Journal of Colloid and Interface Science 2007 316 367 75, Dec 15, 2007
pH-responsive microgels are crosslinked polymer particles that swell when the pH approaches the p... more pH-responsive microgels are crosslinked polymer particles that swell when the pH approaches the pK a of the ionic monomer incorporated within the particles. In recent work from our group it was demonstrated that the mechanical properties of degenerated intervertebral discs (IVDs) could be restored to normal values by injection of poly(EA/MAA/BDDA) (ethylacrylate, methacrylic acid and butanediol diacrylate) microgel dispersions [J.M. Saunders, T. Tong, C.L. Le Maitre, T.J. Freemont, B.R. Saunders, Soft Matter 3 (2007) 486]. In this work we report the pH dependent swelling and rheological properties of poly(MMA/MAA/EGDMA) (methylmethacrylate and ethyleneglycol dimethacrylate) microgel dispersions. This system was investigated because it contains monomers that are already used as biomaterials. The poly(MMA/MAA/EGDMA) particles exhibit pH-triggered volume swelling ratios of up to ca. 250. The swelling onset for these particles occurs at pH values greater than ca. 6.0. A pK a for these particles of ca. 6.7 is consistent with titration and swelling data. Fluid-to-gel phase diagrams for concentrated poly(MMA/MAA/EGDMA) dispersions were determined as a function of polymer volume fraction and pH using tube-inversion measurements. The rheological properties for the gelled microgel dispersions were investigated using dynamic rheology measurements. The elastic modulus data for the poly(MMA/MAA/EGDMA) gelled dispersions were compared to data for poly(EA/MAA/BDDA) microgels. A similar pH-dependence for the elastic modulus was apparent. The maximum elastic modulus was achieved at a pH of about 7.0. The elastic modulus is an exponentially increasing function of polymer volume fraction at pH 7.0. Preliminary cell challenge experimental data are reported that indicate that gelled poly(MMA/MAA/EGDMA) microgel dispersions are biocompatible with cells from human intervertebral discs. However, the duration over which these experiments could be performed was limited by gradual redispersion of the gelled microgel dispersions. Based on the results presented it is suggested that poly(MMA/MAA/EGDMA) microgel would be a good candidate as a biomaterial for structural support of soft connective tissues. (B.R. Saunders). degenerated intervertebral discs (IVDs) could be restored by injection of poly(EA/MAA/BDDA) microgel dispersion followed by pH triggered swelling. (EA, MAA and BDDA are ethylacrylate, methacrylic acid and butanediol diacrylate, respectively.) Poly(EA/MAA/BDDA) microgel was originally developed by Rodriguez et al. [5] In this study we replaced EA and BDDA with components which should be more acceptable for potential use in the body. The comonomers chosen were MMA and EGDMA, which are methylmethacrylate and ethyleneglycol dimethacrylate, respectively. The aims of this study were to investigate the pH-dependent swelling behaviour of two poly(MMA/MAA/EGDMA) microgels and compare the data with those for poly(EA/MAA/BDDA) microgel to determine
... Sarah Lallya, Ruixue Liua, Chonlakan Supasuteekula, Brian R. Saunders*a and Tony Freemontb. a... more ... Sarah Lallya, Ruixue Liua, Chonlakan Supasuteekula, Brian R. Saunders*a and Tony Freemontb. a Biomaterials Research Group, The ... Firstly, it is possible that the low molecular weight crosslinking monomers simply hold the MG particles together by increased van der Waals ...
pH-responsive microgels are crosslinked polymer particles that swell when the pH approaches the p... more pH-responsive microgels are crosslinked polymer particles that swell when the pH approaches the pK a of the ionic monomer incorporated within the particles. In recent work from our group it was demonstrated that the mechanical properties of degenerated intervertebral discs (IVDs) could be restored to normal values by injection of poly(EA/MAA/BDDA) (ethylacrylate, methacrylic acid and butanediol diacrylate) microgel dispersions [J.M. Saunders, T. Tong, C.L. Le Maitre, T.J. Freemont, B.R. Saunders, Soft Matter 3 (2007) 486]. In this work we report the pH dependent swelling and rheological properties of poly(MMA/MAA/EGDMA) (methylmethacrylate and ethyleneglycol dimethacrylate) microgel dispersions. This system was investigated because it contains monomers that are already used as biomaterials. The poly(MMA/MAA/EGDMA) particles exhibit pH-triggered volume swelling ratios of up to ca. 250. The swelling onset for these particles occurs at pH values greater than ca. 6.0. A pK a for these particles of ca. 6.7 is consistent with titration and swelling data. Fluid-to-gel phase diagrams for concentrated poly(MMA/MAA/EGDMA) dispersions were determined as a function of polymer volume fraction and pH using tube-inversion measurements. The rheological properties for the gelled microgel dispersions were investigated using dynamic rheology measurements. The elastic modulus data for the poly(MMA/MAA/EGDMA) gelled dispersions were compared to data for poly(EA/MAA/BDDA) microgels. A similar pH-dependence for the elastic modulus was apparent. The maximum elastic modulus was achieved at a pH of about 7.0. The elastic modulus is an exponentially increasing function of polymer volume fraction at pH 7.0. Preliminary cell challenge experimental data are reported that indicate that gelled poly(MMA/MAA/EGDMA) microgel dispersions are biocompatible with cells from human intervertebral discs. However, the duration over which these experiments could be performed was limited by gradual redispersion of the gelled microgel dispersions. Based on the results presented it is suggested that poly(MMA/MAA/EGDMA) microgel would be a good candidate as a biomaterial for structural support of soft connective tissues. (B.R. Saunders). degenerated intervertebral discs (IVDs) could be restored by injection of poly(EA/MAA/BDDA) microgel dispersion followed by pH triggered swelling. (EA, MAA and BDDA are ethylacrylate, methacrylic acid and butanediol diacrylate, respectively.) Poly(EA/MAA/BDDA) microgel was originally developed by Rodriguez et al. [5] In this study we replaced EA and BDDA with components which should be more acceptable for potential use in the body. The comonomers chosen were MMA and EGDMA, which are methylmethacrylate and ethyleneglycol dimethacrylate, respectively. The aims of this study were to investigate the pH-dependent swelling behaviour of two poly(MMA/MAA/EGDMA) microgels and compare the data with those for poly(EA/MAA/BDDA) microgel to determine
pH-responsive microgels are cross-linked polymer colloids that swell when the pH approaches the p... more pH-responsive microgels are cross-linked polymer colloids that swell when the pH approaches the pK a of the particles. In this work, we present a comprehensive investigation of pH-triggered particle swelling and gel formation for a range of microgels containing methacrylic acid (MAA). The microgels investigated have the general composition poly(A/MAA/X), where A and X are the primary co-monomer and cross-linking monomer, respectively. The primary co-monomers were methyl methacrylate (MMA), ethyl acrylate (EA) or butyl methacrylate. The cross-linking monomers were either butanediol diacrylate (BDDA) or ethyleneglycol dimethacrylate (EGDMA). The microgels were studied using scanning electron microscopy, photon correlation spectroscopy (PCS) and dynamic rheology measurements. Gel phase diagrams were also constructed. The particles swelled significantly at pH values greater than approximately 6.0. It was shown that poly(EA/ MAA/X) microgels swelled more strongly than poly (MMA/MAA/X) microgels. Furthermore, greater swelling occurred for particles prepared using EGDMA than BDDA. Concentrated dispersions of all the microgels studied exhibited pH-triggered gel formation. It was found that the fluid-to-gel transitions for the majority of the six microgel dispersions investigated could be explained using PCS data. In those cases, gelation was attributed to a colloidal glass transition. Interestingly, the microgels that were considered to have the highest hydrophobic content gelation occurred under conditions where little particle swelling was evident from PCS. The data presented show that gelled poly(EA/MAA/BDDA) and poly(MMA/MAA/ EGDMA) microgel dispersions have the strongest elasticities at pH=7.
pH-responsive microgels are crosslinked polymer colloids that swell when the pH approaches the pK... more pH-responsive microgels are crosslinked polymer colloids that swell when the pH approaches the pK a of the particles. They have potential application for injectable gels for tissue repair and drug delivery systems. This study focuses on the pH-triggered gelation behaviour of a series of poly (EA/MAA/X) microgels. EA and MAA are ethylacrylate and methacrylic acid. Here, we investigate the effect
Journal of Colloid and Interface Science 2007 316 367 75, Dec 15, 2007
pH-responsive microgels are crosslinked polymer particles that swell when the pH approaches the p... more pH-responsive microgels are crosslinked polymer particles that swell when the pH approaches the pK a of the ionic monomer incorporated within the particles. In recent work from our group it was demonstrated that the mechanical properties of degenerated intervertebral discs (IVDs) could be restored to normal values by injection of poly(EA/MAA/BDDA) (ethylacrylate, methacrylic acid and butanediol diacrylate) microgel dispersions [J.M. Saunders, T. Tong, C.L. Le Maitre, T.J. Freemont, B.R. Saunders, Soft Matter 3 (2007) 486]. In this work we report the pH dependent swelling and rheological properties of poly(MMA/MAA/EGDMA) (methylmethacrylate and ethyleneglycol dimethacrylate) microgel dispersions. This system was investigated because it contains monomers that are already used as biomaterials. The poly(MMA/MAA/EGDMA) particles exhibit pH-triggered volume swelling ratios of up to ca. 250. The swelling onset for these particles occurs at pH values greater than ca. 6.0. A pK a for these particles of ca. 6.7 is consistent with titration and swelling data. Fluid-to-gel phase diagrams for concentrated poly(MMA/MAA/EGDMA) dispersions were determined as a function of polymer volume fraction and pH using tube-inversion measurements. The rheological properties for the gelled microgel dispersions were investigated using dynamic rheology measurements. The elastic modulus data for the poly(MMA/MAA/EGDMA) gelled dispersions were compared to data for poly(EA/MAA/BDDA) microgels. A similar pH-dependence for the elastic modulus was apparent. The maximum elastic modulus was achieved at a pH of about 7.0. The elastic modulus is an exponentially increasing function of polymer volume fraction at pH 7.0. Preliminary cell challenge experimental data are reported that indicate that gelled poly(MMA/MAA/EGDMA) microgel dispersions are biocompatible with cells from human intervertebral discs. However, the duration over which these experiments could be performed was limited by gradual redispersion of the gelled microgel dispersions. Based on the results presented it is suggested that poly(MMA/MAA/EGDMA) microgel would be a good candidate as a biomaterial for structural support of soft connective tissues. (B.R. Saunders). degenerated intervertebral discs (IVDs) could be restored by injection of poly(EA/MAA/BDDA) microgel dispersion followed by pH triggered swelling. (EA, MAA and BDDA are ethylacrylate, methacrylic acid and butanediol diacrylate, respectively.) Poly(EA/MAA/BDDA) microgel was originally developed by Rodriguez et al. [5] In this study we replaced EA and BDDA with components which should be more acceptable for potential use in the body. The comonomers chosen were MMA and EGDMA, which are methylmethacrylate and ethyleneglycol dimethacrylate, respectively. The aims of this study were to investigate the pH-dependent swelling behaviour of two poly(MMA/MAA/EGDMA) microgels and compare the data with those for poly(EA/MAA/BDDA) microgel to determine
... Sarah Lallya, Ruixue Liua, Chonlakan Supasuteekula, Brian R. Saunders*a and Tony Freemontb. a... more ... Sarah Lallya, Ruixue Liua, Chonlakan Supasuteekula, Brian R. Saunders*a and Tony Freemontb. a Biomaterials Research Group, The ... Firstly, it is possible that the low molecular weight crosslinking monomers simply hold the MG particles together by increased van der Waals ...
pH-responsive microgels are crosslinked polymer particles that swell when the pH approaches the p... more pH-responsive microgels are crosslinked polymer particles that swell when the pH approaches the pK a of the ionic monomer incorporated within the particles. In recent work from our group it was demonstrated that the mechanical properties of degenerated intervertebral discs (IVDs) could be restored to normal values by injection of poly(EA/MAA/BDDA) (ethylacrylate, methacrylic acid and butanediol diacrylate) microgel dispersions [J.M. Saunders, T. Tong, C.L. Le Maitre, T.J. Freemont, B.R. Saunders, Soft Matter 3 (2007) 486]. In this work we report the pH dependent swelling and rheological properties of poly(MMA/MAA/EGDMA) (methylmethacrylate and ethyleneglycol dimethacrylate) microgel dispersions. This system was investigated because it contains monomers that are already used as biomaterials. The poly(MMA/MAA/EGDMA) particles exhibit pH-triggered volume swelling ratios of up to ca. 250. The swelling onset for these particles occurs at pH values greater than ca. 6.0. A pK a for these particles of ca. 6.7 is consistent with titration and swelling data. Fluid-to-gel phase diagrams for concentrated poly(MMA/MAA/EGDMA) dispersions were determined as a function of polymer volume fraction and pH using tube-inversion measurements. The rheological properties for the gelled microgel dispersions were investigated using dynamic rheology measurements. The elastic modulus data for the poly(MMA/MAA/EGDMA) gelled dispersions were compared to data for poly(EA/MAA/BDDA) microgels. A similar pH-dependence for the elastic modulus was apparent. The maximum elastic modulus was achieved at a pH of about 7.0. The elastic modulus is an exponentially increasing function of polymer volume fraction at pH 7.0. Preliminary cell challenge experimental data are reported that indicate that gelled poly(MMA/MAA/EGDMA) microgel dispersions are biocompatible with cells from human intervertebral discs. However, the duration over which these experiments could be performed was limited by gradual redispersion of the gelled microgel dispersions. Based on the results presented it is suggested that poly(MMA/MAA/EGDMA) microgel would be a good candidate as a biomaterial for structural support of soft connective tissues. (B.R. Saunders). degenerated intervertebral discs (IVDs) could be restored by injection of poly(EA/MAA/BDDA) microgel dispersion followed by pH triggered swelling. (EA, MAA and BDDA are ethylacrylate, methacrylic acid and butanediol diacrylate, respectively.) Poly(EA/MAA/BDDA) microgel was originally developed by Rodriguez et al. [5] In this study we replaced EA and BDDA with components which should be more acceptable for potential use in the body. The comonomers chosen were MMA and EGDMA, which are methylmethacrylate and ethyleneglycol dimethacrylate, respectively. The aims of this study were to investigate the pH-dependent swelling behaviour of two poly(MMA/MAA/EGDMA) microgels and compare the data with those for poly(EA/MAA/BDDA) microgel to determine
pH-responsive microgels are cross-linked polymer colloids that swell when the pH approaches the p... more pH-responsive microgels are cross-linked polymer colloids that swell when the pH approaches the pK a of the particles. In this work, we present a comprehensive investigation of pH-triggered particle swelling and gel formation for a range of microgels containing methacrylic acid (MAA). The microgels investigated have the general composition poly(A/MAA/X), where A and X are the primary co-monomer and cross-linking monomer, respectively. The primary co-monomers were methyl methacrylate (MMA), ethyl acrylate (EA) or butyl methacrylate. The cross-linking monomers were either butanediol diacrylate (BDDA) or ethyleneglycol dimethacrylate (EGDMA). The microgels were studied using scanning electron microscopy, photon correlation spectroscopy (PCS) and dynamic rheology measurements. Gel phase diagrams were also constructed. The particles swelled significantly at pH values greater than approximately 6.0. It was shown that poly(EA/ MAA/X) microgels swelled more strongly than poly (MMA/MAA/X) microgels. Furthermore, greater swelling occurred for particles prepared using EGDMA than BDDA. Concentrated dispersions of all the microgels studied exhibited pH-triggered gel formation. It was found that the fluid-to-gel transitions for the majority of the six microgel dispersions investigated could be explained using PCS data. In those cases, gelation was attributed to a colloidal glass transition. Interestingly, the microgels that were considered to have the highest hydrophobic content gelation occurred under conditions where little particle swelling was evident from PCS. The data presented show that gelled poly(EA/MAA/BDDA) and poly(MMA/MAA/ EGDMA) microgel dispersions have the strongest elasticities at pH=7.
pH-responsive microgels are crosslinked polymer colloids that swell when the pH approaches the pK... more pH-responsive microgels are crosslinked polymer colloids that swell when the pH approaches the pK a of the particles. They have potential application for injectable gels for tissue repair and drug delivery systems. This study focuses on the pH-triggered gelation behaviour of a series of poly (EA/MAA/X) microgels. EA and MAA are ethylacrylate and methacrylic acid. Here, we investigate the effect
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