Recent advances in hydrogel-based anti-infective coatings

Bacterial infections associated with biomedical devices and implants have posed a great challenge to global healthcare systems.These infections are mainly caused by bacterial biofilm formed on the surface of biomaterials,protecting the encapsulated bacteria from conventional antibiotic treatment and attack of the immune system.As the bacterial biofilm is difficult to eradicate,bactericidal and antifouling coatings have emerged as promising strategies to prevent biofilm formation and subsequent infections.Hydrogels with three-dimensional crosslinked hydrophilic networks,tunable mechanical property and large drug-loading capacity are desirable coating materials,which can kill bacteria and/or prevent bacterial adhesion on the surface,inhibiting biofilm formation.Herein,we review recent developments of hydrogels as anti-infective coatings.Particularly,we highlight two chemical approaches(graft-from and graft-to),which have been used to immobilize hydrogels on surfaces,and present advances in the development of bactericidal(contact-killing and antimicrobial-releasing),antifouling(hydrophilic polymer network)and bifunctional hydrogel coatings with both bactericidal and antifouling activities.In addition,the challenges of hydrogel coatings for clinical applications are discussed,and future research directions of anti-infective hydrogel coatings are proposed.     

Rapid Biofilm Eradication on Bone Implants Using Red Phosphorus and Near‐Infrared Light

Bone‐implant‐associated infections are common after orthopedic surgery due to impaired host immune response around the implants. In particular, when a biofilm develops, the immune system and antibiotic treatment find it difficult to eradicate, which sometimes requires a second operation to replace the infected implants. Most strategies have been designed to prevent biofilms from forming on the surface of bone implants, but these strategies cannot eliminate the biofilm when it has been established in vivo. To address this issue, a nonsurgical, noninvasive treatment for biofilm infection must be developed. Herein, a red‐phosphorus–IR780–arginine–glycine–aspartic‐acid–cysteine coating on titanium bone implants is prepared. The red phosphorus has great biocompatibility and exhibits efficient photothermal ability. The temperature sensitivity of Staphylococcus aureus biofilm is enhanced in the presence of singlet oxygen (¹O₂) produced by IR780. Without damaging the normal tissue, the biofilm can be eradicated through a safe near‐infrared (808 nm) photothermal therapy at 50 °C in vitro and in vivo. This approach reaches an antibacterial efficiency of 96.2% in vivo with 10 min of irradiation at 50 °C. Meanwhile, arginine–glycine–aspartic‐acid–cysteine decorated on the surface of the implant can improve the cell adhesion, proliferation, and osteogenic differentiation.     

抗菌剂对聚乙烯表面生物被膜的抑制

采用共混方法在低密度聚乙烯中分别加入银系抗菌剂和Triclosan制备出两种改性聚乙烯,研究了材料的抗菌性能和抗菌剂对试样表面生物被膜的抑制作用.结果表明,两种改性聚乙烯对大肠杆菌和金黄色葡萄球菌都有良好的抗菌效果;细菌生物被膜的形成主要包括粘附、繁殖和成熟3个阶段,添加Triclosan的试样可以在生物被膜成熟前显著杀灭样品表面的细菌,阻止细菌在其表面粘附和繁殖,从而抑制生物被膜形成.空白试样和银系抗菌剂改性试样表面均有大量细菌粘附并形成生物被膜.     

Depriving Bacterial Adhesion‐Related Molecule to Inhibit Biofilm Formation Using CeO2‐Decorated Metal‐Organic Frameworks

The formation of bacterial biofilm is one of the causes of antimicrobial resistance, often leading to persistent infections and a high fatality rate. Therefore, there is an urgent need to develop novel and effective strategies to inhibit biofilm formation. Adenosine triphosphate (ATP) plays an important role in bacterial adhesion and biofilm formation through stimulating cell lysis and extracellular DNA (eDNA) release. Herein, a simple and robust strategy for inhibiting biofilm formation is developed using CeO₂‐decorated porphyrin‐based metal‐organic frameworks (MOFs). The function of extracellular ATP (eATP) can be inhibited by CeO₂ nanoparticles, leading to the disruption of the initial adhesion of bacteria. Furthermore, planktonic bacteria can be killed by cytotoxic reactive oxygen species (ROS) generated by MOFs. As a consequence, the synergic effect of eATP deprivation and ROS generation presents excellent capacity to prevent biofilm formation, which may provide a new direction for designing flexible and effective biofilm‐inhibiting systems.     

Surface modification of titanium substrates with silver nanoparticles embedded sulfhydrylated chitosan/gelatin polyelectrolyte multilayer films for antibacterial application

To develop Ti implants with potent antibacterial activity, a novel “sandwich-type” structure of sulfhydrylated chitosan (Chi-SH)/gelatin (Gel) polyelectrolyte multilayer films embedding silver (Ag) nanoparticles was coated onto titanium substrate using a spin-assisted layer-by-layer assembly technique. Ag ions would be enriched in the polyelectrolyte multilayer films via the specific interactions between Ag ions and –HS groups in Chi-HS, thus leading to the formation of Ag nanoparticles in situ by photo-catalytic reaction (ultraviolet irradiation). Contact angle measurement and field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscopy were employed to monitor the construction of Ag-containing multilayer on titanium surface, respectively. The functional multilayered films on titanium substrate [Ti/PEI/(Gel/Chi-SH/Ag) _n /Gel] could efficiently inhibit the growth and activity of Bacillus subtitles and Escherichia coli onto titanium surface. Moreover, studies in vitro confirmed that Ti substrates coating with functional multilayer films remained the biological functions of osteoblasts, which was reflected by cell morphology, cell viability and ALP activity measurements. This study provides a simple, versatile and generalized methodology to design functional titanium implants with good cyto-compatibility and antibacterial activity for potential clinical applications.     

In vitro evaluation of a multispecies oral biofilm over antibacterial coated titanium surfaces

Peri-implantitis is an infectious disease that affects the supporting soft and hard tissues around dental implants and its prevalence is increasing considerably. The development of antibacterial strategies, such as titanium antibacterial-coated surfaces, may be a promising strategy to prevent the onset and progression of peri-implantitis. The aim of this study was to quantify the biofilm adhesion and bacterial cell viability over titanium disc with or without antibacterial surface treatment. Five bacterial strains were used to develop a multispecies oral biofilm. The selected species represent initial (Streptococcus oralis and Actinomyces viscosus), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late (Porphyromonas gingivalis) colonizers. Bacteria were sequentially inoculated over seven different types of titanium surfaces, combining different roughness level and antibacterial coatings: silver nanoparticles and TESPSA silanization. Biofilm formation, cellular viability and bacterial quantification over each surface were analyzed using scanning electron microscopy, confocal microscopy and real time PCR. Biofilm formation over titanium surfaces with different bacterial morphologies could be observed. TESPSA was able to significantly reduce the cellular viability when compared to all the surfaces (p?<?0.05). Silver deposition on titanium surface did not show improved results in terms of biofilm adhesion and cellular viability when compared to its corresponding non-coated surface. The total amount of bacterial biofilm did not significantly differ between groups (p?>?0.05). TESPSA was able to reduce biofilm adhesion and cellular viability. However, silver deposition on titanium surface seemed not to confer these antibacterial properties.

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In vitro antimicrobial and biological properties of laser assisted tricalcium phosphate coating

Implant related infections are of great concern in modern surgery. In order to improve the implant performance and to reduce implant related infections, titanium (Ti) surface was modified to simultaneously improve cell-material interactions and antimicrobial activity. Ti surface was first coated with tricalcium phosphate (TCP) using Laser Engineered Net Shaping (LENS?) to improve biocompatibility. Silver (Ag) was then electrodeposited from different concentrations of silver nitrate (AgNO₃) solutions to improve the antimicrobial activity. The Ag-TCP coatings were tested for cytotoxicy with human osteoblast cells. The antimicrobial activities of the Ag-TCP coatings were evaluated using Pseudomonas aeruginosa and Staphylococcus aureus bacteria. In vitro bacterial adhesion study indicated a significant reduction in bacterial colony on Ag-TCP coated surfaces when compared to TCP coated surface.     

季铵盐接枝聚膦腈微球的制备及抗菌活性

细菌感染引起的疾病问题在世界范围内引起广泛的关注。抗生素虽然能有效治疗细菌感染,但是不合理的使用及滥用会导致细菌产生耐药性。因此,解决细菌耐药性问题并研发出安全高效的非抗生素抗菌剂显得尤为迫切。通过在生物可降解型环交联型聚(环三膦腈-共-聚乙烯亚胺)微球(PHP)表面上接枝环氧丙基十二烷基二甲基氯化铵(DDEAC),成功制备了环交联型聚(环三膦腈-共-聚乙烯亚胺)接枝季铵盐微球(PHPD)。采用FTIR、XPS、TG、TEM和FESEM对微球的结构与形貌进行了表征分析,并研究了其抗菌活性和细胞毒性。实验结果表明,改性抗菌微球PHPD(50 μg/mL)对大肠杆菌(E.coli)和金黄色葡萄球菌(S.aureus)的抗菌率均达97.3%。复合材料克服了单独使用季铵盐DDEAC材料的高毒性缺陷,并且在实现高效抗菌的同时也具有很好的细胞相容性。因此,本研究对于开发安全高效的纳米抗菌剂具有一定的指导意义。      

Microbial biofilm prevention on wound dressing by nanobiocoating using magnetosomes‐coupled lemon grass extract

In the present study, bacterial magnetosomes were used as a carrier molecule to couple with lemon grass extract (LGE) for the prevention of microbial biofilm in wound dressing material. Magnetosomes were extracted from Magnetospirillum sp. VITRJS‐1 and characterised by microscopic and X‐ray diffraction analysis. The phytochemical analyses of the extract showed the presence of bioactive compounds that are reported for antimicrobial and anti‐inflammatory activity. Gas chromatography–mass spectrometry analysis revealed the presence of antimicrobial citral and fernesal compounds. The extract was conjugated onto the magnetosomes and confirmed by Fourier transform infrared spectroscopy analysis. The prepared magnetosome–lemon grass extract (MLGE) was evaluated for its antibiofilm property against the biofilm‐forming pathogens Bacillus subtilis, Pseudomonas, Escherichia coli, Klebsiella and Staphylococcus aureus on wound dressing material by plate assay. The results indicated that the number of colonies formed was considerably reduced in MLGE coated wound dressing compared with that of LGE and control. Furthermore, SEM analysis displayed that the MLGE drastically reduced the spread of biofilm formation. Thus, MLGE coated wound dressings are effective in preventing the microbial biofilm formation, and further investigation on animal models will enable its use commercially.Inspec keywords: microorganisms, cellular biophysics, wounds, X‐ray diffraction, antibacterial activity, chromatography, mass spectra, Fourier transform infrared spectra, scanning electron microscopy, biochemistry, molecular biophysics, nanomedicineOther keywords: microbial biofilm, nanobiocoating, magnetosomes‐coupled lemon grass extract, extract bacterial magnetosomes, carrier molecule, wound dressing material, Magnetospirillum sp. VITRJS‐1, microscopic analysis, X‐ray diffraction, phytochemical analyses, bioactive compounds, antimicrobial activity, antiinflammatory activity, gas chromatography‐mass spectrometry, antimicrobial citral compounds, antimicrobial fernesal compounds, Fourier transform infrared spectroscopy, biofilm‐forming pathogens, Bacillus subtilis, Pseudomonas, Escherichia coli, Klebsiella, Staphylococcus aureus, SEM, MLGE coated wound dressings, microbial biofilm formation, animal models     

PolyNaSS grafting on titanium surfaces enhances osteoblast differentiation and inhibits <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> adhesion

Titanium surface modifications to simultaneously prevent bacterial adhesion but promote bone-cell functions could be highly beneficial for improving implant osseointegration. In the present in vitro study, the effect of sulfonate groups on titanium surfaces was investigated with respect to both S. aureus adhesion and osteoblast functions pertinent to new bone formation. Commercial pure titanium (cpTi) squares were oxydized (Tiox), grafted with poly(sodium styrene sulfonate) groups (Tigraft) by covalent bonding using radical polymerization, and were characterized by infrared spectroscopy (HATR-FTIR) and colorimetry. Bacterial adhesion study showed that Tigraft exhibited high inhibition of S. aureus adhesion S at levels >90 %, when compared to cpTi (P < 0.05). In contrast osteoblasts adhesion was similar on all three titanium surfaces. While the kinetics of cell proliferation were similar on the three titanium surfaces, Alkaline phosphatase-specific activity of osteoblasts cultured on Tigraft surfaces was twofold higher than that observed on either on Tiox or cpTi surfaces (P < 0.01). More importantly, the amount and the distribution of calcium-containing nodules was different. The total area covered by calcium-containing nodules was 2.2-fold higher on the Tigraft as compared to either Tiox or cpTi surfaces (P < 0.01). These results provide evidence that poly(sodium styrene sulfonate) groups grafting on cpTi simultaneously inhibits bacteria adhesion but promote osteoblast function pertinent to new bone formation. Such modified titanium surfaces offer a promising strategy for preventing biofilm-related infections and enhancing osteointegration of implants in orthopaedic and dental applications.     

Biofilm inhibition mechanism of BiVO4 inserted zinc matrix in marine isolated bacteria

Biofilm plays an important role on microbial corrosion and biofouling in marine environments.Inhibiting biofilm formation on construction surfaces is of great importance.Photocatalytic material with visible-light response,especially BiVO4,is regarded as a promising material for biofilm inhibition due to its green biocidal effect and high antibacterial efficiency.Approaches which can immobilize the photocatalytic par-ticles onto metal surfaces with high mechanical strength are requisite.In this study,zinc matrixes were served as carriers for BiVO4 particles.The BiVO4-inserted zinc matrixes were successfully obtained by ultrasound assisted electrodeposition.The insertion content of BiVO4 showed positive correlation with ultrasound power.Highly enhanced biofilm inhibition properties were obtained by BiVO4 inserted zinc matrixes with an over 95％decreased bacterial coverage.It was proved that·O2-(chief)and *OH(sub-ordinate)radicals were responsible for the high biocidal performance.Possible antibacterial mechanism was proposed,indicating that the photoinduced holes would both attack zinc crystals to generate active electrons to form·O2-radicals,and react with H2O to generate *OH,finally.Furthermore,corrosion resistance of the matrixes was proved to be stable due to the insertion of BiVO4.This study provides a potential application for photocatalyst in marine antifouling and anti-biocorrosion aspects.     

TiO<Subscript>2</Subscript>-containing and ZnO-containing borosilicate glass—a novel thin glass with exceptional antibiofilm performances to prevent microfouling

Biofilm formation, also known as microfouling, on indwelling medical devices such as catheters or prosthetic joints causes difficult to treat and recurrent infections. It is also the initial step for biocorrosion of surfaces in aquatic environment. An efficient prevention of microfouling is preferable but the development of antibiofilm surfaces is enormously challenging. Therefore, soda-lime, aluminosilicate, and three borosilicate glasses with different TiO₂ and ZnO compositions were investigated on their feasibility to prevent biofilm formation by standardized in vitro biofilm assays using different pathogenic bacteria. Furthermore, the biocompatibility of these glasses was evaluated using eukaryotic cell lines end erythrocytes. Only two borosilicate glasses, containing TiO₂ and ZnO, showed an increased antibiofilm performance inhibiting biofilm adhesion and formation. The biofilm thickness and area were significantly reduced by over 90?% and characterized by diffuse structures. All tested glass types showed neither cytotoxicity nor hemotoxicity. Therefore, the antibiofilm borosilicate-thin glasses are qualified for surface coatings where biofilms are not desirable such as on medical devices.     

Synthesis of chitosan/poly (ethylene glycol)-modified magnetic nanoparticles for antibiotic delivery and their enhanced anti-biofilm activity in the presence of magnetic field

Biocompatible Fe₃O₄/chitosan (CS)/poly (ethylene glycol) (PEG)/gentamicin (Gent) magnetic nanoparticles, namely Fe₃O₄@PEG-Gent NPs, have been successfully developed for antibiotic delivery. In which, PEG dicarboxylic acid was used to modify Fe₃O₄ NPs for good dispersity as well as offer sufficient carboxyl groups as binding sites. And then the free Gent was facilely loaded onto Fe₃O₄ NPs so as to achieve powerful antibacterial activity via electrostatic interactions. Under acidic condition, the CS and PEG of Fe₃O₄@PEG-Gent were protonated to introduce the positive charge to NPs surface, thus facilitating the contact with negatively charged bacterial cell membrane. What is more, the stretches of CS chains triggered by acidic pH may prevent the antimicrobial efficiency of Gent from weakening. Compared with the free antibiotic, these nanocomposites presented better antimicrobial efficacy against gram-positive bacteria S. aureus under acidic condition. Intriguingly, the confocal laser scanning macroscopy imaging suggested that the anti-biofilm efficacy of nanocomposites was significantly enhanced in the presence of an external magnetic field. Due to the superparamagnetic performance of Fe₃O₄ NPs, these nanocomposites were allowed deeper penetration into a mature biofilm of S. aureus by magnetic field, leading to an effective Gent delivery for eradication of biofilm. The ingenious fabrication of the antibiotic delivery system not only efficiently improved the effectiveness and bioavailability of Gent at acidic media, but also provided an innovative platform to treat bacterial biofilms-associated infection by applying extra environmental factors such as magnetic field.     

Antimicrobial and anti‐biofilm activities of Bi subnitrate and BiNPs produced by Delftia sp. SFG against clinical isolates of Staphylococcus aureus,Pseudomonas aeruginosa,and Proteus mirabilis

In the present study Delftia sp. Shakibaie, Forootanfar, and Ghazanfari (SFG), was applied for preparation of biogenic Bi nanoparticles (BiNPs) and antibacterial and anti‐biofilm activities of the purified BiNPs were investigated by microdilution and disc diffusion methods. Transmission electron micrographs showed that the produced nanostructures were spherical with a size range of 40–120 nm. The measured minimum inhibitory concentration of both the Bi subnitrate and BiNPs against three biofilms producing bacterial pathogens of Staphylococcus aureus, Pseudomonas aeruginosa, and Proteus mirabilis were found to be above 1280 µg/ml. Addition of BiNPs (1000 µg/disc) to antibiotic discs containing tobramycin, nalidixic acid, ceftriaxone, bacitracin, cefalexin, amoxicillin, and cefixime significantly increased the antibacterial effects against methicillin‐resistant S. aureus (MRSA) in comparison with Bi subnitrate (p  < 0.05). Furthermore, the biogenic BiNPs decreased the biofilm formation of S. aureus, P. aeruginosa, and P. mirabilis to 55, 85, and 15%, respectively. In comparison to Bi subnitrate, BiNPs indicated significant anti‐biofilm activity against P. aeruginosa (p  < 0.05) while the anti‐biofilm activity of BiNPs against S. aureus and P. mirabilis was similar to that of Bi subnitrate. To sum up, the attained results showed that combination of biogenic BiNPs with commonly used antibiotics relatively enhanced their antibacterial effects against MRSA.Inspec keywords: nanoparticles, bismuth, nanofabrication, antibacterial activity, microorganisms, biomedical materials, toxicology, nanomedicine, transmission electron microscopy, biochemistry, drugsOther keywords: Bi, size 40.0 nm to 120.0 nm, mass 1000.0 mug, Delftia sp. SFG, Staphylococcus aureus, antibiofilm mechanisms, antibiofilm effect, antibiofilm activity, Proteus mirabilis, Pseudomonas aeruginosa, purified biogenic BiNPs, antibacterial biofilm mechanisms, Bi subnitrate, antibacterial effects     

Superparamagnetic Iron Oxide Nanoparticles (SPION) for the Treatment of Antibiotic‐Resistant Biofilms

Bacterial infections caused by antibiotic‐resistant strains are of deep concern due to an increasing prevalence, and are a major cause of morbidity in the United States of America. In particular, medical device failures, and thus human lives, are greatly impacted by infections, where the treatments required are further complicated by the tendency of pathogenic bacteria, such as Staphylococcus aureus, to produce antibiotic resistant biofilms. In this study, a panel of relevant antibiotics used clinically including penicillin, oxacillin, gentamicin, streptomycin, and vancomycin are tested, and although antibiotics are effective against free‐floating planktonic S. aureus, either no change in biofilm function is observed, or, more frequently, biofilm function is enhanced. As an alternative, superparamagnetic iron oxide nanoparticles (SPION) are synthesized through a two‐step process with dimercaptosuccinic acid as a chelator, followed by the conjugation of metals including iron, zinc, and silver; thus, the antibacterial properties of the metals are coupled to the superparamagnetic properties of SPION. SPION might be the ideal antibacterial treatment, with a superior ability to decrease multiple bacterial functions, target infections in a magnetic field, and had activity better than antibiotics or metal salts alone, as is required for the treatment of medical device infections for which no treatment exists today.     

Polymer brushes as active nanolayers for tunable bacteria adhesion

Bacterial biofilm formation on implant surfaces is a frequent reason for the failure of many biomedical devices. Polymer brushes, thin nanolayers constituted of densely grafted macromolecules, are promising candidates to use in many biomedical applications to control attachment of bacteria to a surface. In this work five different polymer brushes were synthesized and tested with respect to their ability to regulate Staphylococcus aureus adhesion. Namely, two mixed brushes [consisting of poly(ethylene glycol) and a positively charged polymers, poly(2-vynil pyridine) or quartenized poly(2-vynil pyridine)] are investigated along with one-component brushes of the respective polymers. Bacterial adhesion was regulated over two orders of magnitude via altering the polymer brush composition.     

XPS study of the a-C:H/Ti and a-C:H/a-Si interfaces

In this study ultrathin hydrogenated amorphous carbon (a-C:H) films have been grown onto the titanium and amorphous silicon (a-Si) overlayers by direct ion beam deposition using acetylene gas as a hydrocarbon source. X-ray photoelectron spectroscopy (XPS) was used for study of the DLC-Ti and DLC-Si interfaces. It was revealed that a-Si is a good interlayer for improvement of adhesion in the case of diamond-like carbon film deposition onto the steel substrate at room temperature. a-C:H film growth without substantial intermixing occurred on the a-Si. On the other hand, adhesion between the Ti interlayer and the diamond like carbon film was very sensitive to the deposition conditions (presence of the pump oil) as well as structure and stress level of the Ti film. It was explained by strong intermixing between the growing carbon film and Ti. Bad adhesion between the growing DLC film and Ti interlayer was observed despite formation of the TiC. At the same time, formation of the TiO_x was not an obstacle for good adhesion. It is shown that composition of the used hydrocarbon gas, structure of the Ti thin film and mechanical stress in it had greater influence on adhesion with a-C:H film than elemental composition of the Ti interlayer surface.     

Antibacterial and anti-adhesion effects of the silver nanoparticles-loaded poly(l-lactide) fibrous membrane

The complications of tendon injury are frequently compromised by peritendinous adhesions and tendon sheath infection. Physical barriers for anti-adhesion may increase the incidence of postoperative infection. This study was designed to evaluate the potential of silver nanoparticles (AgNPs)-loaded poly(l-lactide) (PLLA) electrospun fibrous membranes to prevent adhesion formation and infection. Results of an in vitro drug release study showed that a burst release was followed by sustained release from electrospun fibrous membranes with a high initial silver content. Fewer fibroblasts adhered to and proliferated on the AgNP-loaded PLLA electrospun fibrous membranes compared with pure PLLA electrospun fibrous membrane. In the antibacterial test, the AgNP-loaded PLLA electrospun fibrous membranes can prevent the adhesion of Gram-positive Staphylococcus aureus and Staphylococcus epidermidis and Gram-negative Pseudomonas aeruginosa. Taken together, these results demonstrate that AgNP-loaded PLLA electrospun fibrous membranes have the convenient practical medical potential of reduction of infection and adhesion formation after tendon injury.     

Modification of titanium surfaces by adding antibiotic-loaded PHB spheres and PEG for biomedical applications

Novel researches are focused on the prevention and management of post-operative infections. To avoid this common complication of implant surgery, it is preferable to use new biomaterials with antibacterial properties. Therefore, the aim of this work is to develop a method of combining the antibacterial properties of antibiotic-loaded poly(3-hydroxybutyrate) (PHB) nano- and micro-spheres and poly(ethylene glycol) (PEG) as an antifouling agent, with titanium (Ti), as the base material for implants, in order to obtain surfaces with antibacterial activity. The Ti surfaces were linked to both PHB particles and PEG by a covalent bond. This attachment was carried out by firstly activating the surfaces with either Oxygen plasma or Sodium hydroxide. Further functionalization of the activated surfaces with different alkoxysilanes allows the reaction with PHB particles and PEG. The study confirms that the Ti surfaces achieved the antibacterial properties by combining the antibiotic-loaded PHB spheres, and PEG as an antifouling agent.     

Antibacterial surface design of biomedical titanium materials for orthopedic applications

Titanium(Ti)and titanium alloys have become widely used as biomedical materials in orthopedics because of their good machinability,corrosion resistance,low elastic modulus and excellent biocom-patibility.However,when Ti-based implants are used for bone repair and replacement,they are easy to cause bacteria adhesion and aggregation,which leads to postoperative infection.In addition,Ti and its alloys,as bio-inert materials,cannot induce desirable tissue responses such as osseointegration after implantation,which will eventually lead to implant loosening.Postoperative bacterial infection and lack of osseointegration directly lead to the failure of implantation surgery and are not conductive to the long-term service of titanium-based implants.Recently,researchers have made many attempts to focus on the surface modification of multifunctional Ti-based implants to endow them with both antibacterial activity and simultaneous osteoinductive property.In this review,we primarily highlighted the recent progresses in the surface design of Ti implants with both antimicrobial and osteoinductive properties for orthopedic applications.First,the challenges for treating implant-associated infections were briefly introduced such as the emergence of antibiotic resistance,the formation of biofilms,and the construction of cell-selective surfaces.Some of the essential fundamentals were concisely introduced to address these emerging challenges.Next,we intended to elaborate the potential strategies of multifunctional surface design to endow good osseointegration for antibacterial Ti implants and highlighted the recent advances of the implants.We hope that this review will provide theoretical basis and technical support for the development of new Ti implant with antibacterial and osteogenic functions.