| 摘要: | Background
Tissue healings such as chronic wounds, bone defects, tendon-bone interfaces are great challenges to health care professionals due to various hidden factors including pathogens, neurovascular diseases, inflammatory cascade, low cell proliferation and cell migration. Recently, graphene and graphene-family have emerged as a shining star in biomaterials for tissue engineering and drug carrier applications due to their excellent properties, which could overcome the limitations of current hydrogel – based strategies and fulfill tissue healing requirements. In addition, the incorporation of graphene oxide (GO) nanosheets into gelatin - based hydrogels to obtain a synergic effect has recently attracted intensive attention for various biomedical applications. Depending on the requirements of the safety, the gel strength and reversibility, crosslinked gelatin – GO hydrogels can be achieved via physical (nonthermal plasma) or chemical (genipin) approaches.
Aims
To evaluate the effects of nonthermal atmospheric pressure argon plasma (NT - APP) on the synthesis of crosslinked gelatin - GO nanocomposite hydrogel for application as a drug delivery system.
To develop a feasible method to impregnate GO into genipin - crosslinked gelatin and control the GO particles released from nanocomposite hydrogel for application as antibacterial wound dressings.
Materials and Methods
Firstly, mechanical stirring synthesis of gelatin-GO hydrogel (GGO) was treated by NT - APP for 10 minutes. Hydrogel products after plasma treatment were examined physicochemical, mechanical properties, morphology, and biocompatibility by FTIR, Rheology, Scan Electron Microscope (SEM), and cell viability assays. Later, different concentrations of alendronate (ALN) - loading plasma treated hydrogels were investigated for drug releasing behaviors in accordance with material degradation profile. ALN is the most common bisphosphonates used for treatment of osteoporosis, some cancers, and metabolic bone diseases.
Secondly, GGO pre-hydrogel was crosslinked by different genipin (Gp) concentrations. The obtained nanocomposite hydrogels were characterized by FTIR, Rheology, SEM, and water absorption capacity. The in vitro studies of biocompatibility, antibacterial, wound healing, GO release kinetics in accordance with the degradation rate of nanocomposite hydrogels were thoroughly investigated to estimate the potential application as chronic wound dressings.
Results
The argon plasma induced the crosslinking of GO and gelatin matrices via covalent and non-covalent bonds to create a thin film nanocomposite hydrogel (PT) on surface exposed to the glow discharge. The PT exhibited an excellent gel strength with storage modulus of 341 kPa, gel-to-sol transition phase at 65 ºC, high hydrophilicity, and prolonged degradation time up to three weeks. Notably, ALN was grafted on PT gels via functional groups such as amide on ALN and carboxyl on PT, leading to sustained cumulative release of ALN at least 21 days. Furthermore, cytotoxicity assays showed that PT demonstrated high biocompatibility supporting L929 cells viability and proliferation.
On the other hand, genipin crosslinked gelatin – GO hydrogels showed that the GO reinforced hydrogels were significantly enhanced the gel strength without chemical modification caused by GO. Moreover, GO incorporated hydrogels controlled the GO release kinetics depending on the crosslinking degrees and enzymatic levels following degradation rates. In addition, the nanocomposite hydrogels demonstrated good biocompatibility towards HMSC-ad 7510 and CG1475 cell lines. Most importantly, the released GO particles displayed uniformity and dispersity, retained the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa via their sharp edges and wrapping mechanisms, and promoted human fibroblasts migration.
Conclusions
These findings suggest that nonthermal plasma is a novel method for fabrication of stable gelatin - GO nanocomposite hydrogel, provides a material with excellent gel biomechanics for controlled release of ALN. The sustainable release of ALN may suit for various utilizations such as tendon - bone healing and bone substitutes. Lastly, taking advantage of the versatility of multifunctional GO sheets, we highly believe that the incorporation of GO into genipin crosslinked gelatin hydrogels will be a feasible strategy to develop a multifunctional wound dressing for the requirements of chronic wound healing. |
