulfonic benzosulfonamid. See procedure for the synthesis of these materials and apply them to the surface modification of styrene.
Best regards.
CO2, N2, plasma surface treatment will create anchoring function such as Carboxylic acid, aldehydes, ketoses and amines respectively. Non invasive technique and no need of any solvent. All the best.
Polystyrene has the reactivity of alkylbenzenes. Depending on the desired functionality, polystyrene can be sulfonated, nitrated, halogenated, chloromethylated, etc. The new functionality can be further modified. For instance, polystyrene can be alkylated with chloroacetic acid to insert carboxylic groups. Chloromethylated polystyrene (also a commercial product) can be hydrolyzed to hydroxymethylated polystyrene.
Chloromethylation is a good starting point, please be aware that the chloromethylation route uses some quite nasty chemicals which should be taken into consideration. If the bead has low crosslinking then you will need to remove the residual linear polystyrene (low MW) if this hasn't been done by the supplier. This will remove the leachables you will get when coupling protein to the resin.
For most applications the hydrophobic nature of the resin support will limit it's use for protein immobilisation unless using organic solvents. If the final immobilised resin is intended for us in aqueous you may have to consider using an acrylic or agarose resin.
The simplest method would be the 1st suggestion I.e. Sulfonation eg. using chlorosulfonic acid check out DOI: 10.1021/ie9012858 and references cited therein.
Thank you for your replies.
Is adding sulphuric acid a good idea? I read that it can directly form carboxyl group by cleavage of polymer on surface.
Can't see how H2SO4 would produce COOH functionality on polystyrene. I doubt it alone is strong enough to oxidatively cleave the aromatic rings. Nitrration with HNO3/H2SO4 followed by SnCl2 reduction is a routine method if you want amine functionality.
The simplest way would be to use hydrophobic-hydrophobic interactions and not covalent bonds to functionalize the polystyrene. For amino groups you can use oleylamine or dimer diamine, for hydroxy groups oleyl alcohole or dimer diol and for COOH-groups oleic acid or dimer acid. It would be sufficient to swell the PS-microspheres with one of these reagents. The hydrophobic-hydrophobic interactions will remain stable if you make your further derivatizations in aqueous media, that means EDC instead of DCC as coupling reagent.
Dear Rohan,
I suggest you to use PSMA copolymer instead of PS. Poly(styrene-co-maleic acid) (PSMA) is an important reactive thermoplastic polymer known to possess amphiphilic properties. With this kind of copolymer you can prepare spherical micelle easily.
Dear all,
you can peerform a chloromethylation at the para position which allow to do a variety of functional groups integration. Regards
Koehler has the best approach but I would use a substituted phospholipid to coat the particle surfaces., for example phosphotidylethanolamine or phosphotidylserine. You will find literature references for this approach. Adsorption of these materials to polystyrene surfaces is simple. Chemical activation is possible but technically more difficult. Depending of the coating agent you can introduce alcohols, amines, sulfhydryl groups, or carboxylic acids as desired and also control the net charge. A secondary coating can be applied to reduce non-specific binding, For example, coat phosphatidic acid coated particles with an aminodextran, or coat phosphotidylethanolamine coated particles with carboxymethyldextran. That said, by far the simplest approach is to buy the particles from one of the many commercial suppliers
You could perform sequential layering of polyelectrolytes. Polystyrene sulfonate and Polyallyamine hydrochloride in alternating layers could provide either sulfonate or amine functionality. Using polyacrylic acid can give carboxyl groups.
I suggest you to use PSMA with maleic anhydeid as functional group instead of PS. After perparation of PSMA microspheres, they can be attached easily to protein.
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