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Recent advances in optical imaging techniques rely on the use of nanosized contrast agents for in vitro and in vivo applications. We report on an imaging method based on the inertial cavitation of ultrasound-irradiated water solutions that lead to sonoluminescence (SL), here, newly proposed in combination with semiconductor nanoparticles, in particular, aminopropyl-functionalized zinc oxide nanocrystals. The obtained measurements confirm the ability of such nanocrystals to increase the sonoluminescence emission, together with the ability to modify the SL spectrum when compared to the pure water behavior. In particular, it is shown that the UV component of SL is absorbed by the semiconductor behavior that is also confirmed in different biologically relevant media. Finally, optical images of nanocrystal-assisted SL are acquired for the first time, in particular, in biological buffers, revealing that at low ultrasound intensities, SL is measurable only when the nanocrystals are present in solution. All of these results witness the role of amine-functionalized zinc oxide nanocrystals for sonoluminescence emission, which makes them very good candidates as efficient nanocontrast agents for SL imaging for biological and biomedical applications.

Background The risk of femoral neck fracture progressively increases with age. However, the reasons behind this consistent increase in the fracture risk can't be completely justified by the decrease in the bone mineral density. The objective of this study was to analyze the correlation between various bone structural features and age. Study Design & Methods A total of 29 consecutive patients who suffered an intracapsular hip fracture and underwent joint replacement surgery between May 2012 and March 2013 were included in this study. A 2 cm × 1 cm O cylindrical trabecular bone sample was collected from the femoral heads and preserved in formaldehyde. Bone mineral density (BMD), microarchitecture, organic content and crystallography were analyzed using a Dual-energy X-ray absorptiometry scan, micro-CT scan, and high resolution magic-angle-spinning-nuclear magnetic resonance (MAS-NMR), respectively. Statistical correlations were made using Spearman´s or Pearson´s correlation tests depending on the distribution of the continuous variables. Results The mean patient age was 79.83 ± 9.31 years. A moderate negative correlation was observed between age and the hydrogen content in bone (1H), which is an indirect estimate to quantify the organic matrix (r = −0.512, p = 0.005). No correlations were observed between BMD, trabecular number, trabecular thickness, phosphorous content, apatite crystal size, and age (r = 0.06, p = 0.755; r = −0.008, p = 0.967; r = −0.046, p = 0.812; r = −0.152, p = 0.430, respectively). A weak positive correlation was observed between Charlson´s comorbidity index (CCI) and c-axis of the hydroxiapatite (HA) crystals (r = −0.400, p = 0.035). Conclusion The femoral head relative protein content progressively decreases with age. BMD was not correlated with other structural bone parameters and age. Patients with higher comorbidity scores had larger HA crystals. The present results suggest that the progressive increase in the hip fracture risk in elderly patients could be partially explained by the lower bone protein content in this age group.

Purpose A new type of diazonium-based adhesive has been recently developed by our team to bind dental alloys (Titanium, stainless steel, and cobalt chromium) to dental polymers. Here, we explored the endurance of the resulting adhesive after thermal-cycling and autoclave aging. Materials and methods Polished samples of titanium (Ti), stainless steel (SS) and cobalt chromium (Co-Cr) were coated with a diazonium-based adhesive. Untreated samples served as controls (n = 12 per each condition). X-ray photoelectron spectroscopy (XPS) was performed to characterize the elemental compositions of the different surfaces. Biocompatibility of the coated alloys was assessed with human gingival fibroblasts (HGF). Inductively coupled plasma (ICP) and total organic carbon (TOC) analyses were used to quantify the ions and organic matters released from the diazonium coated alloys. Endurance of the adhesives was assessed by exposing the samples to autoclaving and thermal-cycling. The tensile strength of the poly(methylmethacrylate) (PMMA)-alloy bond was also tested. Results Results of mechanical testing demonstrated a higher endurance of the coated CoCr, Ti, and SS compared to the uncoated alloys. The human fibroblasts cultured on the substrates remained alive and metabolically active, and the coatings did not release significant amounts of toxic chemicals in solutions. Conclusions The results further support the use of diazonium-based adhesives as new coupling agents for dental applications.

Superparamagnetic iron nanoparticles (SPIONs) have become one of the most useful colloidal systems in nanomedicine. We report here the preparation of new hybrid core@shell systems based on SPION nanoparticles coated with a SiO

During the last four decades, the use of nanoparticles has become an important topic in the fields of nanotechnology. Their potential applications in high diversity areas of research make them practically irreplaceable tools in medicine, biomaterials, catalysis, etc. There are countless methods to afford nanoparticles; however, the reduction of ionic species into atomic material is probably one of the most used pathways to generate nanoparticles in a consistent and controlled manner. In the chemical and biological bottom–up approach, the soluble material is reduced to insoluble atomic clusters which grow until a nanoparticle dispersion occurs. For carrying out these kinds of processes, reagents from multiple sources and different intrinsic properties can be used, thanks to their redox potential. This introductory chapter aims to describe the main redox agents used for the colloidal nanoparticle synthesis, from the most classical to the newest chemistry pathways.

This work reports the study of ZnO-based anodes for the photoelectrochemical regeneration of the oxidized form of nicotinamide adenine dinucleotide (NAD+). The latter is the most important coenzyme for dehydrogenases. However, the high costs of NAD+ limit the use of such enzymes at the industrial level. The influence of the ZnO morphologies (flower-like, porous film, and nanowires), showing different surface area and crystallinity, was studied. The detection of diluted solutions (0.1 mM) of the reduced form of the coenzyme (NADH) was accomplished by the flower-like and the porous films, whereas concentrations greater than 20 mM were needed for the detection of NADH with nanowire-shaped ZnO-based electrodes. The photocatalytic activity of ZnO was reduced at increasing concentrations of NAD+ because part of the ultraviolet irradiation was absorbed by the coenzyme, reducing the photons available for the ZnO material. The higher electrochemical surface area of the flower-like film makes it suitable for the regeneration reaction. The illumination of the electrodes led to a significant increase on the NAD+ regeneration with respect to both the electrochemical oxidation in dark and the only photochemical reaction. The tests with formate dehydrogenase demonstrated that 94% of the regenerated NAD+ was enzymatically active.

11 pags., 7 figs., 1 tab., In this work, we present a luminescence platform that can be used as point of care system for determining the presence and concentration of specific oligonucleotide sequences. This sensor exhibited a limit of detection as low as 50 fM by means of: (i) the use of single-stranded DNA (ssDNA) functionalized magnetic microparticles that captured and concentrated ssDNA-upconverting nanoparticles (ssDNA-UCNPs) on a solid support, when the target sequence (miR-21-5p DNA-analogue) was in the sample, and (ii) a photoligation reaction that covalently linked the ssDNA-UCNPs and the ssDNA magnetic microparticles, allowing stringent washes. The presented sensor showed a similar limit of detection when the assays were conducted in samples containing total miRNA extracted from human serum, demonstrating its suitability for detecting small specific oligonucleotide sequences under real-like conditions. The strategy of combining UCNPs, magnetic microparticles, and a photoligation reaction provides new insight into low-cost, rapid, and ultra-sensitive detection of oligonucleotide sequences., This work was supported by Ministerio de Economía y Competi- tividad (MAT2017-83111R and PID2019-106820RB-C21), Ministerio de Ciencia, Innovacion, y Universidades (MICINN, RTI2018-094859) and Comunidad de Madrid (B2017/BMD-3867 RENIM-CM) co-financed by European Structural and Investment Fund. D.M.G. thanks UCM-Santander for a predoctoral contract (CT17/17- CT18/17) and a Postdoctoral Orientation Period (POP) contract. P. S. I. thanks CONICYT for a predoctoral contract (N° 21161052). F. V. D. thanks to European Commission for a YEI program contract (PEJD-2018-PRE/IND-9118). TEM images were obtained at the National Center for Electron Microscopy (UCM, Madrid) facility

The discovery of novel catalytic materials showing unprecedented properties and improved functionalities represents a major challenge to design advanced oxidation processes for wastewater purification. In this work, antimony (Sb) doping is proposed as a powerful approach for enhancing the photo- and piezocatalytic performances of piezoelectric zinc oxide (ZnO) thin films. To investigate the role played by the dopant, the degradation of Rhodamine-β (Rh-β), a dye pollutant widely present in natural water sources, is studied when the catalyst is irradiated by ultraviolet (UV) light or ultrasound (US) waves. Depending on the doping level, the structural, optical, and ferroelectric properties of the catalyst can be properly set to maximize the dye degradation efficiency. Independently of the irradiation source, the fastest and complete dye degradation is observed in the presence of the doped catalyst and for an optimal amount of the inserted dopant. Among ZnO:Sb samples, the most doped one (5 at. %) shows improved UV light absorption and photocatalytic properties. Conversely, the piezocatalytic efficiency is maximized using the lowest Sb amount (1 at. %). The superior ferroelectric polarization observed in this case highly favors the adsorption of electrically charged species, in particular of the dye in the protonated form (Rh-β+) and of OH-, to the catalyst surface and the production of hydroxyl radicals responsible for dye degradation.

Metallic nanostructures have the potential to modify the anti-Stokes emission of upconverting nanoparticles (UCNPs) by coupling their plasmon resonance with either the excitation or the emission wavelength of the UCNPs. In this regard gold nanoparticles (AuNPs) have often been used in sensors for UCNP luminescence quenching or enhancement, although systematic studies are still needed in order to design optimal UCNP-AuNP based biosensors. Amidst mixed experimental evidence of quenching or enhancement, two key factors arise: the nanoparticle distance and nanoparticle size. In this work, we synthesize AuNPs of different sizes to assess their influence on the luminescence of UCNPs. We find that strong luminescence quenching due to resonance energy transfer is preferentially achieved for small AuNPs, peaking at an optimal size. A further increase in the AuNP size is accompanied by a reduction of luminescence quenching due to an incipient plasmonic enhancement effect. This enhancement counterbalances the luminescence quenching effect at the biggest tested AuNP size. The experimental findings are theoretically validated by studying the decay rate of the UCNP emitters near a gold nanoparticle using both a classical phenomenological model and the finite-difference time-domain method. Results from this study establish general guidelines to consider when designing sensors based on UCNPs-AuNPs as donor-quencher pairs, and suggest the potential of plasmon-induced luminescence enhancement as a sensing strategy.

In this work, we explore a photochemical ligation reaction to covalently modify oligonucleotide-conjugated upconverting nanoparticles (UCNPs) in the presence of a specific target DNA sequence. The target sequence acts as a hybridization template, bringing together a biotinylated photoactivatable oligonucleotide probe and the oligonucleotide probe that is attached to UCNPs. The illumination of the UCNPs by NIR light to generate UV emission internally or illuminating the photoactivatable probe directly by an external UV light promotes the photochemical ligation reaction, yielding covalently biotin functionalized UCNPs that can be selectively captured in streptavidin-coated microwells. Following this strategy, we developed a DNA sensor with a limit of detection of 1 × 10-18 mol per well (20 fM). In addition, we demonstrate the possibility to create UCNP patterns on the surface of solid supports upon NIR illumination that are selectively formed under the presence of the target oligonucleotide.

Oral hygiene and regular maintenance are crucial for preserving good peri-implant health. However, available prophylaxis products and toothpastes, which are optimized for cleaning teeth, tend to contaminate and abrade implant surfaces due to their organic components and silica microparticles, respectively. This study aims to develop an organic-free implant-paste based on two-dimensional nanocrystalline magnesium phosphate gel and hydrated silica nanoparticles (20-30% w/w) for cleaning oral biofilm on titanium dental implants. The surface chemistry, morphology, and bacterial load of contaminated Ti disks before and after decontamination using prophylaxis brushing with toothpaste and implant-paste were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, and fluorescence spectroscopy. Both commercial toothpastes and implant-paste remove bacteria, however, only implant-paste protects Ti metal from abrasion and removes organic contaminants. XPS showed a significant decrease of carbon contamination from 73% ± 2 to 20% ± 2 after mechanical brushing with implant-paste compared to 41% ± 11 when brushing with commercial toothpastes (p

Forster resonant energy transfer (FRET) with upconverting nanoparticles (UCNPs) as donors and quantum dots (QDs) as acceptors has been regarded as a promising tool for biosensing applications. In this work, we use time-resolved luminescence spectroscopy to analyze the UCNP-to-QD FRET and we focus on the most relevant parameter of the FRET phenomenon, UCNP–QD distance. This distance is controlled by a nanometric silica shell around the UCNP surface. We theoretically reproduce the experimental results applying FRET theory to the distribution of emitting erbium ions in the UCNP. This simple model allows us to estimate the contribution of every erbium ion to the final FRET response and to explore different strategies to improve FRET efficiency.

This paper presents a critical review and the state of the art of graphene porous membranes, a brand-new technology and backdrop to discuss its potential application for efficient water desalination in low salinity water injection (LSWI). LSWI technology consists in injecting designed, adequately modified, filtered water to maximize oil production. To this end, desalination technologies already available can be further optimized, for example, via graphene membranes, to achieve greater efficiency in water-oil displacement. Theoretical and experimental applications of graphene porous membranes in water desalination have shown promising results over the last 5-6 years. Needless to say, improvements are still needed before graphene porous membranes become readily available. However, the present work simply sets out to demonstrate, at least in principle, the practical potential graphene membranes would have in hydrocarbon recovery processes.

Purpose This research aimed to assess whether pink-shaded anodized surfaces could enhance the adhesion of soft tissue cells compared with untreated machined titanium surfaces. Materials and methods Two types of Ti-Al-V titanium samples were prepared: machined titanium (Ti) and anodized titanium (AnoTi). The microstructure was studied by means of a scanning electron microscope. X-ray photoelectron spectroscopy (XPS) was carried out as well. The wetting properties were investigated by the sessile drop technique with water and diiodomethane. To investigate the biologic response in vitro, the epithelial cell line HaCaT and the fibroblastic cell line NHDF were used. Cell adhesion, morphology, and proliferation were evaluated. Results The microstructure of the tested surfaces was irregularly smooth for both types of samples with no relevant morphologic differences. The XPS and HR-XPS performed on the AnoTi samples confirmed the presence of Ti, O, and C, along with Ti oxides. Following the optical contact angle measurements, the anodization process induced a slight transition toward the hydrophobic regime. Consequently, the surface free energy values differed significantly between the anodized and the machined samples. Anodized Ti significantly increased the adhesion and proliferation of both epithelial cells and fibroblasts when compared with the pristine Ti controls. Conclusion Compared with the clinical standard, anodized surfaces could enhance the adhesion of the two major cell types within the peri-implant soft tissues, which makes pink anodization a promising option for implant dentistry.

Silicon-based materials present a high potential for dental implant applications, since silicon has been proven necessary for the correct bone formation in animals and humans. Notably, the addition of silicon is effective to enhance the bioactivity of hydroxyapatite and other biomaterials. The present work aims to expand the knowledge of the role exerted by hydrogen in the biological interaction of silicon-based materials, comparing two hydrogenated amorphous silicon coatings, with different hydrogen content, as means to enhance soft tissue cell adhesion. To accomplish this task, the films were produced by plasma enhanced chemical vapor deposition (PECVD) on titanium substrates and their surface composition and hydrogen content were analyzed by means of X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectrophotometry (FTIR) respectively. The surface energy and roughness were measured through optical contact angle analysis (OCA) and high-resolution mechanical profilometry respectively. Coated surfaces showed a slightly lower roughness, compared to bare titanium samples, regardless of the hydrogen content. The early cell responses of human keratinocytes and fibroblasts were tested on the above mentioned surface modifications, in terms of cell adhesion, viability and morphometrical assessment. Films with lower hydrogen content were endowed with a surface energy comparable to the titanium surfaces. Films with higher hydrogen incorporation displayed a lower surface oxidation and a considerably lower surface energy, compared to the less hydrogenated samples. As regards mean cell area and focal adhesion density, both a-Si coatings influenced fibroblasts, but had no significant effects on keratinocytes. On the contrary, hydrogen-rich films increased manifolds the adhesion and viability of keratinocytes, but not of fibroblasts, suggesting a selective biological effect on these cells.

As a starting cement material, brushite is beneficial due to its short setting time and fast resorbability, and is metastable, allowing in vivo and in vitro transformation into a more stable calcium phosphate (CaP) phase. The challenges for a successful application of brushite include tissue inflammation from its acidic nature, and poor mechanical strength from weakly compacted crystals. Thus, in this study, it is aimed to avoid these drawbacks through a chemical modification of brushite cement. To circumvent tissue inflammation, brushite was modified with 5% of K+ or Mg2+ to induce the transformation into a more stable phase like hydroxyapatite (HAp). Surface transformation in a Tas-stimulated body fluid (Tas-SBF) solution occurred faster for K+-modified cements (1 week, to HAp and β-TCP) than for unmodified brushite (2 weeks, to HAp), and Mg2+-modified brushite (2 weeks, to HAp and β-TCP). Bulk transformation depended on the penetration of the Tas-SBF solution. Thus, Mg2+-substituted cement exhibited the most apatitic structure (26 wt%) due to the highest porosity. To improve the mechanical properties of brushite, setting retardants (acid pyrophosphate, citric acid) and an excess amount of β-TCP as a filler material were included in the cement’s composition. Diametral tensile strength (DTS) was the highest for unsubstituted cements (4.96 ± 1.04 MPa), slightly lower for K+-enriched cement (4.01 ± 0.71 MPa), and lowest for Mg2+-doped cements (1.34 ± 0.23 MPa). This study shows that it is possible to induce the transformation of brushite cement into a more biocompatible bone-like cement and simultaneously achieve enhanced mechanical properties through compositional modification of the cement.

Restoration of soft tissue defects remains a challenge for surgical reconstruction. In this study, we introduce a new approach to fabricate poly(d,l-lactic acid) (PDLLA) scaffolds with anatomical shapes customized to regenerate three-dimensional soft tissue defects. Highly concentrated polymer/salt mixtures were molded in flexible polyether molds. Microcomputed tomography showed that with this approach it was possible to produce scaffolds with clinically acceptable volume ratio maintenance (>90%). Moreover, this technique allowed us to customize the average pore size and pore interconnectivity of the scaffolds by using variations of salt particle size. In addition, this study demonstrated that with the increasing porosity and/or the decreasing of the average pore size of the PDLLA scaffolds, their mechanical properties decrease and they degrade more slowly. Cell culture results showed that PDLLA scaffolds with an average pore size of 100 µm enhance the viability and proliferation rates of human gingival epithelial cells up to 21 days. The simple method proposed in this article can be extended to fabricate porous scaffolds with customizable anatomical shapes and optimal pore structure for epithelial tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 880-890, 2018.

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Upconversion nanoparticles (UCNP) are increasingly used due to their advantages over conventional fluorophores, and their use as resonance energy transfer (RET) donors has permitted their application as biosensors when they are combined with appropriate RET acceptors such as graphene oxide (GO). However, there is a lack of knowledge about the design and influence that GO composition produces over the quenching of these nanoparticles that in turn will define their performance as sensors. In this work, we have analysed the total quenching efficiency, as well as the actual values corresponding to the RET process between UCNPs and GO sheets with three different chemical compositions. Our findings indicate that excitation and emission absorption by GO sheets are the major contributor to the observed luminescence quenching in these systems. This challenges the general assumption that UCNPs luminescence deactivation by GO is caused by RET. Furthermore, RET efficiency has been theoretically calculated by means of a semiclassical model considering the different nonradiative energy transfer rates from each Er3+ ion to the GO thin film. These theoretical results highlight the relevance of the relative positions of the Er3+ ions inside the UCNP with respect to the GO sheet in order to explain the RET-induced efficiency measurements.

The bone regenerative capacity of synthetic calcium phosphates (CaPs) can be enhanced through the enrichment with selected metal trace ions. However, defining the optimal elemental composition required for bone formation is challenging due to many possible concentrations and combinations of these elements. We hypothesized that the ideal elemental composition exists in the inorganic phase of the bone extracellular matrix (ECM). To study our hypothesis, we first obtained natural hydroxyapatite through the calcination of bovine bone, which was then investigated its reactivity with acidic phosphates to produce CaP cements. Bioceramic scaffolds fabricated using these cements were assessed for their composition, properties, and in vivo regenerative performance and compared with controls. We found that natural hydroxyapatite could react with phosphoric acid to produce CaP cements with biomimetic trace metals. These cements present significantly superior in vivo bone regenerative performance compared with cements prepared using synthetic apatite. In summary, this study opens new avenues for further advancements in the field of CaP bone biomaterials by introducing a simple approach to develop biomimetic CaPs. This work also sheds light on the role of the inorganic phase of bone and its composition in defining the regenerative properties of natural bone xenografts.

The fluorescence quenching mechanism of the conjugated polymer poly[5-​methoxy-​2-​(3-​sulfopropoxy)​-​1,4-​phenylenevinylene] by cytochrome c was investigated. Experiments with the ferrous and the ferric protein indicated that saturation of the accessible quenching sites of the fluorophore was reached at lower concentrations for the ferrous protein. The Stern-Volmer constants obtained were in the same order of magnitude (1.71 × 106 and 3.92 × 106 M−1), for ferrous and ferric protein, respectively, which seems to indicate that photoinduced electron transfer between the iron atom of the protein and the conjugated polymer is not the fluorescence quenching mechanism. Dynamic light scattering measurements indicated the formation of a complex, driven by Coulomb attractive interactions, between the positively charged protein and the negatively charged polymer. Furthermore, time-resolved fluorescence spectroscopy experiments together with the overlap of the fluorescent emission band of the polymer and the absorption band of the protein, revealed that the fluorescence quenching mechanism involved is mainly due to the formation of a ground state complex although resonance energy transfer may also occur.

Bacterial contamination on titanium implants can cause inflammation and eventually implant failure. Currently used methods for decontamination of implants have demonstrated limited success. Metal surfaces can be disinfected electrochemically. However, the effect of electrochemical treatments on biofilm-contaminated titanium is largely unknown. We hypothesized that electrochemical treatments are able to safely remove organic contamination and bacteria from titanium implants without altering their surfaces. This study was designed to assess the electrochemical properties of bacteria-contaminated surfaces in order to develop new treatments to clean titanium. Surface morphology, composition, bacterial load, and electrochemical properties of polished titanium discs were analyzed before and after biofilm contamination and subsequent decontamination with various electrochemical methods. The effect of the combination of the electrochemical with titanium brush cleaning was also evaluated. Results were then analyzed and compared to baseline readings (prior to contamination) using repeated measures ANOVA. Biofilm contamination increased the levels of carbon, nitrogen, and live bacteria on titanium surfaces while reducing their open circuit potential and corrosion resistance. Optimized electrochemical treatments with alternating current (-2.3 mA, + 22.5 μA) and voltages (1.8 V), were bactericidal and able to completely decontaminate saliva-contaminated titanium surfaces within 5 min while preserving surface integrity and histological quality of mammalian tissues. Furthermore, with the aid of mechanical brushing, the optimized electrochemical treatment was able to achieve complete decontamination of biofilm-contaminated Ti surfaces. The electrochemical treatment seems to be promising and well worth investigating for the clinical management of peri-implant infections.

Three different single-lumen double-J ureteral stents of different materials were studied and compared after the insertion into a dynamic in vitro model with sterile artificial urine up to 6 months. The aim was to evaluate, at selected time steps of 1, 3, and 6 months, the material performances of the stents in preventing the formation of inorganic encrustations. Morphological, compositional, and qualitative analyses were carried out both before stent insertion and after stent permanence for the different time steps, showing an increasing level of encrustation which remains particularly low in the case of two polyurethane stents. Mechanical tests show that both the polyurethane stents and the chitosan one do not decrease the tensile strength after 6 months of indwelling. Evaluation of the wetting behavior of the stent outer surfaces indicates a hydrophilic behavior in most of the cases, which is generally preserved after immersion in artificial urine for the different time steps. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2244-2253, 2017.

Objectives Current decontamination methods of titanium (Ti) implant present limited success in achieving predictable re-osseointegration. We hypothesized that even though these techniques could be useful in elimination of bacteria, they might be unsuccessful in removing organic contaminants and restoring the original surface composition. The aim of this study was to assess the effect of four decontamination methods on the surface chemistry and bacterial load of biofilm-contaminated implant surfaces in order to improve implant surface decontamination. Material and methods The ability of clinically available methods such as metal and plastic curettes, Ti brushes and Er: YAG laser to decontaminate Ti implant surfaces was assessed. Surface morphology, chemical composition and properties of machined Ti discs (O 5.0 and 1.0 mm thick) were analysed before and after oral biofilm contamination using scanning electron microscope and X-ray photoelectron spectroscopy. The presence and viability of bacteria were evaluated with live–dead assays. Results Biofilm contamination created an organic layer rich in hydrocarbons and bacteria that covered entirely the Ti surfaces. This organic layer has tightly adhered to Ti surfaces and could not be completely removed with any of the methods assessed. Ti brushes achieved greater elimination of organic contaminants and bacteria than curettes and Er: YAG laser; however, none of them was able to restore the original surface chemistry. Alternatively, Er: YAG laser-treated surfaces showed the lowest live-to-dead bacterial ratio. Conclusions Ti brushes were more effective than curettes (metal or plastic) and Er: YAG laser in decontaminating Ti implant surfaces, although none of these techniques was able to completely eliminate surface contamination. Er: YAG laser was more effective than curettes and Ti brushes in killing the biofilm bacteria.

We developed a sensor for the detection of specific microRNA (miRNA) sequences that was based on graphene quantum dots (GQDs) and ssDNA-UCNP@SiO2. The proposed sensor exploits the interaction between the sp(2) carbon atoms of the GQD, mainly π-π stacking, and the DNA nucleobases anchored on the upconversion nanoparticles (UCNPs). This interaction brings the GQD to the surface of the ssDNA-UCNP@SiO2 system, enhancing the upconversion emission. On the other hand, hybridization of the single-stranded DNA (ssDNA) chains anchored on the nanoparticles with their complementary miRNA sequences blocks the capacity of the UCNPs to interact with the GQD through π-π stacking. That gives as result a reduction of the fluorescent enhancement, which is dependent on the concentration of miRNA sequences. This effect was used to create a sensor for miRNA sequences with a detection limit of 10 fM.

Plastic smart windows are becoming one of the key elements in view of the fabrication of inexpensive, lightweight electrochromic (EC) devices to be integrated in the new generation of high-energy-efficiency buildings and automotive applications. However, fabricating electrochromic devices on polymer substrates requires a reduction of process temperature, so in this work we focus on the development of a completely room-temperature deposition process aimed at the preparation of ITO-coated polycarbonate (PC) structures acting as transparent and conductive plastic supports. Without providing any substrate heating or surface activation pretreatments of the polymer, different deposition conditions are used for growing indium tin oxide (ITO) thin films by the radiofrequency magnetron sputtering technique. According to the characterization results, the set of optimal deposition parameters is selected to deposit ITO electrodes having high optical transmittance in the visible range (∼90%) together with low sheet resistance (∼8 ohm/sq). The as-prepared ITO/PC structures are then successfully tested as conductive supports for the fabrication of plastic smart windows. To this purpose, tungsten trioxide thin films are deposited by the reactive sputtering technique on the ITO/PC structures, and the resulting single electrode EC devices are characterized by chronoamperometric experiments and cyclic voltammetry. The fast switching response between colored and bleached states, together with the stability and reversibility of their electrochromic behavior after several cycling tests, are considered to be representative of the high quality of the EC film but especially of the ITO electrode. Indeed, even if no adhesion promoters, additional surface activation pretreatments, or substrate heating were used to promote the mechanical adhesion among the electrode and the PC surface, the observed EC response confirmed that the developed materials can be successfully employed for the fabrication of lightweight and inexpensive plastic EC devices.

The use of nanomaterials in the field of bone tissue engineering implants is continuously dealing with the development of innovative solutions to common problems, as infection by colonization with common microbial agents, antibiotic bacterial resistance, and the formation of new bone tissue. Among them, ZnO nanostructures are promising candidates thanks to their intrinsic antimicrobial activity and high biocompatibility. In this paper we aim to analyse the behaviour of ZnO nanocrystals (ZnO NCs), prepared with a new synthetic approach and not embedded in any composite matrix, for bone implants applications in-vitro. In particular, we have developed a novel, fast and reproducible microwave-assisted synthesis, obtaining highly-crystalline, round-shaped ZnO NCs of 20 nm in diameter as an extremely-stable colloidal solution in ethanol. Part of them were also chemically functionalized by anchoring amino-propyl groups to the ZnO surface (ZnO-NH2 NCs). Thus, the role of both ZnO NCs concentration and surface chemistry are tested in terms of biocompatibility towards pre-osteoblasts cells, promotion of cell proliferation and differentiation, and also in terms of antimicrobial activity against Gram positive and negative bacteria, such as Escherichia coli and Staphylococcus aureus, respectively. The results propose the ZnO-NH2 NCs as the most promising candidate to solve infections disease in bone implants and promote bone tissue proliferation at the same time, even at high concentrations. Whereas further investigations are needed for example to clarify the mechanism inhibiting biofilm formation and to investigate their role in in-vivo assays, we demonstrated that a fine and reproducible control over the chemical and structural parameters in ZnO nanomaterials can open new horizons in the use of functionalized ZnO NCs as a highly biocompatible and osteoinductive nanoantibiotic agent for bone tissue engineering.

This paper aimed to assess how four different and representative dental implant surfaces (machined MAC, grit blasted GB, acid etched AE and grit blasted acid etched GBAE) could affect cell adhesion possibly modulating protein adsorption and a paramount cell receptor such as α5s1 integrin. Based on non-contact 3D profilometry, GBAE was rougher than the other surfaces, while GB and AE reached similar intermediate Sa values and MAC resulted the smoothest one. According to X-ray Photoelectron Spectroscopy and Raman spectroscopy, all the surfaces showed amorphous titania with similar amounts of carbon contaminants. The lesser protein adsorption and delayed cell adhesion of GB, which did not hinder cell proliferation, were correlated to the altered dispersive to polar SE ratio, that was at least double-fold for GB (2.6) compared to MAC (0.8), SL (1.3) and AE (1.2). The biological response in vitro relied on β1 integrin activation that cooperated with the putative mechano-protein transient receptor potential vanilloid 4 (TRPV4) in determining the adhesion of the osteoblasts. In fact, it could be rescued by over activating β1 integrin. On the other hand, silencing TRPV4 strongly inhibited cell adhesion on selected substrates, proving the role of this protein in mediating osteoblasts adhesion on titanium substrates.

Mesoporous zinc oxide (ZnO) scaffolds coated with drop-cast graphene oxide (GO) flakes are proposed to be a novel bilayer system featuring bioactivity, biocompatibility, and promising loading/release properties for controlled drug-delivery systems. The high-surface-area ZnO scaffolds show clear apatite deposition, but their particular surface chemistry and topography prevent the formation of a continuous coating, resulting in micrometric crystalline apatite aggregates after 28 days in simulated body fluid (SBF). When gentamicin sulfate (GS) is considered as a model molecule, pure ZnO scaffolds also show functional GS loading efficiency, with fast in vitro release kinetics driven by a simple diffusion mechanism. Strikingly, the bioactivity and GS delivery properties of mesoporous ZnO are efficiently triggered by drop-casting GO flakes atop the mesoporous scaffold surface. The resulting ZnO@GO bilayer scaffolds show the formation of a uniform apatite coating after 28 days in SBF and demonstrate a biocompatible behavior, supporting the culture of SaOS-2 osteoblast-like cells. Moreover, the GO coating also leads to a barrier-layer effect, preventing fast GS release, particularly in the short time range. This barrier effect, coupled with the existence of nanopores within the GO structure, sieves drug molecules from the mesoporous ZnO matrix and allows for a delayed release of the GS molecule. We, thus, demonstrated a new-generation ZnO@GO bilayer system as effective multifunctional and biocompatible scaffold for bone tissue engineering.

Background Proton pump inhibitors, over-the-counter drugs taken by millions of patients, diminish bone accrual. Accordingly, we hypothesized that these drugs could impair bone healing and implant osseointegration. This study investigated the effect of post-operative systemic administration of omeprazole on bone healing and implant osseointegration in rat tibiae. Methods In 24 Sprague–Dawley rats, a titanium implant was placed in the left tibia, and a bone defect was created in the right tibia. During the 2 weeks following surgery, 12 rats were treated with omeprazole (5 mg/kg, daily) and the other 12 with saline. Then, after euthanasia, the volume (mm3) of the cortical defect and the percentages of newly formed bone in the defect, were assessed using microcomputed tomography; peri-implant bone volume/tissue volume and bone-implant contact percentage were assessed by histomorphometry. Results Omeprazole-treated rats presented larger cortical defects (2.75 ± 0.59 mm3, p = 0.003 versus 2.11 ± 0.36 mm3; p = 0.002) and a lower percentage of newly formed bone in the defects (28.62 ± 13.12; 45.89 ± 9.73; p = 0.003) than controls. Omeprazole-treated rats presented lower peri-implant bone volume/tissue volume (14.3 ± 7.3% versus 30.8 ± 11.0%; p

ZnO nanomaterials are gaining lots of attention due to their biocompatible nature coupled with promising piezoelectric properties, envisioning a new generation of lead-free smart materials. Herein, an effective strategy to improve the piezoelectric behaviour of sputtered ZnO thin films is proposed by introducing a nanobranched porous thin film structure composed by a network of randomly-oriented wurtzite crystallites, rather than using compact ZnO thin films, considered in this work as a conventional reference for sputtered ZnO thin film structures. The nanobranched ZnO structure shows a hydrophilic behavior together with a piezoelectric output voltage of around 3 V. In comparison, compact ZnO thin films exhibit a maximum piezoelectric voltage generation below 0.8 V and a hydrophobic state. The more defective structure of the nanobranched ZnO thin films, with respect of the long-range ordered crystal structure of compact ZnO thin films, reduces free carrier concentration and mobility, thus limiting the screening potential and at the same time improving piezoelectric voltage generation. All the characterization results highlight the promising perspectives in using nanobranched ZnO thin films as novel piezoelectric materials for biosensing and tissue engineering applications, as well as for lead-free piezoelectric sensors and energy harvesting systems.

This work proposes a novel method to obtain catalytically active gold clusters by using the water-soluble 5,10,15,20-Tetrakis(4-trimethyl-ammonio-phenyl)porphyrin under mild conditions instead of using strong reducing agents. Uniform gold clusters were obtained with a diameter comprised between 1 and 2 nm and long-term stability. Furthermore, the water-soluble porphyrin was immobilized on the SiO2 shell of a core@shell Fe3O4@SiO2 nanoparticles to directly synthesize gold clusters onto the surface of Fe3O4@SiO2 nanoparticles featuring their magnetic recovery. Fe3O4@SiO2@Au nanoparticles were found to be catalytically active for the reduction of 4-nitrophenol to 4-aminophenol using NaBH4 and giving very high pseudo-first-order rate constant comprised between 0.7 and 2.7 min−1. Our results demonstrate that Fe3O4@SiO2@Au nanoparticles are stable catalysts and do not degrade during the catalytic process under the reaction conditions enabling their magnetic recuperation.

ZnO nanostructures are grown by a simple chemical vapour deposition method directly on a stainless steel disc current collector and successfully tested in lithium cells. The structural/morphological characterization points out the presence of well-defined polycrystalline nanostructures having different shapes and a preferential orientation along the c -axis direction. In addition, the high active surface of the ZnO nanostructures, which accounts for a large electrode/electrolyte contact area, and the complete wetting with the electrolyte solution are considered to be responsible for the good electrical transport properties and the adequate electrochemical behaviour, as confirmed by cyclic voltammetry and galvanostatic charge/discharge cycling. Indeed, despite no binder or conducting additives are used, when galvanostatically tested in lithium cells, after an initial decay, the ZnO nanostructures can provide a rather stable specific capacity approaching 70 μA h cm −2 (i.e., around 400 mA h g −1 ) after prolonged cycling at 1 C, with very high Coulombic efficiency and an overall capacity retention exceeding 62%.

Oral hygiene and regular maintenance are crucial for preserving good peri-implant health. However, available prophylaxis products and toothpastes, which are optimized for cleaning teeth, tend to contaminate and abrade implant surfaces due to their organic components and silica microparticles, respectively. This study aims to develop an organic-free implant-paste based on two-dimensional nanocrystalline magnesium phosphate gel and hydrated silica nanoparticles (20-30% w/w) for cleaning oral biofilm on titanium dental implants. The surface chemistry, morphology, and bacterial load of contaminated Ti disks before and after decontamination using prophylaxis brushing with toothpaste and implant-paste were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, and fluorescence spectroscopy. Both commercial toothpastes and implant-paste remove bacteria, however, only implant-paste protects Ti metal from abrasion and removes organic contaminants. XPS showed a significant decrease of carbon contamination from 73% ± 2 to 20% ± 2 after mechanical brushing with implant-paste compared to 41% ± 11 when brushing with commercial toothpastes (p 0.05). Fluorescence microscopy revealed that bacteria load on biofilm contaminated Ti (44 × 10

11 p.-2 schem.-1 graph. abst., We synthesize and characterize pH-responsive hybrid nanocomposites with SERS and drug loading applications. This colloidal system is structured by spherical 50 nm Au cores individually coated by a pH-sensitive shell of poly4-vinylpyridine (Au@p4VP). The synthesis of these hybrid nanocomposites is performed in two steps, a first one involves the fabrication of vinyl-functionalized Au nanoparticles, and a second one includes the controlled overgrowth of a p4VP shell by free radical polymerization. As a result, Au@p4VP hybrid systems with a mean diameter ranging from 150 to 57 nm are obtained upon varying the monomer concentration at synthesis. Au@p4VP nanocomposite exhibits pH-response capabilities, confirmed by cryo-TEM analysis, Small Angle X-ray Scattering (SAXS) and Zeta Potential (ZP) measurements at different pH conditions. The Au@p4VP particles also display a controllable swelling response, which depends on the cross-linker density within the polymer. This swelling capability is analyzed by Dynamic Light Scattering (DLS), and UV–vis spectroscopy at different pHs. The pH-responsive capability is here exploited for the chemical entrapment of doxorubicin hydrochloride (Dox) into the polymer network. The presence of this molecule is resolved by Surface Enhanced Raman Spectroscopy (SERS) measurements. The entrapment efficiency of Dox by the Au@p4VP system is determined via NMR spectroscopy of the supernatants., JCR acknowledges funding from UOC, internal grant N116139473, aimed at enhancing submission to H2020 calls. RCC, JLR and JRR acknowledge financial support from the Spanish MINECO projects CTQ2013-48418P, CTQ2016-76311-R, BFU2016-75319-R and MAT2014-55065R. IF, RCC and ABRM thank the financial support given by Junta de Andalucía (Spain) under the project number P12-FQM-2668. J.F.D acknowledges the networking contributions by the COST actions CM1407 and CM1470.

We present a sensor that exploits the phenomenon of upconversion luminescence to detect the presence of specific sequences of small oligonucleotides such as miRNAs among others. The sensor is based on NaYF4:Yb,Er@SiO2 nanoparticles functionalized with ssDNA that contain azide groups on the 3′ ends. In the presence of a target sequence, interstrand ligation is possible via the click-reaction between one azide of the upconversion probe and a DBCO-ssDNA-biotin probe present in the solution. As a result of this specific and selective process, biotin is covalently attached to the surface of the upconversion nanoparticles. The presence of biotin on the surface of the nanoparticles allows their selective capture on a streptavidin-coated support, giving a luminescent signal proportional to the amount of target strands present in the test samples. With the aim of studying the analytical properties of the sensor, total RNA samples were extracted from healthy mosquitoes and were spiked-in with a specific target sequence at different concentrations. The result of these experiments revealed that the sensor was able to detect 10–17 moles per well (100 fM) of the target sequence in mixtures containing 100 ng of total RNA per well. A similar limit of detection was found for spiked human serum samples, demonstrating the suitability of the sensor for detecting specific sequences of small oligonucleotides under real conditions. In contrast, in the presence of noncomplementary sequences or sequences having mismatches, the luminescent signal was negligible or conspicuously reduced.

In this work, we present a novel method to produce thermoresponsive, monodisperse microgels which display temperature-dependent photoluminescence. The system is based on bimetallic cores of Au@Ag encapsulated within thermoresponsive poly(N-isopropylacrylamide) microgels and coated with a photoluminescent polymer (poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (PTEBS) using the Layer-by-Layer technique. The electromagnetic radiation used to excite the PTEBS induces a local electromagnetic field on the surface of the bimetallic cores that enhances the excitation and emission rates of the PTEBS, yielding a metal enhanced fluorescence (MEF). This effect was studied as a function of the bimetallic core size and the separation distance between the PTEBS and the bimetallic cores. Our results permit evaluation of the effect that the metallic core size of colloidal particles exerts on the MEF for the first time, and prove the relevance of the metallic cores to extend the effect far away from the metallic surface.

A multivariate chemometric approach is proposed for the first time for performance optimization of I−/I3− liquid electrolytes for dye-sensitized solar cells (DSSCs). Over the years the system composed by iodide/triiodide redox shuttle dissolved in organic solvent has been enriched with the addition of different specific cations and chemical compounds to improve the photoelectrochemical behavior of the cell. However, usually such additives act favorably with respect to some of the cell parameters and negatively to others. Moreover, the combined action of different compounds often yields contradictory results, and from the literature it is not possible to identify an optimal recipe. We report here a systematic work, based on a multivariate experimental design, to statistically and quantitatively evaluate the effect of different additives on the photovoltaic performances of the device. The effect of cation size in iodine salts, the iodine/iodide ratio in the electrolyte and the effect of type and concentration of additives are mutually evaluated by means of a Design of Experiment (DoE) approach. Through this statistical method, the optimization of the overall parameters is demonstrated with a limited number of experimental trials. A 25% improvement on the photovoltaic conversion efficiency compared with that obtained with a commercial electrolyte is demonstrated.

Multifunctional, biocompatible, and brush-grafted poly(ethylene glycol)/poly(e-caprolactone) (PEG/PCL) nanoparticles have been synthesized, characterized, and used as vehicles for transporting hydrophobic substances in water. For anchoring the polymer mixed brushes, we used magnetic-silica particles of 40 nm diameter produced by the reverse microemulsion method. The surface of the silica particle was functionalized with biocompatible polymer brushes, which were synthesized by the combination of “grafting to” and “grafting from” techniques. PEG was immobilized on the particles surface, by “grafting to,” whereas PCL was growth by ROP using the “grafting from” approach. By varying the synthetic conditions, it was possible to control the amount of PCL anchored on the surface of the nanoparticles and consequently the PEG/PCL ratio, which is a vital parameter connected with the arrangement of the polymer brushes as well as the hydrophobic/hydrophilic balance of the particles. Thus, adjusting the PEG/PCL ratio, it was possible to obtain a system formed by PEG and PCL chains grafted on the particle's surface that collapsed in segregated domains depending on the solvent used. For instance, the nanoparticles are colloidally stable in water due to the PEG domains and at the same time are able to transport, entrapped within the PCL portion, highly water-insoluble drugs. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2966–2975