Drug release kinetics of poly(glycerol sebacate urethane) scaffolds for soft tissue engineering
Date Issued
May 2022
Author(s)
Abstract
In this study, three different poly(glycerol sebacate urethane), (PGSU) scaffolds
were fabricated with an anisotropic microstructure and characterized their drug release
kinetics (DRK). PGSU scaffolds with different ratios of hexamethyl diisocyanate (HDI)
and polymer poly(glycerol sebacate urethane), pre-(PGS) concentration, were
fabricated and investigated for their aforementioned physical properties. PGSU was
synthesized with pre-PGS at concentrations 10% and 15% w/v% and HDI was added
at molar concentrations (glycerol:HDI) 1:0.8 and 1:1.0. Freeze-drying with custom
made moulds and ice templating, were used to form an anisotropic PGSU scaffold. The
nomenclature of the samples is PGSU X-Y% where X refers to HDI ratio (0.8 or 1.0)
and Y to polymer concentration (w/v%) (10% or 15%). The aim of this study was to
study the DRK therefore the PGSU scaffolds were characterized for their
microstructure, hydrophilicity (water contact angle and swelling rate), their drug loading
efficiency, degradation rate and finally the DRK. PGSU scaffolds were characterized
for their microstructure SEM and were found to exhibit an anisotropic open pore
microstructure. The hydrophilicity was tested using contact angle and swelling ratio and
were found to exhibit a fairly hydrophilic surface with a linear swelling rate. DRK were
studied by loading BSA in scaffolds, using an in-house derived dynamic loading method
which used vacuum/ventilation cycles. It resulted to a 75% drug loading efficiency,
which is considered very good especially for non-hydrophilic materials. Then bovine
serum albumin (BSA) was released by soaking the scaffold in phosphate buffer solution
(PBS) solution on a rocker at 100 rpm for 28 days. The samples collected at different
time points were analyzed using bicinchoninic acid (BCA), to determine the amount of
protein released over time. A linear release rate was found and almost all samples
withheld and released the protein over a period of at least 19 days. Finally, the
degradation rate was studied by soaking the PGSU scaffolds in lipase enzyme and
enzyme free PBS solution for 42 days in a shaker incubator, at 37oC and 100 rpm. The
mass of the scaffolds was taken at multiple time points and compared with the initial
mass to derive the degradation rate, the degradation rate was considered to be too
slow. These results demonstrate that the glycerol:HDI molar ratio and polymer concentration affect the properties of the scaffold, the DRK technique developed by our
group was successful and the fabricated PGSU scaffolds can be used in soft TE.
were fabricated with an anisotropic microstructure and characterized their drug release
kinetics (DRK). PGSU scaffolds with different ratios of hexamethyl diisocyanate (HDI)
and polymer poly(glycerol sebacate urethane), pre-(PGS) concentration, were
fabricated and investigated for their aforementioned physical properties. PGSU was
synthesized with pre-PGS at concentrations 10% and 15% w/v% and HDI was added
at molar concentrations (glycerol:HDI) 1:0.8 and 1:1.0. Freeze-drying with custom
made moulds and ice templating, were used to form an anisotropic PGSU scaffold. The
nomenclature of the samples is PGSU X-Y% where X refers to HDI ratio (0.8 or 1.0)
and Y to polymer concentration (w/v%) (10% or 15%). The aim of this study was to
study the DRK therefore the PGSU scaffolds were characterized for their
microstructure, hydrophilicity (water contact angle and swelling rate), their drug loading
efficiency, degradation rate and finally the DRK. PGSU scaffolds were characterized
for their microstructure SEM and were found to exhibit an anisotropic open pore
microstructure. The hydrophilicity was tested using contact angle and swelling ratio and
were found to exhibit a fairly hydrophilic surface with a linear swelling rate. DRK were
studied by loading BSA in scaffolds, using an in-house derived dynamic loading method
which used vacuum/ventilation cycles. It resulted to a 75% drug loading efficiency,
which is considered very good especially for non-hydrophilic materials. Then bovine
serum albumin (BSA) was released by soaking the scaffold in phosphate buffer solution
(PBS) solution on a rocker at 100 rpm for 28 days. The samples collected at different
time points were analyzed using bicinchoninic acid (BCA), to determine the amount of
protein released over time. A linear release rate was found and almost all samples
withheld and released the protein over a period of at least 19 days. Finally, the
degradation rate was studied by soaking the PGSU scaffolds in lipase enzyme and
enzyme free PBS solution for 42 days in a shaker incubator, at 37oC and 100 rpm. The
mass of the scaffolds was taken at multiple time points and compared with the initial
mass to derive the degradation rate, the degradation rate was considered to be too
slow. These results demonstrate that the glycerol:HDI molar ratio and polymer concentration affect the properties of the scaffold, the DRK technique developed by our
group was successful and the fabricated PGSU scaffolds can be used in soft TE.
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