. 2016 Nov 16;8(11):397.

doi: 10.3390/polym8110397.

Co-Delivery of Imiquimod and Plasmid DNA via an Amphiphilic pH-Responsive Star Polymer that Forms Unimolecular Micelles in Water

Wenjing Lin^{1

2}, Na Yao³, Hongru Li^{4

5}, Samuel Hanson⁶, Wenqing Han⁷, Chun Wang⁸, Lijuan Zhang⁹

Affiliations

¹ School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China. lin.wenjing@mail.scut.edu.cn.
² Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. lin.wenjing@mail.scut.edu.cn.
³ School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China. yao.na@mail.scut.edu.cn.
⁴ Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. lihongru@nankai.edu.cn.
⁵ State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, College of Pharmacy, Nankai University, Tianjin 300071, China. lihongru@nankai.edu.cn.
⁶ Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. hans3689@umn.edu.
⁷ Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. hanxx144@umn.edu.
⁸ Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. wangx504@umn.edu.
⁹ School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China. celjzh@scut.edu.cn.

PMID: 30974677
PMCID: PMC6431966
DOI: 10.3390/polym8110397

Co-Delivery of Imiquimod and Plasmid DNA via an Amphiphilic pH-Responsive Star Polymer that Forms Unimolecular Micelles in Water

Wenjing Lin et al. Polymers (Basel). 2016.

. 2016 Nov 16;8(11):397.

doi: 10.3390/polym8110397.

Authors

Wenjing Lin^{1

2}, Na Yao³, Hongru Li^{4

5}, Samuel Hanson⁶, Wenqing Han⁷, Chun Wang⁸, Lijuan Zhang⁹

Affiliations

¹ School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China. lin.wenjing@mail.scut.edu.cn.
² Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. lin.wenjing@mail.scut.edu.cn.
³ School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China. yao.na@mail.scut.edu.cn.
⁴ Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. lihongru@nankai.edu.cn.
⁵ State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, College of Pharmacy, Nankai University, Tianjin 300071, China. lihongru@nankai.edu.cn.
⁶ Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. hans3689@umn.edu.
⁷ Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. hanxx144@umn.edu.
⁸ Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. wangx504@umn.edu.
⁹ School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China. celjzh@scut.edu.cn.

PMID: 30974677
PMCID: PMC6431966
DOI: 10.3390/polym8110397

Abstract

Dual functional unimolecular micelles based on a pH-responsive amphiphilic star polymer β-CD-(PLA-b-PDMAEMA-b-PEtOxMA)₂₁ have been developed for the co-delivery of imiquimod and plasmid DNA to dendritic cells. The star polymer with well-defined triblock arms was synthesized by combining activator regenerated by electron-transfer atom-transfer radical polymerization with ring-opening polymerization. Dissipative particle dynamics simulation showed that core-mesophere-shell-type unimolecular micelles could be formed. Imiquimod-loaded micelles had a drug loading of 1.6 wt % and a larger average size (28 nm) than blank micelles (19 nm). The release of imiquimod in vitro was accelerated at the mildly acidic endolysosomal pH (5.0) in comparison to physiologic pH (7.4). Compared with blank micelles, a higher N:P ratio was required for imiquimod-loaded micelles to fully condense DNA into micelleplexes averaging 200⁻400 nm in size. In comparison to blank micelleplexes, imiquimod-loaded micelleplexes of the same N:P ratio displayed similar or slightly higher efficiency of gene transfection in a mouse dendritic cell line (DC2.4) without cytotoxicity. These results suggest that such pH-responsive unimolecular micelles formed by the well-defined amphiphilic star polymer may serve as promising nano-scale carriers for combined delivery of hydrophobic immunostimulatory drugs (such as imiquimod) and plasmid DNA with potential application in gene-based immunotherapy.

Keywords: co-delivery; immunotherapy; pH-responsive; unimolecular micelles.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

**Scheme 1**
Schematic illustration of co-delivery of IMQ (red triangles) and plasmid DNA to dendritic cells via unimolecular micelles formed by the amphiphilic pH-responsive star polymer β-CD-(PLA-b-PDMAEMA-b-PEtOxMA)₂₁.

**Scheme 2**
Schematic illustration of the synthesis of β-CD-(PLA-b-PDMAEMA-b-PEtOxMA)₂₁.

**Figure 1**
The complete conversion of 21 hydroxyl groups of pristine β-CD to PLA arms. (A) ¹H NMR spectra of β-CD in DMSO-d₆ and β-CD-(PCL-OH)₂₁ in CDCl₃; (B) FT IR spectra of β-CD and β-CD-(PCL-OH)₂₁.

**Figure 2**
¹H NMR spectra of β-CD-(PLA-OH)₂₁ (A); β-CD-(PLA-Br)₂₁ (B); β-CD-(PLA-b-PDMAEMA)₂₁ (C); and β-CD-(PLA-b-PDMAEMA-b-PEtOxMA)₂₁ (D) in CDCl₃.

**Figure 3**
Intensity of the fluorescence emission of Nile red at 620 nm (λ_ex = 550 nm; slit widths: Ex. 5 nm, Em. 5 nm) as a function of concentration of β-CD-(PLA-b-PDMAEMA-b-PEtOxMA)₂₁ as well as an expanded view of the low concentration range (inset).

**Figure 4**
DPD simulation of β-CD-(PLA-b-PDMAEMA-b-PEtOxMA)₂₁ at different simulation times at experimental concentration of 0.1 mg/mL. (A) Formation process. (B) Radius of gyration of EtOxMA, DMAEMA, and d,l-LA.

**Figure 5**
DLS plots (A,C) and TEM images (B,D, discrete and spherical blackspots) of blank (A,B) and IMQ-loaded (C,D) β-CD-(PLA-b-PDMAEMA-b-PEtOxMA)₂₁ micelles.

**Figure 6**
Enhancement of solubility and accelerated release of IMQ through encapsulation in β-CD-(PLA-b-PDMAEMA-b-PEtOxMA)₂₁ unimolecular micelles. (A) UV spectra of the IMQ-loaded micelles solution, water-IMQ solution, and blank micelle solution, pH 7.4; (B) In vitro release profiles of IMQ from micelles at pH 7.4 and 5.0.

**Figure 7**
DNA binding, condensation by micelles, and size and morphology of micelleplexes with or without loading of IMQ. (A) Gel retardation assay; (B) ethidium bromide (EB) exclusion; (C) average particle size by DLS; TEM images of blank micelleplexes (D); and IMQ-loaded micelleplexes (E) at N:P = 20 (The discrete and spherical blackspots represented corresponding micelleplexes).

**Figure 8**
Transfection efficiency of DC2.4 cells by micelleplexes determined by flow cytometry. Quantification by the percentage of transfected GFP⁺ cells (A) and mean fluorescence intensity (B). * p < 0.05.

See this image and copyright information in PMC

References

1. Singh M., O’Hagan D. Advances in vaccine adjuvants. Nat. Biotechnol. 1999;17:1075–1081. doi: 10.1038/15058. - DOI - PubMed
1. O’Hagan D.T., Valiante N.M. Recent advances in the discovery and delivery of vaccine adjuvants. Nat. Rev. Drug Discov. 2003;2:727–735. doi: 10.1038/nrd1176. - DOI - PMC - PubMed
1. Reed S.G., Bertholet S., Coler R.N., Friede M. New horizons in adjuvants for vaccine development. Trends Immunol. 2009;30:23–32. doi: 10.1016/j.it.2008.09.006. - DOI - PubMed
1. Alving C.R., Peachman K.K., Rao M., Reed S.G. Adjuvants for human vaccines. Curr. Opin. Immunol. 2012;24:310–315. doi: 10.1016/j.coi.2012.03.008. - DOI - PMC - PubMed
1. Mbow M.L., De Gregorio E., Valiante N.M., Rappuoli R. New adjuvants for human vaccines. Curr. Opin. Immunol. 2010;22:411–416. doi: 10.1016/j.coi.2010.04.004. - DOI - PubMed

Grants and funding

LinkOut - more resources

Full Text Sources
Other Literature Sources
- The Lens - Patent Citations Database

Save citation to file

Email citation

Add to Collections

Add to My Bibliography

Your saved search

Create a file for external citation management software

Your RSS Feed

Co-Delivery of Imiquimod and Plasmid DNA via an Amphiphilic pH-Responsive Star Polymer that Forms Unimolecular Micelles in Water

Affiliations

Co-Delivery of Imiquimod and Plasmid DNA via an Amphiphilic pH-Responsive Star Polymer that Forms Unimolecular Micelles in Water

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

References

Grants and funding

LinkOut - more resources

Full Text Sources

Other Literature Sources