pinecone/core-2020-05-10-deduplication huggingface dataset:
Plasma surface modification of poly(D,L-lactic acid) as a tool to enhance protein adsorption and the attachment of different cell types

We have studied the influence of oxygen radio frequency glow discharge (RfGD) on the surface and bulk properties of poly(D,L-lactic acid) (PDLLA) and the effect of this surface modification on both protein adsorption and bone cell behavior. PDLLA films were characterized before and after plasma surface modification by water contact angle, surface energy, and adhesion tension of water as well as by scanning electron microscopy (SEM), X-ray electron spectroscopy (XPS), and Fourier transform infra-red (FTIR) spectroscopy. RfGD-films showed an increase in hydrophilicity and surface energy when compared with untreated films. Surface morphological changes were observed by SEM. Chemical analysis indicated significant differences in both atomic percentages and oxygen functional group. Protein adsorption was evaluated by combining solute depletion and spectroscopic techniques. Bovine serum albumin (BSA), fibronectin (FN), vitronectin (VN), and fetal bovine serum (FBS) were used in this study. RfGD-treated surfaces adsorbed more BSA and FN from single specie solutions than FBS that is a more complex, multi-specie solution. MG63 osteoblast-like cells and primary cultures of fetal rat calvarial (FRC) cells were used to assess both the effect of RfGD treatment and protein adsorption on cell attachment and proliferation. In the absence of preadsorbed proteins, cells could not distinguish between treated and untreated surfaces, with the exception of MG63 cells cultured for longer periods of time. In contrast, the adsorption of proteins increased the cells' preference for treated surfaces, thus indicating a crucial role for adsorbed proteins in mediating the response of osteogenic cells to the RfGD-treated PDLLA surface.Contract grant sponsors: Presidential Research Enhancement Fund (PREF), UTHSCSA, San Antonio, TX, USAContract grant sponsor: Foundation lot Science kind Technology (FCT), Portugal; contract grant number: SFRH/BD/11188/2002 and partial funding through FEDER and POCTI programsContract grant sponsor: EU funded Project HIPPOCRATES; contract grant number: NMP3-CT-2003-505758 Contract grant sponsor: European NoE EXPERTISSUES;Contract grant number: NMP3-CT-2004-500283
Development of a bioactive glass fiber reinforced starch-polycaprolactone composite

For bone regeneration and repair, combinations of different materials are often
needed. Biodegradable polymers are often combined with osteoconductive materials, such as
bioactive glass (BaG), which can also improve the mechanical properties of the composite. The
aim of this work was to develop and characterize BaG fiber reinforced starch–poly-ecaprolactone
(SPCL) composite. Sheets of SPCL (30/70 wt %) were produced using singlescrew
extrusion. They were then cut and compression-molded in layers with BaG fibers to
form composite structures with different combinations. Mechanical and degradation properties
of the composites were studied. The actual amount of BaG in the composites was
determined using combustion tests. Initial mechanical properties of the reinforced composites
were at least 50% better than the properties of the nonreinforced specimens. However, the
mechanical properties of the composites after 2 weeks of hydrolysis were comparable to those
of the nonreinforced samples. During the 6 weeks hydrolysis the mass of the composites had
decreased only by about 5%. The amount of glass in the composites remained as initial for the
6-week period of hydrolysis. In conclusion, it is possible to enhance initial mechanical
properties of SPCL by reinforcing it with BaG fibers. However, mechanical properties of the
composites are typical for bone fillers and strength properties need to be further improved for
allowing more demanding bone applications.Technology Development Center in Finland (TEKES); contract grant number: 90220.European Commission (European Union Project EXPER-TISSUES); contract grant number: NMP3-CT-2004-500328.Academy of Finland; contract grant number: 37726.The Ministry of Italian University (MIUR)-Rome, through the PRIN'06 prot. n. 2006038548 project; InterUniversity Consortium of Materials Science and Technology (INSTM), Florence, through the PRISMA'04 project
Surface AFM microscopy of unworn and worn samples of silicone hydrogel contact lenses

Abstract: Purpose. To evaluate the qualitative and quantitative topographic changes in the
surface of worn contact lenses (CLs) of different materials using atomic force microscopy (AFM). Methods. The topography of five different CL materials was evaluated withAFM over a surface of 25 lm2 according to previously published experimental setup. Average roughness (Ra) and root mean square (Rms) values were obtained for unworn and worn samples. Results. The Ra value increased for balafilcon A (11.62–13.68 nm for unworn and worn samples, respectively), lotrafilcon A (3.67–15.01 nm for unworn and worn samples, respectively),
lotrafilcon B (4.08–8.42 nm for unworn and worn samples, respectively), galyfilcon A (2.81–14.6 nm for unworn and worn samples, respectively), and comfilcon A (2.87–4.63 nm for unworn and worn samples, respectively). Differences were statistically significant for all lenses except Rms and Ra for comfilcon A, and Ra parameter for balafilcon A (p > 0.05). The least relative increase was observed for some balafilcon A samples and for some of these samples the roughness decreased after the lenses had been worn. Conclusion. The changes in surface roughness between unworn and worn lenses are different for different silicone-hydrogel materials. Overall all CLs increased the degree of surface roughness after being worn, even for very short periods of time. However, for samples of balafilcon A, roughness increases at a lower extent or even can decrease as compared to unworn samples of the same material due to filling of the macropores.Fundação para a Ciência e a Tecnologia (FCT)Ministério da Ciência e Ensino Superior (MCES)Fundo Social Europeu  - contrato nº  8281/2002
In vitro toxicity of filler particles and methacrylates used in dental composite materials. Cytokine release and cell death

<p>Dental polymer-based composite materials are complex materials consisting of several
components, the main components being filler particles (inorganic component) and
polymer matrix (organic component). The organic component consists of monomers
that usually are polymerized upon activation by visible light illumination.</p><p>The polymerization process is never complete, and leakage of unreacted methacrylate
monomers occurs during clinical service. Degradation processes may weaken the bond
between the fillers and the matrix, leading to release of fillers particles and ions in
addition to the organic components. Clinical handling during placement and finishing
has been shown to cause release of particulate matter to the air in dental clinics, which
could be followed by exposure to tissue and saliva of the patients. Thus, both dental
personnel and patients could be exposed to components of polymer-based dental
materials.</p><p>The main objective of the thesis was to characterize the toxic potential of selected
inorganic filler particles (barium glass particles and silica particles) and methacrylates
(HEMA, TEGDMA, BisGMA, GDMA, MMA) used in dental composite filling
materials. The results showed that both nano- and micro-sized filler particles could
modulate the release of inflammatory mediators in vitro. The methacrylates
investigated induced cytotoxicity, but the potency and the mechanism involved
seemed to differ between the methacrylates. HEMA was found to induce apoptosis
and DNA damage followed by activation of DNA damage response. To address
possible exposure to multiple components of polymer-based dental composite
materials the effect of co-exposure to components was studied. An additive
inflammatory response was observed with particles and TEGDMA co-exposure.</p><p>Studies on the mechanisms of possible adverse biological responses to substances
released from polymer-based dental materials could contribute to safer dental materials.</p
High Resolution 1H NMR investigations of the capacity of dentrifices containing a smart bioactive glass to influence the metabolic profile of and deliver calcium ions to human saliva.

Dentifrices containing H2O-reactive bioactive glasses alleviate hypersensitivity in\ud
teeth via the blockage of open dentinal tubules. Here, the ability of two such products to\ud
release Ca21 ions into human saliva was investigated, together with their influence on the\ud
status of this biofluid’s 1H NMR-detectable biomolecules. Human salivary supernatants were equilibrated with increasing volumes of those derived from each dentifrice (5.00 min at 378C).These biofluids were also equilibrated at 378C with a preselected quantity of the intact products (samples were collected at increasing timepoints). Salivary Ca21 concentrations were monitored by a 1H NMR technique involving ethylenediamine tetra-acetate addition and/or atomic absorption spectrometry. Added Ca21- and dentifrice supernatant volume (DSV)- induced modifications to the salivary 1H NMR profile were explored by spectral titration. Data acquired demonstrated added DSV-dependent increases in salivary Ca21 concentrations and (Ca21-independent) modifications to the intensities of selected salivary 1H NMR signals, particularly those of the malodorous amines methyl-, dimethyl-, and trimethylamines, which were diminished by up to 80% of their prior values. Time-dependent elevations in salivary Ca21 level were observed on equilibration with the intact dentifrices. Added Ca21 ions exerted a concentration-dependent influence on a range of resonances (including those of citrate, succinate, pyruvate, and lactate). These data provide valuable information regarding the mechanisms of action of the products tested
Biomimetic apatite deposition on polymeric microspheres treated with a calcium silicate solution

Bioactive polymeric microspheres can be prepared by means of coating them with a calcium silicate solution and subsequently soaking in a simulated body fluid (SBF). Such combination should allow for the development of bioactive microspheres for several applications in the medical field including tissue engineering carriers. Four types of polymeric microspheres, with different sizes, were used in this work: (i) ethylene-vinyl alcohol copolymer (20–30 µm), (ii) polyamide 12 with 10% magnetite (100 µm), (iii) polyamide 12 (10–30 µm) and (iv) polyamide 12 (300 µm). These microspheres were soaked in a calcium silicate solution at 36.58C for various periods of time under different conditions. Afterwards, they were dried in air at 60 and 100ºC for 24 hr. Then, the samples were soaked in SBF for 1, 3, and 7 days. Fourier transformed infrared spectroscopy, thin-film X-ray diffraction, and scanning electron microscopy showed that after the calcium silicate treatment and the subsequent soaking in SBF, the microspheres successfully formed an apatite layer on their surfaces in SBF within 7 days due to the formation of silanol groups, which are effective for apatite formation.Contract grant sponsor: European NoE EXPERTISSUES; Contract grant number: NMP3-CT-2004-50028
Proliferation and differentiation of goat bone marrow stromal cells in 3d scaffolds with tunable hydrophilicity

We have synthesized methacrylate-endcapped caprolactone networks with tailored
water sorption ability, poly(CLMA-co-HEA), in the form of three-dimensional (3D) scaffolds
with the same architecture but exhibiting different hydrophilicity character (xHEA50, 0.3, 0.5),
and we investigated the interaction of goat bone marrow stromal cells (GBMSCs) with such
structures. For this purpose, GBMSCs were seeded and cultured for 3, 7, 14, 21, and 28 days
onto the developed scaffolds. Cells have proliferated throughout the whole scaffold volume.
Cell adhesion and morphology were analyzed by SEM, whereas cell viability and proliferation
was assessed by MTS test and DNA quantification concluding that numbers of cells increased
as a function of the culturing time (until day 14) and also with the hydrophobic content in the
samples (from 50 to 100% of CLMA). No significant difference between samples with 100%
and 70% of CLMA were detected in some cases. Osteoblastic differentiation was followed by
assessing the alkaline phosphatase activity of cells, as well as type I collagen and osteocalcin
expressions levels until day 21. The three markers were positive at days 14 and 21 when cells
were cultured in 100% CLMA substrates which suggests osteoblastic differentiation of
mesenchymal stem cells within these scaffolds. On the other hand, when the CLMA content
decreases (until 50%), type I collagen and osteocalcin were positive but ALP was negative
indicating that the differentiation process is affected by hydrophilic content. We suggest that
such system may be useful to extract information on the effect of materials’ wettability on the
corresponding biological performance in a 3D environment. Such general insights may be
relevant in the context of biomaterials selection for tissue engineering strategies.Contract grant sponsor: Spanish Ministry of Science Contract grant number: MAT2007-66759-C03-0
Adsorption and release of BMP-2 on nanocrystalline apatite-coated and uncoated hydroxyapatite/b-tricalcium phosphate porous ceramics

The association of bone morphogenetic proteins (BMPs) with calcium phosphate bioceramics is known to confer them osteoinductive properties. The aim of this study was to\ud
evaluate the surface properties, especially regarding recombinant human BMP-2 (rhBMP-2) adsorption and release, of commercial sintered biphasic calcium phosphate ceramics after coating with biomimetic nanocrystalline apatite. The raw and coated ceramics exhibited similar macroporous structures but different nanometer-sized pores contents. Both types of ceramics showed Langmuir-type adsorption isotherms of rhBMP-2. The coating noticeably increased the rate of adsorption and the total amount of growth factor taken up, but the maximum coverage per surface area unit as well as the affinity constant appeared lower for coated ceramics compared with raw ceramic surfaces. The limited advantage gained by coating the ceramics can be assigned to a lower accessibility of the surface adsorption sites\ud
compared with the raw ceramics. The quantity of rhBMP-2 spontaneously released in cell culture medium during the first weeks was lower for coated samples than for uncoated\ud
ceramics and represented a minor fraction of the total adsorbed amount. In conclusion, the nanocrystalline apatite coating was found to favor the adsorption of rhBMP-2 while providing a mean to fine tune the release of the growth factor
Biomimetic Ca-P coatings Incorporating bisphosphonates produced on starch-based degradable biomaterials

In this study, sodium clodronate, a well-known therapeutic agent from the family
of bisphosphonates (BPs), is incorporated in a biomimetic calcium phosphate (CaP) coating,
previously formed on the surface of a starch-based biomaterial by a sodium silicate
methodology, as a strategy to develop a site-specific drug delivery system for bone tissue
regeneration applications. The effects on the resulting CaP coatings were evaluated in terms of
morphology, chemistry, and structure. The dissolution of Ca and P from the coating and the
release profiles of sodium clodronate was also assessed. As a preliminary approach, this first
study also aimed at evaluating the effects of this BP on the viability of a human osteoblastic
cell line since there is still little information available on the interaction between BPs and this
type of cells. Sodium clodronate was successfully incorporated, at different doses, in the
structure of a biomimetic CaP layer previously formed by a sodium silicate process. This
type of BPs had a stimulatory effect on osteoblastic activity, particularly at the specific
concentration of 0.32 mg/mL. It is foreseen that these coatings can, for instances, be
produced on the surface of degradable polymers and then used for regulating the
equilibrium on osteoblastic/osteoclastic activity, leading to a controlled regenerative effect
at the interface between the biomaterial and bone
Bioactive inorganic materials/alginate composite microspheres with controllable drug-delivery ability

Alginate microspheres are considered a promising material as a drug carrier in bone repair due to excellent biocompatibility, but their main disadvantage is low drug entrapment efficiency and non-controllable release.  The aim of this study was to investigate the effect of incorporating mesoporous bioglass (MBG), non-mesoporous bioglass (BG) or hydroxyapatite (HAp) into alginate microspheres on their drug-loading and release properties.  X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and atomic emission spectroscopy (AES) were used to analyse the composition, structure and dissolution of bioactive inorganic materials and their microspheres.  Dexamethasone (DEX)-loading and release ability of four microspheres were tested in phosphate buffered saline with varying pHs.  Results showed that the drug-loading capacity was enhanced with the incorporation of bioactive inorganic materials into alginate microspheres.  The MBG/Alginate microspheres had the highest drug loading ability.  DEX release from alginate microspheres correlated to the dissolution of MBG, BG and HAp in PBS, and that the pH was an efficient factor in controlling the DEX release; a high pH resulted in greater DEX release, whereas a low pH delayed DEX release.  In addition, MBG/alginate, BG/alginate and HAp/alginate microspheres had varying apatite-formation and dissolution abilities, which indicate that the composites would behave differently with respect to bioactivity.  The study suggests that microspheres made of a composite of bioactive inorganic materials and alginate have a bioactivity and degradation profile which greatly improves their drug delivery capacity, thus enhancing their potential applications as bioactive filler materials for bone tissue regeneration
Nanosized hydroxyapatite and other calcium phosphates: Chemistry of formation and application as drug and gene delivery agents

The first part of this review looks at the fundamental properties of hydroxyapatite (HAP), the basic mineral constituent of mammalian hard tissues, including the physicochemical features that govern its formation by precipitation. A special emphasis is placed on the analysis of qualities of different methods of synthesis and of the phase transformations intrinsic to the formation of HAP following precipitation from aqueous solutions. This serves as an introduction to the second part and the main subject of this review, which relates to the discourse regarding the prospects of fabrication of ultrafine, nanosized particles based on calcium phosphate carriers with various therapeutic and/or diagnostic agents coated on and/or encapsulated within the particles. It is said that the particles could be either surface-functionalized with amphiphiles, peptides, proteins, or nucleic acids or injected with therapeutic agents, magnetic ions, or fluorescent molecules. Depending on the additive, they could be subsequently used for a variety of applications, including the controlled delivery and release of therapeutic agents (extracellularly or intracellularly), magnetic resonance imaging and hyperthermia therapy, cell separation, blood detoxification, peptide or oligonucleotide chromatography and ultrasensitive detection of biomolecules, and in vivo and in vitro gene transfection. Calcium phosphate nanoparticles as carriers of therapeutic agents that would enable a controlled drug release to treat a given bone infection and at the same be resorbed in the body so as to regenerate hard tissue lost to disease are emphasized hereby as one of the potentially attractive smart materials for the modern medicine. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011
In vitro biodegradation behavior of magnesium and magnesium alloy

Magnesium has the potential to be used as degradable
metallic biomaterial. For magnesium and its alloys to be
used as biodegradable implant materials, their degradation
rates should be consistent with the rate of healing of the
affected tissue, and the release of the degradation products
should be within the body’s acceptable absorption levels.
Conventional magnesium degrades rapidly, which is undesirable.
In this study, biodegradation behaviors of high purity
magnesium and commercial purity magnesium alloy AZ31 in
both static and dynamic Hank’s solution are systematically
investigated. The in vitro test results show that magnesium
purification and selective alloying are effective approaches to reduce the degradation rate of magnesium. In the static condition, the corrosion products accumulate on the materials surface as a protective layer, which results in a lower degradation rate than the dynamic condition. Anodized coating can significantly further reduce the degradation rate of magnesium. This study strongly indicates that magnesium can be used as degradable implant material as long as the degradation is controlled at a low rate. Magnesium purification, selective alloying, and anodized coating are three effective approaches to reduce the rate of degradation.
The effects of bioactive akermanite on physiochemical, drug-delivery and biological properties of poly (lactide-co-glycolide) beads

Poly(lactide-co-glycolide) (PLGA) beads have been widely studied as a potential drug/protein carrier. The main shortcomings of PLGA beads are that they lack bioactivity and controllable drug-delivery ability, and their acidic degradation by-products can lead to pH decrease in the vicinity of the implants. Akermanite (AK) (Ca(2) MgSi(2) O(7) ) is a novel bioactive ceramic which has shown excellent bioactivity and degradation in vivo. This study aimed to incorporate AK to PLGA beads to improve the physiochemical, drug-delivery, and biological properties of PLGA beads. The microstructure of beads was characterized by SEM. The effect of AK incorporating into PLGA beads on the mechanical strength, apatite-formation ability, the loading and release of BSA, and the proliferation, and differentiation of bone marrow stromal cells (BMSCs) was investigated. The results showed that the incorporation of AK into PLGA beads altered the anisotropic microporous structure into homogenous one and improved their compressive strength and apatite-formation ability in simulated body fluids (SBF). AK neutralized the acidic products from PLGA beads, leading to stable pH value of 7.4 in biological environment. AK led to a sustainable and controllable release of bovine serum albumin (BSA) in PLGA beads. The incorporation of AK into PLGA beads enhanced the proliferation and alkaline phosphatase activity of BMSCs. This study implies that the incorporation of AK into PLGA beads is a promising method to enhance their physiochemical and biological property. AK/PLGA composite beads are a potential bioactive drug-delivery system for bone tissue repair