Synthesis and characterisation of bio-inspired polymers for pH-mediated intracellular delivery and therapeutic applications
File(s)
Author(s)
Cui, Jiawei
Type
Thesis
Abstract
Effective intracellular delivery remains a significant challenge in the development of non-viral delivery systems. Endosomal entrapment, which results in enzymatic degradation of bioactive compounds in lysosomes, is one of the main barriers. This thesis outlines endeavours to develop biomimetic nanoscale systems tailored for pH-triggered intracellular delivery.
A library of innovative pH-responsive polymers was developed to mimic fusogenic viral peptides. They were synthesized by grafting fatty acids to the pendant carboxyl groups along the backbone of the pseudopeptide poly (L-lysine iso-phthalamide) (PLP) at varying degrees of grafting. The effects of hydrophobic chains on pH-responsive properties in aqueous solution, cell membrane destabilization activity, and in vitro cytotoxicity were examined. The synthesized and characterized 12-aminododecanoic acid-grafted PLP (PLP-ADA) exhibited minimal cytotoxicity toward different mammalian cell lines. The polymer-mediated translocation of model payloads into cells was demonstrated. The mechanism behind membrane destabilization was elucidated, showing the superior endosomal-escape ability of the polymer to release endocytosed materials into the cytoplasm. Under mildly acidic extracellular conditions, its intracellular delivery was significantly enhanced. The thesis systematically explores the effects of side chain, polymer concentration, treatment time, extracellular pH, and payload size on delivery efficiency across various cell types, demonstrating its broad applicability in drug delivery. Furthermore, PLP-ADA has shown the capability to enhance the internalization of the ribosome-inactivating protein Saporin, inducing cell death in cancer cells, suggesting its potential for cancer therapy applications.
In addition, the optimal pH-responsive polymer was utilized to facilitate intracellular loading of membrane-impermeable trehalose for cryoprotection of mammalian cells. This could avoid the use of toxic dimethyl sulfoxide (DMSO). With the assistance of PLP-ADA, efficient delivery of trehalose into red blood cells (RBCs) and an immortalized line Jurkat cells was achieved. The successful cryopreservation of cells was demonstrated, which addresses a crucial aspect in emerging fields of cell therapy and biobanking.
A library of innovative pH-responsive polymers was developed to mimic fusogenic viral peptides. They were synthesized by grafting fatty acids to the pendant carboxyl groups along the backbone of the pseudopeptide poly (L-lysine iso-phthalamide) (PLP) at varying degrees of grafting. The effects of hydrophobic chains on pH-responsive properties in aqueous solution, cell membrane destabilization activity, and in vitro cytotoxicity were examined. The synthesized and characterized 12-aminododecanoic acid-grafted PLP (PLP-ADA) exhibited minimal cytotoxicity toward different mammalian cell lines. The polymer-mediated translocation of model payloads into cells was demonstrated. The mechanism behind membrane destabilization was elucidated, showing the superior endosomal-escape ability of the polymer to release endocytosed materials into the cytoplasm. Under mildly acidic extracellular conditions, its intracellular delivery was significantly enhanced. The thesis systematically explores the effects of side chain, polymer concentration, treatment time, extracellular pH, and payload size on delivery efficiency across various cell types, demonstrating its broad applicability in drug delivery. Furthermore, PLP-ADA has shown the capability to enhance the internalization of the ribosome-inactivating protein Saporin, inducing cell death in cancer cells, suggesting its potential for cancer therapy applications.
In addition, the optimal pH-responsive polymer was utilized to facilitate intracellular loading of membrane-impermeable trehalose for cryoprotection of mammalian cells. This could avoid the use of toxic dimethyl sulfoxide (DMSO). With the assistance of PLP-ADA, efficient delivery of trehalose into red blood cells (RBCs) and an immortalized line Jurkat cells was achieved. The successful cryopreservation of cells was demonstrated, which addresses a crucial aspect in emerging fields of cell therapy and biobanking.
Version
Open Access
Date Issued
2024-05-30
Date Awarded
01/09/2024
License URL
Advisor
Chen, Rongjun
Publisher Department
Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)