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AvailableonlineatAssociationoftheChemicalEngineersAChE

www.ache.org.rs/CICEQ

ChemicalIndustry&ChemicalEngineeringQuarterly14(4)219221(2008) CI&CEQ

219

MIRJANA KOSTI1NINA RADI2BRATISLAV M. OBRADOVI2SUZANA DIMITRIJEVI1MILORAD M. KURAICA2PETAR KUNDRI11Faculty of Technology andMetallurgy, University of Belgrade,Karnegijeva 4, 11000 Belgrade,Serbia2Faculty of Physics, University of

Belgrade, Studentski trg 12, 11000Belgrade, SerbiaSHORT COMMUNICATION

UDC 664.01.3/.8:664.656

ANTIMICROBIAL TEXTILE PREPARED BYSILVER DEPOSITION ON DIELECTRICBARRIER DISCHARGE TREATEDCOTTON/POLYESTER FABRICThe objective of this researchwas to impart the additional valueoncotton/

/polyester(Co/PES)fabrics(i.e.antimicrobialproperties)toimprovethequality

oflifeandthustotapnewmarketswiththeproduct.Inthispaper,silverions

were incorporated inCo/PES fabrics by chemisorptions into the fabric pre-

viouslytreatedinadielectricbarrierdischarge(DBD).AseriesoftheDBDfab-

rictreatmentsweredoneinordertodeterminethemostsuitableexperimental

conditionsfortheDBDactivationofthefabricsurface,whiletheoptimalcon-ditionsforsilverionssorptionbyCo/PESfabricsweredeterminedbychanging

sorption conditions. Theantimicrobial Co/PES fabrics prepared by dielectric

barrier discharge mediated silver deposition show an antimicrobial activity

against tested pathogens:S.aureus, E.coli,and C.albicansunder invitro

conditions.Theobtainedresultsconfirmthepracticabilityoftheplasmamodifi-

cationprocessandfurthermoreshowthatwithsomedelaysinthenextstep,

i.e.silver ion sorption,wecanget the increasein the amount ofthesorbed

silver ions; the maximumsorptioncapacity ofmodifiedCo/PES fabrics was

0.135mmolofAg+ionspergramofafabric.

Keywords:antimicrobialtextiles;cotton/polyesterfabric;dielectric-bar-rierdischarge;silverions;antimicrobialtesting.

It has long been recognized that micro orga-nismscangrowontextilesubstrate.Onewaytoavoidthemicrobialdegradationoftextilefibers,limitthein-cidence of bacteria, and protect users, is the treat-mentoftextileswithantimicrobialagents[1,2].Silverinvariousformshasalonghistoryasanantimicrobialagentandsilver-loadedfibersdeservespecialatten-tionduetosomeuniqueproperties,whichdifferenti-ate silver from other antimicrobial additives, namelyitsinherentpropertiesofhighthermalstability,broadandlong-termactivity;bacteriaarenotabletodeve-

loptheirresistancetothesilver,asinthecaseofanti-biotics;anditisoneofafewantimicrobialprepara-tions which possess both the antibacterial activitiesandantifungalproperties[3,4].

Thereare numerousways bywhich antimicro-bialpropertiescanbeaccomplishedintextiles:thein-corporationofantimicrobialagentsdirectlyintofibers, Corresponding author: M. Kosti, Faculty of Technology andMetallurgy, University ofBelgrade,Karnegijeva 4, 11000 Bel-grade,Serbia.E-mail:kostic@tmf.bg.ac.yuPaperreceived:October09,2008.

Paperrevised:October29,2008.Paperaccepted:October30,2008.

coating or adsorbingantimicrobials onto fiber surfa-ces, theimmobilization ofantimicrobials tofibers byionorcovalentlinkages, etc.Amongallthese,plas-ma-basedtreatmentsusedtocreateantimicrobialco-atingsontextiledeservespecialattentionduetosomeuniquepropertiesandgrowingdemandsontheenvi-ronmentalfriendlinessoffinishingprocessesforsur-facemodificationandcoatingoftextiles[5,6].

The objective of this research is to impart theadditionalvalueoncotton/polyester(Co/PES)fabrics(i.e., antimicrobial properties), to improve thequality

oflifeandthustotapnewmarketswiththeproduct.Inthisresearch,silverionswereincorporatedintoCo/PESfabricpreviouslytreatedinadielectricbarrierdischar-ge(DBD).AseriesoftheDBDfabrictreatmentsweredone inorder todetermine themostsuitableexperi-mentalconditionsfortheDBDactivationofthefabricsurface, while the optimal conditions for silver ionssorptionbyCo/PESfabricsweredeterminedbychan-gingsorptionconditions.Antimicrobialactivityofmo-difiedCo/PESfabricsagainstdifferentpathogenswasevaluatedinvitro.

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EXPERIMENTALThe tested fabric was a commercial Co/PES

fabric,consistingof50%cottonand50%polyester,plainweave,withafabricweightof250g/m2anda

thicknessof0.68mm.Allchemicalsusedarep.a.grade.Inthiswork,DBDwithplane-parallelelectrodes

(8.08.0 cm) for operation in ambient air at atoms-pheric pressurewas used. The configurationof theelectrodesispresentedinFigure1.Sphericalzeolitegranules cover the bottom electrodeof the DBD, inone layer, to avoid problems with humidity and tomaintainahomogeneousdischarge[7].TheCo/PESfabricsample strips(1580mmlong,inwarpdirec-tion)weretreatedusingtheDBDsfordifferentperiodof time (up to 120 s). Antimicrobial Co/PES fabricswereobtainedbysilverionsorptionfromaqueoussil-

vernitratesolution;thesubsequentsilversorptionbyplasma treated fabrics has taken place immediatelyaftertheDBDtreatmentorafter1,3,and7daysofaging.TheamountofsorbedAg+wasdeterminedbythe back titrationaccordingto Volhardsmethod [8].Agardiffusiontestwasusedtoassesstheantimicro-bial activity of silver - loaded cotton/polyester fabric[9,10]. Three test organismswere used:Gram-posi-tiveStaphylococcus aureus ATCC25923,Gram-ne-gativeEscherichiacoliATCC25922,andyeastCan-didaalbicansATCC24433.

Figure1.Theconfigurationoftheelectrodes.

RESULTS AND DISCUSSIONSPlasmasurfaceactivationisinitiatedbyradical

reactionsoftheplasma-activatedgasesorplasmage-nerated UV-irradiation. The modification of a textilesurfacebyatmospheric-pressureDBDplasmasmainlydependsonthegasnatureandtheexposuretime.Inthis study, the air was chosen as the operating gasbecauseoftheeconomicreasonandthereactivityoftheoxygen(i.e.,themolecularoxygenintheaircanbeconvertedintoreactiveatomicoxygenradicalsorexcited ozone molecules), and the surface modify-cationinducedonCo/PESfabricsbyDBDtreatmentwasinvestigatedasafunctionoftheexposuretime.

Thesilverionsorptionusedtoobtainantimicro-bialfabrics,wasalsousedasameasureofthesur-faceactivationofDBDmodifiedfabrics,whichisdi-rectlyrelated tothe surface ionexchangefunctions.Because of the common observation that the che-micalandphysicalactivityoftheplasmaactivatedpo-lymeric surfaces diminishes with time [11,12], thesubsequentsilversorptionbyplasmatreatedfabricshastakenplaceimmediatelyaftertheDBDtreatmentorafter1,3,and7daysofaging(Figure2).Inthatwayweevaluatedthepracticabilityoftheprocessbe-causeithastobetoleranttoshortstoragetimesandtypicaldelaysinthemanufacturingprocess.

0 1 2 3 4 5 6 7 80,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

Ag

+s

orption,mmol/g

Aging, day

0 s

30 s

60 s

120 s

Figure2.Theeffectsoftheplasmaexposuretimeandagingon

Ag+sorptionbyDBDactivatedCo/PESfabrics(sorption:RT,4h,

pH5.1,0.01MAgNO3).

Co/PES fabrics treated inDBD possess highlyimprovedsorptionproperties.Theobtainedsilverionuptakes immediately after plasma treatments were100%higher than the silver ion uptake of an un-modifiedfabric,asshowninFigure2.However,thereisnoclearexposure time dependant silver ions up-takeundertheappliedexperimentalconditions.Atthesame time, the silver ion uptake of the agedDBD

treated samplesgradually increased for about50 to100%withtheagingtime,upto7daysofaging.TheobservedincreaseoftheamountofsilverionssorbedbytheagedDBDtreatedCo/PESfabricscanbeex-plainedbypost-plasmareactions( i.e.,furtheroxida-tion of the carbonyl to the carboxyl function) gene-ratedbyquitestableradicals[7,12,13].

Theeffectofthecontacttimeonthesilverionsuptakewasstudieduptoacontacttimeof4h(Figure3).ThefastsorptionofAgionswasobservedinthefirst60min;approximatelymorethan90%ofthetotalup-

takecapacityofsilverionswassorbedwithinthispe-riodoftime.Thegenerallyfastsorptionsindicatethat

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reactions at outer surfaces are important. After thisequilibriumperiodtheamountofsorbedsilverionsdidnotchangesignificantlywithanincreaseincontacttime.

0 50 100 150 200 250

0,00

0,02

0,04

0,06

0,08

0,10

Ag

+s

orption,mmol/g

t, min Figure3.KineticsofAg+sorptionby60sDBDmodifiedCo/PESfabric immediately after the treatment (sorption: RT, pH 5.1,

0.01MAgNO3).

TheresultsofantimicrobialtestsgiveninTable1showthattheincorporationofsilverionsinCo/PESfabricleads to the generation ofantimicrobialmate-rialshavingtheactivityagainstabroadspectrumofmic-robes (Gram-negativebacteria strains E.coli,Gram-

-positivebacteriastrains S.aureus,andyeastC.albicans). These fabrics indicate a different activityagainstdifferentmicro-organisms;theyeastC.Albi-cans,isthemostsensitivetothesilver-loadedCo/PESfabrics.Also,thereis noclear dosedependant anti-microbial activity but the quantity of bonded silverions,inallcases,isenoughtodevelopadesirablean-timicrobialactivityinthesilver-loadedCo/PESfabrics.

Table1.Antimicrobialactivityofthesilver-loadedCo/PESfabrics

Widthoftheinhibitionzone+suppressionzonemmSample

DBDexposuretime,s

Ag+sorption,mmol/g S.aureus E.coli C.albicans

Co/PES 0 0 0 0 0

Co/PES+Ag

0 0.045 0.7 0.7 0.7

Co/PES+Ag*

30 0.073 1.0 0.5 2.0

Co/PES+Ag*

60 0.073 1.0 0.7 2.5

Co/PES+Ag*

120 0.072 1.3 1.0 2.7

Co/PES+Ag**

120 0.135 1.0+2.5 2.5+2.5 2.5

*Ag+sorptionimmediatelyaftertheDBDtreatment;**Ag+sorptionafter7

daysofaging

CONCLUSIONSThe antimicrobial Co/PES fabrics prepared by

dielectricbarrierdischargemediatedsilverdepositionshow the antimicrobialactivity against tested patho-

gens:S.aureus,E.coli,andC.albicansunderinvitroconditions.Theobtainedresultsconfirmthepractica-bility of the plasma process in the activation of thefabricsurface and furthermoreshow thatwith somedelaysinthenextstep, i.e.silverionsorption,wecanget the increase in the amount of the sorbed silverions; the maximum sorption capacity of modifiedCo/PESfabricswas0.135mmolofAg +ionspergramofafabric.

AcknowledgmentThe support of the Ministry of Science and

TechnologicalDevelopmentoftheRepublicSerbiaisgratefullyacknowledged.

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