Tese de doutoramento em Ciência e Tecnologia de Materiais (ramo de conhecimento em Engenharia de Tecidos - Materiais Híbridos); In the recent years, great progress has been done in the emerging field of tissue engineering. Despite
the important advances the performance of cells-scaffold constructs, one of the several tissue
engineering approaches, remains limited in part due to the need for optimize cell culture techniques and
culture media. Nanocarrier systems have generated a significant amount of interest in the ex vivo cell
maintenance, and control of the cellular fate in vivo mainly due to their internalization efficiency, drug
loading capacity, and to favorably modulate the solubility and pharmacokinetics of drugs. Dendrimers
are synthetic, monodispersive, spherical and highly branched macromolecules that present unique
advantages and fulfills most requirements as carriers for drug delivery; however, it has been found that
high generation dendrimers are often cytotoxic. Thus, in this thesis we focused our attention in this
fundamental problem and explore the development of novel nanobiomaterials based on the grafting of
carboxymethylchitosan (CMCht) onto low generation poly(amidoamine) (PAMAM) dendrimers, the socalled
CMCht/PAMAM dendrimer nanoparticles. These macromolecular vehicles were developed to
explore a new concept consisting on the intracellular and controlled delivery of bioactive molecules
aimed at control stem cells functions in a more effective manner ex vivo...
Strategies in Tissue Engineering and Regenerative Medicine are often based on the use of biomaterials able to support and control cellular activity. Two aspects should be considered in the development of high performance bioinstructive biomaterials. (i) The inherent complexity associated with the multiple possibilities in the biomaterials/cells selection, usually addressed using high-throughput combinatorial tests; and (ii) the unpredictability of the biological outcome of a particular solution. The last facet requires a rational decomposition of the main spatial and temporal cues at the cellular level that drive new-tissue formation upon injury, to be then transposed into adequate biomaterialsâ design. Several nano/micro-technologies may be used to process biomaterials with different shapes and sizes, permitting to engineer biomimetic and hierarchical biomedical devices. As a particular case study, the layer-by-layer assembly method is suggested as a versatile and robust framework to formulate multifunctional and tunable polymer-based biomaterials able to address this exercise of deconstruction and reconstruction.
Nanobiomaterials based on superhydrophilic vertically-aligned multi-walled carbon nanotubes (VAMWCNT-O2) are promising for their properties and bone tissue biocompatibility. VAMWCNT-O2 films with nanohydroxyapatite (nHAp) aim to improve mechanical properties and biocompatibility of this new nanocomposite due to its resemblance to bone matrix structure. This study aimed to produce in vitro biomineralized nHAp/VAMWCNT-O2 nanocomposites using simulated body fluid (SBF) with two different pHs (6.10 and 7.40) during 7 days to obtain a new surface design with higher crystalinity and better morphology of nHAp/VAMWCANT-O2 nanocomposites. The objective is to obtain biomineralized nanobiomaterials to enable its applicability as "scaffold" to cellular support and consequent bone tissue formation, accelerating the osseointegration. Layer densification has been achieved due to polycrystalline nanoapatites deposition on surface and between the biomineralized nHAp/VAMWCNT-O2 nanocomposites, without any heat treatment. Therefore, through its characteristics and properties these nanocomposite applications can be considered extremely viable for acceleration of in vivo regenerative processes.
The heterologous expression and purification of membrane proteins represent major limitations for their functional and structural analysis. Here we describe a new method of incorporation of transmembrane proteins in planar lipid bilayer starting from 1 pmol of solubilized proteins. The principle relies on the direct incorporation of solubilized proteins into a preformed planar lipid bilayer destabilized by dodecyl-β-maltoside or dodecyl-β-thiomaltoside, two detergents widely used in membrane biochemistry. Successful incorporations are reported at 20°C and at 4°C with three bacterial photosynthetic multi-subunit membrane proteins. Height measurements by atomic force microscopy (AFM) of the extramembraneous domains protruding from the bilayer demonstrate that proteins are unidirectionally incorporated within the lipid bilayer through their more hydrophobic domains. Proteins are incorporated at high density into the bilayer and on incubation diffuse and segregate into protein close-packing areas. The high protein density allows high-resolution AFM topographs to be recorded and protein subunits organization delineated. This approach provides an alternative experimental platform to the classical methods of two-dimensional crystallization of membrane proteins for the structural analysis by AFM. Furthermore...
Cell-surface interactions play a crucial role for biomaterial application in orthopaedics.
It is evident that not only the chemical composition of solid substances influence cellular adherence,
migration, proliferation and differentiation but also the surface topography of a biomaterial.
The progressive application of nanostructured surfaces in medicine has gained increasing interest
to improve the cytocompatibility and osteointegration of orthopaedic implants. Therefore, the
understanding of cell-surface interactions is of major interest for these substances. In this review,
we elucidate the principle mechanisms of nano- and microscale cell-surface interactions in vitro for
different cell types onto typical orthopaedic biomaterials such as titanium (Ti),
cobalt-chrome-molybdenum (CoCrMo) alloys, stainless steel (SS), as well as synthetic polymers
(UHMWPE, XLPE, PEEK, PLLA). In addition, effects of nano- and microscaled particles and their
significance in orthopaedics were reviewed. The significance for the cytocompatibility
of nanobiomaterials is discussed critically.
Over the last decades, tissue engineering has demonstrated an unquestionable potential to regenerate damaged tissues and organs. Some tissue-engineered solutions recently entered the clinics (eg, artificial bladder, corneal epithelium, engineered skin), but most of the pathologies of interest are still far from being solved. The advent of stem cells opened the door to large-scale production of “raw living matter” for cell replacement and boosted the overall sector in the last decade. Still reliable synthetic scaffolds fairly resembling the nanostructure of extracellular matrices, showing mechanical properties comparable to those of the tissues to be regenerated and capable of being modularly functionalized with biological active motifs, became feasible only in the last years thanks to newly introduced nanotechnology techniques of material design, synthesis, and characterization. Nanostructured synthetic matrices look to be the next generation scaffolds, opening new powerful pathways for tissue regeneration and introducing new challenges at the same time. We here present a detailed overview of the advantages, applications, and limitations of nanostructured matrices with a focus on both electrospun and self-assembling scaffolds.
Nanoparticles have shown tremendous potential for effective drug delivery due to their tiny size and cell membrane penetration capabilities. Cellular targeting with nanoparticles is often achieved by surface modifications followed by ligand conjugation. However, the efficiency of the nanoparticles reaching the target cells and getting internalized depends on the stability of targeting ligands and the chemical nature of the ligand nanoparticle binding. Recent advancements in nanobiomaterials research have proven the superoxide dismutase (SOD) mimetic activity of cerium oxide nanoparticles (CNPs) in protecting cells against oxidative stress. Due to their excellent biocompatibility, CNPs can be used as potential drug carrier that can transport and release drugs to the malignant sites. Here we combine single molecule force spectroscopy (SMFS) and density functional theory (DFT) simulations to understand the interaction between transferrin, a ligand protein over-expressed in cancer cells, and CNPs. SMFS studies demonstrate an increase in the transferrin adhesion to the nanoparticles surface with an increase in positive zeta potential of CNPs. Binding energy values obtained from DFT calculations predict an increase in bond strength between the transferrin and CNPs upon surface protonation and charge modification. Transferrin conjugated CNPs were tested for their binding stability and preferential cellular uptake efficiency by incubating them with human lung cancer cells (A549) and normal embryo lung cells (WI-38). The results demonstrate the importance of tuning the surface properties of nanoparticles for better ligand adsorption and cellular uptake.
The interaction between cells and nanostructured materials is attracting increasing interest, because of the possibility to open up novel concepts for the design of smart nanobiomaterials with active biological functionalities. In this frame we investigated the response of human neuroblastoma cell line (SH-SY5Y) to gold surfaces with different levels of nanoroughness. To achieve a precise control of the nanoroughness with nanometer resolution, we exploited a wet chemistry approach based on spontaneous galvanic displacement reaction. We demonstrated that neurons sense and actively respond to the surface nanotopography, with a surprising sensitivity to variations of few nanometers. We showed that focal adhesion complexes, which allow cellular sensing, are strongly affected by nanostructured surfaces, leading to a marked decrease in cell adhesion. Moreover, cells adherent on nanorough surfaces exhibit loss of neuron polarity, Golgi apparatus fragmentation, nuclear condensation, and actin cytoskeleton that is not functionally organized. Apoptosis/necrosis assays established that nanoscale features induce cell death by necrosis, with a trend directly related to roughness values. Finally, by seeding SH-SY5Y cells onto micropatterned flat and nanorough gold surfaces...
The self-assembly of proteins and peptides into polymeric amyloid fibrils is a process that has important implications ranging from the understanding of protein misfolding disorders to the discovery of novel nanobiomaterials. In this study, we probe the stability of fibrils prepared at pH 2.0 and composed of the protein insulin by manipulating electrostatic interactions within the fibril architecture. We demonstrate that strong electrostatic repulsion is sufficient to disrupt the hydrogen-bonded, cross-β network that links insulin molecules and ultimately results in fibril dissociation. The extent of this dissociation correlates well with predictions for colloidal models considering the net global charge of the polypeptide chain, although the kinetics of the process is regulated by the charge state of a single amino acid. We found the fibrils to be maximally stable under their formation conditions. Partial disruption of the cross-β network under conditions where the fibrils remain intact leads to a reduction in their stability. Together, these results support the contention that a major determinant of amyloid stability stems from the interactions in the structured core, and show how the control of electrostatic interactions can be used to characterize the factors that modulate fibril stability.
Nanotechnology has emerged to be one of the most powerful engineering approaches in the past half a century. Nanotechnology brought nanomaterials for biomedical use with diverse applications. In the present manuscript we summarize the recent progress in adopting nanobiomaterials for bone healing and repair approaches. We first discuss the use of nanophase surface modification in manipulating metals and ceramics for bone implantation, and then the use of polymers as nanofiber scaffolds in bone repair. Finally we briefly present the potential use of the nanoparticle delivery system as adjunct system in promoting bone regeneration following fracture.
Mechanical strength of nanofiber scaffolds formed by the self-assembling peptide RADA16-I or its derivatives is not very good and limits their application. To address this problem, we inserted spidroin uncrystalline motifs, which confer incomparable elasticity and hydrophobicity to spider silk GGAGGS or GPGGY, into the C-terminus of RADA16-I to newly design two peptides: R3 (n-RADARADARADARADA-GGAGGS-c) and R4 (n-RADARADARADARADA-GPGGY-c), and then observed the effect of these motifs on biophysical properties of the peptide. Atomic force microscopy, transmitting electron microscopy, and circular dichroism spectroscopy confirm that R3 and R4 display β-sheet structure and self-assemble into long nanofibers. Compared with R3, the β-sheet structure and nanofibers formed by R4 are more stable; they change to random coil and unordered aggregation at higher temperature. Rheology measurements indicate that novel peptides form hydrogel when induced by DMEM, and the storage modulus of R3 and R4 hydrogel is 0.5 times and 3 times higher than that of RADA16-I, respectively. Furthermore, R4 hydrogel remarkably promotes growth of liver cell L02 and liver cancer cell SMCC7721 compared with 2D culture, determined by MTT assay. Novel peptides still have potential as hydrophobic drug carriers; they can stabilize pyrene microcrystals in aqueous solution and deliver this into a lipophilic environment...
During the last decade, due to advances in functionalization chemistry, novel nanobiomaterials with applications in tissue engineering and regenerative medicine have been developed. These novel materials with their unique physical and chemical properties are bioactive hierarchical structures that hold great promise for future development of human tissues. Thus, various nanomaterials are currently being intensively explored in the directed differentiation of stem cells, the design of novel bioactive scaffolds, and new research avenues towards tissue regeneration. This paper illustrates the latest achievements in the applications of nanotechnology in tissue engineering in the field of regenerative medicine.
RNA and protein are potential molecules that can be used to construct functional nanobiomaterials. Recent findings on riboswitches emphasize on the dominative function of RNAs in regulating protein functions through allosteric interactions between RNA and protein. In this study, we demonstrate a simple strategy to obtain RNAs that have a switching ability with respect to protein function in response to specific target molecules. RNA aptamers specific for small ligands and a trans-activation-responsive (TAR)-RNA were connected by random RNA sequences. RNAs that were allosterically bound to a trans-activator of transcription (Tat)-peptide in response to ligands were selected by repeated negative and positive selection in the absence and presence of the ligands, respectively. The selected RNAs interacted with artificially engineered Renilla Luciferase, in which the Tat-peptide was inserted within the Luciferase, in the presence of the specific ligand and triggered the “Lighting-UP” switch of the engineered Luciferase.
The future of tissue engineering requires development of intelligent biomaterials using nanoparticles. Magnetic nanoparticles (MNPs) have several applications in biology and medicine; one example is Food and Drug Administration (FDA)-approved contrast agents in magnetic resonance imaging. Recently, MNPs have been encapsulated within cell-encapsulating hydrogels to create novel nanobiomaterials (i.e., M-gels), which can be manipulated and assembled in magnetic fields. The M-gels can be used as building blocks for bottom-up tissue engineering to create 3D tissue constructs. For tissue engineering applications of M-gels, it is essential to study the release of encapsulated MNPs from the hydrogel polymer network and the effect of MNPs on hydrogel properties, including mechanical characteristics, porosity, swelling behavior, and cellular response (e.g., viability, growth). Therefore, we evaluated the release of MNPs from photocrosslinkable gelatin methacrylate hydrogels as the polymer network undergoes biodegradation using inductively coupled plasma atomic emission spectroscopy. MNP release correlated linearly with hydrogel biodegradation rate with correlation factors (Pearson product moment correlation coefficient) of 0.96 ± 0.03 and 0.99 ± 0.01 for MNP concentrations of 1% and 5%...
Metastasis begins with the escape, or dissemination, of cancer cells from the primary tumor. We recently demonstrated that tumors preferentially disseminate into collagen I and not into basement membrane protein gels (Matrigel). In this study, we used synthetic polymer systems to define material properties that could induce dissemination into Matrigel. We first specifically varied rigidity by varying the crosslinking density of poly(ethylene glycol) (PEG) networks within Matrigel scaffolds. Increased microenvironmental rigidity limited epithelial growth but did not promote dissemination. We next incorporated adhesive signals into the PEG network using peptide-conjugated cyclodextrin (α-CDYRGDS) rings. The α-CDYRGDS rings threaded along the PEG polymers, enabling independent control of matrix mechanics, adhesive peptide composition, and adhesive density. Adhesive PEG networks induced dissemination of normal and malignant mammary epithelial cells at intermediate values of adhesion and rigidity. Our data reveal that microenvironmental signals can induce dissemination of normal and malignant epithelial cells without requiring the fibrillar structure of collagen I or containing collagen I-specific adhesion sequences. Finally, the nanobiomaterials and assays developed in this study are generally useful both in 3D culture of primary mammalian tissues and in the systematic evaluation of the specific role of mechanical and adhesive inputs on 3D tumor growth...
Targeted delivery systems of nanobiomaterials are necessary to be developed for the diagnosis and treatment of cancer. Nanobiomaterials can be engineered to recognize cancer-specific receptors at the cellular levels and to deliver anticancer drugs into the diseased sites. In particular, nanobiomaterial-based nanocarriers, so-called nanoplatforms, are the design of the targeted delivery systems such as liposomes, polymeric nanoparticles/micelles, nanoconjugates, norganic materials, carbon-based nanobiomaterials, and bioinspired phage system, which are based on the nanosize of 1–100 nm in diameter. In this review, the design and the application of these nanoplatforms are discussed at the cellular levels as well as in the clinics. We believe that this review can offer recent advances in the targeted delivery systems of nanobiomaterials regarding in vitro and in vivo applications and the translation of nanobiomaterials to nanomedicine in anticancer therapy.
Recently, we reported a new method to synthesize the rod-like tobacco mosaic virus (TMV) superlattice. To explore its potentials in nanolattice templating and tissue scaffolding, this work focused the viscoelasticity of the superlattice with a novel transient method via atomic force microscopy (AFM). For measuring viscoelasticity, in contrast to previous methods that assessed the oscillating response, the method proposed in this work enabled us to determine the transient response (creep or relaxation) of micro/nanobiomaterials. The mathematical model and numerical process were elaborated to extract the viscoelastic properties from the indentation data. The adhesion between the AFM tip and the sample was included in the indentation model. Through the functional equation method, the elastic solution for the indentation model was extended to the viscoelastic solution so that the time dependent force vs. displacement relation could be attained. To simplify the solving of the differential equation, a standard solid model was modified to obtain the elastic and viscoelastic components of the sample. The viscoelastic responses with different mechanical stimuli and the dynamic properties were also investigated.
Although nanotechnology has provided a rich variety of nanomaterials (1–100 nm) for in vivo medical applications, the blood compatibility of all these nanobiomaterials is still largely unexamined. Here, we report the preparation of blood-compatible carbon nanotubes (CNTs) that potentially represent the building blocks for nanodevices having in vivo applications. Activated partial thromboplastin time (APTT) and thromboelastography (TEG) studies prove that heparinization can significantly enhance the blood compatibility of nanomaterials.
This is the final published article and will be under embargo until the 11th of January 2015. It was originally published by Bioinspired, Biomimetics and Nanobiomaterials (http://www.icevirtuallibrary.com/content/journals).
Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.; The aim of this work was to prepare and analyze the degradation properties of pure PLGA, homogeneous ?-tricalcium phosphate (?-TCP)/PLGA and hydroxyapatite (HA)/PLGA composites for potential bone replacement applications. ?-TCP and HA powders were prepared in-house and 25 nominal wt% of calcium phosphate (CaP) powder was incorporated into commercially available PLGA pellets by twin screw extrusion. The degradation studies showed that pure PLGA had the fastest degradation rate followed by HA/PLGA and $\alpha$-TCP/PLGA. Overall, it was found that ?-TCP acted as a better buffering agent than HA, resulting in reduced acid group autocatalysis and hence a slower degradation rate.; Other