39 research outputs found
Can Flory-Stockmayer theory be applied to predict conventional free radical polymerization of multivinyl monomers:a study via Monte Carlo simulations
Hyperbranched PEG-based multi-NHS polymer and bioconjugation with BSA
Star-shaped poly(ethylene glycol)-N-hydroxysuccinimide (star- PEG-NHS) has shown great promise in a variety of biomedical applications owing to its non-toxicity, innate non-immunogenic properties and versatile, multifunctional end groups. However, its complex and sophisticated synthetic methods, as well as high costs, have significantly impeded its wide application. Here, we report the design and synthesis of a hyperbranched PEG-based polymer with multiple NHS functional groups (>12). The hyper- branched PEG-based multi-NHS polymer can react easily with a protein (bovine serum albumin, BSA) to form a PEG-protein hydro- gel that displays great potential for biomedical applications
Highly Branched Poly(5-amino-1-pentanol-co-1,4- butanediol diacrylate) for High Performance Gene Transfection
The top-performing linear poly(β-amino ester) (LPAE), poly(5-amino-1-pentanol-co-1,4-butanediol diacrylate) (C32), has demonstrated gene transfection efficiency comparable to viral-mediated gene delivery. Herein, we report the synthesis of a series of highly branched poly(5-amino-1-pentanol-co-1,4-butanediol diacrylate) (HC32) and explore how the branching structure influences the performance of C32 in gene transfection. HC32 were synthesized by an “A2 + B3 + C2” Michal addition strategy. Gaussia luciferase (Gluciferase) and green fluorescent protein (GFP) coding plasmid DNA were used as reporter genes and the gene transfection efficiency was evaluated in human cervical cancer cell line (HeLa) and human recessive dystrophic epidermolysis bullosa keratinocyte (RDEBK) cells. We found that the optimal branching structure led to a much higher gene transfection efficiency in comparison to its linear counterpart and commercial reagents, while preserving high cell viability in both cell types. The branching strategy affected DNA binding, proton buffering capacity and degradation of polymers as well as size, zeta potential, stability, and DNA release rate of polyplexes significantly. Polymer degradation and DNA release rate played pivotal parts in achieving the high gene transfection efficiency of HC32-103 polymers, providing new insights for the development of poly(β-amino ester)s-based gene delivery vectors
Highly Branched Poly(5-amino-1-pentanol-co-1,4-butanediol diacrylate) for High Performance Gene Transfection
The top-performing linear poly(β-amino ester) (LPAE), poly(5-amino-1-pentanol-co-1,4-butanediol diacrylate) (C32), has demonstrated gene transfection efficiency comparable to viral-mediated gene delivery. Herein, we report the synthesis of a series of highly branched poly(5-amino-1-pentanol-co-1,4-butanediol diacrylate) (HC32) and explore how the branching structure influences the performance of C32 in gene transfection. HC32 were synthesized by an “A2 + B3 + C2” Michal addition strategy. Gaussia luciferase (Gluciferase) and green fluorescent protein (GFP) coding plasmid DNA were used as reporter genes and the gene transfection efficiency was evaluated in human cervical cancer cell line (HeLa) and human recessive dystrophic epidermolysis bullosa keratinocyte (RDEBK) cells. We found that the optimal branching structure led to a much higher gene transfection efficiency in comparison to its linear counterpart and commercial reagents, while preserving high cell viability in both cell types. The branching strategy affected DNA binding, proton buffering capacity and degradation of polymers as well as size, zeta potential, stability, and DNA release rate of polyplexes significantly. Polymer degradation and DNA release rate played pivotal parts in achieving the high gene transfection efficiency of HC32-103 polymers, providing new insights for the development of poly(β-amino ester)s-based gene delivery vectors
A hybrid injectable hydrogel from hyperbranched PEG macromer as a stem cell delivery and retention platform for diabetic wound healing
Monte Carlo Simulations of Atom Transfer Radical (Homo)polymerization of Divinyl Monomers: Applicability of Flory–Stockmayer Theory
It
is well known that free radical (co)Âpolymerization of multivinyl
monomers (MVMs) leads to insoluble gels even at a low monomer conversion,
and the gelation point can be predicted by Flory–Stockmayer
theory (F–S theory) based on two assumptions: (1) equal reactivity
of all vinyl groups and (2) the absence of intramolecular cyclization.
This theory has been experimentally studied and verified with conventional
free radical (co)Âpolymerization (FRP) of several MVMs (e.g., divinylbenzene,
DVB). However, it is still debatable whether this theory is applicable
for the polymerization of MVMs using reversible deactivation radical
polymerization (RDRP) approaches, such as atom transfer radical polymerization
(ATRP). Herein, Monte Carlo simulations using two statistical modelsî—¸with
cyclization (<b>w.c.</b>) and without cyclization (<b>wo.c.</b>, corresponding to F–S theory)and dynamic lattice
liquid (DLL) models were conducted to study ATRP of divinyl monomers.
The simulated gel points using <b>w.c.</b> and <b>wo.c.</b> models were compared with those obtained from ATRP experiments,
from calculation using F–S theory, and from simulations using
DLL models. The molecular weights, dispersity, and extent of intermolecular/intramolecular
cross-linking were calculated as a function of double bond and cross-linker
conversion. The results demonstrated that the gel points obtained
from both <b>w.c.</b> and <b>wo.c.</b> models were lower
than the values from DLL models and experiments. This indicates that
F–S theory cannot be used to accurately predict the polymerization
of divinyl monomers via ATRP. Our study shows that the limitation
of F–S theory in predicting ATRP reaction of divinyl monomers
is not only due to neglecting intramolecular cyclization but also
due to spatial restrictions which can cause the reactivity and accessibility
of vinyl groups becoming nonequivalent in ATRP of divinyl monomers
Highly branched poly(β-amino ester) delivery of minicircle DNA for transfection of neurodegenerative disease related cells
Current therapies for most neurodegenerative disorders are only symptomatic in nature and do not change the course of the disease. Gene therapy plays an important role in disease modifying therapeutic strategies. Herein, we have designed and optimized a series of highly branched poly(β-amino ester)s (HPAEs) containing biodegradable disulfide units in the HPAE backbone (HPAESS) and guanidine moieties (HPAESG) at the extremities. The optimized polymers are used to deliver minicircle DNA to multipotent adipose derived stem cells (ADSCs) and astrocytes, and high transfection efficiency is achieved (77% in human ADSCs and 52% in primary astrocytes) whilst preserving over 90% cell viability. Furthermore, the top-performing candidate mediates high levels of nerve growth factor (NGF) secretion from astrocytes, causing neurite outgrowth from a model neuron cell line. This synergistic gene delivery system provides a viable method for highly efficient non-viral transfection of ADSCs and astrocytes