AnElectrochemicalSensorBasedonGold Nanodendrite ...3.7. Reproducibility, Repeatability, and...

Research ArticleAn Electrochemical Sensor Based on GoldNanodendriteSurfactant Modified Electrode for BisphenolA Detection

Nguyen Thi Lien1 Le QuocHung2 Nguyen TienHoang3 Vu Thi Thu3 Dau Thi Ngoc Nga3

Pham Thi Hai Yen2 Pham Hong Phong2 and Vu Thi Thu Ha 23

1Department of Chemistry Hanoi University of Science 19 Le anh Tong Hanoi Vietnam2Institute of Chemistry Vietnam Academy of Science and Technology 18 Hoang Quoc Viet Cau Giay Hanoi Vietnam3University of Science and Technology of Hanoi Vietnam Academy of Science and Technology 18 Hoang Quoc Viet Cau GiayHanoi Vietnam

Correspondence should be addressed to Vu i u Ha vuthithuha503gmailcom

Received 12 October 2020 Revised 30 November 2020 Accepted 14 December 2020 Published 29 December 2020

Academic Editor Tien Duc Pham

Copyright copy 2020 Nguyen i Lien et al is is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

In the present work we reported the simple way to fabricate an electrochemical sensing platform to detect Bisphenol A (BPA)using galvanostatic deposition of Au on a glassy carbon electrode covered by cetyltrimethylammonium bromide (CTAB) ismaterial (CTAB) enhances the sensitivity of electrochemical sensors with respect to the detection of BPA e electrochemicalresponse of the modified GCE to BPA was investigated by cyclic voltammetry and differential pulse voltammetry e resultsdisplayed a low detection limit (22 nm) and a linear range from 0025 to 10 microm along side with high reproducibility (RSD 49for seven independent sensors) Importantly the prepared sensors were selective enough against interferences with otherpollutants in the same electrochemical window Notably the presented sensors have already proven their ability in detecting BPAin real plastic water drinking bottle samples with high accuracy (recovery range 9660ndash10282) and it is in good agreementwith fluorescence measurements

1 Introduction

Bisphenol A (BPA) is known as a typical endocrine disruptorin the environment which is widely used in the productionof plastic products [1] As a result BPA is found in food anddrinking water from product packaging and thereforehumans may routinely ingest amounts of BPA even in tracelevels [2] So far different analytical methods have beendeveloped and used for the determination of BPA such asgas chromatography [3] high performance liquid chro-matography [4] fluorimetry [5] molecular imprinting [6]and enzyme-linked immunosorbent assay [7] Electro-chemical detection techniques have advantages in relation tothese techniques of rapidity low cost high sensitivity simpleoperation good selectivity and real-time detection with in

situ analysis [8] Recently electrochemical techniques havebeen popularly developed for BPA detection [9ndash28] espe-cially many publications focus on electrode modification inorder to enhance signals of target analytes Recently lots ofdifferent modifiers have been developed for electrochemicalsensors such as carbon blackf-MWCNT composite modi-fied glassy carbon electrode (GCE) which was used fordetection of BPA with a detection limit of 008 μmol Lminus1 [9]molybdenum disulfide nanoflower-chitosan-Au nano-particle composites [10] poly(amidoamine)ndashAuNP-silk fi-broin [29] carbon nanotubes-szlig-cyclodextrin [30] andcarboxylic group functionalized CNT-poly(3 4-ethyl-enedioxythiophene) [31] Besides that gold nanoparticles(AuNP) combined with other materials were of interest tomany researchers such as multiwall carbon nanotubes

HindawiJournal of Analytical Methods in ChemistryVolume 2020 Article ID 6693595 10 pageshttpsdoiorg10115520206693595

(MWCNT) plus AuNP modified GCE [11 32 33] becauseAu is the material with extremely high conductivity AsNajib Ben Messaoud et al [11] showed a modified electrodewas prepared by two steps drop-casting a desired amount ofMWCNTon polished GCE followed by deposition of AuNPon the surface of the previously prepared MWCNTGCEWith this sensor the detection limit of BPA reached 4 nMIn this work an electrochemical sensor for BPA detectionconsisting of gold nanodendrites (AuNDs) deposited onGCE which was precovered by cetyltrimethylammoniumbromide (CTAB) CTAB is one of the known cationicsurfactant which has been extensively employed to enhancethe sensitivity of electrochemical sensors [34 35] It is alsopresented that CTAB has a hydrophilic head on one side anda long hydrophobic tail on the other side of its moleculeAlso as reported surfactants adsorbed at the electrodesurface may alter the electrode behavior and accelerate theelectron transfer process between the analyte and theelectrode surface [36] In this context the GCE-supportedAu nanodendrites and CTAB (denoted as AuNDsCTABGCE) were demonstrated as an electrochemical sensorwhich has sensitive electrochemically active surface areasdue to the hierarchical nanodendrites structure and theformation of nanodendrite on the CTABGCE was ac-complished in just 5 minutes by simple one-step electro-deposition e electrochemical behavior of BPA on thissensor was studied by cyclic voltammetry (CV) and elec-trochemical impedance spectroscopy (EIS) and the ana-lytical measurements were performed by differential pulsevoltammetry (DPV) e AuNDsCTABGCE sensor hasbeen employed to detect BPA in aqueous samples andimportant factors related to electrochemical response suchas pH (from 50 to 90) were examined as well to get theoptimal conditions for BPA detection

2 Materials and Methods

21 Materials and Sensor Preparation Bisphenol A (BPA)was purchased from Sigma-Aldrich (Structures inFigure S1) GCE (BAS diameter 3mm) was used as acurrent collector Phosphate buffer solution (PBS) wasprepared by mixing 02M KH2PO4 and 02 MK2HPO4 untilthe desired pH (in the range from 50 to 90) was obtainedPotassium ferrocyanide trihydrate (K4[Fe(CN)6]3H2O)potassium ferricyanide (K3[Fe(CN)6]) and all reagentsneeded for the construction of Au nanodendrites HAuCl4(99999) KI H2SO4 and NH4Cl were bought from Sigma-Aldrich All chemicals were used as received without anyfurther treatments

e AuNDsCTABGCE sensor was prepared as re-ported in our previous publication [37 38] In brief 5 microLCTAB was drop-casted on GCE dried in the atmosphere inabout 2 h 30 to 3 h e dried CTABGCE was put in asolution containing 20mM HAuCl4 1mM KI 5M NH4Cland 05MH2SO4 and previous regime published by authorrsquosgroup was followed [37 38] A current of -20mA was ap-plied to it for the preparation of Au nanodendrites byelectrodeposition for 30 s AuNDsCTABGCE was rinsedthrough by a mixture of EtOH and H2O (1 3) and kept in a

desiccator overnight A scanning electronmicroscope (SEM)image of the built Au nanodendrite was obtained (S-4800Hitachi Japan) with an electron beam accelerated by avoltage of 15ndash20 kV to characterize the structure Fluores-cence spectra were obtained with a FluoroMax-4 spectro-fluorometer equipped with an Ozone-free xenon arc lamp(150W) Czerny-Turner monochromators (HORI-BAndashJapan) All measurements were performed in a 10mmquartz cell at room temperature e emission spectra arerecorded between 470 and 540 nm with the excitationwavelength at 460 nm

22 Electrochemical Measurements of Samples All of theelectrochemical measurements were conducted at roomtemperature (25degCplusmn 1) using a three-electrode system inwhich an AgAgCl electrode and a Pt wire were used as thereference and auxiliary electrode respectively A custom-made multifunctional potentiostat-galvanostat manufac-tured by this research group (Vietnam Academy of Scienceand Technology Hanoi Vietnam) was used It was equippedwith 12-byte analog-digital and digital-analog converterswith two operational amplifiers and it provided the currentresolution down to 0008 nA

DPV was used for BPA measurement with a differentialstep of 0005V a sampling time of 004 s a pulse width of008 s and a pulse amplitude of 005V e accumulationconditions of BPA onto AuNDsCTABGCE were con-ducted at i 0 (under open-circuit potential) with a durationtime of 240 s (selected from previous publications [39] andvoltammograms were recorded over a range of 025 to 085Vversus AgAgCl A PBS solution (pH 7) was used as asupporting electrolyte in all measurements

3 Results and Discussion

31 Surface Morphology of Prepared Sensors e surfacemorphology of AuNDsCTABGCE was examined using theSEM technique (Figure 1) Au nanodendrites were quicklyformed on the electrode surface after 5-minutes of elec-trodeposition When CTAB surfactant was not used theaggregation of gold nanostructures (Figure S2) and theformation of large gold branches (Figure 1(c)) were ob-served e use of CTAB has helped to limit those unwanteddefects thus significantly increased the active surface areaand providedmore access sites for analytes at not only the tipof gold brands but also inside gold branches

32 Electrochemical Performance of AuNDCTABGCEBefore using AuNDsCTABGCE prepared for detection ofBPA on GCE CTABGCE AuNDsGCE and AuNDsCTABGCE electrochemical impedance spectroscopy (EIS)was recorded in 02M PBS containing 5mM Fe(CN)63minus4minusIn the Nyquist diagram (Figure 2) the bare GCE exhibited arelatively low electron transfer resistance (Rct 1463Ω)with a small semicircle (refer to in inset for further detail)After the drop-casting CTAB and deposition of AuNDs theelectron transfer rate dramatically increased which resultedfrom a decrease of the charge transfer resistance (Rct 254O

2 Journal of Analytical Methods in Chemistry

(a) (b)

(c) (d)

Figure 1 SEM images of (a) GCE (b) CTABGCE (c) AuNDsGCE and (d) AuNDsCTABGCE samples

50 100 150 200 250 300 350

0

40

80

120

160

200

GCECTABGCE

AuNDsGCEAuNDsCTABGCE

0

70

140

210

280

350

420

490

ndashZprime (Ω

)

ndashZprime (Ω

)

100 200 300 400 500 600 700 8000ndashZPrime (Ω)

ndashZPrime (Ω)

Figure 2 Nyquist diagrams of GCE CTABGCE AuNDsGCE and AuNDsCTABGCE in the solution containing 5mM Fe(CN)63minus4minus

and 01M PBS Parameters are as follows Frequency range from 01Hz to 10000Hz initiative potential 023V amplitude 10mV and quiettime of 5 s

Journal of Analytical Methods in Chemistry 3

only) due to the high conductivity of AuNDs on the elec-trode surface Also CTAB molecules must have aided toimprove the electron transfer process of Fe(CN)63minus4minus probeat electrode surface [35] All the results further demonstratethat the electrode is well done with the presence of AuNDslayers on its surface is result is in good agreement withCV tests (Figure 3)

In Figure 3 it is seen that in a well-defined reversibleredox system with a peak separation (ΔEp) of sim80mV for allcases the CTABGCE exhibits a pretty low electron transferrate After deposition of AuNDs the oxidation peak of thisredox probe increased almost three times higher thanCTABGCE only in terms of electrical conductivity (Fig-ure 3) Also as stated in [36] CTAB can help in acceleratingthe electron transfer process between the analyte and theelectrode surface erefore the total peak current receivedon AuNDsCTABGCE was the highest

33 Effects of Scan Rate (]) Kinetics of electrochemicaloxidation of BPA on AuNDsCTABGCE was investigatedin PBS at pH 7 containing 10 microm target analyte with differentscan rates from 10 20 50 100 and 200mV sminus1 (Figure 4)Oxidation peak currents appeared at 055V and increasedlinearly with the increasing scan rate as followsipa 00316times ]+ 07415 (R2 09993) which suggests anadsorption controlled kinetic process on the modifiedelectrode surface AuNDsCTABGCE [19ndash28] As seen inFigure 4 the oxidation peak potential (Epa) slightly shiftedto more positive potentials with the increase of the scan ratee dependence between Epa and the ln(v) was givenEpa(V) 00184times ln(v)+ 04949 (R2 09969) (inset ofFigure 4(b)) and the number of electrons transferred esti-mated from Laviron quation is as follows [40]

Epa Eo

+RTαnF

1113888 1113889lnRTk

o

αnF1113888 1113889 +

RTαnF

1113888 1113889ln(v) (1)

where v is the scan rate n is the number of electronstransferred α is the electron transfer coefficient ko is thestandard rate constant of the reaction and R F and Tare gasconstant Faraday constant and absolute temperature re-spectively As the slope of the plot of Epa versus ln(v) (equalto RTαnF) is 00184 the value of αn was about 13 Alsofrom Laviron [40] α for an irreversible electrode process isassumed to be 05 erefore the number of electronstransferred (n) for electrooxidation of BPA is around 2[26ndash28]

34 Effect of pH It is known that the electrochemical oxi-dation of BPA followed a proton coupled electron transfermechanism ie BPA oxidized product + nendash + nH+ (n 1or 2) the reaction rate is directly depending on the electronflux and the concentration of proton in solution Conse-quently the pH becomes one of the key parametersimpacting the performance of the presented sensors DPVsof BPA (C 50 microm) were recorded by sweeping the potentialfrom 01Vndash09V in PBS buffer with pH ranging from50ndash90 at interval 10 It was found that the peak potential is

shifted to a more negative direction at higher pH values(Figure 5(a))

By plotting the variation of peak potential depending onpH values a linear relationship is obtained ie Ep a minus00659pH+09642 R2 09869 A slope of 0065VpH was prettyclose to the theoretical value of 0059VpH showing that thetransfer of electrons was accompanied by an equal number ofprotons in electrode reaction According to the calculation in[41] minus0065xn minus0059 where n is the transferred electronnumber and x is the number of protons involved in thereaction as mentioned above the number of electronstransferred is about 2 the electrochemical oxidation of BPA isa two-electron and two-proton process which is in goodagreement with previous publications [26ndash28] as below

OOHO OH ndash2endash

ndash2H+

35 Detection of BPA Using AuNDsCTABGCE In order tocompare electrochemical signals BPA on four materials usedfor the sensor GCE CTABGCE AuNDsGCE and AuNDsCTABGCE DPV signals were recorded in PBS pH 7 Fig-ure 6 describes peak currents of BPA on four above materialsat 10 50 and 10microm It is seen that currents measured onAuNDsCTABGCE are always highest and it is almost 10- 4- and 2-fold compared with it on GCE CTABGCE AuNDsGCE respectively Also it was observed visually that withAuNDsGCE only AuNDs layers easily sloughed from theGCE surface By measuring CVs of AuNDsCTABGCE atdifferent scan rates in 02M PBS containing 5mMFe(CN)63minus

4minus electrochemical active surface of this sensor is not asignificant difference in comparison with bare GCE(Figure S3) erefore it is assumed that the increase of peakcurrent was due to the fact that AuNDs might provide more

0

GCECTABGCE


00 02 04 06ndash 02EV vs AgAg

ndash 60

ndash 40

ndash 20

20

40

60

I (μA

)

Figure 3 CVs of GCE CTABGCE AuNDsGCE and AuNDsCTABGCE in 5mM Fe(CN)63minus and 02M PBS from minus 02 to 06Vversus AgAgCl


electroactive sites for BPA electrooxidation while CTABcould improve adherence of targeted molecules and promoteelectron transfer process at electrode surface [35]

36 Calibration Curve Figure 7(a) shows voltammogramsof all the BPA samples measured using selected AuNDsCTABGCE under optimized conditions BPA peak heightsincreased with an increase in concentrations with the re-gression equation as follows i(microA) 00012timesCBPA(microm)+0007 (R2 09996) (Figure 7(b))

e limit of detection of the sensor (LOD) was esti-mated (LOD 33 times S Db SD standard deviation of or-dinate intercept b slope of regression line) to be 22 nm forBPA in PBS (pH 7) It showed that the LOD of AuNDsCTABGCE sensor was comparable with those of otherelectrode-based sensors (Table 1) and much lower than theallowable level of BPA declared byWHO [42]e excellentperformance of AuNDsCTABGCE based sensor for BPAbenefits from the high conductivity large area of AuNDsand charge transfer promotion along long alkane chain ofCTAB [35]

CV_10μMBPA_AuNDsCTABGCE_10mVsCV_10μMBPA_AuNDsCTABGCE_20mVsvCV_10μMBPA_AuNDsCTABGCE_50mVsCV_10μMBPA_AuNDsCTABGCE_100mVs

CV_10μMBPA_AuNDsCTABGCE_200mVsCV_10μMBPA_AuNDsCTABGCE_300mVsCV_10μMBPA_AuNDsCTABGCE_400mVs

03 04 05 06 07 08 09 1002E V vs AgAgCl

ndash10

ndash5

0

5

10

15

20

25

I (μA

)

(a)

0 100 200 300 400

y = 003156x + 07415R2 = 099930

2

4

6

8

10

12

I (μA

)

V(mVs)

(b)

2 3 4Inv(mVs)

5 6

y = 00184x + 04949R2 = 09969

EV

vs

Ag

AgC

l

054

056

058

060

062

(c)

Figure 4 (a) CVs of BPA 10 microm in PBS pH 7 recorded on AuNDsCTABGCE at different scan rates (]) 10 20 50 100 and 200mVsminus1(Inset) Relationship (b) between anodic peak currents and scan rate and (c) between potentials and ln(])


37 Reproducibility Repeatability and Interference Studye reproducibility was tested using seven separated sensors(Figure S4)emagnitudes of error bars are quite small andthe average relative standard deviations (RSDs) in themeasurements of BPA were less than 50 thereby con-firming the reproducible formation of AuNDsCTAB onGCE Repeatability tests have been done with 5 consecutivemeasurements using one AuNDsCTABGCE sensor RSDsreceived for 10 microm BPA in solutions was 437 less than50 as above

Finally the selectivity of as-prepared sensors was eval-uated in the presence of Cu2+Pb2+Cd2+ and 4-nitrophenol

as interferants e concentrations of interferants weredesignedly fixed at 100 microm which is 20 times greater thanBPA concentration No significant changes in current in-tensity observed suggesting no interference effect due toother compounds in this study (Figure S5)

38 Real Sample Analysis To open the application AuNDsCTABGCEwas further used to determine BPA quantities inreal samples prepared from a plastic drinking water bottleSample preparation from plastic pieces was treated as in[43] Briefly the plastic sample of LaVie bottles a popular

0

5

10

15

20

25

30

pH 5pH 6pH 7

pH 8pH 9

I (μA

)

02 03 04 05 06 07 0801E V vs AgAgCl

(a)

0

5

10

15

20

25

30

I (μA

)

5 6 7pH

8 9

(b)

5 6 7pH

8 9

E V

vs

Ag

AgC

l

035

040

045

050

055

060

065

(c)

Figure 5 DPVs of 50 micromBPA onAuNDsCTABGCE in PBS pH 7 with different pH 50 60 70 80 and 90 (a) Currents varied by pH (b)and relationship between potentials and pH (c)


GCECTABGCE


2 4 6 8 100CBPA (μM )

0

2

4

6

8

10

12

I (μA

)

Figure 6 Peak current of BPA at 10 50 and 100 microm on GCE CTABGCE AuNDsGCE and AuNDsCTABGCE recorded in PBS pH 7

0μM0025μM005μM

01μM02μM05μM

1μM5μM10μM

04 05 06 07 0803CBPA (μM)

0

2

4

6

8

10

12

14

I (μA

)

02468

1012

I (μA

)

0 2 4 6 8 10 12ndash2CBPA (μM )

(a)

(b)

y = 00012x + 00007R2 = 09996

Figure 7 (a) Voltammograms recorded from BPA in the concentration range from 0025 to 10 microm using AuNDsCTABGCE and (b) thevariations of peak intensities according to the concentration change


commercial product in Vietnam were cut into small piecesand washed several times with double distilled water Aftervacuum drying 10 g of the plastic sample and 50mL ofpurified water were added to the flask sealed and heated at70degC for 48 hours Finally the mixture is filtered by a 45 micromfilter e as-prepared solution was divided into two partsone for fluorescence measurement and the second part forelectrochemical measurement in PBS pH 7 DPV voltam-mograms are shown in Figure S6 e emission spectra ofBPA appeared at a wavelength of 506 nm (Figure S6 (b))Table 2 shows concentrations of BPA spiked in the treatedsolution using prepared AuNDsCTABGCE and the cal-culated recoveries by both techniques

e concentration determinations using AuNDsCTABGCE were accurate with a recovery range of 9660ndash10282 ese were in agreement with data obtained usinga FluoroMax-4 spectrofluorometer erefore the detection

performance of AuNDsCTABGCE was acceptable for thispurpose

4 Conclusion

In this paper the GCE-supported Au nanodendrite andCTAB (denoted as AuNDsCTABGCE) have been devel-oped by simple one-step electrodeposition e AuNDsCTABGCE sensor was able to detect BPA in a large con-centration range (0025ndash10 microm) with a relative detectionlimit of 22 nm Sensor-to-sensor reproducibility was esti-mated by measuring seven separate prepared AuNDsCTABGCE sensors and the obtained RSDs were only lessthan 50 Real samples extracted from plastic drinkingbottles were also tested and the determined concentrationswere in good recoveries (9660ndash10282) and comparablewith other conventional methods Furthermore AuNDs

Table 1 Comparison of sensing performances of electrochemical sensors for detection of BPA

Electrode configuration Method Linear range (microm) LOD (microm) RefCBf-MWCNTs CV 01ndash130 008 [9]AuNPsMoS2GCE CV 005ndash100 5times10minus3 [10]SWCNTsCDGCE DPV 00108ndash185 1times 10minus3 [30]NPsMWCNTGCE 001ndash07 4times10minus3 [11]rGO-NiS DPV 438times10minus3ndash0438 175times10minus3 [12]Cu-BTCGCE DPV 5times10minus3ndash2 072times10minus3 [13]Fe3O4NPs-CB DPV 01times 10minus3ndash50 0031times 10minus3 [14]RGO-AgGCE DPV 1ndash80 054 [15]Rh2O3-GOGCE CV 06ndash40 012 [16]Cu-ZnGOGCE SWV 3times10minus3ndash100 and 350ndash20000 088times10minus3 [17]GO-CNTs-Fe3O4 DPV 3times10minus3ndash02 and 02ndash300 1times 10minus3 [18]CTABMWCNTsPGE SWV 2times10minus3ndash0808 0134times10minus3 [19]CSN-GSGCE CV 001ndash13 5times10minus3 [20]BmimPF6GNGCE LSV 002ndash2000 8times10minus3 [21]GAMWCNT-NH2 DPV 01ndash10 002 [22]Cu2O-rGO DPV 01ndash80 0053 [23]AuPdNPsGNs DPV 005ndash10 8times10minus3 [24]PCEPEDOTBMIMBr DPV 01ndash500 002 [25]MoS2-SPANGCE DPV 0001ndash10 06times10minus3 [26]ELDHsGCE DPV 002ndash151 68times10minus3 [27]CTABCe-MOFGCE DPV 0005ndash50 2times10minus3 [28]AuNDsCTABGCE DPV 0025ndash10 22 nM is workAuNPs gold nanoparticles CPE carbon paste electrode NPsnanoparticles ILs ionic liquids BTC benzenetricarboxylic GO graphene oxideErGO electrochemical reduced graphene oxide GCE glassy carbon electrode SWV square wave voltammetry DPV differential pulse voltammetryCV cyclic voltammetry LSV linear sweep voltammetry MWNTmultiwalled carbon nanotubes GN graphene CTAB cetyltrimethylammoniumbromide MOFmetal organic frames PGE pencil graphite electrode CS chitosan GS graphene sheet BmimPF6 -butyl-3-methylimidazoliumhexafluorophosphate

Table 2 Determined BPA concentrations spiked in the real sample using AuNDsCTABGCE and by Fluorescence methods

Sample

BPA (microm)

AddedFound Recovery ()

By AuNDsCTABGCEsensor By fluorescence By AuNDsCTABGCE

sensor By fluorescence

Solution from LaVie plasticsbottle

0 Not found Not found mdash mdash500 498plusmn 006 488plusmn 007 9953 97231000 1028plusmn 014 1023plusmn 009 10283 102261500 1449plusmn 029 1489plusmn 033 9660 9920

e recovery in each case is also shown


CTABGCE should be employable as an electrochemicalsensor for on-site water analysis with low cost and withoutthe serious worry of environmental contamination

Data Availability

e graphical abstract structure of study compound SEMimages at a larger scale CVs and DPVs of sensorrsquos repro-ducibility and real sample analysis data used to support thefindings of this study are included within the supplementaryinformation files

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is research was funded by the Institute of Chemistry(grant number VHH2020201) and the Vietnam Academyof Science and Technology (grant numbers NCVCC061020-20 and KHCBHH0119-21)

Supplementary Materials

Fig S1structure of the studied compound Fig S2 SEMimages of AuNDs created on GCE without (a) and withCTAB layer (b) Fig S3 CVs of AuNDsCTABGCE in5mM K3Fe(CN)6K4Fe(CN)6 + 02M PBS at different scanrates and used for calculation of electroactive surface area(ECSA) Fig S4 reproducibility of seven AuNDsCTABGCE sensors at 10 microm BPA in PBS pH 7 Fig S5 voltam-mograms of BPA 5 microm on AuNDsCTABGCE before andafter adding interferents at concentrations 20 times higherthan that of analyte BPA with Cd2+ Pb2+ and Cu2+ (a) andwith 4-nitrophenol (b) Fig S6 voltammograms of solutionextracted from plastic drinking water bottle spiked BPA atdifferent concentrations recorded on a AuNDsCTABGCEsensor (a) and by the fluorescence method (b) (Supple-mentary Materials)

References

[1] S H Safe ldquoEndocrine disruptors and human health is there aproblem an updaterdquo Environmental Health Perspectivesvol 108 no 6 pp 487ndash493 2000

[2] F S Vom Saal and C Hughes ldquoAn extensive new literatureconcerning low-dose effects of bisphenol A shows the need fora new risk assessmentrdquo Environmental Health Perspectivesvol 113 no 8 pp 926ndash933 2005

[3] E M Malone C T Elliott D G Kennedy and L ReganldquoRapid confirmatory method for the determination of sixteensynthetic growth promoters and bisphenol a in bovine milkusing dispersive solid-phase extraction and liquid chroma-tography-tandem mass spectrometryrdquo Journal of Chroma-tography B vol 878 no 15-16 pp 1077ndash1084 2010

[4] Y Ji J Yin Z Xu et al ldquoPreparation of magnetic molecularlyimprinted polymer for rapid determination of bisphenol A inenvironmental water and milk samplesrdquo Analytical andBioanalytical Chemistry vol 395 no 4 pp 1125ndash1133 2009

[5] Y Kim J B Jeon and J Y Chang ldquoCdSe quantum dot-encapsulated molecularly imprinted mesoporous silica par-ticles for fluorescent sensing of bisphenol Ardquo Journal ofMaterials Chemistry vol 22 no 45 pp 24075ndash24080 2012

[6] W Zhao N Sheng R Zhu et al ldquoPreparation of dummytemplate imprinted polymers at surface of silica micropar-ticles for the selective extraction of trace bisphenol A fromwater samplesrdquo Journal of Hazardous Materials vol 179no 1ndash3 pp 223ndash229 2010

[7] B De Meulenaer K Baert H Lanckriet V Van Hoed andA Huyghebaert ldquoDevelopment of an enzyme-linked im-munosorbent assay for bisphenol A using chicken immu-noglobulinsrdquo Journal of Agricultural and Food Chemistryvol 50 no 19 pp 5273ndash5282 2002

[8] C M A Brett and A M Oliveira-Brett ldquoElectrochemicalsensing in solution-origins applications and future per-spectivesrdquo Journal of Solid State Electrochemistry vol 15no 7-8 pp 1487ndash1494 2011

[9] A amilselvan V Rajagopal and V SuryanarayananldquoHighly sensitive and selective amperometric determinationof BPA on carbon blackf-MWCNT composite modifiedGCErdquo Journal of Alloys and Compounds vol 786 pp 698ndash706 2019

[10] K-J Huang Y-J Liu Y-M Liu and L-L Wang ldquoMolyb-denum disulfide nanoflower-chitosan-Au nanoparticlescomposites based electrochemical sensing platform forbisphenol A determinationrdquo Journal of Hazardous Materialsvol 276 pp 207ndash215 2014

[11] N B Messaoud C Dridi M B Ali and C M A BrettldquoElectrochemical sensor based on multiwalled carbonnanotube andgold nanoparticle modified electrode for thesensitive detection of bisphenol Ardquo Sensors and Actuators Bvol 253 pp 513ndash522 2017

[12] T D Vu P Khac Duy H T Bui S-H Han and H ChungldquoReduced graphene oxide-Nickel sulfide (NiS) composited onmechanical pencil lead as a versatile and cost-effective sensorfor electrochemical measurements of bisphenol A and mer-cury (II)rdquo Sensors and Actuators B Chemical vol 281pp 320ndash325 2019

[13] P Hu X Zhu X Luo X Hu and L Ji ldquoCathodic electro-deposited Cu-BTCMOFs assembled from Cu(II) and trimesicacid for electrochemical determination of bisphenol ArdquoMicrochimica Acta vol 187 p 145 2020

[14] C HouW Tang C Zhang YWang andN Zhu ldquoA novel andsensitive electrochemical sensor for bisphenol A determinationbased on carbon black supporting ferroferric oxide nano-particlesrdquo Electrochimica Acta vol 144 pp 324ndash331 2014

[15] Y Li H Wang B Yan and H Zhang ldquoAn electrochemicalsensor for the determination of bisphenol A using glassycarbon electrode modified with reduced graphene oxide-sil-verpoly-l-lysine nanocompositesrdquo Journal of Electroanalyt-ical Chemistry vol 805 pp 39ndash46 2017

[16] R Shi X Yuan A LiuM Xu and Z Zhao ldquoDetermination ofbisphenol A in beverages by an electrochemical sensor basedon Rh2O3reduced graphene oxide compositesrdquo AppliedSciences vol 8 no 12 p 2535 2018

[17] S U Karabiberoglu ldquoSensitive voltammetric determination ofbisphenol A based on a glassy carbon electrode modified withcopper oxide-zinc oxide decorated on graphene oxiderdquoElectroanalysis vol 30 pp 91ndash102 2018

[18] K Deng X Liu C Li Z Hou and H Huang ldquoA comparativestudy of different Fe3O4-functionalized carbon-based nano-materials for the development of electrochemical sensors forbisphenol Ardquo Analytical Methods vol 9 no 37 p 5509 2017


[19] G Bolat Y T Yaman and S Abaci ldquoHighly sensitive elec-trochemical assay for Bisphenol A detection based on poly(CTAB)MWCNTs modified pencil graphite electrodesrdquoSensors and Actuators B Chemical vol 255 no 1 pp 140ndash148 2018

[20] H Fan Y Li D Wu et al ldquoElectrochemical bisphenol Asensor based on N-doped graphene sheetsrdquo Analytica Chi-mica Acta vol 711 pp 24ndash28 2012

[21] P Jing X Zhang Z Wu et al ldquoElectrochemical sensing ofbisphenol A by graphene-1-butyl-3-methylimidazoliumhexafluorophosphate modified electroderdquo Talanta vol 141pp 41ndash46 2015

[22] Y Lin K Liu C Liu et al ldquoElectrochemical sensing ofbisphenol A based on polyglutamic acidamino-functional-ised carbon nanotubes nanocompositerdquo Electrochimica Actavol 133 pp 492ndash500 2014

[23] R Shi J Liang Z Zhao A Liu and Y Tian ldquoAn electro-chemical bisphenol A sensor based on one step electro-chemical reduction of cuprous oxide wrapped graphene oxidenanoparticles modified electroderdquo Talanta vol 169 pp 37ndash43 2017

[24] B Su H Shao N Li X Chen Z Cai and X Chen ldquoAsensitive bisphenol A voltammetric sensor relying on AuPdnanoparticlesgraphene composites modified glassy carbonelectroderdquo Talanta vol 166 pp 126ndash132 2017

[25] J-Y Wang Y-L Su B-H Wu and S-H Cheng ldquoReusableelectrochemical sensor for bisphenol A based on ionic liquidfunctionalized conducting polymer platformrdquo Talantavol 147 pp 103ndash110 2016

[26] T Yang H Chen R Yang Y Jiang W Li and K Jiao ldquoAglassy carbon electrode modified with a nanocompositeconsisting of molybdenum disulfide intercalated into self-doped polyaniline for the detection of bisphenol Ardquo Micro-chimica Acta vol 182 no 15-16 pp 2623ndash2628 2015

[27] T Zhan Y Song Z Tan and W Hou ldquoElectrochemicalbisphenol A sensor based on exfoliated Ni2Al-layered doublehydroxide nanosheets modified electroderdquo Sensors and Ac-tuators B Chemical vol 238 pp 962ndash971 2017

[28] J Zhang X Xu and L Chen ldquoAn ultrasensitive electro-chemical bisphenol A sensor based on hierarchical Ce-metal-organic framework modified with cetyltrimethylammoniumbromiderdquo Sensors and Actuators B Chemical vol 261 no 15pp 425ndash433 2018

[29] H Yin Y Zhou S Ai R Han T Tang and L Zhu ldquoElec-trochemical behavior of bisphenol A at glassy carbon elec-trode modified with gold nanoparticles silk fibroin andPAMAM dendrimersrdquo Microchimica Acta vol 170 no 1-2pp 99ndash105 2010

[30] Y Gao Y Cao D Yang X Luo Y Tang and H Li ldquoSen-sitivity and selectivity determination of bisphenol A usingSWCNT-CD conjugate modified glassy carbon electroderdquoJournal of Hazardous Materials vol 199-200 pp 111ndash1182012

[31] L Zhang Y-P Wen Y-Y Yao Z-F Wang X-M Duan andJ-K Xu ldquoElectrochemical sensor based on f-SWCNT andcarboxylic group functionalized PEDOT for the sensitivedetermination of bisphenol Ardquo Chinese Chemical Lettersvol 25 no 4 pp 517ndash522 2014

[32] H Li W Wang Q Lv G Xi H Bai and Q Zhang ldquoDis-posable paper-based electrochemical sensor based on stackedgold nanoparticles supported carbon nanotubes for the de-termination of bisphenol Ardquo Electrochemistry Communica-tions vol 68 pp 104ndash107 2016

[33] X Tu L Yan X Luo S Luo and Q Xie ldquoElectroanalysis ofbisphenol A atmultiwalled carbon nanotubes-gold nano-particles modified glassy carbonelectroderdquo Electroanalysisvol 21 pp 2491ndash2494 2009

[34] C Hu and S Hu ldquoElectrochemical characterization ofcetyltrimethyl ammonium bromide modified carbon pasteelectrode and the application in the immobilization of DNArdquoElectrochimica Acta vol 49 no 3 pp 405ndash412 2004

[35] S Hu K Wu H Yi and D Cui ldquoVoltammetric behavior anddetermination of estrogens at nafion-modified glassy carbonelectrode in the presence of cetyltrimethylammonium bro-miderdquo Analytica Chimica Acta vol 464 no 2 pp 209ndash2162002

[36] J Gao and J F Rusling ldquoElectron transfer and electro-chemical catalysis using cobalt-reconstituted myoglobin in asurfactant filmrdquo Journal of Electroanalytical Chemistryvol 449 no 1-2 pp 1ndash4 1998

[37] K D Pham T H Y Pham S Chun T T H Vu andH Chung ldquoCarbon fiber cloth-supported Au nanodendritesas a ruggedsurface-enhanced Raman scattering substrate andelectrochemicalsensing platformrdquo Sensors and Actuators BChemical vol 225 pp 377ndash383 2016

[38] H D Vu T H Y Pham Q G Nguyen et al ldquoCarbon fibercloth-supported Au nanodendrites as a rugged surface-en-hanced Raman scattering substrate and electro-chemicalsensing platformrdquo Electroanalysis vol 30pp 2222ndash2227 2018

[39] Q G Nguyen H D Vu T H Y Pham et al ldquoAu nano-dendrite incorporated graphite pencil lead as a sensitive andsimple electrochemical sensor for simultaneous detection ofPb(II) Cu(II) and Hg(II)rdquo Journal of Applied Electrochem-istry vol 49 pp 839ndash846 2019

[40] E Laviron ldquoAdsorption autoinhibition and autocatalysis inpolarography and in linear potential sweep voltammetryrdquoJournal of Electroanalytical Chemistry and Interfacial Elec-trochemistry vol 52 no 3 pp 355ndash393 1974

[41] S Dong G Suo N Li et al ldquoA simple strategy to fabricatehigh sensitive 24-dichlorophenol electrochemical sensorbased on metal organic framework Cu3(BTC)2rdquo Sensors andActuators B Chemical vol 222 pp 972ndash979 2016

[42] Report of joint FAOWHO expert meeting toxicological andhealth aspects of bisphenol A 2ndash5 November 2010

[43] C Li Y Zhou X Zhu B Ye and M Xu ldquoConstruction of asensitive bisphenol A electrochemical sensor based on metal-organic frameworkgraphene compositesrdquo InternationalJournal of Electrochemical Science vol 13 pp 4855ndash48672018


(MWCNT) plus AuNP modified GCE [11 32 33] becauseAu is the material with extremely high conductivity AsNajib Ben Messaoud et al [11] showed a modified electrodewas prepared by two steps drop-casting a desired amount ofMWCNTon polished GCE followed by deposition of AuNPon the surface of the previously prepared MWCNTGCEWith this sensor the detection limit of BPA reached 4 nMIn this work an electrochemical sensor for BPA detectionconsisting of gold nanodendrites (AuNDs) deposited onGCE which was precovered by cetyltrimethylammoniumbromide (CTAB) CTAB is one of the known cationicsurfactant which has been extensively employed to enhancethe sensitivity of electrochemical sensors [34 35] It is alsopresented that CTAB has a hydrophilic head on one side anda long hydrophobic tail on the other side of its moleculeAlso as reported surfactants adsorbed at the electrodesurface may alter the electrode behavior and accelerate theelectron transfer process between the analyte and theelectrode surface [36] In this context the GCE-supportedAu nanodendrites and CTAB (denoted as AuNDsCTABGCE) were demonstrated as an electrochemical sensorwhich has sensitive electrochemically active surface areasdue to the hierarchical nanodendrites structure and theformation of nanodendrite on the CTABGCE was ac-complished in just 5 minutes by simple one-step electro-deposition e electrochemical behavior of BPA on thissensor was studied by cyclic voltammetry (CV) and elec-trochemical impedance spectroscopy (EIS) and the ana-lytical measurements were performed by differential pulsevoltammetry (DPV) e AuNDsCTABGCE sensor hasbeen employed to detect BPA in aqueous samples andimportant factors related to electrochemical response suchas pH (from 50 to 90) were examined as well to get theoptimal conditions for BPA detection

2 Materials and Methods

21 Materials and Sensor Preparation Bisphenol A (BPA)was purchased from Sigma-Aldrich (Structures inFigure S1) GCE (BAS diameter 3mm) was used as acurrent collector Phosphate buffer solution (PBS) wasprepared by mixing 02M KH2PO4 and 02 MK2HPO4 untilthe desired pH (in the range from 50 to 90) was obtainedPotassium ferrocyanide trihydrate (K4[Fe(CN)6]3H2O)potassium ferricyanide (K3[Fe(CN)6]) and all reagentsneeded for the construction of Au nanodendrites HAuCl4(99999) KI H2SO4 and NH4Cl were bought from Sigma-Aldrich All chemicals were used as received without anyfurther treatments

e AuNDsCTABGCE sensor was prepared as re-ported in our previous publication [37 38] In brief 5 microLCTAB was drop-casted on GCE dried in the atmosphere inabout 2 h 30 to 3 h e dried CTABGCE was put in asolution containing 20mM HAuCl4 1mM KI 5M NH4Cland 05MH2SO4 and previous regime published by authorrsquosgroup was followed [37 38] A current of -20mA was ap-plied to it for the preparation of Au nanodendrites byelectrodeposition for 30 s AuNDsCTABGCE was rinsedthrough by a mixture of EtOH and H2O (1 3) and kept in a

desiccator overnight A scanning electronmicroscope (SEM)image of the built Au nanodendrite was obtained (S-4800Hitachi Japan) with an electron beam accelerated by avoltage of 15ndash20 kV to characterize the structure Fluores-cence spectra were obtained with a FluoroMax-4 spectro-fluorometer equipped with an Ozone-free xenon arc lamp(150W) Czerny-Turner monochromators (HORI-BAndashJapan) All measurements were performed in a 10mmquartz cell at room temperature e emission spectra arerecorded between 470 and 540 nm with the excitationwavelength at 460 nm

22 Electrochemical Measurements of Samples All of theelectrochemical measurements were conducted at roomtemperature (25degCplusmn 1) using a three-electrode system inwhich an AgAgCl electrode and a Pt wire were used as thereference and auxiliary electrode respectively A custom-made multifunctional potentiostat-galvanostat manufac-tured by this research group (Vietnam Academy of Scienceand Technology Hanoi Vietnam) was used It was equippedwith 12-byte analog-digital and digital-analog converterswith two operational amplifiers and it provided the currentresolution down to 0008 nA

DPV was used for BPA measurement with a differentialstep of 0005V a sampling time of 004 s a pulse width of008 s and a pulse amplitude of 005V e accumulationconditions of BPA onto AuNDsCTABGCE were con-ducted at i 0 (under open-circuit potential) with a durationtime of 240 s (selected from previous publications [39] andvoltammograms were recorded over a range of 025 to 085Vversus AgAgCl A PBS solution (pH 7) was used as asupporting electrolyte in all measurements

3 Results and Discussion

31 Surface Morphology of Prepared Sensors e surfacemorphology of AuNDsCTABGCE was examined using theSEM technique (Figure 1) Au nanodendrites were quicklyformed on the electrode surface after 5-minutes of elec-trodeposition When CTAB surfactant was not used theaggregation of gold nanostructures (Figure S2) and theformation of large gold branches (Figure 1(c)) were ob-served e use of CTAB has helped to limit those unwanteddefects thus significantly increased the active surface areaand providedmore access sites for analytes at not only the tipof gold brands but also inside gold branches

32 Electrochemical Performance of AuNDCTABGCEBefore using AuNDsCTABGCE prepared for detection ofBPA on GCE CTABGCE AuNDsGCE and AuNDsCTABGCE electrochemical impedance spectroscopy (EIS)was recorded in 02M PBS containing 5mM Fe(CN)63minus4minusIn the Nyquist diagram (Figure 2) the bare GCE exhibited arelatively low electron transfer resistance (Rct 1463Ω)with a small semicircle (refer to in inset for further detail)After the drop-casting CTAB and deposition of AuNDs theelectron transfer rate dramatically increased which resultedfrom a decrease of the charge transfer resistance (Rct 254O


(a) (b)

(c) (d)


50 100 150 200 250 300 350

0

40

80

120

160

200

GCECTABGCE


0

70

140

210

280

350

420

490

ndashZprime (Ω

)

ndashZprime (Ω

)

100 200 300 400 500 600 700 8000ndashZPrime (Ω)

ndashZPrime (Ω)







Epa Eo

+RTαnF

1113888 1113889lnRTk

o

αnF1113888 1113889 +

RTαnF

1113888 1113889ln(v) (1)






ndash2H+



0

GCECTABGCE



ndash 60

ndash 40

ndash 20

20

40

60

I (μA

)








03 04 05 06 07 08 09 1002E V vs AgAgCl

ndash10

ndash5

0

5

10

15

20

25

I (μA

)

(a)

0 100 200 300 400

y = 003156x + 07415R2 = 099930

2

4

6

8

10

12

I (μA

)

V(mVs)

(b)

2 3 4Inv(mVs)

5 6

y = 00184x + 04949R2 = 09969

EV

vs

Ag

AgC

l

054

056

058

060

062

(c)







0

5

10

15

20

25

30

pH 5pH 6pH 7

pH 8pH 9

I (μA

)

02 03 04 05 06 07 0801E V vs AgAgCl

(a)

0

5

10

15

20

25

30

I (μA

)

5 6 7pH

8 9

(b)

5 6 7pH

8 9

E V

vs

Ag

AgC

l

035

040

045

050

055

060

065

(c)



GCECTABGCE


2 4 6 8 100CBPA (μM )

0

2

4

6

8

10

12

I (μA

)


0μM0025μM005μM

01μM02μM05μM

1μM5μM10μM

04 05 06 07 0803CBPA (μM)

0

2

4

6

8

10

12

14

I (μA

)

02468

1012

I (μA

)

0 2 4 6 8 10 12ndash2CBPA (μM )

(a)

(b)

y = 00012x + 00007R2 = 09996






4 Conclusion





Sample

BPA (microm)









Data Availability




Acknowledgments




References














































(a) (b)

(c) (d)


50 100 150 200 250 300 350

0

40

80

120

160

200

GCECTABGCE


0

70

140

210

280

350

420

490

ndashZprime (Ω

)

ndashZprime (Ω

)

100 200 300 400 500 600 700 8000ndashZPrime (Ω)

ndashZPrime (Ω)







Epa Eo

+RTαnF

1113888 1113889lnRTk

o

αnF1113888 1113889 +

RTαnF

1113888 1113889ln(v) (1)






ndash2H+



0

GCECTABGCE



ndash 60

ndash 40

ndash 20

20

40

60

I (μA

)








03 04 05 06 07 08 09 1002E V vs AgAgCl

ndash10

ndash5

0

5

10

15

20

25

I (μA

)

(a)

0 100 200 300 400

y = 003156x + 07415R2 = 099930

2

4

6

8

10

12

I (μA

)

V(mVs)

(b)

2 3 4Inv(mVs)

5 6

y = 00184x + 04949R2 = 09969

EV

vs

Ag

AgC

l

054

056

058

060

062

(c)







0

5

10

15

20

25

30

pH 5pH 6pH 7

pH 8pH 9

I (μA

)

02 03 04 05 06 07 0801E V vs AgAgCl

(a)

0

5

10

15

20

25

30

I (μA

)

5 6 7pH

8 9

(b)

5 6 7pH

8 9

E V

vs

Ag

AgC

l

035

040

045

050

055

060

065

(c)



GCECTABGCE


2 4 6 8 100CBPA (μM )

0

2

4

6

8

10

12

I (μA

)


0μM0025μM005μM

01μM02μM05μM

1μM5μM10μM

04 05 06 07 0803CBPA (μM)

0

2

4

6

8

10

12

14

I (μA

)

02468

1012

I (μA

)

0 2 4 6 8 10 12ndash2CBPA (μM )

(a)

(b)

y = 00012x + 00007R2 = 09996






4 Conclusion





Sample

BPA (microm)









Data Availability




Acknowledgments




References

















































Epa Eo

+RTαnF

1113888 1113889lnRTk

o

αnF1113888 1113889 +

RTαnF

1113888 1113889ln(v) (1)






ndash2H+



0

GCECTABGCE



ndash 60

ndash 40

ndash 20

20

40

60

I (μA

)








03 04 05 06 07 08 09 1002E V vs AgAgCl

ndash10

ndash5

0

5

10

15

20

25

I (μA

)

(a)

0 100 200 300 400

y = 003156x + 07415R2 = 099930

2

4

6

8

10

12

I (μA

)

V(mVs)

(b)

2 3 4Inv(mVs)

5 6

y = 00184x + 04949R2 = 09969

EV

vs

Ag

AgC

l

054

056

058

060

062

(c)







0

5

10

15

20

25

30

pH 5pH 6pH 7

pH 8pH 9

I (μA

)

02 03 04 05 06 07 0801E V vs AgAgCl

(a)

0

5

10

15

20

25

30

I (μA

)

5 6 7pH

8 9

(b)

5 6 7pH

8 9

E V

vs

Ag

AgC

l

035

040

045

050

055

060

065

(c)



GCECTABGCE


2 4 6 8 100CBPA (μM )

0

2

4

6

8

10

12

I (μA

)


0μM0025μM005μM

01μM02μM05μM

1μM5μM10μM

04 05 06 07 0803CBPA (μM)

0

2

4

6

8

10

12

14

I (μA

)

02468

1012

I (μA

)

0 2 4 6 8 10 12ndash2CBPA (μM )

(a)

(b)

y = 00012x + 00007R2 = 09996






4 Conclusion





Sample

BPA (microm)









Data Availability




Acknowledgments




References



















































03 04 05 06 07 08 09 1002E V vs AgAgCl

ndash10

ndash5

0

5

10

15

20

25

I (μA

)

(a)

0 100 200 300 400

y = 003156x + 07415R2 = 099930

2

4

6

8

10

12

I (μA

)

V(mVs)

(b)

2 3 4Inv(mVs)

5 6

y = 00184x + 04949R2 = 09969

EV

vs

Ag

AgC

l

054

056

058

060

062

(c)







0

5

10

15

20

25

30

pH 5pH 6pH 7

pH 8pH 9

I (μA

)

02 03 04 05 06 07 0801E V vs AgAgCl

(a)

0

5

10

15

20

25

30

I (μA

)

5 6 7pH

8 9

(b)

5 6 7pH

8 9

E V

vs

Ag

AgC

l

035

040

045

050

055

060

065

(c)



GCECTABGCE


2 4 6 8 100CBPA (μM )

0

2

4

6

8

10

12

I (μA

)


0μM0025μM005μM

01μM02μM05μM

1μM5μM10μM

04 05 06 07 0803CBPA (μM)

0

2

4

6

8

10

12

14

I (μA

)

02468

1012

I (μA

)

0 2 4 6 8 10 12ndash2CBPA (μM )

(a)

(b)

y = 00012x + 00007R2 = 09996






4 Conclusion





Sample

BPA (microm)









Data Availability




Acknowledgments




References


















































0

5

10

15

20

25

30

pH 5pH 6pH 7

pH 8pH 9

I (μA

)

02 03 04 05 06 07 0801E V vs AgAgCl

(a)

0

5

10

15

20

25

30

I (μA

)

5 6 7pH

8 9

(b)

5 6 7pH

8 9

E V

vs

Ag

AgC

l

035

040

045

050

055

060

065

(c)



GCECTABGCE


2 4 6 8 100CBPA (μM )

0

2

4

6

8

10

12

I (μA

)


0μM0025μM005μM

01μM02μM05μM

1μM5μM10μM

04 05 06 07 0803CBPA (μM)

0

2

4

6

8

10

12

14

I (μA

)

02468

1012

I (μA

)

0 2 4 6 8 10 12ndash2CBPA (μM )

(a)

(b)

y = 00012x + 00007R2 = 09996






4 Conclusion





Sample

BPA (microm)









Data Availability




Acknowledgments




References














































GCECTABGCE


2 4 6 8 100CBPA (μM )

0

2

4

6

8

10

12

I (μA

)


0μM0025μM005μM

01μM02μM05μM

1μM5μM10μM

04 05 06 07 0803CBPA (μM)

0

2

4

6

8

10

12

14

I (μA

)

02468

1012

I (μA

)

0 2 4 6 8 10 12ndash2CBPA (μM )

(a)

(b)

y = 00012x + 00007R2 = 09996






4 Conclusion





Sample

BPA (microm)









Data Availability




Acknowledgments




References

















































4 Conclusion





Sample

BPA (microm)









Data Availability




Acknowledgments




References















































Data Availability




Acknowledgments




References














































AnElectrochemicalSensorBasedonGold Nanodendrite ...3.7. Reproducibility, Repeatability, and...

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Transcript of AnElectrochemicalSensorBasedonGold Nanodendrite ...3.7. Reproducibility, Repeatability, and...