The use of isothermal titration calorimetry and molecular dynamics to show variability in DNA transfection performance.
The mechanism causing variability in DNA transfection efficacy for low-molecular-weight pDMAEMA (poly(2-(dimethylamino)ethyl methacrylate) and pDMAEMA-b-pHEMA (poly(2-(dimethyl amino)ethylmethacrylate)-block-poly(2-hydroxyl methacrylate)) has so far remained unclear, apart from the evidence of beneficial effects of the pHEMA grafting. This study has explicitly characterized the electrostatically driven self-assembly process of linear polymethacrylate polymers with DNA-generating nanocarriers for efficient gene transfection. Isothermal titration calorimetry (ITC) showed clear differences in binding-heat profiles of homo-polycationic and pHEMA grafted polymers with DNA. Polyethylene imine, a branched polycationic polymer of 25kDa with high transfection potential that has previously been successfully used in transfection experiments, demonstrated a heat flow profile that was partly identical to pDMAEMA-b-pHEMA. Computational molecular dynamics (MD) simulated the folding process of polymer in water from a linear to a coiled state: homo-pDMAEMA and pHEMA grafts reduced their overall positive charge accessibility upon folding, down to 45% and 63%, respectively. The homo-pDMAEMA formed the globular conformation more preferably than pHEMA grafts, thus impeding electrostatic interaction with DNA. These findings substantiate the known disadvantage of low-molecular-weight linear polymers compared to higher-molecular-weight polymers in transfection performance; here we have disclosed the ability of a non-cationic chain elongation to be beneficial for the self-assembly process. The combination of MD and ITC has proved to be a suitable approach for carrier-payload interaction studies and may be used to predict the efficacy of a polymer as a nanocarrier from the flexibility of its structure.
Department of Pharmaceutics and Biopharmacy, Philipps-Universität, Ketzerbach 63, D-35032 Marburg, Germany. olga.samsonova@staff.uni-marburg.de
Olga
O
Samsonova
Serghei
S
Glinca
Adam
A
Biela
Christian
C
Pfeiffer
Eyas
E
Dayyoub
Damla
D
Sahin
Gerhard
G
Klebe
Thomas
T
Kissel
D000818:Animals; D002151:Calorimetry / Q000379:methods*; D004247:DNA / Q000378:metabolism*; D008297:Male; D008689:Methacrylates / Q000737:chemistry; D018625:Microscopy, Atomic Force; D056004:Molecular Dynamics Simulation; D009757:Nylons / Q000737:chemistry; D010316:Particle Size; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry; D055672:Static Electricity; D013816:Thermodynamics; D014162:Transfection / Q000592:standards*; D014867:Water / Q000737:chemistry
D008689:Methacrylates; D009757:Nylons; C407037:poly(2-(dimethylamino)ethyl methacrylate); D014867:Water; D011102:Polyhydroxyethyl Methacrylate; D004247:DNA