Silica micro- and nano-capsules and methods for making them

Patent metadata

Field	Value
Publication number	US-2016193581-A1
Application number	US-201414917181-A
Country	US
Kind code	A1
Filing date	Sep 16, 2014
Priority date	Sep 16, 2013
Publication date	Jul 7, 2016
Grant date	—

Abstract

The present invention relates to emulsion-templated silica micro and nano-capsules- and methods for making them. In particular, the template emulsion is stabilized by a biosurfactant that also assists in nucleating the silica shell Mineralizing biosurfactants and stabilized micro- and nano-emulsions useful in forming the emulsion-templated micro- and nano-capsules, and methods for the use of the silica micro- and nano-capsules are also described.

First claim

1 . A mineralizing biosurfactant comprising:
i) a surface-active polypeptide module at least 6 amino acid residues in length; and ii) a charged peptide module 5 to 40 amino acid residues in length comprising at least one hydrogen bond donating amino acid residue and at least one positively charged amino acid residue;
wherein the surface-active polypeptide and the charged peptide modules are conjugated to one another.

2 . The mineralizing biosurfactant according to claim 1 wherein the surface-active polypeptide is an amphiphilic polypeptide.

3 . The mineralizing biosurfactant according to claim 2 , wherein the amphiphilic polypeptide has α-helical secondary structure with a hydrophobic face and a hydrophilic face.

4 . The mineralizing biosurfactant according to claim 1 wherein the surface-active polypeptide module comprises an amino acid sequence:
(a b c d d′ e f g) n

wherein n is an integer from 2 to 12;
amino acid residues a and d are hydrophobic amino acid residues;
amino acid residue d′ is absent or is any amino acid residue;
at least one of residues b and c and at least one of residues e and f are hydrophilic amino acid residues and the other of amino acid residues b and c and e and f are any amino acid residue;
amino acid residue g is any amino acid residue.

5 . The mineralizing biosurfactant according to claim 4 wherein n is 2 to 4.

6 . The mineralizing biosurfactant according to claim 4 wherein each amino acid residue a and d is independently selected from L -alanine, L -valine, L -leucine, L -methionine, L -isoleucine, L -phenylalanine, L -tyrosine, D -alanine, D -valine, D -leucine, D -methionine, D -isoleucine, D -phenylalanine and D -tyrosine.

7 . The mineralizing biosurfactant according to claim 4 wherein each amino acid residue b is independently selected from alanine, leucine, valine, methionine, isoleucine, L -serine, L -threonine, L -cysteine, L -tyrosine, L -asparagine, L -glutamine, L -lysine, L -arginine, L -histidine, aspartic acid and glutamic acid.

8 . The mineralizing biosurfactant according to claim 4 wherein each amino acid residue c is independently selected from L -serine, L -threonine, L -cysteine, L -tyrosine, L -asparagine, L -glutamine, L -lysine, L -arginine, L -histidine, L -aspartic acid and L -glutamic acid.

9 . The mineralizing biosurfactant according to claim 4 wherein each amino acid residue e is independently selected from L -alanine, L -valine, L -leucine, L -isoleucine, L -serine, L -threonine, L -aspartic acid and L -glutamic acid, especially L -alanine, L -serine and L -glutamic acid.

10 . The mineralizing biosurfactant according to claim 4 wherein each amino acid residue f is independently selected from L -serine, L -threonine, L -cysteine, L -tyrosine, L -asparagine, L -glutamine, L -lysine, L -arginine, L -histidine, L -aspartic acid and L -glutamic acid.

11 . The mineralizing biosurfactant according to claim 4 wherein each amino acid residue g is independently selected from L -alanine, L -valine, L -leucine, L -isoleucine, L -serine, L -threonine, L -asparagine L -lysine, L -glutamic acid and L -glutamine.

12 . The mineralizing biosurfactant according to claim 1 wherein the positively charged peptide module comprises 1 to 8 hydrogen bond donating amino acid residues.

13 . The mineralizing biosurfactant according to claim 1 wherein the charged peptide module comprises 4 to 12 positively charged amino acid residues.

14 . The mineralizing biosurfactant according to claim 1 having one of the following sequences:

SEQ ID NO: 155

Ac-MKQLAHSVSRLEHA-SSKKSGSYSGSKGSKRRIL-NH 2

SEQ ID NO: 156

Ac-MKQLAHSVSRLEHA-RKKRKKRKKRKKGGGY-NH 2

SEQ ID NO: 157

MDPSMKQLADSLHQLARQVSRLEHADPSMKQLADSLHQLARQVSRLEHA

DPSMKQLADSLHQLARQVSRLEHADPSMKQLADSLHQLARQVSRLEHAE

PS-RKKRKKRKKRKKGGGY.

15 . A stabilized micro- or nano-emulsion comprising an oil phase, an aqueous phase and a mineralizing biosurfactant according to claim 1 , wherein the mineralizing biosurfactant is located in the region of the interface between the oil and aqueous phases.

16 . (canceled)

17 . The stabilized micro- or nano-emulsion according to claim 15 further comprising a metal ion selected from calcium, magnesium, copper, nickel and zinc ions.

18 . A silica micro- or nano-capsule comprising an oil core stabilized by a surface film of mineralizing biosurfactant according to claim 1 and a silica shell encapsulating the stabilized oil core.

19 . The silica nanocapsule according to claim 18 having an average diameter of between 70 and 500 nm or an average diameter of between 1 μm and 5 μm.

20 . (canceled)

21 . The silica micro- or nano-capsule according to claim 18 wherein the silica shell has a thickness in the range of 10 nm to 60 nm.

22 . The silica micro- or nano-capsule according to claim 18 wherein the oil core further comprises a compound for delivery to a human or animal or a household, industrial or agricultural environment.

23 . (canceled)

24 . The silica micro- or nano-capsule according to claim 18 further comprising a pharmacokinetic modifying agent and/or a targeting agent, wherein said pharmacokinetic modifying agent and/or a targeting agent are located on the surface of the micro- or nano-capsule.

25 . A composition comprising the micro- or nano-capsules according to claim 18 together with an acceptable carrier.

26 . A method of making a silica micro- or nano-capsule comprising the steps of:
A) forming a stabilized micro- or nano-emulsion by mixing a composition comprising:
a) an oil phase;
b) an aqueous phase; and
c) a mineralizing biosurfactant according to claim 1 ; and
B) mixing the nanoemulsion with silica or a silica precursor.

27 . The method according to claim 26 wherein the micro- or nano-emulsion is formed by mixing, sonification or homogenisation.

28 . The method according to claim 26 wherein the silica or silica precursor is selected from tetraethoxysilane, tetramethoxysilane, sodium silicate (Na 2 Si 3 O 7 ), dipotassium silicon triscatecholate (K 2 [Si(C 6 H 4 O 2 ) 3 .2H 2 O), silica sol (silica nanoparticles with diameter of 10-12 nm, 40% SiO 2 , 0.4% Na 2 O), ethylene glycol modified silane (SiC 2 H 8 O 2 ) 4 ), methyltriethoxysilane, phenyltriethoxysilane and trimethylethoxysilane.

29 . (canceled)

30 . The method according to claim 26 wherein the reaction of step B) is mixed for 10 to 80 hours.

31 . The method according to claim 26 wherein the

Assignees

• Univ Queensland

Inventors

• Middelberg Anton Peter Jacob
• Zhao chun-xia
• Wibowo David
• Peters Brenton Charles

Classifications

• C07K7/06 Primary

  having 5 to 11 amino acids · CPC title

• A01N25/30

  characterised by the surfactants · CPC title

• A01N25/28

  Microcapsules {or nanocapsules} · CPC title

• B01F17/005

  Operations & Transport · mapped topic

• C07K14/001

  by chemical synthesis · CPC title