Thermoresponsive hydrogels in biomedical applications.

Graphene-polymer nanocomposites for structural and functional applications

Hydrogels in a historical perspective: from simple networks to smart materials.

Sonication-induced gelation of silk fibroin for cell encapsulation.

In situ gelling hydrogels for pharmaceutical and biomedical applications.

A biodegradable polymer network hydrogel with both hydrophobic and hydrophilic components was synthesized and characterized. The hydrophobic and hydrophilic components were a three-arm poly(e-caprolactone) maleic acid (PGCL-Ma, as the hydrophobic constituent) and poly(ethylene glycol) diacrylate macromer (PEGDA, as a hydrophilic constituent), respectively. These two polymers were chemically photo-crosslinked to generate a three-dimensional network structure, which were characterized by FT-IR, DSC and SEM. The swelling property of the networks was studied in phosphate-buffered saline (PBS, pH 7.4). The results of this study showed that a wide-range swelling property was obtained by changing the composition ratio of PGCL-Ma to PEGDA. The in vitro release of bovine serum albumin (BSA) from these hydrogels as a function of the PEGDA to PGCL-Ma composition ratio and incubation time was examined and we found that the incorporation of PEGDA into PGCL-Ma increased the initial burst release of BSA. As the PEGDA co...

Synthesis, characterization and drug release from three-arm poly(ε-caprolactone) maleic acid/poly(ethylene glycol) diacrylate hydrogels

The objective of this work was to investigate a new family of hydrophobic-hydrophilic biodegradable hybrid hydrogels as drug carriers. A series of hydrophobic-hydrophilic biodegradable hybrid hydrogels was formulated via photo means from hydrophobic three-arm poly (epsilon-caprolactone) maleic acid (PGCL-Ma) and hydrophilic dextran maleic acid (Dex-Ma) precursors over a wide range of the two precursors' feed ratio (PGCL-Ma/Dex-Ma at 100:0, 70:30, 50:50, 30:70 and 0:100). A low-molecular-weight and hydrophilic drug, the alpha-7 agonist cocaine methiodide, was used as the model drug for the release study from the hybrid hydrogels in pH 7.4 phosphate buffer solution at 37 degrees C. The swelling data of these hybrid hydrogels depended on the hydrophobic to hydrophilic precursors' feed ratio, and there were several-fold differences in swelling ratios between a pure hydrophilic Dex-Ma and a pure hydrophobic PGCL-Ma hydrogels. The presence of the hydrophobic PGCL-Ma component significantly reduced the initial burst swelling of the hybrid hydrogels. Depending on the two precursors' feed ratios, the swelling data during the early period obeyed either Fickian diffusion (for 50:50 PGCL-Ma/Dex-Ma hydrogel), non-Fickian or anomalous transport (for 70:30 and 100:0 PGCL-Ma/Dex-Ma), or relaxation-controlled (for 30:70 and 0:100 PGCL-Ma/Dex-Ma). A wide range of cocaine methiodide release profiles was achieved by controlling hydrophobic to hydrophilic precursors' feed ratios. Initial drug burst release was significantly reduced as the concentration of the hydrophobic PGCL-Ma component increased in the hybrid hydrogels. The bulk of cocaine methiodide released during the 160-h period was via diffusion-controlled mechanism, while degradation-controlled mechanism dominated thereafter.

Biodegradable hydrophobic-hydrophilic hybrid hydrogels: swelling behavior and controlled drug release.

Injectable hydrogel microspheres are prepared by forming an emulsion where hydrogel precursors are in a disperse aqueous phase and polymerizing the hydrogel precursors. In a preferred case, the hydrogel precursors are poly(ethylene glycol) diacrylate and N-isopropylacrylamide and the continuous phase of the emulsion is an aqueous solution of dextran and a dextran solubility reducer. The microspheres will load protein, e.g., cytokines, from aqueous solution.

Injectable hydrogel microspheres from aqueous two-phase system

Sutures elicit an inflammatory response, which may impede the healing process and result in wound complications We recently reported a novel family of biocompatible, biodegradable polymers, amino acid-based poly(ester amide)s (AA-PEA), which we have shown to significantly attenuate the foreign body inflammatory response in vitro Two types of AA-PEA (Phe-PEA and Arg-Phe-PEA) were used to coat silk or plain-gut sutures, which were implanted in the gluteus muscle of C57BL/6 mice, while the uncoated control sutures were implanted in the contralateral side After 3, 7, 14, and 28 days the mean area of inflammation surrounding the sutures was compared Phe-PEA coating of silk sutures significantly decreased inflammation compared with noncoated controls (678 ± 174% after 3d [p = 00014], 516 ± 72% after 7d [p < 0001], and 373 ± 83% after 28d [p = 00001]) when assessed via analysis of photomicrographs using digital image software Phe-PEA coated plain-gut sutures were similarly assessed and demonstrated a significant decrease in the mean area of inflammation across all time points (541 ± 83% after 3 d, 414 ± 39% after 7 d, 715 ± 81% after 14 d, 784 ± 85%, and after 28 d [all p < 00001]) Arg-Phe-PEA coated silk demonstrated significantly less inflammation compared to noncoated controls (613 ± 94% after 3 d, 447 ± 47% after 7 d, 196 ± 8%, and 383 ± 68% after 28 d [all p < 00001]), as did coated plain-gut (374 ± 83% after 3 d [p = 00004], 550 ± 78% after 7 d [p < 00001], 460 ± 46% after 14 d [p < 00001], and 590 ± 79% after 28 d [p < 00001]) Both Phe-PEA and Arg-Phe-PEA coatings significantly decrease the inflammatory response to sutures in vivo for up to 28 days © 2014 Wiley Periodicals, Inc J Biomed Mater Res Part B: Appl Biomater, 103B: 457–463, 2015

Reduction of suture associated inflammation after 28 days using novel biocompatible pseudoprotein poly(ester amide) biomaterials.

The objective of this research is to explore the synthesis of a new family of water soluble polycationic copolymeric precursors that could be photo-crosslinked into hydrogels. The in vitro control release of ovalbumin protein (OVA) from this family of hydrogels was also studied to assess the biomedical potential of this new family polycationic hydrogels. A series of novel poly(VCL-AETA) copolymer hydrogels was fabricated in an aqueous medium via photo-induced polymerization and crosslinking of hydrophobic N-vinylcaprolactam (VCL) and hydrophilic [2-(acryloxy)ethyl]trimethylammonium chloride (AETA) monomers over a wide range of VCL to AETA feed molar ratios of 2:1, 1:1, 1:2, 1:5. N,N'-methylene bisacrylamide (MBA) was used as a crosslinker. Ovalbumin (OVA), a model antigen, was preloaded into poly(VCL-AETA) hydrogel precursors and its release profiles in pH 7.4 PBS at 37 degrees C were investigated as a function of VCL to AETA monomer feed ratios over a period of 4 weeks. The in vitro results showed that OVA initial burst and subsequent sustained releases could be controlled by 3 material parameters: the hydrophobic VCL to hydrophilic AETA monomer feed ratios, crosslinking density and hydrogel degradation rate. Thus, the hydrophobic-hydrophilic VCL-AETA hydrogel network for controlled OVA release could offer advantages over organic solvent-based single component polymer system. However, these in vitro OVA release profiles may change in an in vivo environment.

Da-Qing Wu

Papers

Synthesis, characterization and drug release from three-arm poly(ε-caprolactone) maleic acid/poly(ethylene glycol) diacrylate hydrogels

Biodegradable hydrophobic-hydrophilic hybrid hydrogels: swelling behavior and controlled drug release.

Injectable hydrogel microspheres from aqueous two-phase system

Reduction of suture associated inflammation after 28 days using novel biocompatible pseudoprotein poly(ester amide) biomaterials.

Cationic poly(VCL–AETA) hydrogels and ovalbumin (OVA) release in vitro