Bio-inspired Edible Superhydrophobic Interface for Reducing

Subscriber access provided by UNIV OF DURHAM

Article

Bio-inspired edible super-hydrophobic interface for reducing residual liquid food Yao Li, Jingran Bi, Siqi Wang, Tan Zhang, Xiaomeng Xu, Haitao Wang, Shasha Cheng, Bei-Wei Zhu, and Mingqian Tan J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.7b05915 • Publication Date (Web): 14 Feb 2018 Downloaded from http://pubs.acs.org on February 15, 2018

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 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 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 29

Journal of Agricultural and Food Chemistry

1

Bio-inspired

edible

super-hydrophobic

2

reducing residual liquid food

interface

for

3 4

Yao Li,abc Jingran Bi,ab Siqi Wang,ab Tan Zhang,ab Xiaomeng Xu,ab Haitao Wang,ab Shasha Cheng,ab

5

Bei-Wei Zhuabc* and Mingqian Tanab*

6 7

a

8

District, Dalian, Liaoning 116034, People’s Republic of China

9

b

School of Food Science and Technology, Dalian Polytechnic University, Qinggongyuan1, Ganjingzi

National Engineering Research Center of Seafood, Dalian, Liaoning 116034, People’s Republic of

10

China

11

c

12

266000, People’s Republic of China

State Key Laboratory of Bioactive Seaweed Substances, Huangdao district, Qingdao, Shandong,

13 14

*Corresponding author (Tel& Fax: +86-411-86318657, E-mail: [email protected];

15

[email protected], ORCID: 0000000275350035).

16 17

ACS Paragon Plus Environment


18

Abstract:

19

Significant wastage of residual liquid food, such as milk, yogurt, and honey, in food container has

20

attracted great attention. In this work, a bio-inspired edible super-hydrophobic interface was fabricated

21

using the FDA-approved and edible honeycomb wax, arabic gum, and gelatin by a simple and low-cost

22

method. The bio-inspired edible super-hydrophobic interface showed multiscale structures, which were

23

similar to that of lotus leaf surface. This bio-inspired edible super-hydrophobic interface displayed high

24

contact angles for a variety of liquid foods and the residue of liquid foods could be effectively reduced

25

using the bio-inspired interface. To improve the adhesive force of the super-hydrophobic interface, a

26

flexible edible elastic film was fabricated between the interface and substrate materials. After being

27

repeatedly folded and long-time flushed, the interface still maintained excellent super-hydrophobic

28

property. The bio-inspired edible super-hydrophobic interface showed a good biocompatibility which

29

may have potential applications as a functional packaging interface material.

30 31 32 33 34 35 36 37 38 39


Page 2 of 29

Page 3 of 29


40

1. Introduction

41

In recent years, great efforts have been made to alleviate the global food crisis.1-2 Nevertheless,

42

there is a significant waste of residual liquid foods such as milk, yogurt, and honey adhered to the

43

inside of food container when they are poured out. If the residual liquid food in the container can be

44

reduced, it would be helpful to save food. One strategy to reduce the residual liquid food is to employ

45

bio-inspired super-hydrophobic films, which are extremely repellent to water and can reduce the

46

adhesion between the container and liquid food products. 3-5

47

The inspiration of bio-inspired super-hydrophobic film comes from the natural world. In the long

48

evolutionary process, certain plant leaf like lotus (Nelumbo nucifera) exhibits special wettability, to

49

avoid the adhesion of residual water.6-7 On the surface of lotus leaf, water droplets are almost spherical

50

and can roll freely. The special wettability of lotus leaf is due to two main factors: chemical

51

composition to impart low solid surface energy, and multiscale structures to enhance hydrophobicity on

52

the lotus leaf surface. The cooperation of the chemical composition and multiscale structures result in

53

an excellent super-hydrophobicity, resulting in a high water contact angle and a small sliding angle.8-15

54

For special wettability, many strategies have been developed to construct the super-hydrophobic

55

surfaces by an electrostatic spinning technique to manufacture micro/nanoscale structures using

56

hydrophobic polymer.16-19 However, the electrostatic spinning technique is prohibitively expensive,

57

high-voltage and uncontrollable in large-area fabrication. The other attractive approach is the use of

58

long-chain fluorocarbon materials with low surface energy.20-21 However, the long-chain fluorocarbon

59

material has safety concern to humans due to its bio-accumulative and toxic effects. Therefore, an ideal

60

super-hydrophobic surface material should be non-toxic and edible, thus eliminating toxicity of the film

61

materials during food applications.22-26 In addition, the preparation method of super-hydrophobic



62

surface should be simple, low cost and controllable in large-area fabrication for potential commercial

63

applications. The traditional preparation methods of super-hydrophobic surface are not suitable for the

64

flexible surface of food applications.27-29 Therefore, it is a great challenge to design and develop an

65

ideal super-hydrophobic interface on a flexible surface in food packing.

66

In this work, edible honeycomb wax, a U.S. food and Drug Administration (FDA)-approved and

67

edible material, was used as main matrix material to fabricate super-hydrophobic interface by a simple

68

microemulsion spraying method.30 A unique microstructure of honeycomb wax was formed via the

69

simple, low-cost and scalable spray-coating process. The formed honeycomb wax interface possesses

70

super-hydrophobic property on which water and liquid food products including Lipton green tea,

71

Gatorade, Coca-Cola, orange juice, whole milk, coffee and honey can roll freely in all directions.

72

Moreover, an edible elastic film was fabricated between the honeycomb wax and matrix material, such

73

as plastic film, to enhance the adhesion of super-hydrophobic interface for the application in flexible

74

substrates. In vitro cytotoxicity test was carried out to investigate the viability of cells upon contacting

75

the super-hydrophobic interface. This is a significant attempt to apply natural food as a functional

76

packaging interface material.

77

2. Experimental

78

2.1 Materials

79

Lipton green tea, Gatorade, Coca-Cola, orange juice, whole milk, coffee (Nescafe® Smoovlatte

80

containing water, milk, instant coffee, sugar, thickener 460i and 466, stabilizer 500 ii, acidity regulator

81

331iii and emulsifier 473, flavouring essence) and honey were purchased from local grocery market

82

(Dalian, China). Arabic gum, gelatin (from porcine skin), honeycomb wax and 3-(4,

83

5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) were purchased from Aldrich


Page 4 of 29

Page 5 of 29


84

Chemical Co. (Shanghai, China). Mouse osteoblast cell line was purchased from the Cell Bank of Type

85

Culture Collection of the Chinese Academy of Sciences (Shanghai, China). Unless otherwise stated,

86

acetone and other chemicals were purchased from commercial vendors and used without further

87

purification.

88

2.2 Preparation of edible elastic film

89

The edible super-hydrophobic interface was prepared as outlined in Scheme 1. Arabic gum (0.6 g)

90

and 8 mL water were mixed in a 50 mL round-bottom flask. After the Arabic gum was dissolved,

91

gelatin (0.2 g), glycerine (0.4 g) and 8 mL water were added. The mixture was mixed and heated at

92

50 °C for 12 h and filtered to remove the undissolved solid. The matrix material (7.5 cm x 7.5 cm)

93

plastic (or glass) was thoroughly rinsed with ethanol and deionized water and subsequently dried using

94

nitrogen gas. The mixture (0.5 mL) was added dropwise to the surface of the plastic while it was hot. A

95

thin uniform film was formed after swing lightly. After cooling at room temperature overnight, the

96

edible elastic film was obtained.

97

2.3 Preparation of edible super-hydrophobic interface

98

Honeycomb wax (1 mg), acetone (8 g) and n-hexane (1 g) were mixed in a 50 ml round-bottom

99

flask. The mixture was heated to reflux and the temperature was maintained for 1 h. After the reaction

100

was completed, the mixture was colorless and transparent. Ethanol (11 g) was added dropwise to the

101

mixture within half an hour. The mixture was then stirred for 1 h to obtain honeycomb wax emulsion

102

upon cooling to room temperature. And then, the honeycomb wax emulsions were sprayed onto the

103

surface of the edible elastic film, which were held at a distance of ~12 cm from the spray coater nozzle.

104

The pressure during spray coating was held constant at 30 psi. After being placed at room temperature

105

for 24 h to remove the solvent, the edible super-hydrophobic interface was obtained.



106 107

(Scheme 1) 2.4 Toxicity of edible super-hydrophobic interface

108

Mouse osteoblasts were cultured in serum-free medium(K-SFM) containing 10% fetal bovine

109

serum (FBS), at 37 °C, 5% CO2, and 95% humidity. The potential cytotoxicity of edible

110

super-hydrophobic interface was evaluated by a MTT assay. Mouse osteoblasts were treated with

111

different quality (0.2, 0.4, 0.8, 1.6 and 3.2 mg) honeycomb wax, and were incubated for 24 hours. Then,

112

the cells were treated with 0.02 mL of freshly prepared 2.5 mg/mL MTT, and incubated for 4 hours.

113

The supernatant was carefully removed, and dimethylsulfoxide solution was added. The cell viability

114

was calculated based on the absorbance measured at 570 nm.

115

2.5 Characterization

116

FT-IR spectra were recorded on a PerkinElmer Spectrum 10 FT-IR infrared spectrometer

117

(PerkinElmer, Norwalk, USA) in the wavelength range of 4000 to 1000 cm−1. Scanning electron

118

microscopy (SEM) was conducted on a JSM 7800F electron microscope (JEOL, Tokyo ,Japan) with the

119

primary electron energy of 15 kV. The contact angles of the cured samples were measured at 20 °C

120

using a sessile drop method on a dynamic contact angle measurement instrument JC2000C

121

(POWEREACH, Shanghai, China). The mechanical properties were characterized by Instron tension

122

tester (Model 5569, Norwood, USA) at a speed of 5 mm/min and compression test at a speed of 2

123

mm/min. Volatile organic solvents from the edible super-hydrophobic interface were analyzed using an

124

Agilent 7890A gas chromatography/ 5977A mass spectrometer (GC–MS) system (Palo Alto, CA, USA)

125

equipped with an Agilent HP-5-MS capillary column (30m×0.25 mm, 0.25 µm)

126 127

3. Result and Discussion


Page 6 of 29

Page 7 of 29


128 129

The wettability of a liquid can be characterized by the contact angle and contact angle hysteresis. For a smooth surface, the contact angle θ is given by Young’s formula as cos θ =

γ − γ γ

130

The contact angle θ of a liquid on a smooth surface is determined by the solid surface energy (γS),

131

liquid surface tension (γL) and solid liquid interfacial tension (γSL). A liquid displays the apparent

132

contact angle θ* and adopts model of the two possible states: Wenzel state or Cassie state as it contacts

133

a surface with multiscale structures. In the Wenzel state, the liquid penetrates multiscale structures and

134

wets surface completely, which is positive for a super-hydrophilic surface.31-32 In the Cassie state, air is

135

trapped between multiscale structures and liquid, which is positive to gain designing

136

super-hydrophobic surfaces due to the reduced solid-liquid contact area by the air pockets.33-35 As a

137

result in Cassie state, liquid shows high apparent advancing contact angles θ*adv, high apparent

138

receding contact angles θ*rec, and low contact angle hysteresis ∆θ*, which are necessary to reduce the

139

adhesion of liquid (when θ* ≥ 150° and ∆θ* ≤ 10°).

140

Figure 1a shows a large-scale SEM image of the surface of bio-inspired edible super-hydrophobic

141

interface. Many botryoid structures, uniformly distributed and arranged in a direction opposite to the

142

airflow direction of the spray coating, were found on the surface with diameters ranging from 60 to 90

143

µm. Figure 1b displayed a SEM image of the surface of botryoid structure. Many papillae were found

144

on the surface of the botryoidal in the size of 9 to 18 µm. The inset of Figure 1b shows a

145

high-resolution SEM image of the fold structures in nanometer scale on the surface of a papilla

146

structure. This result illustrated that the surface of the bio-inspired edible super-hydrophobic interface

147

was composed of multiscale structures, including the micron scale, sub-micron scale and nanometer

148

scale. These multiscale structures were the similar as the lotus leaf surface (Figure S1) which possesses



149

super-hydrophobic property with large water contact angle θ*.

150

As shown in Figure 2a, a smooth surface with honeycomb wax has relatively low water contact

151

angle θ* (around 85.0°), which is not suitable for application of super-hydrophobic interface. With a

152

sufficient surface coverage of the multiscale structures, the hydrophobicity of honeycomb wax surface

153

was improved significantly (θ* = 158.1°, ∆θ* = 7° for water, Figure 2b), at surface density (ρs) (weight

154

of honeycomb wax of the coating per unit area) ≈ 0.55 mg/cm2. It is noteworthy that liquid contacted

155

the hydrophilic edible elastic layer and resulted in the decrease of water contact angle θ* while the

156

surface coverage was insufficient (ρs ≤ 0.55 mg/cm2) (Figure 2c). At the same time, the increase of ρs

157

did not change the multiscale structures, and the water contact angle θ* did not change significantly (ρs

158

≥ 0.75 mg/cm2). This result illustrated that multiscale structures with appropriate density on coating

159

surface was necessary for super-hydrophobic property of coating interface.

160

Application of the bio-inspired edible super-hydrophobic interface was to reduce the residual

161

liquid food in food containers after being poured out. Liquid food has lower γL than water (γL = 72

162

mN/m), such as Coca-Cola (γL = 59 mN/m), Lipton green tea (γL = 69 mN/m), whole milk (γL = 48

163

mN/m), apple juice (γL = 57 mN/m), wine (γL = 53 mN/m), beer (γL = 52 mN/m), Gatorade (γL = 68

164

mN/m), and coffee [γL = 46 mN m−1]. To validate the bio-inspired edible super-hydrophobic interface

165

can effectively reduce the residual liquid food in food container, the wetting behavior of liquid food

166

was evaluated by different γL liquid food. As shown in Figure3, the liquid foods all have large contact

167

angle (θ* ≥ 150° and ∆θ* ≤ 10°), but the coffee (θ* = 139.6° and ∆θ* = 21°). The coffee is the

168

commercial NESCAFÉ Smoovlatte, which is an aromatic blend of NESCAFÉ and milk, and it contains

169

stabilizer and emulsifier that can change the Cassie state of multiscale structures.

170


Page 8 of 29

Page 9 of 29


171 172

To demonstrate the super-hydrophobic property of the interface in practical application, common

173

polystyrene cups were employed as the matrix for the super-hydrophobic interface. The cups were

174

filled with high viscosity liquid food honey (Figure 4). Subsequently, upon tipping the liquid foods out,

175

the cups with the super-hydrophobic interface facilitated removal of liquid food without residue. In

176

contrast, the control cups without coating super-hydrophobic interface exhibited significant residual

177

honey. This is due to the cups with the super-hydrophobic interface has an excellent super-hydrophobic

178

(θ* = 142.6° for honey). In contrast, water contact angle θ* of honey on the surface of control cup was

179

only 64.8°. The result suggested that the super-hydrophobic interface fabricated using edible material

180

could effectively reduce the honey residue. The parameters of super-hydrophobic interface with

181

different liquid foods were listed in Table 1.

182

The bio-inspired edible super-hydrophobic interface with simple multiscale structures of

183

honeycomb wax is not competent for the practical application. The small γS of honeycomb wax results

184

in poor adhesion with substrates and the honeycomb wax is broken off easily from the substrate. The

185

edible elastic film could effectively connect multiscale structures and the substrates to prevent the

186

peeling of multiscale structures. As shown in Figure 5, a significant decrease of water contact angle θ*

187

of the super-hydrophobic interface was found for the coating layer without edible elastic film after

188

long-time flushing. In contrast, with the support of edible elastic film, the water contact angle θ* of the

189

super-hydrophobic interface did not decrease significantly. This result suggested that the edible elastic

190

film was effective to increase the compatibility between honeycomb wax and substrate.

191

In order to explain the strengthening effect of the edible elastic film, the FT-IR spectra of edible

192

elastic film and honeycomb wax were measured (Figure 6a). A broad and intense peak at 3200-3600



193

cm−1 was attributed to the –NH2 and –OH stretching. The band at 2920 and 2849 cm−1 was attributed to

194

–CH2 stretching vibrations. Typical absorption peak of amide groups appeared at 1648 cm−1 in edible

195

elastic film. The band at 1737 cm−1 was associated with the stretching of the ester groups in the

196

honeycomb wax. The presence of lots of hydroxyl and amidogen groups in the edible elastic film can

197

form the hydrogen bonding with ester groups of honeycomb wax, and thus increase the adhesion

198

between them.36-40 The binding mechanism of edible elastic film under the bio-inspired

199

super-hydrophobic interface was shown in Figure 6b. The honeycomb wax interacted with the edible

200

elastic film by the hydrogen bond and van der Waals force via functional groups on their surface. The

201

edible elastic film achieved a high compressive stress of more than 0.18 MPa and its normal

202

compressive stress is more than 50% with no-damage after compression (Figure 6c). At the same time,

203

an excellent tensile strength (30 KPa) was indispensable when edible elastic film was used for practical

204

applications (Figure 6d). The high energy storage modulus and tensile strength of edible elastic film

205

was effective to absorb and protect the impact multiscale structures.

206

For a wide range of applications, the bio-inspired edible super-hydrophobic interface was prepared

207

on the flexible substrate of plastic (Figure 7a). The bio-inspired edible super-hydrophobic interface

208

showed a relatively big water contact angle θ* (Figure 7b). Importantly, the water contact angle θ* of

209

super-hydrophobic interface was still more than 140

210

super-hydrophobic interface fabricated was successfully applied to flexible substrate. Temperature, pH

211

and time stability of the super-hydrophobic interfaces were shown in Figure S2, S3 and S4, respectively.

212

The results showed that such film/coating was insensitive to pH value in the solution and were stable

213

for as long as 30 days. However, the contact angle θ of the edible super-hydrophobic interface reduced

214

significantly when heated at 60 or 90 oC for 10 minutes.

o

after repeated folding. This suggests that the


Page 10 of 29

Page 11 of 29


215

For the food applications, the potential cytotoxicity of the super-hydrophobic interface was

216

evaluated

217

dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide. Figure 8 shows that the relative cell viability is

218

around 100% after the cells being incubated with the material of super-hydrophobic interface at the

219

concentration as high as 15 mg/mL for 72 h. This demonstrated that the material of super-hydrophobic

220

interface was not toxic to mouse osteoblasts. In addition, the gas chromatography-mass spectrometry

221

analysis (Figure S5) suggested that the super-hydrophobic interface didn’t contain volatile organic

222

solvent residue, such as acetone and n-hexane used for the preparation of films. This is a very

223

important issue for the use of this coating technique for food.

against

mouse

osteoblasts

via

the

MTT

assay

using

3-[4,5-

224

This study demonstrated a simple and low-cost method to fabricate the bio-inspired edible

225

super-hydrophobic interface. The super-hydrophobic interface exhibited high θ* and low ∆θ* for water

226

with an appropriate coating density on surface. The result shows that most liquid testing food has large

227

contact angle on the super-hydrophobic interface, except those which contain emulsifiers. For the

228

application on flexible substrates, an edible elastic film was fabricated between the honeycomb wax

229

and substrate material, which was proved to be effective to enhance the adhesive force of

230

super-hydrophobic interface. Although the bio-inspired edible super-hydrophobic interface displayed

231

reasonable mechanical durability, the interface was able to maintain good super-hydrophobic property

232

after being repeatedly folded and long-time flushed. The cytotoxicity tests indicated that there was no

233

negative effect on the viability of cells in vitro. This bio-inspired edible super-hydrophobic interface

234

would have applications in reducing the residue of high value-added liquid foods.

235

ASSOCIATED CONTENT

236

Supporting Information



237 238

The Supporting Information is available free of charge on the ACS Publications website at DOI: XXXXXXX.

239

Water flushing test, tensile stress–strain experiment, SEM image of the lotus leaf surface,

240

temperature, pH and time effects on contact angle θ of super-hydrophobic interface, gas

241

chromatography-mass spectrum of the residual organic solvent analysis for super-hydrophobic

242

interface.

243

AUTHOR INFORMATION

244

Corresponding Author

245

* E-mail: [email protected] (B.-W. Z.); M. Tan, [email protected] (M. T.)

246

ORCID

247

Mingqian Tan: 0000000275350035

248

Funding

249

This work was supported by the National Natural Science Foundation of China (31601389) and the

250

National Key Research and Development Project (2017YFD0400100, 2016YFD0400404).

251

Notes

252

The authors declare no competing ﬁnancial interest.

253 254 255

References (1)

Wang, W.; Lockwood, K.; Boyd, L. M.; Davidson, M. D.; Movafaghi, S.; Vahabi, H.;

256

Khetani, S. R.; Kota, A. K. Superhydrophobic coatings with edible materials. ACS Appl. Mater.

257

Interfaces 2016, 8, 18664-18668.

258

(2)

Williams, H.; Wikström, F. Environmental impact of packaging and food losses in a life


Page 12 of 29

Page 13 of 29


259 260

cycle perspective: a comparative analysis of five food items. J. Clean. Prod. 2011, 19, 43-48. (3)

Zhang, W.; Shi, Z.; Zhang, F.; Liu, X.; Jin, J.; Jiang, L. Superhydrophobic and

261

superoleophilic pvdf membranes for effective separation of water-in-oil emulsions with high flux. Adv.

262

Mater. 2013, 25, 2071-2076.

263

(4)

Cheng, Z.; Du, M.; Lai, H.; Zhang, N.; Sun, K. From petal effect to lotus effect: a facile

264

solution immersion process for the fabrication of super-hydrophobic surfaces with controlled adhesion.

265

Nanoscale 2013, 5, 2776-2783.

266

(5)

Seo, J.; Lee, S.; Han, H.; Jung, H. B.; Hong, J.; Song, G.; Cho, S. M.; Park, C.; Lee, W.; Lee,

267

T. Gas-driven ultrafast reversible switching of super-hydrophobic adhesion on palladium-coated silicon

268

nanowires. Adv. Mater. 2013, 25, 4139-4144.

269 270 271 272 273

(6)

Lin, F.; Shuhong, L.; Yingshun, L.; Lei, J. Super-hydrophobic surface: from natural to

artificial. Adv. Mater. 2002, 14, 1857-1860. (7)

Liu, K.; Jiang, L. Bio-inspired design of multiscale structures for function integration. Nano

Today 2011, 6, 155-175. (8)

Feng, L.; Zhang, Z.; Mai, Z.; Ma, Y.; Liu, B.; Jiang, L.; Zhu, D. A super-hydrophobic and

274

super-oleophilic coating mesh film for the separation of oil and water. Angew. Chem. 2004, 116,

275

2046-2048.

276

(9)

Joula, M. H.; Farbod, M. Synthesis of uniform and size-controllable carbon nanospheres by a

277

simple hydrothermal method and fabrication of carbon nanosphere super-hydrophobic surface. Appl.

278

Surf. Sci. 2015, 347, 535-540.

279 280

(10)

Gao, Z.; Zhai, X.; Liu, F.; Zhang, M.; Zang, D.; Wang, C. Fabrication of TiO2/EP

super-hydrophobic thin film on filter paper surface. Carbohydr. Polym. 2015, 128, 24-31.



281

(11)

Zhang, Y.; Wang, H.; Yan, B.; Zhang, Y.; Yin, P.; Shen, G.; Yu, R. A rapid and efficient

282

strategy for creating super-hydrophobic coatings on various material substrates. J. Mater. Chem. 2008,

283

18, 4442-4449.

284

(12)

Marini, M.; Allione, M.; Torre, B.; Moretti, M.; Limongi, T.; Tirinato, L.; Giugni, A.; Das, G.;

285

di Fabrizio, E. Raman on suspended dna: novel super-hydrophobic approach for structural studies.

286

Microelectron. Eng. 2017, 175, 38-42.

287

(13)

Gentile, F.; Coluccio, M. L.; Zaccaria, R. P.; Francardi, M.; Cojoc, G.; Perozziello, G.;

288

Raimondo, R.; Candeloro, P.; Di Fabrizio, E. Selective on site separation and detection of molecules in

289

diluted solutions with super-hydrophobic clusters of plasmonic nanoparticles. Nanoscale 2014, 6,

290

8208-8225.

291 292 293 294 295

(14)

Sahoo, B. N.; Kandasubramanian, B. Recent progress in fabrication and characterisation of

hierarchical biomimetic superhydrophobic structures. RSC Adv. 2014, 4, 22053-22093. (15)

He, M.; Wang, J.; Li, H.; Jin, X.; Wang, J.; Liu, B.; Song, Y. Super-hydrophobic film retards

frost formation. Soft Matter 2010, 6, 2396-2399. (16)

Shi, Z.; Zhang, W.; Zhang, F.; Liu, X.; Wang, D.; Jin, J.; Jiang, L. Ultrafast separation of

296

emulsified oil/water mixtures by ultrathin free-standing single-walled carbon nanotube network films.

297

Adv. Mater. 2013, 25, 2422-2427.

298 299 300

(17)

Liao, Y.; Loh, C. H.; Wang, R.; Fane, A. G. Electrospun superhydrophobic membranes with

unique structures for membrane distillation. ACS Appl. Mater. Interfaces 2014, 6, 16035-16048. (18)

Liu, Y.; Chen, J.; Guo, D.; Cao, M.; Jiang, L. Floatable, Self-cleaning, and

301

carbon-black-based superhydrophobic gauze for the solar evaporation enhancement at the air-water

302

interface. ACS Appl. Mater. Interfaces 2015, 7, 13645-13652.


Page 14 of 29

Page 15 of 29


303 304 305 306 307

(19)

Ye, L.; Guan, J.; Li, Z.; Zhao, J.; Ye, C.; You, J.; Li, Y. Fabrication of superhydrophobic

surfaces with controllable electrical conductivity and water adhesion. Langmuir 2017, 33, 1368-1374. (20)

Zhang, E.; Wang, Y.; Lv, T.; Li, L.; Cheng, Z.; Liu, Y. Bio-inspired design of hierarchical

pdms microstructures with tunable adhesive superhydrophobicity. Nanoscale 2015, 7, 6151- 6158. (21)

Li, X.; Yu, X.; Cheng, C.; Deng, L.; Wang, M.; Wang, X. Electrospun superhydrophobic

308

organic/inorganic composite nanofibrous membranes for membrane distillation. ACS Appl. Mater.

309

Interfaces 2015, 7, 21919-21930.

310

(22)

Fabra, M. J.; López-Rubio, A.; Lagaron, J. M. Use of the electrohydrodynamic process to

311

develop active/bioactive bilayer films for food packaging applications. Food Hydrocolloids 2016, 55,

312

11-18.

313

(23)

314 315

Jarzębski, M.; Bellich, B.; Białopiotrowicz, T.; Śliwa, T.; Kościński, J.; Cesàro, A. Particle

tracking analysis in food and hydrocolloids investigations. Food Hydrocolloids 2017, 68, 90-101. (24)

Beltrán, A.; Valente, A. J. M.; Jiménez, A.; Garrigós, M. a. C. Characterization of

316

poly(ε-caprolactone)-based nanocomposites containing hydroxytyrosol for active food packaging. J.

317

Agric. Food. Chem. 2014, 62, 2244-2252.

318

(25)

Liu, K.; Lin, X.; Chen, L.; Huang, L.; Cao, S.; Wang, H. Preparation of microfibrillated

319

cellulose/chitosan–benzalkonium chloride biocomposite for enhancing antibacterium and strength of

320

sodium alginate films. J. Agric. Food. Chem. 2013, 61, 6562-6567.

321

(26)

Sundaram, J.; Pant, J.; Goudie, M. J.; Mani, S.; Handa, H. Antimicrobial and

322

physicochemical characterization of biodegradable, nitric oxide-releasing nanocellulose–chitosan

323

packaging membranes. J. Agric. Food. Chem. 2016, 64, 5260-5266.

324

(27)

Lin, L.; Liu, M.; Chen, L.; Chen, P.; Ma, J.; Han, D.; Jiang, L. Bio-inspired hierarchical



325

macromolecule-nanoclay hydrogels for robust underwater superoleophobicity. Adv. Mater. 2010, 22,

326

4826-4830.

327 328 329

(28)

Azimi, G.; Dhiman, R.; Kwon, H. M.; Paxson, A. T.; Varanasi, K. K. Hydrophobicity of

rare-earth oxide ceramics. Nat. Mater. 2013, 12, 315-320. (29)

Li, K.; Ju, J.; Xue, Z.; Ma, J.; Feng, L.; Gao, S.; Jiang, L. Structured cone arrays for

330

continuous and effective collection of micron-sized oil droplets from water. Nat. Commun. 2013, 4.

331

2776-2782

332

(30)

C. R, R.; Sundaran, S. P.; A, J.; Athiyanathil, S. Fabrication of superhydrophobic

333

polycaprolactone/beeswax electrospun membranes for high-efficiency oil/water separation. RSC Adv.

334

2017, 7, 2092-2102.

335 336

(31)

2006, 18, 3063-3078.

337

(32)

338

291-292.

339

(33)

340 341 342 343

Feng, X. J.; Jiang, L. Design and creation of superwetting/antiwetting surfaces. Adv. Mater.

Tian, Y.; Jiang, L. Wetting: intrinsically robust hydrophobicity. Nat. Mater. 2013, 12,

Liu, M.; Wang, S.; Wei, Z.; Song, Y.; Jiang, L. Bioinspired design of a superoleophobic and

low adhesive water/solid interface. Adv. Mater. 2009, 21, 665-669. (34)

Su, B.; Wang, S.; Song, Y.; Jiang, L. A miniature droplet reactor built on

nanoparticle-derived superhydrophobic pedestals. Nano Research 2010, 4, 266-273. (35)

Zhang, S.; Huang, J.; Tang, Y.; Li, S.; Ge, M.; Chen, Z.; Zhang, K.; Lai, Y. Understanding

344

the role of dynamic wettability for condensate microdrop self-propelling based on designed

345

superhydrophobic tio2 nanostructures. Small 2017, 13, 1600687-1600694.

346

(36)

Zhi, H.; Fei, X.; Tian, J.; Jing, M.; Xu, L.; Wang, X.; Liu, D.; Wang, Y.; Liu, J. A novel


Page 16 of 29

Page 17 of 29


347 348

transparent luminous hydrogel with self-healing property. J. Mater. Chem. B 2017, 5, 5738-5744. (37)

Jing, M.; Fu, Y.; Fei, X.; Tian, J.; Zhi, H.; Zhang, H.; Xu, L.; Wang, X.; Wang, Y. A novel

349

high-strength polymer hydrogel with identifiability prepared via a one-pot method. Polym. Chem. 2017,

350

8, 3553-3559.

351 352 353

(38)

Siripatrawan, U.; Vitchayakitti, W. Improving functional properties of chitosan films as

active food packaging by incorporating with propolis. Food Hydrocolloids 2016, 61, 695-702. (39)

Du, W.; Shao, H.; He, Z.; Tang, C.; Liu, Y.; Shen, T.; Zhu, Y.; Lau, W.-m.; Hui, D.

354

Cross-linking poly(lactic acid) film surface by neutral hyperthermal hydrogen molecule bombardment.

355

J. Agric. Food. Chem. 2015, 63, 10604-10610.

356

(40)

Farris, S.; Introzzi, L.; Fuentes-Alventosa, J. M.; Santo, N.; Rocca, R.; Piergiovanni, L.

357

Self-assembled pullulan–silica oxygen barrier hybrid coatings for food packaging applications. J. Agric.

358

Food. Chem. 2012, 60, 782-790.

359 360



361

Figure captions:

362

Scheme 1 Fabrication process of edible super-hydrophobic interface.

363

Figure 1 (a) large-scale SEM images of edible super-hydrophobic interface. (b) SEM image of a papilla

364

structure on the surface of botryoid structures (inset shows the HRTEM image of the surface of a

365

papilla structure).

366

Figure 2 Water contact angle θ* of (a) unprocessed honeycomb wax and (b) super-hydrophobic

367

interface with multiscale structures. (c) Water contact angle θ* of super-hydrophobic interface with a

368

different surface density of honeycomb wax.

369

Figure 3 Water contact angle θ* of edible super-hydrophobic interface with the different commercial

370

liquid foods, (a) Coca-Cola, (b) Lipton green tea, (c) whole milk, (d) apple juice, (e) wine, (f) beer, (g)

371

Gatorade, and (h) coffee.

372

Figure 4 Photographs of representative liquid food in an uncoated cup (left) and super-hydrophobic

373

interface coated cup (right) before (a) and after (b) tipping honey out.

374

Figure 5 Water contact angle θ of edible super-hydrophobic interface with/without the edible elastic

375

film during different flushing time.

376

Figure 6 (a) FT-IR spectra of honeycomb wax and edible elastic layer. (b) Enhancement mechanism of

377

honeycomb wax and edible elastic film. (c) Pressure curve of the edible elastic film. Insets show the

378

film before and after being pressured. (d) Tensile stress–strain curve of the edible elastic film.

379

Figure 7 (a) Photograph of edible super-hydrophobic interface on a flexible substrate polypropylene. (b)

380

Water contact angle θ of edible super-hydrophobic interface with a different folding frequency.

381

Figure 8 Cytotoxicity of the honeycomb wax against mouse osteoblasts evaluated with MTT assay.

382


Page 18 of 29

Page 19 of 29


383 384

Scheme 1

385



386 387

Figure 1

388


Page 20 of 29

Page 21 of 29


389 390

Figure 2

391



392 393

Figure 3

394


Page 22 of 29

Page 23 of 29


395 396

Figure 4

397



398 399

Figure 5

400


Page 24 of 29

Page 25 of 29


401 402

Figure 6

403



404 405

Figure 7

406


Page 26 of 29

Page 27 of 29


140

Cell viability (%)

120 100 80 60 40 20 0 0

5

10

15

Concentration of honeycomb wax (mg/mL) 407 408

Figure 8

409



410 411

Page 28 of 29

Table 1 Parameters of super-hydrophobic interface with various liquid foods.

Items

Energy Coke

Lipton tea

Whole milk

Fruit juice

Wine

Beer

Nestle coffee

Honey

drinks Contact angle θ* on the glass surface 53.4±1.8

63.5±2.1

46.3±1.8

51.0±1.1

54.5±0.9

47.8±1.3

58.1±2.4

43.7±1.1

64.8±2.1

154.2±1.5

158.4±0.8

150.6±1.2

153.9±2.5

152.1±2.3

151.4±1.6

158.1±0.9

139.6±2.4

142.6±1.9

0.878±0.10

1.180±0.24 1.483±0.317

1.066±0.092

1.181±0.103

0.881±0.107

1.327±0.132

8

5

0.007±0.00

0.038±0.01

2

68

(°) Contact angle θ* on the surface of super-hydrophobic interface (°) Residual liquid food (15 g) on the glass 0.981±0.117 surface (g)

2.759±0.1 01

Residual liquid food (15 g) on the surface of super-hydrophobic interface

0.018±0.163

0.162±0.0 0.012±0.006

0.015±0.010

(g)

412


0.013±0.006

0.006±0.003

0.111±0.017 39

Page 29 of 29


413

Table of Contents Graphic

414


Bio-inspired Edible Superhydrophobic Interface for Reducing

Recommend Documents