An inexpensive, facile, and environmentally benign method has been developed for the preparation of multiresponsive, dynamic, and self-healing chitosan-based hydrogels. A dibenzaldehyde-terminated telechelic poly(ethylene glycol) (PEG) was synthesized and was allowed to form Schiff base linkages between the aldehyde groups and the amino groups in chitosan. Upon mixing the telechelic PEG with chitosan at 20 °C, hydrogels with solid content of 4-8% by mass were generated rapidly in <60 s. Because of the dynamic equilibrium between the Schiff base linkage and the aldehyde and amine reactants, the hydrogels were found to be self-healable and sensitive to many biochemical-stimuli, such as pH, amino acids, and vitamin B6 derivatives. In addition, chitosan could be digested by enzymes such as papain, leading to the decomposition of the hydrogels. Encapsulation and controlled release of small molecules such as rhodamine B and proteins such as lysozyme have been successfully carried out, demonstrating the potential biomedical applications of these chitosan-based dynamic hydrogels.

Plant hormones play central roles in plant growth, developmental processes, and plant response to biotic and abiotic stresses. On the one hand, plant hormones may allocate limited resources to the most serious stresses; on the other hand, the crosstalks among multiple plant hormone signaling regulate the balance between plant growth and defense. Many studies have reported the mechanism of crosstalks between jasmonic acid (JA) and other plant hormones in plant growth and stress responses. Based on these studies, this paper mainly reviews the crosstalks between JA and other plant hormone signaling in regulating the balance between plant growth and defense response. The suppressor proteins JASMONATE ZIM DOMAIN PROTEIN (JAZ) and MYC2 as the key components in the crosstalks are also highlighted in the review. We conclude that JA interacts with other hormone signaling pathways [such as auxin, ethylene (ET), abscisic acid (ABA), salicylic acid (SA), brassinosteroids (BRs), and gibberellin (GA)] to regulate plant growth, abiotic stress tolerance, and defense resistance against hemibiotrophic pathogens such as Magnaporthe oryzae and Pseudomonas syringae. Notably, JA may act as a core signal in the phytohormone signaling network.

A straightforward method to prepare a novel magnetic self-healing hydrogel has been successfully developed.

An inexpensive, biocompatible self-healing hydrogel as a new injectable cell therapy carrier has been facilely developed.Injectable hydrogels could accommodate irregular shaped defects and remain at the desired position by implanting into tissues through a minimally invasive strategy. 1-3 Some stimuli-responsive injectable hydrogels have been successfully developed. Typically, the hydrogel precursors are injected as liquid and the sol-gel processes are triggered in situ by changing physical/chemical conditions, such as by varying temperature, pH, ionic strength or by redox-initiated, photoinitiated polymerizations, chemical/enzyme catalytic cross-linking reactions and so on. 4-10 The in situ formed hydrogel could remain at a desired position for controlled-release of encapsulated therapeutics. 11 Thus, injectable hydrogels have attracted much research attention for their potential applications for cell therapy and drug delivery. 12,13 However, these traditional injectable hydrogels are generated through drastic change of environmental conditions or using some toxic organic reagents, which will more or less detrimentally affect the encapsulated drugs or cells. 14 Meanwhile, the slow gelation might result in the cargo loss and diffusion from the targeting site while the extremely rapid gelation process might lead to the undesired premature polymerization and delivery failure. 15,16 Synthetic materials that are capable of autonomous healing upon damage have been developed rapidly because of their many potential applications. 17 As a new type of biomaterial, self-healing hydrogels have been considered as an alternative to traditional injectable hydrogels. 18,19 Compared with traditional injectable hydrogels, selfhealing hydrogels could homogeneously encapsulate pharmaceutical drugs/cells ex vivo under physiology conditions, resulting in better repeatable experimental results and higher therapeutic activities of drugs and cells. 20 After injection, the broken hydrogel fragments could regenerate an integral gel at the target site, avoiding the risk of catheter clogging by premature polymerization. Although many new types of self-healing hydrogels have been successfully developed, the major self-healing hydrogels for biomedical applications are based on the self-assembly of amphiphilic peptides, 18,21 which are normally expensive and complicated to prepare since those peptides need to be artificially designed and synthesized using an automated solid phase peptide synthesizer, 22 hindering the large-scale manufacture and counteracting the advantages of those self-healing hydrogels. Thus, preparing a biocompatible self-healing hydrogel using inexpensive gelators through a facile method is critical for the practical application of self-healing hydrogels.Recently, we developed a facile approach to prepare a self-healing hydrogel using cheap chitosan and easily synthesized biocompatible telechelic difunctional poly(ethylene glycol) (DF-PEG) as main components. 23,24 DF-PEG was prepared by esterification of hydroxyl terminate...

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