Doxycycline-loaded coaxial nanofiber coating of titanium implants enhances osseointegration and inhibits Staphylococcus aureus infection

Therapeutic Efficacy of an Erythromycin-Loaded Coaxial Nanofiber Coating in a Rat Model of S. aureus-Induced Periprosthetic Joint Infection

Implant surface nanofiber (NF) coatings represent an alternative way to prevent/treat periprosthetic joint infection (PJI) via local drug release. We developed and characterized a coaxial erythromycin (EM)-doped PLGA/PCL-PVA NF coating. The purpose of this study was to determine the efficacy of EM-NF coatings (EM0, no EM, EM100 (100 mg/mL), and EM1000 (1000 mg/mL) wt/wt) in a rat PJI model. A strong bond of the EM-NF coating to the surface of titanium (Ti) pins was confirmed by in vitro mechanical testing. Micro-computed tomography (mCT) analysis showed that both EM100 and EM1000 NF effectively reduced periprosthetic osteolysis compared to EM0 at 8 and 16 weeks after implantation. Histology showed that EM100 and EM1000 coatings effectively controlled infection and enhanced periprosthetic new bone formation. The bone implant contact (BIC) of EM100 (35.08%) was higher than negative controls and EM0 (3.43% and 0%, respectively). The bone area fraction occupancy (BAFO) of EM100 (0.63 mm2) was greater than controls and EM0 (0.390 mm2 and 0.0 mm2, respectively). The BAFO of EM100 was higher than that of EM1000 (0.3 mm2). These findings may provide a basis for a new implant surface fabrication strategy aimed at reducing the risks of defective osseointegration and PJI.

A review on antimicrobial strategies in mitigating biofilm-associated infections on medical implants

Biomedical implants are crucial in providing support and functionality to patients with missing or defective body parts. However, implants carry an inherent risk of bacterial infections that are biofilm-associated and lead to significant complications. These infections often result in implant failure, requiring replacement by surgical restoration. Given these complications, it is crucial to study the biofilm formation mechanism on various biomedical implants that will help prevent implant failures. Therefore, this comprehensive review explores various types of implants (e.g., dental implant, orthopedic implant, tracheal stent, breast implant, central venous catheter, cochlear implant, urinary catheter, intraocular lens, and heart valve) and medical devices (hemodialyzer and pacemaker) in use. In addition, the mechanism of biofilm formation on those implants, and their pathogenesis were discussed. Furthermore, this article critically reviews various approaches in combating implant-associated infections, with a special emphasis on novel non-antibiotic alternatives to mitigate biofilm infections.

An update on the advances in the field of nanostructured drug delivery systems for a variety of orthopedic applications

Nanotechnology has made significant progress in various fields, including medicine, in recent times. The application of nanotechnology in drug delivery has sparked a lot of research interest, especially due to its potential to revolutionize the field. Researchers have been working on developing nanomaterials with distinctive characteristics that can be utilized in the improvement of drug delivery systems (DDS) for the local, targeted, and sustained release of drugs. This approach has shown great potential in managing diseases more effectively with reduced toxicity. In the medical field of orthopedics, the use of nanotechnology is also being explored, and there is extensive research being conducted to determine its potential benefits in treatment, diagnostics, and research. Specifically, nanophase drug delivery is a promising technique that has demonstrated the capability of delivering medications on a nanoscale for various orthopedic applications. In this article, we will explore current advancements in the area of nanostructured DDS for orthopedic use.

Novel PVAMA/GelMA aerogels prepared by liquid-phase collection of photoinitiated polymerisation: injectable and flowable low-density 3D scaffolds for bone regeneration

Nanofibrous scaffolds, which are morphologically/structurally similar to native extracellular matrix, are ideal biomaterials for tissue engineering and regenerative medicine. However, the use of traditional electrospinning techniques to produce three-dimensional (3D) nanofibrous scaffolds with desired structural properties presents difficulty. To address this challenge, we prepared a novel liquid-phase-collected photoinitiated polymerised aerogel 3D scaffold (LPPI-AG) using the thermally induced (nanofiber) self-aggregation method after liquid-phase electrospinning of the hydroxyapatite-doped methacrylated polyvinyl alcohol/methacrylated gelatine solution obtained by photoinitiated polymerisation. The fabricated aerogel scaffolds had a high porosity of approximately 99.01% ± 0.40% and an interconnected network structure with pore sizes ranging from submicron to ∼300 μm. The new aerogel rapidly became flowable when exposed to a solution, and it can fill gaps and repair gap edges effectively and be loaded with nutrients and growth factors that promote bone growth for bone tissue engineering. LPPI-AG scaffolds can considerably promote osteogenic differentiation of bone marrow mesenchymal stem cells in vitro. Furthermore, in vivo studies showed that the LPPI-AG scaffold significantly promoted bone formation in a mouse model of critical-size calvarial defects.

Biopolymeric Coatings for Local Release of Therapeutics from Biomedical Implants

The deployment of structures that enable localized release of bioactive molecules can result in more efficacious treatment of disease and better integration of implantable bionic devices. The strategic design of a biopolymeric coating can be used to engineer the optimal release profile depending on the task at hand. As illustrative examples, here advances in delivery of drugs from bone, brain, ocular, and cardiovascular implants are reviewed. These areas are focused to highlight that both hard and soft tissue implants can benefit from controlled localized delivery. The composition of biopolymers used to achieve appropriate delivery to the selected tissue types, and their corresponding outcomes are brought to the fore. To conclude, key factors in designing drug-loaded biopolymeric coatings for biomedical implants are highlighted.

Recent Advancements in Metallic Drug-Eluting Implants

Over the past decade, metallic drug-eluting implants have gained significance in orthopedic and dental applications for controlled drug release, specifically for preventing infection associated with implants. Recent studies showed that metallic implants loaded with drugs were substituted for conventional bare metal implants to achieve sustained and controlled drug release, resulting in a desired local therapeutic concentration. A number of secondary features can be provided by the incorporated active molecules, including the promotion of osteoconduction and angiogenesis, the inhibition of bacterial invasion, and the modulation of host body reaction. This paper reviews recent trends in the development of the metallic drug-eluting implants with various drug delivery systems in the past three years. There are various types of drug-eluting implants that have been developed to meet this purpose, depending on the drug or agents that have been loaded on them. These include anti-inflammatory drugs, antibiotics agents, growth factors, and anti-resorptive drugs.

Electrospun hybrid nanofibers: Fabrication, characterization, and biomedical applications

Nanotechnology is one of the most promising technologies available today, holding tremendous potential for biomedical and healthcare applications. In this field, there is an increasing interest in the use of polymeric micro/nanofibers for the construction of biomedical structures. Due to its potential applications in various fields like pharmaceutics and biomedicine, the electrospinning process has gained considerable attention for producing nano-sized fibers. Electrospun nanofiber membranes have been used in drug delivery, controlled drug release, regenerative medicine, tissue engineering, biosensing, stent coating, implants, cosmetics, facial masks, and theranostics. Various natural and synthetic polymers have been successfully electrospun into ultrafine fibers. Although biopolymers demonstrate exciting properties such as good biocompatibility, non-toxicity, and biodegradability, they possess poor mechanical properties. Hybrid nanofibers from bio and synthetic nanofibers combine the characteristics of biopolymers with those of synthetic polymers, such as high mechanical strength and stability. In addition, a variety of functional agents, such as nanoparticles and biomolecules, can be incorporated into nanofibers to create multifunctional hybrid nanofibers. Due to the remarkable properties of hybrid nanofibers, the latest research on the unique properties of hybrid nanofibers is highlighted in this study. Moreover, various established hybrid nanofiber fabrication techniques, especially the electrospinning-based methods, as well as emerging strategies for the characterization of hybrid nanofibers, are summarized. Finally, the development and application of electrospun hybrid nanofibers in biomedical applications are discussed.

Functional engineering strategies of 3D printed implants for hard tissue replacement

Three-dimensional printing technology with the rapid development of printing materials are widely recognized as a promising way to fabricate bioartificial bone tissues. In consideration of the disadvantages of bone substitutes, including poor mechanical properties, lack of vascularization and insufficient osteointegration, functional modification strategies can provide multiple functions and desired characteristics of printing materials, enhance their physicochemical and biological properties in bone tissue engineering. Thus, this review focuses on the advances of functional engineering strategies for 3D printed biomaterials in hard tissue replacement. It is structured as introducing 3D printing technologies, properties of printing materials (metals, ceramics and polymers) and typical functional engineering strategies utilized in the application of bone, cartilage and joint regeneration.

An overview on electrospinning and its advancement toward hard and soft tissue engineering applications

One of the emerging technologies of the recent times harboring nanotechnology to fabricate nanofibers for various biomedical and environmental applications are electrospinning (nanofiber technology). Their relative ease in use, simplicity, functionality and diversity has surpassed the pitfalls encountered with the conventional method of generating fibers. This review aims to provide an overview of electrospinning, principle, methods, feed materials, and applications toward tissue engineering. To begin with, evolution of electrospinning and its typical apparatus have been briefed. Simultaneously, discussion on the production of nanofibers with diversified feed materials such as polymers, small molecules, colloids, and nanoparticles and its transformation into a powerful technology has been dealt with. Further, highlights on the application of nanofibers in tissue engineering and the commercialized products developed using nanofiber technology have been summed up. With this rapidly emerging technology, there would be a great demand pertaining to scalability and environmental challenge toward tissue engineering applications.

Osteoblastic differentiation and bactericidal activity are enhanced by erythromycin released from PCL/PLGA-PVA coaxial nanofibers

Prosthesis with antibiotic-eluting nanofibrous (NF) coating represents coating alternative to prevent periprosthetic joint infection (PJI). In this study, four formulas of erythromycin (EM)-embedded both in core and sheath components of coaxial PCL/PLGA-PVA NF coatings were developed: EM 0 (no EM), EM 100 (100 μg/mL), EM500 (500 μg/mL) and EM1000 (1000 μg/mL). EM doping altered the physicochemical and structural properties of NFs to some extent, including the increase of NF porosity and surface wettability. A sustained EM release from EM-NFs for >4 weeks was observed. Eluents collected from EM-NFs showed strong zone of inhibition (ZOI) to Staphylococcus aureus growth and the sizes of ZOI positively related to the amount of EM released. EM-NFs were nontoxic to rat bone marrow stem cells (rBMSCs). Cell growth was significantly enhanced when comparing rBMSCs cultured on EM-NFs (EM0 and EM 100) to those cultured on NF-free control. Cell differentiation (ALP activity) was notably enhanced by EM100, compared to control and EM0. Eluents from EM-NFs on rBMSCs were also investigated. The presence of 10% EM-NF eluents inhibited the growth of rBMSCs, which was proportional to the amount of EM doped. The ALP activity was notably enhanced by eluents from EM-NFs with the highest activity in EM100 compared to control and EM0. Our data indicate that EM-doped PCL/PLGA-PVA coaxial NF coatings have a great potential to be applied as a new implant coating matrices. Further in vivo testing in animal models is currently planned that should represent the first step in predicting the clinical outcomes of EM-eluting NF coating approach.

Construction of Local Drug Delivery System on Titanium-Based Implants to Improve Osseointegration

Titanium and its alloys are the most widely applied orthopedic and dental implant materials due to their high biocompatibility, superior corrosion resistance, and outstanding mechanical properties. However, the lack of superior osseointegration remains the main obstacle to successful implantation. Previous traditional surface modification methods of titanium-based implants cannot fully meet the clinical needs of osseointegration. The construction of local drug delivery systems (e.g., antimicrobial drug delivery systems, anti-bone resorption drug delivery systems, etc.) on titanium-based implants has been proved to be an effective strategy to improve osseointegration. Meanwhile, these drug delivery systems can also be combined with traditional surface modification methods, such as anodic oxidation, acid etching, surface coating technology, etc., to achieve desirable and enhanced osseointegration. In this paper, we review the research progress of different local drug delivery systems using titanium-based implants and provide a theoretical basis for further research on drug delivery systems to promote bone–implant integration in the future.

Nanofiber Polymers for Coating Titanium-Based Biomedical Implants

The excellent combination of properties has seen a steep increase in the demand for titanium (Ti)-based material as biomedical implant devices. However, some features that promote biocompatibility are found to be lacking in Ti implants. The use of polymer nanofiber (NF) coating on the surfaces of the implants has been proven to remedy these setbacks. In particular, electrospun NFs are versatile as natural extracellular matrix mimics and as facilitators in the biocompatibility function of Ti-based implants. Therefore, various properties of Ti implants coated with polymer NFs and the correlations among these properties are explored in this review. Synthetic polymers are favorable in tissue engineering applications because they are biocompatible and have low toxicity and degradation rates. Several approved synthetic polymers and polymer hybrids have been electrospun onto Ti implant surfaces to successfully improve the biomedical applicability of the implants with regard to their physical (including diameter and porosity), chemical (including corrosion resistance), mechanical (including elastic modulus, strength and ductility) and biological properties (including tissue integration, antimicrobial and cytotoxicity).

Electrospun Nanofibers Revisited: An Update on the Emerging Applications in Nanomedicine

Electrospinning (ES) has become a straightforward and customizable drug delivery technique for fabricating drug-loaded nanofibers (NFs) using various biodegradable and non-biodegradable polymers. One of NF's pros is to provide a controlled drug release through managing the NF structure by changing the spinneret type and nature of the used polymer. Electrospun NFs are employed as implants in several applications including, cancer therapy, microbial infections, and regenerative medicine. These implants facilitate a unique local delivery of chemotherapy because of their high loading capability, wide surface area, and cost-effectiveness. Multi-drug combination, magnetic, thermal, and gene therapies are promising strategies for improving chemotherapeutic efficiency. In addition, implants are recognized as an effective antimicrobial drug delivery system overriding drawbacks of traditional antibiotic administration routes such as their bioavailability and dosage levels. Recently, a sophisticated strategy has emerged for wound healing by producing biomimetic nanofibrous materials with clinically relevant properties and desirable loading capability with regenerative agents. Electrospun NFs have proposed unique solutions, including pelvic organ prolapse treatment, viable alternatives to surgical operations, and dental tissue regeneration. Conventional ES setups include difficult-assembled mega-sized equipment producing bulky matrices with inadequate stability and storage. Lately, there has become an increasing need for portable ES devices using completely available off-shelf materials to yield highly-efficient NFs for dressing wounds and rapid hemostasis. This review covers recent updates on electrospun NFs in nanomedicine applications. ES of biopolymers and drugs is discussed regarding their current scope and future outlook.

Antibiotics- and Heavy Metals-Based Titanium Alloy Surface Modifications for Local Prosthetic Joint Infections

Prosthetic joint infection (PJI) is the second most common cause of arthroplasty failure. Though infrequent, it is one of the most devastating complications since it is associated with great personal cost for the patient and a high economic burden for health systems. Due to the high number of patients that will eventually receive a prosthesis, PJI incidence is increasing exponentially. As these infections are provoked by microorganisms, mainly bacteria, and as such can develop a biofilm, which is in turn resistant to both antibiotics and the immune system, prevention is the ideal approach. However, conventional preventative strategies seem to have reached their limit. Novel prevention strategies fall within two broad categories: (1) antibiotic- and (2) heavy metal-based surface modifications of titanium alloy prostheses. This review examines research on the most relevant titanium alloy surface modifications that use antibiotics to locally prevent primary PJI.

Effectiveness of Antibacterial Surfaces in Osseointegration of Titanium Dental Implants: A Systematic Review

Titanium (Ti) dental implant failure as a result of infection has been established at 40%, being regarded as one of the most habitual and untreatable problems. Current research is focused on the design of new surfaces that can generate long-lasting, infection-free osseointegration. The purpose of our study was to assess studies on Ti implants coated with different antibacterial surfaces, assessing their osseointegration. The PubMed, Web of Science and Scopus databases were electronically searched for in vivo studies up to December 2020, selecting six studies that met the inclusion criteria. The quality of the selected studies was assessed using the ARRIVE (Animal Research: Reporting of In Vivo Experiments) criteria and Systematic Review Center for Laboratory animal Experimentation's (SYRCLE's) risk of bias tool. Although all the included studies, proved greater osseointegration capacity of the different antibacterial surfaces studied, the methodological quality and experimental models used in some of them make it difficult to draw predictable conclusions. Because of the foregoing, we recommend caution when interpreting the results obtained.

Targeting implant-associated infections: titanium surface loaded with antimicrobial

Implant devices have = proven a successful treatment modality in reconstructive surgeries. However, increasing rates of peri-implant diseases demand further examination of their pathogenesis. Polymicrobial biofilm formation on titanium surfaces has been considered the main risk factor for inflammatory processes on tissues surrounding implant devices, which often lead to implant failure. To overcome microbial accumulation on titanium surfaces biofilm targeting strategies have been developed to modify the surface and incorporate antimicrobial coatings. Because antibiotics are widely used to treat polymicrobial infections, these agents have recently started to be incorporated on titanium surface. This review discusses the biofilm formation on titanium dental implants and key factors to be considered in therapeutic and preventative strategies. Moreover, a systematic review was conducted on coatings developed for titanium surfaces using different antibiotics. This review will also shed light on potential alternative strategies aiming to reduce microbial loads and control polymicrobial infection on implanted devices.

Nanotechnology-based drug delivery systems in orthopedics

In recent years, nanotechnology has led to significant scientific and technological advances in diverse fields, specifically within the field of medicine. Owing to the revolutionary implications in drug delivery, nanotechnology-based drug delivery systems have gained an increasing research interest in the current medical field. A variety of nanomaterials with unique physical, chemical and biological properties have been engineered to develop new drug delivery systems for the local, sustained and targeted delivery of drugs with improved therapeutic efficiency and less or no toxicity, representing a very promising approach for the effective management of diseases. The utility of nanotechnology, particularly in the field of orthopedics, is a topic of extensive research. Nanotechnology has a great potential to revolutionize treatment, diagnostics, and research in the field of orthopedics. Nanophase drug delivery has shown great promise in their ability to deliver drugs at nanoscale for a variety of orthopedic applications. In this review, we discuss recent advances in the field of nanostructured drug delivery systems for orthopedic applications.

Doxycycline and Zinc Loaded Silica-Nanofibrous Polymers as Biomaterials for Bone Regeneration

The main target of bone tissue engineering is to design biomaterials that support bone regeneration and vascularization. Nanostructured membranes of (MMA)₁-co-(HEMA)₁/(MA)₃-co-(HEA)₂ loaded with 5% wt of SiO₂-nanoparticles (HOOC-Si-Membrane) were doped with zinc (Zn-HOOC-Si-Membrane) or doxycycline (Dox-HOOC-Si-Membrane). Critical bone defects were effectuated on six New Zealand-bred rabbit skulls and covered with the membranes. After six weeks, the bone architecture was evaluated with micro computed tomography. Three histological analyses were utilized to analyse bone regeneration, including von Kossa silver nitrate, toluidine blue and fluorescence. All membrane-treated defects exhibited higher number of osteocytes and bone perimeter than the control group without the membrane. Zn-HOOC-Si-Membranes induced higher new bone and osteoid area than those treated with HOOC-Si-Membranes, and control group, respectively. Zn-HOOC-Si-Membranes and Dox-HOOC-Si-Membranes attained the lowest ratio M1 macrophages/M2 macrophages. Dox-HOOC-Si-Membranes caused the lowest number of osteoclasts, and bone density. At the trabecular new bone, Zn-HOOC-Si-Membranes produced the highest angiogenesis, bone thickness, connectivity, junctions and branches. Zn-HOOC-Si-Membranes enhanced biological activity, attained a balanced remodeling, and achieved the greatest regenerative efficiency after osteogenesis and angiogenesis assessments. The bone-integrated Zn-HOOC-Si-Membranes can be considered as bioactive modulators provoking a M2 macrophages (pro-healing cells) increase, being a potential biomaterial for promoting bone repair.

Photobiomodulation (450 nm) alters the infection of periodontitis bacteria via the ROS/MAPK/mTOR signaling pathway

We aimed to investigate the effects of photobiomodulation (PBM) on periodontitis. A periodontitis model was established via Porphyromonas gingivalis infection in beagles. Mandibular second and third premolars were removed, and implants were positioned immediately after tooth extraction. Left gingiva was irradiated with PBM (450 nm) as the LG group, and right side without irradiation was regarded as the CG (control) group. PBM treatment increased oxidative stress by increasing the levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The elevated levels of H₂O₂ (a biomarker of oxidative stress) and the free radicals (NO^• and O₂^•-) reduced the concentration of dominant pathogens and regulated ROS/RNS/AMP-activated protein kinase (AMPK)/mTOR pathway by affecting p-AMPK, Runt-related transcription factor 2 (RUNX2), p-c-Jun N-terminal kinase (JNK)/mammalian target of rapamycin (mTOR), and acetyl-CoA carboxylase 1 (ACC1). PBM therapy increased salivary levels of interleukin-1 receptor antagonist (IL-1ra), interleukin (IL)-10, total antioxidant capacity (TAC) and catalase (CAT), and reduced the levels of tumor necrosis factor (TNF)α and interleukin (IL)-1β, malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) (p < 0.05). All the results contributed to preventing periodontitis infection. PBM therapy improved bone mineral density and implant osseointegration by controlling dominant pathogens invasion via the upregulation of salivary anti-inflammatory and antioxidant defense by affecting ROS/RNS/AMPK/mTOR signaling pathway.

Targeted Drug Delivery from Titanium Implants: A Review of Challenges and Approaches

Titanium implants are considered the gold standard of treatment for dental and orthopedic applications. Biocompatibility, low elasticity, and corrosion resistance are some of the key properties of these metallic implants. Nonetheless, a long-term clinical failure of implants may occur due to inadequate osseointegration. Poor osseointegration induces mobility, inflammation, increased bone resorption, and osteolysis; hence, it may result in painful revision surgeries. Topographical modifications, improvement in hydrophilicity, and the development of controlled-release drug-loading systems have shown to improve cellular adhesion, proliferation, and differentiation. Surface modifications, along with drug coating, undoubtedly demonstrate better osseointegration, especially in challenged degenerative conditions, such as osteoporosis, osteoarthritis, and osteogenesis imperfecta. Anabolic bone-acting drugs, such as parathyroid hormone peptides, simvastatin, prostaglandin-EP4-receptor antagonist, vitamin D, strontium ranelate, and anti-catabolic bone-acting drugs, such as calcitonin, bisphosphonates, and selective estrogen receptor modulators, expedite the process of osseointegration. In addition, various proteins, peptides, and growth factors may accessorize the idea of localized therapy. Loading these substances on modified titanium surfaces is achieved commonly by mechanisms such as direct coating, adsorption, and incorporating in biodegradable polymers. The primary approach toward the optimum drug loading is a critical trade-off between factors preventing release of a drug immediately and those allowing slow and sustained release. Recent advances broaden the understanding of the efficacy of adsorption, hydrogel coating, and electrospinning layer-by-layer coating facilitated by differential charge on metallic surface. This review discusses the existing approaches and challenges for the development of stable and sustained drug delivery systems on titanium implants, which would promote faster and superior osseointegration.

A doxycycline-treated hydroxyapatite implant surface attenuates the progression of peri-implantitis: A radiographic and histological study in mice

BACKGROUND

Oral rehabilitation with dental implants has become increasingly common; however, the increase of peri-implantitis is a great concern. Doxycycline (DOX) is a widely used antibiotic that inhibits bacteria growth, inflammation, and bone resorption.

OBJECTIVES

To evaluate the progression of peri-implantitis of hydroxyapatite (HA)-coated implants with (5 mg/mL, DOX group) or without (HA group) DOX treatment on the surface.

MATERIALS AND METHODS

The maxillary first molars of 20 male mice were extracted. Eight weeks later, small titanium screw implants coated with thin HA and treated with or without DOX were placed at the extracted sites. Four weeks after implant placement, half of the animals in both groups were sacrificed, and ligatures were placed around the implant necks in the other half. These mice were sacrificed 4 weeks later. The bone around the implants was examined radiologically and histologically.

RESULTS

Four weeks after the ligature placement, the radiographic measurements revealed that peri-implant bone levels of palatal and mesial sites, and histological measurements showed that bone levels of mesial and distal sites in the DOX group were significantly higher than those in the HA group.

CONCLUSIONS

The present results indicating that the DOX-treated HA implant surface attenuates the progression of peri-implantitis.