Mussel-inspired self-assembly engineered implant coatings for synergistic anti-infection and osteogenesis acceleration

Exploring Naturally Tailored Bacterial Outer Membrane Vesicles for Selective Bacteriostatic Implant Coatings

In treating infectious diseases, achieving selective bacterial inhibition is crucial for preserving the microecological equilibrium. The current approaches predominantly rely on synthetic materials tailored to specific bacteria, considering their cell walls or oxygen requirements. Herein, inspired by intricate bacterial communication, a natural implant is proposed coating utilizing bacterial outer membrane vesicles (OMVs), essential components in bacterial signaling, integrated onto diverse implant surfaces through a universal poly (tannic acid) bridging layer. This coating is homogenous and stable, unexpectedly promoting the proliferation of parental bacteria while inhibiting heterologous bacteria both in vitro and in vivo. Through high-throughput sequencing and bioinformatics analysis, the selective bacteriostatic ability arises from OMVs, upregulating anti-oxidative stress genes in heterologous bacteria and activating biofilm-related genes in parental bacteria. This study positions OMVs as an appealing biomaterial for selective bacterial inhibition through a biological approach, showcasing their potential in regulating the microecological balance through a natural interface modification strategy.

Enhancing antibacterial properties of titanium implants through a novel Ag-TiO2-OTS nanocomposite coating: a comprehensive study on resist-killing-disintegrate approach

Titanium (Ti) implants are widely used in orthopedic and dental applications due to their excellent biocompatibility and mechanical properties. However, bacterial adhesion and subsequent biofilm formation on implant surfaces pose a significant risk of postoperative infections and complications. Conventional surface modifications often lack long-lasting antibacterial efficacy, necessitating the development of novel coatings with enhanced antimicrobial properties. This study aims to develop a novel Ag-TiO2-OTS (Silver-Titanium dioxide-Octadecyltrichlorosilane, ATO) nanocomposite coating, through a chemical plating method. By employing a 'resist-killing-disintegrate' approach, the coating is designed to inhibit bacterial adhesion effectively, and facilitate pollutant removal with lasting effects. Characterization of the coatings was performed using spectroscopy, electron microscopy, and contact angle analysis. Antibacterial efficacy, quantitatively evaluated against E. coli and S. aureus over 168 h, showed a significant reduction in bacterial adhesion by 76.6% and 66.5% respectively, and bacterial removal rates were up to 83.8% and 73.3% in comparison to uncoated Ti-base material. Additionally, antibacterial assays indicated that the ratio of the Lifshitz-van der Waals apolar component to electron donor surface energy components significantly influences bacterial adhesion and removal, underscoring a tunable parameter for optimizing antibacterial surfaces. Biocompatibility assessments with the L929 cell line revealed that the ATO coatings exhibited excellent biocompatibility, with minimal cytotoxicity and no significant impact on cell proliferation or apoptosis. The ATO coatings provided a multi-functionality surface that not only resists bacterial colonization but also possesses self-cleaning capabilities, thereby marking a substantial advancement in the development of antibacterial coatings for medical implants.

Thermal control of photothermal implants inspired by polar bear skin for the treatment of infected bone defects

Photothermal therapy (PTT) encounters challenges in addressing deep tissue infections, characterized by limited penetration or potential hyperthermal damage to surrounding tissues, initiating undesirable inflammatory cascades. Inspired by polar bear thermal regulation, we present a "bio-based endogenic thermal-adaptive booster" implant coating. This coating integrates a photothermal poly(tannic acid) (pTA) layer, mimicking the "polar bear dark skin", securely linked with anti-inflammatory dexamethasone (Dex), resembling the "secretion", and a red blood cell membrane (RBCM) layer, forming the insulating "transparent fur". The RBCM "fur" demonstrates unexpectedly superior local heat storage, amplifying the photothermal effect of the pTA "skin" by 1.30 times and boosting localized photothermal antibacterial efficiency by 1.30-fold (approximately 99%) compared to those without RBCM. Furthermore, RBCM sustains Dex release and offers additional protection against thermal inflammation, releasing Dex 1.90 times more under NIR irradiation than under non-photothermal conditions. In a rat infectious bone model, the photothermal-boosting implant coating provides a favorable biological interface and achieves a 99.97% photothermal antibacterial ratio, enhancing osseointegration without evident tissue harm, evidenced by a 2.47-fold increase in bone volume fraction and a 2.24-fold reduction in pro-inflammatory cytokines compared to those lacking a RBCM. Insights derived from cell membrane-based thermal-adaptive coatings herald a paradigm shift in efficient and safe PTT.

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.

Oxidative Coupling and Self-Assembly of Polyphenols for the Development of Novel Biomaterials

In recent years, the development of biomaterials from green organic sources with nontoxicity and hyposensitivity has been explored for a wide array of biotherapeutic applications. Polyphenolic compounds have unique structural features, and self-assembly by oxidative coupling allows molecular species to rearrange into complex biomaterial that can be used for multiple applications. Self-assembled polyphenolic structures, such as hollow spheres, can be designed to respond to various chemical and physical stimuli that can release therapeutic drugs smartly. The self-assembled metallic-phenol network (MPN) has been used for modulating interfacial properties and designing biomaterials, and there are several advantages and challenges associated with such biomaterials. This review comprehensively summarizes current challenges and prospects of self-assembled polyphenolic hollow spheres and MPN coatings and self-assembly for biomedical applications.

Fabrication of graphene oxide/copper synergistic antibacterial coating for medical titanium substrate

Titanium (Ti) was an excellent medical metal material, but the lack of good antibacterial activity confined its further practical application. To solve this dilemma, a coating containing graphene oxide (GO) and copper (Cu) was prepared on the surface of Ti sheet (Ti/APS/GO/Cu). First, physical sterilization could be carried out through the sharp-edged sheet structure of GO. Second, the oxygen-containing functional group on the surface of GO and the released Cu²⁺ would generate reactive oxygen species for chemical sterilization. The synergistic effect of GO and Cu substantially enhanced the in vitro and in vivo antibacterial property of Ti sheet, thereby reducing bacterial-related inflammation. Quantitatively, the antibacterial rate of Ti/APS/GO/Cu against E. coli or S. aureus reached over 99%. Besides, Ti/APS/GO/Cu showed excellent biocompatibility and no toxicity to cell. Such work developed multiple sterilization avenues to design non-antibiotic, safe and efficient antibacterial implant material for the biomedical domain.

Antibacterial coatings on orthopedic implants

With the aging of population and the rapid improvement of public health and medical level in recent years, people have had an increasing demand for orthopedic implants. However, premature implant failure and postoperative complications frequently occur due to implant-related infections, which not only increase the social and economic burden, but also greatly affect the patient's quality of life, finally restraining the clinical use of orthopedic implants. Antibacterial coatings, as an effective strategy to solve the above problems, have been extensively studied and motivated the development of novel strategies to optimize the implant. In this paper, a variety of antibacterial coatings recently developed for orthopedic implants were briefly reviewed, with the focus on the synergistic multi-mechanism antibacterial coatings, multi-functional antibacterial coatings, and smart antibacterial coatings that are more potential for clinical use, thereby providing theoretical references for further fabrication of novel and high-performance coatings satisfying the complex clinical needs.

Biomimicry and 3D-Printing of Mussel Adhesive Proteins for Regeneration of the Periodontium-A Review

Innovation in the healthcare profession to solve complex human problems has always been emulated and based on solutions proven by nature. The conception of different biomimetic materials has allowed for extensive research that spans several fields, including biomechanics, material sciences, and microbiology. Due to the atypical characteristics of these biomaterials, dentistry can benefit from these applications in tissue engineering, regeneration, and replacement. This review highlights an overview of the application of different biomimetic biomaterials in dentistry and discusses the key biomaterials (hydroxyapatite, collagen, polymers) and biomimetic approaches (3D scaffolds, guided bone and tissue regeneration, bioadhesive gels) that have been researched to treat periodontal and peri-implant diseases in both natural dentition and dental implants. Following this, we focus on the recent novel application of mussel adhesive proteins (MAPs) and their appealing adhesive properties, in addition to their key chemical and structural properties that relate to the engineering, regeneration, and replacement of important anatomical structures in the periodontium, such as the periodontal ligament (PDL). We also outline the potential challenges in employing MAPs as a biomimetic biomaterial in dentistry based on the current evidence in the literature. This provides insight into the possible increased functional longevity of natural dentition that can be translated to implant dentistry in the near future. These strategies, paired with 3D printing and its clinical application in natural dentition and implant dentistry, develop the potential of a biomimetic approach to overcoming clinical problems in dentistry.

Advances and Prospects in Antibacterial-Osteogenic Multifunctional Dental Implant Surface

In recent years, dental implantation has become the preferred protocol for restoring dentition defects. Being the direct contact between implant and bone interface, osseointegration is the basis for implant exerting physiological functions. Nevertheless, biological complications such as insufficient bone volume, poor osseointegration, and postoperative infection can lead to implant failure. Emerging antibacterial-osteogenic multifunctional implant surfaces were designed to make up for these shortcomings both during the stage of forming osseointegration and in the long term of supporting the superstructure. In this mini-review, we summarized the recent antibacterial-osteogenic modifications of the dental implant surface. The effects of these modifications on biological performance like soft tissue integration, bone osteogenesis, and immune response were discussed. In addition, the clinical findings and prospects of emerging antibacterial-osteogenic implant materials were also discussed.

Heparinized anticoagulant coatings based on polyphenol-amine inspired chemistry for blood-contacting catheters

Blood-contacting catheters occupy a vital position in modern clinical treatment including but not limited to cardiovascular diseases, but catheter-related thrombosis associated with high morbidity and mortality remains a major health concern. Hence, there is an urgent need for functionalized catheter surfaces with superior hemocompatibility that prevent protein adsorption and thrombus formation. In this work, we developed a strategy for constructing a kind of polyphenol-amine coating on the TPU surface (TLA) with tannic acid and lysine via simple dip-coating, inspired by dopamine adhesion. Based on the long-term stability and modifiable properties of TLA coatings, heparin was introduced by an amide reaction to provide anticoagulant activity (TLH). X-ray photoelectron spectroscopy and surface zeta potential measurements fully indicated the successful immobilization of heparin. Water contact angle measurements demonstrated good hydrophilicity and stability for 15 days of TLH coatings. Furthermore, the TLH coatings exhibited significant hemocompatibility and no cytotoxicity. The good antithrombotic properties of the functionalized surfaces were confirmed by an ex vivo blood circulation model. The present work is supposed to find potential clinical applications for preventing surface-induced thrombosis of blood-contacting catheters.

A Naringin-loaded gelatin-microsphere/nano-hydroxyapatite/silk fibroin composite scaffold promoted healing of critical-size vertebral defects in ovariectomised rat

In this study, we investigated the effect of three-dimensional of naringin/gelatin microspheres/nano-hydroxyapatite/silk fibroin (NG/GMs/nHA/SF) scaffolds on repair of a critical-size bone defect of lumbar 6 in osteoporotic rats. In this work, a cell-free scaffold for bone-tissue engineering based on a silk fibroin (SF)/nano-hydroxyapatite (nHA) scaffold was developed. The scaffold was fabricated by lyophilization. Naringin (NG) was loaded into gelatin microspheres (GMs), which were encapsulated in the nHA/SF scaffolds. The materials were characterized using x ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. Moreover, the biomechanics, degradation, and drug-release profile of the scaffold were also evaluated. In vitro, the effect of the scaffold on the adhesion, proliferation, and osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) was evaluated. In vivo, at 3 months after ovariectomy, a critical-size lumbar defect was indued in the rats to evaluate scaffold therapeutic potential. A 3-mm defect in L6 developed in 60 SD rats, which were randomly divided into SF scaffold, nHA/SF scaffold, NG/nHA/SF scaffold, NG/GMs/nHA/SF scaffold, and blank groups (n = 12 each). At 4, 8, 12, and 16 weeks postoperatively, osteogenesis was evaluated by X-ray, micro-computed tomography, hematoxylin-eosin staining, and fast green staining, and by analysis of BMP-2, Runx2, and Ocn protein levels at 16 weeks. In our results, NG/GM/nHA/SF scaffolds exhibited good biocompatibility, biomechanical strength, and promoted BMSC adhesion, proliferation, and calcium nodule formation in vitro. Moreover, NG/GMs/nHA/SF scaffolds showed greater osteogenic differentiation potential than the other scaffolds in vitro. In vivo, gradual new bone formation was observed, and bone defects recovered by 16 weeks in the experimental group. In the blank group, limited bone formation was observed, and the bone defect was obvious. In conclusion, NG/GMs/nHA/SF scaffolds promoted repair of a lumbar 6 defect in osteoporotic rats. Therefore, the NG/GMs/nHA/SF biocomposite scaffold has potential as a bone-defect-filling biomaterial for bone regeneration.