The Solution Conformation of Polymer Brushes Determines their Interactions with DNA and Transfection Efficiency

Transcription

1 The Solution Conformation of Polymer Brushes Determines their Interactions with DNA and Transfection Efficiency 0 Mahentha Krishnamoorthy #,, Danyang Li #,, Amir S. Sharili, Tina Gulin-Sarfraz, Jessica M. Rosenholm and Julien E. Gautrot*, Institute of Bioengineering and School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London, E NS, UK. Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, Newark Street, London, E AT, UK. Pharmaceutical Sciences Laboratory, Faculty of Science and Engineering, Abo Akademi University, 00 Turku, Finland. # Both authors contributed equally to this work. *To whom correspondence should be addressed, j.gautrot@qmul.ac.uk. Supplementary Information

2 Figure S. Evolution of the thickness of PDMAEMA brushes (dry) as a function of the polymerisation time, determined by ellipsometry. 0 Figure S. Decomposition of nanoparticles quantified by thermogravimetric analysis. Samples characterised: bare silica nanoparticles (Bare SiO, grey line), silica nanoparticles after initiator functionalisation (SiO -initiator, turquoise line) and brushes grafted from silica nanoparticles after min (SiO -PDMAEMA-, blue line), 0 min (SiO -PDMAEMA-0, red line), 0 min (SiO -PDMAEMA-0, green line) and 0 min (SiO -PDMAEMA-0, magenta line). The heating rate was 0 o C/min and decomposition was in air.

3 Swollen brush thickness / nm Figure S. Comparison of the thickness of polymer brushes grown from silicon wafers and silica nanoparticles at different time points. Thicknesses of brushes grown from silicon wafers (blue circles) were determined via ellipsometry. Thicknesses of brushes grown from silica nanoparticles (red circles) were determined from TGA data (weight loss quantification from Figure S, after correction for initiator grafting; thicknesses determined from Equation S). Differences between this data set and the data set in Figure S (growth from silicon wafers) are due to the use of a different batch of catalyst for polymer brush growth presented in Figure S nm 0 nm ph Figure S. Swelling of PDMAEMA brushes quantified by in situ ellipsometry, as a function of ph. The ionic strength of the medium was kept constant using solutions of NaCl 0 mm. Red line and data points, 0 nm dry PDMAEMA brushes. Blue line and data points, 0 nm dry PDMAEMA brushes.

4 Figure S. Transfection efficiency of SiO -g-pdmaema nanoparticles with HaCaT cells, measured via the expression of EGFP (epifluorescence images) h after transfection.

5 00 00 Bound DNA / ng/cm Time / s Figure S. DNA binding to PDMAEMA brushes investigated by SPR. Typical SPR traces recorded during the exposure of PDMAEMA brushes (0 nm) to DNA solutions ( g/ml). The ph of all buffers (0 mm NaCl, blue line; PBS, green line; HBS, red line) was adjusted to.. 00 HBS ph HBS ph HBS Immobilised DNA / ng/cm DNA ph ph Time / s Figure S. DNA binding and desorption to and from PDMAEMA brushes investigated by SPR. Typical SPR traces recorded during the exposure of PDMAEMA brushes (0 nm) to DNA solutions ( g/ml). The ph of the 0 mm NaCl solution used as buffer was adjusted to. Following DNA adsorption and equilibration, a solution of 0 mm NaCl at a different ph (ph, red line and ph, blue line) was injected to investigate the desorption of DNA from PDMAEMA brushes at the corresponding ph.

6 Figure S. GPC measurement of PDMAEMA chains cleaved from silica nanoparticle.

7 Equation S: δ = W PDMAEMAρ SiO R + R W SiO ρ R PDMAEMA where W PDMEAMA is the weight loss percentage (TGA) corresponding to the decomposition of the PDMAEMA component, W SiO is the residual weight percentage, ρ SiO is the density of bulk SiO (. g/cm ), ρ PDMAEMA is the density of DMAEMA (. g/cm ), R ( nm) is the average radius of bare silica nanoparticle, is the dry PDMAEMA thickness on silica nanoparticle. Equation S: σ = W PDMAEMA W ρv SiO N A SiO M PDMAEMA S SiO 0 is the grafting density, W PDMEAMA (0 %) is the weight loss percentage (TGA) corresponding to the decomposition of the organic component, W SiO ( %) is the residual weight percentage, ρ is the density of bulk SiO (. g/cm ), V SiO is the volume of SiO nanoparticle calculated from the average diameter of SiO particles (0 nm), NA is Avogadro s number, MPDMAEMA is the molecular weight of the PDMAEMA, and S SiO is the surface area of SiO nanoparticle calculated from the average diameter of SiO particles (0 nm). () Chen, J.; Liu, M.; Chen, C.; Gong, H.; Gao, C. ACS Appl Mater Interfaces 0,,.