TY - JOUR
T1 - Effect of Temperature and Hydrophilic Ratio on the Structure of Poly(N-vinylcaprolactam)-block-poly(dimethylsiloxane)-block-poly(N-vinylcaprolactam) Polymersomes
T2 - ACS Applied Polymer Materials
AU - Yang, Yiming
AU - Alford, Aaron
AU - Kozlovskaya, Veronika
AU - Zhao, Shidi
AU - Joshi, Himanshu
AU - Kim, Eunjung
AU - Qian, Shuo
AU - Urban, Volker
AU - Cropek, Donald
AU - Aksimentiev, Aleksei
AU - Kharlampieva, Eugenia
N1 - This work was supported US Army Corps of Engineers CERL, W9132T-17-2-0008 and NSF-DMR 1608728 (E.K.), and the National Institute of Health P41-GM104601 (Al.Ak.). UAB High Resolution Imaging Facility (TEM) is also acknowledged. The cryo-EM work was carried out in the UAB Cryo-EM facility (UAB Department of Microbiology). Neutron scattering research conducted at the Bio-SANS instrument, a DOE Office of Science, Office of Biological and Environmental Research resource, used resources at the High Flux Isotope Reactor, a DOE Office of Science, Scientific User Facility operated by the Oak Ridge National Laboratory. The supercomputer time provided through XSEDE Allocation Grant MCA05S028 and the Blue Waters petascale supercomputer system (UIUC) is acknowledged.
PY - 2019/4/12
Y1 - 2019/4/12
N2 - Nanosized polymeric vesicles (polymersomes) assembled from ABA triblock copolymers of poly(N-vinylcaprolactam)-poly(dimethylsiloxane)-poly(N-vinylcaprolactam) (PVCL–PDMS–PVCL) are a promising platform for biomedical applications, as the temperature-responsiveness of the PVCL blocks enables reversible vesicle shrinkage and permeability of the polymersome shell at elevated temperatures. Herein, we explore the effects of molecular weight, polymer block weight ratios, and temperature on the structure of these polymersomes via electron microscopy, dynamic light scattering, small angle neutron scattering (SANS), and all-atom molecular dynamics methods. We show that the shell structure and overall size of the polymersome can be tuned by varying the hydrophilic (PVCL) weight fraction of the polymer: at room temperature, polymers of smaller hydrophilic ratios form larger vesicles that have thinner shells, whereas polymers with higher PVCL content exhibit interchain aggregation of PVCL blocks within the polymersome shell above 50 °C. Model fitting and model-free analysis of the SANS data reveals that increasing the mass ratio of PVCL to the total copolymer weight from 0.3 to 0.56 reduces the temperature-induced change in vesicle diameter by a factor of 3, while simultaneously increasing the change in shell thickness by a factor of 1.5. Finally, by analysis of the shell structures and overall size of polymersomes with various PVCL weight ratios and those without temperature-dependent polymer components, we bring into focus the mechanism of temperature-triggered drug release reported in a previous study. This work provides new fundamental perspectives on temperature-responsive polymersomes and elucidates important structure–property relationships of their constituent polymers.
AB - Nanosized polymeric vesicles (polymersomes) assembled from ABA triblock copolymers of poly(N-vinylcaprolactam)-poly(dimethylsiloxane)-poly(N-vinylcaprolactam) (PVCL–PDMS–PVCL) are a promising platform for biomedical applications, as the temperature-responsiveness of the PVCL blocks enables reversible vesicle shrinkage and permeability of the polymersome shell at elevated temperatures. Herein, we explore the effects of molecular weight, polymer block weight ratios, and temperature on the structure of these polymersomes via electron microscopy, dynamic light scattering, small angle neutron scattering (SANS), and all-atom molecular dynamics methods. We show that the shell structure and overall size of the polymersome can be tuned by varying the hydrophilic (PVCL) weight fraction of the polymer: at room temperature, polymers of smaller hydrophilic ratios form larger vesicles that have thinner shells, whereas polymers with higher PVCL content exhibit interchain aggregation of PVCL blocks within the polymersome shell above 50 °C. Model fitting and model-free analysis of the SANS data reveals that increasing the mass ratio of PVCL to the total copolymer weight from 0.3 to 0.56 reduces the temperature-induced change in vesicle diameter by a factor of 3, while simultaneously increasing the change in shell thickness by a factor of 1.5. Finally, by analysis of the shell structures and overall size of polymersomes with various PVCL weight ratios and those without temperature-dependent polymer components, we bring into focus the mechanism of temperature-triggered drug release reported in a previous study. This work provides new fundamental perspectives on temperature-responsive polymersomes and elucidates important structure–property relationships of their constituent polymers.
KW - SANS
KW - molecular dynamics
KW - poly(N-vinylcaprolactam)
KW - polymersomes
KW - temperature responsive
KW - triblock copolymer
UR - http://www.scopus.com/inward/record.url?scp=85073107380&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85073107380&partnerID=8YFLogxK
U2 - 10.1021/acsapm.8b00259
DO - 10.1021/acsapm.8b00259
M3 - Article
SN - 2637-6105
VL - 1
SP - 722
EP - 736
JO - ACS Applied Polymer Materials
JF - ACS Applied Polymer Materials
IS - 4
ER -