Advances in nanotechnology observe new applications in many areas. Recently a great extent of research has been focused on the study of magnetic nanoparticles due to their potential application in areas such as bioscience and medicine. Magnetic nanoparticles are frequently used in biomedical and biotechnology applications since these particles associated to a given medicine are good candidates for drug release.

In this work zeta potential measurements of both hexagonal barium ferrites (magnetic nanoparticles), and an antibiotic known as tetracycline were carried out. The knowledge of the measured values establishes the possibility of bringing the two particles together in order to adsorb the tetracycline on the magnetic nanoparticles, since the surface charge play an essential role in the adsorption of the pharmaceutical drug on nanomaterials (i.e., tetracycline on barium ferrites).

Experimental results show the feasibility to adsorb tetracycline nanoparticles on barium hexaferrite solids at pH 7.0, based on the knowledge of the opposite electrical surface charge of the two solid species through the zeta potential measurement.

Combining Bisphophonates (BPs) and Calcium Phosphate Cement (CPC) to form a new medical device for the local treatment of Osteoporosis is a promising challenge. Our formulation was optimized from an apatitic-type CPC and we have shown that the best solution consists in introducing the bisphosphonate (Alendronate) in the calcium deficient apatite (CDA), a solid component of the cement, through a chemical exchange reaction. The cement obtained was characterized by 31P NMR and high frequency impedance for monitoring the CPC setting. The presence of Alendronate in the cement was also demonstrated by 31P NMR which has been also used to characterize the chemical transformation of α-TCP (main component of the apatitic cement) during the setting process. BP absorption/desorption experiments have been realized on cement blocks, under continuous flow condition, to model the release profile of the Alendronate. In vivo experiments showed promising results in terms of resorbability of the Alendronate–loaded cement while promoting new bone formation. The same methodology is considered to introduce gallium, a potential inhibitor of osteoclastic resorption, in a CPC formulation. First experiments have shown that gallium can be incorporated in calcium phosphate ceramics (i.e. β-TCP) where gallium is part of the network.

Two types of porous materials derived from emulsion templates are described as potential scaffolds for tissue engineering. Novel oil-in-water particle stabilised, Pickering High Internal Phase Emulsions (HIPE) stabilised with hydroxyapatite (HAp) nanoparticles were prepared and polymerised to form stable polyHIPEs. By adding a water soluble glycidyl methacrylate (GMA) derivatised dextran as monomer to the continuous aqueous phase of the HIPEs, these Pickering-HIPEs stabilised by nontoxic biocompatible HAp nanoparticles, can be used as templates to manufacture interconnected high porosity macroporous hydrogels. A second type of emulsion templated “poly”HIPE was prepared without the need for covalent crosslinking chemistry which was replaced by a thermally-induced non-covalent scaffold forming process (thermoHIPE). These scaffolds form close to body temperature and potentially offer a new approach to the formation of injectable scaffolds for tissue engineering.

In the present work, the adsorption of albumin and fibrinogen on Ta, Nb, Ti and Zr oxidesthin films deposited on Si (100) wafers by magnetron sputtering was studied in order to get a better understanding of the correlation among the surface properties of these oxides and the protein adsorption phenomena on their surfaces. The surface energy, hydrophobicity, chemical composition, roughness and atomic order of the films were characterized. The films were immersedfor 45 minutes in single protein solutions; either albumin or fibrinogenand the adsorbed protein layer on the films was studied ex-situ in a dry ambient using bothX-ray photoelectron spectroscopy and atomic force microscopy.

The adsorption of albumin and fibrinogen on the films modified the surface morphology and decreased the surface roughness for all the four different metal oxides. The XPS results confirmed the presence of the protein on the surface of the films and showed that the two proteins studied were adsorbed without undergoing a major chemical decomposition. A correlation between the surface roughness,the polar component of the surface energy of the films and the atomic percentage of nitrogen on the films after protein adsorption, an indirect signal of the amount of protein adsorbed, was found for albumin and fibrinogen adsorption on Ta, Nb and Ti oxides; the largest the roughness or the polar component the largest amount of adsorbed protein.

The incomplete fit of full cast crown restorations remains a critical problem for dentists, leading many researchers to study this problem. Marginal and internal accuracy of fit is valued as one of the most important criteria for the clinical quality and success of complete crowns. The geometry of tooth preparation has been the subject of many debates without clear evidence that one type of tooth preparation or method of fabrication provides consistently superior marginal fit. The objective of this study was to evaluate, by finite element analysis, the influence of different marginal geometries (shoulderless, chamfer, shoulder) on the stress distribution in teeth prepared for cast metal crowns.

A 3D model of a molar was created: intact teeth, unrestored teeth different marginal geometries: shoulderless, with chamfer, with shoulder preparations; the same tooth restored full cast metal crowns. These were exported in Ansys finite element analysis software for structural simulations.

The values of the maximal equivalent stress were higher for the shoulder preparations, but distributed under the preparation line. Regarding the stress distribution for the other two preparation designs, the largest area is present for the chamfer preparation, followed by the shoulderless preparation.

Within the limitations of the present study, the shoulder preparation is the recommended preparation design from biomechanical point of view. It is followed by the shoulderless preparation. Chamfer margins are less favorable only from this point of view. In light of these results, consideration should be given to the designs from prophylactic and biological points of view, with emphasis on conserving tooth structure and preventing preparation trauma.

Two methods based on fractal image analysis were used to extract the architectural features of the anisotropic structure of trabecular bone from scanning electron microscope (SEM) images of sliced bone samples in order to assess the bone’s medical condition. Two methods applied were Box-Counting (BC) and Fast Fourier Transform (FFT). Tests with synthetic images of known fractal dimension aided in the interpretation of the fractal dimension (FD) profiles. Samples from L3 vertebrae were removed from Mexican male donors at the time of necropsy and evaluated using computed axial tomography (CAT) scans. Three sliced samples in normal, osteopenic and osteoporotic conditions were identified in order to compare both methods across a range of samples. The three-dimensional projection of the FD profile reflected a multifractal behavior of the trabecular architecture and clearly showed the differences in texture between the three conditions studied: normal, osteopenic and osteoporotic. In addition, the results suggest that the FFT method provides an accurate and consistent estimated for characterizing trabecular bone than the BC method.

Taxol (Paclitaxel) is a very potent anticancer drug used in chemotherapy treatments. Due to its hydrophobic nature, toxic solubilizing agents are used to administer the drug via intravenously. However, this systemic administration is associated with toxic side effects and drug limited efficacy. An alternative to these problems are polymeric micelles. The effectiveness of this drug delivery system is related to its size, modification of pharmacokinetics, drug delivery control and toxicity reduction. In this study, micelles based on methoxy Poly(ethylene glycol)-block-Poly(ε-caprolactone) (mPEG-b-PCL) copolymer loaded with Taxol were synthesized thorough an uncommon method namely powder formulation, using tert-butanol as co-solvent, to our knowledge no reported previously for these micells. Taxol was conjugated to the hydrophobic block of mPEG-b-PCL copolymer. Characterization of this system was done by means of Fourier Transform Infrared Spectroscopy (FT-IR) and Field Emission Scanning Electron Microscopy (FESEM), observing good results as compared to previous reports.

Cardiac disease is the main cause of death in men and women in México and the U.S.A. When heart muscle suffers an injury, i.e. cardiac infarction, the tissue dies and is replaced by a fibrotic scar that does not allow for normal organ function. To alleviate scar tissue, the objective of this work was to investigate and synthesize polyurethane ureas from polycaprolactone diol, methylene bis(4-cyclohexilisocyanate), and butanediamine with different hard segment contents, characterize them, and prove their biocompatibility by seeding SCA-1+/CD45- cardiac progenitor cells obtained from mice cardiospheres. Ultimately, this work aims to explore how polyurethane urea elastomers can aid in therapeutic cardiac tissue regeneration.

The paper presents the results of PL spectrum analysis of CdSe/ZnS QDs covered by PEG polymer with and without bioconjugation to bio-molecules .– the Osteopontin antibodies. Commercial CdSe/ZnS QDs used in the study are characterized by the color emission with the maximum at 640 nm (1.96 eV) at 300K. It is shown that PL spectra of nonconjugated QDs can be presented as a superposition of PL bands related to exciton emission in the CdSe core (1.96 eV) and some high energy PL bands (in the spectral range 2.37 .– 3.00 eV). The comparative study of PL spectrum at high (300K) and low (10K) temperatures has testified that high energy PL bands deal with electronhole emission via interface states at the CdSe/ZnS/polymer interfaces.

It is revealed that the QD bioconjugation to the anti Osteopontin antibody is accompanied by the change dramatically in PL spectra. Main features of PL spectrum transformstions deal with decreasing the PL intensity of interface related PL bands and the rise of intensity of CdSe core related PL bands. The explanation of mentioned effects has been proposed on the base of re-charging of interface related states at the bioconjugation process.

Physical properties of porous membranes made of biocompatible and biodegradable polymers have been studied. The membranes are intended to be used as scaffolds for the regeneration of soft and hard tissues. Polylactides, polycaprolactone and some of their derivates are biocompatible as well as biodegradable materials, and are used for the preparation of nanofibers and nanoporous membranes. These membranes also have comparative advantages as cellular scaffolds for tissue engineering since they can be prepared to mimic the morphology of the extra cellular matrix.

Chemical, physical, and biological properties of microfibers and scaffolds of polylactic acid (PLLA), as well as PLLA modified with hydroxyapatite nanoparticles and collagen (Col) are reported in this paper. The microfibers and the scaffolds were prepared by electrospinning. Morphology, diameter and porosity of the scaffold were determined by scanning electron microscopy and an image analyzer program. The microfibers are semicrystalline showing a shell of crystalline nanofibrils. The diameter of the fibers varied between 100 and 800 nm and the porous area of the membrane is between 60 and 80%. The mechanical properties of the microfibers and scaffolds were evaluated by microtensile tests and their behavior was simulated by using an original multiscale asymptotic homogenization model. Cultures of mesenchymal stem cells were used to evaluate their biological activity. Cell adhesion was observed in the modified PLLA scaffolds with grafted hydroxyapatite.

Osteoarthritis is a very complex illness of the joints that affects cartilage and subcondral bone. At the last years, researching has been focused in the development and characterization of composite materials, evaluating their structural properties. Some o those composite materials are constituted by organic and inorganic compounds forming hybrids. These materials can improve their properties due to the interaction of reinforcement hard particles in the polymeric matrix. The interest on the composite biomaterials has been increased on the biomedical applications such as tissue regenerating based in synthetic polymers with biodegradable and biocompatible properties whose can be reinforced by calcium phosphates. In this sense, hydroxyapatite [Ca10(PO4)6(OH)2] is often used for biological implants due its mineral phase similitude with bone microstructure and tissue compatibility. Similarly, polylactic acid (PLA) is a used polymer for implant applications due physicochemical and biocompatibility properties, and short degradation time also. In order to obtain a composite that can be used as a regenerating material on the osteoarthritis problem, in this work a (90/10 wt.%) polylactic/hydroxyapatite hybrid composite was produced by chemical synthesis and characterized by X-ray diffraction, SEM, FT-IR and TGA/DSC techniques.

This paper presents the analysis of Raman scattering spectra of CdSe/ZnS QDs covered by the amine-derivatized polyethylene glycol (PEG) polymer with and without bioconjugation to bio-molecules: mouse ovarian cancer (OC 125) antibodies (mab). Commercial CdSe/ZnS QDs used in the study are characterized by the color emission with the maximum at 525 nm (2.36 eV) at 300K. Samples of CdSe/ZnS QDs (bio-conjugated and non -conjugated) in the form of an 5 mm-size spot were dried on a polished surface of crystalline Si substrate to ensure a low level of light scattering background.

Raman scattering spectra of non-conjugated QDs can be presented as a superposition of Raman lines: 212.2, 222.5, 308.3, 440.3, 521.0, 618.0, 667.8 943.5, 986.7, cm-1 related to the CdSe core and silicon substrate. The Raman lines 1003.9, 1317.8, 1452.9, 1656.8, 2870.4, 2931.8 and 3059.9 cm-1 deal with the vibration of COH, CH and OH groups of polymer, which covered QDs, were detected additionally. It is revealed that the QD bio-conjugation to the OC 125 antibodies is accompanied with the changes in the intensity of all types of Raman lines: related to the CdSe core, silicon substrate and polymer groups. The explanation of bioconjugation effects has been proposed and discussed.

Cast metal inlays have overall characteristics unavailable in any other restorative procedure, including low restoration wear, low wear of opposing teeth, lack of breakage, burnishability, malleability, and proven long term service. They replace missing teeth structures, without doing anything to reinforce the remaining structures. Stress concentrations can manifest themselves in various forms of failures. The aim of the study was to investigate the effect of preparation design on stress distribution in molars with different class II preparations and restored with cast metal inlays.

3D models of premolars and molars were created: intact teeth, unrestored teeth with class II preparations with different tapers (between 0 and 10 degree); the same teeth restored with metalic inlays. The geometries of the intact teeth were obtained by 3D scanning using a manufactured device. With Rhinoceros modeling program the preparations and the appropriately inlays were designed. These were exported in Ansys finite element analysis software for structural simulations. Stresses were registred around the occlusal contact areas. For the studied cases, the stress values were not significant influenced by the taper of the preparation. In the teeth restored with cast metal inlays, the von Mises equivalent stress values were similar to those in the intact tooth.

From biomechanical point of view, it was demonstrated that class II cast metal inlays on posterior teeth restore the original strength of the teeth. Taking into account the other characteristics of these restorations, they remain the standard of care for long-term rehabilitations. A taper between 0 and 10 degree of the preparation is not decisive for the stress values.

The purpose of this study was to investigate the in vivo biocompatibility of a new composite made from collagen and liposomes coated with plant derived polysaccharide using a rat subcutaneous implantation model. Histological observation has shown that after five days post-implantation, granulation tissue with vascular dilatation and inflammatory cell infiltration was formed adjacent to the implanted scaffold. After two weeks post-implantation, scaffold was highly infiltrated with cells and many of multinucleated giant cells were found to be aligned along the implant/tissue interface. At four weeks the scaffold was completely infiltrated with cells and a fibrous connective capsule isolate the implanted scaffold from the surrounding tissue. The inflammatory response to the implanted scaffold was assessed by immunohistochemical staining for interleukin 1β. IL-1β was demonstrated early in the post-implantation period (five days), but after two weeks, the intensity of IL-1β staining was on the decline. In vivo studies based on histological and immunohistochemical observations showed that throughout the period of implantation, composite scaffold was well tolerated by the host animals and immune responses to the implant were moderate. The observations are consistent with the normal wound healing response to subcutaneous implantation of biomaterials. The results from the in vivo study indicate a good biocompatibility for porous scaffold made from collagen and liposomes coated with plant derived polysaccharide.

In this research, we describe the electrospinning processing of polylactic acid (PLA) and the influence of silver nanoparticles on the morphology and microstructure of produced non woven membranes thus produced. The PLA was electrospun from a chloroform solution and a filamentary and granular morphology was obtained, the filaments having an average diameter of 1.25 μm, When silver nanoparticles (of ca. 12 nm size) were incorporated, the filaments diameter was reduced to an average of 0.65 μm, and the density of beads was also reduced. The membranes were rather amorphous, as revealed by X-ray scattering, presumably due to the quenching process associated with the electrospinning process. Water contact angle measurements showed that silver nanoparticles induced significant hidrophobicity in the membranes as neat PLA membrane had a contact angle of 54° and PLA/Ag membrane exhibited an angle of 115°.