Thermo-Responsive Nanocomposite Hydrogels Based on PEG-b-PLGA Diblock Copolymer and Laponite

Abstract

Poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) (PEG-b-PLGA) diblock copolymers are widely known as polymeric surfactants for biomedical applications, and exhibit high solubility in water compared to PLGA-b-PEG-b-PLGA triblock copolymers known as gelation agents. In order to overcome the difficulties in the preparation of thermo-responsive hydrogels based on PLGA-b-PEG-b-PLGA due to the low solubility in water, the fabrication of thermo-responsive hydrogels based on PEG-b-PLGA with high solubility in water was attempted by adding laponite to the PEG-b-PLGA solution. In detail, PEG-b-PLGA with high solubility in water (i.e., high PEG/PLGA ratio) were synthesized. Then, the nanocomposite solution based on PEG-b-PLGA and laponite (laponite/PEG-b-PLGA nanocomposite) was fabricated by mixing the PEG-b-PLGA solutions and the laponite suspensions. By using the test tube inversion method and dynamic mechanical analysis (DMA), it was found that thermo-responsive hydrogels could be obtained by using PEG-b-PLGA, generally known as polymeric surfactants, and that the gelation temperature was around the physiological temperature and could be regulated by changing the solution composition. Furthermore, from the structural analysis by small angle neutron scattering (SANS), PEG-b-PLGA was confirmed to be on the surface of the laponite platelets, and the thermosensitive PEG-b-PLGA on the laponite surface could trigger the thermo-responsive connection of the preformed laponite network.

Maleimide-functionalised PLGA-PEG nanoparticles as mucoadhesive carriers for intravesical drug delivery

“…Our results corroborate with SANS studies of PLGA-PEG based block copolymers published previously [47,[54][55][56][57] keeping in mind the difference in composition, molecular weights and methods of preparation. For example, PEO-PLGA-PEO [55] and PLGA-PEG-PLGA [56] triblock copolymers were investigated using SANS.…”

“…The combination of core-shell spherical model in combination with Debay form factor was used for the fitting the scattering profile from laponite free nanoparticles made of PEG-PLGA copolymers. The radius of a core and the micelles was found 1.6 and 4.7 nm, respectively, giving the shell thickness value to be of 3.1 nm [57]. We note here that the model used in our work is very close to the one reported in [57].…”

“…Interesting contrast variation SANS study was performed for laponite/PEG1.0k-PLGA0.8k and laponite/PEG1.0k-PLGA1.6k nanocomposites in a broad range of D2O/H2O mixture concentrations [57].…”

Copolymer/Clay Nanocomposites for Biomedical Applications

“…There have been other smart/stimuli‐responsive nanocomposite hydrogels based on various copolymer/clay combinations such as oligo(ethylene glycol)/laponite, [ 131 ] 2‐(2‐methoxyethoxy) ethyl methacrylate/fibrillar attapulgite, [ 132 ] laponite incorporated keratin/pluronic/chitosan blends, [ 152 ] poly (2‐methoxyethylacrylate‐ co ‐ N , N ‐dimethylacrylamide)/laponite, [ 118a,154 ] poly(ethylene glycol)‐ b ‐poly( d , l ‐lactide‐ co ‐glycolide)/laponite, [ 142 ] poly(2‐methoxyethyl acrylate)‐ co ‐( N , N ‐dimethylacrylamide)/laponite, [ 154 ] and poly (acrylamide‐ co ‐sodium acrylate)/laponite. [ 77 ] The responsive behavior of the copolymer/clay nanocomposite hydrogels is due to many factors such as phase transition temperature (LCST and UCST), inter/intra molecular hydrogen bond interaction, type of crosslinking, density and protonation–deprotonation of side/pendant groups of the polymer chains.…”

Structures and Applications of Thermoresponsive Hydrogels and Nanocomposite-Hydrogels Based on Copolymers with Poly (Ethylene Glycol) and Poly (Lactide-Co-Glycolide) Blocks

“…They further revealed that transplantation of mouse myoblast C2C12 cells using thermoresponsive nanocomposite hydrogels dramatically enhanced tissue regeneration and functional recovery in model mice with skeletal muscle injury, whereas no recovery was observed for transplantation using PLGA-PEG-PLGA hydrogels. In 2019, Maeda et al reported on thermoresponsive nanocomposite hydrogel composed of laponite and PEG-PLGA diblock copolymers (Figure 7f) [69]. We synthesized PEG-PLGA with a high PEG-PLGA ratio of 1.27 and prepared the nanocomposite solution by mixing laponite aqueous suspension and PEG-PLGA aqueous solution.…”