Ana Isabel Moreno Florez

Ceramic filters are an effective, low-cost solution for water potabilization, particularly in rural communities. The integration of 3D printing has advanced this traditional approach by enabling precise control over design parameters that govern filtration efficiency. Gyroid-type ceramic scaffolds for water treatment were fabricated by clay-based extrusion 3D printing. Two ceramic pastes (ECP 1 and ECP 2) containing kaolin, attapulgite, alumina, and feldspar were formulated; ECP 2 incorporated 10 wt% activated carbon as a sacrificial porogenic phase. Rheological characterization using rotational rheometry and Bingham model fitting identified 40 wt% water as optimal for extrusion. Sintering at 1100°C produced interconnected open-pore networks in ECP 2 (apparent porosity: 23.6%; water absorption: 11.8%). Scaffolds were functionalized with silver nanoparticles (AgNPs) and ethanolic extracts of Moringa oleifera . AgNPs exhibited surface plasmon resonance at 422 nm; silver leaching was 0.00282 ppm (WHO limit: 0.1 ppm). Ethanolic extract E2 (80% v/v) showed significantly lower MIC (0.175 g/mL) than E1 (0.35 g/mL; p < 0.05) and bactericidal activity (MBC/MIC ⩽ 4.0). Functionalized scaffolds (EG) reduced biofilm formation by 80%–95% versus controls at 24 h (MTT assay) and maintained cellular compatibility above the 80% ISO 10993-5 threshold at 7 days. This combination of properties positions them as a highly promising alternative for advanced ceramic water filters.

Oral diseases such as dental caries, stomatitis, and periodontitis are closely associated with biofilms that are resistant to conventional therapeutic approaches. Streptococcus sanguinis and Streptococcus mutans play a key role as primary and secondary colonizers of oral surfaces, respectively, and interact synergistically with other species, including Candida albicans, to promote the establishment and progression of infection. Objective: To evaluate the antimicrobial activity of ethanolic extracts of propolis from Tame (Arauca) on biofilms formed in co-cultures from reference strains and co-cultures with clinical isolates of oral pathogens. Methodology: Propolis was collected from Apis mellifera hives placed in rural Tame (Arauca), located in the foothills of the Eastern Andes (Colombia). Ethanolic extracts of propolis (EEP) were prepared in a 0.07 g/mL concentration and biological characterization was performed on single and complex co-cultures of S. mutans (serotype c), S. sanguinis, and C. albicans using disc diffusion test, determination of MIC and BMC, growth curves and biofilm formation. The cell viability and metabolic activity of primary cell cultures derived from a dental pulp explant were evaluated using the MTT assay. Results: EEP exhibited higher inhibition zones than chlorhexidine against S. mutans and C. albicans and lower efficacy against S. sanguinis. Among the microorganisms evaluated, S. mutans showed the lowest MIC and BCM values, followed by C. albicans and S. sanguinis. Growth curves and biofilm formation assays revealed higher inhibition in co-cultures of reference strains (S. mutans + C. albicans), while multi-species cultures (S. mutans + S. sanguinis + C. albicans), or clinical strains (S. mutans clinical isolated + S. sanguinis + C. albicans), showed higher resistance. Cell viability assays revealed low cytotoxicity (<30%) in primary cell cultures. Conclusions: EEPs exhibited antimicrobial activity against relevant oral pathogens, especially in simple co-cultures, supporting their potential as natural therapeutic alternatives. However, their efficacy decreases in the presence of clinical strains and complex co-cultures, highlighting the importance of considering these variables in the development of oral treatments.

Silver-doped calcium phosphate powders were synthesized by solution combustion synthesis. X-ray powder diffraction confirmed the phase composition, demonstrating the influence of silver on the formation of hydroxyapatite (HAP) and tricalcium phosphate (β-TCP). Specifically, increasing silver concentration led to a decrease in HAP and an increase in the β-TCP phase. Rietveld refinement analysis revealed a corresponding increase in β-TCP crystallite size (from 62 to 98 nm) with higher silver concentrations, suggesting the incorporation of silver into the β-TCP lattice. Silver phosphate was observed only at an Ag/(Ag + Ca) cationic ratio of 0.12. Scanning electron microscopy (SEM) revealed aggregates formed during combustion, while transmission electron microscopy (TEM) showed Ag nanoparticles supported on the calcium phosphate. Antimicrobial assays demonstrated activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria for the powders with Ag/(Ag + Ca) ratios of 0.12 and 0.09. Additionally, potential photocatalytic activity was assessed via methylene blue (MB) degradation under sunlight. UV-Vis spectroscopy revealed significant MB degradation after 4 h of sunlight exposure, with the blue solution becoming transparent. These results indicate that the synthesized powders are promising for use in antimicrobial and photocatalytic applications.

Ceramic stereolithography scaffolds with designs based on triple periodic minimal surfaces (TPMS) were developed for potential applications in bone tissue regeneration. An acrylic-based resin with calcium phosphate nanoparticles were used. Particles were synthesized via Combustion in solution, resulting in hydroxyapatite and β-TCP phases. Suspensions with 35, 40, and 50 vol% particles, using a 10 wt% of dispersant, were prepared and rheologically characterized to ensure suitable viscosities for printing, and were used to print gyroid scaffolds by DLP technique. The suspension with the highest ceramic load demonstrated the highest viscosity. The green bodies were morphologically and mechanically characterized before and after sintering. Volumetric shrinkage, morphological characteristics by digital and FE-SEM images, and compressive strength were evaluated. Polymeric-ceramic (Hybrid) scaffolds before sintering exhibited better compressive strength than sintered ones. Ceramic scaffolds achieved compressive strength values up to 0.9 MPa, comparable to those of cancellous and cortical bone. The optimal scaffolds (50CPF) were subjected to degradation tests in PBS and were impregnated with ethanolic extract of propolis from Arauca, Colombia, for biological analysis using the L929 cell line. The results indicate that ceramic stereolithography is an effective technique to produce scaffolds with optimal characteristics for potential applications in bone tissue regeneration. Graphical Abstract

Context: The development of porous devices using materials modified with various natural agents has become a priority for bone healing processes in the oral and maxillofacial field. There must be a balance between the proliferation of eukaryotic and the inhibition of prokaryotic cells to achieve proper bone health. Infections might inhibit the formation of new alveolar bone during bone graft augmentation.Objective: This study aimed to evaluate the in vitro osteogenic behavior of human bone marrow stem cells and assess the antimicrobial response to 3D-printed porous scaffolds using propolis-modified wollastonite.Methodology: A fractional factorial design of experiments was used to obtain a 3D printing paste for developing scaffolds with a triply periodic minimal surface (TPMS) gyroid geometry based on wollastonite and modified with an ethanolic propolis extract. The antioxidant activity of the extracts was characterized using free radical scavenging methods (DPPH and ABTS). Cell proliferation and osteogenic potential using Human Bone Marrow Stem Cells (bmMSCs) were assessed at different culture time points up to 28 days. MIC and inhibition zones were studied from single strain cultures, and biofilm formation was evaluated on the scaffolds under co-culture conditions. The mechanical strength of the scaffolds was evaluated.Results: Through statistical design of experiments, a paste suitable for printing scaffolds with the desired geometry was obtained. Propolis extracts modifying the TPMS gyroid scaffolds showed favorable cell proliferation and metabolic activity with osteogenic potential after 21 days. Additionally, propolis exhibited antioxidant activity, which may be related to the antimicrobial effectiveness of the scaffolds against S. aureus and S. epidermidis cultures. The mechanical properties of the scaffolds were not affected by propolis impregnation.Conclusion: These results demonstrate that propolis-impregnated porous wollastonite scaffolds might have the potential to stimulate bone repair in maxillofacial tissue engineering applications.

Several diseases and injuries cause irreversible damage to bone tissues, which may require partial or total regeneration or replacement. Tissue engineering suggests developing substitutes that may contribute to the repair or regeneration process by using three-dimensional lattices (scaffolds) to create functional bone tissues. Herein, scaffolds comprising polylactic acid and wollastonite particles enriched with propolis extracts from the Arauca region of Colombia were developed as gyroid triply periodic minimal surfaces using fused deposition modeling. The propolis extracts exhibited antibacterial activity against Staphylococcus aureus (ATCC 25175) and Staphylococcus epidermidis (ATCC 12228), which cause osteomyelitis. The scaffolds were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, contact angle, swelling, and degradation. Their mechanical properties were assessed using static and dynamic tests. Cell viability/proliferation assay was conducted using hDP-MSC cultures, while their bactericidal properties against monospecies cultures (S. aureus and S. epidermidis) and cocultures were evaluated. The wollastonite particles did not affect the physical, mechanical, or thermal properties of the scaffolds. The contact angle results showed that there were no substantial differences in the hydrophobicity between scaffolds with and without particles. Scaffolds containing wollastonite particles suffered less degradation than those produced using PLA alone. A representative result of the cyclic tests at F_max = 450 N showed that the maximum strain reached after 8000 cycles is well below the yield strain (i.e., S. aureus and S. epidermidis and their cocultures. The samples without propolis loads did not show inhibition halos, whereas those loaded with EEP exhibited halos of 17.42 ± 0.2 mm against S. aureus and 12.9 ± 0.5 mm against S. epidermidis. These results made the scaffolds possible bone substitutes that exert control over species with a proliferative capacity for the biofilm-formation processes required for typical severe infectious processes.