Picosecond Laser Generation and Modification of Ag-TiO2 Nanoparticles for Antibacterial Application

293 Pages·2017·8.29 MB·English

Article I.

Picosecond Laser Generation
and Modification of Ag-TiO
2
Nanoparticles for Antibacterial
Application
A thesis submitted to
The University of Manchester
for the degree of
Doctor of Philosophy (PhD)
in the Faculty of Science and Engineering

2016

Abubaker Hassan Hamad

School of Mechanical, Aerospace and Civil
Engineering
1
Table of Contents

Table of contents ……………………………………………………………………. 2
List of Figures …………………………………………………………………………7
List of Tables …………………………………………………………………………15
Abstract ……………………………………………………………………………….16
Declaration …………...………………………………………………………………17
Copyright statement …………………………………………………………………18
Acknowledgments ……………………………...……………………………….......19
List of abbreviations …………………………………………………………………20
List of publications ……………………...…………………………………………...21
Chapter 1. INTRODUCTION ............................................................... 22
1.1. Overview ................................................................................................. 22
1.2. Problem statement .................................................................................. 23
1.3. Research Aim and Objectives ................................................................ 23
1.4. Scientific challenges ............................................................................... 24
1.5. Outline of Thesis ..................................................................................... 27
1.6. Logical development of the research ...................................................... 29
Chapter 2. Literature review .............................................................. 31
2.1. Introduction to nanoparticles ................................................................... 31
2.1.1. Overview .......................................................................................... 31
2.1.2. Classification of nanoparticles .......................................................... 34
2.1.3. Toxicity and health hazard of nanoparticles ..................................... 37
2.1.4. Properties of nanoparticles ............................................................... 39
2.1.5. Nanoparticle production techniques ................................................. 41
2.1.6. Characterisation of nanoparticles ..................................................... 49
2.1.7. Applications of nanoparticles ............................................................ 50
2.2. Lasers, laser-material interaction and nanoparticles generation ............. 51
2.2.1. Introduction ....................................................................................... 51
2.2.2. Laser and laser beam properties ...................................................... 51
2.2.3. Ultra-short pulse lasers ..................................................................... 52
2.2.4. Ablation process ............................................................................... 53
2.2.5. Laser–water interaction .................................................................... 53
2.2.6. Laser–material interaction ................................................................ 54
2.2.7. Generation of nanoparticles in water with a laser beam ................... 57
2
2.3. Effects of laser beam parameters and ablation environments on Ag and
TiO nanoparticle production ......................................................................... 59
2
2.3.1. Introduction ....................................................................................... 59
2.3.2. Silver nanoparticles .......................................................................... 59
2.3.3. Titanium dioxide nanoparticles ......................................................... 63
2.3.4. Ag-modified TiO .............................................................................. 65
2
2.3.5. Nanoparticle generation by laser ablation in liquid environments ..... 68
2.4. Antimicrobial and photocatalytic activities of Ag modified TiO
2
nanoparticles ................................................................................................. 74
2.4.1. Introduction ....................................................................................... 74
2.4.2. Antibacterial activity of Ag nanoparticles .......................................... 74
2.4.3. Photocatalytic activity of TiO nanoparticles ..................................... 76
2
2.4.4. Antimicrobial activity of Ag-modified TiO ......................................... 77
2
2.4.5. Knowledge gap in the literature review ............................................. 85
2.4.6. Summary .......................................................................................... 85
Chapter 3. Picosecond laser generation of Ag-TiO nanoparticles with
2
reduced energy gap by ablation in ice water and their antibacterial
activities ......................................................................................... 91
3.1. Introduction ............................................................................................. 93
3.2. Experimental set-up ................................................................................ 95
3.2.1. Materials ........................................................................................... 95
3.2.2. Nanoparticle production .................................................................... 95
3.2.3. Sample preparation .......................................................................... 96
3.2.4. Characterisation ............................................................................... 96
3.2.5. Antibacterial function testing procedure ............................................ 97
3.3. Energy gap calculation ........................................................................... 97
3.4. Results .................................................................................................... 99
3.4.1. The characteristics of Ag-TiO nanoparticles.................................... 99
2
3.4.2. Characteristics of TiO nanoparticles ............................................. 103
2
3.4.3. Antibacterial Activity ....................................................................... 104
3.5. Discussion ............................................................................................ 105
3.6. Summary .............................................................................................. 107
Chapter 4. The Characteristics of Novel Bimodal Ag-TiO2 Nanoparticles
Generated by Hybrid Laser-Ultrasonic Technique ............................. 109
4.1. Introduction ........................................................................................... 111
4.2. Experimental materials and procedures ............................................... 113
4.2.1. Materials ......................................................................................... 113
4.2.2. Preparation of Ag-TiO nanoparticles by hybrid ultrasonic sonication
2
and laser ablation ..................................................................................... 113
3
4.2.3. Nanoparticle sample preparation for characterisation .................... 115
4.2.4. Characterisation ............................................................................. 115
4.2.5. Antibacterial Activity Test Procedure .............................................. 116
4.3. Results .................................................................................................. 117
4.3.1. Ag-TiO nanoparticle characteristics .............................................. 117
2
4.3.2. Ag-TiO nanoparticles generation without ultrasonic vibration ....... 122
2
4.3.3. The characteristics of TiO nanoparticles generated with ultrasonic
2
vibration .................................................................................................... 122
4.3.4. The characteristics of laser generated Ag nanoparticles ................ 123
4.3.5. Antibacterial characteristics ............................................................ 124
4.4. Discussion ............................................................................................ 126
4.4.1. Generation of Ag-TiO cluster and TiO Nanoparticles ................... 126
2 2
4.4.2. Ag and TiO combination ................................................................ 128
2
4.4.3. Antibacterial activity ........................................................................ 130
4.5. Summary .............................................................................................. 131
Chapter 5. Generation of Silver Titania Nanoparticles from Ag-Ti alloy via
Picosecond Laser Ablation and their Antibacterial Activities .............. 132
5.1. Introduction ........................................................................................... 134
5.2. Experimental set-up .............................................................................. 136
5.2.1. Materials ......................................................................................... 136
5.2.2. Ag-TiO compound nanoparticle production ................................... 136
2
5.2.3. Material Characterisation ................................................................ 137
5.2.4. Antibacterial activity analysis .......................................................... 138
5.3. Results and discussion ......................................................................... 139
5.3.1. Bulk Ti/Ag alloy characterisation .................................................... 139
5.3.2. Ag-TiO compound nanoparticles ................................................... 141
2
5.3.3. Sedimentation and zeta-potentials of nanoparticles ....................... 150
5.3.4. Antibacterial activity ........................................................................ 154
5.4. Summary .............................................................................................. 158
Chapter 6. Sequential laser and ultrasonic wave generation of TiO2@Ag
core-shell nanoparticles and their anti-bacterial properties ................ 160
6.1. Introduction ........................................................................................... 162
6.2. Experimental set-up .............................................................................. 164
6.2.1. Materials ......................................................................................... 164
6.2.2. Ag-TiO compound and TiO @Ag core-shell nanoparticle production
2 2
................................................................................................................. 164
6.2.3. Material characterisation ................................................................ 166
6.2.4. Antibacterial activity analysis .......................................................... 167
4
6.3. Results .................................................................................................. 167
6.3.1. Ag-TiO compound and TiO @Ag core-shell nanoparticle production
2 2
................................................................................................................. 167
6.3.2. XRD of Ag-TiO compound and TiO @Ag core-shell nanoparticles
2 2
................................................................................................................. 172
6.3.3. Sonication of mixed and added Ag and TiO nanoparticles ............ 172
2
6.3.4. Antibacterial activity ........................................................................ 173
6.4. Discussion ............................................................................................ 175
6.4.1. Core-shell and compound nanoparticles ........................................ 175
6.4.2. Antibacterial activity ........................................................................ 178
6.5. Summary .............................................................................................. 180
Chapter 7. Comparison of characteristics of Ag-TiO nanoparticles
2
produced from an Ag-Ti alloy using nano-, pico- and femtosecond lasers
and their antibacterial activities ....................................................... 181
7.1. Introduction ........................................................................................... 183
7.2. Experimental materials and procedures ............................................... 185
7.2.1. Materials ......................................................................................... 185
7.2.2. Ag-TiO nanoparticles production methods .................................... 185
2
7.2.3. Sample preparation for nanoparticle characterisation .................... 186
7.2.4. Characterisation ............................................................................. 186
7.2.5. Antibacterial test procedure ............................................................ 187
7.3. Results and discussion ......................................................................... 188
7.3.1. Ag-TiO nanoparticle generation by nano-, pico and femtosecond
2
laser ablation ............................................................................................ 188
7.3.2. XRD of Ag-TiO compound nanoparticles ...................................... 191
2
7.3.3. FTIR spectra of Ag-TiO compound nanoparticles ......................... 192
2
7.3.4. Raman shift of Ag-TiO compound nanoparticles ........................... 193
2
7.3.5. XPS analysis of Ag-TiO chemical structures ................................. 194
2
7.3.6. Antibacterial activity ........................................................................ 197
7.4. Summary .............................................................................................. 199
Chapter 8. A comparison of the characteristics of nanosecond,
picosecond and femtosecond laser generated Ag, TiO2 and Au
nanoparticles in deionised water ..................................................... 200
8.1. Introduction ........................................................................................... 202
8.2. Experimental Materials and Procedure ................................................. 203
8.2.1. Materials ......................................................................................... 203
8.2.2. Lasers ............................................................................................. 204
8.2.3. Nanoparticle production procedure ................................................ 204
8.2.4. Material characterisation methods .................................................. 205
5
8.3. Results and discussion ......................................................................... 205
8.3.1. Optical reflectivity of Ag, Ti and Au target materials ....................... 205
8.3.2. Laser ablation material removal rate in deionised water as a function
of laser fluence and water level ................................................................ 206
8.3.3. Comparison between nano- pico- and femtosecond laser generation
of nanoparticles ........................................................................................ 208
8.3.4. Morphology of the nanoparticles .................................................... 212
8.3.5. Understanding the absorption spectra of colloidal nanoparticles .... 213
8.3.6. Ablation rates ................................................................................. 214
8.3.7. Size distribution and average nanoparticle sizes ............................ 218
8.3.8. Colour of colloidal nanoparticles ..................................................... 221
8.3.9. Ablation mechanism by the nano-, pico- and femtosecond lasers .. 222
8.4. Summary .............................................................................................. 223
Chapter 9. Comparison of characteristics of selected metallic and metal
oxide nanoparticles produced by picosecond laser ablation at 532 nm and
1064 nm wavelengths ..................................................................... 224
9.1. Introduction ........................................................................................... 226
9.2. Experimental Materials and Procedure ................................................. 228
9.2.1. Materials ......................................................................................... 228
9.2.2. Nanoparticle Production Procedure ................................................ 229
9.2.3. Material Characterisation and Sample Preparation Procedure ....... 230
9.3. Results .................................................................................................. 231
9.3.1. Au Nanoparticles ............................................................................ 231
9.3.2. Ag-TiO Compound Nanoparticles ................................................. 232
2
9.3.3. TiO Nanoparticles ......................................................................... 233
2
9.3.4. Iron Oxide Nanoparticles ................................................................ 235
9.3.5. ZnO Nanoparticles.......................................................................... 237
9.3.6. Ag Nanoparticles ............................................................................ 239
9.4. Discussion ............................................................................................ 240
9.4.1. Effects of Wavelengths on the Size of the Nanoparticles ............... 240
9.4.2. Effects of Wavelengths on the Crystallinity of Metal Oxide
Nanoparticles ........................................................................................... 246
9.5. Summary .............................................................................................. 248
Chapter 10. A Single-step Process of Generating Hollow and Porous TiO2
Nanoparticles by Picosecond Laser Ablation in Deionised Water ........ 249
10.1. Introduction ......................................................................................... 251
10.2. Experimental set-up ............................................................................ 253
10.2.1. Nanoparticle production ................................................................ 253
10.2.2. Sample preparation ...................................................................... 254
6
10.2.3. Characterisation ........................................................................... 254
10.3. Results and discussion ....................................................................... 255
10.3.1. Generation of hollow TiO nanoparticles ...................................... 255
2
10.3.2. Effect of laser power on the production of hollow/ porous TiO
2
nanoparticles ............................................................................................ 260
10.3.3. Effect of laser power on the optical properties of hollow/porous TiO
2
nanoparticles ............................................................................................ 261
10.3.4. XRD of hollow/porous TiO nanoparticles .................................... 262
2
10.4. Summary ............................................................................................ 263
Chapter 11. Conclusions ................................................................ 264
11.1. Conclusions ........................................................................................ 264
Chapter 12. Future Work ................................................................. 267
12.1. Future work recommendations ........................................................... 267

List of Figures

Figure 2-1 Comparison of “nano” and “micro” length scales and 32
biological components [24].
Figure 2-2 The most common nanoparticle categories [28] 33
Figure 2-3 3, 2, 1 and 0 dimensions of materials and the density of 35
their states as a function of energy [35]
Figure 2-4 Classification of nanomaterials on the basis of morphology 36
[24]
Figure 2-5 Classification of nanomaterials on the basis of uniformity 36
and agglomeration [24].
Figure 2-6 Variation in melting point of gold nanoparticles with the 41
particles’ diameter [24]
Figure 2-7 Methods of nanoparticle generation: break down (top– 43
down) and build up (bottom-up) a [75] and b [76]
Figure 2-8 Top – down method for production nanoparticles [76] 44
Figure 2-9 Bottom–up process for the generation of nanoparticles [76] 45
Figure 2-10 The phases and reactions of the sol-gel method [76] 47
Figure 2-11 Effect of water height on the ablation rate [92] 54
Figure 2-12 Absorption process within matter as a function of 56
increasing power [90]
Figure 2-13 The interaction processes of ns, ps and fs laser pulses with 57
materials as a function of intensity [95]
Figure 2-14 The physical stages of TiO nanoparticle generation [87] 58
Figure 2-15 Absorption spectra of Ag nanoparticles [51] 60
Figure 2-16 X-ray diffraction spectrum of pulsed laser deposition of a 63
thin film of TiO and the three crystal phases of TiO
2 2
(anatase (A), rutile (R) and brookite (B)) [106]
Figure 2-17 Band gap dependence on doping agent concentration [109] 65
Figure 2-18 Absorption spectra of TiO NPs and Ag-deposited TiO 66
2 2
7
particles in water [124]
Figure 2-19 The mechanism of the photocatalytic properties of TiO 77
2
[159]
Figure 2-20 The mechanism of antimicrobial activity of Ag-TiO 79
2
nanocomposites (a) [115] (b) [168].
Figure 2-21 Antimicrobial activity of Ag NPs against S. aureus and E. 80
coli (A and B) and TiO NPs against S. epidermidis and K.
2
pneumonia (C and D) [136]
Figure 2-22 Antibacterial activity of controlled slides and Ag-TiO 84
2
prepared by sol-gel/laser route and furnace sintering route
against E. coli under UV light irradiation using the drop test
method [126].
Figure 3-1 Experimental set-up to generate nanoparticles in ice 96
(frozen deionised water) using a picosecond laser;  =
1064 nm, f = 200 kHz,  = 10 ps, and v = 250 mm/s.
Figure 3-2 (a) Absorption spectra of Ag-TiO colloidal nanoparticles 100
2
generated in frozen deionised water (ice) and unfrozen
deionised water using a picosecond laser;  = 1064 nm, f =
200 kHz, v = 250 mm/s,  = 10 ps, spot size = 125 µm,
E = 42-43.79 µJ and F = 0.342-0.357 J/cm2. (b) The
pulse laser
bottles of Ag-TiO nanoparticles generated in ice (right-
2
hand bottle) and deionised water (left-hand bottle). (c)
Indirect and (d) direct band gaps of the Ag-TiO
2
nanoparticles generated in ice and deionised water.
Figure 3-3 TEM images of Ag-TiO nanoparticles produced in ice 101
2
using the picosecond laser (a,c,d,e). A histogram and
lognormal size distribution of produced Ag-TiO
2
nanoparticles (b).
Figure 3-4 HAADF and EDS images (line profile) of the Ag-TiO 102
2
nanoparticles generated in frozen deionised water using a
picosecond laser.
Figure 3-5 EDS image of Ag-TiO nanoparticles that shows their 103
2
chemical components, which include C, Cu, Ag, Ti and O.
Both Cu and C are from the grid and grid coating
respectively. The presence of high amounts of Ag, Ti, and
O indicates the formation of Ag-TiO nanoparticles in the
2
solution.
Figure 3-6 (a) Absorption spectra of TiO colloidal nanoparticles 104
2
generated in both deionised and frozen deionised water
(ice) using a picosecond laser;  = 1064 nm, f = 200 kHz, v
= 250 mm/s,  = 10 ps, spot size = 125 µm, E = 42-
pulse
43.79 µJ, F = 0.342-0.357 J/cm2 and t= 10 min. (b) The
laser
real bottles of the TiO nanoparticles generated in both
2
media. (c) Indirect and (d) Direct band gaps of the TiO
2
nanoparticles generated in ice and deionised water.
Figure 3-7 (a) Number of surviving E. coli bacteria as a function of 105
concentrations of the Ag-TiO and Ag nanoparticles. (b)
2
Histogram of relative the antibacterial activity of Ag-TiO ,
2
TiO and Ag nanoparticles at 12.5 µg/ml concentration. The
2
test were done a day after preparation of nanoparticles.
(Note; the control value, i.e. no nanoparticles in Figure (b)
is 1). They were tested under standard room light.
Figure 4-1 Experimental set-up for generation of Ag-TiO 114
2
8
nanoparticles in deionised water in an ultrasonic cleaning
bath.
Figure 4-2 The absorption spectra of (a) Ag, TiO and (b) Ag-TiO 118
2 2
colloidal nanoparticles generated in deionised water in an
ultrasonic tank and without ultrasonic tank by picosecond
laser ablation in deionised water (P= 9.12 W, f= 200 kHz
and v= 250 mm/s). In the Ag-TiO suspension produced in
2
the ultrasonic tank, the amount of Ag and TiO
2
nanoparticles were 0.5 mg and 0.6 mg respectively. The
ablation time for Ag, TiO and Ag-TiO with ultrasonic
2 2
waves was 16 min, and for Ag-TiO without ultrasonic
2
waves it was 10 min.
Figure 4-3 (a-d) TEM images of Ag-TiO nanoparticles generated in 119
2
deionised water by the picosecond laser (P = 9.12 W, f =
200 kHz, v = 250 mm/s and t = 16 min.). The production
process was carried out in a tank of ultrasonic cleaner with
a frequency 49 kHz. The ablation rate of Ag-TiO
2
nanoparticles was 0.068 mg/min with a Ag:TiO ratio of
2
1:1.2. Figure 3-e is the lognormal size distribution of Ag-
TiO nanoparticles.
2
Figure 4-4 High-Angle Annular Dark-Field Microscope (HAADF) 120
images of the Ag-TiO nanoparticles.
2
Figure 4-5 EDS - Line profile images of the Ag-TiO nanoparticles 121
2
synthesised by picosecond laser in deionised water
supporting ultrasound waves in an ultrasonic cleaner.
Figure 4-6 X-Ray Diffraction (XRD) spectrum of Ag-TiO nanoparticles 122
2
produced by picosecond laser in deionised water in
ultrasonic vibration.
Figure 4-7 TEM images of Ag-TiO nanoparticles produced in 122
2
deionised water using picosecond laser without using
ultrasonic waves. (Wavelength 1064 nm, power 9.12 W,
frequency 200 kHz and scan speed 250 mm/s and t = 10
min).
Figure 4-8: (a and b) TEM images of TiO nanoparticles generated in 123
2
deionised water in an ultrasonic cleaner tank by
picosecond laser (P = 9.12 W, f = 200 kHz, v = 250 mm/s
and t = 15 min.). The quantity of TiO nanoparticles
2
generated in the suspension is 0.8 mg and the
concentration is 53.3 µg/ml. The ablation rate of TiO NPs
2
is 0.0533 mg/min. (0.8 mg/15 min). (c) Histogram of the
size distribution of TiO nanoparticles.
2
Figure 4-9 (a and b) TEM images of Ag nanoparticles generated by 124
picosecond laser in deionised water without ultrasonic
vibration. Laser parameters; P = 9.12 W, f = 200 kHz, v =
250 mm/s. (c) Histogram of the size distribution of Ag
nanoparticles.
Figure 4-10 Antibacterial activity of Ag-TiO nanoparticles in 124
2
comparison with control sample. Equal amount of E. coli
were cultured with (Ag-TiO (ultrasonic wave based
2
generation), Ag and TiO ) nanoparticles or without (control)
2
nanoparticles in LB broth for 6 hours and 10 µl of the broth
culture was plated on to LB agar plate for colony formation
after overnight incubation at 37 C overnight. The number
9
of E. coli colonies represents the survived E. coli after
culturing with or without nanoparticles which negatively
correlate to the antibacterial effect of the nanoparticles.
Figure 4-11 Relationship between the number of surviving E. coli 125
bacteria as a function of the concentration of Ag-TiO (US)
2
(ultrasonic) and Ag nanoparticles generated by picosecond
laser in deionised water with ultrasonic wave assisted. The
antibacterial test was carried out under normal light.
Figure 4-12 Image of plasma plume and nanoparticles dispersing in 127
deionised water during picosecond laser ablation of a
target (without using ultrasonic waves). The photo is taken
after recording the ablation process by a normal camera.
Figure 5-1 Experimental set-up for generation of nanoparticles in 137
deionised water by picosecond laser.
Figure 5-2 Reflectivity of the Ti/Ag alloy plate. 139
Figure 5-3 XRD of Ti/Ag alloy bulk sample. 140
Figure 5-4 XRF of the Ag/Ti alloy. 140
Figure 5-5 The absorption spectra of the Ag-TiO compound 142
2
nanoparticles produced by picosecond laser in deionised
water (a). Indirect band gap energy of the Ag-TiO
2
compound nanoparticles (b).
Figure 5-6 TEM images of the Ag-TiO compound nanoparticles 143
2
generated by picosecond laser in deionised water (a,b,c
and d). Histogram of the nanoparticles’ lognormal size
distribution (e). The ablation rate of the Ag-TiO
2
nanoparticles is 0.13050.029 mg/min.
Figure 5-7 (a,b,c and d) HAADF-STEM and EDS images of the Ag- 144
TiO compound nanoparticles.
2
Figure 5-8 Line profile spectrum (a) and EDS images (b) of the Ag- 145
TiO compound nanoparticles.
2
Figure 5-9 The atomic percentage (at.%) ratio of Ag:Ti:O chemical 146
elements of a spectrum of some of the nanoparticles (or
points).
Figure 5-10 XRD image of the Ag-TiO compound nanoparticles. 146
2
Figure 5-11 XPS images of the Ag-TiO compound nanoparticle. Peak- 148
2
fitting spectra at high resolution of Ag 3d (q), Ti 2p spectra
(b) and O 1s spectra (c) of the Ag-TiO compound
2
nanoparticles.
Figure 5-12 Sedimentation of Ag-TiO compound nanoparticles (a), and 151
2
Ag nanoparticles (b) during time. (c) The average sizes of
the nanoparticles as a function of time. The photographs
show the bottles which contain the colloidal nanoparticles.
Figure 5-13 The absorption spectra of Ag (a) and Ag-TiO (b) 152
2
nanoparticles on the day of preparation as well as after 15
and 30 days.
Figure 5-14 Antibacterial activity of the Ag and Ag-TiO compound 154
2
nanoparticles at 20 µg/ml (a) and 25 µg/ml (b) compared
with control sample (c) under standard room light and dark
conditions after one day of generation.
Figure 5-15 Number of survived E. coli colonies as a function of 155
incubation time for Ag-TiO , Ag and control under standard
2
room light. The concentration of nanoparticles was 20
µg/ml.
10