Aluminum ... - ACS Publications

Dec 28, 2017 - Isshadiba F. Mustafa† , Mohd Zobir Hussein†, Bullo Saifullah†, Abu Seman Idris‡, Nur Hailini Z. Hilmi‡, and Sharida FakuraziÂ...
0 downloads 0 Views 2MB Size
Subscriber access provided by the University of Exeter

Article

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

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Journal of Agricultural and Food Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 30

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

9

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

Journal of Agricultural and Food Chemistry

26

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

ACS Paragon Plus Environment

Page 2 of 30

Page 3 of 30

Journal of Agricultural and Food Chemistry

50

1. Introduction

51 52

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

54

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.

62

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

63

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

66

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

67

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

68

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

70

applications 3.

1-x

MIII

x

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

71

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

72

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

73

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

74

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

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

75

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

76

as Zn is an essential element for plant.

77

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

78

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

79

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

80

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

81

the productive life of infected palms5.

82

2. Materials and methods

83 84

2.1 Materials

85 86

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

87

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

88

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

95

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

96

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

97

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

98

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

ACS Paragon Plus Environment

Page 4 of 30

Page 5 of 30

Journal of Agricultural and Food Chemistry

99

two days, the sample obtained was labeled as ZALDH.

100 101

2.2.2 Synthesis of hexaconazole micelle

102 103

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

104

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

105

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

106

micelle was obtained once the acetone was fully evaporated 7.

107 108

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

111

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

112

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

113

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

114

oven for about 72 h.

115 116

2.3

Characterizations

117 118

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

119

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

120

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

121

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

122

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

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

123

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

124

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

125

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

126

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

127

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

128

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

133

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

134

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

135

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

136

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

142

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

143

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

144

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

146

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

147

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

ACS Paragon Plus Environment

Page 6 of 30

Page 7 of 30

Journal of Agricultural and Food Chemistry

148

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

151

51.8 %.

152 153

2.6

Assessment of antifungal activity

154 155

2.6.1 Culture of Ganoderma boninense

156 157

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

158

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

159

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

160

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

165

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

166

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

167

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

168

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.

170

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

172

percentage inhibition of radical growth (PIRG) was calculated;

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

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

175

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

183

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

191

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

192

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

194

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.

ACS Paragon Plus Environment

Page 8 of 30

Page 9 of 30

Journal of Agricultural and Food Chemistry

197

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

198

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

199

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

200

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

201

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

202

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

210

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

211

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

212

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

213

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.

215

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

216

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

217

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

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

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

230

the incorporation of hexaconazole into the ZALDH intergalleries.

231

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

232

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

233

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

235

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

241

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

ACS Paragon Plus Environment

Page 10 of 30

Page 11 of 30

247

Journal of Agricultural and Food Chemistry

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

248

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

252

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

254

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

255

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

256

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

257

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

258

decomposition affected by the substituents on the ligand17.

259

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

262

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

267

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

269

the other nanocomposites previously prepared by other works18.

270 271

3.6 Release behavior of hexaconazole from HZALDH nanocomposite

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

272 273

The release behaviors of both pure hexaconazole and HZALDH nanocomposite

274

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

275

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

276

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

277

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

279

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)

ACS Paragon Plus Environment

Page 12 of 30

Page 13 of 30

Journal of Agricultural and Food Chemistry

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

301

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

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

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

References

342

1.

343

344

Maznah Z, Halimah M, Ismail S, Idris AS. Dissipation of the fungicide hexaconazole in oil palm plantation. Environ Sci Pollut Res Int. August 2015.

2.

Touloupakis E, Margelou A, Ghanotakis DF. Intercalation of the herbicide atrazine in

ACS Paragon Plus Environment

Page 14 of 30

Page 15 of 30

Journal of Agricultural and Food Chemistry

345

layered double hydroxides for controlled-release applications. Pest Manag Sci. 2011,

346

67, 837-841.

347

3.

348

349

Morais R, Aquino LA De. Revisão De Literatura Layered Double Hydroxides : Nanomaterials for Applications in Agriculture. 2011, 1,1-13.

4.

Zhenlan Q, Heng Y, Bin Z, Wanguo H. Synthesis and release behavior of bactericides

350

intercalated Mg-Al layered double hydroxides. Colloids Surfaces A Physicochem Eng

351

Asp. 2009, 348,164-169.

352

5.

Idris, A S And Maizatul Sm. Prolonging The Productive Life Of Ganoderma-Infected

353

Oil Palm With Dazomet, Mpob Information Series No. 616, Mpob Ts No. 108. 2pp.

354

2012, 2-4.

355

6.

Saifullah B, Hussein MZ, Hussein-Al-Ali SH, Arulselvan P, Fakurazi S.

356

Antituberculosis nanodelivery system with controlled-release properties based on para-

357

amino salicylate-zinc aluminum-layered double-hydroxide nanocomposites. Drug

358

Design , Development and Therapy. 2013, 7, 1365-1375.

359

7.

360

361

camptothecin. 2004, 95, 501-514.

8.

362

363

Tyner KM, Schiffman SR, Giannelis EP. Nanobiohybrids as delivery vehicles for

Extraction S. Simultaneous Extraction and Detection of Six Fungicide Residues in Mango Fruit Followed by New Validated HPLC-UV Method. 2013, 1, 80-84.

9.

Skidmore Bam, Dickinson Ch. Colony Interactions And Hyphal Interference Between

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

364

365

Septoria Nodorum And Phylloplane Fungi. Trans Br Mycol Soc. 1976, 66, 57-64.

10.

366

367

Touloupakis E, Margelou A, Ghanotakis DF. Intercalation of the herbicide atrazine in layered double hydroxides for controlled-release applications. 2011, 837-841.

11.

Sheikh Mohd Ghazali SAI, Hussein MZ, Sarijo SH. 3,4-Dichlorophenoxyacetate

368

interleaved into anionic clay for controlled release formulation of a new

369

environmentally friendly agrochemical. Nanoscale Res Lett. 2013, 8, 362.

370

12.

Saifullah B, Arulselvan P. Development of a highly biocompatible antituberculosis

371

nanodelivery formulation based on para-aminosalicylic acid—zinc layered hydroxide

372

nanocomposites. Sci World Journal. 2014.

373

13.

374

375

Xu ZP, Braterman PS. High affinity of dodecylbenzene sulfonate for layered double hydroxide and resulting morphological changes. J Mater Chem. 2002, 13(2), 268-273.

14.

Barahuie F, Hussein MZ, Gani SA, Fakurazi S, Zainal Z. Synthesis of protocatechuic

376

acid-zinc/aluminium-layered double hydroxide nanocomposite as an anticancer

377

nanodelivery system. J Solid State Chem. 2015, 221, 21-31.

378

15.

Hussein MZ, Hashim N, Yahaya AH, Zainal Z. Synthesis of Dichlorprop-Zn/Al-

379

hydrotalcite Nanohybrid and its Controlled Release Property. Sains Malaysiana. 2011,

380

40(8), 887-896.

381 382

16.

Cheng X, Huang X, Wang X, Sun D. Influence of calcination on the adsorptive removal of phosphate by Zn – Al layered double hydroxides from excess sludge liquor.

ACS Paragon Plus Environment

Page 16 of 30

Page 17 of 30

Journal of Agricultural and Food Chemistry

383

384

J Hazard Mater. 2010, 177(1-3), 516-523.

17.

385

386

Lalia-Kantouri M. Factors Influencing The Thermal Decomposition Of Transition Metal Complexes With 2-Oh-Aryloximes Under Nitrogen. 2005, 82, 791-796.

18.

Zobir M, Yahaya AH, Zainal Z, et al. Nanocomposite-based controlled release

387

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

388

aluminium-layered

389

formulation of an herbicide. 2005, 6996.

390

19.

double

hydroxide

Nanocomposite-based

controlled

release

Dong L, Li Y, Hou W, Liu S. Journal of Solid State Chemistry Synthesis and release

391

behavior of composites of camptothecin and layered double hydroxide. J Solid State

392

Chem. 2010, 183, 1811-1816.

393

20.

394

395

equation and the sorbate intraparticle diffusivity. 2013, 1055-1064.

21.

396

397

Ramteke KH, Dighe PA, Kharat AR, Patil S V. Review Article Mathematical Models of Drug Dissolution : A Review. 2014, 3(5), 388-396.

22.

398

399

Plazinski W, Dziuba J. Modeling of sorption kinetics : the pseudo-second order

Singhvi G, Singh M. Review : In-Vitro Drug Release Characterization Models. 2011, II(I).

23.

Nguyen TX, Huang L, Liu L, Elamin M. Electronic Supplementary Information ( ESI )

400

Chitosan-coated nano-liposomes for the oral delivery of berberine hydrochloride. 2014,

401

1-4.

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

402

ACS Paragon Plus Environment

Page 18 of 30

Page 19 of 30

Journal of Agricultural and Food Chemistry

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.

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

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)

ACS Paragon Plus Environment

Page 21 of 30

Journal of Agricultural and Food Chemistry

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

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

A

a

B B

C

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

ACS Paragon Plus Environment

Page 22 of 30

Page 23 of 30

Journal of Agricultural and Food Chemistry

A

B

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

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

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

ACS Paragon Plus Environment

Page 25 of 30

Journal of Agricultural and Food Chemistry

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

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

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.

ACS Paragon Plus Environment

Page 26 of 30

Page 27 of 30

Journal of Agricultural and Food Chemistry

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

ACS Paragon Plus Environment

R2

0.9975

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

Journal of Agricultural and Food Chemistry

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