Table 2. PEG-RGD hydrogel formulations and elastic modulus measurements.
In the Table is reported the comparison of stiffness of PEG-RGD Hydrogel formulations achieved with the synthesis procedure used in the present work (column 4) and as reported in literature[35] (column 5), with the highest RGD molar concentration (3mM). The latter is achieved by pre-reacting the RGD containing peptide with NB functionalities and then by UV-crosslinking. In our procedure all peptides (the one containing RGD and the crosslinking peptide) are reacted simultaneously, allowing a more homogeneous distribution of RGD containing peptide among 8ArmPEG macromers (i.e. avoiding possible “saturation” of the NB terminated arms) and therefore achieving a more efficient crosslinking degree.
| PEG-RGD Hydrogel | Molar ratio 1Cys/NB | 2NB-8ArmPEG wt% | 3Elastic modulus PEG-RGD | 3*Elastic modulus PEG-RGD |
|---|---|---|---|---|
| PEG-RGD1 | 0.4/1 | 4.7 | 0.30 ± 0.13 | 0.02 ± 0.08 |
| PEG-RGD2 | 0.5/1 | 5.0 | 0.87 ± 0.13 | 0.11 ± 0.01 |
| PEG-RGD3 | 0.6/1 | 5.2 | 1.17 ± 0.31 | 0.20 ± 0.03 |
| PEG-RGD4 | 0.7/1 | 5.5 | 2.63 ± 0.38 | 0.71 ± 0.08 |
| PEG-RGD5 | 0.8/1 | 9 | 7.71 ± 0.38 | 1.62 ± 0.03 |
| PEG-RGD6 | 0.8/1 | 12.5 | 13.7 ± 0.48 | 4.47 ± 0.65 |
Cys=Cysteine terminal group of the crosslinking peptide. RGD concentration is fixed to 3mM
NB-8ArmPEG wt% is the weight% of macromer used to synthesize PEG-RGD hydrogels.
Stiffness measurements by micropipette aspiration.[40]