Preliminary study of anti-infective function of a copper-bearing stainless steel

Combatting cyanobacteria: unraveling the potency of 316L-Cu stainless steel in inhibiting Microcystis aeruginosa growth

Harmful algal blooms, particularly those of Microcystis aeruginosa, present significant ecological and health risks. To address this issue, this study utilized a custom static algal growth assessment apparatus to investigate the anti-algal performance of a copper-alloyed 316L stainless steel (SS), named 316L-Cu SS. This material was compared with traditional 316L SS, which is widely utilized in freshwater systems for its corrosion resistance. Algal growth dynamics were monitored through optical density (OD) and chlorophyll A concentration measurements. Notably, 316L-Cu SS exhibited superior inhibitory effects on Microcystis aeruginosa growth compared to 316L SS and control groups. Inductively coupled plasma mass spectrometry (ICP-MS) confirmed that the copper ion release from 316L-Cu SS played a critical role in this algal suppression, which interfered with photosynthesis, induced oxidative stress, and damaged algal cell membranes. In contrast, other metal ions (Ni, Cr, Fe) had a negligible impact on algal growth. The study highlights 316L-Cu SS as a promising material for mitigating harmful algal blooms, thereby offering potential benefits for both aquatic ecosystem conservation and public health protection.

Novel Antibacterial Metals as Food Contact Materials: A Review

Food contamination caused by microorganisms is a significant issue in the food field that not only affects the shelf life of food, but also threatens human health, causing huge economic losses. Considering that the materials in direct or indirect contact with food are important carriers and vectors of microorganisms, the development of antibacterial food contact materials is an important coping strategy. However, different antibacterial agents, manufacturing methods, and material characteristics have brought great challenges to the antibacterial effectiveness, durability, and component migration associated with the use security of materials. Therefore, this review focused on the most widely used metal-type food contact materials and comprehensively presents the research progress regarding antibacterial food contact materials, hoping to provide references for exploring novel antibacterial food contact materials.

Facile and versatile strategy for fabrication of highly bacteriostatic and biocompatible SLA-Ti surfaces with the regulation of Mg/Cu coimplantation ratio for dental implant applications

The low bactericidal activity and poor osteogenic activity of Ti limit the use of this metal in dental implants by increasing the risk of their periimplantitis-induced failure. To address this problem, we herein surface-modify biomedical Ti through the plasma immersion coimplantation of Mg and Cu ions and examine the physicochemical properties and bio-/hemocompatibility of the resulting materials as well as their activity against periimplantitis-causing bacteria, namely Streptococcus mutans and Porphyromonas gingivalis. The reactive oxygen species release (ROS) was assessed via the 2'7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assay. The best-performing sample Mg/Cu（8/10）-Ti promotes cell proliferation and initial cell adhesion while exhibiting high hydrophilicity, outstanding activity against the aforementioned pathogens, and good bio-/hemocompatibility. Additionally, higher levels of cellular ROS generation in S. mutans and P. gingivalis could provide insight into the antibacterial mechanisms involved in Mg/Cu（8/10）-Ti. Thus, Mg/Cu coimplantation is concluded to endow the Ti surface with high bacteriostatic activity and biocompatibility, paving the way to the widespread use of Ti-based dental implants.

Enhanced Corrosion Resistance and Biological Properties of Ultrafine-Grained Ti15Zr5Cu Alloy

Titanium alloys are widely used in the biomedical field. To ensure their strength meets requirements in clinics, medical titanium alloys are generally alloyed with toxic Al and/or V elements, hence ensuring their long-term biological safety after implantation is a challenge. In our previous research, we developed an ultrafine-grained Ti15Zr5Cu alloy without toxic elements while its mechanical properties were at the same level with the most widely used Ti6Al4V alloy. In order to promote the clinical application of the ultrafine-grained Ti15Zr5Cu alloy, herein we have systematically studied the hot deformation behaviors of the material as well as evaluated its corrosion resistance and biological properties. Results showed that when the as-quenched Ti15Zr5Cu alloy deformed at 0.05 ≤ ε˙ ≤ 1, 730 °C ≤ T ≤ 750 °C, it not only possessed good workability but also can be converted into an equiaxed ultrafine-grained microstructure. Moreover, the material also exhibited better corrosion resistance, antibacterial properties and biocompatibility than the Ti15Zr alloy and the commercial pure Ti. The results of the present study help lay a foundation for the development of a new generation of medical titanium alloys.

Nutrient alloying elements in biodegradable metals: a review

As a new generation of biomedical metallic materials, biodegradable metals have become a hot research topic in recent years because they can completely degrade in the human body, thus preventing secondary surgery, and reducing the pain and economic burden for patients. Clinical applications require biodegradable metals with adequate mechanical properties, corrosion resistance, and biocompatibility. Alloying is an important method to create biodegradable metals with required and comprehensive performances. Since nutrient elements already have important effects on various physiological functions of the human body, the alloying of nutrient elements with biodegradable metals has attracted much attention. The present review summarizes and discusses the effects of nutrient alloying elements on the mechanical properties, biodegradation behavior, and biocompatibility of biodegradable metals. Moreover, future research directions of biodegradable metals with nutrient alloying elements are suggested.

Evaluation of radiation interaction parameters of some shape memory alloys

In this study, effective atomic number (Zeff), atomic (σta) and electronic cross section (σte) values of some shape memory alloys (SMA) were calculated at energies 5.9, 6.1, 8, 11.2, 25, 59.543, 75, 112, 149 keV. It has been observed that the obtained values of the calculated parameters vary depending on the photon intensity, chemical constitution and density of the alloys. Calculations were made using the WinXCom program and the graph of the change according to the energy of the obtained results was drawn. The results of this study are thought to be beneficial in the application of various fields.

The inhibition effects of Cu and Ni alloying elements on corrosion of HSLA steel influenced by Halomonas titanicae

Halomonas titanicae accelerated steel corrosion by dissimilatory Fe(III) reduction under anaerobic environments, and their adhesion was the key to achieving extracellular electron transfer between cells and Fe(III). This work investigated the inhibition effects of Cu and Ni alloying elements on corrosion of high strength low alloy (HSLA) steel affected by H. titanicae. It was found that both the addition of Cu (1.3%) and high content of Ni (7.2%) brought better corrosion resistance than the steel containing 4.8% Ni via decreasing the amount of sessile bacterial cells. And the inhibition efficiency of Cu with the lower content was stronger than that of Ni with the higher content. Biofilm inhibition mechanisms varied from Cu to Ni alloying elements, and the former was achieved via bactericidal Cu ions released from steel. While for the HSLA steel with high Ni content, the formation of nickel oxides including NiFe₂O₄ and Ni(OH)₂ refined the grains of corrosion products and decreased the bacterial attachment.

Copper-Loaded Biodegradable Bone Wax with Antibacterial and Angiogenic Properties in Early Bone Repair

Traditional bone wax has lots of shortcomings such as the risk of infection and inflammation and the ability to hinder osteogenesis that limit its clinical applications. In this study, we designed a novel biodegradable bone wax with desirable angiogenic and antibacterial ability and low foreign body reaction by mixing calcium sulfate, poloxamer, and cupric ions. To evaluate its biocompatibility and angiogenetic effect in vitro, we cultured human umbilical vein endothelial cells (HUVECs) with the indicated bone wax to observe cell viability and vessel-like tubular formation. The bone wax was then implanted in a critical-sized bone defect rat model for 4 and 8 weeks to successfully stimulate angiogenesis in vivo. Finally, the bone wax extract was incubated with Gram-positive Staphylococcus aureus to confirm its antibacterial ability. The copper-loaded biodegradable bone wax overcomes the drawbacks of traditional bone wax and provides a new approach for the treatment of bone injuries.

Antibacterial metals and alloys for potential biomedical implants

Metals and alloys, including stainless steel, titanium and its alloys, cobalt alloys, and other metals and alloys have been widely used clinically as implant materials, but implant-related infection or inflammation is still one of the main causes of implantation failure. The bacterial infection or inflammation that seriously threatens human health has already become a worldwide complaint. Antibacterial metals and alloys recently have attracted wide attention for their long-term stable antibacterial ability, good mechanical properties and good biocompatibility in vitro and in vivo. In this review, common antibacterial alloying elements, antibacterial standards and testing methods were introduced. Recent developments in the design and manufacturing of antibacterial metal alloys containing various antibacterial agents were described in detail, including antibacterial stainless steel, antibacterial titanium alloy, antibacterial zinc and alloy, antibacterial magnesium and alloy, antibacterial cobalt alloy, and other antibacterial metals and alloys. Researches on the antibacterial properties, mechanical properties, corrosion resistance and biocompatibility of antibacterial metals and alloys have been summarized in detail for the first time. It is hoped that this review could help researchers understand the development of antibacterial alloys in a timely manner, thereby could promote the development of antibacterial metal alloys and the clinical application.

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This paper focuses the recent development of several antibacterial metals and alloys as biomedical materials.

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The possible antibacterial mechanisms of antibacterial metals and alloys are summarized in this paper.

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This review discusses the feasibility of antibacterial metals and alloys as biomedical implants in the future.

Biological properties of copper-doped biomaterials for orthopedic applications: A review of antibacterial, angiogenic and osteogenic aspects

Copper is an essential trace element required for human life, and is involved in several physiological mechanisms. Today researchers have found and confirmed that Cu has biological properties which are particularly useful for orthopedic biomaterials applications such as implant coatings or biodegradable filler bone substitutes. Indeed, Cu exhibits antibacterial functions, provides angiogenic ability and favors osteogenesis; these represent major key points for ideal biomaterial integration and the healing process that follows. The antibacterial performances of copper-doped biomaterials present an interesting alternative to the massive use of prophylactic antibiotics and help to limit the development of antibiotic resistance. By stimulating blood vessel growth and new bone formation, copper contributes to the improved bio-integration of biomaterials. This review describes the bio-functional advantages offered by Cu and focuses on the antibacterial, angiogenic and osteogenic properties of Cu-doped biomaterials with potential for orthopedic applications.

An Antibacterial Strategy of Mg-Cu Bone Grafting in Infection-Mediated Periodontics

Periodontal diseases are mainly the results of infections and inflammation of the gum and bone that surround and support the teeth. In this study, the alveolar bone destruction in periodontitis is hypothesized to be treated with novel Mg-Cu alloy grafts due to their antimicrobial and osteopromotive properties. In order to study this new strategy using Mg-Cu alloy grafts as a periodontal bone substitute, the in vitro degradation and antibacterial performance were examined. The pH variation and Mg²⁺ and Cu²⁺ release of Mg-Cu alloy extracts were measured. Porphyromonas gingivalis (P. gingivalis) and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), two common bacteria associated with periodontal disease, were cultured in Mg-Cu alloy extracts, and bacterial survival rate was evaluated. The changes of bacterial biofilm and its structure were revealed by scanning electron microscopy (SEM) and transmission electronic microscopy (TEM), respectively. The results showed that the Mg-Cu alloy could significantly decrease the survival rates of both P. gingivalis and A. actinomycetemcomitans. Furthermore, the bacterial biofilms were completely destroyed in Mg-Cu alloy extracts, and the bacterial cell membranes were damaged, finally leading to bacterial apoptosis. These results indicate that the Mg-Cu alloy can effectively eliminate periodontal pathogens, and the use of Mg-Cu in periodontal bone grafts has a great potential to prevent infections after periodontal surgery.

A Novel Design to Enhance the Mechanical Properties in Cu-Bearing Antibacterial Stainless Steel

A novel method based on nano-scale precipitation hardening has been studied to strengthen copper-bearing ferrite antibacterial stainless steel. Bimodal precipitations can be observed after antibacterial annealing and low temperature aging treatment, which are large rod-shaped precipitates and nano-sized spherical precipitates, respectively. Due to two different morphological precipitates, the strength of the material is significantly improved without sacrificing formability, and at the same time, the excellent antibacterial properties remain. Under low temperature aging treatment, there is no obvious evidence to show the segregation at the interface between the rod-shaped copper precipitation and the matrix due to the low segregation coefficient of copper. The nano-sized copper precipitation uniformly nucleated and distributed on the matrix. The optimized heat treatment process is antibacterial annealing at 800 °C for half an hour followed by one-hour-aging treatment at 550 °C.

Pirometaxine™ (Narlisim™) in pediatric nasal congestion: a retrospective study

BACKGROUND

Nasal congestion represents a troublesome health issue which is especially and invalidating in children. Effective nasal drugs, such as sympathomimetic drugs, are usually forbidden in children under 12 years of age because of their potential systemic adverse effects. Hypertonic nasal physiological solutions have recently been successfully used to decongest nasal mucosa in children: its mechanical activity has been universally recognized as safe and effective and it represents a well-established, useful treatment in children.

METHODS

We have retrospectively analyzed a case series of 40 children treated for 4 days (96 hours) with a new class 1s medical device nasal hypertonic spray containing Pirometaxine™ (Narlisim™) in outpatient affected by nasal congestion due to common cold. Every child was evaluated on a 3-point symptom assessment scale (0: no symptom; 1: mild symptom; 2: moderate symptom; 3: severe symptom) at the beginning of the trial (T0) and after 48 (T1) and 96 hours (T2). The symptoms assessed were nasal obstruction, nasal secretion, headache, flash of cold, pharyngodynia, cough, and sneeze.

RESULTS

The results, in terms of short-term efficacy to control nasal obstruction (T1 vs. T0: P<0.0001; T2 vs. T0: P<0.0001), nasal secretion (T1 vs. T0: P<0.0001; T2 vs. T0: P<0.0001) and all the symptoms related to common cold have supported the efficacy of this hypertonic nasal solution. No adverse events have been pointed out during the trial supporting the safety of this new nasal hypertonic approach.

CONCLUSIONS

The absence of adverse events after 48-96 hours along with the short-term effectiveness of this new treatment seems to represent a new, safe option to treat children affected by nasal congestion secondary to common cold. Considering the current lack of safe treatments for children under 12 years of age, Narlisim™ can be considered as a useful short-term option to control nasal congestion in children.

In vitro study on cytocompatibility and osteogenesis ability of Ti-Cu alloy

Titanium implants easily suffer bacteria-related infections in clinic due to their inherent lack of self-protection ability. Therefore, a novel Ti-Cu alloy with good antibacterial activity has been developed as a new kind of implant material. This study focuses on a systematic evaluation of both cytocompatibility and osteogenesis activity of the Ti-Cu alloy in vitro. It was revealed that an addition of 5% Cu into pure Ti would not cause any negative effect on osteoblasts adhesion, proliferation and apoptosis cultured with Ti-Cu alloy. In addition, Ti-Cu alloy could significantly promote the osteogenic differentiation of MG 63 cells by upregulating the osteogenesis-related gene expressions including alkaline phosphatase (ALP), Collagen I (Colla I), osteopontin (OPN) and osteocalcin (OCN). These promising results suggest that the Ti-Cu alloy has great potential to be used as a multi-functional titanium implant for clinical applications.

Degradable magnesium-based alloys for biomedical applications: The role of critical alloying elements

Magnesium-based alloys exhibit biodegradable, biocompatible and excellent mechanical properties which enable them to serve as ideal candidate biomedical materials. In particular, their biodegradable ability helps patients to avoid a second surgery. The corrosion rate, however, is too rapid to sustain the healing process. Alloying is an effective method to slow down the corrosion rate. However, currently magnesium alloys used as biomaterials are mostly commercial alloys without considering cytotoxicity from the perspective of biosafety. This article comprehensively reviews the status of various existing and newly developed degradable magnesium-based alloys specially designed for biomedical application. The effects of critical alloying elements, compositions, heat treatment and processing technology on the microstructure, mechanical properties and corrosion resistance of magnesium alloys are discussed in detail. This article covers Mg-Ca based, Mg-Zn based, Mg-Sr based, Mg-RE based and Mg-Cu-based alloy systems. The novel methods of fabricating Mg-based biomaterials and surface treatment on Mg based alloys for potential biomedical applications are summarized.

Antibacterial TiCu/TiCuN Multilayer Films with Good Corrosion Resistance Deposited by Axial Magnetic Field-Enhanced Arc Ion Plating

In order to develop a novel kind of antibacterial Cu-containing TiN film with good corrosion resistance, impressive mechanical properties, and low cytotoxicity, three differently designed multilayer films of TiCu/TiCuN multilayer (M1, M2, M3) were deposited on the surface of 316L stainless steel surface using the axial magnetic field-enhanced arc ion plating (AMFE-ARP) method, in which the interlayer of TiCu was first introduced for Cu-containing TiN film in order to improve comprehensive properties, especially the corrosion resistance of the film. The performance of the TiCu/TiCuN multilayer films was compared with that of the two single layers, TiN and TiCuN, which were deposited by the same method and the same total deposition time. The results indicated that the TiCu/TiCuN multilayer film of M2 revealed the best comprehensive corrosion resistance with low electric current values, high pitting potential, and high polarization resistance due to the proper thickness of TiCu interlayers and larger number of TiCu/TiCuN bilayers. In addition, the TiCu/TiCuN multilayer film of M2 also possesses comparable mechanical properties, excellent antibacterial and antibiofilm abilities, as well as good biocompatibility. Consequently, the antibacterial TiCu/TiCuN multilayer films with good corrosion resistance deposited by using the axial magnetic field-enhanced arc ion plating (AMFE-ARP) method are promising for application in biomedical antibacterial film for implants.

The current trends of Mg alloys in biomedical applications-A review

Magnesium (Mg) has emerged as an ideal alternative to the permanent implant materials owing to its enhanced properties such as biodegradation, better mechanical strengths than polymeric biodegradable materials and biocompatibility. It has been under investigation as an implant material both in cardiovascular and orthopedic applications. The use of Mg as an implant material reduces the risk of long-term incompatible interaction of implant with tissues and eliminates the second surgical procedure to remove the implant, thus minimizes the complications. The hurdle in the extensive use of Mg implants is its fast degradation rate, which consequently reduces the mechanical strength to support the implant site. Alloy development, surface treatment, and design modification of implants are the routes that can lead to the improved corrosion resistance of Mg implants and extensive research is going on in all three directions. In this review, the recent trends in the alloying and surface treatment of Mg have been discussed in detail. Additionally, the recent progress in the use of computational models to analyze Mg bioimplants has been given special consideration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1970-1996, 2019.

Evaluation of promoting effect of a novel Cu-bearing metal stent on endothelialization process from in vitro and in vivo studies

Drug eluting stents (DES) have been extensively applied nowadays and reduce the incidence of in-stent restenosis (ISR) greatly as compared with bare metal stents (BMS). However, the development of DES is hindered by the risk of late stent thrombosis (LST) due to delayed re-endothelialization, while endothelialization is an important process related to ISR and LST after implantation. 316L is a traditional stent material without bioactivity and have a high risk of ISR. Cu is recognized for angiogenesis stimulation in these years. Hence a copper bearing 316L stainless steel (316L-Cu) was prepared and evaluated about its effect on endothelialization in this paper. Compared with traditional 316L, it was proved that 316L-Cu increased the proliferation of co-cultured human umbilical vein endothelial cells (HUVECs) at first day. Moreover, HUVECs stretched better on the surface of 316L-Cu. It also improved the expression of angiogenesis related genes and tube formation ability in vitro. 316L-Cu-BMS, DES and 316L-BMS were implanted in swine to evaluate the re-endothelialization ability in vivo. And 316L-Cu-BMS showed the best effect on endothelialization with good biosafety. Consequently, 316L-Cu is a kind of promising BMS material for coronary field.

Anti-fibrotic function of Cu-bearing stainless steel for reducing recurrence of urethral stricture after stent implantation

Recurrent stenosis is the main reason inducing the failure of urethral stricture treatment. Our previous study has found that the 316L type Cu bearing stainless steel (316L-Cu SS) showed antimicrobial activity and anti-encrustation performance when it was used for relieving urethral obstructer. However, whether it can reduce the occurrence of fibrosis or not, we need further investigation to compare the cellular and molecular responses of human urethral scar fibroblast cells (USFCs) on 316L-Cu SS and medical grade 316L stainless (316L SS, as a control). [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4- sulfophenyl)- 2H-tetrazolium (MTS) and Transwell were used to assess the cellular responses, which confirmed that 316L-Cu SS could inhibit proliferation and migration of USFCs. Molecular expressions of fibrosis were evaluated by western blot, real-time quantitative polymerase chain reaction (qPCR), and Cu/Zn superoxide dismutase (CuZnSOD) measurement. The results indicated that up-regulating of CuZnSOD attenuated the transforming growth factor-β1 expression and phosphorylation of Smad3 after exposure to 316L-Cu SS. Besides, the content of collagen type I (COL1) and collagen type III (COL3) secreting into the culture medium measured by enzyme-linked immunosorbent assay were in accord with the results of messenger ribonucleic acids. Both of them exhibited lower levels of COL1/COL3 exposure to 316L-Cu SS, demonstrating the inhibitory performance of 316L-Cu SS against fibrosis. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2019-2028, 2018.

Antibacterial activity, corrosion resistance and wear behavior of spark plasma sintered Ta-5Cu alloy for biomedical applications

Tantalum has been widely used in orthopedic and dental implants. However, the major barrier to the extended use of such medical devices is the possibility of bacterial adhesion to the implant surface which will cause implant-associated infections. To solve this problem, bulk Ta-5Cu alloy has been fabricated by a combination of mechanical alloying and spark plasma sintering. The effect of the addition of Cu on the hardness, antibacterial activity, cytocompatibility, corrosion resistance and wear performance was systematically investigated. The sintered Ta-5Cu alloy shows enhanced antibacterial activity against E. Coli due to the sustained release of Cu ions. However, the addition of Cu would produce slight cytotoxicity and decrease corrosion resistance of Ta. Furthermore, pin-on-disk wear tests show that Ta-5Cu alloy has a much lower coefficient of friction but a higher wear rate and shows a distinct wear mode from that of Ta upon sliding against stainless steel 440C. Wear-induced plastic deformation leads to elongation of Ta and Cu grains along the sliding direction and nanolayered structures were observed upon approaching the sliding surface. The presence of hard oxides also shows a profound effect on the plastic flow of the base material and results in localized vortex patterns. The obtained results are expected to provide deep insights into the development of novel Ta-Cu alloy for biomedical applications.

Investigation of Structural, Compositional and Anti-Microbial Properties of Copper Thin Film Using Direct Current Magnetron Sputtering for Surgical Instruments

Surgical instruments and other bioimplant devices, owing to their importance in the biomedical industry require high biocompatibility to be used in the human body. Nevertheless, issues of compatibility, bacterial infections are quite common in such devices. Hence development of surface coatings on various substrates for implant applications is a promising technique to combat the issues arising in these implant materials. The present investigation aims at coating copper on stainless steel substrate using DC Magnetron sputtering which is used to achieve film of required thickness (0.5–8[Formula: see text][Formula: see text]m). The deposition pressure, substrate temperature, power supply, distance between the specimen and target are optimized and maintained constant, while the sputtering time (30–110[Formula: see text]min) is varied. The sputtered copper thin film’s morphology, composition are characterized by SEM and EDAX. X-ray diffraction analysis shows copper oriented on (111) and (002) and copper oxide on (111) planes. The contact angle of copper thin film is 92[Formula: see text] while AISI 316L shows 73[Formula: see text]. The antimicrobial studies carried in Staphylococcus aureus, Escherichia Coli, Klebsiella pneumonia and Candida albicans show that the maximum reduction was seen upto 35, 26, 54, 39[Formula: see text]CFU/mL, respectively after 24[Formula: see text]h. The cell viability is studied by MTT assay test on Vero cell line for 24[Formula: see text]h, 48[Formula: see text]h and 72[Formula: see text]h and average cell viability is 43.85%. The copper release from the thin film to the culture medium is 6691[Formula: see text][Formula: see text]g/L (maximum) is estimated from AAS studies. The copper coated substrate does not show much reaction with living Vero cells whereas the bacteria and fungi are found to be destroyed.

Antibacterial effect of copper-bearing titanium alloy (Ti-Cu) against Streptococcus mutans and Porphyromonas gingivalis

Formation of bacterial biofilms on dental implant material surfaces (titanium) may lead to the development of peri-implant diseases influencing the long term success of dental implants. In this study, a novel Cu-bearing titanium alloy (Ti-Cu) was designed and fabricated in order to efficiently kill bacteria and discourage formation of biofilms, and then inhibit bacterial infection and prevent implant failure, in comparison with pure Ti. Results from biofilm based gene expression studies, biofilm growth observation, bacterial viability measurements and morphological examination of bacteria, revealed antimicrobial/antibiofilm activities of Ti-Cu alloy against the oral specific bacterial species, Streptococcus mutans and Porphyromonas gingivalis. Proliferation and adhesion assays with mesenchymal stem cells, and measurement of the mean daily amount of Cu ion release demonstrated Ti-Cu alloy to be biocompatible. In conclusion, Ti-Cu alloy is a promising dental implant material with antimicrobial/antibiofilm activities and acceptable biocompatibility.

An investigation of the antibacterial ability and cytotoxicity of a novel cu-bearing 317L stainless steel

In order to solve the challenging problem of microbial infections caused by microorganisms on medical implants, it is imperative to develop novel antimicrobial biomaterials. This work demonstrated that 317L-Cu stainless steel (SS), created by adding copper through a solution and aging heat treatment process, exhibited good antibacterial properties against staphylococcus aureus, achieving 2 log reduction of planktonic cells after 5 days of incubation. In this study, the antibacterial test was performed using the plate count method, the fluorescence cell staining method and the quantitative polymerase chain reaction (qPCR) method. It is well known that a high concentration of copper ion can lead to cytotoxicity. This work explored the cytotoxicity of 317L-Cu SS through real-time cell analysis (RTCA). Experimental results demonstrated that the 317L-Cu SS possessed a satisfactory antibacterial ability against S. aureus, and the antibacterial rate based on the reduction of sessile cell count reached 98.3% after 24-hour treatment. The bacterial adhesion and the biofilm thickness were considerably reduced by the 317L-Cu SS. The results of RTCA suggested that 317L-Cu SS did not introduce cytotoxicity to mouse cells, indicating its suitability as a medical implant material.

Biodegradable Mg-Cu alloys with enhanced osteogenesis, angiogenesis, and long-lasting antibacterial effects

A series of biodegradable Mg-Cu alloys is designed to induce osteogenesis, stimulate angiogenesis, and provide long-lasting antibacterial performance at the same time. The Mg-Cu alloys with precipitated Mg2Cu intermetallic phases exhibit accelerated degradation in the physiological environment due to galvanic corrosion and the alkaline environment combined with Cu release endows the Mg-Cu alloys with prolonged antibacterial effects. In addition to no cytotoxicity towards HUVECs and MC3T3-E1 cells, the Mg-Cu alloys, particularly Mg-0.03Cu, enhance the cell viability, alkaline phosphatase activity, matrix mineralization, collagen secretion, osteogenesis-related gene and protein expressions of MC3T3-E1 cells, cell proliferation, migration, endothelial tubule forming, angiogenesis-related gene, and protein expressions of HUVECs compared to pure Mg. The favorable osteogenesis and angiogenesis are believed to arise from the release of bioactive Mg and Cu ions into the biological environment and the biodegradable Mg-Cu alloys with osteogenesis, angiogenesis, and long-term antibacterial ability are very promising in orthopedic applications.

In vitro study on an antibacterial Ti-5Cu alloy for medical application

Health of human beings is subjected to severe threats from the spread of harmful bacteria and the implant-associated infection remains a serious problem in clinic. In this study, a copper-bearing antibacterial titanium alloy, Ti-5Cu, has been developed for dental and orthopedic implant applications. The microstructure, mechanical property, electrochemical corrosion behavior, in vitro antibacterial performance, cytocompatibility and hemocompatibility of the alloy are systematically investigated. The results reveal that the Ti-5Cu alloy which consists of α-phase matrix and intermetallic compound Ti2Cu not only possesses strong antibacterial activity against both E. coli and S. aureus, but also exhibits better mechanical properties than the commercial pure titanium. It is confirmed that the release of trace amount of Cu ions from the alloy plays an important role in killing bacteria. In spite of the ion release, Ti-5Cu alloy still reveals excellent corrosion resistance. Moreover, good cytocompatibility and superior hemocompatibility make Ti-5Cu alloy to be a potential solution that could prevent the peri-implant infection in dental and orthopaedic applications.

Antibacterial activity, osteogenic and angiogenic behaviors of copper-bearing titanium synthesized by PIII&D

Two types of Cu-bearing specimens with or without nanoparticles on Ti surface synthesized by PIII&D showed disparate biological responses.

Biocompatibility of antibacterial Ti-Cu sintered alloy: in vivo bone response

Ti-10Cu sintered alloy has shown very strong in vitro and in vivo antibacterial property and in vitro cell compatibility. In this paper, Ti-10Cu implant (Ti-Cu group) and commercial pure Ti implant (cp-Ti group) were implanted in rabbit femurs to investigate in vivo bone response to the Ti-10Cu alloy. X-ray photo, fluorescent microscopy, routine pathological examination and immunohistochemistry have been used to analyze bone growth, mineral apposition rate (MAR), bone implant contact (BIC), BMP-2 expression and TGF-β1 expression. In both Ti-Cu and cp-Ti groups, new bone tissue was found at bone/implant interfaces 4 weeks postimplantation and completely filled the interfaces gap bone 12 weeks postimplantation. A significant MOD value in BMP-2 expression was observed at week 1 and week 4 in the Ti-Cu group with lower values of week 2 and 3 in both groups, which indicated strong positive activity. MOD value in TGF-β1 expression decreased with the extension of implantation. However, no difference can be found in MAR, BIC and TGF-β1 expression between the two groups at all intervals. It was deduced that Ti-Cu alloy exhibited as good bone response as cp-Ti. The good bone compatibility suggests that Ti-10Cu alloy might have potential application in orthopedic surgery and dental implant.

Laboratory investigation of the microbiologically influenced corrosion (MIC) resistance of a novel Cu-bearing 2205 duplex stainless steel in the presence of an aerobic marine Pseudomonas aeruginosa biofilm

The microbiologically influenced corrosion (MIC) resistance of a novel Cu-bearing 2205 duplex stainless steel (2205 Cu-DSS) against an aerobic marine Pseudomonas aeruginosa biofilm was investigated. The electrochemical test results showed that Rp increased and icorr decreased sharply after long-term immersion in the inoculation medium, suggesting that 2205 Cu-DSS possessed excellent MIC resistance to the P. aeruginosa biofilm. Fluorescence microscope images showed that 2205 Cu-DSS possessed a strong antibacterial ability, and its antibacterial efficiency after one and seven days was 7.75% and 96.92%, respectively. The pit morphology comparison after 14 days between 2205 DSS and 2205 Cu-DSS demonstrated that the latter showed a considerably reduced maximum MIC pit depth compared with the former (1.44 μm vs 9.50 μm). The experimental results suggest that inhibition of the biofilm was caused by the copper ions released from the 2205 Cu-DSS, leading to its effective mitigation of MIC by P. aeruginosa.

Osteogenic ability of Cu-bearing stainless steel

A newly developed copper-bearing stainless steel (Cu-SS) by directly immobilizing proper amount of Cu into a medical stainless steel (317L SS) during the metallurgical process could enable continuous release of trace amount of Cu(2+) ions, which play the key role to offer the multi-biofunctions of the stainless steel, including the osteogenic ability in the present study. The results of in vitro experiments clearly demonstrated that Cu(2+) ions from Cu-SS could promote the osteogenic differentiation by stimulating the Alkaline phosphatase enzyme activity and the osteogenic gene expressions (Col1a1, Opn, and Runx2), and enhancing the adhesion and proliferation of osteoblasts cultured on its surface. The in vivo test further proved that more new bone tissue formed around the Cu-SS implant with more stable bone-to-implant contact in comparison with the 317L SS. In addition, Cu-SS showed satisfied biocompatibility according to the results of in vitro cytotoxicity and in vivo histocompatibility, and its daily released amount of Cu(2+) ions in physiological saline solution was at trace level of ppb order (1.4 ppb/cm(2) ), which is rather safe to human health. Apart from these results, it was also found that Cu-SS could inhibit the happening of inflammation with lower TNF-α expression in the bone tissue post implantation compared with 317L SS. In addition to good biocompatibility, the overall findings demonstrated that the Cu-SS possessed obvious ability of promoting osteogenesis, indicating a unique application advantage in orthopedics.

Antibacterial property, angiogenic and osteogenic activity of Cu-incorporated TiO2 coating

Numerous efforts have been made to modify the surface topography and chemical composition of biomedical implants in order to enhance the antibacterial ability and the osteointegration between implants and surrounding bone tissue. In the present work, copper-incorporated TiO₂ coatings were fabricated by combining micro-arc oxidation and hydrothermal treatment together to functionalize the surface of Ti implants. The as-prepared surfaces exhibited a hierarchical structure comprising nanoneedles nearly perpendicular to the microrough surface of the TiO₂ coating. The Cu-loaded TiO₂ coating possessed strong antimicrobial ability against Gram-negative Escherichia coli. In vitro cytocompatibility evaluation suggests that no significant cytotoxicity appeared on the Cu-incorporated TiO₂ coating. Furthermore, the addition of the copper element could stimulate the expression of angiogenic genes, including the hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) in rat bone marrow stem cells (BMSCs). Moreover, they tended to undergo osteogenic differentiation, indicated by the up-regulation expression of osteogenic markers and the higher level of alkaline phosphatase activity. This study provides insight for the surface modification of biomedical Ti-based implants. To the best of our best knowledge, this is a successful attempt for the first time to combine micro-arc oxidation and hydrothermal treatment to introduce copper nutrient element to functionalize Ti-based implant surfaces with enhanced angiogenesis potential, osteostimulation and antimicrobial properties that can better meet clinical needs.

Effect of the La alloying addition on the antibacterial capability of 316L stainless steel

316L stainless steel is widely used for fashion jewelry but it can carry a large number of bacteria and cause the potential risk of infection since it has no antimicrobial ability. In this paper, La is used as an alloying addition. The antibacterial capability, corrosion resistance and processability of the La-modified 316L are investigated by microscopic observation, thin-film adhering quantitative bacteriostasis, electrochemical measurement and mechanical test. The investigations reveal that the La-containing 316L exhibits the Hormesis effect against Staphylococcus aureus ATCC 25923 and Escherichia coli DH5α, 0.05 wt.% La stimulates their growth, as La increases, the modified 316L exhibits the improved antibacterial effect. The more amount of La is added, the better antibacterial ability is achieved, and 0.42 wt.% La shows excellent antibacterial efficacy. No more than 0.11 wt.% La addition improves slightly the corrosion resistance in artificial sweat and has no observable impact on the processability of 316L, while a larger La content degrades them. Therefore, the addition of La alone in 316L is difficult to obtain the optimal combination of corrosion resistance, antibacterial capability and processability. In spite of that, 0.15 wt.% La around is inferred to be the trade-off for the best overall performance.