Conducting polymer hydrogels (CPHs) emerge as excellent functional materials, as they harness the advantages of conducting polymers with the mechanical properties and continuous 3D nanostructures of hydrogels. This bicomponent organization results in soft, all-organic, conducting micro-/nanostructures with multifarious material applications. However, the application of CPHs as functional materials for biomedical applications is currently limited due to the necessity to combine the features of biocompatibility, self-healing, and fine-tuning of the mechanical properties. To overcome this issue, we choose to combine a protected dipeptide as the supramolecular gelator, owing to its intrinsic biocompatibility and excellent gelation ability, with the conductive polymer polyaniline (PAni), which was polymerized in situ. Thus, a two-component, all-organic, conducting hydrogel was formed. Spectroscopic evidence reveals the formation of the emeraldine salt form of PAni by intrinsic doping. The composite hydrogel is mechanically rigid with a very high storage modulus (G′) value of ~2 MPa, and the rigidity was tuned by changing the peptide concentration. The hydrogel exhibits ohmic conductivity, pressure sensitivity, and, importantly, self-healing features. By virtue of its self-healing property, the polymeric nonmetallic hydrogel can reinstate its intrinsic conductivity when two of its macroscopically separated blocks are rejoined. High cell viability of cardiomyocytes grown on the composite hydrogel demonstrates its noncytotoxicity. These combined attributes of the hydrogel allowed its utilization for dynamic range pressure sensing and as a conductive interface for electrogenic cardiac cells. The composite hydrogel supports cardiomyocyte organization into a spontaneously contracting system. The composite hydrogel thus has considerable potential for various applications.

Despite incremental improvements in the field of tissue engineering, no technology is currently available for producing completely autologous implants where both the cells and the scaffolding material are generated from the patient, and thus do not provoke an immune response that may lead to implant rejection. Here, a new approach is introduced to efficiently engineer any tissue type, which its differentiation cues are known, from one small tissue biopsy. Pieces of omental tissues are extracted from patients and, while the cells are reprogrammed to become induced pluripotent stem cells, the extracellular matrix is processed into an immunologically matching, thermoresponsive hydrogel. Efficient cell differentiation within a large 3D hydrogel is reported, and, as a proof of concept, the generation of functional cardiac, cortical, spinal cord, and adipogenic tissue implants is demonstrated. This versatile bioengineering approach may assist to regenerate any tissue and organ with a minimal risk for immune rejection.

Self‐assembled peptide hydrogels represent the realization of peptide nanotechnology into biomedical products. There is a continuous quest to identify the simplest building blocks and optimize their critical gelation concentration (CGC). Herein, a minimalistic, de novo dipeptide, Fmoc‐Lys(Fmoc)‐Asp, as an hydrogelator with the lowest CGC ever reported, almost fourfold lower as compared to that of a large hexadecapeptide previously described, is reported. The dipeptide self‐assembles through an unusual and unprecedented two‐step process as elucidated by solid‐state NMR and molecular dynamics simulation. The hydrogel is cytocompatible and supports 2D/3D cell growth. Conductive composite gels composed of Fmoc‐Lys(Fmoc)‐Asp and a conductive polymer exhibit excellent DNA binding. Fmoc‐Lys(Fmoc)‐Asp exhibits the lowest CGC and highest mechanical properties when compared to a library of dipeptide analogues, thus validating the uniqueness of the molecular design which confers useful properties for various potential applications.

Cardiac tissue engineering aims to create cardiac tissue constructs that recapitulate the structure and function of the native heart. This approach has been widely used for creating myocardial implants for regenerative medicine, and more recently, for developing in vitro cardiotoxicity screening assays. However, once the engineered myocardial tissues are implanted or subjected to pharmacological stimuli, their performance should be monitored. Currently, there is no biomaterial that promotes functional tissues assembly while providing real‐time information about their function, in situ. In this study, the piezoelectric phenomenon is sought to be exploited, to measure the contractions generated by engineered cardiac tissues. A poly‐(vinylidene fluoride) (PVDF)‐based electrospun fiber scaffold is developed, and it is hypothesized that the contractions of cardiomyocytes in the scaffold will induce mechanical deformations, which will result in measurable electric voltage. The PVDF scaffolds are characterized and optimized for supporting formation of aligned, functional, cardiac tissues. The scaffolds' function is then validated as sensors for tissue contraction and it is demonstrated that they can sense contractions of tissues constructed from as few as 5 × 105 cardiomyocytes. Furthermore, it is demonstrated that human induced pluripotent stem cells can be directly seeded and differentiated to cardiomyocytes, and then mature over the course of 40 days on the PVDF fiber scaffolds.

Engineering of extracellular matrix (ECM) mimics, with most of the necessary features of a natural ECM, is a crucial requirement for the design of biomaterials. The natural ECM encompasses a 3D network of intertwined protein nanofibers which contains complex biomolecules for communication between cells.[1] Short peptide-based 3D nanostructured supramolecular hydrogels are excellent candidates for ECM mimicry as they provide networks of fibers which resemble the ECM structure. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Modifications of certain oligopeptide termini with bio-active ligands, aimed to introduce bio-active components into the system, have also been reported. [22][23][24][25] The tripeptide sequence Arg-Gly-Asp (RGD), which was first recognized in fibronectin as an independent cell attachment site, is the most commonly used bio-active ligand. [26] This tri-peptide sequence is recognized by the α v β 3 and α 5 β 1 integrins located in cell membranes, thus facilitating the coupling of the ECM with the cytoskeleton. [27] Owing to these attributes, the RGD ligand has been introduced into supramolecular or polymeric substrates to facilitate cell attachment. [28][29][30][31] Fmoc-RGD [Fmoc = N-(fluorenyl-9-methoxycarbonyl)] is one of the simplest RGD derivatives capable of forming hydrogels with an inter-connected fibrous network. [15,27] Ulijn's group reported Fmoc-RGD based supramolecular hydrogels in neutral aqueous solution by appropriate mixing of two short peptidebased building blocks, Fmoc-FF (F = phenylalanine) and Fmoc-RGD and utilized them as scaffolds for cell culture. [15] They proposed that Fmoc-RGD alone was not able to form β-sheet fibrils, although in the composite gels of Fmoc-FF and Fmoc-RGD (10-30 wt% Fmoc-RGD), signatures of β-sheet structures were found. We later reported flanking of the RGD sequence by aromatic moieties, demonstrating the hydrogelation of RGD derivatives, including Fmoc-FRGD and Fmoc-RGDF. [32] Hamley and co-workers showed that the simple Fmoc-RGD moiety, without any modification or mixing with other hydrogelator peptides, could from nano-fibrous hydrogels. [27] Castelletto and co-workers prepared monoliths of Fmoc-RGD gels at a high peptide concentration of 10 wt% which showed excellent Bio-Inspired Soft MaterialsPeptide-based supramolecular hydrogels are utilized as functional materials in tissue engineering, axonal regeneration, and controlled drug delivery. The Arg-Gly-Asp (RGD) ligand based supramolecular gels have immense potential in this respect, as this tripeptide is known to promote cell adhesion. Although several RGD-based supramolecular hydrogels have been reported, most of them are devoid of adequate resilience and long-range stability for in vitro cell culture. In a quest to improve the mechanical properties of these tripeptide-based gels and their durability in cell culture media, the Fmoc-RGD hydrogelator is non-covalently functionalized with a biocompatible and biodegradable polymer, chitosan, resulting in a composite hydrog...