From molecular bridge to macro-encapsulation: Unraveling the HEPES-porosity synergy for ultra-high peptide loading in PLGA microspheres.
4 affiliations
- 1State Key Laboratory of National Security Specially Needed Medicines, Beijing, 100039, China.
- 2Academy of Military Medical Sciences, Beijing, 100850, China.
- 3School of Pharmacy, Qingdao University, Qingdao, 266071, China.
- 4Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
Abstract
The clinical translation of long-acting peptide-loaded microspheres is often hampered by low and unpredictable encapsulation efficiency (EE), stemming from the complex interplay among formulation parameters. This study clarified these interactions by establishing a holistic, mechanism-guided framework that integrated polymer chemistry, matrix microstructure, and the incubation microenvironment. Using leuprolide acetate as a model peptide, we systematically deconstructed the key determinants of EE in a self-healing poly(lactic-co-glycolic acid) (PLGA) microsphere system. We found that the terminal carboxyl content of PLGA was a major determinant of peptide-polymer binding affinity, while the engineered pore architecture balanced peptide accessibility and retention and modulated loading-associated peptide-polymer interactions. Crucially, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) provided a more favorable loading environment than phosphate-buffered saline or Tris(hydroxymethyl)aminomethane hydrochloride and promoted peptide-PLGA association. Convergent experimental and simulation evidence supported a proposed HEPES-mediated non-covalent ternary association among leuprolide, HEPES, and PLGA. Optimization of the HEPES concentration and self-healing conditions further enhanced peptide-polymer association and encapsulation. Applying these findings, we fabricated optimized leuprolide-loaded microspheres with an EE of 96.44% and a drug loading of 9.64%, which were higher than the reported EE and drug-loading values for Lupron DepotⓇ. The applicability of this formulation framework beyond the leuprolide acetate formulation was further supported by the high EEs achieved for two additional cationic peptides, triptorelin acetate (90.26%) and octreotide acetate (91.04%). This work provides a rational, multi-parameter formulation framework for improving the encapsulation of selected cationic peptides in self-healing PLGA microspheres by integrating mechanistic evidence with pharmaceutical formulation design.
Related
- Unraveling Trimethoprim-Sulfonamide synergy against Escherichia coli through semi-mechanistic PK/PD modeling
- Unraveling the multitarget mechanisms of aloe emodin against periodontitis: a synergy of network pharmacology and experimental validation
- Molecular insights into skin pigmentation: Unraveling the role of key genes and miRNAs in melanogenesis
- Unraveling the therapeutic mechanisms of placenta hominis for polycystic ovary syndrome through network pharmacology, molecular docking, and experimental validation
- Clinic-to-Mechanism: Unraveling in-depth molecular dysfunctions caused by a GluN2B C-Terminal deletion in developmental and epileptic encephalopathies
BibTeX
@article{bai2026from,
title = {{From molecular bridge to macro-encapsulation: Unraveling the HEPES-porosity synergy for ultra-high peptide loading in PLGA microspheres.}},
author = {Jiahui Bai and Shan Wang and Ke Li and Jingyu Cui and Zhuang Liu and Yang Zhang and Bo Ma and Zhiping Li and Jing Gao},
journal = {Asian journal of pharmaceutical sciences},
year = {2026},
month = oct,
doi = {10.1016/j.ajps.2026.101206},
url = {https://europepmc.org/article/MED/42997591},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - From molecular bridge to macro-encapsulation: Unraveling the HEPES-porosity synergy for ultra-high peptide loading in PLGA microspheres.
AU - Jiahui Bai
AU - Shan Wang
AU - Ke Li
AU - Jingyu Cui
AU - Zhuang Liu
AU - Yang Zhang
AU - Bo Ma
AU - Zhiping Li
AU - Jing Gao
PY - 2026
DA - 2026/10/15
JO - Asian journal of pharmaceutical sciences
DO - 10.1016/j.ajps.2026.101206
UR - https://europepmc.org/article/MED/42997591
AB - The clinical translation of long-acting peptide-loaded microspheres is often hampered by low and unpredictable encapsulation efficiency (EE), stemming from the complex interplay among formulation parameters. This study clarified these interactions by establishing a holistic, mechanism-guided framework that integrated polymer chemistry, matrix microstructure, and the incubation microenvironment. Using leuprolide acetate as a model peptide, we systematically deconstructed the key determinants of EE in a self-healing poly(lactic-co-glycolic acid) (PLGA) microsphere system. We found that the terminal carboxyl content of PLGA was a major determinant of peptide-polymer binding affinity, while the engineered pore architecture balanced peptide accessibility and retention and modulated loading-associated peptide-polymer interactions. Crucially, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) provided a more favorable loading environment than phosphate-buffered saline or Tris(hydroxymethyl)aminomethane hydrochloride and promoted peptide-PLGA association. Convergent experimental and simulation evidence supported a proposed HEPES-mediated non-covalent ternary association among leuprolide, HEPES, and PLGA. Optimization of the HEPES concentration and self-healing conditions further enhanced peptide-polymer association and encapsulation. Applying these findings, we fabricated optimized leuprolide-loaded microspheres with an EE of 96.44% and a drug loading of 9.64%, which were higher than the reported EE and drug-loading values for Lupron DepotⓇ. The applicability of this formulation framework beyond the leuprolide acetate formulation was further supported by the high EEs achieved for two additional cationic peptides, triptorelin acetate (90.26%) and octreotide acetate (91.04%). This work provides a rational, multi-parameter formulation framework for improving the encapsulation of selected cationic peptides in self-healing PLGA microspheres by integrating mechanistic evidence with pharmaceutical formulation design.
SN - 1818-0876
SN - 2221-285X
ER -