Development and effect of different bioactive silicate glass scaffolds: In vitro evaluation for use as a bone drug delivery system

Improved Mechanical Properties and Bioactivity of Silicate Based Bioceramics Reinforced Poly(ether-ether-ketone) Nanocomposites for Prosthetic Dental Implantology

Polyether-ether-ketone (PEEK) biomaterial has been increasingly employed for orthopedic, trauma, spinal, and dental implants due to its biocompatibility and in vivo stability. However, a lack of bioactivity and binding ability to natural bone tissue has significantly limited PEEK for many challenging dental implant applications. In this work, nanocomposites based on PEEK reinforced with bioactive silicate-based bioceramics (forsterite or bioglass) as nanofillers were prepared using high energy ball milling followed by melt blending and compression molding. The influence of nanofillers type and content (10, 20 and 30 wt.%) on the crystalline structure, morphology, surface roughness, hydrophilicity, microhardness, elastic compression modulus, and flexural strength of the nanocomposites was investigated. The scanning electron microscopy images of the nanocomposites with low nanofillers content showed a homogenous surface with uniform dispersion within the PEEK matrix with no agglomerates. All nanocomposites showed an increased surface roughness compared to pristine PEEK. It was found that the incorporation of 20 wt.% forsterite was the most effective in the nanocomposite formulation compared with bioglass-based nanocomposites; it has significantly improved the elastic modulus, flexural strength, and microhardness. In vitro bioactivity evaluation, which used biomimetic simulated body fluid indicated the ability of PEEK nanocomposites loaded with forsterite or bioglass nanofillers to precipitate calcium and phosphate bone minerals on its surface. These nanocomposites are expected to be used in long-term load-bearing implant applications and could be recommended as a promising alternative to titanium and zirconia when used as a dental implant material.

Comprehensive Survey on Nanobiomaterials for Bone Tissue Engineering Applications

One of the most important ideas ever produced by the application of materials science to the medical field is the notion of biomaterials. The nanostructured biomaterials play a crucial role in the development of new treatment strategies including not only the replacement of tissues and organs, but also repair and regeneration. They are designed to interact with damaged or injured tissues to induce regeneration, or as a forest for the production of laboratory tissues, so they must be micro-environmentally sensitive. The existing materials have many limitations, including impaired cell attachment, proliferation, and toxicity. Nanotechnology may open new avenues to bone tissue engineering by forming new assemblies similar in size and shape to the existing hierarchical bone structure. Organic and inorganic nanobiomaterials are increasingly used for bone tissue engineering applications because they may allow to overcome some of the current restrictions entailed by bone regeneration methods. This review covers the applications of different organic and inorganic nanobiomaterials in the field of hard tissue engineering.

Multifunctional zinc ion doped sol - gel derived mesoporous bioactive glass nanoparticles for biomedical applications

Mesoporous bioactive glasses have been widely investigated for applications in bone tissue regeneration and, more recently, in soft tissue repair and wound healing. In this study we produced mesoporous bioactive glass nanoparticles (MBGNs) based on the SiO2-CaO system. With the intention of adding subsidiary biological function, MBGNs were doped with Zn2+ ions. Zn-MBGNs with 8 mol% ZnO content were synthesized via microemulsion assisted sol-gel method. The synthesized particles were homogeneous in shape and size. They exhibited spherical shape, good dispersity, and a size of 130 ± 10 nm. The addition of zinc precursors did not affect the morphology of particles, while their specific surface area increased in comparison to MBGNs. The presence of Zn2+ ions inhibited the formation of hydroxycarbonate apatite (HCAp) on the particles after immersion in simulated body fluid (SBF). No formation of HCAp crystals on the surface of Zn-MBGNs could be observed after 14 days of immersion. Interestingly, powders containing relatively high amount of zinc released Zn2+ ions in low concentration (0.6-1.2 mg L-1) but in a sustained manner. This releasing feature enables Zn-MBGNs to avoid potentially toxic levels of Zn2+ ions, indeed Zn-MBGNs were seen to improve the differentiation of osteoblast-like cells (MG-63). Additionally, Zn-MBGNs showed higher ability to adsorb proteins in comparison to MBGNs, which could indicate a favourable later attachment of cells. Due to their advantageous morphological and physiochemical properties, Zn-MBGNs show great potential as bioactive fillers or drug delivery systems in a variety of applications including bone regeneration and wound healing.

Chronic Osteomyelitis - Bacterial Flora, Antibiotic Sensitivity and Treatment Challenges

Background:

Chronic osteomyelitis is a catastrophic sequel of delayed diagnosis of acute osteomyelitis.

Objectives:

The objectives of the study were to determine bacterial flora and antibiotic sensitivity, and to evaluate the outcome of an aggressive surgical approach to chronic osteomyelitis.

Methods:

This is a single surgeon, prospective cohort study on 30 consecutive patients with clinically and radiologically diagnosed chronic osteomyelitis presented to a hospital. We prospectively recorded demographic, clinical, radiological features, treatment protocol, microbiologic results of culture and sensitivity. The main treatment outcome measures were clinical signs of eradication of infection.

Results:

Microbiologic results showed that Gram-negative and mixed flora accounts for more than half of chronic osteomyelitis cases while Staphylococcus aureus was a dominating single pathogen (39%). We detected a high resistance rate to common antibiotics, e.g. 83% of S. aureus isolates were resistant to oxacillin (MRSA). The mean duration of bone infection was 4.2 years (3 months to 30 years) and the mean number of operations was 1.5 (1-5) . The mean follow-up was 15 months (12-18 months). Infection was eradicated in 95% (21 out of 22) treated by a single procedure and in all patients (n=8) by double procedure.

Conclusion:

Presented the high rate of MRSA strains is alarming and calls for updating of the antibiotic therapy guidelines in the country. Good results in treatment of chronic osteomyelitis can be achieved by a single-stage protocol including radical debridement combined with systemic and topical antibiotic.

Bioactive glasses as delivery systems for antimicrobial agents

Most biomaterial-associated infections are caused by opportunistic pathogens and bacteria that are regularly found within the microflora of the implant site. In addition, a biomaterial implant or device remains at risk of infection by hematogenous spread of bacteria disseminated from infections elsewhere in the body or from infected peri-implant tissue in revision surgery. The resulting infections are frequently accompanied by patient morbidity and discomfort and can lead to surgical replacement of the implant after lengthy, unsuccessful attempts to mitigate infections with antibiotic treatments. Therefore, extensive study is aiming to find new infection-resistant antimicrobial biomaterials and coatings for implants and devices to effectively reduce the incidence of biomaterial-associated infections. An overview of the in vitro and in vivo antimicrobial efficacies of the numerous biomaterials currently available is beyond the scope of this review. Herein, we provide a comprehensive review of bioactive glasses as biomaterial delivery systems for antimicrobial agents.

Novel antibacterial bioactive glass nanocomposite functionalized with tetracycline hydrochloride

To prevent the high frequency of wound infections, anti-bacterial agents can be loaded onto composites. In the present study, the antibiotic tetracycline hydrochloride (TC)was incorporated, for the first time, in collagen type I membranes coated with nano-sized SiO2-CaOP2O5 bioactive glass (n-BG) obtained by a sol-gel chemical route.

Collagen membranes coated with n-BG were immersed in simulated body fluid (SBF) containing 0.25, 0.75 or 1.25 mg mL−1 of TC for 48 h at 37∘C following a coprecipitation method. The antibiotic was released in distilledwater at 37∘C for up to 72 h. The antibacterial activity of the composites was evaluated in vitro by the inhibition zone test and plate count method. Two different Staphylococcus aureus strains, S. aureus ATCC29213 and S. aureus ATCC25923, were exposed to the biomaterials. The results showed that the incorporation but not the release of TC was dependent on the initial concentration of TC in SBF. The biomaterials inhibited S. aureus growth, although the efficacy was similar for all the concentrations. The results allow us to conclude that the new composite could have potential in the prevention of wound infections.

Zinc-containing bioactive glasses for bone regeneration, dental and orthopedic applications

Zinc is a vital and beneficial trace element found in the human body. Though found in small proportions, zinc performs a variety of functions in relation to the immune system, cell division, fertility and the body growth and maintenance. In particular, zinc is proven to be a necessary element for the formation, mineralization, development and maintenance of healthy bones. Considering this attractive attributes of zinc, recent research has widely focused on using zinc along with silicate-based bioactive glasses for bone tissue engineering applications. This paper reviews relevant literature discussing the significance of zinc in the human body, along with its ability to enhance antibacterial effects, bioactivity and distinct physical, structural and mechanical properties of bioactive glasses. In this context, even if the present analysis is not meant to be exhaustive and only representative studies are discussed, literature results confirm that it is essential to understand the properties of zinc-containing bioactive glasses with respect to their in vitro biological behavior, possible cytotoxic effects and degradation characteristics to be able to effectively apply these glasses in bone regeneration strategies. Topics attracting increasing research efforts in this field are elaborated in detail in this review, including a summary of the structural, physical, biological and mechanical properties of zinc-containing bioactive glasses. This paper also presents an overview of the various applications in which zinc-containing bioactive glasses are considered for use as bone tissue scaffolds, bone filling granules, bioactive coatings and bone cements, and advances and remaining challenges are highlighted.