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Characterization of complexation of poly (N-isopropylacrylamide-co-2-(dimethylamino) ethyl methacrylate) thermoresponsive cationic nanogels with salmon sperm DNA.

Moselhy J, Vira T, Liu FF, Wu XY - Int J Nanomedicine (2009)

Bottom Line: Quaternized P[NIPAM/DMAEMAQ] TCNGs did not undergo sharp VPT up to 50 degrees C.The VPT of P[NIPAM/DMAEMAQ]/sasDNA diminished in magnitude with increasing W(p)/W(d) suggesting greater compaction of the polyplexes.The findings demonstrate that stable TCNGs can be prepared with controllable responsive properties determined by the nature of the cationic charge incorporated and may have potential as vehicles for DNA delivery.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada M5S 3M2.

ABSTRACT
Thermoresponsive cationic nanogel (TCNG) networks based on N-isopropylacrylamide (NIPAM), 2-(dimethylamino)ethyl methacrylate (DMAEMA), and quaternary alkyl ammonium halide salts of DMAEMA (DMAEMAQ) were synthesized by dispersion polymerization technique. The thermoresponsive properties of TCNGs and TCNG-salmon sperm DNA (sasDNA) polyplexes were characterized in aqueous media of various pH and ionic strength. P[NIPAM] and P[NIPAM/DMAEMA] TCNGs exhibited sharp volume phase transition (VPT) in water at critical temperatures (T(c)) of 32 degrees C and 36 degrees C, respectively. Quaternized P[NIPAM/DMAEMAQ] TCNGs did not undergo sharp VPT up to 50 degrees C. The VPT of uncomplexed TCNGs were sensitive to the ionic composition and ionic strength of salts in solution, but were insensitive to pH in the range 5.0 to 7.4. The VPT of P[NIPAM/DMAEMAQ]/sasDNA diminished in magnitude with increasing W(p)/W(d) suggesting greater compaction of the polyplexes. The distinct phase-transition properties of P[NIPAM/DMAEMA]/sasDNA and P[NIPAM/DMAEMAQ]/sasDNA polyplexes were attributed to the condensing capability of polycations and to differences in the spatial distribution of structural charges in quaternized and nonquaternized networks. The findings demonstrate that stable TCNGs can be prepared with controllable responsive properties determined by the nature of the cationic charge incorporated and may have potential as vehicles for DNA delivery.

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Related in: MedlinePlus

Temperature dependence of zeta-potential of NDQPI6 and NDQPI6/sasDNA in DDIW.
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f9-ijn-4-153: Temperature dependence of zeta-potential of NDQPI6 and NDQPI6/sasDNA in DDIW.

Mentions: To further probe the nature of complexation of sasDNA with P[NIPAM/DMAEMAQ] TCNGs, the temperature dependence of surface charge was investigated. As seen in Figure 9, NDQPI6 exhibited a decrease in the value of ζ from + 12.3 mV to + 5.0 mV through the VPT, with a noticeable decrease near Tc ∼36 °C. However, a decrease in particle volume through the VPT would be expected to increase the charge density on the surface of TCNGs and, therefore, increase ζ̃. Noting the relatively small change in the diameter (Figure 3) and decrease in ζ of NDQPI6 with temperature, it appears as though collapse of the polymer chains results in screening of the point charges derived from the quaternized amine functional groups on the gel. NDQPI6/sasDNA polyplexes exhibit highly negative surface charge values (−9.0 mV to −19.8 mV) that decreases with increasing temperature up to 45 °C. At Wp/Wd = 5, NDQPI6/sasDNA were slightly more negatively charged than NDQPI6, suggesting that some or all of the additional sasDNA was bound to the surface of the TCNG in the complex. The increase in negative charge of NDQPI6/sasDNA with temperature is likely caused by the 3.5-fold change in hydrodynamic volume of the polyplex through the temperature range. Therefore, it appears that the stabilizing effect of sasDNA is the result of its binding at the surface of the polyplex and that the stabilizing effects are further enhanced as a result of contraction of the gel network during VPT.


Characterization of complexation of poly (N-isopropylacrylamide-co-2-(dimethylamino) ethyl methacrylate) thermoresponsive cationic nanogels with salmon sperm DNA.

Moselhy J, Vira T, Liu FF, Wu XY - Int J Nanomedicine (2009)

Temperature dependence of zeta-potential of NDQPI6 and NDQPI6/sasDNA in DDIW.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2747350&req=5

f9-ijn-4-153: Temperature dependence of zeta-potential of NDQPI6 and NDQPI6/sasDNA in DDIW.
Mentions: To further probe the nature of complexation of sasDNA with P[NIPAM/DMAEMAQ] TCNGs, the temperature dependence of surface charge was investigated. As seen in Figure 9, NDQPI6 exhibited a decrease in the value of ζ from + 12.3 mV to + 5.0 mV through the VPT, with a noticeable decrease near Tc ∼36 °C. However, a decrease in particle volume through the VPT would be expected to increase the charge density on the surface of TCNGs and, therefore, increase ζ̃. Noting the relatively small change in the diameter (Figure 3) and decrease in ζ of NDQPI6 with temperature, it appears as though collapse of the polymer chains results in screening of the point charges derived from the quaternized amine functional groups on the gel. NDQPI6/sasDNA polyplexes exhibit highly negative surface charge values (−9.0 mV to −19.8 mV) that decreases with increasing temperature up to 45 °C. At Wp/Wd = 5, NDQPI6/sasDNA were slightly more negatively charged than NDQPI6, suggesting that some or all of the additional sasDNA was bound to the surface of the TCNG in the complex. The increase in negative charge of NDQPI6/sasDNA with temperature is likely caused by the 3.5-fold change in hydrodynamic volume of the polyplex through the temperature range. Therefore, it appears that the stabilizing effect of sasDNA is the result of its binding at the surface of the polyplex and that the stabilizing effects are further enhanced as a result of contraction of the gel network during VPT.

Bottom Line: Quaternized P[NIPAM/DMAEMAQ] TCNGs did not undergo sharp VPT up to 50 degrees C.The VPT of P[NIPAM/DMAEMAQ]/sasDNA diminished in magnitude with increasing W(p)/W(d) suggesting greater compaction of the polyplexes.The findings demonstrate that stable TCNGs can be prepared with controllable responsive properties determined by the nature of the cationic charge incorporated and may have potential as vehicles for DNA delivery.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada M5S 3M2.

ABSTRACT
Thermoresponsive cationic nanogel (TCNG) networks based on N-isopropylacrylamide (NIPAM), 2-(dimethylamino)ethyl methacrylate (DMAEMA), and quaternary alkyl ammonium halide salts of DMAEMA (DMAEMAQ) were synthesized by dispersion polymerization technique. The thermoresponsive properties of TCNGs and TCNG-salmon sperm DNA (sasDNA) polyplexes were characterized in aqueous media of various pH and ionic strength. P[NIPAM] and P[NIPAM/DMAEMA] TCNGs exhibited sharp volume phase transition (VPT) in water at critical temperatures (T(c)) of 32 degrees C and 36 degrees C, respectively. Quaternized P[NIPAM/DMAEMAQ] TCNGs did not undergo sharp VPT up to 50 degrees C. The VPT of uncomplexed TCNGs were sensitive to the ionic composition and ionic strength of salts in solution, but were insensitive to pH in the range 5.0 to 7.4. The VPT of P[NIPAM/DMAEMAQ]/sasDNA diminished in magnitude with increasing W(p)/W(d) suggesting greater compaction of the polyplexes. The distinct phase-transition properties of P[NIPAM/DMAEMA]/sasDNA and P[NIPAM/DMAEMAQ]/sasDNA polyplexes were attributed to the condensing capability of polycations and to differences in the spatial distribution of structural charges in quaternized and nonquaternized networks. The findings demonstrate that stable TCNGs can be prepared with controllable responsive properties determined by the nature of the cationic charge incorporated and may have potential as vehicles for DNA delivery.

Show MeSH
Related in: MedlinePlus