Novel Random Triblock Copolymers for Sustained Delivery of Macromolecules for the Treatment of Ocular Diseases

  • Mary Joseph Ngatuni
  • Hoang M. Trinh
  • Dhananjay Pal
  • Ashim K. Mitra
Research Article


The objective of this study is to design, develop, and synthesize novel random triblock (RTB) copolymers for sustained delivery of macromolecules. RTB copolymers have not been utilized for the delivery of macromolecules for ocular diseases. RTB copolymers comprising of polyethylene glycol, glycolide, and ɛ-caprolactone blocks were synthesized and assessed for their molecular weights and purity using 1H-NMR spectroscopy, gel permeation chromatography, FTIR (functionality), and XRD (crystallinity). No toxicity was observed when ocular cell lines were treated with RTB copolymers. These materials were applied for encapsulation of peptides and proteins (catalase, IgG, BSA, IgG Fab fragment, lysozyme, insulin, and octreotide) in nanoparticles. Particle size ranged from 202.41 ± 2.45 to 300.1 ± 3.11 nm depending on the molecular size and geometry of proteins/peptides. Polydispersity indices were between 0.26 ± 0.02 and 0.46 ± 0.07 respectively. Percentage entrapment efficiency and drug loading ranged from 83.44 ± 2.24 to 45.35 ± 5.53 and 21.56 ± 0.46 to 13.08 ± 1.35 respectively depending on molecular weights of peptides or proteins. A sustained in vitro release of macromolecule was observed over 3-month period. These results suggest that RTB copolymers may be suitable for sustained delivery systems for various macromolecules for different diseases including ocular diseases.


random triblock copolymers nanoparticles ocular delivery protein and peptide sustained drug delivery controlled release 



The authors would like to thank Dr. James Murowchick (Department of Geosciences, UMKC) for XRD analysis, Dr. Zhonghua Peng (Department of Chemistry, UMKC) for his assistance in GPC analysis, and Dr. Kun Cheng (Department of Pharmaceutical Sciences, UMKC) for allowing us to utilize freeze dryer.

Funding Information

This work was supported by National Institute of Health grants RO1 EY 09171-14, RO1 EY 10659-12, and Genentech. This work is also financially supported by Graduate Assistant Fund (GAF), UMKC Women’s Council.

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.


  1. 1.
    Penn JS, Madan A, Caldwell RB, Bartoli M, Caldwell RW, Hartnett ME. Vascular endothelial growth factor in eye disease. Prog Retin Eye Res. 2008;27(4):331–71.CrossRefGoogle Scholar
  2. 2.
    Krock BL, Skuli N, Simon MC. Hypoxia-induced angiogenesis: good and evil. Genes Cancer. 2011;2(12):1117–33.CrossRefGoogle Scholar
  3. 3.
    Vadlapatla RK, Vadlapudi AD, Mitra AK. Hypoxia-inducible factor-1 (HIF-1): a potential target for intervention in ocular neovascular diseases. Curr Drug Targets. 2013;14(8):919–35.CrossRefGoogle Scholar
  4. 4.
    Qazi Y, Maddula S, Ambati BK. Mediators of ocular angiogenesis. J Genet. 2009;88(4):495–515.CrossRefGoogle Scholar
  5. 5.
    Stewart MW. The expanding role of vascular endothelial growth factor inhibitors in ophthalmology. Mayo Clin Proc. 2012;87(1):77–88.CrossRefGoogle Scholar
  6. 6.
    Relhan N, Flynn HW Jr. The Early Treatment Diabetic Retinopathy Study historical review and relevance to today’s management of diabetic macular edema. Curr Opin Ophthalmol. 2017;28:205–12.CrossRefGoogle Scholar
  7. 7.
    Boyer DS, Hopkins JJ, Sorof J, Ehrlich JS. Anti-vascular endothelial growth factor therapy for diabetic macular edema. Ther Adv Endocrinol Metab. 2013;4(6):151–69.CrossRefGoogle Scholar
  8. 8.
    Falavarjani KG, Nguyen QD. Adverse events and complications associated with intravitreal injection of anti-VEGF agents: a review of literature. Eye (Lond). 2013;27(7):787–94.CrossRefGoogle Scholar
  9. 9.
    Gaudana R, Ananthula HK, Parenky A, Mitra AK. Ocular drug delivery. AAPS J. 2010;12(3):348–60.CrossRefGoogle Scholar
  10. 10.
    Joseph M, Trinh HM, Cholkar K, Pal D, Mitra AK. Recent perspectives on the delivery of biologics to back of the eye. Expert Opin Drug Deliv. 2017;14(5)631–45.CrossRefGoogle Scholar
  11. 11.
    Moisseiev E, Waisbourd M, Ben-Artsi E, Levinger E, Barak A, Daniels T, et al. Pharmacokinetics of bevacizumab after topical and intravitreal administration in human eyes. Graefes Arch Clin Exp Ophthalmol. 2014;252(2):331–7.CrossRefGoogle Scholar
  12. 12.
    Xu L, Lu T, Tuomi L, Jumbe N, Lu J, Eppler S, et al. Pharmacokinetics of ranibizumab in patients with neovascular age-related macular degeneration: a population approach. Invest Ophthalmol Vis Sci. 2013;54(3):1616–24.CrossRefGoogle Scholar
  13. 13.
    Shikari H, Silva PS, Sun JK. Complications of intravitreal injections in patients with diabetes. Semin Ophthalmol. 2014;29(5–6):276–89.CrossRefGoogle Scholar
  14. 14.
    Solaro R, Chiellini F, Battisti A. Targeted delivery of protein drugs by nanocarriers. Materials. 2010;3(3):1928–80.CrossRefGoogle Scholar
  15. 15.
    Jiang Z, Hao J, You Y, Gu Q, Cao W, Deng X. Biodegradable thermogelling hydrogel of P(CL-GL)-PEG-P(CL-GL) triblock copolymer: degradation and drug release behavior. J Pharm Sci. 2009;98(8):2603–10.CrossRefGoogle Scholar
  16. 16.
    Jiang Z, You Y, Deng X, Hao J. Injectable hydrogels of poly(ɛ-caprolactone-co-glycolide)–poly(ethylene glycol)–poly(ɛ-caprolactone-co-glycolide) triblock copolymer aqueous solutions. Polymer. 2007;48(16):4786–92.CrossRefGoogle Scholar
  17. 17.
    Patel SP, Vaishya R, Mishra GP, Tamboli V, Pal D, Mitra AK. Tailor-made pentablock copolymer based formulation for sustained ocular delivery of protein therapeutics. J Drug Deliv 2014;2014:401747, 1, 15.CrossRefGoogle Scholar
  18. 18.
    Patel SP, Vaishya R, Yang X, Pal D, Mitra AK. Novel thermosensitive pentablock copolymers for sustained delivery of proteins in the treatment of posterior segment diseases. Protein Pept Lett. 2014;21(11):1185–200.CrossRefGoogle Scholar
  19. 19.
    Agrahari V, Agrahari V, Hung WT, Christenson LK, Mitra AK. Composite nanoformulation therapeutics for long-term ocular delivery of macromolecules. Mol Pharm. 2016;13(9):2912–22.CrossRefGoogle Scholar
  20. 20.
    Patel SP, Vaishya R, Patel A, Agrahari V, Pal D, Mitra AK. Optimization of novel pentablock copolymer based composite formulation for sustained delivery of peptide/protein in the treatment of ocular diseases. J Microencapsul. 2016;33(2):103–13.CrossRefGoogle Scholar
  21. 21.
    Patel A, Gaudana R, Mitra AK. A novel approach for antibody nanocarriers development through hydrophobic ion-pairing complexation. J Microencapsul. 2014;31(6):542–50.CrossRefGoogle Scholar
  22. 22.
    Panyam J, Dali MM, Sahoo SK, Ma W, Chakravarthi SS, Amidon GL, et al. Polymer degradation and in vitro release of a model protein from poly(D,L-lactide-co-glycolide) nano- and microparticles. J Control Release. 2003;92(1–2):173–87.CrossRefGoogle Scholar
  23. 23.
    Dash S, Murthy PN, Nath L, Chowdhury P. Kinetic modeling on drug release from controlled drug delivery systems. Acta Pol Pharm. 2010;67(3):217–23.PubMedGoogle Scholar
  24. 24.
    Fu Y, Kao WJ. Drug release kinetics and transport mechanisms of non-degradable and degradable polymeric delivery systems. Expert Opin Drug Deliv. 2010;7(4):429–44.CrossRefGoogle Scholar
  25. 25.
    Alibolandi M, Sadeghi F, Sazmand SH, Shahrokhi SM, Seifi M, Hadizadeh F. Synthesis and self-assembly of biodegradable polyethylene glycol-poly (lactic acid) diblock copolymers as polymersomes for preparation of sustained release system of doxorubicin. Int J Pharm Investig. 2015;5(3):134–41.CrossRefGoogle Scholar
  26. 26.
    Jokerst JV, Lobovkina T, Zare RN, Gambhir SS. Nanoparticle PEGylation for imaging and therapy. Nanomedicine (Lond). 2011;6(4):715–28.CrossRefGoogle Scholar
  27. 27.
    Xiao RZ, Zeng ZW, Zhou GL, Wang JJ, Li FZ, Wang AM. Recent advances in PEG-PLA block copolymer nanoparticles. Int J Nanomedicine. 2010;5:1057–65.PubMedPubMedCentralGoogle Scholar
  28. 28.
    Dziadek M, Pawlik J, Menaszek E, Stodolak-Zych E, Cholewa-Kowalska K. Effect of the preparation methods on architecture, crystallinity, hydrolytic degradation, bioactivity, and biocompatibility of PCL/bioglass composite scaffolds. J Biomed Mater Res B Appl Biomater. 2015;103(8):1580–93.CrossRefGoogle Scholar
  29. 29.
    Patel SP, Vaishya R, Pal D, Mitra AK. Novel pentablock copolymer-based nanoparticulate systems for sustained protein delivery. AAPS PharmSciTech. 2015;16(2):327–43.CrossRefGoogle Scholar
  30. 30.
    Huang M-H, Li S, Vert M. Synthesis and degradation of PLA–PCL–PLA triblock copolymer prepared by successive polymerization of ε-caprolactone and dl-lactide. Polymer. 2004;45(26):8675–81.CrossRefGoogle Scholar
  31. 31.
    Vaishya RD, Mandal A, Patel S, Mitra AK. Extended release microparticle-in-gel formulation of octreotide: effect of polymer type on acylation of peptide during in vitro release. Int J Pharm. 2015;496(2):676–88.CrossRefGoogle Scholar
  32. 32.
    Singh R, Lillard JW Jr. Nanoparticle-based targeted drug delivery. Exp Mol Pathol. 2009;86(3):215–23.CrossRefGoogle Scholar
  33. 33.
    Venkatesh P, Chawla R, Shah B, Garg SP. Surprises during intravitreal drug delivery-a report of three cases. Digit J Ophthalmol. 2017;23(1):33–5.CrossRefGoogle Scholar
  34. 34.
    Thassu D, Deleers M, Pathak Y. Nanoparticulate drug delivery systems. New York: Informa Healthcare; 2007. x, 352 p., 8 p. of plates pCrossRefGoogle Scholar
  35. 35.
    Tamboli V, Mishra GP, Mitra AK. Novel pentablock copolymer (PLA-PCL-PEG-PCL-PLA) based nanoparticles for controlled drug delivery: effect of copolymer compositions on the crystallinity of copolymers and in vitro drug release profile from nanoparticles. Colloid Polym Sci. 2013;291(5):1235–45.CrossRefGoogle Scholar
  36. 36.
    Wang W. Protein aggregation and its inhibition in biopharmaceutics. Int J Pharm. 2005;289(1–2):1–30.CrossRefGoogle Scholar
  37. 37.
    Kim HK, Park TG. Microencapsulation of human growth hormone within biodegradable polyester microspheres: protein aggregation stability and incomplete release mechanism. Biotechnol Bioeng. 1999;65(6):659–67.CrossRefGoogle Scholar
  38. 38.
    Jawahar N, Meyyanathan SN. Polymeric nanoparticles for drug delivery and targeting: a comprehensive review. Int J Health Allied Sci. 2012;1:217–23. Available from: Scholar
  39. 39.
    Arifin DY, Lee LY, Wang CH. Mathematical modeling and simulation of drug release from microspheres: implications to drug delivery systems. Adv Drug Deliv Rev. 2006;58(12–13):1274–325.CrossRefGoogle Scholar
  40. 40.
    Kumar R, Sinha VR. Lipid nanocarrier: an efficient approach towards ocular delivery of hydrophilic drug (Valacyclovir). AAPS PharmSciTech. 2016.CrossRefGoogle Scholar
  41. 41.
    Kumar R, Nagarwal RC, Dhanawat M, Pandit JK. In-vitro and in-vivo study of indomethacin loaded gelatin nanoparticles. J Biomed Nanotechnol. 2011;7(3):325–33.CrossRefGoogle Scholar

Copyright information

© American Association of Pharmaceutical Scientists 2018

Authors and Affiliations

  • Mary Joseph Ngatuni
    • 1
  • Hoang M. Trinh
    • 1
  • Dhananjay Pal
    • 1
  • Ashim K. Mitra
    • 1
  1. 1.Division of Pharmaceutical Sciences, School of PharmacyUniversity of Missouri-Kansas CityKansas CityUSA

Personalised recommendations