Search

Introduction Silver decorated mesoporous carbons are interesting systems that may offer effective solutions for advanced wound care products by combining the well-known anti-microbial activity of silver nanoparticles with the versatile properties of ordered mesoporous carbons. Silver is being used as a topical antimicrobial agent, especially in wound repair. However, while silver shows bactericidal properties, it is also cytotoxic at high concentrations. Therefore, the incorporation of silver into ordered mesoporous carbons allows to exploit both silver's biological effects and mesoporous carbons' biocompatibility and versatility with the purpose of conceiving silver-doped materials in light of the growing health concern in wound care. Methods The wound healing potential of an ordered mesoporous carbon also doped with two different loadings of silver nanoparticles (2 wt% and 10 wt%), was investigated through a biological assessment study based on different assays (cell viability, inflammation, antibacterial tests, macrophage-conditioned fibroblast and human keratinocyte cell cultures). Results The results show silver-doped ordered mesoporous carbons to positively condition cell viability, with a cell viability percentage >70% even for 10 wt% Ag, to modulate the expression of inflammatory cytokines and of genes involved in tissue repair (KRT6a, VEGFA, IVN) and remodeling (MMP9, TIMP3) in different cell systems. Furthermore, along with the biocompatibility and the bioactivity, the silver-doped ordered mesoporous carbons still retain an antibacterial effect, as shown by a maximum of 13.1% of inhibited area in the Halo test. The obtained results clearly showed that the silver-doped ordered mesoporous carbons exhibit both good biocompatibility and antibacterial effect with enhanced re-epithelialization, angiogenesis promotion and tissue regeneration. Discussion These findings suggest that the exceptional properties of silver-doped ordered mesoporous carbons could be exploited in the treatment of acute and chronic wounds and that such carbon materials could be potential candidates for use in medical devices for wound healing purposes, in particular, the 10 wt% loading, as the results showed to be the most effective.

Mesoporous silica- and carbon-based materials, including bioactive glasses, have proven potential as components of medical devices and as drug carriers. From an application perspective, knowledge about the shelf-life stability of these materials under various conditions is vital. Here, mesoporous bioactive glasses (MBGs) synthesized by aerosol-assisted spray-drying and by a batch sol-gel method, mesoporous silicas of SBA-15 type, and mesoporous carbons CMK-1 and CMK-3 have been stored under varying conditions, e.g. at different temperature and relative humidity (RH), and in different storage vessels. The results show that the silica-based materials stored in Eppendorfs are sensitive to humidity. Spray dried MBGs decompose within 1 month at a RH >5%, whilst sol-gel MBGs are more stable up to a RH >60%. Changing the storage vessel to sealed glass flasks increases the MBGs lifetime significantly, with no degradation during 2 months of storage at a RH = 75%. SBA-15 stored in Eppendorfs are more stable compared to MBGs, and addition of F- ions added during the synthesis affects the material degradation rate. Mesoporous carbons are stable under all conditions for all time points. This systematic study clearly demonstrates the importance of storage conditions for mesoporous materials which is crucial knowledge for commercialization of these materials. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry. Funding Agencies|European UnionEuropean Commission [685872]

[EN] The purpose of this study was to evaluate the local biological effects and bone regeneration efficacy of a polyphenols-enriched ceramic bone filler. To this end, a test article (NBR_Purple) a biphasic phosphate ceramic plus polyphenols from grape pomace and the same material without polypohenols (NBR_White), were implanted in the medial condyle of the femur bone of rabbits for 56 days. A control article of clinical use (Ostim ®), was implanted as the first control condition. There was a second control by performing the same defect at the same location but without any implanted material (void condition). Histological examination at the end of the test period shows statistically significant improvement of bone regeneration by the polyphenolenriched material over the same material without polyphenols, supporting literature data on the involvement of polyphenol molecules in bone regeneration pathways.

In the present study, the cytotoxicity and the antimicrobial activity of two silver citrate-based irrigant solutions were investigated. Cytotoxicity of various concentrations (0.25%, 0.5%, 1%, 2.5%, 5%) of both solutions (BioAKT and BioAKT Endo) was assessed on L929 mouse fibroblasts using the MTT assay. For the quantitative analysis of components, an infrared (I.R.) spectroscopy was performed. The minimum inhibitory and minimal bactericidal concentrations (M.I.C. and M.B.C., respectively) were ascertained on Enterococcus faecalis strain ATCC 4083. For biofilm susceptibility after treatment with the irrigating agent, a minimum biofilm eradication concentration (M.B.E.C.) and confocal laser scanning microscope (C.L.S.M.) assays were performed. Quantification of E. faecalis cell biomass and percentage of live and dead cells in the biomass was appraised. Normality of data was analyzed using the D&rsquo, Agostino &amp, Pearson&rsquo, s test and the Shapiro&ndash, Wilk test. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey&rsquo, s test. Both silver citrate solutions showed mouse fibroblasts viability &gt, 70% when diluted to 0.25% and 0.5%. Conversely, at higher concentrations, they were extremely cytotoxic. F.T.IR spectroscopy measurements of both liquids showed the same spectra, indicating similar chemical characteristics. No substantial contrast in antimicrobial activity was observed among the two silver citrate solutions by using broth microdilution methods, biofilm susceptibility (MBECHTP device), and biomass screening using confocal laser scanning microscopy (C.L.S.M.) technique. Both solutions, used as root canal irrigants, exhibited significant antimicrobial activity and low cytocompatibility at dilutions greater than 0.5%.

Polyphenols are increasingly investigated for the treatment of periodontitis and research on their use in dental biomaterials is currently being conducted. Grape pomace extracts are a rich source of polyphenols. In the present study, the polyphenols of two different types of grape pomace were characterized and identified by high‑performance liquid chromatography‑diode array detector, and the effect of polyphenol‑rich grape pomace extracts on mesenchymal stem cell (MSC) osteogenic differentiation was investigated. Solid‑liquid extraction was used to recover polyphenols from red and white grape pomace. The two extracts have been characterized through the phenolic content and antioxidant power. Human MSCs (hMSCs) from the bone marrow were cultured both with and without given amounts (10 or 20 µg/ml) of the obtained pomace extracts. Their effects on cell differentiation were evaluated by reverse transcription‑quantitative polymerase chain reaction, compared with relevant controls. Results showed that both pomace extracts, albeit different in phenolic composition and concentration, induced multiple effects on hMSC gene expression, such as a decreased receptor activator of nuclear factor κ‑Β ligand/osteoprotegerin ratio and an enhanced expression of genes involved in osteoblast differentiation, thus suggesting a shift of hMSCs towards osteoblast differentiation. The obtained results provided data in favor of the exploitation of polyphenol properties from grape pomace extracts as complementary active molecules for dental materials and devices for bone regeneration in periodontal defects.

The objectives of this study are to evaluate long‐term wettability of novel surface‐engineered, clinically available dental implants, featuring a surface nanolayer of covalently linked hyaluronan, and to confirm the relationships between wetting properties and surface nanostructure and microstructure. Wettability measurements were performed on clinically available hyaluronan‐coated Grade 4 titanium implants, packaged and sterile, that is, in the “on the shelf” condition, after 1 year from production. Wetting properties were measured by the Wilhelmy plate method. Analysis of the surface structure and chemistry was perfomed by X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy‐dispersive X‐ray (EDX) analysis, atomic force microscopy (AFM), and ζ‐potential measurement, either on implants or disks or plates subjected to the same surface‐engineering process. Results show that hydrophilicity and ensuing capillary rise of the hyaluronan‐coated implant surface is unaffected by aging and dry storage. Chemical analysis of the implant surface by XPS and evaluation of the ζ potential indicate that hyaluronan chemistry and not that of titanium dictates interfacial properties. Comparison between XPS versus EDX and SEM versus AFM data confirm that the thickness of the hyaluronan surface layer is within the nanometer range. Data show that nanoengineering of the implant surface by linking of the hydrophilic hyaluronan molecule endows tested titanium implants by permanent wettability, without need of wet storage as presently performed to keep long‐term hydrophilic implant surfaces. From an analytical point of view, the introduction in routine clinical practice of nanoengineered implant surfaces requires upgrading of analytical methods to the nanoscale.

To achieve optimal performances, guided bone regeneration membranes should have several properties, in particular, proper stiffness and tear resistance for space maintenance, appropriate resorption time, and non-cytotoxic effect. In this work, polyphenol-rich pomace extract (PRPE), from a selected grape variety (Nebbiolo), rich in proanthocyanidins and flavonols (e.g., quercetin), was used as a rich source of polyphenols, natural collagen crosslinkers, to improve the physical properties of the porcine pericardium membrane. The incorporation of polyphenols in the collagen network of the membrane was clearly identified by infra-red spectroscopy through the presence of a specific peak between 1360&ndash, 1380 cm&minus, 1. Polyphenols incorporated into the pericardium membrane bind to collagen with high affinity and reduce enzymatic degradation by 20% compared to the native pericardium. The release study shows a release of active molecules from the membrane, suggesting a possible use in patients affected by periodontitis, considering the role of polyphenols in the control of this pathology. Mechanical stiffness is increased making the membrane easier to handle. Young&rsquo, s modulus of pericardium treated with PRPE was three-fold higher than the one measured on native pericardium. Tear and suture retention strength measurement suggest favorable properties in the light of clinical practice requirements.

The osseointegration of dental implants and their consequent long-term success is guaranteed by the presence, in the extraction site, of healthy and sufficient alveolar bone. Bone deficiencies may be the result of extraction traumas, periodontal disease and infection. In these cases, placement of titanium implants is contraindicated until a vertical bone augmentation is obtained. This goal is achieved using bone graft materials, which should simulate extracellular matrix (ECM), in order to promote osteoblast proliferation and fill the void, maintaining the space without collapsing until the new bone is formed. In this work, we design, develop and characterize a novel, moldable chitosan-pectin hydrogel reinforced by biphasic calcium phosphate particles with size in the range of 100–300 μm. The polysaccharide nature of the hydrogel mimics the ECM of natural bone, and the ceramic particles promote high osteoblast proliferation, assessed by Scanning Electron Microscopy analysis. Swelling properties allow significant adsorption of water solution (up to 200% of solution content) so that the bone defect space can be filled by the material in an in vivo scenario. The incorporation of ceramic particles makes the material stable at different pH and increases the compressive elastic modulus, toughness and ultimate tensile strength. Furthermore, cell studies with SAOS-2 human osteoblastic cell line show high cell proliferation and adhesion already after 72 h, and the presence of ceramic particles increases the expression of alkaline phosphatase activity after 1 week. These results suggest a great potential of the developed moldable biomaterials for the regeneration of the alveolar bone. Statement of Significance The positive fate of a surgical procedure involving the insertion of a titanium screw still depends on the quality and quantity of alveolar bone which is present in the extraction site. Available materials are basically hard scaffold materials with un-predictable behavior in different condition and difficult shaping properties. In this work we developed a novel pectin-chitosan hydrogel reinforced with ceramic particles. Polysaccharides simulate the extracellular matrix of natural bone and the extensive in vitro cells culture study allows to assess that the incorporation of the ceramic particles promote a pro-osteogenic response. Shape control, easy adaption of the extraction site, predictable behavior in different environment condition, swelling properties and an anti-inflammatory response are the significant characteristics of the developed biomaterial.

This case report provided a unique opportunity to investigate the extent of microbiota infiltration on the oxidized implant surface that has been compromised by peri-implantitis. Scanning electron microscopic analysis confirmed the etiologic role of the bacteria on the loss of supporting structure and the difficulty in complete removal of bacterial infiltration on the implant surface. This case report emphasizes the need to perform definitive surface decontamination on failing dental implants prior to a regeneration procedure.

Mesoporous bioactive glass nanoparticles (MBG) are multifunctional building blocks for tissue regeneration and nanomedicine applications. Incorporation of biologically active ions can endow MBG with additional functionalities toward promoted therapeutic effects. Here, boron is incorporated into MBG by using a sol–gel approach. The concentration of boron incorporated is controllable by tuning the amount of boron precursor. Two types of boron‐doped MBG, namely 10B‐ and 15B‐MBG (5.8 and 6.5 mol% of B2O3, respectively) are synthesized. Boron incorporation does not significantly influence the particle morphology. All synthesized particles exhibit a sphere‐like shape with a size ranging from 100 to 300 nm. 10B‐ and 15B‐MBG show large specific surface area (346 and 320 m² g−1, respectively) and pore volume. Both boron‐doped MBG exhibit remarkable in vitro bioactivity and noncytotoxicity. Boron incorporation is shown to reduce the inflammatory response linked to macrophages as indicated by downregulated expression of pro‐inflammatory genes. However, boron incorporation delays the osteogenic differentiation in osteoblasts as indicated by the downregulated expression of pro‐osteogenic genes. The results demonstrate the promising potential of using boron‐doped MBG to modulate inflammatory response for bone regeneration under inflammatory conditions, as shown in this study for the first time.

Biochemical modification of titanium surfaces (BMTiS) entails immobilization of biomolecules to implant surfaces in order to induce specific host responses. This crossover randomized clinical trial assesses clinical success and marginal bone resorption of dental implants bearing a surface molecular layer of covalently-linked hyaluronan in comparison with control implants up to 36 months after loading. Patients requiring bilateral implant rehabilitation received hyaluronan covered implants in one side of the mouth and traditional implants in the other side. Two months after the first surgery, a second surgery was undergone to uncover the screw and to place a healing abutment. After two weeks, the operator proceeded with prosthetic procedures. Implants were evaluated by periapical radiographs and the crestal bone level was recorded at mesial and distal sites&mdash, at baseline and up to 36 months. One hundred and six implants were positioned, 52 HY-coated, and 48 controls were followed up. No differences were observed in terms of insertion and stability, wound healing, implant success, and crestal bone resorption at any time considered. All interventions had an optimal healing, and no adverse events were recorded. This trial shows, for the first time, a successful use in humans of biochemical-modified implants in routine clinical practice and in healthy patients and tissues with satisfactory outcomes.

The purpose of this paper is to describe an innovative treatment for titanium dental implants, aimed at faster and more effective osteointegration. The treatment has been performed with the use of hydrogen peroxide, whose action was enhanced by concomitant exposure to a source of ultraviolet light. The developed surface oxide layer was characterized from the physical and chemical points of view. Moreover osteoblast-like SaOS2 cells were cultured on treated and control titanium surfaces and cell behavior investigated by scanning electron microscope observation and gene expression measurements. The described process produces, in only 6 min, a thin, homogeneous, not porous, free of cracks and bioactive (in vitro apatite precipitation) oxide layer. High cell density, peculiar morphology and overexpression of several genes involved with osteogenesis have been observed on modified surfaces. The proposed process significantly improves the biological response of titanium surfaces, and is an interesting solution for the improvement of bone integration of dental implants. A clinical application of the described surfaces, with a 5 years follow-up, is reported in the paper, as an example of the effectiveness of the proposed treatment.

To investigate the effects of titanium implants functionalised with collagen type I (TiColl) on bone regeneration and osteointegration in a healthy and osteopenic rat animal model. TiColl screws were implanted into the femoral condyles of healthy and osteopenic rats and compared with acid-etched titanium (Ti) screws. The osteointegration process was evaluated by a complementary approach combining microtomographic, histological, histomorphometric and biomechanical investigations at four and 12 weeks. The TiColl screw also ensured a greater mechanical stability; the push-out values for TiColl screws increased from four to 12 weeks (+28 %). The energy necessary to detach the bone from the screw was significantly higher for TiColl-functionalised screws in comparison to Ti screws (+23 %) at 12 weeks. Histomorphometric investigation revealed that total bone-to-implant contact was higher in TiColl screws in comparison to Ti screws (P

Bioglass® type 45S5 is the most widespread bioactive glass studied for its inorganic bioactivity and ability to affect cell behaviour. In this research work sintered Bioglass® substrates were functionalized with a biological molecule (the enzyme alkaline phosphatase — ALP) in order to couple bioactive glass typical inorganic properties with biological signals. For the first time ALP grafting has been performed on the standard Bioglass® composition, which is the most widely bioactive glass studied and currently commercialized in various forms. ALP was grafted to sintered Bioglass® glass–ceramic pellets both via silanization and via direct bonding to hydroxyl groups exposed on the surface. The presence of the biomolecule was investigated by means of XPS and its activity by enzymatic activity test. In vitro bioactivity of sintered Bioglass® at different steps of the functionalization process was investigated by soaking samples in simulated body fluid (SBF) for various experimental times. The possibility to graft ALP in an active state on sintered Bioglass® samples both via direct grafting and silanization routes has been demonstrated in the present research. ALP enhances and fastens in vitro bioactivity of the glass–ceramic. Surface functionalization of Bioglass® pellets is of interest as model for sintered Bioglass® derived scaffolds to be used in bone engineering.

Titanium and its alloys are the most widespread materials for the realization of orthopaedic and dental implants due to their good mechanical properties and biocompatibility. Surface functionalization of biomaterials aimed to improve and quicken implant integration and tissue regeneration is an active research field. The opportunity to confer biological activity (ability to directly stimulate cells with proper biological signals) to the Ti6Al4 V alloy, previously modified to be bioactive from the inorganic point of view (apatite precipitation), was explored in this research work. The alkaline phosphatase (ALP) enzyme was grafted to metal surface via tresyl chloride activation, maintaining its activity. A synergistic effect between biological functionalization and inorganic bioactivity was observed.

The goal of this study was the in vivo evaluation of nanoporous titanium (Ti) implants bearing a covalently linked surface hyaluronan (HA) layer. Implant surface topography and surface chemistry were previously evaluated by scanning electron micorscopy and X-ray photoelectron spectroscopy. Results showed that the surface modification process did not affect surface topography, yielding a homogeneously HA-coated nanotextured implant surface. In vivo evaluation of implants in both cortical and trabecular bone of rabbit femurs showed a significant improvement of both bone-to-implant contact and bone ingrowth at HA-bearing implant interfaces at 4 weeks. The improvement in osteointegration rate was particularly evident in the marrow-rich trabecular bone (bone-to-implant contact: control 22.5%; HA-coated 69.0%, p

The goal of the present work was to investigate the relationship betweenin vivohealing and inflammatory response andin vitrocytokine expression by macrophages of a synthetic bone filler (25% hydroxylapatite-75%β-tricalcium phosphate) bearing a surface nanolayer of collagen. A clinically accepted, state-of-the-art xenograft material was used as a “negative control,” that is, as a material that provides the correct clinical response for the intended use.In vitrodata show that both materials exert a very low stimulation of proinflammatory cytokines by macrophages, and this was confirmed by the very mild inflammatory response detected inin vivotests of local response in a rabbit model. Also,in vitrofindings suggest a different mechanism of healing for the test and the control material, with a higher regenerative activity for the synthetic, resorbable filler, as confirmed byin vivoobservation and literature reports. Thus, the simplein vitromodel adopted provides a reasonable forecast ofin vivoresults, suggesting that new product development can be guided byin vitrotuning of cell-materials interactions.

The objects of this research are commercially pure titanium surfaces, with multifunctional behavior, obtained through a chemical treatment and biological functionalization. The explored surfaces are of interest for dental implants, in contact with bone, where several simultaneous and synergistic actions are needed, in order to get a fast and effective osseointegration. The here described modified surfaces present a layer of titanium oxide, thicker than the native one, with a multi-scale surface topography (a surface roughness on the nano scale, which can be overlapped to a micro or macro roughness of the substrate) and a high density of OH groups, that increase surface wettability, induce a bioactive behavior (hydroxyapatite precipitation in simulated body fluid) and make possible the grafting of biomolecules (alkaline phosphatase, ALP, in the present research). The surface oxide is an efficient barrier against corrosion, with passive behavior both with and without application of an external voltage.

Two different glasses, one biocompatible but with a low bioactivity index (G1) and the other with an higher bioactivity index (G2), the ceramic version of the second glass and a titanium alloy (Ti6Al4V) have been functionalizated by anchoring alkaline phosphatase (ALP) on their surfaces. The enzyme has been chosen because it is involved in mineralization processes of hard tissues and is a model for more complex ones. ALP has been grafted on glasses and glass-ceramics surfaces both with and without samples silanization and on metallic surfaces with and without tresyl chloride activation. Samples have been analyzed at each step of the functionalization process in order to verify it.

The paper presents results of physico-chemical and biological investigations of a surface-engineered synthetic bone filler. Surface analysis confirms that the ceramic phosphate granules present a collagen nanolayer to the surrounding environment. Cell cultures tests show that, in agreement with literature reports, surface-immobilized collagen molecular cues can stimulate progression along the osteogenic pathway of undifferentiated human mesenchymal cells. Finally, in vivo test in a rabbit model of critical bone defects shows statistically significant increase of bone volume and mineral apposition rate between the biomimetic bone filler and collagen-free control. All together, obtained data confirm that biomolecular surface engineering can upgrade the properties of implant device, by promoting more specific and targeted implant-host cells interactions.

BACKGROUND: The aim of this study was to analyze the effects of erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser and ultrasonic treatment on fibroblast attachment to periodontally diseased root surfaces. METHODS: Thirty single-rooted human periodontally involved teeth were included in this study. A total of 60 specimens were obtained from all selected teeth and were randomly assigned to the following three groups: group A, untreated control group; group B, ultrasonic group; and group C, Er:YAG laser at 160 mJ/pulse at 10 Hz group. All of the specimens were incubated in petri dishes with fibroblast suspension and observed by scanning electron microscopy. RESULTS: Laser-treated specimens showed a significantly higher cell density number, with a mean+/-SD of 3,720+/-316 cells/mm2. The ultrasonically treated group showed a lower cell density number, with a mean+/-SD of 658+/-140 cells/mm2. The untreated control group showed the lowest cell density number, with a mean+/-SD of 130+/-80 cells/mm2. Differences between all groups were significant (P

Two different cationic antimicrobial molecules, chlorhexidine (CH) and poly(hexamethylenebiguanide) (PH), were adsorbed from aqueous solution to titanium implant devices surface-modified by the covalent coupling of collagen on a polyanionic acrylic acid overlayer. Results show that more antimicrobial was adsorbed on surface modified implants as compared to control titanium devices. Moreover, the kinetic of release was affected by the interaction between the polyanionic overlayer and the cationic antimicrobial, leading to slower kinetic of release in the case of CH and stable adsorption in the case of polycationic PH . These data indicate that biochemically modified collagen coated surfaces could be endowed also by antimicrobial properties, in the spirit of present researches on multifunctional implant surfaces.

Collagen was covalently linked to the surface of Titanium (Ti) by a surface modification process involving deposition of a thin film from hydrocarbon plasma followed by acrylic acid grafting. The composition and properties of surface-modified Ti were investigated by a number of surface sensitive techniques: XPS, ATR-IR, atomic force microscopy and AFM force-separation curves. In vitro tests were performed to check samples cytotoxicity and the behavior of osteoblast-like SaOS-2 cells. In vivo experiments involved 12 weeks implants in rabbit muscle as general biocompatibility assessment and 1-month implants in rabbit bone to evaluate the effect of surface modification on osteointegration rate. Results of XPS measurements show how surface chemistry is affected throughout each step of the surface modification process, finally leading to a complete and homogeneous collagen overlayer on top of the Ti samples. AFM data clearly display the modification of the surface topography and of the surface area of the samples as a consequence of the grafting and coupling process. AFM force-distance curves show that the interfacial structure responds by shrinking or swelling to variations of ionic force of the surrounding aqueous environment, suggesting that the aqueous interface of the biochemically modified Ti samples has enhanced degrees of freedom as compared to the inorganic surface of plain Ti. As to biological evaluations, the biochemically modified Ti samples are safe in terms of cytotoxicity and in vivo biocompatibility assessment. SaOS-2 cells growth rate is lower on collagen modified surfaces, and no significant difference is detected in terms of alkaline phosphatase production as compared to control Ti. Importantly, implants in rabbit femur show a significant increase of bone growth and bone-to-implant contact in the case of the collagen modified samples, confirming that biochemical modifications of Ti surface can enhance the rate of bone healing as compared to plain Ti.

—According to the general guidelines presented in the accompanying paper, some relevant examples of common polymer surfaces are analysed and discussed; a number of polymers commercially available or laboratory synthesized have been analysed. In particular, the case of poly(vinyl chloride) (PVC), often considered as peculiar in the literature, is fully analysed on the basis of a new set of well-prepared samples, whose compositions were checked by high-vacuum spectroscopies. 'Equilibrium' contact angles, obtained by a new experimental technique, are presented. The results are, however, preliminary, because the final set of liquids used is not so 'well equilibrated' as possible, from the point of view of acid–base properties. The contact angle data obtained are analysed in a non-linear way to calculate the acid–base components of all the liquids and solids. The results are discussed and compared with those obtained from liquid–liquid interfaces presented in the accompanying paper. The physico-chemical featur...

Adhesion and alignment of primary human gingival fibroblast to Petri dishes were controlled by proper modification of the surface chemistry of the solid substrate. In particular, air plasma (glow-discharge) treatment, coupled to a masking technique, was used to pattern cell-adhesive areas on a cell-adhesion-resistant alginate coated surface. Fibroblasts were successfully confined to the air plasma-treated areas, which show a much greater growth rate and cell density as compared to the original alginate coated surface. Beside the implications for the study of the mechanisms of bio-adhesion at hydrophilic surfaces, these systems can be of interest for a number of applications in dental surgery and materials.

Air plasma treatment, coupled to a masking technique, was used to promote micropatterned cell adhesion onto a cell-adhesion-resistant alginate coated surface. L-929 mouse fibroblasts were successfully confined into 50 μm diameter cell-adhesive areas patterned inside a cell-resistant layer. The plasma treatment performed, albeit very mild, destroys the molecular architecture of the hydrophilic polysaccharide coating, leading to an enhancement of protein adsorption and hence of cell-adhesion. Both the cell-adhesion-resistant and the cell-adhesive regions are hydrophilic, yet they show a completely different behavior towards cells. Thus, they are a very interesting subject in the study of interfacial interactions in aqueous media, and, in particular, on the mechanisms of bio-adhesion at hydrophilic surfaces.

The atomic force microscope (AFM) was used to acquire force versus distance curves between the cantilever tip and samples bearing a surface overlayer of covalently linked alginic acid. The alginic acid coating resists cell-adhesion in in vitro experiments involving a normal and a tumor cell line. However, the surface becomes cell adhesive when alginic acid coated samples are subjected to glow discharge treatment. Force curves show in both cases the typical features resulting from the interaction between the cantilever tip and a hydrophilic, compressible polymer overlayer, suggesting that in both cases a diffuse interface with water exists. Following some recent findings on oligoethyleneglycol-terminated self-assembled-monolayers, it is suggested that conformational and molecular aspects of hydrophilic surface layers, rather than steric repulsion effects, could play a significant role in the mechanism that controls resistance to bio-adhesion.

A model system involving a polyanionic alginic acid (AA) overlayer ionically immobilized on a polycationic polyethyleneimine underlayer, in turn linked to plasma oxidized polystyrene, was used to investigate the relationship between surface structure properties and resistance to cell adhesion. X-ray Photoelectron Spectroscopy (XPS) and water contact angle measurement were used to characterize the surfaces and to compare the results with data on resistance to adhesion of L-929 fibroblasts. A overlayer model was used to account for the XPS results in terms of fractional coverage by AA. Results show the strong effect of the surface density of AA chains on resistance to cell adhesion and underline the inadequacy of simple relationships between wettability by water and cell adhesion.

A simple model was developed for the interpretation of results stemming from the XPS analysis of polymer surfaces modified by polyethyleneimine adsorption followed by surface coupling of polysaccharides. Theoretical surface compositions were evaluated from the calculated XPS intensity arising from a layered structure composed of a surface oxidized polymer, an intermediate polyethyleneimine layer and a top polysaccharide layer. Results of calculations were compared to analytical data obtained from fixed-angle XPS analysis of polysaccharide-coated surfaces and to the performances of the latter in in vitro cell adhesion experiments. It is shown that the model can correctly predict the relationship between the experimental surface composition and the cell-resistant properties of polysaccharide-coated surfaces. © 1998 John Wiley & Sons, Ltd.

Polystyrene surfaces have been modified by poly(N-isopropylacrylamide) (PIPAAm) grafting. Beside observing the adhesion and the effect of low-temperature treatment on anchorage-dependent cells, the wetting behavior of PIPAAm-grafted surfaces was studied by dynamic contact angle measurement by Wilhelmy microbalances. Measurements were performed in water at different temperatures and at different speeds of immersion. Contact angle behavior has been explained in terms of heterogeneity of the surfaces, using a slightly modified hysteresis graph. The apparent inversion of advancing and receding contact angles shown at high speeds of immersion has been analyzed in terms of kinetic effect, and it is underlined the lack of a similar critical approach in existing literature data.

—This paper presents a review of the theories based on wetting measurements/interfacial thermodynamics most frequently used to explain bacterial adhesion to solid surfaces. The physical meaning of data stemming from the application of the different theories is discussed and compared with current knowledge on interactions between components of matter. It is underlined that existing theories are either in disagreement with accepted knowledge on interfacial interactions or yield conflicting results from a quantitative point of view. It is concluded that, according to the present state of the art, no completely satisfactory theory exists, and that theoretical and experimental difficulties still hinder the understanding of the relationship between surface/interface free energy and bacterial adhesion to solid substrates. The recognition of existing shortcomings should be the first step towards a more satisfactory state of the art.

Low-voltage scanning electron microscopy (LV-SEM) was used to monitor contamination by carbonaceous compounds on the surface of two different commercially available titanium dental implants. Because of its higher surface sensitivity, the LV mode allows us to image contaminating materials on surfaces that are undetected by conventional SEM. Results stemming from LV-SEM observations were compared to surface composition data obtained by XPS analysis. A good relationship between findings obtained by the two techniques was found. © 1997 John Wiley & Sons, Ltd.

Purpose This study was conducted to analyze how a cleaning treatment using plasma of argon would affect fibroblast growth on titanium disks at different time points to determine whether this treatment could enhance soft tissue healing around titanium dental implant abutments. Materials and methods Sixty sterile disks made of machined grade 5 titanium were divided into two groups; 30 disks were left untreated (control) and 30 were cleaned using plasma of argon (test). To simulate clinical conditions during soft tissue healing around titanium abutments, both groups were immersed in a culture of murine fibroblasts (L929) for 2, 8, or 48 hours. After preparation, they were stained using 4',6-diamidino-2-phenylindole dihydrochloride (DAPI) to label the cellular nuclei and fluorescent phalloidin to label the cellular bodies. The nuclei were counted, and cellular bodies were analyzed with fluorescent microscopy and imaging analysis software. Analysis was performed at the three different time points. Results Fibroblast adhesion for the test group was statistically significantly greater versus the control group at 2 and 8 hours but not at 48 hours. At 2 and 8 hours, the cellular bodies in the test group appeared flatter and more spread out, revealing more advanced cellular adhesion, compared to the cells observed in the control group. At 48 hours, the test and control specimens were nearly indistinguishable. Conclusion The removal of organic and inorganic contaminants from the surfaces of titanium disks using plasma of argon accelerated fibroblast adhesion in the early stages of colonization (2 to 8 hours). This effect disappeared after 48 hours as a result of saturation. Clinically, abutment cleaning using plasma of argon might positively affect soft tissue healing in early stages.

Bone reconstruction after tissue loosening due to traumatic, pathological or surgical causes is in increasing demand. 3D scaffolds are a widely studied solution for supporting new bone growth. Bioactive glass–ceramic porous materials can offer a three-dimensional structure that is able to chemically bond to bone. The ability to surface modify these devices by grafting biologically active molecules represents a challenge, with the aim of stimulating physiological bone regeneration with both inorganic and organic signals. In this research work glass ceramic scaffolds with very high mechanical properties and moderate bioactivity have been functionalized with the enzyme alkaline phosphatase (ALP). The material surface was activated in order to expose hydroxyl groups. The activated surface was further grafted with ALP both via silanization and also via direct grafting to the surface active hydroxyl groups. Enzymatic activity of grafted samples were measured by means of UV–vis spectroscopy before and after ultrasonic washing in TRIS–HCl buffer solution. In vitro inorganic bioactivity was investigated by soaking the scaffolds after the different steps of functionalization in a simulated body fluid (SBF). SEM observations allowed the monitoring of the scaffold morphology and surface chemical composition after soaking in SBF. The presence of ALP enhanced the in vitro inorganic bioactivity of the tested material.

Grafting of the biomaterial surfaces with biomolecules is nowadays a challenging research field for prosthetic and bone tissue engineering applications. On the other hand, very few research works investigate the effect of the sterilization processes on the properties of functionalized biomaterials. In this study, the effects of different sterilization techniques (e.g. gamma and electron beam irradiation, ethylene oxide) on the enzymatic activity of bioactive glasses and Ti6Al4V grafted with alkaline phosphatase (ALP) have been analyzed. Sterility maintenance and in vitro bioactivity of the sterilized surfaces have also been investigated. Finally the effect of packaging and storage conditions has been considered.

The goal of the study was the evaluation of the effect of biochemical surface modification by collagen on the bone response to acid-etched titanium surfaces. Fibrillar type I porcine collagen was adsorbed and covalently linked to acid-etched Ti disks and implants. Adhesion, growth, and specific alkaline phosphatase (ALP) activity of osteoblast-like SaOS2 cells were evaluated. Implants in the femur and tibia of rabbit were performed for 2 and 4 weeks and relevant bone to implant contact (BIC) was evaluated by histomorphometry. Results show that cell morphology and growth are controlled by the rough acid-etched implants topography. Specific metabolic activity (ALP) is significantly increased by the collagen overlayer. Importantly, surface modification by collagen increases the speed of periimplant bone formation, resulting in significantly higher BIC both in femur and tibia at 2 weeks. These results suggest that morphological (surface topography) and biochemical (surface linking of bioactive molecules) cues can cooperate and yield multifunctional implant surfaces. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.

Bone integration of orthopaedic or dental implants and regeneration of damaged bone at the surgical site are still unresolved problems in prosthetic surgery. For this reason, biomimetic surfaces (i.e. both inorganic and biological bioactive surfaces) represent a challenge for bone implantation. In this research work a hydrolase enzyme (alkaline phosphatase) was covalently grafted to inorganic bioactive glass and glass ceramic surfaces, in order to impart biological bioactivity. The functionalized samples were analysed by means of X-ray photoelectron spectroscopy in order to verify enzyme presence on the surface. Enzyme activity was measured by means of UV–visual spectroscopy after reaction with the natural substrate. Scanning electron microscopy–energy-dispersive spectroscopy observations allowed monitoring of the morphological and chemical modification of the materials during the different steps of functionalization. In vitro inorganic bioactivity was investigated by soaking samples in simulated body fluid. Enzymatic activity of the samples was tested and compared before and after soaking. Enzymatic activity of the solution was monitored at different experimental times. This study demonstrates that alkaline phosphatase could be successfully grafted onto different bioactive surfaces while maintaining its activity. Presence of the enzyme in vitro enhances the inorganic bioactivity of the materials tested.