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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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Temperature dependence of particle size of NDQPI6 in media of different pH and ionic strength (n = 3).
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f5-ijn-4-153: Temperature dependence of particle size of NDQPI6 in media of different pH and ionic strength (n = 3).

Mentions: Figures 4 and 5 present the effect of ionic strength and pH on the thermal response profiles of P[NIPAM/DMAEMA] and P[NIPAM/DMAEMAQ], respectively. ND9-2 (Figure 4, main frame) is only slightly sensitive to ionic strength showing a tendency to suppress swelling of gels in high ionic strength media, 150 mM PBS. ND9-2 is sensitive to pH as suggested by the more rapid drop in diameter with temperature at pH 7.4 than at pH 5.0. On the other hand, even with the additional charge present on the ND9-2 due to protonation of the tertiary amine groups of DMAEMA, the TCNG aggregated above 36 °C. Apparently, salt concentration has a considerable influence on the stability of P[NIPAM/DMAEMA] TCNGs. By comparison, N100 (Figure 4, inset) and NDQPI6 (Figure 5) exhibit virtually no sensitivity to pH as evidenced by the invariant nature of the thermal transition profiles with pH. This is anticipated, as neither the initiator residues nor the functional monomer possess ionizable groups.


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 particle size of NDQPI6 in media of different pH and ionic strength (n = 3).
© Copyright Policy
Related In: Results  -  Collection

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

f5-ijn-4-153: Temperature dependence of particle size of NDQPI6 in media of different pH and ionic strength (n = 3).
Mentions: Figures 4 and 5 present the effect of ionic strength and pH on the thermal response profiles of P[NIPAM/DMAEMA] and P[NIPAM/DMAEMAQ], respectively. ND9-2 (Figure 4, main frame) is only slightly sensitive to ionic strength showing a tendency to suppress swelling of gels in high ionic strength media, 150 mM PBS. ND9-2 is sensitive to pH as suggested by the more rapid drop in diameter with temperature at pH 7.4 than at pH 5.0. On the other hand, even with the additional charge present on the ND9-2 due to protonation of the tertiary amine groups of DMAEMA, the TCNG aggregated above 36 °C. Apparently, salt concentration has a considerable influence on the stability of P[NIPAM/DMAEMA] TCNGs. By comparison, N100 (Figure 4, inset) and NDQPI6 (Figure 5) exhibit virtually no sensitivity to pH as evidenced by the invariant nature of the thermal transition profiles with pH. This is anticipated, as neither the initiator residues nor the functional monomer possess ionizable groups.

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