Comparative analysis of protocols for decellularization of corneal lenticular tissue

Shortage of donor corneas is a burning issue in ophthalmology. That is why there is a search for new alternative ways for treating corneal diseases. Decellularization technologies make it possible to create corneal tissue-engineered constructs that can adrress the issue of donor corneal shortage. Objective: to conduct a comparative analysis of effective methods for treating the corneal lenticula and to create an optimized and standardized decellularization protocol. Materials and methods. Corneal stromal lenticules obtained after ReLEx SMILE surgery were chosen for the study. Lenticule parameters: thickness 77–120 microns, diameter 6.5 mm. We used 3 protocols for the treatment of lenticules: 1) treatment with 1.5 M sodium chloride with nucleases (NaCl); 2) 0.1% SDS (SDS); 3) treatment with Trypsin-EDTA solution, followed by double washing in a hypotonic Tris buffer solution with nucleases (Trypsin-EDTA). Optical properties of lenticles were determined spectrophotometrically, where the samples before decellularization served as a control. Fluorescence imaging of nuclear material in the original cryosections was performed using Hoechst dye. The state of collagen fiber ultrastructure was assessed by scanning electron microscopy. The quantitative DNA content in fresh lenticules and in lenticules after treatment was analyzed. Results. All three decellularization protocols effectively removed nuclear and cellular material; the residual DNA content was < 50 ng/mg. However, the Trypsin-EDTA protocol led to significant damage to the extracellular matrix structure, which negatively affected the transparency of corneal tissue-engineered constructs. Transparency of samples for the NaCl protocol was close to native lenticules. Conclusion. To create a corneal tissue-engineered construct, NaCl decellularization protocols appear to be optimized and can be used to treat various corneal diseases.

A rapidly-dissolving silica-silver bioactive glass for cariostatic applications

In this study, bioactive glasses were designed for the purposes of reducing the incidence of dental caries and lesion formation by supplying the teeth with therapeutic ions which may support remineralization and provide an antibacterial effect against oral cavity bacteria. Three glasses were synthesised through the melt quench method: Si-Control (SiO2-CaO-P2O5-Na2O), Si-02 and Si-05, where 0.2% and 0.5% Ag2O were substituted, respectively, for SiO2 in the control glass. The glasses were then ground, characterized and dissolved in tris buffer solution (pH=7.30) for 6, 12 and 24 hours, with the pH rise of the solution being recorded (7.48 for Si-Control, and 7.66 for both Si-02 and Si-05 after 24 hours) and the ions that were released into the tris buffer solution quantified. Samples of each glass were subsequently embedded into non-fluoridated toothpaste and samples of the paste were used to brush resin-mounted lamb molars after a 1.0M HCl overnight demineralization challenge. Knoop microhardness measurements were recorded before and after brushing to determine the presence of remineralization on the surface of the teeth (Percent Surface Hardness Loss of 37%, 35% and 34% for Si-Control, Si-02 and Si-05 respectively after 24 hours). Four oral cavity bacterial strains were isolated through swabs of the inner cheek, gums and teeth surfaces of three volunteers, and placed on agar discs. 0.5g of each glass were placed onto the discs and the resultant inhibition zones were measured after 6, 12 and 24 hours. Si-05 consistently performed better than Si-02 on all strains and timeframes, while Si-Control exhibited no antibacterial effect at any time point.

A rapidly-dissolving silica-silver bioactive glass for cariostatic applications

In this study, bioactive glasses were designed for the purposes of reducing the incidence of dental caries and lesion formation by supplying the teeth with therapeutic ions which may support remineralization and provide an antibacterial effect against oral cavity bacteria. Three glasses were synthesised through the melt quench method: Si-Control (SiO2-CaO-P2O5-Na2O), Si-02 and Si-05, where 0.2% and 0.5% Ag2O were substituted, respectively, for SiO2 in the control glass. The glasses were then ground, characterized and dissolved in tris buffer solution (pH=7.30) for 6, 12 and 24 hours, with the pH rise of the solution being recorded (7.48 for Si-Control, and 7.66 for both Si-02 and Si-05 after 24 hours) and the ions that were released into the tris buffer solution quantified. Samples of each glass were subsequently embedded into non-fluoridated toothpaste and samples of the paste were used to brush resin-mounted lamb molars after a 1.0M HCl overnight demineralization challenge. Knoop microhardness measurements were recorded before and after brushing to determine the presence of remineralization on the surface of the teeth (Percent Surface Hardness Loss of 37%, 35% and 34% for Si-Control, Si-02 and Si-05 respectively after 24 hours). Four oral cavity bacterial strains were isolated through swabs of the inner cheek, gums and teeth surfaces of three volunteers, and placed on agar discs. 0.5g of each glass were placed onto the discs and the resultant inhibition zones were measured after 6, 12 and 24 hours. Si-05 consistently performed better than Si-02 on all strains and timeframes, while Si-Control exhibited no antibacterial effect at any time point.

Impact of Glass Composition on Hydrolytic Degradation of Polylactide/Bioactive Glass Composites

Understanding the degradation of a composite material is crucial for tailoring its properties based on the foreseen application. In this study, poly-L,DL-lactide 70/30 (PLA70) was compounded with silicate or phosphate bioactive glass (Si-BaG and P-BaG, respectively). The composite processing was carried out without excessive thermal degradation of the polymer and resulted in porous composites with lower mechanical properties than PLA70. The loss in mechanical properties was associated with glass content rather than the glass composition. The degradation of the composites was studied for 40 weeks in Tris buffer solution Adding Si-BaG to PLA70 accelerated the polymer degradation in vitro more than adding P-BaG, despite the higher reactivity of the P-BaG. All the composites exhibited a decrease in mechanical properties and increased hydrophilicity during hydrolysis compared to the PLA70. Both glasses dissolved through the polymer matrix with a linear, predictable release rate of ions. Most of the P-BaG had dissolved before 20 weeks in vitro, while there was still Si-BaG left after 40 weeks. This study introduces new polymer/bioactive glass composites with tailorable mechanical properties and ion release for bone regeneration and fixation applications.

Calcium Carbonate in Bio-Based Material and Factor Affecting Its Precipitation Rate for Repairing Concrete

The use of bio-based material for repairing concrete is a relatively new method. Therefore, more results from simulated real-condition experiments are needed before being applied on a practical scale. In the recent past, several studies have been conducted on the improvement of bio-based repair materials. In this study, the bio-based material involving yeast, glucose, and calcium acetate mixed in a Tris buffer solution showed the potential to develop a microbial process leading to the precipitation of calcium carbonate. We investigated the factors affecting the precipitation rate of the calcium carbonate of bio-based materials for repairing leakage in the concrete specimens. Based on a series of experiments involving temperature, the type of dry yeast, and the concentration of the Tris buffer solution, the composition of bio-based materials with the highest precipitation rate of calcium carbonate was selected. The selected mixture could be applied to repair leakage of concrete until the cracks are sealed entirely.

Preparation of Calcium Phosphate Glasses Containing Nb2O5 and TiO2

60CaO-30P2O5-(10 ̶ x)Nb2O5-xTiO2 (x = 0 ~ 10, mol%) glasses were prepared in order to obtain biomaterials with high chemical durability and therapeutic ions releasability. Dissolution test of these glasses using Tris buffer solution showed the controlled release of niobate ions from Nb2O5-containing glasses and the formation of calcium titanate in some of them. These behavior might induce positive effects for bone regeneration.

Phosphotungstic Acid, Silicotungstic Acid and Silicon Tungsten-Cobalt Heteropoly Acid with Bovine Serum Albumin Interaction

The interactions of bovine serum albumin (BSA) with phosphotungstic heteropoly acid (PW), silicon tungsten heteropoly acid (SiW) and silicon tungsten-cobalt acid (SiWCo) were studied by fluorescence spectroscopy and UV absorption spectroscopy at Tris buffer solution (pH = 7.40). It was found that the fluorescence quenching of PW, SiW and SiWCo with BSA was static and the binding constant, binding site and the thermodynamic parameters were calculated at 298 and 310K. In addition, the conformations of BSA impacted by PW, SiW and SiWCo were researched using synchronous fluorescence. The results showed that PW, SiW and SiWCo all could interact with BSA but they had not changed the conformation of BSA.