Characterization of a Toothpaste Containing Bioactive Hydroxyapatites and In Vitro Evaluation of Its Efficacy to Remineralize Enamel and to Occlude Dentinal Tubules

Demineralization of dental hard tissues is a well-known health issue and the primary mechanism responsible for caries and dentinal hypersensitivity. Remineralizing toothpastes are nowadays available to improve conventional oral care formulations regarding the prevention and repair of demineralization. In this paper, we analyzed the chemical-physical features of a commercial toothpaste (Biosmalto Caries Abrasion and Erosion, Curasept S.p.A., Saronno, Italy), with particular attention paid to the water-insoluble fraction which contains the remineralizing bioactive ingredients. Moreover, the efficacy of the toothpaste to induce enamel remineralization and to occlude dentinal tubules has been qualitatively and semiquantitatively tested in vitro on human dental tissues using scanning electron microscopy and X-ray microanalysis. Our results demonstrated that the water-insoluble fraction contained silica as well as chitosan and poorly crystalline biomimetic hydroxyapatite doped with carbonate, magnesium, strontium, and fluoride ions. The formulation showed excellent ability to restore demineralized enamel into its native structure by epitaxial deposition of a new crystalline phase in continuity with the native one. It was also able to occlude the dentinal tubules exposed completely by acid-etching. Overall, this study demonstrated that the tested toothpaste contained a biomimetic ionic-substituted hydroxyapatite-based active principle and that, within the in vitro conditions analyzed in this study, it was effective in dental hard tissue remineralization

Synthetic Crysotile Nano-Crystals as a Reference Standard to Investigate Surface-Induce Serum Albumin Structural Modifications

Geoinspired synthetic chrysotile, which represents an ideal asbestos reference standard, has been utilized to investigate homomolecular exchange of bovine serum albumin (BSA), the major plasma protein, between the adsorbed and dissolved state at the interface between asbestos fibers and biological medium. FTIR spectroscopy has been used to quantify BSA structural modifications due to surface adhesion on chrysotile fibers as a function of the surface coating extent. Circular dichroism spectroscopy has been used to investigate the adsorption/desorption equilibrium through analysis of the BSA structural perturbations after protein desorption from chrysotile surface. Data results show clearly that in the solid state BSA modifications are driven by surface interaction with the substrate, following a bimodal adsorption evidenced by two different binding constants. On the other hand, BSA desorbed in solution is able to rearrange, in the lack of substrate, although keeping irreversible modifications with respect to the native species. The lack of regaining its native structure certainly affects albumin interaction with biological environment. The present investigation on the stoichiometric synthetic geoinspired chrysotile nanocrystals is the first approach toward a deeper attempt to use standard synthetic chrysotile reference samples in mimicking the behavior of asbestos fibers and allows to better understand their interaction with a biological environment

Bioinspired negatively charged calcium phosphate nanocarriers for cardiac delivery of MicroRNAs

Aim: To develop biocompatible and bioresorbable negatively charged calcium phosphate nanoparticles (CaP-NPs) as an innovative therapeutic system for the delivery of bioactive molecules to the heart. Materials & methods: CaP-NPs were synthesized via a straightforward one-pot biomineralization-inspired protocol employing citrate as a stabilizing agent and regulator of crystal growth. CaP-NPs were administered to cardiac cells in vitro and effects of treatments were assessed. CaP-NPs were administered in vivo and delivery of microRNAs was evaluated. Results: CaP-NPs efficiently internalized into cardiomyocytes without promoting toxicity or interfering with any functional properties. CaP-NPs successfully encapsulated synthetic microRNAs, which were efficiently delivered into cardiac cells in vitro and in vivo. Conclusion: CaP-NPs are a safe and efficient drug-delivery system for potential therapeutic treatments of polarized cells such as cardiomyocytes

Calcium phosphate particles coated with humic substances: A potential plant biostimulant from circular economy

Nowadays, the use of biostimulants to reduce agrochemical input is a major trend in agriculture. In this work, we report on calcium phosphate particles (CaP) recovered from the circular economy, combined with natural humic substances (HSs), to produce a plant biostimulant. CaPs were obtained by the thermal treatment of Salmo salar bones and were subsequently functionalized with HSs by soaking in a HS water solution. The obtained materials were characterized, showing that the functionalization with HS did not sort any effect on the bulk physicochemical properties of CaP, with the exception of the surface charge that was found to get more negative. Finally, the effect of the materials on nutrient uptake and translocation in the early stages of development (up to 20 days) of two model species of interest for horticulture, Valerianella locusta and Diplotaxis tenuifolia, was assessed. Both species exhibited a similar tendency to accumulate Ca and P in hypogeal tissues, but showed different reactions to the treatments in terms of translocation to the leaves. CaP and CaP\u2013HS treatments lead to an increase of P accumulation in the leaves of D. tenuifolia, while the treatment with HS was found to increase only the concentration of Ca in V. locusta leaves. A low biostimulating effect on both plants\u2019 growth was observed, and was mainly scribed to the low concentration of HS in the tested materials. In the end, the obtained material showed promising results in virtue of its potential to elicit phosphorous uptake and foliar translocation by plants

On the use of superparamagnetic hydroxyapatite nanoparticles as an agent for magnetic and nuclear in vivo imaging

The identification of alternative biocompatible magnetic NPs for advanced clinical application is becoming an important need due to raising concerns about iron accumulation in soft issues associated to the administration of superparamagnetic iron oxide nanoparticles (NPs). Here, we report on the performance of previously synthetized iron-doped hydroxyapatite (FeHA) NPs as contrast agent for magnetic resonance imaging (MRI). The MRI contrast abilities of FeHA and Endorem® (dextran coated iron oxide NPs) were assessed by 1H nuclear magnetic resonance relaxometry and their performance in healthy mice was monitored by a 7 Tesla scanner. FeHA applied a higher contrast enhancement, and had a longer endurance in the liver with respect to Endorem® at iron equality. Additionally, a proof of concept of FeHA use as scintigraphy imaging agent for positron emission tomography (PET) and single photon emission computed tomography (SPECT) was given labeling FeHA with 99mTc-MDP by a straightforward surface functionalization process. Scintigraphy/x-ray fused imaging and ex vivo studies confirmed its dominant accumulation in the liver, and secondarily in other organs of the mononuclear phagocyte system. FeHA efficiency as MRI-T2 and PET-SPECT imaging agent combined to its already reported intrinsic biocompatibility qualifies it as a promising material for innovative nanomedical applications. STATEMENT OF SIGNIFICANCE: The ability of iron-doped hydroxyapatite nanoaprticles (FeHA) to work in vivo as imaging agents for magnetic resonance (MR) and nuclear imaging is demonstrated. FeHA applied an higher MR contrast in the liver, spleen and kidneys of mice with respect to Endorem®. The successful radiolabeling of FeHA allowed for scintigraphy/X-ray and ex vivo biodistribution studies, confirming MR results and envisioning FeHA application for dual-imaging

Inhalable microparticles embedding calcium phosphate nanoparticles for heart targeting: The formulation experimental design

Inhalation of Calcium Phosphate nanoparticles (CaPs) has recently unmasked the potential of this nanomedicine for a respiratory lung-to-heart drug delivery targeting the myocardial cells. In this work, we investigated the development of a novel highly respirable dry powder embedding crystalline CaPs. Mannitol was selected as water soluble matrix excipient for constructing respirable dry microparticles by spray drying technique. A Quality by Design approach was applied for understanding the effect of the feed composition and spraying feed rate on typical quality attributes of inhalation powders. The in vitro aerodynamic behaviour of powders was evaluated using a medium resistance device. The inner structure and morphology of generated microparticles were also studied. The 1:4 ratio of CaPs/mannitol led to the generation of hollow microparticles, with the best aerodynamic performance. After microparticle dissolution, the released nanoparticles kept their original size

Ex situ bioengineering of the rat thyroid using as a scaffold the three-dimensional (3D) decellularized matrix of the glandular lobe: clues to the organomorphic principle

Recently, we designed a bioreactor system for bioengineering ex situ (i.e. on the laboratory bench) a bioartificial thyroid gland suitable for transplantation. It is based on the organomorphic principle, i.e. the bioreactor mimics the macro-microscopic architecture of the thyroid stromal-vascular scaffold (SVS). To prove the reliability of this approach, we have initiated a pilot study using as a model the rat thyroid, and its natural decellularized 3D matrix to be eventually recellularized up to formation of a viable 3D thyroid lobe ex situ. Sprague-Dawley male rats (220-240 g) were used as thyroid donors. After penthobarbital anesthesia, rats were thyroidectomised and thyroid matrixes obtained by decellularization of the native SVS. Initially, we applied a sequence of liquid N2 freezing at - 80°C / thawing at 4°C for a total of 72 h, various washings with 0.02% trypsin / 0.05% EDTA for 1 h at 37°C, 3% Triton X-100 for 72 h at 4°C, and 4% deoxycholic acid for 24 h at 4°C, followed by sterilization with 0.1% peracetic acid, and 1% penicillin / streptomycin / fungizone for 24 h. Test matrixes were made electrondense with uranium / bismuth / lead counterstaining, and analyzed by microtomography (microTC). Primary thyroid cultures were prepared using enzymatic breaking of the native thyroid tissue. Cells were seeded at 19.000 / cm 2, and grown 72 h in low-glucose DMEM supplemented with 10% FBS / 5% FCS. Following trypsinization, 450.000 cells were harvested to coat the inner surface of the matrix. After 7 and 14 days, colonized matrixes were fixed in aldheydes and processed for light (LM), transmission (TEM) and scanning electron (SEM) microscopy. Culture supernatants were collected every 48 h, and thyroid hormones assessed with chemiluminescent immunoassays. Complete decellularization and maintenance of the 3D architecture of the thyroid SVS were achieved. Thyroid-derived cells were found to aggregate, link and give rise to intracytoplasmic cavities up to follicular coating, whereas secretory de-differentiation occurred. These results show that the 3D matrix of the rat thyroid can be used as a natural scaffold to recellularize the thyroid lobe with progenitor-like elements, supporting the validity of the organomorphic principle for ex situ bioengineering of a bioartificial thyroid gland. Grants FIL09, PRIN082008ZCCJX4, FIRB2010RBAP10MLK

Fluoride-doped amorphous calcium phosphate nanoparticles as a promising biomimetic material for dental remineralization

Demineralization of dental hard tissue is a widespread problem and the main responsible for dental caries and dentin hypersensitivity. The most promising strategies to induce the precipitation of new mineral phase are the application of materials releasing gradually Ca2+ and PO43- ions or mimicking the mineral phase of the host tissue. However, the design of formulations covering both processes is so far a challenge in preventive dentistry. In this work, we have synthesized innovative biomimetic amorphous calcium phosphate (ACP), which has been, for the first time, doped with fluoride ions (FACP) to obtain materials with enhanced anti-caries and remineralizing properties. Significantly, the doping with fluoride (F) did not vary the physico-chemical features of ACP but resulted in a faster conversion to the crystalline apatite phase in water, as observed by in-situ time-dependent Raman experiments. The efficacy of the as synthesized ACP and FACP samples to occlude dentinal tubules and induce enamel remineralization has been tested in vitro in human molar teeth. The samples showed good ability to partially occlude the tubules of acid-etched dentin and to restore demineralized enamel into its native structure. Results demonstrate that ACP and FACP are promising biomimetic materials in preventive dentistry to hinder demineralization of dental hard tissues