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Synthesis of (Hexaconazole-Zinc/Aluminium-Layered Double Hydroxide Nanocomposite) Fungicide Nanodelivery System for Controlling Ganoderma Disease in Oil Palm Isshadiba Mustafa, Mohd Zobir Hussein, Bullo Saifullah, Abu Seman Idris, Nur Hailini Zainol Hilmi, and Sharida Fakurazi J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.7b04222 • Publication Date (Web): 28 Dec 2017 Downloaded from http://pubs.acs.org on December 29, 2017

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Journal of Agricultural and Food Chemistry

1

Synthesis of (Hexaconazole-Zinc/Aluminium-Layered Double Hydroxide Nanocomposite)

2

Fungicide Nanodelivery System for Controlling Ganoderma Disease in Oil Palm

3 4

Isshadiba F. Mustafa1, Mohd Zobir Hussein1*, Bullo Saifullah1, Abu Seman Idris2, Nur

5

Hailini Z. Hilmi2 and Sharida Fakurazi3,4

6 1

7 8

Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia 2

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Malaysian Palm Oil Board (MPOB), No.6, Persiaran Institusi, Bandar Baru Bangi, 43000,

10

Kajang, Selangor, Malaysia 3

11 12 13

Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology,

Laboratory of Vaccine and Immunotherapeutics, Institute of Bioscience (IBS), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

4

Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra

14

Malaysia, 43400 UPM Serdang, Selangor, Malaysia

15

Corresponding author: [email protected]

16 17 18 19 20 21 22 23 24 25

ACS Paragon Plus Environment


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Abstract: Fungicide, namely hexaconazole was successfully intercalated into the

27

intergalleries of zinc/aluminium-layered double hydroxide (ZALDH) using ion exchange

28

method. Due to the intercalation of hexaconazole, the basal spacing of the ZALDH was

29

increased from 8.7 Å in ZALDH to 29.45 Ǻ in hexaconazole-intercalated ZALDH

30

(HZALDH). The intercalation of hexaconazole into the interlayer of the nanocomposite was

31

confirmed using the Fourier-transform infrared (FTIR) study. This supramolecular chemistry

32

intercalation process enhanced the thermal stability of the hexaconazole moiety. The

33

fungicide loading was estimated to be 51.8 %. The nanodelivery system also shows better

34

inhibition towards the Ganoderma boninense growth than the counterpart, free hexaconazole.

35

The results from this work have a great potential to be further explored for combating basal

36

stem rot (BSR) disease in oil palm plantation.

37 38

Keywords: Nanocomposite, layered double hydroxide, hexaconazole, nanodelivery,

39

agronanochemical.

40 41 42 43 44 45 46 47 48 49


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1. Introduction

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Ganoderma boninense is a wood-rotting fungus that has caused basal stem rot (BSR)

53

disease in oil palm. This disease is one of the critical issue causing low yields in the oil palm

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industry in Malaysia.

55

In controlling the BSR disease, the fungicides such as hexaconazole and dazomet were

56

used. However, it was reported that the use of the fungicides had increased soil acidity since

57

the residue of hexaconazole fungicide in the soil sample was found to be at the double

58

recommended dosage1. There is currently no effective way to ensure that the fungicides was

59

only released at the fungal site instead of going downward in soil profile through leaching. In

60

this work, a fungicide controlled release formulation was designed and synthesized in

61

controlling the release of fungicides and subsequently reduce the acidity problem.

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Lately, many researchers were attracted on layered double hydroxides or also called

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hydrotalcite-like compounds. LDHs are a group of inorganic nanolayers with structurally

64

positively charged layers and interlayer balancing anions. This inorganic nanolayer also

65

known as anionic clay, with formula (MII

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referring to divalent while MIII is trivalent cations and An- represents the anions which are able

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to balance the electro-neutrality of the positive charged layers2. The superior properties of

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LDH such as its biocompatibility, its ability to act as removal agents of pesticides, slow

69

release system and low toxicity makes it suitable to be used for various agriculture

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applications 3.

1-x

MIII

x

[OH]2 ).(Ax/nn-).yH2O in which MII is

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It was reported that hexaconazole was intercalated into Mg/Al-LDH exhibited a

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potential pesticide controlled release4, but currently, no study on antifungal potential towards

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Ganoderma boninense by using Zn/Al LDH as a carrier. In this work, hexaconazole was

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accommodated in intergalleries of Zn/Al-LDH (ZALDH) so that the release of fungicide can



75

be occurred in a sustained manner. The use of Zn/Al-LDH is hoped to have beneficial effect

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as Zn is an essential element for plant.

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Here we discuss our work on the intercalation of hexaconazole into the interlamellae of

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ZALDH to form a nanocomposite of hexaconazole-ZALDH 2D layered structure and

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subsequently study its physico-chemical and phytotoxicity properties. Hexaconazole was

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selected in this work because it is widely introduced as a preventive treatment and prolonging

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the productive life of infected palms5.

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2. Materials and methods

83 84

2.1 Materials

85 86

Hexaconazole, with 95 % pure (Changzhou, China) was used as received. All chemical

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reagents involved were obtained from Sigma-Aldrich. All experiments were conducted using

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deionized water.

89 90

2.2 Method

91 92

2.2.1

Synthesis of Zn/Al-NO3-LDH

93 94

The salts of Zn(NO3)2 and Al(NO3)3 were dissolved in 250 mL deionised water with a

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molar ratio of 2:1. After 15 minutes, the NaOH solution with concentration of 2 M, was

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dropped slowly to the mixture until the solution was achieved to pH 7-7.5 with vigorous

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stirring under nitrogen environment. Then, the sample was kept into an oil bath at 70 °C for

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18 h, washed three times with deionised water and centrifuged 6. After drying in an oven for


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two days, the sample obtained was labeled as ZALDH.

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2.2.2 Synthesis of hexaconazole micelle

102 103

An amount of 1.223 g of anionic surfactant, sodium dodecylbenzenesulfonate was

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dispersed into 250 mL deionised water, 100 mL acetone solution containing 0.2 mol

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fungicide, hexaconazole was mixed with the surfactant and stirred at 40-45 °C. The fungicide

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micelle was obtained once the acetone was fully evaporated 7.

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2.2.3 Synthesis of Zn/Al-hexaconazole by the ion-exchanged method

109 110

About 0.5 g ZALDH was added into a 250 mL solution containing approximately 150

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mL, 0.2 M hexaconazole micelle. Then, the mixture was stirred at 75 ºC for 72 h. After that,

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the sample was obtained after centrifugation process using deionised water and acetone. The

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fungicide-LDHs, labeled as HZALDH nanocomposite was obtained after drying at 70 ºC in an

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oven for about 72 h.

115 116

2.3

Characterizations

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Powder X-ray diffraction (PXRD) pattern was recorded using a Shidmadzu

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diffractometer, with 2-60° in range, by a CuKα radiation source (λ=1.5405 Å) driven at 40 kV

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and 30 mA. The FTIR spectra were obtained using a Perkin-Elmer 1725X spectrophotometer

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by ATR technique with wavelength of 400-4000 cm-1. Thermogravimetric analyses (TGA)

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was carried out using a Mettler Toledo instrument with 50 mL/min nitrogen flow and 10



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⁰C/min heating rate, between 25-1000 ⁰C. The surface morphology of the nanocomposite was

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studied using a scanning electron microscope (SEM), JEOL JSM – 6400 model. A Perkin

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Elmer ultraviolet-visible spectrophotometer (Lambda 35) was used in determination of

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controlled release property. The high-performance liquid chromatography (HPLC), equipped

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with Sykam S3250 UV/Vis detector was used to determine the percentage of the

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hexaconazole loading.

129 130

2.4

Measurements of release amount of hexaconazole from HZALDH

131 132

The release of fungicide from HZALDH nanocomposite was conducted in a pH 5.5

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(soil pH) of phosphate-buffered solution. HZALDH nanocomposite (10 mg) was put into 20

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mL phosphate buffer solution. At preset interval times, the sample was taken (2-3 mL) and

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replaced with new solution. After the aliquot was filtered, the fungicide content was

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determined at the maximum wavelength of 202 nm using an ultraviolet-visible

137

spectrophotometer.

138 139

2.5

Loading amount of hexaconazole in HZALDH

140 141

HPLC analysis of the hexaconazole fungicide in the HZALDH nanocomposite was

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carried out using the method as previously described elsewhere8. Two mobile phases were

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used, namely acetonitrile and 0.1 % orthophosphoric acid. The isocratic mobile phase of

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acetonitrile and orthophosphoric acid was fixed at a ratio of 75:25, with a flow rate of 1

145

mL/min. It was shown that the retention time was 2.9 minutes. A calibration curve was

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obtained by running a standard at different concentrations of hexaconazole (0, 50, 100, 150,

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and 200 ppm), resulted in a good R2 value of 0.98. Approximately, 10 mg of the HZALDH


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was dissolved in 50 mL (5 mL of 1 molar HCl and the remaining volume was composed of

149

the mobile phase) and standard hexaconazole solutions were also prepared in the same way.

150

The percentage loading of hexaconazole in HZALDH nanocomposite was calculated to be

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51.8 %.

152 153

2.6

Assessment of antifungal activity

154 155

2.6.1 Culture of Ganoderma boninense

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Pathogenic G. boninense culture (PER71) was obtained from the Malaysian Palm Oil

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Board (MPOB), Bangi, Malaysia. The culture was maintained in Petri dishes (diameter 10

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mm) on potato dextose agar (PDA) media (Oxoid, Thermo Scientific) (pH 5.5) and incubated

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at 28 ± 2 °C prior to further usage.

161 162

2.6.2 Determination of antifungal activity of the nanocomposites against G. boninense

163 164

The antifungal activity of the nanocomposites was tested for their antibiosis properties

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through poison food agar assay. Mycelial discs (5 mm) of 7 days old fungal culture were sub-

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cultured in the middle of PDA agar plates containing different concentrations of

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nanocomposites. The PDA has been previously prepared by incorporating the desired

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concentration of fungicide, i.e. 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1.0, 5.0 and 10.0 ppm into

169

sterilized PDA. The inoculated plates were sealed and incubated at 28 ± 2 °C for 7 days.

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The growth of G. boninense in the agar plate was measured through the radius growth

171

and the measurements were taken throughout the 7 days. Using the Equation 19, the

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percentage inhibition of radical growth (PIRG) was calculated;



PIRG = (R1 – R2) / R1 x 100

173

(1)

174

where R1 is the radius growth of G. boninense in a control plate and R2 is the radius growth of

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G. boninense in the fungicides treated plate.

176 177

2.6.3 Statistical analysis

178 179

All data are presented as mean ± standard deviation for 5 independent tests. The

180

comparison of values obtained was analyzed using a Minitab 16 statistical analysis software

181

(Minitab Inc., State College, PA, USA) by one way and two way analysis of variance

182

(ANOVA) followed by the Tukey’s test. The significant value was considered when p-value

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is less than 0.05.

184

3.

Results and Discussion

185 186

3.1 Powder x ray diffraction analysis

187 188

The XRD patterns of HZALDH nanocomposite, prepared using ion exchange method

189

was shown in Figure 1(A). Based on the figure, pure ZALDH has a basal spacing of 8.7 Ǻ,

190

consistent with a monolayer of nitrate as the counter anion. This is because the brucite-like

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layer has a thickness of 4.8 Ǻ and the remaining 3.9 Ǻ corresponds to a monolayer of the the

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nitrate anion 10. The resulting nanocomposite has expanded from 8.7 to 28.9 Ǻ, which indicate

193

that the newly exchanged anion, hexaconazole has been intercalated into the intergalleries of

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ZALDH to replace nitrate. It was obviously seen that the hexaconazole has higher affinity to

195

be intercalated into the LDH intergalleries compared to the nitrate, due to its higher

196

concentration or bigger size11.


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The results showed that the preparation using 0.2 M HZALDH displayed a sharp,

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symmetric, high crystallinity, showing the pure product has been obtained with no left over

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adsorbed Zn(NO3)2 and Al2(NO3)3. After several optimisations using various concentrations

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of hexaconazole micelle, this sample was then chosen for further studies. A slow scan PXRD

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of the sample, HZALDH exhibits 8 harmonics; 29.45, 14.83, 9.65, 7.30, 5.84, 4.96, 4.25, and

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3.67 Ǻ as shown in Figure 1D, which producing an average basal spacing of 29.42 Ǻ. This

203

value was determined by dividing sum of reflections (nxd) with the total number of

204

reflections. This value was then used to predict the plausible arrangement of hexaconazole in

205

the intergallery of HZALDH nanocomposite.

206 207

3.2 Spatial orientation of the hexaconazole moiety in the ZALDH interlayers.

208 209

Figure 2 (A) and (B) show the three dimensional molecular size of hexaconazole and

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sodium dodecylbenzesulfonate (SDBS) using a Chemoffice software. The x, y and z axes of

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hexaconazole and SDBS were calculated and were found to be 10 Å, 8 Å, 5 Å and 24 Å, 6 Å,

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4 Å, respectively. Based on the XRD pattern, HZALDH nanocomposite synthesized at 0.2 M

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hexaconazole has a mean of basal spacing (d) with value of 29.42 Å. Therefore by subtracting

214

the layer thickness of the ZALDH layer which is 4.8 Å, a value of 24.62 Å was obtained.

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Therefore, 24.62 Å is a space that can be allocated for the spatial orientation of hexaconazole

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molecule in the interlayer of ZALDH. The plausible arrangement of hexaconazole is found

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to be oriented in a biomolecular vertical form along with sodium dodecylbenzene sulfonate

218

and water molecules, as shown in Figure 2 (C)12.

219 220

3.3 Fourier-transform infrared analysis

221



222

The presence of hexaconazole moiety in the ZALDH nanolayers has been confirmed

223

by the FTIR spectroscopy (see Fig. 3). The hydroxyl group of the LDH layers and the nitrate

224

anion stretching vibration can be seen at 3440 and 1378 cm-1 as shown in infrared spectrum of

225

ZALDH (Fig. 3B). The 1638 cm-1 band was due to H-OH bending vibration. Fig. 3A shows

226

that the hexaconazole displays a band at 3217 cm-1, which represents hydroxyl group

227

vibrational mode. The C=C and C-H stretching from the aromatic ring were detected at 1431

228

and 847 cm-1. FTIR spectra of HZALDH nanocomposite (Fig. 3C) shows the characteristic

229

bands of hexaconazole alone with slightly shift in the wavenumber position, which indicates

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the incorporation of hexaconazole into the ZALDH intergalleries.

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After the intercalation of hexaconazole, the 1601 cm-1 band has been formed, which

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indicates that C=N stretching from hexaconazole molecule has present. The band assigned to

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the nitrate anions (1378 cm-1) was absent in this resulting nanocomposite, which strongly

234

support that the NO3- anions have been replaced by the fungicide moiety, hexaconazole. The

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existence of hexaconazole in the new nanodelivery system and sulfonate ions can be observed

236

at 2956 and 687 cm-1 13.

237 238

3.4 Thermal Studies

239 240

Fig. 4 illustrates the TGA/DTG thermograms of free hexaconazole, ZALDH and

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HZALDH nanocomposite. . For hexaconazole, the thermogram (Fig. 4A) shows a sharp peak

242

at 283 °C with 100 % weight loss, due to complete combustion of hexaconazole moiety. In

243

Fig.4B, ZALDH shows four stages of weight loss, observed at 108, 244, 310 and 510 °C, with

244

percentage loss of 7.0, 16.7, 4.0 and 5.5 %, respectively. The first one was associated with

245

loss of water molecule. The second one is due to strongly held water molecules and the third

246

and fourth weight losses are almost completed at 510 °C, which referring to dehydroxylation


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of brucite-like layers and removal of the interlayer anions14.

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Due to the intercalation of hexaconazole into the interlayer of ZALDH (Fig. 4C),

249

TGA/DTG curves show five thermal events at 90, 229, 322, 425 and 888 °C with weight

250

losses of 6.9, 8.3, 10.9, 30.3 and 6.9 %, respectively. The first and the second stage of weight

251

losses are the same as that for ZALDH, which is due to the removal of adsorbed water and

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dehydroxylation of the hydroxyl layer, respectively. The third stage at 322 °C is a result of the

253

organic moiety decomposition in the interlayer of the nanohybrid, leaving only a relatively

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less volatile metal oxide15. The weight loss was increased to 30.3 % at 425 °C in HZALDH

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nanocomposite because of the hexaconazole anions combustion. The last stage of weight loss

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that occurred at around 888 °C was due to the formation of the spinel (ZnAl2O4) phase16. This

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was presumably due to the high electrostatic force in the molecule as the thermal

258

decomposition affected by the substituents on the ligand17.

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It was obviously seen that the thermal stability of HZALDH nanocomposite was

260

greatly increased after the intercalation which is at 425 °C compared to 283 °C (for the free

261

hexaconazole). The result had shown that ZALDH has a potential to be used as a carrier to

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store fungicide with good thermal stability.

263 264

3.5 Surface morphology

265 266

Figs. 5 (A) and (B) show the field emission scanning electron micrograph, showing

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the surface morphology of HZALDH at 50,000x and 100,000x magnifications, respectively.

268

The HZALDH nanocomposite shows agglomerated non uniform granule structure, similar to

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the other nanocomposites previously prepared by other works18.

270 271

3.6 Release behavior of hexaconazole from HZALDH nanocomposite



272 273

The release behaviors of both pure hexaconazole and HZALDH nanocomposite

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were studied in PBS solution at pH 5.5 as shown in Fig. 6. The release behavior of pure

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hexaconazole was very fast for the first 420 min, and become slower thereafter, before it

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achieved 100 % complete release in 2000 min. The rapid release of the hexaconazole from the

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nanocomposite was observed initially, then followed with a slower one thereafter and finally

278

the sustained release was achieved at 62 % after 3000 min. It is obviously seen that the

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hexaconazole released from the nanocomposite was slower than the release of free

280

hexaconazole. This indicates that the nanocomposite served a role as a fungicide controlled

281

release system. The electrostatic interaction between the positively charged ZALDH

282

nanolayers and the negatively charged hexaconazole anions have influences the release

283

property of hexaconazole from its HZALDH interlayers.

284 285

3.7 Release kinetics of hexaconazole from the nanocomposite

286 287

The release kinetics of the hexaconazole from HZALDH nanocomposite was

288

analyzed using the pseudo-first order Eq. (2)19, pseudo-second order Eq. (3)20, Hixon-Crowell

289

Eq. (4)21, Higuchi Eq. (5)22, and Korsmeyer Peppas model Eq. (6)23. The equations are given

290

below;

291 292

ln (qe-qt) = ln qe-kt

(2)

293

t/qt = 1/kqe2 + t/qe

(3)

294

qo 1/3 – qt 1/3 = kt

(4)

295

qt = k(t)0.5

(5)

296

qt = ktn

(6)


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297 298

where qo, qe and qt are the initial amount of anions, equilibrium release amount and release

299

amount at time t, respectively with k is the corresponding release rate constant.

300

Fig. 7 displays the five kinetic models used to fit the release data of hexaconazole from

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nanocomposite. The parameters such as the rate constant, k and the correlation coefficient

302

value, R2 obtained from the five models are shown in Table 2. As shown in results above, the

303

best fitted of the release of hexaconazole from the pure phase, ZALDH inorganic host is the

304

pseudo-second order kinetic model.

305 306

3.8 Antifungal activity of the nanocomposite against the G. boninense

307 308

The antifungal activity of free hexaconazole, ZALDH and HZALDH sample of different

309

concentrations (0.001 to 10 ppm) towards G. Boninense were tested and are represented in

310

Fig. 8 (A to D) with the error bar as standard deviation. The inhibition zone of G. boninense

311

by the samples are also illustrated in Fig. 8 (E). (Based on Fig. 8(A) and 8(C), it can be seen

312

that the HZALDH is fully inhibited the G. boninense growth at lower concentration, 0.1 ppm,

313

compared to hexaconazole alone, which is at 0.5 ppm. On the other hand, for the ZALDH

314

(Fig. 8B), the radial growth of G. boninense steadily increased to the seventh days, which

315

shows that it gives no effect on inhibition towards the G. boninense growth. This study also

316

revealed that the as-synthesized nanocomposite exhibited significant anti-fungal activity as

317

shown in Fig. 8(D).

318

As a result of using probit analysis of Sigma Plot 10.0, the half maximal effective

319

concentration, EC50 was obtained. The value of EC50 for hexaconazole, ZALDH and

320

HZALDH was found to be 0.05, 2.03 and 0.03 ppm, respectively. These findings indicate that

321

the resulting nanodelivery system of hexaconazole developed in this work is more effective in



322

combating G. boninense compared to its counterpart, the free hexaconazole as indicated by

323

the lower EC50 value, 0.03 compared to 0.05 ppm, respectively.

324

Table 3 and Table 4 represent the significant effects of pure hexaconazole, ZALDH,

325

HZALDH concentrations under one – way ANOVA and the interaction between the treatment

326

and concentration towards the growth of Ganoderma boninense under two-way ANOVA,

327

respectively. The mean and standard deviation of different concentrations of pure

328

hexaconazole and HZALDH are significant, while for the ZALDH, it is insignificant to

329

growth as shown in Table 3. In comparing both factors of treatment and concentration, the

330

treatment give highly significant effect towards the growth, about seven times compared to

331

concentration, as shown in Table 4.

332

This finding has showed that zinc/aluminium layered double hydroxide can be used

333

as a nanocarrier for a fungicide, hexaconazole in developing new environmental-friendly

334

agronanochemicals.

335

Acknowledgement

336 337

This project was supported by the Universiti Putra Malaysia and the Ministry of Higher

338

Education of Malaysia (UPM-MOHE) grants under the NANOMITE vot no. 9443100 and

339

5526300. The G. boninense studies were accomplished at the Malaysian Palm Oil Board

340

(MPOB) laboratory and facilities.

341

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formulation of an herbicide, 2,4-dichlorophenoxyacetate incapsulated in zinc –

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Page 18 of 30

Page 19 of 30


Fig. 1. PXRD patterns of free hexaconazole (A), ZALDH (B) and HZALDH nanocomposite (C) and the slow scan with a dwell time of 0.5°/min (D) and from the 8 reflections, the average value of the interlamellae (nxd) was found to be 29.42 Å.



Page 20 of 30

C

A

B

Carbon

Nitrogen

Sulphur

Chlorine

Hydrogen

Oxygen

Fig. 2. Three–dimensional structure of hexaconazole (A), sodium dodecylbenzenesulfonate (B) and plausible arrangement of hexaconazole and sodium dodecylbenzenesulfonate in the intergallery of HZALDH nanocomposite (C)


Page 21 of 30


Fig. 3. Fourier transformed infrared (FTIR) spectra of free hexaconazole (A), ZALDH (B) and HZALDH (C).



A

a

B B

C

Fig. 4. TGA/DTG thermograms of hexaconazole (A), ZALDH (B) and HZALDH nanocomposite (C).


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Page 23 of 30


A

B

Fig. 5. Field emission scanning electron micrographs of HZALDH nanocomposites (A and B) at 50,000x and 100,000x magnifications.



Page 24 of 30

Table 1. The thermal properties of pure hexaconazole, ZALDH and HZALDH nanocomposite.

Sample name

T1-T2

Ts (⁰C )

∆m (mg)

Weight loss (%)

Pure hexaconazole

160-328

283

8.34

100

34-160

108

0.40

7.0

160-285

244

1.57

16.7

285-355

310

0.33

4.0

355-560

510

0.45

5.5

30-146

90

0.58

6.9

146-265

229

0.77

8.3

265-361

322

1.07

10.9

361-587

425

3.08

30.3

778-994

888

0.41

6.9

ZALDH

HZALDH


Page 25 of 30


Fig. 6. Release profiles of hexaconazole from pure hexaconazole and HZALDH nanocomposite at pH 5.5.



Fig. 7. Fitting the release data of hexaconazole from nanocomposite using the pseudo-first order, pseudo-second order kinetics, Higuchi, Hixon-Crowell and Korsmeyer Peppas models.


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Page 27 of 30


Table 2. Rate constant and correlation coefficient (R2) value of the release data of hexaconazole from the nanocomposite using pseudo-first order, pseudo-second order, Higuchi model, Hixon-Crowell and Korsmeyer Peppas kinetic models.

Sample

HZALDH

C

Saturation release (%) 62

R2 Pseudofirst order 0.9166

Korsmeyer -Peppas model 0.8101

Pseudo-second order Higuchi model 0.8743

HixonCrowell model 0.7227

D


R2

0.9975

Rate constant, k (mg/min) 1.54x10-2


Page 28 of 30

E

I

II

III

IV

Fig. 8. The growth curves of G. Boninense treated with hexaconazole (A), ZALDH (B), HZALDH (C) for seven days and the percentage of inhibition radical growth (PIRG) against concentration (ppm) of free hexaconazole, HZALDH and the control after 7 days (D) where *p >0.05 and **p

Aluminum ... - ACS Publications

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