Uwe Gbureck

University of Wuerzburg | JMU · Department for Functional Materials in Medicine and Dentistry

In clinical practice, hydroxyapatite (HA) cements for bone defect treatment are frequently prepared by mixing a powder component and a liquid component shortly before implantation in the operation theater, which is time-consuming and error-prone. In addition, HA cements are only slightly resorbed, that is, cement residues can still be found in the...

Present surgical situations require a bone adhesive which has not yet been developed for use in clinical applications. Recently, phosphoserine modified cements (PMC) based on mixtures of o-phosphoserine (OPLS) and calcium phosphates, such as tetracalcium phosphate (TTCP) or α-tricalcium phosphate (α-TCP) as well as chelate setting magnesium phospha...

Objectives Synthetic bone substitutes which can be adapted preoperatively and patient specific may be helpful in various bony defects in the field of oral- and maxillofacial surgery. For this purpose, composite grafts made of self-setting and oil-based calcium phosphate cement (CPC) pastes, which were reinforced with 3D-printed polycaprolactone (PC...

Augmenting the vascular supply to generate new tissues, a crucial aspect in regenerative medicine, has been challenging. Recently, our group showed that calcium phosphate can induce the formation of a functional neo-angiosome without the need for microsurgical arterial anastomosis. This was a preclinical proof of concept for biomaterial-induced lum...

Digital light processing (DLP) enables the fabrication of complex 3D structures based on a photopolymerizable resin usually containing a photo initiator and an UV or photo absorber. The resin and thus the final properties of the printed structures can be adjusted by adding fillers like bioceramic powders relevant for bone regeneration applications....

Results of several studies during past years suggested that magnesium phosphate cements (MPCs) not only show excellent biocompatibility and osteoconductivity, but they also provide improved regeneration capacity due to higher solubility compared to calcium phosphates. These findings also highlighted that chemical similarity of bone substitutes to t...

As central part of the innate immune response, immune cells fight against invaders through various mechanisms, such as the release of extracellular traps (ETs). While this mechanism is mainly known for neutrophils in biomaterial contact, the release of macrophage extracellular traps (METs) in response to biomaterials has not yet been reported. An i...

A novel dual setting brushite-gelatin cement was achieved by genip ininitiated cross-linking of gelatin during cement setting. Although the combination of an inorganic and organic phase resulted in a decrease of the compressive strength from about 10 MPa without polymeric phase to 3–6–MPa for gelatin modified composites, an increase in elastic prop...

Objectives Magnesium phosphate–based cements begin to catch more attention as bone substitute materials and especially as alternatives for the more commonly used calcium phosphates. In bone substitutes for augmentation purposes, atraumatic materials with good biocompatibility and resorbability are favorable. In the current study, we describe the in...

The standard preparation routine of a calcium phosphate cement includes mixing a solid and a liquid component (reactive cement powder and mixing liquid) in an open bowl at the operating theatre. This poses the risk of preparation-related deviations of the resulting properties when the cements are mixed by different persons. Hence, facilitating this...

Background Suture anchors have a large field of application in orthopedic trauma surgery like the refixation of patellar, quadriceps and Achilles tendon or the treatment of rotator cuff tears. The fixation of suture anchors in osteoporotic bone is difficult, a problem that becomes increasingly relevant in the elderly. Methods Two types of suture a...

Zinc (Zn2+) is considered as an important mediator for thrombosis and haemostasis. However, our understanding of the transport mechanisms that regulate Zn2+ homeostasis in platelets is limited. Zn2+ transporters, ZIPs and ZnTs, are widely expressed in eukaryotic cells. Using mice globally lacking ZIP1 and ZIP3 (ZIP1/3 DKO), our aim was to explore t...

The long setting time and insufficient strength of tricalcium silicate (TCS)-based cements are a main disadvantage for their clinical use. Therefore, the aim of this study was to develop an advanced TCS cement by incorporating polydopamine (PDA) nanoparticles. The setting time and compressive strength of TCS cement with incorporated PDA nanoparticl...

This study aimed to develop printable calcium magnesium phosphate pastes that harden by immersion in ammonium phosphate solution post-printing. Besides the main mineral compound, biocompatible ceramic, magnesium oxide and hydroxypropylmethylcellulose (HPMC) were the crucial components. Two pastes with different powder to liquid ratios of 1.35 g/mL...

The study aims to highlight the importance of the process parameter choice during directional solidification of polymer solutions, as they have a significant influence on the pore structure and orientation. Biopolymer solutions (alginate and chitosan) are directionally frozen while systematically varying parameters such as the external temperature...

Aligned porous non‐sintered and sintered a‐tricalcium phosphate (a‐TCP) scaffolds are prepared by ice‐templating and converted into the low‐temperature calcium phosphates calcium‐deficient hydroxyapatite (CDHA), brushite and monetite. This is achieved by hydrothermal treatment or incubation in phosphoric acid solution and has a high clinical potent...

Clinically used mineral bone cements lack high strength values, absorbability and drillability. Therefore, magnesium phosphate cements have recently received increasing attention as they unify a high mechanical performance with presumed degradation in vivo. To obtain a drillable cement formulation, farringtonite (Mg3(PO4)2) and magnesium oxide (MgO...

This review recognizes a unique calcium phosphate (CaP) phase known as monetite or dicalcium phosphate anhydrous (DCPA, CaHPO4), and presents an overview of its properties, processing, and applications in orthopedics. The motivation for the present effort is to highlight the state-of-the-art research and development of monetite and propel the resea...

Background: Copper-containing biomaterials are increasingly applied for bone regeneration due to their pro-angiogenetic, pro-osteogenetic and antimicrobial properties. Therefore, the effect of Cu2+ on osteoclasts, which play a major role in bone remodeling was studied in detail. Methods: Human primary osteoclasts, differentiated from human monoc...

In this study, the hydraulic reactivity and cement formation of baghdadite (Ca3ZrSi2O9) was investigated. The material was synthesized by sintering of a mixture of CaCO3, SiO2 and ZrO2 and then mechanically activated using a planetary mill. This leads to a decrease in particle and crystallite size and a partial amorphization of baghdadite as shown...

The present study aims to extend the material platform for anisotropically structured calcium phosphates to low‐temperature phases such as calcium deficient hydroxyapatite (CDHA) or the secondary phosphates monetite and brushite. This is achieved by the phase‐conversion of highly porous α‐tricalcium phosphate (α‐TCP) scaffolds fabricated by ice‐tem...

This work studies the mechanical and biological properties of Baghdadite (BAG, Ca3ZrSi2O9) coating manufactured on Ti6Al4V substrates by hybrid water-stabilized plasma spray (WSP-H). Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) coating was produced by gas-stabilized atmospheric plasma spray and used as a reference material. Upon spraying, the BAG coating...

Background The role of cement-augmented screw fixation for calcaneal fracture treatment remains unclear. Therefore, this study was performed to biomechanically analyze screw osteosynthesis by reinforcement with either a calcium phosphate (CP)-based or polymethylmethacrylate (PMMA)-based injectable bone cement. Methods A calcaneal fracture (Sanders...

Calcium phosphate cements (CPCs) have been used to treat bone defects and support bone regeneration because of their good biocompatibility and osteointegrative behavior. Since their introduction in the 1980s, remarkable clinical success has been achieved with these biomaterials, because they offer the unique feature of being moldable and even injec...

One of the important challenges in bone tissue engineering is the development of biodegradable bone substitutes with appropriate mechanical and biological properties for the treatment of larger defects and those with complex shapes. Recently, magnesium phosphate (MgP) doped with biologically active ions like strontium (Sr²⁺) have shown to significa...

A major problem concerning the mechanical properties of calcium phosphate cements (CPC) is related to their inherent brittleness, which limits their applicability to non-load bearing bone defects. In this work the preparation of a damage tolerant CPC is presented, where the incorporation of functionalized carbon fibers facilitates steady state flat...

To develop implants with improved bone ingrowth, titanium substrates were coated with homogeneous and dense struvite (MgNH4PO4·6H2O) layers by means of electrochemically assisted deposition. Strontium nitrate was added to the coating electrolyte in various concentrations, in order to fabricate Sr-doped struvite coatings with Sr loading ranging from...

Implants elicit an immunological response after implantation that results in the worst case in a complete implant rejection. This biomaterial-induced inflammation is modulated by macrophages and can be influenced by nanotopographical surface structures such as titania nanotubes or fractal titanium nitride (TiN) surfaces. However, their specific imp...

With more than 50% of bacteria resistant to standard antibiotics, new strategies to treat bacterial infection and colonization are needed. Based on the concept of targeting the bacteria synergistically on various fronts, it is hypothesized that an electrical insult associated with antibacterial materials may be a highly effective means of killing b...

For decades the main focus of titanium implants developed to restore bone functionality was on improved osseointegration. Now additional antimicrobial properties have become desirable due to the risk rising antibiotic resistance pose for implant associated infections. To this end the trace elements copper and zinc were integrated into calcium phosp...

Bone has great self-healing capacity, but above a certain critical size bone defects will not heal spontaneously, requiring intervention to achieve full healing. Amongst the synthetic calcium phosphate (CaP) bone replacement materials, brushite (CaHPO4·2H2O)-based materials are of particular interest, because of their degree of solubility and the r...

Multi-material 3D printing technologies that resolve features at different lengths down to the microscale open new avenues for regenerative medicine, particularly in the engineering of tissue interfaces. Herein, extrusion printing of a bone-biomimetic ceramic ink and melt electrowriting (MEW) of spatially organized polymeric microfibres are integra...

Creating transplantable vascular networks (angiosomes) that are fed and drained by vessels large enough to be surgically reconnected is key to harnessing the potential of regenerative medicine and advancing reconstructive surgical techniques. Currently, the only way to create a new angiosome is nontrivial and involves pressurizing a vein graft by i...

Mineral bone cements were actually not developed for their application as bone-bonding agents, but as bone void fillers. In particular, calcium phosphate cements (CPC) are considered to be unsuitable for that application, particularly under moist conditions. Here, we showed the ex vivo ability of different magnesium phosphate cements (MPC) to adher...

Bone graft substitutes in orthopedic applications have to fulfill various demanding requirements. Most calcium phosphate (CaP) bone graft substitutes are highly porous to achieve bone regeneration, but typically lack mechanical stability. This study presents a novel approach, in which a scaffold structure with appropriate properties for bone regene...

In the treatment of bone non-unions, an alternative to bone autografts is the use of bone morphogenetic proteins (BMPs), e.g., BMP–2, BMP–7, with powerful osteoinductive and osteogenic properties. In clinical settings, these osteogenic factors are applied using absorbable collagen sponges for local controlled delivery. Major side effects of this st...

A complete characterization of spongiosa (bone marrow plus trabecular bone) is required to calculate the absorbed dose to active bone marrow. Due to the complex microanatomy, it is necessary to apply non-conventional imaging methods in nuclear medicine. The aim of this study is validating a phantomless quantification method using dual-energy quanti...

Vascular bone grafts (VBG) are the current clinical standard for the regeneration of large segmental bone defects. Associated morbidity and other shortcomings mandate the development of safe, reliable and cost-effective alternatives. Subcutaneous formation of bone has been achieved in scaffolds axially perfused by an arteriovenous loop (AVL) and se...

Baghdadite (Ca3ZrSi2O9) (BAG) is a calcium silicate (CaSi) based ceramic that demonstrates osteostimulatory function, biocompability and chemical stability. This work studies atmospheric plasma sprayed (APS) BAG and APS hydroxyapatite (HAp) coatings by evaluating their phase compositions, chemical properties, coating microstructure and mechanical p...

Magnesium phosphate cements (MPC) have been demonstrated to have a superior bone regeneration capacity due to their good solubility under in vivo conditions. While in the past only aqueous MPC pastes have been applied, the current study describes the fabrication and in vitro/in vivo testing of an oil-based calcium doped magnesium phosphate (CaMgP)...

The development of alternatives to vascular bone grafts, the current clinical standard for the surgical repair of large segmental bone defects still today represents an unmet medical need. The subcutaneous formation of transplantable bone has been successfully achieved in scaffolds axially perfused by an arteriovenous loop (AVL) and seeded with bon...

A calcium deficient hydroxyapatite (CDHA) forming cement with a bimodal grain size distribution, composed of α-TCP and fine grained CDHA at a weight ratio of 9:1, was modified by the addition of sodium phytate (IP6) in variable amounts ranging from 0.25 to 2 wt.%, related to the powder content. The injectability of the cement paste was drastically...

Surface modification techniques can significantly improve the long-term in vivo performance of biomedical implants as well as provide them with certain biological functions. The judgement of the suitability of a certain treatment has to consider various aspects, namely the specific properties of the chosen substrate material, the biological environ...

Brushite cements have been clinically used for irregular bone defect filling applications, and various strategies have been previously reported to modify and improve their physicochemical properties such as strength and injectability. However, strategies to address other limitations of brushite cements such as low radiopacity or acidity without neg...

(1) Background: Bone substitutes are essential in orthopaedic surgery to fill up large bone defects. Thus, the aim of the study was to compare diverse bone fillers biomechanically to each other in a clinical-relevant test set-up and to detect differences in stability and handling for clinical use. (2) Methods: This study combined compressive streng...

Polycaprolactone (PCL) fiber mats with defined pore architecture were shown to provide sufficient support for a premixed calcium phosphate cement (CPC) paste to serve as a flat and flexible composite material for the potential application in 2-dimensional, curved cranial defects. Fiber mats were fabricated by either melt electrospinning writing (ME...

3D powder printing (3DP) enables the fabrication of porous scaffolds with anisotropic aligned pores for bone tissue engineering and for the fabrication of custom made implants for cranio-maxillofacial surgery. By combining 3D printing and self-setting biocement matrices, a low temperature processing chain can be established for a simultaneous spati...

Dual setting cements composed of an in situ forming hydrogel and a reactive mineral phase combine high compressive strength of the cement with sufficient ductility and bending strength of the polymeric network. Previous studies were focused on the modification with non-degradable hydrogels based on 2-hydroxyethyl methacrylate (HEMA). Here, we descr...

Carbon nanotubes and titania, highly corrosion-resistant materials, were successfully assembled into high surface area microparticles (162 m2/g) in one step using low-power ultrasound. The composite microparticles were electrically conductive (> 0.4 S/cm). The microparticles were deposited as an electrical layer (< 2.5 µm) on a stainless-steel mesh...

Causing a large diameter blood vessel to sprout branches and a capillary network on demand to create a new angiosome is key to harnessing to potential of regenerative medicine and advancing reconstructive surgery. Currently this can only be achieved by connecting a vein graft to an artery by microsurgery, the arteriovenous loop technique (AVL). The...

Calcium phosphate cements composed of β-tricalcium phosphate (β-TCP) and phosphoric acid were modified by addition of 5, 10, 12.5, 15 and 20 wt.% phytic acid (IP6) related to the β-TCP content and compared to a reference containing 0.5 M citric acid monohydrate solution as setting regulator. The hydration reaction of these cements was investigated...

With respect to the composition of natural bone, we established a degradable dual setting system of different poly(ethylene glycol) (PEG)-based hydrogels combined with a brushite cement. The idea was to reinforce the inorganic calcium phosphate mineral phase with an organic, polymeric phase to alter the cement's properties towards ductility and ela...

Silk fibroin is commonly used as scaffold material for tissue engineering applications. In combination with a mineralization with different calcium phosphate phases, it can also be applied as material for bone regeneration. Here, we present a study which was performed to produce mineralized silk fibroin scaffolds with controlled macroporosity. In c...

An integral approach toward in situ tissue engineering through scaffolds that mimic tissue with regard to both tissue architecture and biochemical composition is presented. Monolithic osteochondral and meniscus scaffolds are prepared with tissue analog layered biochemical composition and perpendicularly oriented continuous micropores by a newly dev...

Here, the formation of high surface area microscale assemblies of nanocarbon through phosphate and ultrasound cavitation treatment is reported. Despite high conductivity and large surface area, potential health and safety concerns limit the use of nanocarbon and add challenges to handling. Previously, it is shown that phosphate ultrasonic bonding i...

Electrochemically assisted deposition of Ca(OH)2 (Portlandite) coatings on titanium surfaces has been proven as a promising method to provide the substrate with a most desirable combination of significant bacterial growth reduction on one hand and good biocompatibility on the other. Due to the rapid in vivo transformation of Ca(OH)2 to hydroxyapati...