Volume 3, Issue 4, Pages 691-705 (October 2017) Dynamic Au-Thiolate Interaction Induced Rapid Self-Healing Nanocomposite Hydrogels with Remarkable Mechanical Behaviors  Haili Qin, Tan Zhang, He-Nan Li, Huai-Ping Cong, Markus Antonietti, Shu-Hong Yu  Chem  Volume 3, Issue 4, Pages 691-705 (October 2017) DOI: 10.1016/j.chempr.2017.07.017 Copyright © 2017 Elsevier Inc. Terms and Conditions

Chem 2017 3, 691-705DOI: (10.1016/j.chempr.2017.07.017) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 1 Schematic Illustrations of Gold-Thiolate Interaction-Triggered Self-Healing Nanocomposite Hydrogels (A) Schematic structure of gold NPs and a list of co-monomers used for polymerization of hydrogels. (B) Schematic formation of GNP hydrogel with modified gold NPs as large crosslinker in the in situ free-radical polymerization. (C) Schematic mechanism for dynamic and reversible RS–Au bonding with NIR laser irradiation (808 nm). Chem 2017 3, 691-705DOI: (10.1016/j.chempr.2017.07.017) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 2 Preparation of GNP Hydrogels (A–C) TEM image of gold NPs functionalized with BACA molecules on the surface (A) and corresponding element mappings of Au (B) and S (C), proving the ultrafine coating of BACA. (D) UV-visible spectra of gold NPs and gold NPs modified with BACA in the form of RS–Au bonds. (E) SEM image of the freeze-dried GNP-15 hydrogel. The uniform pore structures reveal the regular crosslinks in the polymerization. The inset is photograph of the GNP-15 hydrogel. (F–H) Optical images showing the GNP-15 hydrogel with (F) highly stretchable, (G) notch insensitive, and (H) compression-resistant properties. See also Figures S1–S6. Chem 2017 3, 691-705DOI: (10.1016/j.chempr.2017.07.017) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 3 Quantitative Analysis of the Mechanical Performance of GNP Hydrogels (A) Tensile stress-strain curves of GNP hydrogels with different contents of gold NPs and the reference sample, CP-15, with a stretch rate of 100 mm/min. (B) Toughness of CP-15, GNP-5, GNP-10, GNP-15, and GNP-20 hydrogels. Error bars show the SD with sample size of 3. (C) Compression stress-strain curves of GNP hydrogels with different contents of gold NPs. (D) Histograms for tensile strains of notched GNP hydrogels with different contents of gold NPs with notch ratios from 1/3 to 2/3. Error bars show the SD with sample size of 3. (E) Tensile stress-strain curves of GNP hydrogels with 1/3 notch. (F) The K values of hydrogels with different concentrations of gold NPs. See also Figures S7–S11. Chem 2017 3, 691-705DOI: (10.1016/j.chempr.2017.07.017) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 4 High Self-Healing Efficiency of GNP Hydrogels (A) Optical images showing the self-healing procedure between two separated GNP-15 hydrogel pieces under an NIR laser. The healed sample showed a large stretch under an external force. (B) Optical image showing the self-healing process between GNP-15 and GNP-0 hydrogel pieces under an NIR laser. The stretch in the GNP-15 part in the healed sample shows the good healing effect. (C) Optical images showing the self-healing process between GNP-0 hydrogel pieces with the aid of gold NPs under an NIR laser. The healed hydrogel also showed stretchable behavior without rupture. (D) Tensile stress-strain curves of the original GNP-15 hydrogel and the healed sample from two separated GNP-15 hydrogel pieces under an NIR laser. (E) Strains for as-prepared GNP hydrogels with different contents of gold NPs and corresponding healed samples from their pieces under an NIR laser. See also Figures S12–S22 and Table S1. Chem 2017 3, 691-705DOI: (10.1016/j.chempr.2017.07.017) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 5 The Temperature Responsiveness and Potential Biomedical Application of the Hybrid Hydrogel (A) Thermal responsiveness of GNP-15 hydrogel with time when exposed to an NIR laser with various output power. (B–F) Real-time analysis of the opto-thermal performance by the infrared thermal imaging system at 40 s (B), 1 min (C), 2 min (D), 3 min (E), and 4 min (F). (G) Optical image of the hydrogel injected using a syringe with a 20G needle. (H) Cytotoxicity test of the hybrid hydrogel for biocompatibility information. (I) Histogram of drugs released from GNP-15 hydrogel with DOX as the model drug in vitro whether under NIR laser irradiation or not. See also Figure S23. Chem 2017 3, 691-705DOI: (10.1016/j.chempr.2017.07.017) Copyright © 2017 Elsevier Inc. Terms and Conditions