Prosthesis loosening due to lack of osteointegration between an implant and surrounding bone tissue is one of the most common causes of implant failure. Further, bacterial contamination and biofilm formation onto implants represent a serious complication after surgery. The enhancement of osteointegration can be achieved by using bioconductive materials that promote biological responses in the body, stimulating bone growth and thus bonding to tissue. Through the incorporation of antibacterial substances in bioconductive, biodegradable calcium phosphate (CaP) coatings, faster osteointegration and bactericidal properties can be achieved. In this study, Cu-doped CaP supraparticles are spray-dried and suspension-sprayed CaP ceramic coatings with antibacterial properties are prepared using high-velocity suspension flame spraying (HVSFS). The objective was to increase the coatings’ porosity and investigate which Cu-doped supraparticles have the strongest antibacterial properties when introduced into the coating layers. Biocompatibility was tested on human Osteosarcoma cells MG63. A porosity of at least 13% was achieved and the supraparticles could be implemented, enhancing it up to 16%. The results showed that the addition of Cu-doped supraparticles did not significantly reduce the number of viable cells compared to the Cu-free sample, demonstrating good biocompatibility. The antimicrobial activity was assessed against the bacterial strains Escherichia coli and Staphylococcus aureus, with Safe Airborne Antibacterial testing showing a significant reduction in both Gram-positive and Gram-negative strains on the Cu-doped coatings.

Calcium phosphate (CaP) minerals have shown great promise as bone replacement materials due to their similarity to the mineral phase of natural bone. In addition to biocompatibility and osseointegration, the prevention of infection is crucial, especially due to the high concern of antibiotic resistance. In this context, a controlled drug release as well as biodegradation are important features which depend on the porosity of CaP. An increase in porosity can be achieved by using nanoparticles (NPs), which can be processed to supraparticles, combining the properties of nano- and micromaterials. In this study, Cu-doped CaP supraparticles were prepared to improve the bone substitute properties while providing antibacterial effects. In this context, a modified sol–gel process was used for the synthesis of CaP NPs, where a Ca/P molar ratio of 1.10 resulted in the formation of crystalline β-tricalcium phosphate (β-TCP) after calcination at 1000 °C. In the next step, CaP NPs with Cu²⁺ (0.5–15.0 wt%) were processed into supraparticles by a spray drying method. Cu release experiments of the different Cu-doped CaP supraparticles demonstrated a long-term sustained release over 14 days. The antibacterial properties of the supraparticles were determined against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, where complete antibacterial inhibition was achieved using a Cu concentration of 5.0 wt%. In addition, cell viability assays of the different CaP supraparticles with human telomerase-immortalized mesenchymal stromal cells (hMSC-TERT) exhibited high biocompatibility with particle concentrations of 0.01 mg mL⁻¹ over 72 hours.

Implant–associated infections and aseptic loosening of prosthesis due to insufficient secondary stability continue to present a challenging issue in arthroplasty. Potential solutions include bioactive coatings to promote osseointegration. With this in mind, this study aims to investigate and compare thin bioactive and bioresorbable β-tricalcium phosphate (β-TCP) and calcium alka-li orthophosphate (GB14) coatings, both produced via high velocity suspension flame spraying. To achieve an additional antibacterial effect and to prevent infections through aerosolized contamination, Cu-doped β-TCP supraparticles (SP) are incorporated into the coatings. β-TCP and GB14 coatings with 0.5 wt.% Cu-doped β-TCP SP each were investigated. According to ISO EN 10993–14, a degradation test was performed in TRIS-buffer at pH 7.4 over 120 h. Biocompatibility testing was performed on human osteoblasts using live/dead staining on days 1, 3 and 7 to simultaneously visualize viable and non-viable cells, while cytotoxicity was assessed over a 3 d period with the cytotoxicity assay. To evaluate the antibacterial efficacy, safe airborne antibacterial assays using S. aureus and E. coli were performed. Our investigations demonstrate that Cu is released from the coatings over a period of 120 h. The released Cu-amount results in a significant reduction in colony forming units across all coatings, while only negligibly imparing the behavior of the human osteoblasts. Both coatings exhibit high biocompatibility, with cell counts varying depending on the amount of Cu released. Cytotoxicity testing showed no cytotoxic effects for the samples examined.

We studied the impact of two different thawing mechanisms on the microstructure of defrosted cryopreserved 3D tissue models using transmission Mueller microscopy and a statistical analysis of polarimetric images of thin histological sections of defrosted tissue models. The cryopreserved 3D tissue models were thawed by using either a 37 °C water bath or radio-frequency inductive heating with the magnetic nanoparticles embedded into the 3D tissue model during the preparation process. Polarimetric measurements were conducted at 700 nm and the acquired Mueller matrices of the samples were post-processed using the differential decomposition and the statistical analysis of the maps of the azimuth of the optic axis. Our results indicate the sensitivity of polarimetry to the changes in thawed tissue morphology compared to that of reference non-frozen tissue. Thus, Mueller microscopy can be used as a fast complementary technique to the currently accepted gold standard methods for the assessment of the cryopreserved tissue microstructure after thawing.

Calcium phosphate (CaP) minerals have been widely studied as bone substitutes due to their excellent osteoconductivity and biocompatibility. However, their limited biodegradability remains a challenge. Magnesium phosphates (MgPs) are promising alternatives; offering similar properties to CaP while exhibiting enhanced bioresorption due to their higher solubility. To advance the relatively unexplored field of MgP research, this study investigated Cu‐doped MgP supraparticles with enhanced biodegradability as potential bone substitute materials. For this purpose, MgP nanoparticles (NPs) were synthesized using a modified sol–gel process with different parameter variations to tailor the crystal structure and particle size. The NPs were then spray‐dried with Cu ions (5.0 wt%) to produce antibacterial supraparticles whose unique properties were demonstrated in previous studies on CaP supraparticles. Subsequent calcination was used to study the impact of the crystal structure on Cu release experiments over 14 days as well as its efficacy against the gram‐positive bacterium Staphylococcus aureus . In particular, uncalcined, amorphous MgP supraparticles exhibited high Cu release in bi‐distilled water and antibacterial activity when tested as eluates. Interestingly, all MgP particle systems, with or without Cu, achieved a significant bactericidal effect against S. aureus at a particle concentration of 100 mg/mL in Mueller Hinton Broth, thereby demonstrating the antibacterial effect of Mg ²⁺ ions. The cell viability of the supraparticles was also investigated using human telomerase–immortalized mesenchymal stromal cells (hMSC‐TERT), which exhibited high biocompatibility at particle concentrations of 0.01–0.1 mg/L over 72 h. Uncalcined Cu‐doped MgP supraparticles induced the expression of proinflammatory markers (interleukin 1 beta, interleukin 6, interleukin 8, and serum amyloid A1), whereas the expression of osteogenic markers (alkaline phosphatase, bone gamma‐carboxyglutamate protein, and secreted phosphoprotein 1) was only slightly affected. However, the osteogenic differentiation of hMSC‐TERT showed a positive effect on mineralization when exposed to uncalcined MgP supraparticles. Overall, the results indicate that MgP supraparticles, both with and without Cu, exhibit high biocompatibility and hold promise for applications in bone tissue regeneration.

The present study investigates the effect of thin porous ceramic coatings on implant stability, focusing on two materials: a calcium alkali orthophosphate (GB14, Ca ₂ KNa(PO ₄ ) ₂ ) and β-tricalcium phosphate (β-TCP), with and without copper (Cu) incorporation. The coatings were applied to titanium implant surfaces (CP Ti, grade 2) and characterized for porosity and microstructure. The in vivo performance of the material is assessed in a New Zealand White rabbit model. Following defined healing periods, biomechanical push-out testing were performed. The results of β-TCP/Cu for cancellous bone show that Cu-doped coatings exhibit significantly improved bone integration compared to their Cu-free counterparts. The enhanced fixation is attributed to the bioactive and potential antibacterial properties of copper, which may stimulate osteogenesis and the presence of supraparticles in the Cu samples. Furthermore, the incorporation of β -TCP supraparticles into the ceramic matrix increases overall coating porosity, facilitating deeper bone ingrowth and improved mechanical interlocking. This structural change results in improved osseointegration compared to less porous coatings. This structural change results in improved osseointegration compared to less porous coatings. The results of this study demonstrate that combining copper incorporation with enhanced porosity through supraparticles can improve implant stability by shortening the time required for the transition from primary to secondary stability. This approach offers a promising strategy for optimizing surface design in orthopedic and dental implants.