Adhesive and Self-Healing Polyurethanes with Tunable Multifunctionality

Many polyurethanes(PUs)are blood-contacting materials due to their good mechanical properties,fatigue resistance,cytocompatibility,biosafety,and relatively good hemocompatibility.Further functionalization of the PUs using chemical synthetic methods is especially attractive for expanding their applications.Herein,a series of catechol functionalized PU(CPU-PTMEG)elastomers containing variable molecular weight of polytetramethylene ether glycol(PTMEG)soft segment are reported by stepwise polymerization and further introduction of catechol.Tailoring the molecular weight of PTMEG fragment enables a regulable catechol content,mobility of the chain segment,hydrogen bond and microphase separation of the C-PUPTMEG elastomers,thus offering tunability of mechanical strength(such as breaking strength from 1.3 MPa to 5.7 MPa),adhesion,self-healing eficiency(from 14.9%to 96.7%within 2 hours),anticoagulant,antioxidation,anti-inflammatory properties and cellular growth behavior.As cardiovascular stent coatings,the C-PU-PTMEGs demonstrate enough flexibility to withstand deformation during the balloon dilation procedure.Of special importance is that the C-PU-PTMEG-coated surfaces show the ability to rapidly scavenge free radicals to maintain normal growth of endothelial cells,inhibit smooth muscle cell proliferation,mediate inflammatory response,and reduce thrombus formation.With the universality of surface adhesion and tunable multifunctionality,these novel C-PU-PTMEG elastomers should find potential usage in artificial heart valves and surface engineering of stents.

A hydrophobic layer prepared by cyclic grafting of polydimethylsiloxane on magnesium:improved corrosion resistance and biocompatibility

Magnesiumand its alloys have been widely studied as absorbable coronary stent materials.However,the rapid corrosion rate in the intravascular environment inhibits the application of magnesium-based stents.In order to endow magnesium-based stent with appropriate degradation rate and biocompatibility,a hydrophobic layer was constructed by in situ cyclic grafting 4,4'-diphenylmethane diisocyanate and aminopropyl-terminated polydimethylsiloxane on pure magnesium.SEM-EDS,X-ray photoelectron spectroscopy and water contact angle were detected to analyze the chemical composition of the layer.The amino groups were confirmed to be introduced on the surface which provide a platform for subsequent modification.The contact angle value of the modified surface is 132.1°,indicating a hydrophilic surface.The electrochemical measurements and immersion tests demonstrated that the hydrophobic layer significantly improved the anti-corrosion ability of the substrate.Besides,the biocompatibility of the hydrophobic surface was examined by platelet adhesion,cytocompatibility in vitro and subcutaneous implantation in vivo.Immunological and histological results indicated that the hydrophobic layer had excellent biocompatibility.Therefore,the presented study might be a promising method for the surface modification of biomedicalmagnesium-based stent.

Preparation of phospholipid-based polycarbonate urethanes for potential applications of blood-contacting implants

Polyurethanes are widely used in interventional devices due to the excellent physicochemical property.However,non-specific adhesion and severe inflammatory response of ordinary polyurethanes may lead to severe complications of intravenous devices.Herein,a novel phospholipid-based polycarbonate urethanes(PCUs)were developed via two-step solution polymerization by direct synthesis based on functional raw materials.Furthermore,PCUs were coated on biomedical metal sheets to construct biomimetic anti-fouling surface.The results of stress–strain curves exhibited excellent tensile properties of PCUs films.Differential scanning calorimetry results indicated that the microphase separation of such PCUs polymers could be well regulated by adjusting the formulation of chain extender,leading to different biological response.In vitro blood compatibility tests including bovine serum albumin adsorption,fibrinogen adsorption and denaturation,platelet adhesion and whole-blood experiment showed superior performance in inhibition non-specific adhesion of PCUs samples.Endothelial cells and smooth muscle cells culture tests further revealed a good anti-cell adhesion ability.Finally,animal experiments including ex vivo blood circulation and subcutaneous inflammation animal experiments indicated a strong ability in anti-thrombosis and histocompatibility.These results high light the strong anti-adhesion property of phospholipid-based PCUs films,which may be applied to the blood-contacting implants such as intravenous catheter or antithrombotic surface in the future.

Cu^(Ⅱ)-loaded polydopaminecoatingswith in situ nitric oxidegenerationfunctionforimproved hemocompatibility

NO is the earliest discovered gas signal molecule which is produced by normal healthy endothelial cells,and it has many functions,such as maintaining cardiovascular homeostasis,regulating vasodilation,inhibiting intimal hyperplasia and preventing atherosclerosis in the blood system.Insufficient NO release is often observed in the pathological environment,for instance atherosclerosis.It was discovered that NO could be released from the human endogenous NO donor by many compounds,and these methods can be used for the treatment of certain diseases in the blood system.In this work,a series of copper-loaded polydopamine(PDA)coatings were produced through self-polymerization time for 24,48 and 72 h.The chemical composition and structure,coating thickness and hydrophilicity of the different copper-loaded PDA coatings surfaces were characterized by phenol hydroxyl quantitative,X-ray photoelectron spectroscopy,ellipsometry atomic force microscopy and water contact angles.The results indicate that the thickness and the surface phenolic hydroxyl density of the PDA coatings increased with the polymerization time.This copperloaded coating has glutathione peroxidase-like activity,and it has the capability of catalyzing NO releasing from GSNO.The surface of the coating showed desirable hemocompatibility,the adhesion and activation of platelets were inhibited on the copper-loaded coatings.At the same time,the formation of the thrombosis was also suppressed.These copper-loaded PDA coatings could provide a promising platform for the development of blood contact materials.

Copper-mediated polyurethane materials with enzyme-like catalysis for biocompatibility improvement in blood environments

Because of their good performance,including biocompatibility and mechanical proper-ties,polyurethanes(PUs)are widely used in medical devices.However,undesired compatibility troubles,including thrombus,inflammation,and hyperplasia,still limit the applications of PUs.In this study,copper-mediated polyurethane(PU-Cu)materials with enzyme-like catalysis were prepared.The PU-Cu materials effectively catalysed the nitric oxide(NO)released from endogenous NO donors because of the glutathione peroxidase(GPx)-like function of copper ion.The PU‐Cu materials were respectively evaluated via platelet adhesion and endothelial cell(EC),smooth muscle cell(SMC),and macrophage(MA)cultures.Scanning electron microscopy results showed that PU-Cu materials significantly inhibited platelet adhesion and activation.Meanwhile,PU-Cu materials not only promote the proliferation of EC but also inhibit SMC growth.Moreover,MA culture results intuitively stated the anti-inflammatory ability of PU-Cu.In addition,experimental samples were implanted into the subcutaneous tissue of Sprague Dawley rats.The anti-inflammatory function of PU-Cu was further confirmed by haematoxylin-eosin staining results.With regard to their excellent biological performance,PU-Cu materials are proposed for biocompatibility improvement of blood-contacting mate-rials,which should in turn provide new ideas for advanced medical devices.