Spatially engineering tri-layer nanofiber dressings featuring asymmetric wettability for wound healing

Inspired by the skin structure,an asymmetric wettability tri-layer nanofiber membrane(TNM)consisting of hydrophilic inner layer loaded with lidocaine hydrochloride(LID),hydrophobic middle layer with ciprofloxacin(CIP)and hydrophobic outer layer has been created.The hydrophobic outer layer endows the TNM with waterproof function and anti-adhesion from contaminants.The hydrophobic middle layer with CIP preserves long-term inhibition of bacteria growth and the hydrophilic inner layer with LID possesses optimal waterabsorbing capacity and air permeability.The TNM dramatically elevates the water contact angles from 10°(inner layer)to 120(outer layer),indicating an asymmetric wettability,which could directionally transport wound exudate within the materials and meanwhile maintain a comfortable and moist environment to promote wound healing.Furthermore,the sequential release of LID and CIP could relieve pain rapidly and achieve antibacterial effect in the long run,respectively.In addition,the TNM shows superior biocompatibility towards L929 cells.The in vivo results show the TNM could prevent infection,accelerate epithelial regeneration and significantly accelerate wound healing.This study indicates the developed TNM with asymmetrical wettability and synergetic drug release shows great potential as a wound dressing in clinical application.

Research advances of nanomaterials for the acceleration of fracture healing

The bone fracture cases have been increasing yearly,accompanied by the increased number of patients experiencing non-union or delayed union after their bone fracture.Although clinical materials facilitate fracture healing(e.g.,metallic and composite materials),they cannot fulfill the requirements due to the slow degradation rate,limited osteogenic activity,inadequate osseointegration ability,and suboptimal mechanical properties.Since early 2000,nanomaterials successfully mimic the nanoscale features of bones and offer unique properties,receiving extensive attention.This paper reviews the achievements of nanomaterials in treating bone fracture(e.g.,the intrinsic properties of nanomaterials,nanomaterials for bone defect filling,and nanoscale drug delivery systems in treating fracture delayed union).Furthermore,we discuss the perspectives on the challenges and future directions of developing nanomaterials to accelerate fracture healing.

Tannic acid and silicate-functionalized polyvinyl alcohol-hyaluronic acid hydrogel for infected diabetic wound healing

Healing of chronic diabetic wounds is challenging due to complications of severe inflammatory microenvironment,bacterial infection and poor vascular formation.Herein,a novel injectable polyvinyl alcohol-hyaluronic acid-based composite hydrogel was developed,with tannic acid(TA)and silicate functionalization to fabricate an‘all-in-one’hydrogel PTKH.On one hand,after being locally injected into the wound site,the hydrogel underwent a gradual sol-gel transition in situ,forming an adhesive and protective dressing for the wound.Manipulations of rheological characteristics,mechanical properties and swelling ability of PTKH could be performed via regulating TA and silicate content in hydrogel.On the other hand,PTKH was capable of eliminating reactive oxygen species overexpression,combating infection and generating a cell-favored microenvironment for wound healing acceleration in vitro.Subsequent animal studies demonstrated that PTKH could greatly stimulate angiogenesis and epithelization,accompanied with inflammation and infection risk reduction.Therefore,in consideration of its impressive in vitro and in vivo outcomes,this‘all-in-one’multifunctional hydrogel may hold promise for chronic diabetic wound treatment.

An On-Chip Viscoelasticity Sensor for Biological Fluids

There are so many non-Newtonian fluids in our daily life,such as milk,blood,cytoplasm,and mucus,most of which are viscoelastic heterogeneous liquid containing cells,inorganic ion,metabolites,and hormones.In microfluidic microparticle-manipulating applications,the target particles are practically distributed within the biological fluids like blood and urine.The viscoelasticity of biological fluid is constantly ignored for simplicity especially when the fluid is substantially diluted and contains rather complex components.However,even the fluid’s ultraweak viscoelasticity actually affects the microparticle migration and may bring a completely different behavior compared with the Newtonian fluids.As a result,a robust and easy operated on-chip viscoelasticity sensor is potential and desired in many research and industrial fields,including assay sample preparation,clinical diagnostics,and on-chip sensor.In this work,we employed stable non-Newtonian fluid-polyethylene oxide(PEO)solutions with various concentrations to investigate and calibrate effects of the weak fluidic viscoelasticity on microparticle behaviors in a double-layered microfluidic channel.An analogy-based database of fluidic patterns for viscoelasticity sensing and relaxation time measurement was established.Then,we tested different biological fluids including blood plasma and fetal bovine serum and proved that they exhibited similar viscoelasticity effects to the PEO solutions with the corresponding concentration,which reached a good agreement with available results by references.The detection limitation of relaxation time can reach 1 ms.It promised a robust and integrated on-chip microfluidic viscoelasticity sensor for different biological fluids without complicated calculations.