In this paper, the effect of cyanoguanidine (CNGE) for tailoring pore size during the soft-templating preparation of mesoporous carbon materials was studied. In consideration of cyclic utilization, the surface of the mesoporous carbon materials were doped with magnetic Fe3O4 particles. The characterization results (including TEM, XRD, BET, TGA and FT-IR) showed that adding CNGE did not destroy the ordered porous structure; instead, it changed the pore size from 2.98 nm to 9.42 nm. Besides, the mesoporous carbon materials exhibited a strong magnetic response owing to the dopant of Fe3O4 particles. With the increase in CNGE, some functional groups were added to the surface of the mesoporous carbon materials, which partly promoted the adsorption effect. The results indicated that adsorption approached equilibrium in the first 10 min and reached the maximum when the pore size was 5.89 nm. The kinetic of minocycline adsorption on magnetic ordered mesoporous carbon material could be interpreted by a pseudo-first-order model. The adsorption isotherms showed that the adsorption process was complex, combining physical and weak chemical adsorption, in good agreement with the Sips model.

Cheap and simple to make, calcium phosphate (CP), thanks to its unusual functional pleiotropy, belongs to the new wave of abundant and naturally accessible nanomaterials applicable as a means to various technological ends. It is used in a number of industries, including the biomedical, but its intrinsic antibacterial activity in the nanoparticle form has not been sufficiently explored to date. In this study we report on this intrinsic antibacterial effect exhibited by two distinct CP phases: an amorphous CP (ACP) and hydroxyapatite (HAp). The effect is prominent against a number of regular bacterial species, including S. aureus, S. epidermis, E. Faecalis, E. coli and P. aeruginosa, but also their multidrug-resistant (MDR) analogues. While ACP and HAp displayed similar levels of activity against Gram-negative organisms, ACP proved to be more effective against the Gram-positive ones, with respect to which HAp was mostly inert, yet this trend became reversed for the MDR strains. In addition to the intrinsic antimicrobial effect of CP nanoparticles, we have also observed a synergistic effect between the nanoparticles and certain antibiotics. Both forms of CP engaged in a synergistic relationship with a variety of concomitantly delivered antibiotics, including ampicillin, kanamycin, oxacillin, vancomycin, minocycline, erythromycin, linezolid and clindamycin, and enabled even antibiotics completely ineffective against particular bacterial strains to significantly suppress their growth. This relationship was complex, intensifying in activity proportionally to nanoparticle concentration, plateauing immediately after the introduction of nanoparticles in minute amounts or exhibiting concentration-dependent minima due to stress-induced biofilm formation depending on a particular CP phase, bacterial strain and antibiotic. These findings present grounds for the further optimization of CP properties and maximization of this intriguing effect, which could in the long run make this material comparable in activity to the inorganics of choice for this application, including silver, copper or zinc oxide, while retaining its superb safety profile and positive eukaryotic vs. prokaryotic cell selectivity.

This study aims the in vivo biological characterization of an innovative minocycline delivery system, based on polymethylmethacrylate bone cement. Bone cements containing 1% or 2.5% (w/w) minocycline were formulated and evaluated through solid-state characterization. Biological evaluation was conducted in vivo, within a rat model, following the subcutaneous and bone tissue implantation, and tissue implantation associated with Staphylococcus aureus is challenging. The assessment of the tissue/biomaterial interaction was conducted by histologic, histomorphometric and microtomographic techniques. Minocycline addition to the composition of the polymethylmethacrylate bone cement did not modify significantly the cement properties. Drug release profile was marked by an initial burst release followed by a low-dosage sustained release. Following the subcutaneous tissue implantation, a reduced immune-inflammatory reaction was verified, with diminished cell recruitment and a thinner fibro-connective capsule formation. Minocycline-releasing cements were found to enhance the bone-to-implant contact and bone tissue formation, following the tibial implantation. Lastly, an effective antibacterial activity was mediated by the implanted cement following the tissue challenging with S. aureus. Kinetic minocycline release profile, attained with the developed polymethylmethacrylate system, modulated adequately the in vivo biological response, lessening the immune-inflammatory activation and enhancing bone tissue formation. Also, an effective in vivo antibacterial activity was established. These findings highlight the adequacy and putative application of the developed system for orthopedic applications.

It is important to address the periodontitis-associated bacteria in the residual sub-gingival plaque after scaling and root planing (SRP) to successfully treat periodontitis. In this study, we explored the possibility of exploiting the ion pairing/complexation of minocycline, Ca2+, and sulfate/sulfonate-bearing biopolymers to develop an intrapocket delivery system of minocycline as an adjunct to SRP. Minocycline-calcium-dextran sulfate (Mino-Ca-DS) complex microparticles were synthesized from minocycline, CaCl2, and dextran sulfate. They were characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. An in vitro release study was conducted to evaluate the release kinetics of minocycline from these microparticles. Agar disk diffusion assays and biofilm-grown bacteria assays were used to access antibacterial capability. High loading efficiency (96.98±0.12%) and high loading content (44.69±0.03%) for minocycline were observed for these complex microparticles. Mino-Ca-DS microparticles achieved sustained release of minocycline for at least 9 days at pH 7.4 and 18 days at pH 6.4 in phosphate-buffered saline, respectively. They also demonstrated potent antimicrobial effects against Streptococcus mutans and Aggregatibacter actinomycetemcomitans in agar disk diffusion and biofilm assays. These results suggested that the ion pairing/complexation of minocycline, Ca2+ and sulfonate/sulfate-bearing biopolymers can be exploited to develop complex microparticles as local delivery systems for periodontitis treatment.

In the present study, an injectable in situ liquid crystal formulation was developed for local delivery of minocycline hydrochloride (MH) for chronic periodontitis treatment. The physicochemical properties, phase structures, in vitro drug release and pharmacodynamics of in situ liquid crystals were investigated. The optimal formulation (phytantriol (PT)/propylene glycol (PG)/water, 63/27/10, w/w/w) loaded with 20 mg/g MH was proved to be injectable. The precursor formulation can form a cubic phase gel in excess water in 6.97 ± 0.10 s. The results of in vitro drug release suggested the MH presented a sustained release for 4 days. Liquid crystal precursor formulation significantly reduced gingival index, probing depth and alveolar bone loss compared to the model group (p < 0.01). Besides, the pathological characteristics of model rats were improved. The results suggested that MH-loaded in situ cubic liquid crystal possessed of sustained release ability and periodontal clinical symptoms improvement. The developed in situ cubic liquid crystal may be a potentially carrier in the local delivery of MH for periodontal diseases.

Candida carriage was reported to be common in oral cancer patients, with C. albicans being the predominant species. The prevalence of diseases caused by Candida species have been found to increase in recent years.