Optimal ultrasonic treatment frequency and duration parameters were used to detect the pathogenic bacteria of orthopedic implant-associated infection by ultrasonic oscillation.

INTRUDUCTON: The most accurate method for detecting the pathogen of orthopedic implant-associated infections (OIAIs) is sonication fluid (SF). However, the frequency and duration of ultrasound significantly influence the number and activity of microorganisms. Currently, there is no consensus on the selection of these two parameters. Through this study, the choice of these two parameters is clarified. METHODS: We established five ultrasonic groups (40kHz/10min, 40kHz/5min, 40 kHz/1min, 20kHz/5min, and 10kHz/5min) based on previous literature. OIAIs models were then developed and applied to ultrasound group treatment. Subsequently, we evaluated the efficiency of bacteria removal by conducting SEM and crystal violet staining. The number of live bacteria in the SF was determined using plate colony count and live/dead bacteria staining. RESULTS: The results of crystal violet staining revealed that both the 40kHz/5min group and the 40kHz/10min group exhibited a significantly higher bacterial clearance rate compared to the other groups. However, there was no significant difference between the two groups. Additionally, the results of plate colony count and fluorescence staining of live and dead bacteria indicated that the number of live bacteria in the 40kHz/5min SF group was significantly higher than in the other groups. CONCLUSION: 40kHz/5min ultrasound is the most beneficial for the detection of pathogenic bacteria on the surface of orthopedic implants.

Enhancement of antibacterial properties and biocompatibility of Ti6Al4V by graphene oxide/strontium nanocomposite electrodepositing.

Ti6Al4V is a widely used orthopedic implant material in clinics. Due to its poor antibacterial properties, surface modification is required to prevent peri-implantation infection. However, chemical linkers used for surface modification have generally been reported to have detrimental effects on cell growth. In this work, by optimizing parameters related to electrodeposition, a composite structural coating with graphene oxide (GO) compact films in the inner layer and 35 nm diameter strontium (Sr) nanoparticles in the outer layer was constructed on the surface of Ti6Al4V without using substance harmful to bone marrow mesenchymal stem cells (BMSCs) growth. The antibacterial properties of Ti6Al4V are enhanced by the controlled release of Sr ions and incomplete masking of the GO surface, showing excellent antibacterial activity against Staphylococcus aureus in bacterial culture assays. The biomimetic GO/Sr coating has a reduced roughness of the implant surface and a water contact angle of 44.1°, improving the adhesion, proliferation and differentiation of BMSCs. Observations of synovial tissue and fluid in the joint in an implantation model of rabbit knee also point to the superior anti-infective properties of the novel GO/Sr coating. In summary, the novel GO/Sr nanocomposite coating on the surface of Ti6Al4V effectively prevents surface colonization of Staphylococcus aureus and eliminates local infections in vitro and in vivo.

Effects of different intensities of intermittent pneumatic soft-tissue compression on bone defect repair.

BACKGROUND: To estimate the effects of different intensities of intermittent pneumatic soft-tissue compression on bone defect repair in an animal model. METHODS: Five mm radial bone defect in length was made in 64 mature New Zealand rabbits and all animals randomly assigned into four groups: Group A (control group without compression), Group B (5-7 kPa intensity), Group C (8-10 kPa intensity) and Group D (11-13 kPa intensity). On the fourth day after surgery, their legs were intermittently pneumatic compressed for 4 weeks. The stimulation lasted 30 min every day and the frequency of compression was 15 Hz. New bone formation in 4 groups was evaluated by gross observation, X-ray, Micro-CT, and histological staining at 2 and 4 weeks after surgery. RESULT: There was more new bony callus in the bone defect in group C than in other groups by gross observation and X-ray radiography at 2 and 4 weeks. The Micro-CT results showed more new bony callus, bone trabecula and higher bone mineral density in group C. Fluorescent labeling results showed the speed of new bone formation in Group C was faster than that in other groups, among which the control group had the slowest speed of new bone formation. The result of histology had shown that the trabeculae in bone callus in group C had a regular form, the trabeculae were wide and had a more become osteoblast around them. CONCLUSION: The intermittent pneumatic soft-tissue compression can accelerate new bone formation of bone defects and the optimal intensity is 8-10 kPa for repairing the rabbit radial bone defect.

Effects of cyclic fluid stress at different frequencies on behaviors of cells incubated on titanium alloy.

The orthopedic external fixation is always in dynamic mechanical environment with the somatic movement. We used a self-designed mini oscillator to simulate this condition by providing the reciprocating cyclic fluid stress, and observed the behavioral responses of fibroblasts implanted on titanium alloy plane to the stress at different frequencies, including 0.2 Hz, 0.6 Hz, and 1.0 Hz. We found that the cell angle, shape index and expression of vinculin were mostly biphasic-dependent with the increase of frequency, with peaks at 0.6 Hz. Whereas the cell area, expression of Col-I and α-SMA were mainly affected by the 1.0 Hz stress. Interestingly, 1.0 Hz stress also promoted Col-I expression of bone marrow mesenchymal stem cells (BMSCs), although it did not increase α-SMA. These results reveal that 0.6 Hz stress improves the alignment, polarity and adherence of fibroblasts on titanium alloy substrates, thus improving the sealing of implants; the 1.0 Hz force activates the differentiation of fibroblasts into myofibroblasts and increases collagen produced by stem cells, which probably cause the formation of fibrous capsules around implants.

Graphene coating on the surface of CoCrMo alloy enhances the adhesion and proliferation of bone marrow mesenchymal stem cells.

The objective was to investigate whether a graphene coating could improve the surface bioactivity of a cobalt-chromium-molybdenum-based alloy (CoCrMo). Graphene was produced by chemical vapor deposition and transferred to the surface of the CoCrMo alloy using an improved wet transfer approach. The morphology of the samples was observed, and the adhesion force and stabilization of graphene coating were analyzed by a nanoscratch test and ultrasonication test. In an in vitro study, the adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs) cultured on the samples were quantified via an Alamar Blue assay and cell counting kit-8 (CCK-8) assay. The results showed that it is feasible to apply graphene to modify the surface of a CoCrMo alloy, and the enhancement of the adhesion and proliferation of BMSCs was also shown in the present study. In conclusion, graphene exhibits considerable potential for enhancing the surface bioactivity of CoCrMo alloy.

Graphene modified titanium alloy promote the adhesion, proliferation and osteogenic differentiation of bone marrow stromal cells.

We studied the effects of graphene coating on improving the biological activity of a titanium alloy (Ti6Al4V) widely used in hip and knee joint replacements. The experiments included immunofluorescence staining for observing cellular adhesion, Cell Counting Kit-8 (CCK-8) for evaluating cellular proliferation and reverse transcription-polymerase chain reaction (RT-PCR) for detecting the differentiation of bone marrow stromal cells on different scaffolds. The results showed that G-Ti6Al4V exhibited a higher mean integrated optical density (IOD) for vinculin and resulted in a higher cell proliferation rate and higher osteoblast-specific gene transcription levels. In summary, graphene could be used as a new nanocoating material for Ti6Al4V scaffolds to enhance their surface bioactivity.

Effects of Hindlimb Unweighting on MBP and GDNF Expression and Morphology in Rat Dorsal Root Ganglia Neurons.

With the development of technology and space exploration, studies on long-duration space flights have shown that microgravity induces damage to multiple organs, including the dorsal root ganglia (DRG). However, very little is known about the effects of long-term microgravity on DRG neurons. This study investigated the effects of microgravity on lumbar 5 (L5) DRG neurons in rats using the hindlimb unweighting (HU) model. Male (M) and female (F) Sprague-Dawley rats were randomly divided into M- and F-control (CON) groups and M- and F-HU groups, respectively (n = 10). At the end of HU treatment for 4 weeks, morphological changes were detected. Myelin basic protein (MBP) and degenerated myelin basic protein (dgen-MBP) expressions were analyzed by immunofluorescence and western blot assays. Glial cell line-derived neurotrophic factor (GDNF) protein and mRNA expressions were also analyzed by immunohistochemistry, western blot, and RT-PCR analysis, respectively. Compared with the corresponding CON groups, the HU groups exhibited slightly loose junctions between DRG neurons, some separated ganglion cells and satellite cells, and lightly stained Nissl bodies that were of smaller size and had a scattered distribution. High levels of dgen-MBP and low MBP expressions were appeared and GDNF expressions were significantly decreased in both HU groups. Changes were more pronounced in the F-HU group than in the M-HU group. In conclusion, HU treatment induced damage of L5 DRG neurons, which was correlated with decreased total MBP protein expression, increased dgen-MBP expression, and reduced GDNF protein and mRNA expression. Importantly, these changes were more severe in F-HU rats compared with M-HU rats.

Effects of Nano-hydroxyapatite/Poly(DL-lactic-co-glycolic acid) Microsphere-Based Composite Scaffolds on Repair of Bone Defects: Evaluating the Role of Nano-hydroxyapatite Content.

The aim of the current study was to prepare microsphere-based composite scaffolds made of nano-hydroxyapatite (nHA)/poly (DL-lactic-co-glycolic acid) (PLGA) at different ratios and evaluate the effects of nHA on the characteristics of scaffolds for tissue engineering application. First, microsphere-based composite scaffolds made of two ratios of nHA/PLGA (nHA/PLGA = 20/80 and nHA/PLGA = 50/50) were prepared. Then, the effects of nHA on the wettability, mechanical strength, and degradation of scaffolds were investigated. Second, the biocompatibility and osteoinductivity were evaluated and compared by co-culture of scaffolds with bone marrow stromal stem cells (BMSCs). The results showed that the adhesion, proliferation, and osteogenic differentiation of BMSCs with nHA/PLGA (50/50) were better than those with nHA/PLGA (20/80). Finally, we implanted the scaffolds into femur bone defects in a rabbit model, then the capacity of guiding bone regeneration as well as the in vivo degradation were observed by micro-CT and histological examinations. After 4 weeks' implantation, there was no significant difference on the repair of bone defects. However, after 8 and 12 weeks' implantation, the nHA/PLGA (20/80) exhibited better bone formation than nHA/PLGA (50/50). These results suggested that a proper concentration of nHA in the nHA/PLGA composite should be taken into account when the composite scaffolds were prepared, which plays an important role in the biocompatibility, degradation rate and osteoconductivity.

Analysis of risk factors and development of a nomogram-based prediction model for defective bony non-union.

Objective: To explore risk factors for defective non-union of bone and develop a nomogram-based prediction model for such an outcome. Methods: This retrospective study analysed the case data of patients with defective bony non-unions who were treated at the authors' hospital between January 2010 and December 2020. Patients were divided into the union and non-union groups according to their Radiographic Union Score for Tibia scores 1 year after surgery. Univariate analysis was performed to assess factors related to demographic characteristics, laboratory investigations, surgery, and trauma in both groups. Subsequently, statistically significant factors were included in the multivariate logistic regression analysis to identify independent risk factors. A nomogram-based prediction model was established using statistically significant variables in the multivariate analysis. The accuracy and stability of the model were evaluated using receiver operating characteristic (ROC) and calibration curves. The clinical applicability of the nomogram model was evaluated using decision curve analysis. Results: In total, 204 patients (171 male, 33 female; mean [±SD] age, 39.75 ± 13.00 years) were included. The mean body mass index was 22.95 ± 3.64 kg/m2. Among the included patients, 29 were smokers, 18 were alcohol drinkers, and 21 had a previous comorbid systemic disease (PCSD). Univariate analysis revealed that age, occupation, PCSD, smoking, drinking, interleukin-6, C-reactive protein (CRP), procalcitonin, alkaline phosphatase, glucose, and uric acid levels; blood calcium ion concentration; and bone defect size (BDS) were correlated with defective bone union (all P < 0.05). Multivariate logistic regression analysis revealed that PCSD, smoking, interleukin-6, CRP, and glucose levels; and BDS were associated with defective bone union (all P < 0.05), and the variables in the multivariate analysis were included in the nomogram-based prediction model. The value of the area under the ROC curve for the predictive model for bone defects was 0.95. Conclusion: PCSD, smoking, interleukin-6, CRP, and glucose levels; and BDS were independent risk factors for defective bony non-union, and the incidence of such non-union was predicted using the nomogram. These findings are important for clinical interventions and decision-making.

Effects of sodium hydroxide, sodium hypochlorite, and gaseous hydrogen peroxide on the natural properties of cancellous bone.

Processed xenegeneic cancellous bone represents an alternative to bone autograft. In order to observe the effects of present prion inactivation treatments on the natural properties of xenogeneic cancellous bones, we treated bovine bone granules with sodium hydroxide (NaOH), sodium hypochlorite (NaOCl), and gaseous hydrogen peroxide (gH2 O2 ) respectively in this study. The microstructure, composition, and mineral content of the granules were evaluated by scanning electron micrograph, energy dispersive X-ray spectroscopy, ash analysis, and micro-computed tomography. The biomechanical property was analyzed by a materials testing machine. The cytocompatibility was evaluated by using a mouse fibroblast cell line (3T3). The microstructure, organic content, and mechanical strength were dramatically altered at the surface of bone in both NaOH- and NaOCl-treated groups, but not in the gH2 O2 -treated group. Compared with the gH2 O2 -treated group, attachment and proliferation of 3T3 were reduced in either NaOH- or NaOCl-treated groups. As the consequence, gH2 O2 treatment may be a useful approach of disinfection for the preparation of natural cancellous bone with well-preserved structural, mechanical, and biological properties.

[Correlation of expression of silencing information regulator 2 related enzyme 1 and tumor necrosis factor-like weak inducer of apoptosis in articular effusion and knee osteoarthritis].

OBJECTIVE: To analyze the correlation between the expression of silencing information regulator 2 related enzyme 1 (SIRT1), tumor necrosis factor like weak inducer of apoptosis (TWEAK) and knee osteoarthritis. METHODS: Total of 103 patients with knee joint (knee osteoarthritis group) from February 2019 to August 2021 were selected including 40 males and 63 females with an average age of (62.02±6.09) years;according to the modified Mankin score, 103 patients were divided into mild group (Mankin score 1-4 points, 31 cases) and moderate group (Mankin score 5-8 points, 40 cases) and severe group (Mankin score ≥9, 32 cases). Another 105 physical examination volunteers were selected as the control group including 46 males and 59 females with an average age of (62.11±6.34) years old. The levels of SIRT1 and TWEAK in articular effusion and serum were detected in the knee osteoarthritis group, while serum SIRT1 and TWEAK were detected in the control group only. The relationship between SIRT1, TWEAK and the occurrence and disease of knee osteoarthritis were analyzed. RESULTS: Articular cavity fluid TWEAK, serum TWEAK, CRP, IL-6, IL-1ß, white blood cell count and ESR were higher than those in the control group(P<0.05), articular cavity fluid SIRT1 and serum SIRT1 were lower than those in the control group(P<0.05). TWEAK level in the severe group was higher than that in the moderate and mild groups(P<0.05), SIRT1 was lower than that in the moderate and mild groups (P<0.05). The level of SIRT1 in articular cavity effusion was positively correlated with the serum level of SIRT1 (P<0.05), and negatively correlated with CRP, IL-6, IL-1ß, white blood cell count, modified Mankin score and ESR (P<0.05). TWEAK level in articular cavity fluid was positively correlated with serum TWEAK level (P<0.05), C-reactive protein(CRP), interleukin(IL)-6, IL-1ß, white blood cell count, modified Mankin score and erythrocyte sedimentation rate(ESR) (P<0.05). Body mass index, undertaking heavy physical work, and articular cavity fluid TWEAK were risk factors for the occurrence of knee osteoarthritis(P<0.05), and articular cavity fluid SIRT1 was a protective factor for the occurrence of knee arthritis (P<0.05). The area under curve(AUC) of SIRT1 and TWEAK for knee osteoarthritis was 0.641 and 0.653, and the AUC of SIRT1 and TWEAK for knee osteoarthritis was 0.879, which was higher than SIRT1 and TWEAK alone (z=6.105 and 6.225, P<0.05). CONCLUSION: The level of SIRT1 in articular fluid in patients with knee arthritis is decreased and the level of TWEAK is increased. Low SIRT1 and high TWEAK are associated with the onset and exacerbation of knee osteoarthritis.

Microgroove Cues Guiding Fibrogenesis of Stem Cells via Intracellular Force.

Groove patterns are widely used in material surface modifications. However, the independent role of ditches/ridges in regulating fibrosis of soft tissues is not well-understood, especially the lack of linkage evidence in vitro and in vivo. Herein, two kinds of combinational microgroove chips with the gradient ditch/ridge width were fabricated by photolithography technology, termed R and G groups, respectively. In group R, the ridge width was 1, 5, 10, and 30 µm, with a ditch width of 30 µm; in group G, the groove width was 5, 10, 20, and 30 µm, and the ridge width was 5 µm. The effect of microgrooves on the morphology, proliferation, and expression of fibrous markers of stem cells was systematically investigated in vitro. Moreover, thicknesses of fibrous capsules were evaluated after chips were implanted into the muscular pouches of rats for 5 months. The results show that microgrooves have almost no effect on cell proliferation but significantly modulate the morphology of cells and focal adhesions (FAs) in vitro, as well as fibrosis differentiation. In particular, the differentiation of stem cells is attenuated after the intracellular force caused by stress fibers and FAs is interfered by drugs, such as rotenone and blebbistatin. Histological analysis shows that patterns of high intracellular force can apparently stimulate soft tissue fibrosis in vivo. This study not only reveals the specific rules and mechanisms of ditch/ridge regulating stem cell behaviors but also offers insight into tailoring implant surface patterns to induce controlled soft tissue fibrosis.

A combined chitosan/nano-size hydroxyapatite system for the controlled release of icariin.

Icariin, a plant-derived flavonol glycoside, has been proved as an osteoinductive agent for bone regeneration. For this reason, we developed an icariin-loaded chitosan/nano-sized hydroxyapatite (IC-CS/HA) system which controls the release kinetics of icariin to enhance bone repairing. First, by Fourier transform infrared spectroscopy, we found that icariin was stable in the system developed without undergoing any chemical changes. On the other hand, X-ray diffraction, scanning electron microscopy and mechanical test revealed that the introduction of icariin did not remarkably change the phase, morphology, porosity and mechanical strength of the CS/HA composite. Then the hydrolytic degradation and drug release kinetics in vitro were investigated by incubation in phosphate buffered saline solution. The results indicated that the icariin was released in a temporally controlled manner and the release kinetics could be governed by degradation of both chitosan and hydroxyapatite matrix. Finally the in vitro bioactivity assay revealed that the loaded icariin was biologically active as evidenced by stimulation of bone marrow derived stroma cell alkaline phosphatase activity and formation of mineralized nodules. This successful IC-CS/HA system offers a new delivery method of osteoinductive agents and a useful scaffold design for bone regeneration.

Sternal insufficiency fractures of post-menopausal women: retrospective analysis of 17 cases.

OBJECTIVE: To retrospectively investigate the clinical characteristics of sternal insufficiency fractures (SIFs) of post-menopausal women. METHODS: Findings on the clinical presentation, associated diseases, and imaging of SIFs in 17 postmenopausal women admitted to our hospital between February 1999 and January 2009 were reported. RESULTS: Twelve patients complained of severe pain in their anterior chest. Other symptoms included cough (5 cases), dyspnoea (3 cases), breathlessness (3 cases), and wheeze (2 cases). Four patients had no discomfort. The sternums of 11 cases were tender to palpation. Seventeen patients had osteoporosis. Other associated diseases were chronic obstructive pulmonary disease (7 cases), rheumatoid arthritis (3 cases), systemic lupus erythematosus (1 case), asthma (1 case), and thoracic vertebral fracture (13 cases). Nine patients had received glucocorticoid treatment. The fractures were located in the body of the sternum in 15 patients, in the manubrium in 1 patient, and in the manubriosternal junction in 1 patient. Displaced fracture was present in 13 cases. Lateral radiography of the sternum showed a fracture line in 14 patients. In the remaining 3 cases, other imaging examinations such as bone scan, computed tomography or magnetic resonance imaging demonstrated the presence of a fracture. CONCLUSIONS: Osteoporosis, glucocorticoid therapy, chronic obstructive pulmonary disease, and rheumatoid arthritis might be risk factors for SIFs. SIFs should be considered in the differential diagnosis of chest pain.

A 3D bioprinted nano-laponite hydrogel construct promotes osteogenesis by activating PI3K/AKT signaling pathway.

Development of nano-laponite as bioinks based on cell-loaded hydrogels has recently attracted significant attention for promoting bone defect repairs and regeneration. However, the underlying mechanisms of the positive function of laponite in hydrogel was not fully explored. In this study, the effect of 3D bioprinted nano-laponite hydrogel construct on bone regeneration and the potential mechanism was explored in vitro and in vivo. In vitro analyses showed that the 3D construct protected encapsulated cells from shear stresses during bioprinting, promoted cell growth and cell spreading, and BMSCs at a density of 107/mL exhibited an optimal osteogenesis potential. Osteogenic differentiation and ectopic bone formation of BMSCs encapsulated inside the 3D construct were explored by determination of calcium deposition and x-ray, micro-CT analysis, respectively. RNA sequencing revealed that activation of PI3K/AKT signaling pathway of BMSCs inside the laponite hydrogel significantly upregulated expression of osteogenic related proteins. Expression of osteogenic proteins was significantly downregulated when the PI3K/AKT pathway was inhibited. The 3D bioprinted nano-laponite hydrogel construct exhibited a superior ability for bone regeneration in rat bones with defects compared with groups without laponite as shown by micro-CT and histological examination, while the osteogenesis activity was weakened by applications of a PI3K inhibitor. In summary, the 3D bioprinted nano-laponite hydrogel construct promoted bone osteogenesis by promoting cell proliferation, differentiation through activation of the PI3K/AKT signaling pathway.

Effects of different cross-linking conditions on the properties of genipin-cross-linked chitosan/collagen scaffolds for cartilage tissue engineering.

A cross-linking reagent is required to improve mechanical strength and degradation properties of biopolymers for tissue engineering. To find the optimal preparative method, we prepared diverse genipin-cross-linked chitosan/collagen scaffolds using different genipin concentrations and various cross-linking temperatures and cross-linking times. The compressive strength increased with the increasing of genipin concentration from 0.1 to 1.0%, but when concentration exceeded 1.0%, the compressive strength decreased. Similarly, the compressive strength increased with the increasing of temperature from 4 to 20°C, but when temperature reached 37°C, the compressive strength decreased. Showing a different trend from the above two factors, the effect of cross-linking time on the compressive strength had a single increasing tendency. The other results also demonstrated that the pore size, degradation rate and swelling ratio changed significantly with different cross-linking conditions. Based on our study, 1.0% genipin concentration, 20°C cross-linking temperature and longer cross-linking time are recommended.

Mineral status and mechanical properties of cancellous bone exposed to hydrogen peroxide for various time periods.

Processed cancellous bone has been regarded as one alternative for the treatment of bone defects. In order to avoid immunogenic effects and preserve the natural properties of the bone, the optimal processing method should be determined. To observe the influence of hydrogen peroxide on the mineral status and mechanical properties of cancellous bone for various time periods and find the optimal processing time. Cancellous bone granules from bovine femur condyles were treated with 30% hydrogen dioxide for 0, 12, 24, 36, 48, 60 and 72 h separately. The microstructure and mineral content of the granules were evaluated by ash analysis, Micro-CT, scanning electron micrograph and energy dispersive X-ray. The biomechanical properties were analyzed by applying cranial-caudal compression in a materials testing machine. With increasing exposure to hydrogen peroxide, the BMD and BMC of granules gradually decreased, and the Ca/P molar ratios clearly increased (P < 0.05). Meanwhile, the mineral content of the granules increased from 48.5 ± 1.3 to 79.5 ± 2.1%. Substantial decreases in the strength of the granules were observed, and after 48 h severe decreases were noted. The decrease in strength was also evident after normalizing the parameters to the cross-sectional area. Granules of bovine cancellous bone matrix should be processed by hydrogen peroxide for 12 to 36 h to fulfill the basic requirements of a bone tissue engineering scaffold. These granules could potentially be useful during orthopedic operations.

The dose-effect of icariin on the proliferation and osteogenic differentiation of human bone mesenchymal stem cells.

Icariin had been reported as a potential agent for osteogenesis, but the dose-effect relationship needed further research to realize the clinical application of icariin. We isolated and purified human bone mesenchymal stem cells (hBMSCs) and stimulated them with different concentrations of icariin. The cytotoxicity of icariin was evaluated by the methylthiazolytetrazolium (MTT) assay method. The proliferation and osteogenic differentiation of such hBMSCs were investigated for different concentrations of icariin. We found that icariin had a dose-dependent effect on the proliferation and osteogenic differentiation of hBMSCs in a suitable concentration range from 10(-9) M to 10(-6) M, but at concentrations above 10(-5) M, the cytotoxicity limited its use. The extremely low cost of icariin and its high abundance make it appealing for bone regeneration.

Antibacterial and antibiofilm properties of graphene and its derivatives.

Infections resulting from bacteria and biofilms have become a huge problem threatening human health. In recent years, the antibacterial and antibiofilm effects of graphene and its derivatives have been extensively studied. However, there continues to be some controversy over whether graphene and its derivatives can resist infection and biofilms. Moreover, the antibacterial mechanism and cytotoxicity of graphene and its derivatives are unclear. In the present review, antibacterial and antibiofilm abilities of graphene and its derivatives in solution, on the surface are reviewed, and their toxicity and possible mechanisms are also reviewed. Furthermore, we propose possible future development directions for graphene and its derivatives in antibacterial and antibiofilm applications.

Coating CoCrMo Alloy with Graphene Oxide and ε-Poly-L-Lysine Enhances Its Antibacterial and Antibiofilm Properties.

INTRODUCTION: With increases in implant infections, the search for antibacterial and biofilm coatings has become a new interest for orthopaedists and dentists. In recent years, graphene oxide (GO) has been extensively studied for its superior antibacterial properties. However, most of these studies have focused on solutions and there are few antibacterial studies on metal surfaces, especially the surfaces of cobalt-chromium-molybdenum (CoCrMo) alloys. ε-Poly-L-lysine (ε-PLL), as a novel food preservative, has a spectrum of antimicrobial activity; however, its antimicrobial activity after coating an implant surface is not clear. METHODS: In this study, for the first time, a two-step electrodeposition method was used to coat GO and ε-PLL on the surface of a CoCrMo alloy. Its antibacterial and antibiofilm properties against S. aureus and E. coli were then studied. RESULTS: The results show that the formation of bacteria and biofilms on the coating surface was significantly inhibited, GO and ε-PLL composite coatings had the best antibacterial and antibiofilm effects, followed by ε-PLL and GO coatings. In terms of classification, the coatings are anti-adhesive and contact-killing/inhibitory surfaces. In addition to oxidative stress, physical damage to GO and electrostatic osmosis of ε-PLL are the main antibacterial and antibiofilm mechanisms. DISCUSSION: This is the first study that GO and ε-PLL coatings were successfully prepared on the surface of CoCrMo alloy by electrodeposition. It provides a promising new approach to the problem of implant infection in orthopedics and stomatology.