Facilitating GL13K Peptide Grafting on Polyetheretherketone via 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide: Surface Properties and Antibacterial Activity.

In the present work, the antimicrobial peptide (AMP) of GL13K was successfully coated onto a polyetheretherketone (PEEK) substrate to investigate its antibacterial activities against Staphylococcus aureus (S. aureus) bacteria. To improve the coating efficiency, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) was mixed with a GL13K solution and coated on the PEEK surface for comparison. Both energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) data confirmed 30% greater peptide coating on PEEK/GL13K-EDC than PEEK without EDC treatment. The GL13K graft levels are depicted in the micrograms per square centimeter range. The PEEK/GL13K-EDC sample showed a smoother and lower roughness (Rq of 0.530 µm) than the PEEK/GL13K (0.634 µm) and PEEK (0.697 µm) samples. The surface of the PEEK/GL13K-EDC was more hydrophilic (with a water contact angle of 24°) than the PEEK/GL13K (40°) and pure PEEK (89°) samples. The pure PEEK disc did not exhibit any inhibition zone against S. aureus. After peptide coating, the samples demonstrated significant zones of inhibition: 28 mm and 25 mm for the PEEK/GL13K-EDC and PEEK/GL13K samples, respectively. The bacteria-challenged PEEK sample showed numerous bacteria clusters, whereas PEEK/GL13K contained a little bacteria and PEEK/GL13K-EDC had no bacterial attachment. The results confirm that the GL13K peptide coating was able to induce antibacterial and biofilm-inhibitory effects. To the best of our knowledge, this is the first report of successful GL13K peptide grafting on a PEEK substrate via EDC coupling. The present work illustrates a facile and promising coating technique for a polymeric surface to provide bactericidal activity and biofilm resistance to medical implantable devices.

Preparation and Characterization of Thin-Film Solar Cells with Ag/C60/MAPbI3/CZTSe/Mo/FTO Multilayered Structures.

New solar cells with Ag/C60/MAPbI3/Cu2ZnSnSe4 (CZTSe)/Mo/FTO multilayered structures on glass substrates have been prepared and investigated in this study. The electron-transport layer, active photovoltaic layer, and hole-transport layer were made of C60, CH3NH3PbI3 (MAPbI3) perovskite, and CZTSe, respectively. The CZTSe hole-transport layers were deposited by magnetic sputtering, with the various thermal annealing temperatures at 300 °C, 400 °C, and 500 °C, and the film thickness was also varied at 50~300 nm The active photovoltaic MAPbI3 films were prepared using a two-step spin-coating method on the CZTSe hole-transport layers. It has been revealed that the crystalline structure and domain size of the MAPbI3 perovskite films could be substantially improved. Finally, n-type C60 was vacuum-evaporated to be the electronic transport layer. The 50 nm C60 thin film, in conjunction with 100 nm Ag electrode layer, provided adequate electron current transport in the multilayered structures. The solar cell current density-voltage characteristics were evaluated and compared with the thin-film microstructures. The photo-electronic power-conversion efficiency could be improved to 14.2% when the annealing temperature was 500 °C and the film thickness was 200 nm. The thin-film solar cell characteristics of open-circuit voltage, short-circuit current density, fill factor, series-resistance, and Pmax were found to be 1.07 V, 19.69 mA/cm2, 67.39%, 18.5 Ω and 1.42 mW, respectively.

Triggers and decision-making patterns for receiving total knee arthroplasty among older adults with knee osteoarthritis: A qualitative descriptive study.

AIMS AND OBJECTIVES: To explore triggers of and decision-making patterns for older adults with knee osteoarthritis to receive total knee arthroplasty. BACKGROUND: Older adults with knee osteoarthritis pain are often reluctant to undergo total knee arthroplasty until their physical health and psychological health have deteriorated. This delay may lead to poor long-term outcomes after the surgery. Thus, it is important to help these older adults decide to undergo total knee arthroplasty in an appropriate time frame. DESIGN: A qualitative descriptive study. METHODS: Older adult outpatients scheduled to receive total knee arthroplasty within 1 month (N = 79) were recruited by convenience from two medical centres and one regional hospital in northern Taiwan. Data were collected in individual interviews using a semistructured guide and analysed by thematic analysis. RESULTS: The main triggers for older adults to receive total knee arthroplasty were severe pain and inability to walk. We identified four decision-making patterns for undergoing total knee arthroplasty: tried everything to relieve pain and surgery was the last choice; previously received total knee arthroplasty; perceived oneself as still young and wanted to enjoy life; and adjusted work characteristics, but in vain. CONCLUSION: Healthcare providers of older patients with knee osteoarthritis must carefully assess their characteristics, especially age, occupation and previous total knee arthroplasty, to guide them in deciding to undergo total knee arthroplasty. Clinicians also need to provide appropriate information about osteoarthritis care, pain medications, total knee arthroplasty, the relationship between knee osteoarthritis pain and quality of life, as well as the relationship between preoperative status and postoperative long-term outcomes for older adults to maintain their quality of life. RELEVANCE TO CLINICAL PRACTICE: Our findings provide evidence for healthcare providers to offer information and support to their older adult patients with knee-osteoarthritis pain who are deciding whether to undergo total knee arthroplasty.

Topical tranexamic acid reduces blood loss and transfusion rates associated with primary total hip arthroplasty.

BACKGROUND: Systemic tranexamic acid can decrease blood loss and rates of transfusion in patients undergoing total hip arthroplasty (THA). However, the efficacy of topical tranexamic acid in THA has only recently been characterized in a small number of studies. QUESTIONS/PURPOSES: The purpose of this study was to compare (1) the greatest hemoglobin decrease after surgery; (2) transfusion rates; and (3) symptomatic thromboembolic events among patients undergoing THA who did and did not receive topical tranexamic acid. METHODS: We retrospectively compared 135 patients (154 THAs) who received 10 mL 5% tranexamic acid added in a topical cocktail solution during surgery between January 2009 and July 2011 with 211 patients (234 THAs) who received only the topical cocktail solution (analgesic and antibiotic agent) between January 2005 and December 2008. Contraindications for the use of tranexamic acid included a documented history of a venous thromboembolic event, an allergy to tranexamic acid, thrombophilia, or a high risk of venous thromboembolism based on the guidelines of the American Academy of Orthopaedic Surgeons; the 135 patients who received it during that period represented 99.4% of the patients undergoing THA during that time. We compared changes in Hb, transfusion rates, estimated blood loss, surgical results, and complications between the groups. The transfusion threshold was the same, when the Hb values were < 10 g/dL. Patients were screened for thromboembolic disease if symptoms or signs appeared. RESULTS: Hb decreased less in the tranexamic acid group (1.87 ± 1.10 g/dL) than in the control group (2.2 ± 1.36 g/dL; p = 0.01) on the first postoperative day. The frequency of transfusion was lower in patients receiving tranexamic acid (17% as compared with 35% in the control group; p < 0.001). There was only one nonfatal pulmonary embolism in the control group during the study period. CONCLUSIONS: Use of topical tranexamic acid in patients undergoing THA reduces postoperative bleeding and decreases blood transfusion rates. No increase in major complications was identified in patients managed with topical tranexamic acid. This retrospective study confirms the results of a smaller randomized trial on the same topic by another group. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Intra-articular bupivacaine reduces postoperative pain and meperidine use after total hip arthroplasty: a randomized, double-blind study.

One hundred patients receiving unilateral total hip arthroplasty (THA) were randomized to receive an intra-articular injection of 300mg bupivacaine or normal saline after completion of surgery. Pain scores of the bupivacaine group were significantly lower than those of the control group the first 12hours postoperatively (all, P<0.001). A significantly lower dose of meperidine was used in the study group than in the control group the first 24hours postoperatively (median, 25 vs. 45mg, P<0.001). Nineteen patients in the study group required meperidine the first day after surgery, as compared to 45 patients in the control group. We conclude that intra-articular injection of bupivacaine after THA reduces pain and meperidine use in the first 12hours after surgery.

The influence of storage temperature on the antibiotic release of vancomycin-loaded polymethylmethacrylate.

Periprosthetic joint infection is devastating and increases medical expenditure and socioeconomic burden. Antibiotic-loaded cement spacer is useful in the interim period before the reimplantation surgery. Prefabricated antibiotic-loaded cement spacers can decrease operation time but have been limitedly used clinically. In the literature, there is no clear recommendation on the storage temperature for the prefabricated cement spacers. We used an in vitro model to analyze whether the storage temperature at 25°C, 4°C, or -20°C for 2 weeks or 3 months could affect the release of vancomycin from the cement. We found that the storage temperature and time had no significant effects on the pattern and amount of vancomycin release. The patterns of vancomycin release from the cement stored at different temperatures were similar with an abrupt release in the first 3 days and steadily declined in the following period. This study provides a preliminary result to justify the storage of fabricating antibiotic-loaded cement spacer sterilely packed at room temperature. Further studies to examine the effects of storage temperature on the mechanical strength and the release pattern of other antibiotics should be done to provide more evidence to support the clinical use of prefabricated ready-to-use antibiotic-loaded cement spacer.

Antimicrobial Peptide Conjugated on Graphene Oxide-Containing Sulfonated Polyetheretherketone Substrate for Effective Antibacterial Activities against Staphylococcus aureus.

In the present study, the antimicrobial peptide nisin was successfully conjugated onto the surface of sulfonated polyetheretherketone (SPEEK), which was decorated with graphene oxide (GO) to investigate its biofilm resistance and antibacterial properties. The PEEK was activated with sulfuric acid, resulting in a porous structure. The GO deposition fully covered the porous SPEEK specimen. The nisin conjugation was accomplished using the crosslinker 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) through a dip-coating method. The surface micrographs of the SPEEK-GO-nisin sample indicated that nisin formed discrete islets on the flat GO surface, allowing both the GO and nisin to perform a bactericidal effect. The developed materials were tested for bactericidal efficacy against Staphylococcus aureus (S. aureus). The SPEEK-GO-nisin sample had the highest antibacterial activity with an inhibition zone diameter of 27 mm, which was larger than those of the SPEEK-nisin (19 mm) and SPEEK-GO (10 mm) samples. Conversely, no inhibitory zone was observed for the PEEK and SPEEK samples. The surface micrographs of the bacteria-loaded SPEEK-GO-nisin sample demonstrated no bacterial adhesion and no biofilm formation. The SPEEK-nisin and SPEEK-GO samples showed some bacterial attachment, whereas the pure PEEK and SPEEK samples had abundant bacterial colonies and thick biofilm formation. These results confirmed the good biofilm resistance and antibacterial efficacy of the SPEEK-GO-nisin sample, which is promising for implantable orthopedic applications.

Pain distribution and response to total hip arthroplasty: a prospective observational study in 113 patients with end-stage hip disease.

PURPOSE: The aim of this study was to investigate the pain patterns in patients with end-stage hip disease and to assess the response after total hip arthroplasty (THA). METHODS: The pain patterns of patients undergoing THA for end-stage hip diseases were prospectively evaluated by requesting them to mark a map of body areas before and after surgery. Patients were excluded if they had coexisting pathology of the knee or spine. The pain measurements were quantified using visual analog scales, and factors that may contribute to different pain patterns were also evaluated. RESULTS: Among 113 patients (113 hips) enrolled in the study, the groin, anterior thigh, buttock, anterior knee, and greater trochanter were the most common pain locations before THA. Pain over the lower back, shin, and calf areas, which were not generally considered referral pain areas from hip diseases, was present in 21.2, 7.1, and 2.7% patients, respectively. The presence of lower back pain (LBP) was statistically more common in patients with longer duration of hip symptoms. Regardless of the different pain patterns, 97.3% (110 of 113) of patients reported complete pain relief within 12 weeks after THA. CONCLUSIONS: The distribution of pain from end-stage hip diseases is versatile, and presence of pain in areas other than around the hip is not uncommon. LBP was more common in patients with longer duration of symptoms. THA satisfactorily resolves the pain in all areas soon after surgery.

Antibacterial Activity Studies of 3D-Printing Polyetheretherketone Substrates with Surface Growth of 2D TiO2/ZnO Rodlike Arrays.

Heterogeneous metal implants have been applied in clinical treatments of skeletal wounds, but their low antibacterial properties and the possibility of a release of metal ions may have harmful influences on the human body. Therefore, a polymer implant with low cost, high safety, an elastic modulus similar to that of human bone, and a good antibacterial property must be produced for orthopedic treatments. In this study, the surface of a 3D-printed polyetheretherketone (PEEK) disk was grown with ZnO/TiO2 rodlike arrays using a chemical bath deposition. X-ray diffraction patterns and transmission electron microscopy images showed that TiO2/ZnO rodlike arrays were deposited onto the PEEK substrate. With the direct absorption of antibiotic agents onto the surface of TiO2/ZnO/PEEK samples, their antibacterial performances greater than the values of minimum inhibitory concentration required to inhibit the growth of 90% of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) remained for around 10 days. The concentration of Zn2+ ions in a buffer solution is reduced with the coating of a TiO2 layer on a ZnO rodlike array. The sample with absorption from a mixture containing ampicillin and vancomycin salts with a weight ratio of 1:1 had the best inhibitory effect on the growth of E. coli and S. aureus.

Prismatic Silver Nanoparticles Decorated on Graphene Oxide Sheets for Superior Antibacterial Activity.

Spherical silver nanoparticles (Ag NPs) and silver nanoprisms (Ag NPrsms) were synthesized and decorated on graphene oxide (GO) nanosheets. The Ag contents were 29% and 23% in the GO−Ag NPs and GO−Ag NPrsms, respectively. The Ag NPrsms exhibited stronger (111) crystal signal than Ag NPs. The GO−Ag NPrsms exhibited higher Ag (I) content (75.6%) than GO-Ag NPs (69.9%). Increasing the nanomaterial concentration from 25 to 100 µg mL−1 improved the bactericidal efficiency, and the antibacterial potency was in the order: GO−Ag NPrsms > GO−Ag NPs > Ag NPrsms > Ag NPs > GO. Gram-positive Staphylococcus aureus (S. aureus) was more vulnerable than Gram-negative Escherichia coli (E. coli) upon exposure to these nanomaterials. The GO−Ag NPrsms demonstrated a complete (100%) bactericidal effect against S. aureus at a concentration of 100 µg mL−1. The GO−Ag composites outperformed those of Ag or GO due to the synergistic effect of bacteriostatic Ag particles and GO affinity toward bacteria. The levels of reactive oxygen species produced in the bacteria−nanomaterial mixtures were highly correlated to the antibacterial efficacy values. The GO−Ag NPrsms are promising as bactericidal agents to suppress biofilm formation and inhibit bacterial infection.

In vitro activities of daptomycin-, vancomycin-, and teicoplanin-loaded polymethylmethacrylate against methicillin-susceptible, methicillin-resistant, and vancomycin-intermediate strains of Staphylococcus aureus.

The objective of this study was to evaluate the antibacterial effects of polymethylmethacrylate (PMMA) bone cements loaded with daptomycin, vancomycin, and teicoplanin against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-intermediate Staphylococcus aureus (VISA) strains. Standardized cement specimens made from 40 g PMMA loaded with 1 g (low-dose), 4 g (middle-dose) or 8 g (high-dose) antibiotics were tested for elution characteristics and antibacterial activities. The patterns of release of antibiotics from the cement specimens were evaluated using in vitro broth elution assay with high-performance liquid chromatography. The activities of broth elution fluid against different Staphylococcus aureus strains (MSSA, MRSA, and VISA) were then determined. The antibacterial activities of all the tested antibiotics were maintained after being mixed with PMMA. The cements loaded with higher dosages of antibiotics showed longer elution periods. Regardless of the antibiotic loading dose, the teicoplanin-loaded cements showed better elution efficacy and provided longer inhibitory periods against MSSA, MRSA, and VISA than cements loaded with the same dose of vancomycin or daptomycin. Regarding the choice of antibiotics for cement loading in the treatment of Staphylococcus aureus infection, teicoplanin was superior in terms of antibacterial effects.

In vitro and in vivo investigation of drug-eluting implants for the treatment of periodontal disease.

This paper developed solvent-free drug-eluting implants for metronidazole delivery for the treatment of periodontal disease and investigated the characteristics of the drug's release from the implants, both in vitro and in vivo, using an HPLC assay. The metronidazole exhibited a two-stage release behavior in vitro with an initial burst release followed by a diffusion-controlled release and then a secondary burst release. The accumulated drug release reached 100% on the 18th day, and the drug-eluting implant was totally dissolved on the same day. Additionally, the drug-eluting disks were implanted within the sub-gingival space of both lower incisors of six rabbits. The curve of in vivo drug release was smoother and showed a predominantly diffusion-controlled release. The implants were totally dissolved at 2 weeks after implantation. The concentration of metronidazole remained above the MIC(90) during the entire investigation.

The impact of systemic lupus erythematosus on the risk of infection after total hip arthroplasty: a nationwide population-based matched cohort study.

BACKGROUND: We aimed to assess the impact of systemic lupus erythematosus (SLE) on the risk of infection after total hip arthroplasty (THA). METHODS: We identified patients undergoing primary THA (1996-2013) in Taiwan National Health Insurance Research Database (NHIRD). Patients were then divided into the SLE and control groups according to the diagnosis of SLE. We used 1:1 propensity score to match the control to the SLE group by age, sex, and comorbidities. The primary outcome was infection, including early and late superficial wound infection and periprosthetic joint infection (PJI). The secondary outcome was in-hospital complications. RESULTS: We enrolled 325 patients in each group. In the primary outcome, the incidence of early superficial wound infection and PJI was comparable between the SLE and matched-control group. However, the incidence of late superficial wound infection and PJI in the SLE group was higher than that in matched-control group (11.4% vs. 5.5%, P = 0.01; 5.2% vs 2.2%, P = 0.04, respectively). Furthermore, the SLE group had a higher risk for late superficial wound infection and PJI (hazard ratio = 2.37, 95% confidence interval (CI) 1.35-4.16; HR = 2.74, 95% CI 1.14-6.64, respectively) than the matched-control. Complications other than infection and in-hospital mortality cannot be compared because of very low incidence. CONCLUSIONS: SLE is a risk factor for developing late superficial wound infection and PJI, but not for early postoperative complications following THA. Clinical presentations should be monitored to avoid misdiagnosis of PJI in SLE patients after THA.

Increased incidence, morbidity, and mortality in cirrhotic patients with hip fractures: A nationwide population-based study.

OBJECTIVES: Hip fractures mostly require surgical treatment and are associated with increased health-care costs and mortality rates. Patients with cirrhosis have low bone marrow density and inferior immune status which contribute to a higher fracture rate and higher surgical complication rate. This population-based study evaluated the prevalence, complication, and mortality rates due to hip fractures in cirrhotic patients. METHODS: Taiwan National Health Insurance Research Database data were used. The study group included 117,129 patients with hip fractures diagnosed from 2004 to 2010, including 4048 patients with cirrhosis. The overall prevalence, morbidity, and mortality rates of the cirrhosis group with hip fractures were compared with the rates of a general group with hip fractures. RESULTS: The cirrhosis group patients were younger than the general group patients (71.2 vs. 73.96 years, p < 0.001). The annual incidence of hip fractures in the cirrhosis and general groups was 46-54 and 7-7.5 per 10,000 person-years, respectively, with an incidence rate ratio of 6.95 (95% confidence interval 6.74-7.18). The rates of infection, urinary tract infection, and peptic ulcer disease were higher in the cirrhosis group (3.46% vs. 1.91%, 9.56% vs. 9.11%, and 8.05% vs. 3.55%, respectively; all p < 0.001). The mortality rate after hip fracture was also higher in the cirrhosis group than in the general group (within 3 months: 8.76-12.64% vs. 4.96-5.30% and within 1 year: 29.72-37.99% vs. 12.84-14.57%). Conclusion: Cirrhotic patients with hip fractures were relatively younger; had a seven times higher annual hip fracture incidence; had higher complication rates of infection, urinary tract infection, and peptic ulcer disease; and had two to three times higher a mortality rate at 3 months and 1 year. Clinicians should pay particular attention to the possibility of osteoporosis and hip fractures in patients with liver cirrhosis. LEVEL OF EVIDENCE: Level III, case-control study.

Size-Dependent Antibacterial Activity of Silver Nanoparticle-Loaded Graphene Oxide Nanosheets.

A series of graphene oxide (GO) suspensions with different particle sizes (<100 nm, ~100 nm, ~1 µm and >1 µm) were successfully fabricated after 0, 30, 60 and 120 min of sonication, respectively. The antibacterial properties of GO suspensions showed that >1 µm GO size resulted in a loss of nearly 50% of bacterial viability, which was higher than treatment by ~100 nm GO size (25%) towards Escherichia coli (E. coli). Complete entrapment of bacteria by the larger GO was observed in transmission electron microscopy (TEM). Silver nanoparticles (Ag NPs) were doped onto GO samples with different lateral sizes to form GO-Ag NP composites. Resulting larger GO-Ag NPs showed higher antibacterial activity than smaller GO-Ag NPs. As observed by Fourier transform infrared spectroscopy (FTIR), the interaction between E. coli and GO occurred mainly at the outer membrane, where membrane amino acids interact with hydroxyl and epoxy groups. The reactive oxygen species (ROS) and the considerable penetration of released Ag+ into the inner bacterial cell membrane result in loss of membrane integrity and damaged morphology. The present work improves the combined action of GO size effect with constant Ag loadings for potential antibacterial activity.

Synergistic Antibacterial Activity of Silver-Loaded Graphene Oxide towards Staphylococcus Aureus and Escherichia Coli.

In this study, the physicochemical and surface properties of the GO-Ag composite promote a synergistic antibacterial effect towards both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. Aureus) bacteria. GO-Ag NPs have a better bactericidal effect on E. coli (73%) and S. Aureus (98.5%) than pristine samples (pure Ag or GO). Transmission electron microscopy (TEM) confirms that the GO layers folded entire bacteria by attaching to the membrane through functional groups, while the Ag NPs penetrated the inner cell, thus damaging the cell membrane and leading to cell death. Cyclic voltammetry (CV) tests showed significant redox activity in GO-Ag NPs, enabling good catalytic performance towards H2O2 reduction. Strong reactive oxygen species (ROS) in GO-Ag NPs suggests that ROS might be associated with bactericidal activity. Therefore, the synergy between the physicochemical effect and ROS production of this material is proposed as the mechanism of its antibacterial activity.

Effects of Annealing on Characteristics of Cu2ZnSnSe4/CH3NH3PbI3/ZnS/IZO Nanostructures for Enhanced Photovoltaic Solar Cells.

This paper presents new photovoltaic solar cells with Cu2ZnSnSe4/CH3NH3PbI3(MAPbI3)/ZnS/IZO/Ag nanostructures on bi-layer Mo/FTO (fluorine-doped tin oxide) glasssubstrates. The hole-transporting layer, active absorber layer, electron-transporting layer, transparent-conductive oxide layer, and top electrode-metal contact layer, were made of Cu2ZnSnSe4, MAPbI3 perovskite, zincsulfide, indium-doped zinc oxide, and silver, respectively. The active absorber MAPbI3 perovskite film was deposited on Cu2ZnSnSe4 hole-transporting layer that has been annealed at different temperatures. TheseCu2ZnSnSe4 filmsexhibitedthe morphology with increased crystal grain sizesand reduced pinholes, following the increased annealing temperature. When the perovskitefilm thickness was designed at 700 nm, the Cu2ZnSnSe4 hole-transporting layer was 160 nm, and the IZO (indium-zinc oxide) at 100 nm, and annealed at 650 °C, the experimental results showed significant improvements in the solar cell characteristics. The open-circuit voltage was increased to 1.1 V, the short-circuit current was improved to 20.8 mA/cm2, and the device fill factor was elevated to 76.3%. In addition, the device power-conversion efficiency has been improved to 17.4%. The output power Pmax was as good as 1.74 mW and the device series-resistance was 17.1 Ω.

Study of High Performance Sulfonated Polyether Ether Ketone Composite Electrolyte Membranes.

In this study, high performance composite electrolyte membranes were prepared from polyether ether ketone polymeric material. An initial sulfonation reaction improved the membrane hydrophilicity and its water absorbability and thus enhanced the ionic conductivity in electrochemical cells. Protonic conductivity was improved from 10-4 to 10-2 S cm-1 with an increasing sulfonation time from 72 to 175 h. The effects of blending nano SiO2 into the composite membranes were devoted to improve thermal and mechanical properties, as well as methanol permeability. Methanol permeability was reduced to 3.1 × 10-7 cm2 s-1. Finally, a further improvement in ionic conductivity was carried out by a supercritical carbon dioxide treatment under 20 MPa at 40°C for 30 min with an optimum SiO2 blend ratio of 10 wt-%. The plasticizing effect by the Lewis acid-base interaction between CO2 and electron donor species on polymer chains decreased the glass transition and melting temperatures. The results show that sulfonated composite membranes blended with SiO2 and using a supercritical carbon dioxide treatment exhibit a lower glass transition temperature, higher ionic conductivity, lower methanol permeability, good thermal stability, and strong mechanical properties. Ionic conductivity was improved to 1.55 × 10-2 S cm-1. The ion exchange capacity and the degree of sulfonation were also investigated.

Antibacterial Application on Staphylococcus aureus Using Antibiotic Agent/Zinc Oxide Nanorod Arrays/Polyethylethylketone Composite Samples.

In this study, zinc oxide (ZnO) nanorod arrays as antibiotic agent carriers were grown on polyetheretherketone (PEEK) substrates using a chemical synthesis method. With the concentration of ammonium hydroxide in the precursor solution kept at 4 M, ZnO nanorod arrays with diameters in the range of 100-400 nm and a loading density of 1.7 mg/cm2 were grown onto the PEEK substrates. Their drug release profiles and the antibacterial properties of the antibiotic agent/ZnO/PEEK samples in the buffer solution were investigated. The results showed that the concentrations of antibiotic agents (ampicillin or vancomycin) released from the samples into the buffer solution were higher than the value of minimum inhibitory concentration of 90% for Staphylococcus aureus within the 96 h test. The bioactivities of ampicillin and vancomycin on substrates also showed around 40% and 80% on the Staphylococcus aureus, respectively. In the antibacterial activity test, sample with the suitable loading amount of antibiotic agent had a good inhibitory effect on the growth of Staphylococcus aureus.

Osteoblast Biocompatibility and Antibacterial Effects Using 2-Methacryloyloxyethyl Phosphocholine-Grafted Stainless-Steel Composite for Implant Applications.

Poor osteogenesis and bacterial infections lead to an implant failure, so the enhanced osteogenic and antimicrobial activity of the implantable device is of great importance in orthopedic applications. In this study, 2-methacryloyloxyethyl phosphocholine (MPC) was grafted onto 316L stainless steel (SS) using a facile photo-induced radical graft polymerization method via a benzophenone (BP) photo initiator. Atomic force microscopy (AFM) was employed to determine the nanoscale morphological changes on the surface. The grafted BP-MPC layer was estimated to be tens of nanometers thick. The SS-BP-MPC composite was more hydrophilic and smoother than the untreated and BP-treated SS samples. Staphylococcus aureus (S. aureus) bacteria binding onto the SS-BP-MPC composite film surface was significantly reduced compared with the pristine SS and SS-BP samples. Mouse pre-osteoblast (MC3T3-E1) cells showed good adhesion on the MPC-modified samples and better proliferation and metabolic activity (73% higher) than the pristine SS sample. Biological studies revealed that grafting MPC onto the SS substrate enhanced the antibacterial efficiency and also retained osteoblast biocompatibility. This proposed procedure is promising for use with other implant materials.