Fabrication of Polypyrrole-Grafted Gelatin-Based Hydrogel with Conductive, Self-Healing, and Injectable Properties

Abstract

The self-healing hydrogel and conductive hydrogel have attracted extensive attention in tissue engineering. The selfhealing hydrogel can restore its original structure and functionality after damage. The conductive hydrogel is beneficial to the differentiation and proliferation of electrical-stimuli-responsive cells. It is significant to integrate the self-healing ability and the electrical conductivity into a single hydrogel system. Herein we present polypyrrole-grafted gelatin-based hydrogels with combined conductive, self-healing and injectable properties. Methacrylic anhydride was first grafted onto gelatin to form double-bond-functionalized gelatin. Then, the commonly used conductive polymer polypyrrole was grafted onto gelatin by reacting with the double bond. Finally, the polypyrrole-grafted gelatin was mixed with ferric ions to construct the hydrogels. As revealed by the results, the hydrogels possess good conductivity owing to the incorporated polypyrrole and ferric ions. The reversible ionic interactions of ferric ions with gelatin and polypyrrole endow the hydrogels with selfhealing abilities. It is interesting that the hydrogels exhibit good injectable properties attributed to their self-healing abilities. Moreover, the hydrogels show a controllable porous structure, an inhibited swelling ability, and good cytocompatibility and blood compatibility.

Electrically Conductive and 3D‐Printable Oxidized Alginate‐Gelatin Polypyrrole:PSS Hydrogels for Tissue Engineering

“…In a recent approach without using ALG, gelatin‐methacrylate (GelMA)‐PPy hydrogels have been engineered, [ 97 ] which allowed cell attachment and cytocompatibility with respect to C2C12 myoblasts. [ 97 ] The hydrogel showed similar conductivities (≈0.8–1.6 S m −1 ) as the ADA‐GEL‐PPy:PSS hydrogels here, but in comparison resulted in softer hydrogels upon mechanical compression. One reason for the higher stiffness of ADA‐GEL‐PPy:PSS may be the higher overall hydrogel concentration of GEL and ADA used in our study.…”

“…The higher amount of PPy in the system as well as the combination of ionic-and enzymatic-crosslinking in the ADA-GEL hydrogel may result in the stiffer hydrogels observed. [55,85] In summary, our hydrogels combine the celladhesion properties provided by gelatin [97] with 3D-printability, doping, [57,72] and degradation properties of ADA, [98] which are requirements to fabricate advanced tissue engineering constructs. The results suggest the suitability of the PPy-modified ADA-GEL scaffolds in soft-to-hard tissue ranges of ≈1-1.5 MPa, which is closer in the range of native cartilage tissue [99,100] than pristine ADA-GEL.…”

Advocating Electrically Conductive Scaffolds with Low Immunogenicity for Biomedical Applications: A Review

“…Synthetic polymers, such as polylactic acid (PLA), polyglycolide acid (PGA), and polyhydroxyalkanoates (PHA) can also act as the base material of scaffolds. Figure 3 and Table 1 list the common techniques that are used to fabricate conductive scaffolds [ 17 , 24 , 28 , 29 , 30 , 31 , 32 ]. Additionally, Figure 4 shows that distinct scaffold fabrication techniques yield distinct forms and structures of scaffolds, including interconnected porous, hydrogel, and nanofibrous mat [ 18 , 25 , 29 , 30 , 33 ].…”

“… Techniques in fabricating scaffolds and their respective scanning electron microscope images [ 18 , 29 , 30 , 31 , 39 , 40 ]. …”

Advance of Electroconductive Hydrogels for Biomedical Applications in Orthopedics

“…Conductive polymers need to combine with ideal supporting materials to cover up their instability and susceptibility to oxidation. Lately, Wang et al [22] prepared polypyrrole-grafted gelatin-based hydrogels with conductivity, self-healing, and injectability. ey first grafted methacrylate anhydride (MA) onto the gelatin to form a double bond functional gelatin (GelMA) through a physical cross-linking network.…”