Antibacterial activity and cytocompatibility of titanium oxide coating modified by iron ion implantation

Advancements in incorporating metal ions onto the surface of biomedical titanium and its alloys via micro-arc oxidation: a research review

The incorporation of biologically active metallic elements into nano/micron-scale coatings through micro-arc oxidation (MAO) shows significant potential in enhancing the biological characteristics and functionality of titanium-based materials. By introducing diverse metal ions onto titanium implant surfaces, not only can their antibacterial, anti-inflammatory and corrosion resistance properties be heightened, but it also promotes vascular growth and facilitates the formation of new bone tissue. This review provides a thorough examination of recent advancements in this field, covering the characteristics of commonly used metal ions and their associated preparation parameters. It also highlights the diverse applications of specific metal ions in enhancing osteogenesis, angiogenesis, antibacterial efficacy, anti-inflammatory and corrosion resistance properties of titanium implants. Furthermore, the review discusses challenges faced and future prospects in this promising area of research. In conclusion, the synergistic approach of micro-arc oxidation and metal ion doping demonstrates substantial promise in advancing the effectiveness of biomedical titanium and its alloys, promising improved outcomes in medical implant applications.

Advances in reparative materials for infectious bone defects and their applications in maxillofacial regions

Infectious bone defects are characterized by the partial loss or destruction of bone tissue resulting from bacterial contaminations subsequent to diseases or external injuries. Traditional bone transplantation and clinical methods are insufficient in meeting the treatment demands for such diseases. As a result, researchers have increasingly focused on the development of more sophisticated biomaterials for improved therapeutic outcomes in recent years. This review endeavors to investigate specific reparative materials utilized for the treatment of infectious bone defects, particularly those present in the maxillofacial region, with a focus on biomaterials capable of releasing therapeutic substances, functional contact biomaterials, and novel physical therapy materials. These biomaterials operate via heightened antibacterial or osteogenic properties in order to eliminate bacteria and/or stimulate bone cells regeneration in the defect, ultimately fostering the reconstitution of maxillofacial bone tissue. Based upon some successful applications of new concept materials in bone repair of other parts, we also explore their future prospects and potential uses in maxillofacial bone repair later in this review. We highlight that the exploration of advanced biomaterials holds promise in establishing a solid foundation for the development of more biocompatible, effective, and personalized treatments for reconstructing infectious maxillofacial defects.

Ilmenite-derived titanic acid species: exploring their outstanding light-independent antibacterial activity

The emergence of resistance in detrimental pathogenic bacteria towards well-recognized antibiotics has greatly impacted global medicine, consequently exploring potent antibacterial compounds is becoming a potential area of research. Although photocatalytic metal oxides have been extensively explored in this regard, their applicability is diminished due to the requirement of photon energy. Therefore, in our study, we explored the light-independent antibacterial effect of two unexplored titanium species, known as metatitanic acid (MTA) and potassium titanate, against Staphylococcus aureus, Escherichia coli, and Pseudomonas spp. using the disk diffusion method in Luria-Bertani agar medium, where the well-known antibiotic, gentamicin, was used as the positive control. These two titanium compounds were readily synthesized through a novel process which was originally developed for the extraction of TiO2 from ilmenite. The synthesized MTA was characterized using FT-IR, Raman spectroscopy, XRD, TGA, UV-visible spectroscopy, and SEM. According to our findings, both MTA and potassium titanate exhibited superior light-independent antibacterial properties, where for some concentrations, the effect was even greater than gentamicin. However, nano-TiO2 totally failed as an antibacterial compound against the tested three strains under dark conditions.

Study on TiO2 Nanofilm That Reduces the Heat Production of Titanium Alloy Implant in Microwave Irradiation and Does Not Affect Fracture Healing

Background

Metal implants can produce heat and damage adjacent tissues under microwave irradiation, which makes local metal implants in the body a contraindication for microwave therapy. However, with the wide application of titanium alloy implants which have low permeability and low conductivity, this concept has been challenged. Our team members have confirmed through previous research that continuous low-power microwave irradiation does not cause thermal damage to the surrounding tissues of the titanium alloy. Is there any other way to further increase the dose of microwave irradiation while reducing the heat production of titanium alloy implants? In this study, the effect of TiO₂ nanofilm on reducing the heat production of titanium alloy implants in microwave field was verified by animal experiments, and the effect of TiO₂ nanofilm on fracture healing was observed.

Methods

30 rabbits were selected. In the experiment of temperature measurement, 10 rabbits were randomly divided into experimental group (n = 5) and control group (n = 5), and the contralateral lower limb of the rabbits in experimental group was set as the sham operation group. The right femurs in the experimental group were implanted with Ti6Al4V plates coated with TiO₂ nanofilm, and the right femurs in the control group were implanted with common titanium alloy plates without TiO₂ nanofilm. The same surgical procedure was used in the sham operation group, but no plate was implanted. The temperature of the deep tissue above the metal implant was measured with an anti-interference thermocouple thermometer during 20 minutes of microwave irradiation. The other 20 rabbits were randomly divided into two groups, experimental group (n = 10) and control group (n = 10). The femoral shaft fracture models were established again. Ti6Al4V plates coated with TiO₂ nanofilm and common titanium alloy plates were implanted in the two groups, respectively, and both groups were exposed to continuous microwave irradiation with a power of 40 W or 60 W for 30 days after operation. The fracture healing was evaluated by X-ray at 0 day, 14 days, and 30 days after microwave irradiation, respectively. The animals were sacrificed at 30 days after operation for histopathological assessment.

Results

The temperature in the experimental group, control group, and sham operation group increased significantly after 40 W and 60 W microwave irradiation (2.18 ± 0.15°C~6.02 ± 0.38°C). When exposed to 40 W microwave, the temperature rise of the control group was 4.0 ± 0.34°C, which was significantly higher than that of the experimental group 2.82 ± 0.15°C (P < 0.01) and the sham operation group 2.18 ± 0.33°C (P < 0.01). There was no significant difference in temperature rise between the experimental group and the sham operation group (P = 0.21). When exposed to 60 W microwave, the temperature rise of the control group was 6.02 ± 0.38°C, which was significantly higher than that of the experimental group 3.66 ± 0.14°C (P < 0.01) and sham operation group 2.96 ± 0.22°C (P < 0.01), and there was no significant difference between the experimental group and the sham operation group (P = 0.32). X-ray evaluation showed that there was no significant difference in callus maturity between the experimental group and the control group at 14 days (P = 0.554), but there was significant difference in callus maturity between the two groups at 30 days (P = 0.041). The analysis of bone histologic and histomorphometric data at 30 days was also consistent with this.

Conclusion

Under the animal experimental condition, compared with the common titanium alloy implant, the TiO₂ nanofilm can reduce the heat production of the titanium alloy implant in the 2450 MHz microwave field and has no adverse effect on fracture healing. This study opens up a promising new idea for the application of microwave therapy to metal implants in human body.

Ultrafast gelation of multifunctional hydrogel/composite based on self-catalytic Fe3+/Tannic acid-cellulose nanofibers

Multifunctional hydrogels with transparency, ultraviolet (UV)-blocking, stretchable, self-healing, adhesive, antioxidant and antibacterial properties are promising materials for biomedical and relevant applications. However, preparation of these hydrogels at ambient environment without stimuli is still a challenge. Here, a series of hydrogels possessing ultrashort gelation time (~30 s) at room or cold temperature were fabricated based on self-catalytic Fe³⁺/Tannic acid-cellulose nanofiber (Fe³⁺/TA-CNF). Fe³⁺/TA-CNF formed stable redox pairs to activate ammonium persulfate (initiator), generating abundant free radicals to trigger the ultrafast polymerization of acrylic acid (AA). To improve the antibacterial ability of hydrogel, a bilayer hydrogel composite (NF@HG) composed of tetracycline hydrochloride (TH)-loaded electrospun nanofibers and hydrogel layer was fabricated via a mild casting method. The NF@HG exhibited enhanced antibacterial ability and the sustained release of TH can provide long-term antibacterial activity. Besides, cell viability results demonstrated that NF@HG was non-cytotoxic. Taken together, this strategy based on self-catalytic Fe³⁺/TA-CNF system may inspire new aspects on fast and economical preparation of multifunctional hydrogels or composites, which have attractive industrial applications for biomedical materials.

Biomedical Implants with Charge-Transfer Monitoring and Regulating Abilities

Transmembrane charge (ion/electron) transfer is essential for maintaining cellular homeostasis and is involved in many biological processes, from protein synthesis to embryonic development in organisms. Designing implant devices that can detect or regulate cellular transmembrane charge transfer is expected to sense and modulate the behaviors of host cells and tissues. Thus, charge transfer can be regarded as a bridge connecting living systems and human-made implantable devices. This review describes the mode and mechanism of charge transfer between organisms and nonliving materials, and summarizes the strategies to endow implants with charge-transfer regulating or monitoring abilities. Furthermore, three major charge-transfer controlling systems, including wired, self-activated, and stimuli-responsive biomedical implants, as well as the design principles and pivotal materials are systematically elaborated. The clinical challenges and the prospects for future development of these implant devices are also discussed.

Application of Nanotechnology in Immunity against Infection

The immune system has a physiological defense function, protecting the body from infectious diseases. Antibiotics have long been one of the most important means to treat infectious diseases, but in recent years, with the emergence of more and more multidrug-resistant (MDR) bacteria, it has become urgent to find new ways or drugs to treat infectious diseases. Nanoparticles (NPs) have attracted extensive attention owing to the special properties within the particle size range of 1–100 nanometers. In addition, NPs also have special shape symmetry and relative structural stability. The emergence of nanotechnology has brought new light to the widespread existence of MDR by its different antibacterial mechanisms. In addition to antibiotic nanocarriers being able to improve the antibacterial effect of antibiotics, some NPs also have certain antibacterial effect. What is more interesting is that linking functional groups on the surface of NPS as coatings can improve the stability of the whole system and improve the biocompatibility. The present review overviews the development of antimicrobial agents, so as to better understand the causes and mechanisms of antibiotic resistance in most microbial species, and to better think and explore new strategies to solve the problem. At the same time, this review introduces how nanotechnology can be applied to anti-infection immunity and its practical application and advantages in the treatment of infection.

Impact of exogenous metal ions on peri-implant bone metabolism: a review

The development of effective methods to promote the osseointegration of dental implants by surface modification is an area of intense research in dental materials science. Exogenous metal ions present in the implant and surface modifications are closely related to the bone metabolism around the implant. In the complex oral microenvironment, the release of metal ions caused by continuous corrosion of dental implants has an unfavorable impact on the surrounding tissue, and then affects osseointegration, leading to bad results such as loosening and falling off in the late stage of the implant. Besides, these ions can even be distributed in distant tissues and organs. Currently, surface modification techniques are being developed that involve different processing technologies including the introduction of exogenous metal ions with different properties onto the surface of implants to improve performance. However, most metal elements have some level of biological toxicity and can only be used within a safe concentration range to exert the optimum biological effects on recipients. In this paper, we review the adverse effects of metal ions on osseointegration and highlight the emerging applications for metal elements in improving the performance of dental implants.

A facile and universal strategy to endow implant materials with antibacterial ability via alkalinity disturbing bacterial respiration

Multifarious strategies have been proposed to enhance the antibacterial ability of implant surfaces for preventing bacterial infection, however, developing facile and universal modification methods still remains extremely elusive. Herein, inspired by the fact that the electron transfer respiratory chain of bacteria is embedded in the membrane, we proposed a novel strategy of local alkalinity disturbing bacterial respiration to endow implant materials with antibacterial ability. As a demonstration, MgO was deposited on biomedical titanium via magnetron sputtering to regulate surface alkalinity. With the thickness of MgO films increasing, they exhibited an excellent antibacterial rate against both Gram-negative and positive bacteria. The antibacterial mechanism confirmed that the alkaline surface can disturb the bacterial respiration action via weakening the transmembrane proton concentration gradient, resulting in the blockage of energy metabolism and the increase of oxidative stress of bacteria. Cell experiments indicated that MgO films not only have no obvious cytotoxicity to osteoblast cells, but can also selectively kill bacteria and promote cell proliferation in the presence of both bacteria and cells. More importantly, the by-product of MgO was only the biocompatible Mg2+, reducing any concerns about potential toxic effects. Furthermore, sputtering alkaline MgO films was confirmed to work well on polyetheretherketone polymer and zirconia ceramic implants, which indicates that this strategy has broad prospects of clinical application for preventing implant-associated bacterial infection.

Effects of carbon and nitrogen plasma immersion ion implantation on bioactivity of zirconia

Zirconia is considered the most promising alternative material to titanium implants. However, zirconia is a biologically inert material and its surface modification is essential to obtain efficient osseointegration. Plasma immersion ion implantation (PIII) is a controllable and flexible approach that constructs functional groups on the surface of biomaterials and enhances osteogenic ability of host osteoclast cells. Zirconia disks were randomly divided into 4 groups (n = 50/group): (1) Blank, (2) C60N0, (3) C60N6, and (4) C60N18. Carbon and nitrogen plasma immersion ion implantation on zirconia (C and N₂-PIII) surface modification was completed with the corresponding parameters. When zirconia was modified by carbon and nitrogen plasma implantation, a new chemical structure was formed on the material surface while the surface roughness of the material remained unaltered. The nitrogen-containing functional groups with high potential were introduced but the bulk crystal structure of zirconia was not changed, indicating that the stability of zirconia was not affected. In vitro data showed that zirconia with high surface potential promoted adhesion, proliferation, and osteogenic differentiation of BMSCs. C60N6 was found to be superior to the other groups. Our results demonstrate that a zirconia surface modified by C and N₂-PIII can introduce desirable nitrogen functional groups and create a suitable extracellular environment to promote BMSCs biological activity. Taken together, these results suggest that C and N₂-PIII modified zirconia is a promising material for use in the field of medical implantation.

Zirconia is considered the most promising alternative material to titanium implants.

Intrafibrillar Mineralized Collagen-Hydroxyapatite-Based Scaffolds for Bone Regeneration

As one of the major challenges in the field of tissue engineering, large skeletal defects have attracted wide attention from researchers. Collagen (Col) and hydroxyapatite (HA), the most abundant protein and the main component in natural bone, respectively, are usually used as a biomimetic composite material in tissue engineering due to their excellent biocompatibility and biodegradability. In this study, novel intrafibrillar mineralized Col-HA-based scaffolds, constructed in either cellular or lamellar microstructures, were established through a biomimetic method to enhance the new bone-regenerating capability of tissue engineering scaffolds. Moreover, iron (Fe) and manganese (Mn), two of the essential trace elements in the body, were successfully incorporated into the lamellar scaffold to further improve the osteoinductivity of these biomaterials. It was found that the lamellar scaffolds demonstrated better osteogenic abilities compared to both in-house and commercial Col-HA-based cellular scaffolds in vitro and in vivo. Meanwhile, Fe/Mn incorporation further amplified the osteogenic promotion of the lamellar scaffolds. More importantly, a synergistic effect was observed in the Fe and Mn dual-element-incorporated lamellar scaffolds for both in vitro osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and in vivo bone regeneration loaded with fresh bone marrow cells. This study provides a simple but practical strategy for the creation of functional scaffolds for bone regeneration.

Multifunctional sulfonated polyetheretherketone coating with beta-defensin-14 for yielding durable and broad-spectrum antibacterial activity and osseointegration

To address periprosthetic joint infection (PJI), a formidable complication after joint arthroplasty, an implant with excellent osseointegration and effective antibacterial activity has being extensively pursued and developed. In this work, the mouse beta-defensin-14 (MBD-14) was immobilized on the polyetheretherketone (PEEK) surface with three-dimensional (3D) porous structure to improve its antibacterial activity and osseointegration. An in vitro antibacterial evaluation showed that the porous PEEK loaded with MBD-14 wages a durable and effective fight against both Staphylococcus aureus (gram-positive) and Pseudomonas aeruginosa (gram-negative). In addition to the superior antibacterial activity, we found that the enhanced proliferation and osteogenic differentiation of bone mesenchymal stem cells were verified through various in vitro analyses. To evaluate the in vivo bactericidal effect and osseointegration of the samples, the rat femoral models with infection and non-infection were established. The enhanced osseointegration of the MBD-14-loaded samples was found in both two in vivo models. And no bacteria survived on the surfaces of samples with a relatively high MBD-14 concentration. Above results indicate that the 3D porous PEEK coating loaded with MBD-14 simultaneously yields excellent osseointegration while exerting durable and broad-spectrum antibacterial activity. And it paves the way for PEEK to be applied clinically to address PJI. STATEMENT OF SIGNIFICANCE: (1). By using the physio-chemical technique including sulfonation and lyophilization etc., a three-dimensional porous network is developed on polyetheretherketone (PEEK) surface, in which mouse beta-defensin-14 (MBD-14, a broad-spectrum antimicrobial peptide) is then loaded. It endows PEEK with antibacterial activity and osseointegration. (2). Two in vivo animal models with infection and non-infection are used to prove the new bone formation around the samples. (3). Supplementary material also proves that MBD-14 promotes the osteogenic differentiation of BMSCs. However, its potential mechanism needs to be further studied in future. (4). The modified PEEK, including excellent osseointegration and a durable and broad-spectrum antibacterial activity, could be applied clinically to address PJI which is a hot potato for surgeons and patients undergoing total joint arthroplasty.

Effect of Local Alkaline Microenvironment on the Behaviors of Bacteria and Osteogenic Cells

The interactions between material surfaces and bacteria/cells have been widely investigated, based on which biomaterials with antibacterial and osteogenic abilities can be designed to conquer implant failures. The pH of environments is known to affect bacterial growth and bone formation/resorption, and it is possible that the antibacterial and osteogenic abilities of biomaterials can be simultaneously improved by regulating their surface alkalinity. Herein, we fabricated many kinds of films with various alkalinity levels on titanium surface to explore the effect of local alkaline microenvironments around material surfaces on the behaviors of bacteria and osteogenic cells. Both Gram-positive and -negative bacteria were cultured on sample surfaces to investigate their antibacterial effects. Cell adhesion, proliferation, and alkaline phosphatase (ALP) activities were investigated by culturing both bone mesenchymal stem cells (MSCs) and osteoblast cells on sample surfaces. The results show that an appropriate local alkaline environment can effectively inhibit the growth of both Gram-positive and -negative bacteria through inactivating ATP synthesis and inducing oxidative stress. Meanwhile, it can promote the osteogenic differentiation of bone MSCs and enhance the proliferation and ALP activities of osteoblast cells. In conclusion, material surfaces endowed with appropriate alkalinity can possess antibacterial and osteogenic properties, which provide a novel strategy to design multifunctional biomaterials for bone generation.

Investigation of osteogenic responses of Fe-incorporated micro/nano-hierarchical structures on titanium surfaces

Fe incorporated micro/nano topographical titanium substrates are fabricated to synergistically regulate osteogenic responses in vitro and osseointegration in vivo.

Chitosan coating as an antibacterial surface for biomedical applications

Background and objectives

A current public health issue is preventing post-surgical complications by designing antibacterial implants. To achieve this goal, in this study we evaluated the antibacterial activity of an animal-free chitosan grafted onto a titanium alloy.

Methods

Animal-free chitosan binding on the substrate was performed by covalent link via a two-step process using TriEthoxySilylPropyl Succinic Anhydride (TESPSA) as the coupling agent. All grafting steps were studied and validated by means of X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight secondary ion mass spectrometry (ToF-SIMS) analyses and Dynamic-mode Secondary Ion Mass Spectrometry (DSIMS). The antibacterial activity against Escherichia coli and Staphylococcus aureus strains of the developed coating was assessed using the number of colony forming units (CFU).

Results

XPS showed a significant increase in the C and N atomic percentages assigned to the presence of chitosan. A thick layer of polymer deposit was detected by ToF-SIMS and the results obtained by DSIMS measurements are in agreement with ToF-SIMS and XPS analyses and confirms that the coating synthesis was a success. The developed coating was active against both gram negative and gram positive tested bacteria.

Conclusion

The success of the chitosan immobilization was proven using the surface characterization techniques applied in this study. The coating was found to be effective against Escherichia coli and Staphylococcus aureus strains.

Mn-containing titanium surface with favorable osteogenic and antimicrobial functions synthesized by PIII&D

Reasonable incorporation of manganese into titanium is believed to be able to enhance the osteogenic and antibacterial activities of orthopedic implants. However, it is still a challenge to compromise Mn-induced cytotoxicity and better develop its biocompatibility and antimicrobial ability. To pinpoint this issue, a stable Mn ion release platform was created on Ti using plasma immersion ion implantation and deposition (PIII&D) technique. Compared with as-etched titanium, as a result, promoted antibacterial abilities against gram-negative bacteria species and enhanced osteogenic-related gene expressions on rBMMSC were observed on Mn-containing sample. Meanwhile, the Mn-containing samples showed no obvious cytotoxicity. Our results here provide insight to be better understanding the relationships between additives-induced biological performance and the dose, state, and stability of the doped element.

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.

Study on a hydrophobic Ti-doped hydroxyapatite coating for corrosion protection of a titanium based alloy

In the paper, hydroxyapatite coatings enriched with Ti were prepared as a possible candidate for biomedical applications, especially for implantable devices that are in direct contact with bone.

Synthesis of Ag ion-implanted TiO2 thin films for antibacterial application and photocatalytic performance

TiO2 thin films were deposited by spin coating method. Silver ions were implanted into the films using a Metal Vapor Vacuum Arc implanter. The antibacterial ability of implanted films was tested using Escherichia coli removal under fluorescent irradiation and in the dark. The concentration of E. coli was evaluated by plating technique. The photocatalytic efficiency of the implanted films was studied by degradation of methyl orange under fluorescent illumination. The surface free energy of the implanted TiO2 films was calculated by contact angle testing. Vitamin C was used as radical scavengers to explore the antibacterial mechanism of the films. The results supported the model that both generation of reactive oxygen species and release of silver ions played critical roles in the toxic effect of implanted films against E. coli. XPS experimental results demonstrated that a portion of the Ag(Ag(3+)) ions were doped into the crystalline lattice of TiO2. As demonstrated by density functional theory calculations, the impurity energy level of subtitutional Ag was responsible for enhanced absorption of visible light. Ag ion-implanted TiO2 films with excellent antibacterial efficiency against bacteria and decomposed ability against organic pollutants could be potent bactericidal surface in moist environment.

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.

Nanostructured Architectures by Assembling Polysaccharide-Coated BSA Nanoparticles for Biomedical Application

Nanostructured architectures are produced on Ti surfaces by layer-by layer (LbL) self-assembling of polysaccharide-coated BSA nanoparticles (BNPs), which created cellular microenvironments mimicking natural extracellular matrix. The BMP-2 encapsulated BNPs are prepared by a desolvation method, and are further coated by chitosan (CHI) coatings to obtain positively charged NPs (CBNPs). Vancomycin (Van) encapsulated CBNPs are obtained by the same method and subsequently coated by oxidized alginate (OALG) to obtain negatively charged NPs (OCBNPs). The CBNPs and OCBNPs are assembled on Ti surfaces to construct nanostructured coatings via electrostatic and covalent interactions. The nanostructured architectures realize the sustained release of BMP-2 and Van for a long term. Bone marrow stromal cells (BMSCs) culture tests confirm that the bare nanostructured architectures intrinsically facilitate attachment, proliferation, and differentiation of cells, which is attributed to the nanoscale porous structures that are similar to the size of cellular filopodia. Incorporating BMP-2 into the nanostructured architectures significantly enhances osteogenetic differentiation of BMSCs, which reveals the synergistic effects of nanostructures and growth factors on cell activity. The antibacterial tests indicate that controlled release of Van has good antibacterial ability against Staphylococcus epidermidis, while not affecting the normal biological activity of BMSCs.

Reduction of bacterial adhesion on dental composite resins by silicon-oxygen thin film coatings

Adhesion of bacteria on dental materials can be reduced by modifying the physical and chemical characteristics of their surfaces, either through the application of specific surface treatments or by the deposition of thin film coatings. Since this approach does not rely on the use of drugs or antimicrobial agents embedded in the materials, its duration is not limited by their possible depletion. Moreover it avoids the risks related to possible cytotoxic effects elicited by antibacterial substances released from the surface and diffused in the surrounding tissues. In this work, the adhesion of Streptococcus mutans and Streptococcus mitis was studied on four composite resins, commonly used for manufacturing dental prostheses. The surfaces of dental materials were modified through the deposition of a-SiO(x) thin films by plasma enhanced chemical vapor deposition. The chemical bonding structure of the coatings was analyzed by Fourier-transform infrared spectroscopy. The morphology of the dental materials before and after the coating deposition was assessed by means of optical microscopy and high-resolution mechanical profilometry, while their wettability was investigated by contact angle measurements. The sample roughness was not altered after coating deposition, while a noticeable increase of wettability was detected for all the samples. Also, the adhesion of S. mitis decreased in a statistically significant way on the coated samples, when compared to the uncoated ones, which did not occur for S. mutans. Within the limitations of this study, a-SiO(x) coatings may affect the adhesion of bacteria such as S. mitis, possibly by changing the wettability of the composite resins investigated.

Tethering silver ions on amino-functionalized mesoporous silica for enhanced and sustained antibacterial properties

Amino group-based tethering method is an effective strategy to load Ag ions for long-term and highly efficient antibacterial activity. The developed Ag–CaMSS is a promising surgical implantation material with excellent antibacterial activity.