Stimuli-responsive interpolymer complex coated hollow silica vesicles

1. A method of preparing a porous hollow silica particle with a pH responsive interpolymer complex immobilized thereon, the method comprising:

a) providing a suspension comprising a porous hollow silica particle having a first polymer immobilized thereon;

b) adding a solution comprising a second polymer to the suspension to form a mixture, the second polymer selected from the group consisting of poly(methacrylic acid) and copolymers thereof and having a molecular weight in the range of from 3 kDa to 8 kDa; and

c) complexing the second polymer with the first polymer to form an interpolymer complex, wherein the interpolymer complex forms a layer round the silica particle and depending on the pH of the environment within which the silica particle is placed, the structure of the interpolymer complex layer assumes a closed or collapsed structure in which the pores of the silica particle are covered or an open structure in which the pores of the silica particle are not covered.

2. The method according to claim 1 , wherein the poly(methacrylic acid) is of the general formula (1)

wherein R a , R b and R c are independently an aliphatic, an alicyclic, an aromatic or an arylaliphatic group with a main chain of about 1 to about 30 carbon atoms and 0 to about 10 heteroatoms selected from the group consisting of N, O, S, Se and Si; and n is an integer from 2 to 10000; wherein all groups may be optionally substituted.

3. The method according to claim 1 , wherein the copolymers comprise copolymers from poly(methacrylic acid) of general formula (1) and vinyl monomers of the general formula (2)

CH 2 ═CR x R y   (2)

wherein in formula (2),

R x and R y are each independently selected from the group consisting of H, optionally substituted aliphatic, an alicyclic, an aromatic and an arylaliphatic group with a main chain of about 1 to about 30 carbon atoms and 0 to about 10 heteroatoms selected from the group consisting of N, O, S, Se and Si.

4. The method according to claim 1 , wherein the second polymer is complexed with the first polymer by hydrogen bonding.

5. The method according to claim 4 , wherein the first polymer is a polar polymer capable of forming a hydrogen bond with the second polymer.

6. The method according to claim 1 , wherein the first polymer is selected from the group consisting of poly(ethylene glycol), poly(vinyl pyrrolidone), chitosan, derivatives thereof, and copolymers thereof.

7. The method according to claim 1 , wherein the second polymer has a molecular weight of 6.5 kDa.