Thermal-Recoverable Tough Hydrogels Enhanced by Porphyrin Decorated Graphene Oxide.

Wang Wang,Su Su,Qiu Qiu,Wei Wei,Pantoya Pantoya,Hasan Hasan,Hu Hu,Vargas Vargas

doi:10.3390/nano9101487

Abstract

Artificial tissue materials usually suffer properties and structure loss over time. As a usual strategy, a new substitution is required to replace the worn one to maintain the functions. Although several approaches have been developed to restore the mechanical properties of hydrogels, they require direct heating or touching, which cannot be processed within the body. In this manuscript, a photothermal method was developed to restore the mechanical properties of the tough hydrogels by using near infrared (NIR) laser irradiation. By adding the porphyrin decorated graphene oxide (PGO) as the nanoreinforcer and photothermal agent into carrageenan/polyacrylamide double network hydrogels (PDN), the compressive strength of the PDN was greatly improved by 104%. Under a short time of NIR laser irradiation, the PGO effectively converts light energy to thermal energy to heat the PDN hydrogels. The damaged carrageenan network was rebuilt, and a 90% compressive strength recovery was achieved. The PGO not only significantly improves the mechanical performance of PDN, but also restores the compressive property of PDN via a photothermal method. These tough hydrogels with superior photothermal recovery may work as promising substitutes for load-bearing tissues.

Highlights

Hydrogels are three-dimensional networks composed of a high-molecular-weight polymer, water, and cross-linker, which have been employed as scaffolds in tissue engineering [1,2,3], carriers for drug delivery [4,5], and super-absorbents in disposable products [6,7]
The 0.1 mg/mL porphyrin decorated graphene oxide (PGO) solution showed a higher temperature increase (∆T = 41.6 ◦C) than the 0.1 mg/mL graphene oxide (GO) solution (∆T = 21.7 ◦C), which suggests that 91.7% more heat was converted from near infrared (NIR) irradiation (808 nm, 2.5 W cm2, 10 min) by PGO compared to the GO solution
These results demonstrate that PGO can efficiently adsorb NIR light and transfer it into heat energy

Summary

Introduction

Hydrogels are three-dimensional networks composed of a high-molecular-weight polymer, water, and cross-linker, which have been employed as scaffolds in tissue engineering [1,2,3], carriers for drug delivery [4,5], and super-absorbents in disposable products [6,7]. Double network hydrogels, which use sacrificial bonds to achieve high strength, possess inferior fatigue resistance under continuous mechanical loading-unloading cycles [13] This drawback severely limits the development of DN hydrogels as potential substitutes for load-bearing tissues, like cartilage. In our previous study [40], biocompatible porphyrin immobilized graphene oxide (PGO) has been successfully developed, which can achieve high photothermal conversion under 808 nm laser irradiation In this manuscript, biocompatible porphyrin decorated graphene oxide (PGO) is first introduced into the double network hydrogels to enhance the mechanical properties and possess NIR photothermal recovery. The sacrificial network, double helix structures in carrageenan, is reformed, and approximately 90% compressive strength of the PGO reinforced carrageenan/polyacrylamide double network (PDN) hydrogels is recovered These PDN gels exhibit improved mechanical properties and superior photothermal recovery compared to the previous double network hydrogels, which may find potential applications as promising substitutes for load-bearing tissues

Materials

Materials Characterization

Compressive Measurement

Results and Discussions

Thermal Recovery