ALVES, W. F.

CORREA, A. A.

HERRMANN JUNIOR, P. S. de P.

MANZOLI, A.

STEFFENS, C.

RCAAP - Repositório Científico de Acesso Aberto de Portugal

The anion effect in the developing disposable sensor using line patterning technique of graphite [PTu63].

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the potential range was -300 to 300 mV. trntiallv phenol was used as phenolic compound.During the studies of filrn's formations an increase in each bilayer formed with PAH andTyr could be observed thus it is concluded that the enzvrne's films were deposited andwas possible to apply this in a biosensor. An increase in the reduction current with theincrease of the phenol concentrations in the electrochemical measurements could be ob-served which is attributed to efficient catalytic reaction [6]. A calibration curve (with sevenpoints) with r= 0,998 for the concentration range of phenol between 50 IJmol/L to 3,5 x 10·4 mol/L was obtained. As observed, the biosensor studied exhibits a good potential for de-tection of phenolic compounds and the layer-by-Iayer technique seerns to be suitable forimmobilization of enzymes into the nanostructured thin filrns. Authors thank also CAPES,CNPq, DQ-UFSCar and Embrapa Instrumentação Agropecuária - Laboratório Nacional deNanotecnologia para o Agronegócio for the given supports. e-mail: bello@ufscar.br[1]-MerkociA. PumeraM, LlopisX. PérezIl d,ValleM., AlegretS.:TrendsinAnaLChern. /11.9 (20051.[2]- Pérez8, PumeraM..deiValleM .MerkoçiA.,AlegretS.:J Nanosci.Nanotech.~'. II(2005] [3]-AdeyojuO.. IwuokaEJ, SmythMil.LeechO.:Analyst.121,188511996)[4]- LiJ, 1:111'LS.,GohN.K, TanS.N.:AnaLChim.Acta,30/. :1111998).[5]-Oecher.G, Hong,JO. MacromoL1,11'MacromolSymp.,46,321 (1991) [6]·daCruI VIIII •L,FatibelloFilho,O: AnaLLett, 30 15).89511'1'1/1Ackno,viedgement Thisworkhasbeendali" 111"htheWARMERresearchproject,FP6-034472DEVELOPMENT OF SENSORS CONSTRUCTED BY INTERDIGITATEDPATTERNS OF GRAPHITE DEPOSITED ON VELLUM PAPER USINGSUPERCRITICAL FLUID [RTuM6)The development of cheap and disposable senso r technology is considered a importantissue since it can be built with low cost and used for many different applications, as forexample agriculture, environmental monitoring and medical applications. The line-pattem-ing method with graphite and conductive polymers is a technique that can be useful to bea "throw-awav" electronic device, as for example electronic noses, biosensors and elec-tronic tongues. Supercritical CO2 (SC CO2) has been extensively studied for chemical reac-tions, material synthesis and phase separations due to its no toxic characteristic, whichminimizes the liquid residues problem. SC CO2 has low viscosity, high diffusivity and zerosurface tension. In this work, sensors were constructed by using interdigitated patterns ofgraphite [1 J. deposited on paper and coated with a thin film of polyaniline (PANI) in the em-eraldine oxidation state doped with DBSA (dodecylbenzenesulfonic acid) using supercriti-cal fluid. These results were compared with sensor coated with thin film of PANI dopedwith HCI produced by "in situ" polymerization. The resistance of the sensors was mea-sured in static laboratory air and in flow of drv nitrogen at room ternperature. alternatingly,and this procedure was repeated three times during 60 minutes (10 minutes each mea-surement). According to this procedure, the sensitivity and reprodutibility of each sensorwere evaluated. These results showed a different behavior between the sensors obtainedby SC CO2 and "in-situ" polymerization. The resistance measured in the SC CO2 sensor,when it was exposed into flow drv nitrogen, decreased with the time, and, on the otherhand, the opposite effect was observed using the other senso r. It can be verified that bothsensors presented good reproducibility (96%) and sensitivity (15.5%) when exposed tothe different gaseous conditions. In this way, both sensors can be used to detect volatileorganic composites, but the SC CO2 sensor has demonstrated a longer lifetime than theother senso r. Acknowledgemonts CNPq, CAPES, FAPESP.Clarice Steffens (URI/Brazil), AlexandraManzoli (Embrapa/Brazil), Elton hencesctu(URI/Brazil), José Vladimir Oliveira (URI!Brazil), Fernanda C. Corraza (URI/Brazil), M fCorraza (URI/Brazil), Paulo Sergio de Pauli!Herrmann Junior (Embrapa/Brazil)[1] [ C.Venancio, L. H. C.Mattoso, P. S.de P. HerrmannJr and A. G.MacOiarmid.Sensorsand Actuators B: Chemical, 130(2008) 723.THE ANION EFFECT IN THE DEVELOPING DISPOSABLE SENSORUSING UNE PATTERNING TECHNIQUE OF GRAPHITE [PTu63)The polvaruhnes is a class of polymer whose bigger difference in relation to other conduct-ing polymers, which is vou're doping mechanism [1]. The doping process of the polyanilinedoes not demand oxidereduction reactions. being enough only to the use of a protonicacid, With this a great variety of acid has been used. Moreover, the counterions. of the dop-ants, can infer to polymer the capacity to recognize chemical species of interest, as volatileorganic compounds (VOCs) and water vapor (relative humidity (RH)), making with that itselectric resistance change due to the interaction between the sample. This has been a usedstrategy in the development of chemical sensors based in polyaniline (PANI) for substancessuch as ammonia, hydro-carbons, and acetone and also humidity. In comparison with mostof the commercially available sensors, based usually on metal oxides and operated at hightemperatures, the disposable sensors made of conducting polymers, using line patterningtechnique [2] have many improved eharacteristics. They have good sensitivities and shortresponse time; especially, these characteristic are ensured at room ternperature. In thiswork was investigated the influence of different dopants, such as hydrochloric acid (HCI).methanesulfonie acid (MSA), p-toluenesulfonic acid (TSA) and eamphorsulfonic acid (CSA)on the electrical properties of sensors made of thin films of polyaniline. These sensors wereeonstructed by using line patterning teehnique (LPT). to developed interdigitated patterns ofgraphite deposited on vellum paper and eoated with a thin filrn of condueting polymers. Thesensors were coated with thin film of PANI doped with HCI by "in situ" polymerization meth-od. in the emeraldine base. Then, this sensors were dedoped in NH4C1 0.1 M solution andthen redoped with the desired dopant by anion replacement The resistance of the sensorswas measured in, alternating, statie laboratory air (10 minutes) and in flow of dry nitrogen(10 minutes) at room temperature, repeating this procedure three times. According to thisprocedure, the sensibility (S %) and reversibility (n %) of each senso r were evaluated, whoseresults are listed in the Table I. Can be observed that was obtained an excellent reversibilityAlexandra Manzali (Embrapa/Brazil),Alessandra Alves Correa (Embrapa/Brazil),Clarice Steffens (URI/Brazil), Wil/iam Fetteu«Alves (Embrapa/Brazil), Paulo Sergio de Péll//dHerrmann Junior (Embrapa/Brazil)to ali sensors evaluated. The results showed how the dopants have an important rule in thedevelopment of disposable sensor. In this investigations was used a flow of dry nitrogen. toevaluate the response to water vapor. It can be noted that the initial responses to flow of drynitrogen was very rapid. Acknowledgements CNPq, CAPES, FAPESP.Poni.flCI Poni·TSA. POlli·CSAPOlli-MSAS ('.)lI!" )179518100109877100[1] A.G. MacOiarmid, Synthetic Metais,84 (1997) 27. [2] E.C.Venancio, L H. CMattoso, P. S. de P. HerrmannJr and A.G. MacOiarmid, Sensorsand Actuators B:Chemical. 130 (2008) 723.DEVELOPMENT OF ELECTROCHEMICAL BIOSENSOR BASED ONLECTIN AND POLYVINYL BUTYRAL FOR EVALUATION OF SERUMGLYCOPROTEINS FROM PATIENTS INFECTED BY DENGUE [PTh56]Biosensors are great interesting because of their potential utility as specific. sim pie, label-free and direct detection techniques and reduction in size costs and time of analysis com-pared with conventional bioassay techniques. In the present work, we have introduced anovel approach for fabrication of biosensor based on immobilization on electrode surfacemodified with gold nanoparticles (nanoAu) and polyvinyl butyral (PVB) nanoAu-ConA-PVB.This system was applied as a biosensor to glycoproteins serum (GS) from patients in-fected by dengue fever (DF) and dengue hemorrhagic fever (DHF). Electrochemical im-pedance spectroscopy (EIS), in the frequency range from 100 mHz to 100 KHz, and cyclicvoltammetry (CV), from -0.2 to 0.7 V, were performed, in phosphate buffer (PBS) solutioncontaining 10 mM ~[Fe(CN)6]1K4[Fe(CN)6] (1: 1) mixture as a redox probe. In the EIS studv.an obvious difference of the electron transfer resistance between the nanoAu-ConA-PVB-BSA and nanoAu-ConA-PVB-BSA-GS (DF or DHF) modified electrodes were observed. Theimpedance spectra showed an increase in the charge transfer resistance when ConA in-teracted with GS. The cyclic voltammogram tends to be more irreversible with gradual in-crease of adsorption on the electrode surface. The resulting biosensor exhibited differentinteractions to DF and DHF.841 O.•..c:lU...... -4::lU-8-12-0.2 0.0• nanoAu-Con Ao nanoAu-ConA-PVB-BSA0.4 0.60.2 0.8Potential (V)Figure 1- C~lic voltarrmograms (CVs) of lhe electrode ai differenl stages. S,""portingelectrolyte 10 mM K,[Fe(CN),JIK,[Fe{CN).] 1:1 .•. 0.15 M NaCI in 10 mM pH 7.4 solution;sean raie. 50 mv.s'.1.0x10' -,--------------------,8.0x10·Gold barenanoAu-ConA-PVBA nanoAu-ConA-PVB-BSA.• nanoAu-ConA-PVB-BSA-DF (1:10)Ê 6.0x10·s:O- .: 4.0x10N...•. .•...•. ..• .•..•. .•.•~ ...I _T ~.JI. ÂI.,~~"0.0 "rJ--~2.0x10·0.0 2.Ox10· 4.0x10· 6.0x10· 8.0x10· 1.0x10'Z' (ohm)Figure 2- The impedance spectra were laken in 10 mM K,[Fe(CN),JIK,[Fe(CN).l1:1.•. 0.15 M N.CI in 10 mM pH 7.4 in lhe frequencyrange frem 100mHz 10100 kHz.Maria Daniellv Lima de Oliveira (UniversidadeFederal de Pemambuca, Brazil). Maria Terezados Santos Correia (Universidade Federal dePemambuca, Brazil), Flamarian Barges Diniz(Universidade Federal de Pemambuco, Brazi/)II,II"!I·li,- :1.

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The anion effect in the developing disposable sensor using line patterning technique of graphite [PTu63].

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