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Substance-encapsulating vesicle and process for producing the same UPDATE_EN

Foreign code F180009411
File No. AF12-07US2
Posted date Apr 20, 2018
Country United States of America
Application number 201715660746
Gazette No. 20180015036
Gazette No. 10357454
Date of filing Jul 26, 2017
Gazette Date Jan 18, 2018
Gazette Date Jul 23, 2019
International application number JP2011061790
International publication number WO2011145745
Date of international filing May 23, 2011
Date of international publication Nov 24, 2011
Priority data
  • P2010-117821 (May 21, 2010) JP
  • P2010-117823 (May 21, 2010) JP
  • 2011JP61790 (May 23, 2011) WO
  • 201213699238 (Nov 20, 2012) US
Title Substance-encapsulating vesicle and process for producing the same UPDATE_EN
Abstract Provided is a method for easily and efficiently producing encapsulated substance vesicles wherein a substance is encapsulated in the cavity of vesicles obtained by polymer self-assembly. Empty vesicles that have membranes comprising a first polymer that is a block copolymer with uncharged hydrophilic segments and a first kind of charged segments and a second polymer with a second kind of charged segments that carry a charge that is the opposite of said first kind of charged segments as well as spaces that are enclosed by said membranes are mixed in an aqueous medium with the substance that is to be encapsulated in the spaces.
Outline of related art and contending technology BACKGROUND ART
It is known that a vesicle can be formed via self-assembly of polymers of which the primary structures have been controlled precisely. Such a vesicle is applicable to various molecular designs, and can serve a new function beyond the properties of the original polymers. Accordingly, the vesicle is being considered for use as a carrier for a drug delivery system (DDS) or as a biomaterial or functional material.
Patent Document 1 (JP-H8-188541A, of which the inventors overlap with the present inventors) discloses a drug carrier in the form of an electrostatically-united polymeric micelle formed via self-assembly of a block copolymer having an uncharged segment and a charged segment.
Non-Patent Document 1 (Schlaad H. et al., Macromolecules, 2003, 36 (5), 1417-1420) discloses a vesicle formed via self-assembly of a first block copolymer having poly(1,2-butadiene) block and poly(cesium methacrylate) block with a second block copolymer having polystyrene block and poly(1-methyl-4-vinylpyridinium iodide) block (referred to as “polymersome”).
Patent Document 2 (WO2006/118260A, of which the inventors overlap with the present inventors) discloses a vesicle formed via self-assembly of a first block copolymer having an uncharged hydrophilic segment and a cationic segment (e.g., PEG-polycation) with a second block copolymer having an uncharged hydrophilic segment and an anionic segment (e.g., PEG-polyanion).
Non-Patent Document 2 (Anraku Y. et al., J. Am. Chem. Soc., 2010, 132 (5), 1631-1636, of which the authors overlap with the present inventors) discloses a vesicle formed via self-assembly of a block copolymer having an uncharged hydrophilic segment and a charged segment (e.g., PEG-polycation) and a copolymer charged oppositely to the charged segment of the block copolymer (e.g., polyanion).
It is contemplated that such vesicles formed via self-assembly of polymers as mentioned above can encapsulate and carry various substances within their cavities for desired applications (for overview, see, e.g., Non-Patent Document 3: H. Nyin et al. Soft Matter, 2006, 2, 940-949; and Non-Patent Document 4: “liposome: New Developments in Applications”, supervised by Kazunari AKIYOSHI et al., NTS Inc., 2005).
A typical process of producing a vesicle encapsulating a substance within its cavity (hereinafter also referred to as “substance-encapsulating vesicle”) includes mixing a substance to be encapsulated (hereinafter also referred to as “encapsulation-target substance”) with membrane component polymers or a preformed polymer membrane to cause formation of a polymer vesicle via self-assembly simultaneously with enclosure of the substance into the vesicle cavity (hereinafter also referred to as “simultaneous mixing method”). Examples include: emulsion method (see, e.g., Non-Patent Document 5: F. Szoka, Jr et al., Proc. Natl. Acad. Sci. USA, 1978 75 (9) 4194-4198); and instillation method using organic solution of lipids (see, e.g., Non-Patent Document 6: Batzri, S. et al., Biochim. Biophys Acta 1973, 298, 1015-1019).
However, the simultaneous mixing method has a drawback that presence of the encapsulation-target substance may affect vesicle formation process via self-assembly, thereby preventing formation of a vesicle or, even if not, enclosure of the substance into the vesicle cavity. Another problem involved in this method is that it often requires use of organic solvent which is detrimental to membrane formation, rendering the process complicated and causing damage to the encapsulation-target substance due to the organic solvent. This method has still another drawback that it is difficult to form vesicles having uniform particle size and structure unless carrying out an additional step, which is likely to render the process complicated. Thus, this method lacks versatality, and is not practical as a means for producing various kinds of substance-encapsulating vesicles.
On the other hand, as a general method of producing a particle encapsulating a substance, there is a method in which an encapsulation-target substance is introduced into the cavity of an existing vacant particle such that the substance is enclosed and carried by the particle (hereinafter also referred to as “post-carrying method”) (see, e.g., Non-Patent Document 7: W. Tong et al. J. Phys. Chem. B, 2005, 109, 13159-13165). This method could be an option for producing substance-encapsulating vesicles.
However, application of the post-carrying method to vesicles would require any additional means to introduce an encapsulation-target substance beyond the membrane of a vacant vesicle into the vesicle cavity. A conceivable method includes: making the vacant vesicle swell to relax the membrane; penetrating the encapsulation-target substance into the cavity through cleavage which has occurred on the relaxed membrane; and contracting the membrane to prevent release of the encapsulation-target substance. Another conceivable method includes: opening pores on the membrane of the vacant vesicle; introducing the encapsulation-target substance into the cavity through the pores; and closing the pores to prevent release of the encapsulation-target substance. However, these methods are cumbersome and complicated, too disadvantageous to be put into practical use. In addition, the particle size and the structure of the existing vacant vesicle would probably be disturbed during the process of enclosure and carriage of the encapsulation-target substance. Accordingly, these methods have been considered as being far from practical.
Another published method for lipid bilayer membrane vesicles such as liposomes includes integrating a channel protein into the lipid bilayer membrane (see, e.g., Non-Patent Document 8: Ranquin A, Versees W, Miere W, Steyaert J, Gelder PV., “Therapeutic Nanoreactors: Combining Chemistry and Biology in a Novel Triblock Copolymer”, Drug Delivery System, Nano Lett., 2005, 5:2220-4). However, this method is not practical either, since the process is cumbersome and complicated and lacks versatality.
Thus, there is a demand for a process of easily and efficiently producing a substance-encapsulating vesicle, in which a substance is encapsulated in the cavity of a vesicle formed via self-assembly of polymers.
With regard to vacant vesicles for encapsulating and carrying an active ingredient in the vesicle cavity, there is still room for improvement in the stability of carriage. In addition, it is still difficult to make two or more active ingredients carried by such a vesicle.
Thus, there is a demand for developing a new vesicle which can carry an active ingredient with improved stability, and can also carry two or more ingredients with improved controllability.
Scope of claims [claim1]
1. A vesicle formed via self-assembly comprising a membrane containing:
a block copolymer having an uncharged hydrophilic segment and a cationic segment; and
a nucleic acid;
said membrane defining a cavity surrounded thereby,
wherein the membrane has a trilaminar structure comprising an outer layer formed with the uncharged hydrophilic segment, an intermediate layer formed via electrostatic binding between the cationic segment and the nucleic acid, and an inner layer formed with the uncharged hydrophilic segment.

[claim2]
2. The vesicle according to claim 1, which has an N+/P ratio of higher than 1.0 and lower than 3.0, the N+/P ratio being a mole ratio of cationic groups of the cationic segment to phosphate groups of the nucleic acid.

[claim3]
3. The vesicle according to claim 1, wherein the uncharged hydrophilic segment is polyalkylene glycol.

[claim4]
4. The vesicle according to claim 1, wherein the cationic segment is polyamine.

[claim5]
5. The vesicle according to claim 1, wherein the membrane further comprises a cross-linker.

[claim6]
6. The vesicle according to claim 5, which has a CL/N ratio of 0.1 or higher, the CL/N ratio being a mole ratio of the cross-linker to cationic groups of the cationic segment.

[claim7]
7. The vesicle according to claim 5, wherein the cross-linker is glutaraldehyde.

[claim8]
8. The vesicle according to claim 1, for use in a drug delivery system.

[claim9]
9. A drug delivery system comprising:
a vesicle according to claim 1; and
a charged substance encapsulated in the cavity of the vesicle.
  • Inventor, and Inventor/Applicant
  • Kataoka Kazunori
  • Kishimura Akihiro
  • Anraku Yasutaka
  • Miyata Kanjiro
  • Chuanoi Sayan
  • Suma Tomoya
  • Oba Makoto
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
IPC(International Patent Classification)
Reference ( R and D project ) CREST Establishment of Innovative Manufacturing Technology Based on Nanoscience AREA
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