1D ZnO-Au nanocomposites as label-free photoluminescence immunosensors for rapid detection of Listeria monocytogenes

In this study, we explore the potential of 1D ZnO-Au nanocomposites as innovative label-free photoluminescence (PL) immunosensors for rapidly detecting Listeria monocytogenes, a significant concern in food safety. We synthesized ZnO nanorods (ZnO_NR) and nanowires (ZnO_NW), followed by Au deposition to create ZnO_NR/Au and ZnO_NW/Au nanocomposites. Our analyses, including SEM, TEM, Raman spectroscopy, and photoluminescence (PL), revealed distinct structural and optical properties of these nanocomposites, especially noting the superior crystallinity and stability of ZnO_NR/Au. The biosensor performance was evaluated through PL sensitivity to Anti-Listeria antibodies, demonstrating that ZnO_NR with higher concentration of Au nanoparticles exhibited higher sensitivity and a lower limit of detection (LOD), attributed to a greater density of Listeria binding sites. The developed biosensor demonstrated a remarkable limit of detection (LOD) of 8.3 × 102 CFU/mL, rivaling or surpassing conventional culture-based methods and some molecular techniques. This research underscores the critical role of Au deposition duration in optimizing biosensor performance and presents a promising advancement in rapid and sensitive Listeria detection, with significant implications for enhancing food safety protocols.

Synthetic Calcium-Phosphate Materials for Bone Grafting

Synthetic bone grafting materials play a significant role in various medical applications involving bone regeneration and repair. Their ability to mimic the properties of natural bone and promote the healing process has contributed to their growing relevance. While calcium-phosphates and their composites with various polymers and biopolymers are widely used in clinical and experimental research, the diverse range of available polymer-based materials poses challenges in selecting the most suitable grafts for successful bone repair. This review aims to address the fundamental issues of bone biology and regeneration while providing a clear perspective on the principles guiding the development of synthetic materials. In this study, we delve into the basic principles underlying the creation of synthetic bone composites and explore the mechanisms of formation for biologically important complexes and structures associated with the various constituent parts of these materials. Additionally, we offer comprehensive information on the application of biologically active substances to enhance the properties and bioactivity of synthetic bone grafting materials. By presenting these insights, our review enables a deeper understanding of the regeneration processes facilitated by the application of synthetic bone composites.

From Synthesis to Clinical Trial: Novel Bioinductive Calcium Deficient HA/β-TCP Bone Grafting Nanomaterial

Maxillary sinus augmentation is a commonly used procedure for the placement of dental implants. However, the use of natural and synthetic materials in this procedure has resulted in postoperative complications ranging from 12% to 38%. To address this issue, we developed a novel calcium deficient HA/β-TCP bone grafting nanomaterial using a two-step synthesis method with appropriate structural and chemical parameters for sinus lifting applications. We demonstrated that our nanomaterial exhibits high biocompatibility, enhances cell proliferation, and stimulates collagen expression. Furthermore, the degradation of β-TCP in our nanomaterial promotes blood clot formation, which supports cell aggregation and new bone growth. In a clinical trial involving eight cases, we observed the formation of compact bone tissue 8 months after the operation, allowing for the successful installation of dental implants without any early postoperative complications. Our results suggest that our novel bone grafting nanomaterial has the potential to improve the success rate of maxillary sinus augmentation procedures.

BIOLOGICAL BEHAVIOUR OF CHITOSAN ELECTROSPUN NANOFIBROUS MEMBRANES AFTER DIFFERENT NEUTRALISATION METHODS

Chitosan electrospun nanofibres were synthesised in two different trifluoroacetic acid (TFA)/dichloromethane (DCM) solvent ratios and then neutralised in aqueous and ethanol sodium-based solutions (NaOH and Na2CO3) to produce insoluble materials with enhanced biological properties for regenerative and tissue engineering applications. Structural, electronic, and optical properties and the swelling capacity of the prepared nanofibre membrane were studied by scanning electron microscopy, Fourier-transform infrared spectroscopy, and photoluminescence. Cell viability (with the U2OS cell line) and antibacterial properties (against Staphylococcus aureus and Escherichia coli) assays were used to assess the biomedical potential of the neutralised chitosan nanofibrous membranes. A 7:3 TFA/DCM ratio allows for an elaborate nanofibrous membrane with a more uniform fibre size distribution. Neutralisation in aqueous NaOH only maintains a partial fibrous structure. At the same time, neutralisation in NaOH ethanol-water maintains the structure during 1 month of degradation in phosphate-buffered saline and distilled water. All membranes demonstrate high biocompatibility, but neutralisation in ethanol solutions affects cell proliferation on materials made with 9:1 TFA/DCM. The prepared nanofibrous mats could constrain the growth of both gram-positive and gram-negative microorganisms, but 7:3 TFA/DCM membranes inhibited bacterial growth more efficiently. Based on structural, degradation, and biological properties, 7:3 TFA/DCM chitosan nanofibrous membranes neutralised by 70% ethanol/30% aqueous NaOH exhibit potential for biomedical and tissue engineering applications.

Impact of Electrospinning Parameters and Post-Treatment Method on Antibacterial and Antibiofilm Activity of Chitosan Nanofibers

Chitosan, a natural biopolymer, is an ideal candidate to prepare biomaterials capable of preventing microbial infections due to its antibacterial properties. Electrospinning is a versatile method ideally suited to process biopolymers with minimal impact on their physicochemical properties. However, fabrication parameters and post-processing routine can affect biological activity and, therefore, must be well adjusted. In this study, nanofibrous membranes were prepared using trifluoroacetic acid and dichloromethane and evaluated for physiochemical and antimicrobial properties. The use of such biomaterials as potential antibacterial agents was extensively studied in vitro using Staphylococcus aureus and Escherichia coli as test organisms. The antibacterial assay showed inhibition of bacterial growth and eradication of the planktonic cells of both E. coli and S. aureus in the liquid medium for up to 6 hrs. The quantitative assay showed a significant reduction in bacteria cell viability by nanofibers depending on the method of fabrication. The antibacterial properties of these biomaterials can be attributed to the structural modifications provided by co-solvent formulation and application of post-treatment procedure. Consequently, the proposed antimicrobial surface modification method is a promising technique to prepare biomaterials designed to induce antimicrobial resistance via antiadhesive capability and the biocide-releasing mechanism.

Hemostatic and Tissue Regeneration Performance of Novel Electrospun Chitosan-Based Materials

The application of chitosan (Ch) as a promising biopolymer with hemostatic properties and high biocompatibility is limited due to its prolonged degradation time, which, in turn, slows the repair process. In the present research, we aimed to develop new technologies to reduce the biodegradation time of Ch-based materials for hemostatic application. This study was undertaken to assess the biocompatibility and hemostatic and tissue-regeneration performance of Ch-PEO-copolymer prepared by electrospinning technique. Chitosan electrospinning membranes (ChEsM) were made from Ch and polyethylene oxide (PEO) powders for rich high-porous material with sufficient hemostatic parameters. The structure, porosity, density, antibacterial properties, in vitro degradation and biocompatibility of ChEsM were evaluated and compared to the conventional Ch sponge (ChSp). In addition, the hemostatic and bioactive performance of both materials were examined in vivo, using the liver-bleeding model in rats. A penetrating punch biopsy of the left liver lobe was performed to simulate bleeding from a non-compressible irregular wound. Appropriately shaped ChSp or ChEsM were applied to tissue lesions. Electrospinning allows us to produce high-porous membranes with relevant ChSp degradation and swelling properties. Both materials demonstrated high biocompatibility and hemostatic effectiveness in vitro. However, the antibacterial properties of ChEsM were not as good when compared to the ChSp. In vivo studies confirmed superior ChEsM biocompatibility and sufficient hemostatic performance, with tight interplay with host cells and tissues. The in vivo model showed a higher biodegradation rate of ChEsM and advanced liver repair.

Hemostatic performance and biocompatibility of chitosan-based agents in experimental parenchymal bleeding

The uncontrolled parenchymatic bleeding is still a cause of serious complications in surgery and require new effective hemostatic materials. In recent years, numerous chitosan-based materials have been intensively studied for parenchymatic bleeding control but still require to increased safety and effectiveness. The current research is devoted to new hemostatic materials made of natural polymer (chitosan) developed using electrospinning and microwave-assisted methods. Hemostatic performance, biocompatibility, degradation, and in-vivo effectiveness were studied to assess functional properties of new materials. Chitosan-based agents demonstrated considerable hemostatic performance, moderate biodegradation pace and high biocompatibility in vitro. Using the electrospinning-made chitosan-copolymer significantly improved in vivo biocompatibility and degradation of Chitosan-based agents that provides opportunities for its implementation for visceral bleeding management. Chitosan aerogel could be effectively applied in hemostatic patch development due to high antibacterial activity but it is not recommended for visceral application due to moderate inflammatory effect and slow degradation.

Formation of Solution-derived Hydroxyapatite Coatings on Titanium Alloy in the Presence of Magnetron-sputtered Alumina Bond Coats

Hydroxyapatite Ca₁₀(PO₄)₆₍OH)₂ (HAp) and calcium phosphate ceramic materials and coatings are widely used in medicine and dentistry because of their ability to enhance the tissue response to implant surfaces and promote bone ingrowth and osseoconduction processes. The deposition conditions have a great influence on the structure and biofunctionality of calcium phosphate coatings. Corrosion processes and poor adhesion to substrate material reduce the lifetime of implants with calcium phosphate coatings. The research has focused on the development of advanced methods to deposit double-layered ceramic oxide/calcium phosphate coatings by a hybrid technique of magnetron sputtering and thermal methods. The thermal method can promote the crystallization and the formation of HAp coatings on titanium alloy Ti6Al4V substrates at low temperature, based on the principle that the solubility of HAp in aqueous solutions decreases with increasing substrate temperature. By this method, hydroxyapatite directly coated the substrate without precipitation in the initial solution. Using a thermal substrate method, calcium phosphate coatings were prepared at substrate temperatures of 100-105 ^oC. The coated metallic implant surfaces with ceramic bond coats and calcium phosphate layers combine the excellent mechanical properties of metals with the chemical stability of ceramic materials. The corrosion test results show that the ceramic oxide (alumina) coatings and the double-layered alumina-calcium phosphate coatings improve the corrosion resistance compared with uncoated Ti6Al4V and single-layered Ti6Al4V/calcium phosphate substrates. In addition, the double-layered alumina/hydroxyapatite coatings demonstrate the best biocompatibility during in vitro tests.