Biomimetic intrafibrillar mineralization of type I collagen with intermediate precursors-loaded mesoporous carriers

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An ORMOSIL-containing orthodontic acrylic resin with concomitant improvements in antimicrobial and fracture toughness properties

Global increase in patients seeking orthodontic treatment creates a demand for the use of acrylic resins in removable appliances and retainers. Orthodontic removable appliance wearers have a higher risk of oral infections that are caused by the formation of bacterial and fungal biofilms on the appliance surface. Here, we present the synthetic route for an antibacterial and antifungal organically-modified silicate (ORMOSIL) that has multiple methacryloloxy functionalities attached to a siloxane backbone (quaternary ammonium methacryloxy silicate, or QAMS). By dissolving the water-insoluble, rubbery ORMOSIL in methyl methacrylate, QAMS may be copolymerized with polymethyl methacrylate, and covalently incorporated in the pressure-processed acrylic resin. The latter demonstrated a predominantly contact-killing effect on Streptococcus mutans ATCC 36558 and Actinomyces naselundii ATCC 12104 biofilms, while inhibiting adhesion of Candida albicans ATCC 90028 on the acrylic surface. Apart from its favorable antimicrobial activities, QAMS-containing acrylic resins exhibited decreased water wettability and improved toughness, without adversely affecting the flexural strength and modulus, water sorption and solubility, when compared with QAMS-free acrylic resin. The covalently bound, antimicrobial orthodontic acrylic resin with improved toughness represents advancement over other experimental antimicrobial acrylic resin formulations, in its potential to simultaneously prevent oral infections during appliance wear, and improve the fracture resistance of those appliances.published_or_final_versio

Full quantum distribution of contrast in interference experiments between interacting one dimensional Bose liquids

We analyze interference experiments for a pair of independent one dimensional condensates of interacting bosonic atoms at zero temperature. We show that the distribution function of fringe amplitudes contains non-trivial information about non-local correlations within individual condensates and can be calculated explicitly using methods of conformal field theory. We point out interesting relations between these distribution functions, the partition function for a quantum impurity in a one-dimensional Luttinger liquid, and transfer matrices of conformal field theories. We demonstrate the connection between interference experiments in cold atoms and a variety of statistical models ranging from stochastic growth models to two dimensional quantum gravity. Such connection can be used to design a quantum simulator of unusual two-dimensional models described by nonunitary conformal field theories with negative central charges.Comment: 9 pages, 5 figures; Accepted for publication in Nature Physic

Crystalline phases involved in the hydration of calcium silicate-based cements: Semi-quantitative Rietveld X-ray diffraction analysis

Chemical comparisons of powder and hydrated forms of calcium silicate cements (CSCs) and calculation of alterations in tricalcium silicate (Ca3SiO5) calcium hydroxide (Ca(OH)2) are essential for understanding their hydration processes. This study aimed to evaluate and compare these changes in ProRoot MTA, Biodentine and CEM cement. Powder and hydrated forms of tooth coloured ProRoot MTA, Biodentine and CEM cement were subjected to X-ray diffraction (XRD) analysis with Rietveld refinement to semi-quantitatively identify and quantify the main phases involved in their hydration process. Data were reported descriptively. Reduction in Ca3SiO5 and formation of Ca(OH)2 were seen after the hydration of ProRoot MTA and Biodentine; however, in the case of CEM cement, no reduction of Ca3SiO5 and no formation of Ca(OH)2 were detected. The highest percentages of amorphous phases were seen in Biodentine samples. Ettringite was detected in the hydrated forms of ProRoot MTA and CEM cement but not in Biodentine

Systemic delivery of E6/7 siRNA using novel lipidic particles and its application with cisplatin in cervical cancer mouse models

Small interfering RNA (siRNA) shows great promise in cancer therapy, but its effectiveness in vivo still remains a crucial issue for its transition into the clinics. Although the successful use of polyethylene glycol (PEG)ylated lipidic delivery systems have already been reported, most of the formulation procedures used are labour intensive and also result in unstable end products. We have previously developed a simple yet efficient hydration-of-freeze-dried- matrix (HFDM) method to entrap siRNA within lipid particles, in which the products exhibited superior stability. Here, we show that these HFDM-formulated particles are stable in the presence of serum and can deliver siRNA efficiently to tumours after intravenous administration. Using these particles, around 50% knockdown of the target gene expression was observed in tumours. With the use of siRNA targeting the E6/7 oncogenes expressed in cervical cancer, we showed a 50% reduction in tumour size. This level of tumour growth suppression was comparable to that achieved from cisplatin at the clinically used dose. Overall, our results demonstrate the feasibility of using HFDM-formulated particles to systematically administer E6/7-targeted siRNA for cervical cancer treatment. The simplicity of preparation procedure along with superior product stability obtained from our method offers an innovative approach for the in vivo delivery of siRNA

Approaches in biotechnological applications of natural polymers

Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)

A Biometric Model for Mineralization of Type-I Collagen Fibrils

The bone and dentin mainly consist of type-I collagen fibrils mineralized by hydroxyapatite (HAP) nanocrystals. In vitro biomimetic models based on self-assembled collagen fibrils have been widely used in studying the mineralization mechanism of type-I collagen. In this chapter, the protocol we used to build a biomimetic model for the mechanistic study of type-I collagen mineralization is described. Type-I collagen extracted from rat tail tendon or horse tendon is self-assembled into fibrils and mineralized by HAP in vitro. The mineralization process is monitored by cryoTEM in combination with two-dimensional (2D) and three-dimensional (3D) stochastic optical reconstruction microscopy (STORM), which enables in situ and high-resolution visualization of the process

Zinc-modified nanopolymers improve the quality of resin-dentin bonded interfaces

Introduction: Demineralized collagen fibers at the hybrid layer are susceptible to degradation. Remineralization may aid to improve bond longevity. Objectives: The aim of the present study was to infiltrate zinc and calcium-loaded polymeric nanoparticles into demineralized dentin to facilitate hybrid layer remineralization. Materials and methods: Zinc or calcium-loaded polymeric nanoparticles were infiltrated into etched dentin, and Single Bond Adhesive was applied. Bond strength was tested after 24 h and 6 months storage. Nanomechanical properties, dyeassisted confocal laser microscopy, and Masson’s trichrome staining evaluation were performed to assess for the hybrid layer morphology, permeability, and remineralization ability after 24 h and 3 months. Data were analyzed by ANOVA and Student–Newman–Keuls multiple comparisons tests (p < 0.05). Results: Immediate bond strength was not affected by nanoparticles infiltration (25 to 30 MPa), while after 6 months, bond strengths were maintained (22 to 24 MPa). After 3 months, permeability occurred only in specimens in which nanoparticles were not infiltrated. Dentin remineralization, at the bottom of the hybrid layer, was observed in all groups. After microscopy analysis, zinc-loaded nanoparticles were shown to facilitate calcium deposition throughout the entire hybrid layer. Young’s modulus at the hybrid layer increased from 2.09 to 3.25 GPa after 3 months, in specimens with zinc nanoparticles; meanwhile, these values were reduced from 1.66 to 0.49 GPa, in the control group. Conclusion: Infiltration of polymeric nanoparticles into demineralized dentin increased long-term bond strengths. Zinc-loaded nanoparticles facilitate dentin remineralization within the complete resin–dentin interface. Clinical relevance: Resin–dentin bond longevity and dentin remineralization at the hybrid layer were facilitated by zincloaded nanoparticles.This work was supported by a grant, MINECO/FEDER MAT2014-52036-P