Medical polymer materials

Materialproperties

Accordingtothematerialproperties,medicalpolymermaterialscanbedividedintotwocategories:non-degradableandbiodegradable.Amongthem,non-biodegradablematerialsinclude:polyethylene,polypropylene,polyacrylate,aromaticpolyester,siliconerubber,polyurethane,polyetheretherketone,etc.,whichcanremainstableforalongtimeinaphysiologicalenvironmentwithoutdegradation,crosslinkingandPhysicalwear,etc.,andhasgoodmechanicalproperties.Thistypeofmaterialismainlyusedfortherepairofhumansoftandhardtissuesandthemanufactureofartificialorgans,artificialbloodvessels,contactlensesandadhesives.Biodegradablebiomaterialsinclude:collagen,aliphaticpolyester,chitin,cellulose,polyaminoacid,polyvinylalcohol,polylacticacid,polycaprolactone,polyphosphazene,etc.Thesematerialscanbestructurallydamagedinthephysiologicalenvironment,Andthedegradationproductscanbeabsorbedorexcretedbythebodythroughnormalmetabolism,mainlyusedfordrugreleasecarriersandnon-permanentimplanteddevices.

Basicrequirements

Medicalpolymermaterialsaremostlyusedinthehumanbody,whicharedirectlyrelatedtohumanlifeandhealth.Thegeneralperformancerequirementsare:①Safety:itmustbenon-toxicorside-effectsVeryrarely.Thisrequireshighpolymerpurity,averycleanproductionenvironment,lessresiduesofpolymerizationadditives,andappmlevelofimpuritiestoensuredisease-freeandnon-toxictransmissionconditions.Atthesametime,thepolymercompounditselfandmonomerimpurities,degradationorabrasionproductsdonothaveadverseeffectsonthebody.②Thephysical,chemicalandmechanicalpropertiesneedtomeettherequirementsofmedicaldesignandfunction.Suchashardness,elasticity,mechanicalstrength,fatiguestrength,creep,abrasion,waterabsorption,dissolution,enzymeresistanceandinternalaging.Taketheheartvalveasanexample,itisbesttobeusedfor250,000hours,requiringparticularlygoodfatiguestrength.Inaddition,itisalsorequiredtobeeasytosterilizeandbeabletowithstandmoistheatsterilization(120-140°C),dryheatsterilization(160-190°C),radiationsterilizationorchemicaltreatmentsterilization,withoutreducingtheperformanceofthematerial.Medicalpolymermaterialswithdifferentpropertiescanbesterilizedaccordingtotheirspecificconditions.③Adaptability:includingadaptabilitytoothermaterialsinmedicalsupplies,biocompatibilityofthematerialwiththehumanbody,bloodcompatibilityandtissuecompatibility.Afterthematerialisimplantedinthehumanbody,itisrequiredtohavenoeffectonbodyfluidsforalongtime;goodcompatibilitywithblood,nodamagetobloodcomponents,nocoagulation,nohemolysis,nothrombosis;noforeignbodyreaction,notissuedamageinthehumanbody,nocarcinogenesisTeratogenic,willnotcauseinflammation,necrosis,tissueproliferation,etc.④Specialfunctions:Differentapplicationfieldsrequirematerialstohavecertainspecialfunctions.Forexample,filtermembranesforartificialkidneyswithseparationanddialysisfunctions,gasexchangemembranesforartificiallungs,andgas-absorbentmaterialsforartificialblood,allrequiretheirownspecialseparationandpermeationfunctions.Inmostcases,thesurfacechemicalcompositionandstructureofexistingpolymermaterialsaredifficulttomeettheaboverequirements,andsurfacemodificationtreatmentssuchasgraftcopolymerizationareusuallyusedtoimprovetheiranticoagulantproperties.Inaddition,medicalpolymermaterialsalsoneedexcellentprocessingandmoldability,andcanbeeasilyprocessedintotherequiredcomplexshapes.

Overviewofdevelopment

In1949,theUnitedStatesfirstpublishedaprospectivepaperonmedicalpolymers,andintroducedtheuseofpolymethylmethacrylate(PMMA)asahumanskullforthefirsttime.,Jointsandfemurs,theclinicalapplicationofpolyamidefibersassurgicalsutures.Inthe1950s,siliconepolymerswereusedinthemedicalfield,greatlyexpandingtheapplicationrangeofartificialorgans,includingorganreplacementandplasticsurgery.Inthe1950s,alargenumberofartificialorgansweretestedclinically,suchasartificialurethra(1950),artificialbloodvessel(1951),artificialesophagus(1951),artificialheartvalve(1952),artificialheartandlung(1953),ArtificialHeartandLung(1953),ArtificialJoint(1954)andArtificialLiver(1958),etc.Inthe1960s,medicalpolymermaterialsbegantoenteranewperiodofdevelopment.Atpresent,themoresuccessfulartificialorgansmadeofpolymermaterialsincludeartificialbloodvessels,artificialesophagus,artificialurethra,artificialheartvalves,artificialheartvalves,artificialjoints,artificialbones,andplasticmaterials.

Uses

Medicalpolymermaterialsrefertopolymermaterialsusedtomanufacturehumaninternalorgans,externalorgans,pharmaceuticaldosageformsandmedicaldevices.

Accordingtotheirspecificuses,theycanbedividedinto:(1)Materialsthatdonotdirectlycontactbiologicaltissues;suchaspharmaceuticalcontainers,plasmabags,bloodtransfusionequipment,syringes,laboratorysupplies,operatingroomsupplies,etc.;(2)Materialsincontactwithskinandmucousmembranes,suchassurgicalgloves,anesthesiasupplies(oxygentube,mask,trachealintubation,etc.),diagnosisandtreatmentsupplies(eyewashappliances,otoscopes,tonguedepressors,enemaappliances,intestines,stomach,Esophagealspeculumcathetersandprobes,portalmirrors,urinarycatheters,etc.),bandages,adhesiveplasters,etc.andhumancosmeticrepairmaterials(prostheses,ears,eyes,noses,etc.);(3)Short-termcontactwithhumantissuesMaterialssuchasartificialbloodvessels,artificialhearts,artificiallungs,artificialkidneys,dialysismembraneartificialskin,etc.;(4)Materialslong-termimplantedinthebody,suchashydrocephalusspinalfluiddrainagetubes,artificialbloodvessels,artificialvalves,artificialTrachea,artificialurethra,artificialbones,artificialjoints,surgicalsuturesandtissueadhesives,etc.;(5)Pharmaceuticalpolymers,includingmacromoleculardrugsandpharmaceuticalpolymers.Macromoleculardrugsrefertothemacromolecularizationoftraditionalsmall-moleculedrugs,suchaspolypenicillin;pharmaceuticalpolymersrefertopolymersthathavepharmacologicalfunctions,suchasanionicpolymer-typeinterferoninducers.Medicalpolymermaterialsfordifferentpurposesneedtoselectsuitablematerialsaccordingtotheuseenvironmentandthephysical,chemicalandbiologicalperformancerequirementsofthematerials.

Commontypes

Thefollowingisabriefintroductiontocommonlyusedmedicalpolymermaterials:

Chitin

ChitiniswidelyusedinlowTheshellsofcrustaceanssuchasplantfungi,shrimps,crabs,insects,etc.,arethesecondlargestrenewableresourceontheearthaftercellulose.Itisalinearpolymerpolysaccharideandtheonlynitrogen-containingalkaline.Polysaccharides.Chitinhasexcellentbiocompatibility,biologicalactivityandbiodegradability.Ithasthefunctionsofanti-inflammatory,hemostasis,analgesicandpromotingthegrowthofbodytissues,andcanpromotewoundhealing.Inaddition,chitinanditsderivativesalsohavemedicalandhealthcarefunctions,suchasimmuneregulation,loweringcholesterol,antibacterial,andpromotingthegrowthoflacticacidbacteria.Ithasextensiveresearchandapplicationinthefieldsofdrugcarriers,artificialskin,surgicalsuturesandsoon.

Collagen

Collagenisthemostabundantandwidelydistributedproteininanimals,accountingfor25%-30%ofthetotalproteininmammals.ItisthefourlargestextracellularmatrixOneofthecomponents,widelydistributedinconnectivetissue,skinbones,visceralcellinterstitiumandmusclecavity,ligaments,scleraandotherparts.Becausecollagenisamacromolecularproteinwithgoodphysicalandchemicalpropertiesandexcellentbiologicalproperties,itiswidelyusedinsurgicalsutures,hemostaticmaterials,wounddressings,artificialskin,drugcontrolledreleasecarriers,tissueengineeringandotherfields.

Siliconerubber

SiliconerubberisakindoflinearhighmolecularweightpolyorganosiloxanewithSi-O-Siasthemainchain.Afterprocessingaccordingtocertaintechnologicalrequirements,itismadeintoarubberyelastomerwithcertainstrengthandelongation.Siliconerubberhasgoodbiocompatibility,bloodcompatibilityandtissuecompatibility,isimplantedinthebody,hasnotoxicsidereactions,iseasytomoldandprocess,andissuitableformakingvariousshapesoftubes,sheets,andproducts.ItiscurrentlymedicallyhighAmongthemolecularmaterials,itisthemostwidelyusedandcanbasicallymeettherequirementsofdifferentapplications.Specificapplicationsinclude:venouscannula,dialysistube,urinarycatheter,chestdrainagetube,bloodtransfusion,infusiontube,andmainmedicalplasticsurgerymaterials.

Polylacticacid

Polylacticacidisatypeofpolymerchemicallysynthesizedwithlacticacidorlactideasmonomers.Itisabiodegradablethermoplasticpolyesterandisnon-toxicandnon-irritating.,Syntheticbiodegradablepolymermaterialwithgoodbiocompatibility,biodegradableabsorption,highstrength,andplasticprocessing.Thedegradationproductsarelacticacid,CO₂andH₂O.ApprovedbytheFDA,itcanbeusedaspharmaceuticalmaterialssuchassurgicalsutures,microcapsulesforinjection,microspheresandimplants.

Polyurethane

Polyurethanereferstoapolymercontainingcarbamategroupsonthemainchainofapolymer,referredtoasPU,whichismadebythestepwisepolymerizationofisocyanateandhydroxyloraminocompounds.Themolecularchainiscomposedofsoftandhardsegments.Polyurethanehasamainphysicalstructurefeatureisthemicrophaseseparationstructure.Itsmicrophaseseparationsurfacestructureissimilartothatofbiofilms.Duetothedifferentsurfacefreeenergydistributions,itimprovesthematerial'sadsorptiontoserumproteinsandinhibitsplateletadhesion.Goodbiocompatibilityandbloodcompatibility.Atpresent,medicalpolyurethaneisusedinthefieldsofartificialheart,heartbloodcatheter,bloodvesselcoating,artificialvalveandsoon.

Furtherreading

[1]XuXiaoyu.Biomaterials.Beijing:SciencePress,2006.

[2]ShiShuxian.Preparationandprocessingofbiomaterials.ChemicalIndustryPress,2009.