Surface Analysis: Application for Biomaterials

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1 Surface Analysis: Application for Biomaterials S. Kaciulis, A. Mezzi, P. Soltani* Area della Ricerca Roma Monterotondo, Italy * PhD student at the University of Rome «Tor Vergata»

2 IMPORTANCE of the SURFACE All materials interact with external surrounding through their surface. Chemical reactions (catalysis, corrosion, gas sensing, etc.) - the surface atoms are defining the total reactivity. The surface atoms (either of the material or adsorbed ones) control the friction and wear mechanisms. 2D and 1D microelectronics only the surface is operating. Biocompatible materials the surface is the most important part for interaction with human body. Bulk ~ at. Surface ~ at. Surface / Bulk ~ 10-8

3 ESCA = XPS + AES (Auger) Physical principle: exciting photon excited electron B.E. E f K.E. e - e - hν E 3 E 2 E 1 XPS BE = hn KE - WF AES KE 123 = E 1 E 2 E * 3

4 XPS: X-ray Photoelectron Spectroscopy Registered signal: I = f (KE) e-gun BE = hν KE - WF hν: Al Kα = ev Mg Kα = ev Obtained spectrum: I = f (BE)

5 Analysis Depth Mean free path of the electrons λ: I ~ N(z)exp (-z/λ)dz Information depth 3λ Contamination by residual gases: at 10-6 mbar 1 monolayer/sec The pear of SEM EDS N.B. the lateral resolution of EDS is low! UHV

6 Amphiphilic Cyclodextrins: linkage to metal NPs and immobilization on solid substrate Noble metal NPs Magnetic NPs Cancer Diagnosis Biomedical applications Therapy - Optical biosensors - Electrical nanosensors - Electrochemical biosensors - Nanowire biosensors - Viral nanosensors - Nanoshell biosensors - Nanotube-based biosensors Aim of this study Au NPs linked with amphiphilic cyclodextrins for the biosensing, diagnostics and targeted drug delivery (photothermal and photodynamic therapy).

7 Heptakis (2-amino-oligo (ethylene glycol)-6-deoxy-6-hexyl-thio): CD (SC 6 NH 2 ) C O N S H H O S R O O O 7 O n N H + 3 R = C 6 H 13 n = 1-2 SC6NH + 3

8 INTERACTION of Au NP with CD Bonding with thiol or amino groups?? Au Substrate: Si and glass Au/SC6NH2 Au/SC16NH2 XPS chemical bonding FE-SEM - morphology

9 XPS results S 2p Au/SC6NH2 Au-S bond S unbonded S 2p3/ Au/SC16NH2 Beulen et al., Langmuir, Vol. 14, No. 22, Au S No interaction Au thiol!

XPS results N1 N2 N 1s N1 N2 Au NH2 Peak BE(eV) Bond N1 400.

10 XPS results N1 N2 N 1s N1 N2 Au NH2 Peak BE(eV) Bond N amine group N metalcoordinated amine Au/SC6NH2 N3 Au/SC16NH2 N ammonium

11 XPS results Au+SC6NH2 Au 4f 7/2 Au 4f 5/2 Au 4f Au 4f 7/2 assignment: 84.0 ev - Au(0) 85.2 ev - Au(+1) Au(0)/Au(+1) ev 85.2 ev Au Au+SC16NH2 Au amine bonding was revealed by XPS A. Mazzaglia et al., J. Phys. Chem. C 113 (2009)

linear, semi-crystalline polysaccharide, obtained from natural chitin, biocompatible and

12 Composite films: chitosan with Ag NPs in mesoporous silicate SBA-15 TEM image: Ag NPs within tubular mesopores of SBA-15 FE-SEM image: SBA-15 with Ag NPS Matrix - thin film of chitosan: linear, semi-crystalline polysaccharide, obtained from natural chitin, biocompatible and biodegradable, has antimicrobial and hydrating properties, application: antimicrobial wound dressing

13 XPS: C 1s spectra of composite films a) chitosan b) chitosan-sba-ag15% C2 I (cps) C1 C3 I (cps) C1 C3 C4 C2 C BE (ev) BE (ev) Component C1 C2 C3 C4 Bond C C, C H C N O C O N C = O Relative increase of C2 and C3 increased amount of carbon bonds with silicate in particles of SBA-15.

14 XPS: Ag 3d spectra of composite films a) Ag 3d Ag 3d5/ d 5/2 A 3d 5/2 B 3d 3/2 A Ag 3d5/3 I (cps) d 3/2 B I (cps) ev BE (ev) BE (ev) As prepared sample: differential charging of NPs After soaking in water: no charging Size-shift of Ag 3d: modified Auger parameter α = ev metallic Ag. ΔBE = (metallic Ag) = 0.4 ev. from size-shift diameter of NPs is about 6 nm. V. Ambrogi et al., J. Mater. Chem. B 2 (2014) 6054.

Ceramic Coatings for Orthopaedic Implants Possible improvements of TJA implants - replacement of plastic component with ceramic or metallic materials (metal-on-metal, ceramic-on-ceramic and

Innovative deposition technique PPD, which was recently developed for the preparation of HA, ZrO 2 and YSZ films.

15 Ceramic Coatings for Orthopaedic Implants Possible improvements of TJA implants - replacement of plastic component with ceramic or metallic materials (metal-on-metal, ceramic-on-ceramic and metal-onceramic couplings), the surface modification of metallic and plastic components, replacement of brittle monolithic ceramics with ceramic films. Innovative deposition technique PPD, which was recently developed for the preparation of HA, ZrO 2 and YSZ films. In comparison with plasma spray (most widespread technology), it allows to deposit thinner coatings: only up to few microns against µm. Lower residual stresses, higher homogeneity, crystalline structure, improved adhesion, etc. Prepared and investigated materials: films of HA and HA with magnetite, YSZ and alumina-zirconia coatings.

Substrates: p-si wafers and Ti disks for HA and Mag-HA; medical grade UHMWPE and Ti for hard coatings.

16 Pulsed Plasma Deposition Targets: HA sintered at 1,200 C; HA-magnetite of 90 : 10 wt%, tetragonal YSZ with 3% of Y 2 O 3 sintered at 1,500 C; composite Al 2 O 3 ZrO 2 of 75 : 25 wt%. Substrates: p-si wafers and Ti disks for HA and Mag-HA; medical grade UHMWPE and Ti for hard coatings. Gen III Advanced Electron Gun (Organic Spintronics, Bologna, Italy) Electron pulse of 100 ns, f = 6 Hz, E = 10 J/cm 2, density = 108 W/cm 2.

17 HA films Sputtered film (depth 50 nm) Carbon contamination removed at d 5 nm. Stoichiometric HA with Ca : P = Depth profile (total thickness of about 300 nm)

HA magnetic films Thickness: from 280 up to 3,100 nm. Grain size: 50 400 nm. R A : 30-100 nm, increased with d.

18 HA magnetic films Thickness: from 280 up to 3,100 nm. Grain size: nm. R A : nm, increased with d. Higher R A promotes bacterial adhesion. XPS depth profile constant composition. Fe 2p3 A Fe2O3 Fe 2p3 B magnetite Fe3O4 ratio Fe B/ Fe A 0.33

Hard coatings: YSZ (3% Y 2 O 3 ) and ZrO 2 -Al 2 O 3 films Zr 3d 5/2 = 182.

No changes after annealing. Constant Y : Zr 0.05. Zr 3d 5/2 = 182.

19 Hard coatings: YSZ (3% Y 2 O 3 ) and ZrO 2 -Al 2 O 3 films Zr 3d 5/2 = ev and Y 3d 5/2 = 157 ev confirm the presence of ZrO 2 and Y 2 O 3. No changes after annealing. Constant Y : Zr Zr 3d 5/2 = ev and Al 2p 74 ev confirm the presence of ZrO 2 and Al 2 O 3. No changes after annealing. Constant Zr : Al = 0.15.

20 CONCLUSIONS Homogeneous nanostructured films of HA and magnetic HA were prepared by using innovative PPD technique. After annealing in air, these films became crystalline and almost stoichiometric, with only a small fraction of CaO. The doping with about 3 at% of magnetite was constant through the films thickness. The same technique was successfully employed for the growth of hard coatings: cubic YSZ and composite ZrO 2 -Al 2 O 3 films. Both the coatings were nanostructured, uniform in depth and thermally stable. S. Kaciulis, et al., Surf. Interface Anal. 48 (2016) 616. A. Gambardella, et al., Mat. Sci. Eng. C, 62 (2016) 444. M. Boi, et al., RSC Adv. 5 (2015)

21 Carbon allotropes sp 3 - DIAMOND CARBON ALLOTROPES sp 2 GRAPHITE sp 2 & sp 3 DLC, ac, ac:h 2D sp 2 SWCNT, GRAPHENE Electronic configuration: fourfold sp 3 (diamond), threefold sp 2 (graphite), linear sp 1 ; tetrahedral sp 3 configuration - σ bonds; trigonal sp 2 configuration - π bonds. π-type bonds determine the electronic properties and optical gap, σ-type bonds define the mechanical hardness (diamond-likeness). sp 3 sp 2

22 Definition of the D parameter C KVV spectrum: D parameter - the distance between the most positive maximum and most negative minimum of the first derivative. Assessed peak-to-peak width of C KVV spectrum enables to determine sp 2 /sp 3 ratio in carbon allotropes by using linear calibration from diamond to graphite. J.C. Lascovich et al., Appl. Surf. Sci ; 47, 17. A. Mezzi, S. Kaciulis, Surf. Interface Anal ; 42, 1082.

23 Results: C KVV spectra Source Sample D, ev hν Graphite ref Diamond ref Graphene/Si 15.0 Graphene/Cu 14.2 Graphene/Cu, T = 400 C sp 2, % Graphene/Cu, cooled LN e Graphite 21.0 Diamond 14.2 Graphene/Si 20.9 Graphene/Cu C KVV spectra of graphene samples S. Kaciulis, et al., Surf. Interface Anal. 46 (2014) 966. S. Kaciulis et al., Thin Solid Films 581 (2015) 80. N. Yan et al., Composites Sci. Technol. 102 (2014) 74.

24 ACKNOWLEDGMENTS Dr. A. Mazzaglia, ISMN CNR, Messina. Dr. D.M. Trucchi, ISM CNR, Rome. Dr. M. Bianchi, Istituto Ortopedico Rizzoli, Bologna. Prof. V. Ambrogi, University of Perugia.

X-ray Photoelectron Spectroscopy

X-ray Photoelectron Spectroscopy X-ray photoelectron spectroscopy (XPS) is a non-destructive technique used to analyze the elemental compositions, chemical and electronic states of materials. XPS has a