Release Of Tetracycline Research Articles

Immunomodulatory microneedle patch for periodontal tissue regeneration

Periodontal diseases are caused by microbial infection and the recruitment of destructive immune cells. Current therapies mainly deal with bacteria elimination, but the regeneration of periodontal tissues remains a challenge. Here we developed a modular microneedle (MN) patch that delivered both antibiotic and cytokines into the local gingival tissue to achieve immunomodulation and tissue regeneration. This MN patch included a quickly dissolvable gelatin membrane for an immediate release of tetracycline and biodegradable GelMA MNs that contained tetracycline-loaded poly(lactic-co-glycolic acid) nanoparticles and cytokine-loaded silica microparticles for a sustained release. Antibiotic release completely inhibited bacteria growth, and the release of IL-4 and TGF-β induced the repolarization of anti-inflammatory macrophages and the formation of regulatory T cells in vitro. In vivo delivery of MN patch into periodontal tissues suppressed proinflammatory factors and promoted pro-regenerative signals and tissue healing, which demonstrated the therapeutic potential of local immunomodulation for tissue regeneration.

Introducing a flexible drug delivery system based on poly(glycerol sebacate)-urethane and its nanocomposite: potential application in the prevention and treatment of oral diseases

In this study, a novel biopolymer based on poly(glycerol sebacic)-urethane (PGS-U) and its nanocomposites containing Cloisite@30B were synthesized by facile approach in which the crosslinking was created by aliphatic hexamethylene diisocyanate (HDI) at room temperature and 80 °C. Moreover, metronidazole and tetracycline drugs were selected as target drugs and loaded into PGSU based nanocomposites. A uniform and continuous microstructure with smooth surface is observed in the case of pristine PGS-U sample. The continuity of microstructure is observed in the case of all bionanocomposites. XRD result confirmed an intercalated morphology for PGSU containing 5 wt% of clay nanoparticles with a d-spacing 3.4 nm. The increment of nanoclay content up to 5%, the ultimate tensile stress and elastic modulus were obtained nearly 0.32 and 0.83 MPa, which the latter was more than eight-fold than that of pristine PGS-U. A sustained release for both dugs was observed by 200 h. The slowest and controlled drug release rate was determined in the case of PGSU containing 5 wt% clay and cured at 80 °C. A non-Fickian diffusion can be concluded in the case of tetracycline release via PGS-U/nanoclay bionanocomposites, while a Fickian process was detected in the case of metronidazole release by PGS-U/nanoclay bionanocomposites. As a result, the designed scaffold showed high flexibility, which makes it an appropriate option for utilization in the treatment of periodontal disease.

Composite Drug Delivery System Based on Amorphous Calcium Phosphate-Chitosan: An Efficient Antimicrobial Platform for Extended Release of Tetracycline.

One major warning emerging during the first worldwide combat against healthcare-associated infections concerns the key role of the surface in the storage and transfer of the virus. Our study is based on the laser coating of surfaces with an inorganic/organic composite mixture of amorphous calcium phosphate–chitosan–tetracycline that is able to fight against infectious agents, but also capable of preserving its activity for a prolonged time, up to several days. The extended release in simulated fluids of the composite mixture containing the drug (tetracycline) was demonstrated by mass loss and UV–VIS investigations. The drug release profile from our composite coatings proceeds via two stages: an initial burst release (during the first hours), followed by a slower evolution active for the next 72 h, and probably more. Optimized coatings strongly inhibit the growth of tested bacteria (Enterococcus faecalis and Escherichia coli), while the drug incorporation has no impact on the in vitro composite’s cytotoxicity, the coatings proving an excellent biocompatibility sustaining the normal development of MG63 bone-like cells. One may, therefore, consider that the proposed coatings’ composition can open the prospective of a new generation of antimicrobial coatings for implants, but also for nosocomial and other large area contamination prevention.

Binding of Tetracyclines to Acinetobacter baumannii TetR Involves Two Arginines as Specificity Determinants.

Acinetobacter baumannii is an important nosocomial pathogen that requires thoughtful consideration in the antibiotic prescription strategy due to its multidrug resistant phenotype. Tetracycline antibiotics have recently been re-administered as part of the combination antimicrobial regimens to treat infections caused by A. baumannii. We show that the TetA(G) efflux pump of A. baumannii AYE confers resistance to a variety of tetracyclines including the clinically important antibiotics doxycycline and minocycline, but not to tigecycline. Expression of tetA(G) gene is regulated by the TetR repressor of A. baumannii AYE (AbTetR). Thermal shift binding experiments revealed that AbTetR preferentially binds tetracyclines which carry a O-5H moiety in ring B, whereas tetracyclines with a 7-dimethylamino moiety in ring D are less well-recognized by AbTetR. Confoundingly, tigecycline binds to AbTetR even though it is not transported by TetA(G) efflux pump. Structural analysis of the minocycline-bound AbTetR-Gln116Ala variant suggested that the non-conserved Arg135 interacts with the ring D of minocycline by cation-π interaction, while the invariant Arg104 engages in H-bonding with the O-11H of minocycline. Interestingly, the Arg135Ala variant exhibited a binding preference for tetracyclines with an unmodified ring D. In contrast, the Arg104Ala variant preferred to bind tetracyclines which carry a O-6H moiety in ring C except for tigecycline. We propose that Arg104 and Arg135, which are embedded at the entrance of the AbTetR binding pocket, play important roles in the recognition of tetracyclines, and act as a barrier to prevent the release of tetracycline from its binding pocket upon AbTetR activation. The binding data and crystal structures obtained in this study might provide further insight for the development of new tetracycline antibiotics to evade the specific efflux resistance mechanism deployed by A. baumannii.

Three-Dimensional Printed Design of Antibiotic-Releasing Esophageal Patches for Antimicrobial Activity Prevention.

Pharyngoesophageal defects can cause exposure to various bacterial flora and severe inflammation. We fabricated a biodegradable polycaprolactone (PCL) patch composed of both thin film and three-dimensional (3D) printed lattice, and then investigated the efficacy of pharyngoesophageal reconstruction by using 3D printed antibiotic-releasing PCL patches that inhibited early inflammation by sustained tetracycline (TCN) release from both thin PCL films and printed rods implanted in esophageal partial defects. PCL was 3D printed in lattice form on a presolution casted PCL thin film at ∼100 μm resolution. TCN was loaded onto the PCL-printed patches by 3D printing a mixture of TCN and PCL particles melted at 100°C. TCN exhibited sustained release in vitro for over 1 month. After loading TCN, the patches showed decreased tensile strength and Young's modulus, and less than 20% TCN was slowly released from the 2.5% TCN-loaded PCL patches over 150 days. Cytotoxicity tests of extract solutions from patch samples demonstrated excellent in vitro cell compatibility. Antibiotic-releasing PCL patches were then transplanted into partial esophageal defects in rats. Microcomputed tomography analysis revealed no leak of orally injected contrast agent in the entire esophagus. Tissue remodeling was examined through histological responses of M1 and M2 macrophages. In particular, the 1% and 3% TCN patch groups exhibited significant muscle layer regeneration by desmin immunostaining. Further histological and immunofluorescence analyses revealed that the 1% and 3% TCN patch groups exhibited the best esophageal regeneration according to reepithelialization, neovascularization, and elastin texture around the implanted sites. Our antibiotic-releasing patch successfully consolidates the regenerative potential of esophageal muscle and mucosa and the antibacterial activity of TCN for 3D esophageal reconstruction. Impact statement Anastomosis site leakage and necrosis after pharyngoesophageal transplantation inevitably causes mortality because the mediastinum and neck compartments become contaminated. Herein, we present antibiotic-releasing pharyngoesophageal patch that prevents saliva leakage and has an antimicrobial effect. We have demonstrated antibiotic release profile and mechanical properties for esophageal transplantation. Upon esophageal transplantation of antibiotic-releasing polycaprolactone patches, antimicrobial effects and muscle regeneration around the graft sites were clearly identified in the group containing 1% and 3% of tetracycline. The esophageal graft led to the remarkable recovery throughout reepithelialization, neovascularization, and elastin texture of around the implanted sites. We believe that current system is capable of various applications that require antibacterial in vivo.

Effect of the Addition of Alginate and/or Tetracycline on Brushite Cement Properties.

Calcium phosphate cements have the advantage that they can be prepared as a paste that sets in a few minutes and can be easily adapted to the shape of the bone defect, which facilitates its clinical application. In this research, six formulations of brushite (dicalcium phosphate dihydrated) cement were obtained and the effect of the addition of sodium alginate was analyzed, such as its capacity as a tetracycline release system. The samples that contain sodium alginate set in 4 or 5 min and showed a high percentage of injectability (93%). The cements exhibit compression resistance values between 1.6 and 2.6 MPa. The drug was released in a range between 12.6 and 13.2% after 7 days. The antimicrobial activity of all the cements containing antibiotics was proven. All samples reached values of cell viability above 70 percent. We also observed that the addition of the sodium alginate and tetracycline improved the cell viability.

Ultrasound-assisted synthesis of MIL-88(Fe) coordinated to carboxymethyl cellulose fibers: A safe carrier for highly sustained release of tetracycline

For stopping long-time harmful bacterial infection, designing a drug carrier with a highly prolonged release profile is a promising approach that is of interest to different biomedical areas. The subject of this work is to synthesis a novel carrier system through coordination of MIL-88(Fe) to carboxymethyl cellulose (CMC) for enhancing interaction between drug and carrier. We established an ultrasound-assisted synthetic method for in situ synthesis of MIL-88(Fe) in the presence of CMC resulting in CMC/MIL-88(Fe) composite. The CMC/MIL-88(Fe) was loaded with a high amount of Tetracycline (TC) by immersion of carrier to the TC aqueous solution. The release profile in the simulated physiological conditions, pH 7.4, revealed a low initial burst release followed by a sustained and prolonged release over 384 h. The in vitro cytotoxicity of CMC/MIL-88(Fe) against Human skin fibroblast (HFF-1) cells was calculated by MTT assay and showed a good cytocompatibility. The antibacterial activity was found for TC-loaded CMC/MIL-88(Fe) toward both E. coli and S. aureus with MIC 64 mg·ml−1.

Modular Microneedle Patch for Local Immunomodulation and Periodontal Tissue Regeneration

Periodontal diseases affect over 50% of people and are caused by microbial infection and the recruitment of destructive immune cells such as macrophages and T cells. Current therapies for periodontitis mainly deal with bacteria elimination, but immunomodulation and tissue regeneration remains a challenge. Here we developed a modular and multifunctional microneedle (MN) patch that can deliver small molecules and immunomodulatory cytokines into the local gingival tissue. This MN patch included a quickly dissolvable gelatin membrane for a burst release of tetracycline and biodegradable GelMA microneedles that contained poly(lactic-co-glycolic acid) nanoparticles and silica microparticles for a sustained release of tetracycline and cytokines respectively. Antibiotic release completely inhibited bacteria growth, and the sustained release of IL-4 and TGF-β induced the repolarization of anti-inflammatory macrophages and the formation of regulatory T cells in vitro. In vivo placement of MN patch into periodontal tissues not only reduced local inflammatory signals but also modulated local immune cells to promote tissue healing. This work demonstrated a modular MN delivery platform for immunomodulation and tissue regeneration, which will have broad applications in regenerative medicine.

Sponges containing tetracycline loaded-PLGA-zein microparticles as a periodontal controlled release device

This paper aimed to design collagen sponges containing tetracycline-loaded PLGA-zein microparticles with controlled release characteristics as an alternative for periodontal treatment. Tetracycline microparticles were prepared by spray-drying technique, while the sponges were prepared by their dispersion in collagen suspension and subsequent freeze-drying. Release studies of two microparticles compositions loaded and unloaded-collagen sponges were carried over a 10 days period. Antibiogram tests were used to ensure the sustained antibacterial activity against Staphylococcus aureus. SEM imagens demonstrated spherical and non-aggregated microparticles (2–5 μm) and their effective dispersion within the sponges, what together with the pronounced water sorption promoted by the collagen fibers enhanced the drug release from the unitary particles. The dissolution profiles showed a sustained-release pattern for both sponges and microparticles formulations, reaching in some cases almost the complete drug recovery. The sponge formulations increased the release of tetracycline up to 45 and 60% in the first 12 h, while their microparticles pairs released less than 30 and 10%, respectively, as a result of their aggregation. Antibiograms showed that the sponges sustained released tetracycline over 10 days and could represent an alternative for periodontal insertion as well as for those applications where the prevention and control of bacterial infections is needed. The incorporation of tetracycline microparticles to collagen sponges improved the release rates of this antimicrobial agent and therefore represents an alternative for controlled antimicrobial activity.

Collagen Scaffolds Containing Hydroxyapatite-CaO Fiber Fragments for Bone Tissue Engineering

Collagen (COL) and hydroxyapatite (HAp) are the major components of bone, therefore, COL-HAp composites have been widely used as bone substitutes to promote bone regeneration. We have reported that HAp-CaO fibers (HANFs), which were fabricated by a sol-gel route followed by an electrospinning technique, possessed good drug-loading efficiency and limited the burst release of tetracycline. In the present study, we used HANF fragments to evaluate the effects of COL-HANF scaffolds on MG63 osteoblast-like cell behaviors. COL-HANF composite scaffolds in which the average diameter of HANFs was approximately 461 ± 186 nm were fabricated by a freeze-drying process. The alkaline phosphatase activity and the protein expression levels of OCN and BSP showed that compared with COL alone, the COL-HANF scaffold promoted the differentiation of MG63 osteoblast-like cells. In addition, the bone regeneration ability of the COL-HANF scaffold was examined by using a rabbit condylar defect model in vivo. The COL-HANF scaffold was biodegradable and promoted bone regeneration eight weeks after the operation. Hence, we concluded that the COL-HANF scaffold has potential as a bone graft for bone tissue engineering.

Mesoporous Magnetic Carbon Adsorbents Prepared from Sugarcane Bagasse and Fe2+ and Fe3+ via Simultaneous Magnetization and Activation for Tetracycline Adsorption

Tetracycline (TC) is one of the pharmaceutical antibiotics most employed for human and veterinary use in Thailand. The release of TC is considered a threat to the aquatic environment; hence, it urgently needs to be efficiently removed from the water streams. One of the popular and effective methods of removal of TC is adsorption. Magnetic carbon composites derived from biomass-based materials have attracted attention as novel adsorbents for removal of toxic substances from aqueous solution. However, their preparation involves multi-step procedures, which is time and energy consuming. In this work, we have prepared novel magnetic carbon composites using sugarcane bagasse, abundantly wasted biomass from sugar industries, a mixture of Fe2+ and Fe3+, and NaOH, as a carbon precursor, source of magnetite particles (Fe3O4), and precipitating/activating agent, respectively. The facile preparation has been performed via a simultaneous magnetization and activation process in a single step. The effects of preparation conditions on physicochemical properties of the resulting materials were studied, discussed and optimized. A selected sample showed satisfactory magnetic stability due to the presence of Fe3O4 particles (confirmed by XRD) and high porosity, with a BET surface of 566 m2/g and mesopore fraction (pore size > 2 nm) of more than 84%, suitable to adsorb the large TC molecules. The adsorption performance towards TC was determined using batch adsorption experiments. The maximum TC adsorption on the selected sample was as high as 48.40 mg/g, outperforming many literature sorbents, while the magnetic stability can even be retained after complete adsorption.

Minimizing the residual antimicrobial activity of tetracycline after adsorption into the montmorillonite: Effect of organic modification

Variety of adsorbents have been developed and used for antibiotic separations (e.g. tetracycline), however, there is not enough information about the residual antimicrobial activity of adsorbed antibiotics. In this study, montmorillonite was modified using HDTMA and applied for adsorption of tetracycline in order to minimize the residual antimicrobial activity of tetracycline. Results revealed that despite the high adsorption capacity of the non-modified montmorillonite for tetracycline, high residual antimicrobial activity still remained which was probably correlated to the partial release of tetracycline from the montmorillonite structure. On the other hand, the adsorbed tetracycline onto HDTMA-modified montmorillonite had much weaker residual antimicrobial activity due to the strong attraction force between HDTMA and the tetracycline which minimize the chance of its desorption when releasing the complex in the environment. A series of changes on the HDTMA-modification process (by improvement of HDTMA arrangement in the interlayers of montmorillonite) enhanced the adsorption of tetracycline in the interlayer spaces of montmorillonite with the least residual antimicrobial activity of tetracycline and HDTMA-modified montmorillonite complex. Results of this study present a great enhancement in the adsorption of antibiotics to minimize the effect of antibiotics such as the development of antibiotic-resistant bacteria.

Characterization, in vitro antibacterial activity, and toxicity for rat of tetracycline in a nanocomposite hydrogel based on PEG and cellulose

Hydrogels are among the drug delivery systems that are used to modify drug release by the oral route. Inclusion of porous nanoparticles and cellulose nanofibers (CNF) in a hydrogel matrix structure improves the mechanical strength of the hydrogel and modifies drug release. CNF have been widely used for the preparation of biomedical systems because of low toxicity, biodegradability, and biocompatibility. Besides, a positive influence on mechanical and physical resistance is shown. In this study, nanocomposite hydrogels containing polyethylene glycol, Acrylamide, N, N′-methylene bis-acrylamide, and CNF are formulated, and then tetracycline was loaded into the hydrogels. Tetracycline release was measured using UV spectrometer. Morphology and microscopic structure of synthesized nanocomposites are studied using FE-SEM, XRD, and FTIR analyses. Moreover, the antibacterial activity of tetracycline nanocomposite hydrogels against Staphylococcus aureus and Escherichia coli was tested. Nanocomposite hydrogel oral toxicity test was performed in adult male Wistar rats. The results showed that the formulation has no significant statistical effect on the behavioral pattern, body weight, and clinical parameters of the experimental animals. Furthermore, pathological examination showed the normal structure of stomach and intestine. Antibacterial activity study showed that Staphylococcus aureus and E. Coli are sensitive to the formulated compound 3. Therefore, these formulations can be considered for future as oral drug delivery systems.

Lignin and Cellulose Blends as Pharmaceutical Excipient for Tablet Manufacturing via Direct Compression.

Extensive efforts are being made to find alternative uses for lignin (LIG). In the present work the use of this biopolymer as excipient to prepare tablets was studied. For this purpose, LIG was combined with microcrystalline cellulose (MCC) and used as excipients to prepare directly compressed tablets containing a model drug, tetracycline (TC). The excipients contained different concentrations of LIG: 100%, 75%, 50%, 25% and 0% (w/w). Two different compression forces were used (two and five tonnes). When formulations were prepared using LIG as the only excipient, tablets were formed, but they showed lower densities and crushing strength than the ones obtained with only MCC or LIG/MCC blends. Moreover, tablets prepared using five tonnes of compression force showed TC releases ranging from 40% to 70% of the drug loading. On the other hand, the tablets prepared using two tonnes of compression force showed a faster and more efficient TC release, between 60% and 90%. The presence of LIG in the tablets modified significantly the release profile and the maximum amount of TC released. Finally, a DPPH (2,2-diphenyl-1-picrylhydrozyl) assay was performed to confirm that the presence of LIG provided antioxidant properties to the formulations. Accordingly, LIG has potential as a pharmaceutical excipient.

Drug release and swelling behavior of magnetic iron oxide nanocomposite hydrogels based on poly(acrylic acid) grafted onto sodium alginate

In this paper, a novel iron oxide nanocomposite hydrogel was prepared by simultaneous formation of superparamagnetic iron oxide nanoparticles and cross-linking of poly(acrylic acid) grafted onto sodium alginate polysaccharide. The prepared optimized hydrogel was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy with energy-dispersive X-ray analysis, atomic force microscopy, and transmission electron microscopy. Moreover, swelling capacity of the obtained hydrogel was measured at different temperatures, different pHs, absorption under load, and magnetic field to assess the sensitivity of ION–PAA-g-NaAlg hydrogel. This hydrogel was also examined as a controlled drug delivery system. Doxorubicin and tetracycline (as model drugs) release was investigated at different pHs, different temperatures, and magnetic field. The release curves were nicely fitted by the Korsmeyer–Peppas equation, and the release is controlled by polymer relaxation process.

Alginate Gel Reinforcement with Chitin Nanowhiskers Modulates Rheological Properties and Drug Release Profile.

Hydrogels are promising materials for various applications, including drug delivery, tissue engineering, and wastewater treatment. In this work, we designed an alginate (ALG) hydrogel containing partially deacetylated chitin nanowhiskers (CNW) as a filler. Gelation in the system occurred by both the protonation of alginic acid and the formation of a polyelectrolyte complex with deacetylated CNW surface chains. Morphological changes in the gel manifested as a honeycomb structure in the freeze-dried gel, unlike the layered structure of an ALG gel. Disturbance of the structural orientation of the gels by the introduction of CNW was also expressed as a decrease in the intensity of X-ray diffraction reflexes. All studied systems were non-Newtonian liquids that violated the Cox-Merz rule. An increase in the content of CNW in the ALG-CNW hydrogel resulted in increases in the yield stress, maximum Newtonian viscosity, and relaxation time. Inclusion of CNW prolonged the release of tetracycline due to changes in diffusion. The first phases (0–5 h) of the release profiles were well described by the Higuchi model. ALG-CNW hydrogels may be of interest as soft gels for controlled topical or intestinal drug delivery.

Anti-bacterial efficacy via drug-delivery system from layer-by-layer coating for percutaneous dental implant components

Abstract Percutaneous medical devices are prone to bacterial contamination that causes dramatic clinical conditions. At the percutaneous level of dental implant systems, microbial pathogens induce biofilm formation that may result in bone resorption and dental implant loss. In view of peri-implantitis caused by bacterial inflammation at the percutaneous abutment region, we here establish a novel drug release system based on layer-by-layer (LbL)-deposited poly(acrylic acid) (PAA) and poly- l -lysine (PLL) coatings on titanium (Ti). Detailed multilayer coating characterization was performed by different microscopy and spectroscopy techniques to probe physical and chemical properties. Our data revealed a significant difference in roughness average between ten double layers coated (141 nm ±30) and uncoated Ti discs (115 nm ±40). Although roughness of the coatings increased significantly after immersion in water for 24 h at 37 °C, this physical property remained below 200 nm. Coating stability was confirmed under neutral and acidic pH, mimicking healthy and diseased/inflammatory environments, respectively. LbL coatings supported in vitro human keratinocytes growth, demonstrating absence of cytotoxic effects. Tetracycline (TC) showed an initial burst release under neutral and acidic conditions, which further demonstrated robust antibacterial efficacy against Porphyromonas gingivalis. However, a convenient pH-dependent 2-folds increase in TC release was observed for coatings incubated at pH = 4.5. Sustained TC release was observed from coatings up till 15 days of incubation in both pH conditions. These results demonstrate the potential application of this simple surface modification to leverage anti-bacterial efficacy at the percutaneous abutment region.

Drug release and biodegradability of electrospun cellulose nanocrystal reinforced polycaprolactone

In this paper, high molecular weight cellulose was used as the starting material for the synthesis of cellulose nanocrystal (CNC). Different analysis techniques such as FTIR, XRD, TGA, DLS, and AFM were used to characterize CNC synthesis. The synthesized CNC was incorporated in polycaprolactone solution and nanofibers were prepared under different conditions. Production conditions were optimized based on the diameter of nanofibers using response surface methodology (RSM). Based on our results, the optimal condition is electrospinning of 16% PCL polymer solution at 17 kV and a 0.9 ml/h feed rate, which yields nanofibers with a diameter of 233 nm. The effects of CNC content on morphological, mechanical and thermal properties were investigated. Results also showed that CNC incorporation in PCL nanofibers enhances biodegradability. SEM, DSC, tensile, and biodegradability results showed that the nanofibers prepared from PCL solution containing 1% CNC have optimal mechanical and degradation behaviors. We also studied and modeled release of tetracycline from nanofiber mats, based on the assumption of rate limiting diffusion from the nanofibers, with a fraction of release delayed by drug sequestration. Results showed that the final drug release is decreased in CNC-incorporated nanofibers.

Fabrication and Characterization of Strontium-Substituted Hydroxyapatite-CaO-CaCO₃ Nanofibers with a Mesoporous Structure as Drug Delivery Carriers.

Hydroxyapatite (HAp) is the main inorganic component and an essential part of hard bone and teeth. Due to its excellent biocompatibility, bioactivity, and osteoconductivity, synthetic HAp has been widely used as a bone substitute, cell carrier, and therapeutic gene or drug carrier. Recently, numerous studies have demonstrated that strontium-substituted hydroxyapatite (SrHAp) not only enhances osteogenesis but also inhibits adipogenesis in mesenchymal stem cells. Mesoporous SrHAp has been successfully synthesized via a traditional template-based process and has been found to possess better drug loading and release efficiencies than SrHAp. In this study, strontium-substituted hydroxyapatite-CaO-CaCO3 nanofibers with a mesoporous structure (mSrHANFs) were fabricated using a sol–gel method followed by electrospinning. X-ray diffraction analysis revealed that the contents of CaO and CaCO3 in the mSrHANFs decreased as the doping amount of Sr increased. Scanning electron microscopy (SEM) images showed that the average diameter of the mSrHANFs was approximately 200~300 nm. The N2 adsorption–desorption isotherms demonstrated that the mSrHANFs possessed a mesoporous structure and that the average pore size was approximately 20~25 nm. Moreover, the mSrHANFs had excellent drug- loading efficiency and could retard the burst release of tetracycline (TC) to maintain antibacterial activity for over 3 weeks. Hence, mSrHANFs have the potential to be used as drug carriers in bone tissue engineering.

Decreased <em>Porphyromonas gingivalis</em> adhesion and improved biocompatibility on tetracycline-loaded TiO<sub>2</sub> nanotubes: an in vitro study

BackgroundTitanium dioxide (TiO2) nanotubes are often used as carriers for loading materials such as drugs, proteins, and growth factors.Materials and methodsIn this study, we loaded tetracycline onto TiO2 nanotubes to demonstrate its antibacterial properties and biocompatibility. The two-layered anodic TiO2 nanotubes with a honeycomb-like porous structure were fabricated by using a two-step anodization, and they were loaded with tetracycline by using a simplified lyophilization method and vacuum drying. Their physical properties, such as chemical compositions, wettability, and surface morphologies of the different samples, were observed and measured by X-ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electron microscopy (SEM). The in vitro growth behaviors of mouse bone marrow stromal cells (BMSCs) on these substrates were investigated.ResultsThe TiO2 nanotube (NT) substrates and the tetracycline-loaded TiO2 nanotube (NT-T) substrates revealed a crucial potential for promoting the adhesion, proliferation, and differentiation of BMSCs. Similarly, the NT-T substrates displayed a sudden release of tetracycline in the first 15 minutes of their administration, and the release tended to be stable 90 minutes later. The antibacterial performances of the prepared substrates were assessed with Porphyromonas gingivalis. The result showed that NT and NT-T substrates had antibacterial capacities.ConclusionOverall, this research provides a promising method with potential for clinical translation by allowing local slow release of antimicrobial compounds by loading them onto constructed nanotubes.