Antibacterial silver-containing silica glass prepared by sol-gel method

Development of new sol-gel derived Ag-doped biomaterials for dental applications

The aim of this work was to develop a new Ag-doped bioactive material with antibacterial behavior, optimizing the properties of the new fabricated composite material in the system SiO2 58.6 -P2O5 7.2 -Al2O3 4.2 -CaO 24.9 -Na2O 2.1 -K2O 3 (wt%). Two systems with different concentrations in Ag2O (Ba with 2.1 and Bb with 4.2 wt%) were prepared by the sol-gel method and compared to the respective silver-free control composite (CONTROL). The microstructural characteristics of the developed compositions were characterized by different techniques as UV/VIS spectroscopy, X-ray diffraction analysis (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). The antibacterial properties of the Ag-doped glass-ceramics were tested against the bacterial colony Staphylococcus aureus (S. aureus) which is very characteristic oral bacteria and the material-cell interaction was monitored in a primary culture of Human Gingival Fibroblasts (HGFs). Our study shows the successful incorporation of the silver ions in the ceramic structure and the preparation of new Ag-doped composite materials with cell-proliferation-inductive, as well as antibacterial properties indicating their potential application dental tissue restoration strategies.

Validity of silver, chitosan, and curcumin nanoparticles as anti-Giardia agents

This study was carried out to evaluate the anti parasitic potential of silver, chitosan, and curcumin nanoparticles as anti-Giardia agents. Non-treated infected control rats were inoculated with Giardia lamblia cysts in a dose of 2 × 10(5) cysts/rat. Experimental group was infected then treated with curcumin, curcumin nanoparticles, chitosan, chitosan nanoparticles, and silver nanoparticles as single or combined therapy. The number of Giardia cysts in stools and trophozoites in intestinal sections were detected. Toxicity of nanoparticles was evaluated by comparing hematological and histopathological parameters of the normal control group and treated non-infected control group. The amount of silver was also measured in the liver, kidney, small intestine, lung, and brain of rats treated with silver nanoparticles. The number of the parasites in stool and small intestinal sections decreased in treated infected rats compared with infected non-treated ones. The effect in the single therapy was better with nanoparticles, and the best effect was detected in nano-silver. The combined therapy gave better results than single. Combination between nanoparticles was better than the combination of nano-forms and native chitosan and curcumin. The best effect was detected in combinations of nano-silver and nano-chitosan but with no full eradication. In conclusion, the highest effect and complete cure was gained by combining the three nano-forms. The parasite was successfully eradicated from stool and intestine. None of the treatments exhibited any toxicity. Accumulated silver in different organs was within the safe limits.

Metallic ions as therapeutic agents in tissue engineering scaffolds: an overview of their biological applications and strategies for new developments

This article provides an overview on the application of metallic ions in the fields of regenerative medicine and tissue engineering, focusing on their therapeutic applications and the need to design strategies for controlling the release of loaded ions from biomaterial scaffolds. A detailed summary of relevant metallic ions with potential use in tissue engineering approaches is presented. Remaining challenges in the field and directions for future research efforts with focus on the key variables needed to be taken into account when considering the controlled release of metallic ions in tissue engineering therapeutics are also highlighted.

Ag-Doped Sol-Gel Derived Novel Composite Materials for Dental Applications

The aim of this work was to improve a newly developed family of glass-ceramic composite materials by incorporating silver ions in the ceramic structure, thus developing new Ag-doped materials with the ability of showing antibacterial activity for dental applications. Two different sol-gel methodologies were applied for the fabrication of colorless, homogenous and chemically durable materials which can slowly release silver ion for relatively long periods. Both methods led to the successful development of Ag-doped glass-ceramics with silver ions incorporated in the structure that can slowly release in buffer solution, during a period of 45 days. The potential, application of these materials involve the development of bioactive surfaces on dental substrates which can seal the marginal gap creating a bacterial free environment finally supporting the success of dental restorations.

Natural tubule clay template synthesis of silver nanorods for antibacterial composite coating

Halloysite is naturally available clay mineral with hollow cylindrical geometry and it is available in thousands of tons. Silver nanorods were synthesized inside the lumen of the halloysite by thermal decomposition of the silver acetate, which was loaded into halloysite from an aqueous solution by vacuum cycling. Images of individual ca. 15 nm diameter silver nanorods and nanoparticles were observed with TEM. The presence of silver inside the tubes was also verified with STEM-EDX elemental mapping. Nanorods had crystalline nature with [111] axis oriented ~68° from the halloysite tubule main axis. The composite of silver nanorods encased in clay tubes with the polymer paint was prepared, and the coating antimicrobial activity combined with tensile strength increase was demonstrated. Coating containing up 5% silver loaded halloysite did not change color after light exposure contrary to the sample prepared with loading with unshelled silver nanoparticles. Halloysite tube templates have a potential for scalable manufacturing of ceramic encapsulated metal nanorods for composite materials.

Large-scale preparation of strawberry-like, AgNP-doped SiO2 microspheres using the electrospraying method

In this paper, we report on a novel strategy for the preparation of silver nanoparticle-doped SiO(2) microspheres (Ag-SMSs) with an interesting strawberry-like morphology using a simple and efficient electrospraying method. SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (x-ray diffraction), EDS (energy-dispersive spectroscopy) and UV-vis spectra (ultraviolet-visible spectra) were applied to investigate the morphology, structure, composition and optical properties of the hybrid microspheres, and E. coli (Escherichia coli) was used as a model microbe to evaluate their antibacterial ability. The results showed that the Ag-SMSs were environmentally stable and washing resistant. The Ag-SMSs exhibited effective inhibition against proliferation of E. coli, and their antibacterial ability could be well preserved for a long time. The environmental stability, washing resistance, efficient antibacterial ability and simple but productive preparation method endowed the Ag-SMSs with great potential for practical biomedical applications.

Antifungal activity of denture soft lining material modified by silver nanoparticles-a pilot study

Soft liner materials in oral cavity environments are easily colonized both by fungi and dental plaque. These factors are the cause of mucosal infections. The microorganism that most frequently colonizes soft liner materials is Candida albicans. Colonization occurs on the surface of materials and within materials. A solution to this problem might involve modification of soft liner materials with silver nanoparticles (AgNPs). In this article, we present results showing the antifungal efficacy of silicone soft lining materials modified with AgNPs. The modification process was conducted by dissolving both material components (base and catalyst) in a colloidal solution of AgNPs and evaporating the solvent. Composites with various AgNP concentrations (10, 20, 40, 80, 120 and 200 ppm) were examined. The in vitro antifungal efficacy (AFE) of composite samples was 16.3% to 52.5%.

Characterization and antibacterial efficacy of silver-coated Ca–Na–Zn–Si/Ti glasses

A glass series [ xSiO2[ −y]·0.36ZnO·0.17Na2O·0.05CaO (starting at x = 0.50, y = 0.08 TiO2)] was formulated with TiO2 substituting SiO2. Each glass/silver-coated glass was characterized using X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. Surface area analysis revealed significant changes after silver coating, 0.43–0.95 m2/g (control), to 0.53–1.85 m2/g (AU-1), and 0.20–1.11 m2/g (AU-2). Ion release from uncoated glasses included sodium (0.08 mg/L), calcium (0.07 mg/L), and zinc (0.008 mg/L), where silver-coated glasses presented 0.42 mg/L (silver), 0.33 mg/L (sodium), 0.02 mg/L (calcium), and 0.01 mg/L (zinc). Ag-coated glasses presented inhibition zones of 7.75 mm (control) compared to 1.04 mm (AU-2).

An antibacterial coating based on a polymer/sol-gel hybrid matrix loaded with silver nanoparticles

In this work a novel antibacterial surface composed of an organic-inorganic hybrid matrix of tetraorthosilicate and a polyelectrolyte is presented. A precursor solution of tetraethoxysilane (TEOS) and poly(acrylic acid sodium salt) (PAA) was prepared and subsequently thin films were fabricated by the dip-coating technique using glass slides as substrates. This hybrid matrix coating is further loaded with silver nanoparticles using an in situ synthesis route. The morphology and composition of the coatings have been studied using UV-VIS spectroscopy and atomic force microscopy (AFM). Energy dispersive X-ray (EDX) was also used to confirm the presence of the resulting silver nanoparticles within the thin films. Finally the coatings have been tested in bacterial cultures of genus Lactobacillus plantarum to observe their antibacterial properties. It has been experimentally demonstrated that these silver loaded organic-inorganic hybrid films have a very good antimicrobial behavior against this type of bacteria.

Facile synthesis of Ag nanoparticles supported on MWCNTs with favorable stability and their bactericidal properties

Stable Ag nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) have been successfully synthesized by calcinations of the complexes of Ag cation and acid-treated MWCNTs under sparging N(2). The nanocomposites are characterized in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-visible absorption spectroscopy. The results indicate that Ag nanoparticles are relatively homogeneously dispersed on the surface of MWCNTs. The bactericidal properties of Ag/MWCNT nanocomposites are investigated with disk diffusion assay on the suspension samples inoculated with Escherichia coli. The results show that Ag/MWCNTs-500 nanocomposites possess excellent bactericidal property because of their suitable particle size (15 nm). Moreover, Ag nanoparticles supported on MWCNTs are very stable for half a year. What is more, the bactericidal effect was enhanced obviously under solar irradiation. This is because MWCNTs can absorb near-infrared light to kill parts of bacteria. A possible formation mechanism is also proposed in this article.

A review of the biological response to ionic dissolution products from bioactive glasses and glass-ceramics

Several inorganic materials such as special compositions of silicate glasses, glass-ceramics and calcium phosphates have been shown to be bioactive and resorbable and to exhibit appropriate mechanical properties which make them suitable for bone tissue engineering applications. However, the exact mechanism of interaction between the ionic dissolution products of such inorganic materials and human cells are not fully understood, which has prompted considerable research work in the biomaterials community during the last decade. This review comprehensively covers literature reports which have investigated specifically the effect of dissolution products of silicate bioactive glasses and glass-ceramics in relation to osteogenesis and angiogenesis. Particularly, recent advances made in fabricating dense biomaterials and scaffolds doped with trace elements (e.g. Zn, Sr, Mg, and Cu) and investigations on the effect of these elements on the scaffold biological performance are summarized and discussed in detail. Clearly, the biological response to artificial materials depends on many parameters such as chemical composition, topography, porosity and grain size. This review, however, focuses only on the ion release kinetics of the materials and the specific effect of the released ionic dissolution products on human cell behaviour, providing also a scope for future investigations and identifying specific research needs to advance the field. The biological performance of pure and doped silicate glasses, phosphate based glasses with novel specific compositions as well as several other silicate based compounds are discussed in detail. Cells investigated in the reviewed articles include human osteoblastic and osteoclastic cells as well as endothelial cells and stem cells.

In situ formation of silver nanoparticles in photocrosslinking polymers

Nanocomposites of cross-linked methacrylate polymers with silver nanoparticles have been synthesized by coupling photoinitiated free radical polymerization of dimethacrylates with in situ silver ion reduction. A polymerizable methacrylate bearing a secondary amino functional group was used to increase the solubility of the silver salt in the hydrophobic resin system. Fourier transform infrared spectroscopy (FTIR) revealed that the silver ion reduction had no significant effect on the degree of vinyl conversion of the methacrylate. X-ray photoelectron spectroscopy (XPS) measurements showed an increased silver concentration at the composite surface compared to the expected concentration based on the total amount of silver salt added. Furthermore, the surface silver concentration leveled off when the silver salt mass fractions were 0.08% or greater. Composites with low concentrations of silver salt (< 0.08% by mass) exhibited comparable mechanical properties to those containing no silver. Transmission electron microscopy (TEM) confirmed that the silver nanoparticles formed within the polymer matrix were nanocrystalline in nature and primarily ≈ 3 nm in diameter, with some large particle aggregates. Composites containing silver nanoparticles were shown to reduce bacterial colonization with as little as 0.03% (by mass) silver salt, while additional amounts of silver salt did not further decrease their surface colonization. With a substantial effect on bacterial growth and minimal effects on mechanical properties, the in situ formation of silver nanoparticles within methacrylate materials is a promising technique for synthesizing antibacterial nanocomposites for biomedical applications.

Synthesis and characterization of silver/montmorillonite/chitosan bionanocomposites by chemical reduction method and their antibacterial activity

Silver nanoparticles (AgNPs) of a small size were successfully synthesized using the wet chemical reduction method into the lamellar space layer of montmorillonite/chitosan (MMT/Cts) as an organomodified mineral solid support in the absence of any heat treatment. AgNO3, MMT, Cts, and NaBH4 were used as the silver precursor, the solid support, the natural polymeric stabilizer, and the chemical reduction agent, respectively. MMT was suspended in aqueous AgNO3/Cts solution. The interlamellar space limits were changed (d-spacing = 1.24–1.54 nm); therefore, AgNPs formed on the interlayer and external surface of MMT/Cts with d-average = 6.28–9.84 nm diameter. Characterizations were done using different methods, ie, ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, and Fourier transform infrared spectroscopy. Silver/montmorillonite/chitosan bionanocomposite (Ag/MMT/Cts BNC) systems were examined. The antibacterial activity of AgNPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria, ie, Escherichia coli, E. coli O157:H7, and Pseudomonas aeruginosa by the disc diffusion method using Mueller Hinton agar at different sizes of AgNPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biological research and biomedical applications, including surgical devices and drug delivery vehicles.

Towards long-lasting antibacterial stainless steel surfaces by combining double glow plasma silvering with active screen plasma nitriding

Antibacterial surface modification of biomedical materials has evolved as a potentially effective method for preventing bacterial proliferation on the surfaces of devices. However, thin antibacterial coatings or modified layers can be easily worn down when interacting with other surfaces in relative motion, thus leading to a low durability of the antibacterial surface. To this end, novel biomaterial surfaces with antibacterial Ag agents and a wear-resistant S-phase have been generated on stainless steel by duplex plasma silvering-nitriding techniques for application to load-bearing medical devices. The chemical composition, microstructure, surface topography, roughness and wettability of SS surfaces were characterised using glow discharge optical emission spectroscopy, energy-dispersive spectroscopy/wavelength dispersive spectrometry (WDS), X-ray diffraction, atomic force microscopy and a contact angle goniometer. Optimal surface design for high antimicrobial activity and prolonged durability has been achieved, as evidenced by rapid bacterial killing rates (within 6h), an ultra hard matrix (875 ± 25 Hv), high load-bearing capacity (critical load 37 N) and excellent wear resistance (wear rate 4.9 × 10⁻⁶ mm³ m⁻¹). Ag embedded in the hard substrate of fcc compounds M(4)N (M=Fe, Cr, Ag, etc.) and the expanded fcc nitrogen S-phase shows deep infiltration of 6 ± 1 μm, and provides bactericidal activity against both Gram-negative Escherichia coli NCTC 10418 and Gram-positive Staphylococcus epidermidis NCTC 11047 of over 97% and 90%, respectively, within 6h. The presence of silver in the surface before and after scratching under a progressive load applied up to 60 N using a diamond stylus was confirmed by WDS.

Development of an antimicrobial resin--a pilot study

OBJECTIVES

To demonstrate that silver nanoparticles (AgNPs) could be synthesized in situ in acrylic dental resins.

METHODS

Light-cure (LC; bisphenol A glycidyl methacrylate, tetraethyleneglycol dimethacrylate, bisphenol A ethoxylate dimethacrylate blend) and chemical-cure systems (CC; orthodontic denture resin) were used to synthesize AgNPs using different concentrations of Ag benzoate (AgBz).

RESULTS

Rockwell hardness for LC resins showed that resins could be cured with up to 0.15% AgBz, while the hardness of CC resins were unaffected in the concentrations tested. UV-Vis spectroscopy and transmission electron microscopy confirmed the presence of AgNPs in both LC and CC resins. Generally, CC resins had better distribution of and much smaller AgNPs as compared to LC resins overall. In some samples, especially in LC resins, nanoclusters were visible. An in vitro release study over four-weeks showed that CC resins released the most Ag(+) ions, with release detected in all samples. However, LC resins only released Ag(+) ions when AgBz concentration was greater than 0.1% (w/w). AgNP-loaded CC resins made with 0.2 and 0.5% (w/w) AgBz were tested for antibacterial activity in vitro against Streptococcus mutans, and results showed 52.4% and a 97.5% bacterial inhibition, respectively. Further work is now warranted to test mechanical properties and to optimize the initiator system to produce commercially useful dental and medical resins.

SIGNIFICANCE

Success in this work could lead to a series of antimicrobial medical and dental biomaterials that can prevent secondary caries and infection of implants.

Recent progress in inorganic and composite coatings with bactericidal capability for orthopaedic applications

This review covers the most recent developments of inorganic and organic-inorganic composite coatings for orthopedic implants, providing the interface with living tissue and with potential for drug delivery to combat infections. Conventional systemic delivery of drugs is an inefficient procedure that may cause toxicity and may require a patient's hospitalization for monitoring. Local delivery of antibiotics and other bioactive molecules maximizes their effect where they are required, reduces potential systemic toxicity and increases timeliness and cost efficiency. In addition, local delivery has broad applications in combating infection-related diseases. Polymeric coatings may present some disadvantages. These disadvantages include limited chemical stability, local inflammatory reactions, uncontrolled drug-release kinetics, late thrombosis and restenosis. As a result, embedding of bioactive compounds and biomolecules within inorganic coatings (bioceramics, bioactive glasses) is attracting significant attention. Recently nanoceramics have attracted interest because surface nanostructuring allows for improved cellular adhesion, enhances osteoblast proliferation and differentiation, and increases biomineralization. Organic-inorganic composite coatings, which combine biopolymers and bioactive ceramics that mimick bone structure to induce biomineralization, with the addition of biomolecules, represent alternative systems and ideal materials for "smart" implants. In this review, emphasis is placed on materials and processing techniques developed to advance the therapeutic use of biomolecules-eluting coatings, based on nanostructured ceramics. One part of this report is dedicated to inorganic and composite coatings with antibacterial functionality.

FROM THE CLINICAL EDITOR

Inorganic and composite nanotechnology-based coating methods have recently been developed for orthopedic applications, with the main goal to provide bactericide and other enhanced properties, which may result in reduced need for pharmaceutical interventions and overall more cost effective orthopedic procedures. This review discusses key aspects of the above developments.

Nano-Ag-loaded hydroxyapatite coatings on titanium surfaces by electrochemical deposition

Hydroxyapatite (HA) coatings on titanium (Ti) substrates have attracted much attention owing to the combination of good mechanical properties of Ti and superior biocompatibility of HA. Incorporating silver (Ag) into HA coatings is an effective method to impart the coatings with antibacterial properties. However, the uniform distribution of Ag is still a challenge and Ag particles in the coatings are easy to agglomerate, which in turn affects the applications of the coatings. In this study, we employed pulsed electrochemical deposition to co-deposit HA and Ag simultaneously, which realized the uniform distribution of Ag particles in the coatings. This method was based on the use of a well-designed electrolyte containing Ag ions, calcium ions and l-cysteine, in which cysteine acted as the coordination agent to stabilize Ag ions. The antibacterial and cell culture tests were used to evaluate the antibacterial properties and biocompatibility of HA/Ag composite coatings, respectively. The results indicated the as-prepared coatings had good antibacterial properties and biocompatibility. However, an appropriate silver content should be chosen to balance the biocompatibility and antibacterial properties. Heat treatments promoted the adhesive strength and enhanced the biocompatibility without sacrificing the antibacterial properties of the HA/Ag coatings. In summary, this study provided an alternative method to prepare bioactive surfaces with bactericidal ability for biomedical devices.

Antibacterial activity of dental composites containing zinc oxide nanoparticles

The resin-based dental composites commonly used in restorations result in more plaque accumulation than other materials. Bacterial biofilm growth contributes to secondary caries and failure of resin-based dental composites. Methods to inhibit biofilm growth on dental composites have been sought for several decades. It is demonstrated here that zinc oxide nanoparticles (ZnO-NPs) blended at 10% (w/w) fraction into dental composites display antimicrobial activity and reduce growth of bacterial biofilms by roughly 80% for a single-species model dental biofilm. Antibacterial effectiveness of ZnO-NPs was assessed against Streptococcus sobrinus ATCC 27352 grown both planktonically and as biofilms on composites. Direct contact inhibition was observed by scanning electron microscopy and confocal laser scanning microscopy while biofilm formation was quantified by viable counts. An 80% reduction in bacterial counts was observed with 10% ZnO-NP-containing composites compared with their unmodified counterpart, indicating a statistically significant suppression of biofilm growth. Although, 20% of the bacterial population survived and could form a biofilm layer again, 10% ZnO-NP-containing composites maintained at least some inhibitory activity even after the third generation of biofilm growth. Microscopy demonstrated continuous biofilm formation for unmodified composites after 1-day growth, but only sparsely distributed biofilms formed on 10% ZnO-NP-containing composites. The minimum inhibitory concentration of ZnO-NPs suspended in S. sobrinus planktonic culture was 50 microg mL(-1). ZnO-NP-containing composites (10%) qualitatively showed less biofilm after 1-day-anaerobic growth of a three-species initial colonizer biofilm after being compared with unmodified composites, but did not significantly reduce growth after 3 days.

Antibacterial effects and dissolution behavior of six bioactive glasses

Dissolution behavior of six bioactive glasses was correlated with the antibacterial effects of the same glasses against sixteen clinically important bacterial species. Powdered glasses (<45 microm) were immersed in simulated body fluid (SBF) for 48 h. The pH in the solution inside the glass powder was measured in situ with a microelectrode. After 2, 4, 27, and 48 h, the pH and concentration of ions after removing the particles and mixing the SBF were measured with a normal glass pH electrode and ICP-OES. The bacteria were cultured in broth with the glass powder for up to 4 days, after which the viability of the bacteria was determined. The antibacterial effect of the glasses increased with increasing pH and concentration of alkali ions and thus with increased dissolution tendency of the glasses, but it also depended on the bacterium type. The changes in the concentrations of Si, Ca, Mg, P, and B ions in SBF did not show statistically significant influence on the antibacterial property. Bioactive glasses showed strong antibacterial effects for a wide selection of aerobic bacteria at a high sample concentration (100 mg/mL). The antibacterial effects increased with glass concentration and a concentration of 50 mg/mL (SA/V 185 cm(-1)) was required to generate the bactericidal effects. Understanding the dissolution mechanisms of bioactive glasses is essential when assessing their antibacterial effects.

Effect of calcination on microstructure and antibacterial activity of silver-containing silica coatings

Silver nanoparticle containing silica coatings on soda-lime glass were prepared by the sol-gel process. The effect of thermal densification treatment at different temperatures in the range of 100-700 degrees C on microstructure and antibacterial properties of the coatings were examined. The structural characterization of the coatings was performed by using scanning electron microscope, X-ray diffraction, UV-visible and X-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM). The antibacterial activity of the coatings was determined against Staphylococcus aureus by disk diffusion method. The mechanisms for formation and distribution of silver nanoparticles in the silica matrix with respect to the calcination temperature are discussed, and the correlation between the microstructural properties and antibacterial activity is described. The investigations revealed that silver nanoparticles were mainly in the metallic state during thermal treatments. AFM and XPS examinations proved that silver accumulated on the surface diffuse into glass substrate at higher calcination temperatures. A high level of antibacterial activity was observed for the coatings calcined at 300 degrees C or lower temperatures allowing accommodation of silver on the surface of the coating. Silver diffusion into bulk via ion-exchange with sodium and calcium ions from glass substrate during calcination at higher temperatures (500 or 700 degrees C) resulted in apparent degradation in the antibacterial activity.

Tetrapod-like Zinc Oxide Whisker Enhancement of Resin Composite

There is an increasing demand for composite resins with both strong antibacterial activity and satisfactory mechanical properties. This study tested the hypothesis that the new antibacterial agent tetrapod-like zinc oxide whisker (T-ZnOw) could simultaneously enhance the antibacterial activity and mechanical properties of a two-component composite resin. The antibacterial activities of the materials were assessed by the broth dilution test and direct contact test. Optical microscopy, scanning electron microscopy, and measurements of the flexural strength, compressive strength, and diametral tensile strength were carried out for mechanical characterization. The results revealed that T-ZnOw provided the resin with strong antibacterial activity and improved mechanical properties in all tested groups. However, the antibacterial activity of the resin with 10% T-ZnOw in the powder component significantly decreased after aging treatment. The incorporation of 5% T-ZnOw into the resin powder was optimal to give appropriate antibacterial activity, long-term antibacterial effectiveness, and mechanical properties.

Antibacterial properties of nanostructured silver titanate thin films formed on a titanium plate

Antibacterial activity of various surfaces against methicillin-resistant Staphylococcus aureus (MRSA) was studied. Sodium titanate thin film with a porous network structure and sodium titanate nanotube thin film were formed on titanium surfaces through the reaction of titanium plates with NaOH solutions. Through a silver ion-exchange treatment, Na(+) ions in sodium titanate were exchanged with Ag(+) ions in silver acetate solution, along with the loading of silver nanoparticles on the titanate surfaces. Results of silver ion elution tests of the thin films in fetal bovine serum solution indicate that the release period and the number of silver ions released from the silver titanate thin films can be controlled by altering the crystal structure, nanostructure, and thickness of the titanate phase. The silver ion-exchanged titanate thin films showed high antibacterial activity against MRSA. It was also revealed that although the crystal structure of titanate itself has no large antibacterial effect, higher antibacterial activity mainly arises from the silver ions held in the interlayer spacing of the titanate. The obtained results should aid the development of more convenient and inexpensive antibacterial implants.

Multiple topological isomerism of three-connected networks in silver-based metal-organoboron frameworks

Three 3D Ag-based metal-organoboron frameworks with unprecedented multiple topological isomerism of 3-connected networks were assembled and could control the release of silver ions in biocidal concentration in solution giving excellent antibacterial activities and durability against gram-negative bacteria and gram-positive human pathogens.

Antibacterial and antifungal activity of a soda-lime glass containing copper nanoparticles

A low melting point soda-lime glass powder containing copper nanoparticles with high antibacterial (against gram-positive and gram-negative bacteria) and antifungal activity has been obtained. Sepiolite fibres containing monodispersed copper nanoparticles (d(50) approximately 30 +/- 5 nm) were used as the source of the copper nanoparticles. The observed high activity of the obtained glass powder, particularly against yeast, has been explained by considering the inhibitory synergistic effect of the Ca(2+) lixiviated from the glass on the growth of the colonies.

Bactericidal and biocompatible properties of TiN/Ag multilayered films by ion beam assisted deposition

Nanoscale TiN/Ag multilayered films of thickness 500 nm were synthesized on AISI317 stainless steel by ion beam assisted deposition (IBAD) with the modulation period of 4, 5, 6, 7.5, and 12 nm. The bactericidal and biocompatible properties of TiN/Ag multilayered films were investigated through Gram negative E. coli bacteria and L929 cells (mice fibroblast) as well as human umbilical vein endothelial cells (HUVEC). The results show that the TiN/Ag multilayered films with the modulation period of 7.5 nm possess the strongest bactericidal property. The cytotoxicity grade of TiN/Ag multilayered coating with the modulation periods of 7.5 nm, 12 nm is in 0-1 scope, which indicates this film has no cytotoxicity to L929. HUVEC on TiN/Ag multilayered film grows well and shows good cellularity. Auger electronic spectroscopy reveals the relationship between the structure of TiN/Ag multilayered film and the biomedical properties.

Biological and antibacterial properties of plasma sprayed wollastonite/silver coatings

In this work, plasma sprayed wollastonite/silver coatings were prepared to obtain an implant material having excellent bioactivity, cytocompatibility as well as antibacterial property. The surface characteristics of wollastonite/silver coating were investigated by scanning electron microscopy, energy dispersive spectrometer, atomic absorbance spectroscope and x-ray diffraction. The bioactivity was examined by simulated body fluid soaking test. The antibacterial activity against Escherichia coli was examined by bacterial counting method. And the cytocompatibility and in vitro osteotoxicity was evaluated by alamarBlue Assay using MG-63 osteoblasts. The results showed that silver existed in the wollastonite coating homogeneously as silver oxide and metal silver, which ensured a sustained release of silver for 28 days in deionized water. The loaded silver showed strong inhibition against the growth of Escherichia coli, however exhibited no osteotoxicity. Although the wollastonite/silver coating can not induce apatite formation as quickly as the wollastonite coating did in simulated body fluid, it still exhibited good bioactivity. Therefore, the plasma sprayed wollastonite/silver coating is a promising implant material to be applied in surgery, reducing postoperative infections.

Bone tissue engineering therapeutics: controlled drug delivery in three-dimensional scaffolds

This paper provides an extensive overview of published studies on the development and applications of three-dimensional bone tissue engineering (TE) scaffolds with potential capability for the controlled delivery of therapeutic drugs. Typical drugs considered include gentamicin and other antibiotics generally used to combat osteomyelitis, as well as anti-inflammatory drugs and bisphosphonates, but delivery of growth factors is not covered in this review. In each case reviewed, special attention has been given to the technology used for controlling the release of the loaded drugs. The possibility of designing multifunctional three-dimensional bone TE scaffolds for the emerging field of bone TE therapeutics is discussed. A detailed summary of drugs included in three-dimensional scaffolds and the several approaches developed to combine bioceramics with various polymeric biomaterials in composites for drug-delivery systems is included. The main results presented in the literature are discussed and the remaining challenges in the field are summarized with suggestions for future research directions.