Surface Antimicrobial Effects of Zr61al7.5Ni10cu17.5Si4 Thin Film

Fooyin J Health Sci 2010;2(1):12−20

ORIGINAL ARTICLE

Surface Antimicrobial Effects of Zr61Al7.5Ni10Cu17.5Si4 Thin Film Metallic Glasses on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Candida albicans

Pai-Tsung Chiang1,2*, Guo-Ju Chen1, Sheng-Rui Jian1, Yung-Hui Shih1, Jason Shian-Ching Jang3, Chung-Hsu Lai4

1Department of Materials Science and Engineering, I-Shou University, Kaohsiung, Taiwan 2Department of Plastic Surgery, Fooyin University Hospital, Pingtung, Taiwan 3Department of Mechanical Engineering, Institute of Materials Science and Engineering, National Central University, Chung-Li, Taiwan 4Department of Infectious Disease, I-Shou University, Kaohsiung, Taiwan

Received: November 11, 2009 Revised: January 21, 2010 Accepted: February 8, 2010

Zr61Al7.5Ni10Cu17.5Si4 (ZrAlNiCuSi) thin film metallic glasses (TFMGs) can modify the surface of 304 stainless steel, and they are widely used in health care systems. We investigated modified surfaces with ZrAlNiCuSi TFMGs and their antimicrobial effects on those five microbes which are the most common nosocomial infection pathogens. The transfor- mation of ZrAlNiCuSi bulk metallic glass into TFMG was achieved by sputtering onto stainless steel. Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Candida albicans were then isolated. The microbes were sampled on ZrAlNiCuSi TFMGs, and this was compared with stainless steel plates. After microbe− material interaction under humidity at room temperature for 3 hours, the specimens were attached to a Mueller- Hinton agar plate (Gibco, Middleton, WI, USA) and incubated at 37.0ºC for 24, 48 and 96 hours. The areas of microbe growth were recorded by serial subtraction photography and then assessed using Image-Pro Plus software (Media Cybernetics, Bethesda, MD, USA). ZrAlNiCuSi TFMGs presented an amorphous rough surface and exhibited hydrophobic properties. ZrAlNiCuSi TFMGs suppressed E. coli growth on Mueller-Hinton plates for 96 hours, and there was no E. coli growth on blood agar plate enriched media and eosin-methylene blue agar selective media after 96 hours of incubation. The five microbes tested on ZrAlNiCuSi TFMGs showed a decreased growth curve after 24 hours. After 24 hours, P. aeruginosa showed a slow growth curve and A. baumannii had a sharp growth curve with TFMG interaction. ZrAlNiCuSi TFMGs prolonged the lag phase of the microbes’ growth curve in S. aureus and C. albicans for 48 hours. ZrAlNiCuSi TFMGs were able to modify the surface of stainless steel, which was very hard and was found to have scratch adhesion abilities and smooth surface effects against five different microbes for at least 24 hours. This is the first description of microbe interactions with zirconium-based TFMGs. Further studies to investigate the mechanism of antimicrobial effects on ZrAlNiCuSi TFMGs are now required.

Key Words: antimicrobial effects; surface; thin film metallic glass

*Corresponding author. Department of Plastic Surgery, Fooyin University Hospital, No. 5, Zhongshan Road, Donggang Town, Pingtung County 928, Taiwan. E-mail: [email protected]

Introduction biofilms and the increasing resistance of microbes to antibiotics. Fortunately, nosocomial infection control In health care, the most common pathogens caus- can be improved by inhibiting the growth of fungi, ing outbreaks of infection are Escherichia coli, bacteria and viruses in the environment of health Staphylococcus aureus, Pseudomonas aeruginosa, care systems.11,14,15 Microbial growth and biofilm Acinetobacter baumannii, and Candida albicans.1−3 formation are characterized by their colonized en- E. coli is the primary organism isolated from vari- vironmental conditions. Environmental factors in- ous clinical specimens. It adapts to environmental clude nutrient sources and local conditions such as challenges with exceptional alacrity.4 The preva- pH, osmolarity, temperature, oxygen, hydrodynamic lence of nasal S. aureus carriage is approximately conditions, and surface properties. The surface of 20−25% but varies among different populations, and an object could affect planktonic organisms, and is influenced by age, underlying illness, race, certain therefore, surface properties might be involved in behaviors, and the environment in which the person antimicrobial mechanisms.3,16,17 lives or works.5 The wearing of a clean gown and Stainless steel can be found in health care in gloves for any physical contact with a patient or their door handles, push plates and devices such as sur- environment is necessary to prevent an outbreak of gical instruments.18−20 Sputtering hard smooth thin infection; nonetheless, new cases of methicillin- films onto stainless steel can change surface con- resistant Staphylococcus aureus continue to arise.6 ditions. Good adhesion between microbes and the The outbreak of infection caused by Pseudo- host’s or material’s surface is the initial step in inoc- monas respiratory colonization in immunocompro- ulation to induce nosocomial infection, and bacterial mised patients is a nosocomial acquisition, and adhesion to solid surfaces depends on the interac- probably occurs by transmission through contami- tion between the adhesion quantity of bacteria and nated nebulizer devices.7 The best approach to surface quality of the material.20−24 Surface modi- control P. aeruginosa ventilator-associated pneumo- fication using thin films onto 304 stainless steel nia is to prevent the endogenous and exogenous door contactors might be an effective way to control transmission of P. aeruginosa in colonization of the infection.18−20,23,25,26 lungs in mechanically ventilated patients.8 Thin film metallic glasses (TFMGs) can modify Although no definitive virulence factors are the surface of stainless steel. Metallic glass is a new known, A. baumannii is relatively common in both category within metallic materials. There has been hospitalized patients and the hospital environment.9 extensive research in metallic glasses over the past Candida species are the fourth most common cause 20 years. After a breakthrough in the early 1990s, of nosocomial bloodstream infection and are involved many systems such as lanthanum-, magnesium- in 8% of disseminated microbial infections.10 Thus, and zirconium (Zr)-based bulk metallic glasses new modifications are required to reduce the number (BMGs) were developed. In addition to the metal- of microbes on surfaces in health care institutions lic glasses in bulk form, metallic glasses have re- and minimize the acquisition of infections. cently been extended to the thin or thick film area; Antibiotics are usually used to control infections; this is an attempt to find applications in micro- this occurs because of their bactericidal, bacterio- electromechanical systems. For such applications, static or mycostatic effects. However, many pan-drug the amorphous alloys sometimes need to be fabri- resistant microbes have been observed.11−13 Noso- cated via sputtering or other thin film processes. comial infections in intensive care units have steadily The as-deposited TFMGs usually exhibit a uniform increased over the past several decades. Health care composition without microsegregation, thus avoid- is a challenge when endogenous flora are combined ing possible local crystallization during the fabri- 27 with reactivation of latent infectious agents and ex- cation process. Zr61Al7.5Ni10Cu17.5Si4 (ZrAlNiCuSi) ogenous environmental microbes in outbreaks noso- TFMGs can modify the surface of stainless steel.28 comial infections. Nosocomial infections are also Zr-based BMGs are recognized as one of the frequently caused by transmission of pathogens in most promising structural materials because of their the health care environment from instruments or high tensile strength, high elastic modulus, and high equipment, and by direct hand-to-hand contact of corrosion resistance. In addition, Zr-based BMGs health care providers with patients. In intensive care possess a high glass-forming ability, relatively good units, mechanical ventilation is applied after placing thermal stability, an extremely wide supercooled a cuffed polymer endotracheal tube. This tube is liquid region (exceeding 100 K), homogeneous dis- a continuous source of microbial colonization of tribution of multiple elements, and ease of fabri- the lower respiratory tract, ultimately resulting in cation.24,29−31 Zr-based TFMGs exhibit inherent ventilator-related pneumonia. Treatment of infec- optimum properties and can be applied to modify tions associated with medical devices is often frus- the surface condition of stainless steel.28 The direct trated by the inability of antibiotics to penetrate current (DC) sputtering method is a simple method 14 P.T. Chiang et al of changing the surface condition of stainless steel, Technologies Inc., Tainan, Taiwan) for the substrate and is used to transform ZrAlNiCuSi BMGs into and ZrAlNiCuSi TFMGs. ZrAlNiCuSi TFMGs, which are coated onto the stainless steel substrate. Previous reports have tended Mechanical testing to focus on Zr-based BMGs or TFMGs for manufactur- ing or processing methods, or have examined the The adhesion capability between the films and the microstructure properties or mechanical properties 304 stainless steel substrate was evaluated using a of materials.4,27−33 However, there are few reports on Teer ST 2330 scratch tester (Teer Coatings Ltd., biologic use with regard to microbes against other Worcestershire, UK), under a maximum load of 3 kg. materials.17,18 The present study looks at microbe Nano-indentation was applied to measure the hard- interactions with Zr-based TFMGs and the bare 304 ness of the ZrAlNiCuSi TFMG produced at a sputtering stainless steel substrate. We examined the surface power of 35 W. antimicrobial properties of ZrAlNiCuSi TFMGs for E. coli, S. aureus, P. aeruginosa, A. baumannii and Antimicrobial evaluation C. albicans. The optimal microstructure condition of amorphous ZrAlNiCuSi TFMG at a sputtering power of 35 W was Materials and Methods selected to investigate antimicrobial effects. E. coli (ATCC 25922), S. aureus (ATCC 25923), P. aeruginosa Material preparation (ATCC 27853), A. baumannii (clinical isolate) and C. albicans (clinical isolate) were used to evaluate The as-prepared ZrAlNiCuSi BMG was selected as the bactericidal, bacteriostatic or mycostatic ef- the target material for the sputtering process. The fect of ZrAlNiCuSi TFMGs and 304 stainless steel ZrAlNiCuSi thin films were coated onto a 304 stain- materials. A volume of 0.01 mL per drop (1.5 × 106 less steel substrate by means of a vacuum DC MDX colony-forming unit/mL) of the strains was tested 1000 sputtering system (MeiVac Inc., San Jose, CA, on ZrAlNiCuSi TFMG. A 304 stainless steel plate was USA). Sputtering involved firing ions toward a Zr- used as the control plate. AlNiCuSi BMG target to displace atoms, which were After microbe−material interactions for 3 hours then deposited on a 304 stainless steel substrate to on the aseptic bench at room temperature, the spec- form a ZrAlNiCuSi thin film; a bare 304 stainless steel imens were attached onto Mueller-Hinton agar substrate was used as a comparison. The operating (Gibco, Middleton, WI, USA) and incubated individ- conditions of the DC sputtering system were set at ually at 37.0ºC for 24, 48 and 96 hours. The areas of a base pressure of 6 × 10−6 torr, a working pressure microbe growth were recorded at each incubation of 4 millitorr, argon (Ar) flow of 5.4 standard cm3, period by using subtraction photography, and anti- sputtering time of 30 minutes and varying sputtering microbial effects were then assessed using Image- powers of 15 W, 20 W, 25 W, 30 W, 35 W and 40 W. The Pro Plus software (Media Cybernetics, Bethesda, MD, composition distributions of the Zr-based thin films USA). Some tissues obtained from the surface of were analyzed by the HORIBA energy dispersive spec- each infected plate were transferred to blood agar trum (HORIBA Instruments Inc., Ann Arbor, MI, USA). plates and eosin-methylene blue agar for semi- The alpha-step profilometer (Zygo Corp., Middle- quantitative colony counts. The organisms were field, CT, USA) was conducted to measure the thick- identified using standard biochemical reactions. ness of the ZrAlNiCuSi thin films, which had been fabricated with different sputtering powers. Results Microstructure evaluation Material composition The microstructure of the ZrAlNiCuSi thin films was examined by glancing incidence X-ray diffraction The composition of the as-sputtered ZrAlNiCuSi thin (X’Pert Pro; PANalytical, The Netherlands) and by films was similar to the ZrAlNiCuSi BMG as shown FEI Tecnai G2 T20 transmission electron microscopy by energy dispersive spectrum (Table 1). This non- (TEM) (FEI, Hillsboro, OR, USA) operated at 200 kV. homogenous distribution was only found in the low The surface roughness was analyzed by a field emis- sputtering power range of 15 W. The thickness of the sion scanning electron microscope (Hitachi S-4700; ZrAlNiCuSi thin films was related to sputtering Hitachi, Tokyo, Japan) and atomic force micros- power and exhibited a reasonably linear relation- copy (P7LS; NT-MDT Co., Moscow, Russia). At the ship (Figure 1). A 550-nm thickness of ZrAlNiCuSi thin same time, the water contact angle was examined film could be fabricated within 30 minutes at a by a contact angle meter (CAM 100; Creating Nano sputtering power of 35 W. Antimicrobial effects of Zr-based TFMG 15

Table 1 Compositions of the target material and sput- (220) tered thin films analyzed by the energy disper- (200) sive spectrum method (111) Composition (atomic %) 40 W Power (W) Zr Al Ni Cu Si 35 W 15 44.97 7.68 27.63 15.88 3.84 30 W 20 56.27 6.86 16.68 17.85 2.34 25 W 25 56.89 7.58 14.77 17.66 3.10 30 58.24 6.77 14.56 18.35 2.07 20 W

35 57.37 6.88 14.79 18.19 2.76 Intensity (arbitrary unit) 15 W 40 56.14 7.37 15.08 18.61 2.80 304 stainless steel Target 61.00 7.50 10.00 17.50 4.00

600 3 20 30 40 50 60 70 80 2θ(°) 500 Roughness (nm, Figure 2 X-ray diffraction patterns of the Zr61Al7.5Ni10Cu17.5 400 2 Si4 thin films prepared by different sputtering powers.

300

200 1 Thickness (nm, ) Thickness (nm, ) 100

0 0 15 20 25 30 35 40 Power (W)

Figure 1 Thickness () and average surface roughness () of the Zr61Al7.5Ni10Cu17.5Si4 thin films as a function of sputtering power.

Microstructure observations

X-ray diffraction revealed a typical blunt, arc-shaped amorphous feature under less than a 30º X-ray in- cident angle for all of the ZrAlNiCuSi thin films pro- Figure 3 Transmission electron microscopy bright-field duced at different sputtering powers (Figure 2). image of the zirconium-based alloy thin film. The selected Because these films were so thin especially those fab- area diffraction pattern revealed atomic clusters with a ricated by the low sputtering power, several sharp nano-scaled amorphous microstructure of Zr61Al7.5Ni10 peaks at the plane indices (111), (200) and (220) Cu17.5Si4 thin film metallic glasses. caused by the crystalline structure of the 304 stainless steel (substrate) were observed in the X-ray the water contact angle on 304 stainless steel sub- diffraction pattern. A TEM bright-field image of the strates was 46.2º, and on ZrAlNiCuSi TFMG it dis- Zr-based TFMG revealed a typical amorphous micro- played a near-perpendicular angle of 87.9º with structure with a halo ring in the selected area dif- hydrophobic properties (Figure 4). fraction pattern (Figure 3). Mechanical properties of the materials Surface physical properties Results of the scratch test showed that the adhe- The surface roughness of the 304 stainless steel sion capability increased with sputtering power. substrate was 7.50 nm by atomic force microscopy. A saturated value of 70 N occurred with ZrAlNiCuSi There was a trend for a decrease in surface rough- TFMGs that had been fabricated with a sputtering ness with increasing sputtering power (Figure 1). power of 35 W. In addition, the hardness of ZrAlNi- An average surface roughness of approximately 1 nm CuSi TFMGs prepared at 35 W was 5.83 ± 0.41 GPa and was obtained for ZrAlNiCuSi TFMGs prepared with 6.01 ± 0.17 GPa under loads of 2500 μN and 3000 μN, a sputtering power of more than 25 W. Additionally, respectively. 16 P.T. Chiang et al

A B

Figure 4 Water contact angle on Zr61Al7.5Ni10Cu17.5Si4 thin film metallic glasses shows a perpendicular angle of (A) 87.9º with hydrophobic properties and (B) 46.2º on a 304 stainless steel substrate.

A B C

D E Figure 5 Bacterial incubation test for Zr61Al7.5Ni10 Cu17.5Si4 thin film metallic glasses (left side) and 304 stainless steel (right side) using Escherichia coli on Mueller-Hinton plates for (A) 24 hours, (B) 48 hours, and (C) 96 hours. Microbes were identified using blood agar plate (right) and eosin- methylene blue agar (left) media for 24 hours of incubation by streaking tissue from the surface of (D) 304 stainless steel and (E) Zr61Al7.5Ni10Cu17.5Si4 thin film metallic glasses.

Antimicrobial effects The growth areas of the microbes were assessed at different times of 0, 24, 48 and 96 hours and were Figure 5 shows the antibacterial activity of subjected to dividing by the testing sample area ZrAlNiCuSi TFMG on E. coli for 96 hours. S. aureus, to generate a ratio as multiple dots. The semi- P. aeruginosa, A. baumannii and C. albicans on quantitative colony counts were constructed as a ZrAlNiCuSi TFMGs exhibited a decreased growth curve with multiple dots for each microbe’s interac- curve with a bacteriostatic or mycostatic effect tion with one material sample. A concave growth for 24 hours. ZrAlNiCuSi TFMGs prolonged the lag curve in culture initially showed a decrease, but then phase with bacteriostatic or mycostatic effects on an increase in slope occurred. E. coli on ZrAlNiCuSi S. aureus and C. albicans for 48 hours. P. aerugi- TFMG exhibited a sustained decrease in growth with nosa on ZrAlNiCuSi TFMG showed a slow increase better activity after 96 hours of incubation (Figure 7). in growth with greater inhibition effects for a period of between 24 hours and 96 hours compared with the 304 stainless steel substrate. Moreover, Discussion A. baumannii on Zr-based TFMG demonstrated a rapid increase in growth in the following 24 hours The relative optimum film deposition rate of DC (Figures 6 and 7). sputtering depends on the sputtering potential and Antimicrobial effects of Zr-based TFMG 17

A 14 Thin film coating 304 stainless steel substrate 12 B

C 8

D 6

4 Microbes to sample area ratio sample area Microbes to Figure 6 Serial photography at 24 hours, 48 hours and 96 hours for Zr61Al7.5Ni10Cu17.5Si4 thin film metallic 2 glasses (left) and 304 stainless steel (right) using (A) Staphylococcus aureus, (B) Pseudomonas aeruginosa, 0 (C) Acinetobacter baumannii and (D) Candida albicans, using the Mueller-Hinton plate incubation test. 010 2030405060708090100 current variables. In general, the deposition rate is Time (hr) proportional to the power consumed or to the square of the current density, and it is inversely depend- Figure 7 Microbes to sample area ratio shown as a ent on the electrode spacing.34 The optimal power function of incubation time for different microbes grow- of DC sputtering for transforming Zr-based BMGs ing on Mueller-Hinton agar plates. Escherichia coli ( ); into TFMGs on substrates is in the range of 35−40 W. Staphylococcus aureus ( ); Pseudomonas aeruginosa (); Acinetobacter baumannii ( ); Candida albicans This may be attributable to a decrease of thermal (). A dashed line indicates Zr61Al7.5Ni10Cu17.5Si4 thin film conductivity due to the increase in deposition metallic glasses and a solid line indicates 304 stainless ≥ thickness at higher sputtering powers of 45W. steel substrate. However, a lower power of ≤ 25W is recommended so that a bare surface or uneven thickness of depo- a 304 stainless steel substrate to achieve a hard- sition can remain.30,32 ness ≥ 5.50 GPa of ZrAlNiCuSi TFMG is an accepta- In our study, X-ray diffraction and TEM exami- ble processing route to modify the surface of the nation showed that ZrAlNiCuSi thin films were fab- substrate. ricated at a sputtering power of 35 W, and were The growth curve in a microbial culture is de- confirmed to have a fully amorphous structure from termined by graphing the number for each sample macroscopic as well as microscopic views. The sur- in sequence for the whole incubation period with a face of ZrAlNiCuSi TFMGs can be constructed into lag phase, exponential growth phase, stationary an extremely smooth profile, approximately 1 nm phase and death phase.1 In our study, besides having in roughness, without any grain boundaries or pre- different lag periods varying from one bacterial pop- ferred orientation of grain growth because of the ulation to another, five different microbes were amorphous structure. Moreover, the flat surface was sampled 0.01 mL per drop on ZrAlNiCuSi TFMGs and also thought to contribute to improvement of its internal control stainless steel materials. Although hydrophobic ability. the physical−chemical characteristics of stainless Donohue et al35 proposed that a 50 N load of steel materials and Zr-based TFMGs were different, scratch adhesion between many thin films on steel is both materials exhibited some antimicrobial effects a critical value for commercial use. A saturated value in the decreased phase of the growth curve in the of a 70 N load of scratch adhesion for ZrAlNiCuSi first 24 hours for the five microbes. Some microbes TFMGs onto steel fabricated at a sputtering power also had an exponential increase under such condi- of 35 W exceeds commercial requirements, and is, tions (Figure 7). We observed that the growth curve therefore, comparable with the scratch adhesion was persistently decreased for 96 hours in E. coli on capability of commercial hard coatings. More over, Zr-based TFMG as shown by the microbe to sample Attar36 suggested that a 4.50 GPa hardness of ceramic area ratio. Therefore, ZrAlNiCuSi TFMGs can increase thin film on steel is the average optimal value for the antimicrobial properties of stainless steel sur- commercial coatings. Therefore, sputtering onto faces for at least 24 hours. 18 P.T. Chiang et al

The interaction between planktonic microor- fabricated within 30 minutes at a sputtering power ganisms and a material’s surface might be a key of 35 W. ZrAlNiCuSi TFMGs prepared at a sputtering mechanism for antimicrobial effects. There are power of more than 25 W present an extremely many antimicrobial mechanisms including material smooth morphology with an average surface rough- chemical ionization, crystallization with a redox re- ness of approximately 1 nm. The hardness (≥ 5.50 GPa) action, material surface roughness, and amorphous and adhesion (70 N load) of the substrate of ZrAl- covalent bonding.3,16,17,37−39 Surface roughness, NiCuSi TFMGs produced at a sputtering power of particularly the nano-scale surface topographic 30 W or 35 W was comparable to commercial ceramic features, is the most important characteristic of a hard coatings. In addition, this amorphous thin film physical−chemical surface to determine the distri- had better hydrophobic properties than the stain- bution of microbes.33,38,40−43 Many bacteria cause dis- less steel substrate. Moreover, as a result of the ex- ease because of acquired virulence factors including tremely smooth surface profile and homogenous fimbriae, capsular polysaccharides, and high sur- composition distribution of ZrAlNiCuSi TFMGs, these face hydrophobicity of certain strains. Uropathogenic amorphous thin films exhibited an antimicrobial ef- E. coli harbors diverse adhesins and curling fibers fect on different microbes including E. coli, S. aureus, that contribute to the pathogenicity in the urinary P. aeruginosa, A. baumannii and C. albicans for at tract or in other tissues.9 least 24 hours. Therefore, treatment with ZrAlNiCuSi In our study, we found that an average surface TFMGs by DC sputtering onto a 304 stainless steel roughness of approximately 1 nm on ZrAlNiCuSi TFMGs substrate is an easy and effective process for re- was different from the surface roughness of the 304 ducing microbe activity. stainless steel substrate (7.50 nm). Additionally, In summary, ZrAlNiCuSi TFMGs coating hospital ZrAlNiCuSi TFMGs obtained a near-perpendicular equipment and fittings showed antimicrobial ef- contact angle of 87.9º with hydrophobic proper- fects and reduced colonization and biofilm forma- ties. ZrAlNiCuSi TFMGs have the exceptional ability tion on surfaces. These effects were maintained for to change the environmental surface and decrease at least 24 hours. Therefore, the use of ZrAlNiCuSi the adherent characteristics of microbes, and ulti- TFMGs for antimicrobial coating of hospital equip- mately reduce the number of stains involved in ment and fittings is beneficial. Further studies are infections. now required to determine the mechanism of these Covalently bonded ZrAlNiCuSi TFMGs have an antimicrobial effects. atomic-scaled cluster, and a very smooth surface in which microorganisms harboring flagellum, fimbriae or hyphae in a planktonic or sessile environment do Acknowledgments not readily adhere to the host body. Previous reports have shown antimicrobial effects of materials with We thank Simon White for checking the English metallic ions kill bacteria by destroying cell walls language, punctuation and spelling. We thank Dr and membranes.22,23,44,45 However, a high concen- Victoria Rose, Dr Hans Liu, C.W. Lee and Alexander tration of metallic ions has toxic activity on bio- J. Boyd for assistance in the literature review. We are logic tissues. Therefore, it is suggested that surface very grateful for the assistance of Ms Hsiu-Fang Lin roughness may play a major role modifying antimi- and the instrument support from the Division of crobial effects in ZrAlNiCuSi TFMGs, but the ioniza- Laboratory Medicine in E-Da Hospital. Thanks are tion of chemical chromium or nickel is widely used also due to the Metal Industrial Research and De- in stainless steel substrates.46−49 velopment Centre, and lastly we would like to say Although amorphous thin films such as poly- thank you for the TEM assistance provided by the mers, synthetics, traditional glass or nano-carbon Micro and Nano Laboratory, Department of Materials are commonly applied on the coatings of hospital Science and Engineering, I-Shou University. equipment and fittings used to alter the adhesive capability of microbes,11,16,17,21,39,41,42,50,51 these coating materials are too soft or brittle to effec- References tively adhere to the substrate. Therefore, the higher hardness and better scratch adhesion capa- 1. Talaro KP, Talaro A. Foundation in Microbiology, 4th edi- bilities of ZrAlNiCuSi TFMGs will make it the first tion. New York: McGraw-Hill, 2002. 2. Anaissie EJ, McGinnis MR, Pfaller MA. Clinical Mycology, choice for hospital medical equipment and fittings 1st edition. Philadelphia: Churchill Livingstone, 2003. in the future. 3. Jass J, Surman S, Walker J. Medical Biofilms Detection, Based on our findings for ZrAlNiCuSi TFMGs pre- Prevention and Control, 1st edition. Chichester: John Wiley pared by DC sputtering at different powers, the & Sons, 2003. 4. Isenberg HD, Vellozzi EM. Nosocomial urinary tract infection conclusions of this study are listed as follows. with a slowly growing fastidious Escherichia coli. J Clin A 550-nm thickness of ZrAlNiCuSi TFMGs can be Microbiol 1988;26:364−5. Antimicrobial effects of Zr-based TFMG 19

5. Perl TM, Golub JE. New approaches to reduce Staphylococcus 24. Gao YL, Shen J, Sun JF, et al. Nanocrystallization of Zr-Ti- aureus nosocomial infection rates: treating S. aureus nasal Cu-Ni-Be bulk metallic glass. Mater Lett 2003;57:2341−7. carriage. Ann Pharmacother 1998;32:S7−16. 25. Ballatori N. Transport of toxic metals by molecular mimicry. 6. Safdar N, Marx J, Meyer NA, et al. Effectiveness of preemptive Environ Health Perspect 2002;110(Suppl 5):689−94. barrier precautions in controlling nosocomial colonization 26. Madison V, Duca J, Bennett F, et al. Binding affinities and and infection by methicillin-resistant Staphylococcus aureus geometries of various metal ligands in peptide deformylase in a burn unit. Am J Infect Control 2006;34:476−83. inhibitors. Biophys Chem 2002;101−2:239−47. 7. Takigawa K, Fujita J, Negayama K, et al. Nosocomial 27. Huang JC, Chu JP, Jang JSC. Recent progress in metallic outbreak of Pseudomonas cepacia respiratory infection in glasses in Taiwan. Intermetallics 2009;17:973−87. immunocompromised patients associated with contaminated 28. Chu CW, Jang JSC, Chen GJ, et al. Characteristic studies on nebulizer devices. Kansenshogaku Zasshi 1993;67:1115−25. the Zr-based metallic glass thin film fabricated by magnetron 8. Berthelot P, Grattard F, Mahul P, et al. Prospective study of sputtering process. Surf Coat Technol 2008;202:5564−6. nosocomial colonization and infection due to Pseudomonas 29. Jang JSC, Lu SC, Chang LJ, et al. Crystallization and thermal aeruginosa in mechanically ventilated patients. Intensive properties of Zr-Al-Cu-Ni based amorphous alloy added with Care Med 2001;27:503−12. boron and silicon. J Metastable Nanocryst Mater 2005; 9. Braun G, Vidotto MC. Evaluation of adherence, hemaggluti- 24−25:201−4. nation, and presence of genes codifying for Acinetobacter 30. Biner SB. Ductility of bulk metallic glasses and their com- baumannii causing urinary tract infection. Mem Inst Oswaldo posites with ductile reinforcements: a numerical study. Cruz 2004;99:839−44. Acta Mater 2006;54:139−50. 10. Pfaller MA, Jones RN, Messer SA, et al. National surveillance 31. Liu CT, Lu ZP. Effect of minor alloying additions on glass forma- of nosocomial blood stream infection due to species of tion in bulk metallic glasses. Intermetallics 2005;13:415−8. Candida other than Candida albicans: frequency of occur- 32. Miracle DB. The efficient cluster packing model − An atomic rence and antifungal susceptibility in the SCOPE Program. structural model for metallic glasses. Acta Mater 2006; SCOPE Participant Group. Surveillance and Control of Path- 54:4317−36. ogens of Epidemiologic. Diagn Microbiol Infect Dis 1998; 33. Ok MR, Suh JY, Chung SJ, et al. Micro-forming and surface 30:121−9. evaluation of Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass. 11. Mandell GL, Douglas RG, Bennett JE, et al. Principles and Mater Sci Eng A Struct Mater 2007;454−455:14−8. Practice of Infectious Diseases, 6th edition. Philadelphia: 34. Ohring M. The Materials Science of Thin Films. San Diego: Churchill Livingstone, 2005. Academic Press, Inc, 1992:118−31. 12. Kuo LC, Yu CJ, Lee LN, et al. Clinical features of pandrug- 35. Donohue LA, Cawley J, Brookes JS, et al. Deposition and resistant Acinetobacter baumannii bacteremia at a univer- characterization of TiAlZrN films produced by a combined sity hospital in Taiwan. J Formos Med Assoc 2003;102:601−6. steered arc and unbalanced magnetron sputtering tech- 13. Wang SH, Sheng WH, Chang YY, et al. Healthcare-associated nique Surf Coat Technol 1995;74−75:123−34. outbreak due to pan-drug resistant Acinetobacter baumannii 36. Attar F. Hardness evaluation of thin ceramic coatings on in a surgical intensive care unit. J Hosp Infect 2003;53:97−102. tool steel. Surf Coat Technol 1996;78:78−86. 14. Acharya V, Prabha CR, Narayanamurthy C. Synthesis of 37. Gu XJ, Poon SJ, Shiflet GJ, et al. Ductility improvement of metal incorporated low molecular weight polyurethanes from amorphous steels: roles of shear modulus and electronic novel aromatic diols, their characterization and bactericidal structure. Acta Mater 2008;56:88−94. properties. Biomaterials 2004;25:4555−62. 38. Hosokawa S, Sato H, Happo N, et al. Electronic structure of 15. Koneman EW, et al. Color Atlas and Textbook of Diagnostic Pd42.5Ni7.5Cu30P20, an excellent bulk metallic glass former: Microbiololgy. Philadelphia: Lippincott Williams & Wilkins, comparison to the Pd40Ni40P20 reference glass. Acta 1997. Mater 2007;55:3413−9. 16. Aumsuwan N, Danyus RC, Heinhorst S, et al. Attachment of 39. Jakubowski W. Biofilm on biomaterials surface. In: Mitura S, ampicillin to expanded poly(tetrafluoroethylene): surface Niedzielski P, Walkowiak B, eds. NANODIAM: New Technol- reactions leading to inhibition of microbial growth. ogies for Medical Applications: Studying and Production of Biomacromolecules 2008;9:1712−8. Carbon Surfaces Allowing for Controllable Bioactivity. 17. Rodrigues L, van der Mei H, Banat IM, et al. Inhibition of Warszawa: Wydawnictwo Naukowe PWN, 2006:189−97. microbial adhesion to silicone rubber treated with biosur- 40. Quirynen M, Bollen C. The influence of surface roughness and factant from Streptococcus thermophilus A. FEMS Immunol surface free energy on supro- and subgingival plaque forma- Med Microbiol 2006;46:107−12. tion in man: a review of the literature. J Clin Periodontol 18. Noyce JO, Michels H, Keevil CW. Potential use of copper 1995;22:1−14. surfaces to reduce survival of epidemic meticillin-resistant 41. Saldarriaga Fernandez IC, van der Mei HC, Lochhead MJ, Staphylococcus aureus in the healthcare environment. et al. The inhibition of the adhesion of clinically isolated J Hosp Infect 2006;63:289−97. bacterial strains on multi-component cross-linked poly 19. Dowling DP, Betts AJ, Pope C, et al. Anti-bacterial silver (ethylene glycol)-based polymer coatings. Biomaterials coatings exhibiting enhanced activity through the addition 2007;28:4105−12. of platinum. Surf Coat Technol 2003;163−64:637−40. 42. Cringus-Fundeanu I, Luijten J, van der Mei HC, et al. 20. Zhao Q. Effect of surface free energy of graded NI-P-PTFE Synthesis and characterization of surface-grafted polyacry- coatings on bacterial adhesion. Surf Coat Technol 2004; lamide brushes and their inhibition of microbial adhesion. 185:199−204. Langmuir 2007;23:5120−6. 21. Rajapaksha RM, Tobor-Kaplon MA, Baath E. Metal toxicity 43. Cheng G, Zhang Z, Chen S, et al. Inhibition of bacterial affects fungal and bacterial activities in soil differently. adhesion and biofilm formation on zwitterionic surfaces. Appl Environ Microbiol 2004;70:2966−73. Biomaterials 2007;28:4192−9. 22. Cornelissen S, Botha A, Conradie WJ, et al. Shifts in com- 44. Hu CH, Xu ZR, Xia MS. Antibacterial effect of Cu2+-exchanged munity composition provide a mechanism for maintenance montmorillonite on Aeromonas hydrophila and discussion of activity of soil yeasts in the presence of elevated copper on its mechanism. Vet Microbiol 2005;109:83−8. levels. Can J Microbiol 2003;49:425−32. 45. Wang M, Wang WX. Cadmium toxicity in a marine diatom as 23. Kubin CJ. Antimicrobial control programs. Semin Perinatol predicted by the cellular metal sensitive fraction. Environ 2002;26:379−86. Sci Technol 2008;42:940−6. 20 P.T. Chiang et al

46. Chandra S, Jain D, Sharma AK, et al. Coordination modes of synthesis, characterization, properties and biological activity. a schiff base pentadentate derivative of 4-aminoantipyrine Spectrochim Acta A Mol Biomol Spectrosc 2008;70:634−40. with cobalt(II), nickel(II) and copper(II) metal ions: synthesis, 49. Shettlemore MG, Bundy KJ. Assessment of dental material spectroscopic and antimicrobial studies. Molecules 2009; degradation product toxicity using a bioluminescent bacterial 14:174−90. assay. Dent Mater 2002;18:445−53. 47. Gudasi KB, Patil MS, Vadavi RS. Synthesis, characterization 50. Katsikogianni M, Spiliopoulou I, Dowling DP, et al. Adhesion of of copper(II), cobalt(II), nickel(II), zinc(II) and cadmium(II) slime producing Staphylococcus epidermidis strains to PVC complexes of [7-hydroxy-4-methyl-8-coumarinyl]glycine and and diamond-like carbon/silver/fluorinated coatings. J Mater a comparative study of their microbial activities. Eur J Med Sci Mater Med 2006;17:679−89. Chem 2008;43:2436−41. 51. Lee MT, Hung WC, Chen FY, et al. Mechanism and kinetics of 48. Keskioglu E, Gündüzalp AB, Cete S, et al. Cr(III), Fe(III) and pore formation in membranes by water-soluble amphipathic Co(III) complexes of tetradentate (ONNO) Schiff base ligands: peptides. Proc Natl Acad Sci USA 2008;105:5087−92.