Advances in the application of hydrogel-based scaffolds for tendon repair

Tendon injuries often lead to joint dysfunction due to the limited self-regeneration capacity of tendons.Repairing tendons is a major challenge for surgeons and imposes a signif-icant financial burden on society.Therefore,there is an urgent need to develop effective stra-tegies for repairing injured tendons.Tendon tissue engineering using hydrogels has emerged as a promising approach that has attracted considerable interest.Hydrogels possess excellent biocompatibility and biodegradability,enabling them to create an extracellular matrix-like growth environment for cells.They can also serve as a carrier for cells or other substances to accelerate tendon repair.In the past decade,numerous studies have made significant prog-ress in the preparation of hydrogel scaffolds for tendon healing.This review aims to provide an overview of recent research on the materials of hydrogel-based scaffolds used for tendon tis-sue engineering and discusses the delivery systems based on them.

Hydrogel-based artificial enzyme for combating bacteria and accelerating wound healing

Artificial enzymes have provided great antimicrobial activity to combat wound infection.However,the lack of tissue repair capability compromised their treatment effect.Therefore,development of novel artificial enzyme concurrently with the excellent antibacterial activity and the property of promoting wound healing are required.Here,we demonstrated the hydrogel-based artificial enzyme composed of copper and amino acids possessed intrinsic peroxidase-like catalytic activity,which could combat wound pathogen effectively and accelerate wound healing by stimulating angiogenesis and collagen deposition.Furthermore,the system possesses good biocompatibility for practical application.The synergic effect of the hydrogel-based artificial enzyme promises the system as a new paradigm in bacteria-infected wound healing therapy.

Bio-inspired hydrogel-based bandage with robust adhesive and antibacterial abilities for skin closure

Although conventional suturing techniques are commonly used in assisting wound closure,they do pose limited conduciveness and may lead to secondary injury to wound tissues.Inspired by marine organism mussels,we designed and manufactured a bio-inspired hydrogel-based bandage with tough wet tissue adhesion to substitute traditional surgical suture,accelerate wound healing and avoid infection.Poly(γ-glutamic acid)was modified with 3,4-dihydroxyphenylalanine and glycidyl methacylate,then introduced into the acrylic acid-co-acrylamide hydrogel matrix with robust mechanical properties.The hydrogel bandage showed strong chemical linkage adhesion(70±2.1 kPa),which is 2.8 times that of commercial tissue adhesive fibrin glue(25±2.2 kPa).The hydrogel bandage can not only maintain the self-stability,but is also capable of self-tuning adhesive strength in the range of 14-70 kPa to achieve different adhesion effects by tuning constituent ratio.The bandage has desirable compression properties(0.7±0.11 MPa)and tensile elongation(about 25 times),which ensures its resistance to damages,especially in joint spaces.Secondly,the bandage was endowed with antioxidant and endogenous broad-spectrum antibacterial properties with its catechol structure.Results also demonstrated excellent cell compatibility and blood compatibility,certifying its eligible biological safety profile.In a rat full-thickness cutaneous deficiency model,we can clearly observe that the bandage possesses the ability to promote wound healing(only need 6 days).Above all,this research provides a new strategy for the emergency treatment of liver hemostasis and myocardial repair during disaster rescue.

Rapid field testing of mercury pollution by designed fluorescent biosensor and its cells-alginate hydrogel-based paper assay

With increasing industrial activities,mercury has been largely discharged into environment and caused serious environmental problems.The growing level of mercury pollution has become a huge threat to human health due to its significant biotoxicity.Therefore,the simple and fast means for on-site monitoring discharged mercury pollution are highly necessary to protect human beings from its pernicious effects in time.Herein,a"turn off"fluorescent biosensor(mCherry L199 C)for sensing Hg2+was successfully designed based on direct modification of the chromophore environment of fluorescent protein mCherry.For rapid screening and characterization,the designed variant of mCherry(mCherry L199 C)was directly expressed on outer-membrane of Escherichia coli cells by cell surface display technique.The fluorescent biosensor was characterized to have favorable response to Hg2+at micromole level among other metal ions and over a broad pH range.Further,the cells of the fluorescent biosensor were encapsulated in alginate hydrogel to develop the cells-alginate hydrogel-based paper.The cells-alginate hydrogel-based paper could detect mercury pollution in 5 min with simple operation process and inexpensive equipment,and it could keep fluorescence and activity stable at 4℃ for 24 hr,which would be a high-throughput screening tool in preliminarily reporting the presence of mercury pollution in natural setting.

The design and investigation of hydrogel-based metamaterials with ultra large negative hygroscopic expansion ratio

A design strategy for a mechanical metamaterial with large negative hygroscopic expansion(NHE)was proposed in this paper.Different from the reported structures,the present metamaterial is designed by constructing repeated lattice microstructure consisting of curved ligaments incorporating hydrogel active layers and polymer support layers and straight polymer bars.When immersed in the solution environment,the swelling of hydrogel layer of such composite structure induces the reversed bending of the ligament,leading to the overall ultra-large shrink(negative expansion)deformation of the metamaterial.Through the new structural design,large NHE effects can be achieved.The theoretical investigation and finite element analysis(FEA)were conducted to demonstrate the large negative expansion effects of such metamaterial.The results showed that the effective NHE ratio of the metamaterial is dependent of the curvature of the curved ligament and the size of both the ligament and the connecting rod.The ultra-large NHE ratios about−80%for the 2D structure and−90%for the 3D version can be obtained by adopting the structural parameters.The newly designed metamaterials have potential applications in medical and other fields.

Hydrogel-based contact lens achieve prolonged,local drug delivery to the eye

With the support by the National Natural Science Foundation of China,the research group led by Prof.Jiang Gangbiao(蒋刚彪)at the Department of Pharmaceutical Engineering,College of Materials and Energy,South China Agricultural University,in collaboration with the research group led by Prof.Yuan

Gelatin-Based Metamaterial Hydrogel Films with High Conformality for Ultra-Soft Tissue Monitoring

Implantable hydrogel-based bioelectronics(IHB)can precisely monitor human health and diagnose diseases.However,achieving biodegradability,biocompatibility,and high conformality with soft tissues poses significant challenges for IHB.Gelatin is the most suitable candidate for IHB since it is a collagen hydrolysate and a substantial part of the extracellular matrix found naturally in most tissues.This study used 3D printing ultrafine fiber networks with metamaterial design to embed into ultra-low elastic modulus hydrogel to create a novel gelatin-based conductive film(GCF)with mechanical programmability.The regulation of GCF nearly covers soft tissue mechanics,an elastic modulus from 20 to 420 kPa,and a Poisson’s ratio from-0.25 to 0.52.The negative Poisson’s ratio promotes conformality with soft tissues to improve the efficiency of biological interfaces.The GCF can monitor heartbeat signals and respiratory rate by determining cardiac deformation due to its high conformability.Notably,the gelatin characteristics of the biodegradable GCF enable the sensor to monitor and support tissue restoration.The GCF metamaterial design offers a unique idea for bioelectronics to develop implantable sensors that integrate monitoring and tissue repair and a customized method for endowing implanted sensors to be highly conformal with soft tissues.

Advanced Biotechnology for Cell Cryopreservation

Cell cryopreservation has evolved as an important technology required for supporting various cell-based applications,such as stem cell therapy,tissue engineering,and assisted reproduction.Recent times have witnessed an increase in the clinical demand of these applications,requiring urgent improvements in cell cryopreservation.However,cryopreservation technology suff ers from the issues of low cryopreservation effi ciency and cryoprotectant(CPA)toxicity.Application of advanced biotechnology tools can signifi cantly improve post-thaw cell survival and reduce or even eliminate the use of organic solvent CPAs,thus promoting the development of cryopreservation.Herein,based on the diff erent cryopreservation mechanisms available,we provide an overview of the applications and achievements of various biotechnology tools used in cell cryopreservation,including trehalose delivery,hydrogel-based cell encapsulation technique,droplet-based cell printing,and nanowarming,and also discuss the associated challenges and perspectives for future development.

The coral-inspired steam evaporator for efficient solar desalination via porous and thermal insulation bionic design

The solar-driven interfacial evaporation(SIE)technology shows great prospects in seawater desalination and sewage treatment,but it is unable to obtain highly efficient and high-quality clean nontoxic water at low cost.Here,a novel biodegradable hydrogel-based solar evaporator(BBH-L)with a bionic coral structure taking Chinese ink as the solar absorber was developed.This evaporator consists of chitosan/polyvinyl alcohol hydrogel and a loofah substrate.The average evaporation rate and efficiency of BBH-L reach 4.37 kg/(m^(2)·h)and 98.2%,respectively,under one sun illumination(1 kW/m^(2)),which are attributed to its excellent thermal localization and water transporting abilities.Meanwhile,high salt resistance enables BBH-L to achieve efficient desalination and purification of other unconventional water.Heavy metal ions in seawater can be effectively removed by chelation and forming hydrogen bonds in hydrogels.This study is anticipated to provide new possibilities to enhance evaporation performance and reduce the costs of water treatment systems.