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Background: Due to their extremely small size, large surface area, and magnetism, magnetite nanoparticles (Fe3O4NPs) have distinct chemical and physical properties, enhancing their suitability for a variety of medical, biosensing, electronic, and environmental applications. Methods: Magnetite nanoparticles were easily obtained by green synthesis using leaf extracts of the South American endemic Cryptocaria alba (Peumo) tree. FeNPs were characterized by using UV-visible spectrophotometry, Transmission Electronic Microscopy (TEM), Dynamic Light Scattering (DLS), Laser Doppler Velocimetry (LDV), X-ray Diffraction (XRD), and Thermogravimetric Analysis (TGA). Results: Fe3O4NPs were successfully synthetized, and they showed crystalline nature, primary dry diameter means between 12 nm and 15 nm, spherical apparent shape, and good stability in aqueous suspension. Additionally, preliminary studies indicated that low concentrations of magnetite nanoparticles (1000 times lower than the literature reported) reduced chemical oxygen demand (COD), apart from concentrations of total phosphates and nitrates from pisciculture wastewater samples incubated for 24 h. Conclusions: Green synthesis of Peumo iron nanoparticles is an easy, fast, and viable ecofriendly bioprocess under certain conditions of fabrication to obtain nanometric and stable iron particles with promising removal properties of nitrates, phosphates, and COD from wastewaters.

The design and engineering of antibacterial materials are key for preventing bacterial adherence and proliferation in biomedical and household instruments. Silver nanoparticles (AgNPs) and chitosan (CHI) are broad-spectrum antibacterial materials with different properties whose combined application is currently under optimization. This study proposes the formation of antibacterial films with AgNPs embedded in carboxymethylcellulose/chitosan multilayers by the layer-by-layer (LbL) method. The films were deposited onto nanoporous silicon (nPSi), an ideal platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. We focused on two alternative multilayer deposition processes: cyclic dip coating (CDC) and cyclic spin coating (CSC). The physicochemical properties of the films were the subject of microscopic, microstructural, and surface–interface analyses. The antibacterial activity of each film was investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria strains as model microorganisms. According to the findings, the CDC technique produced multilayer films with higher antibacterial activity for both bacteria compared to the CSC method. Bacteria adhesion inhibition was observed from only three cycles. The developed AgNPs–multilayer composite film offers advantageous antibacterial properties for biomedical applications.

According to selective, retentive, scientific realism, past empirical success may be explained only by the parts of past theories that are responsible of their successful predictions being approximately true, and thus theoretically retained, or approximated, by the parts of posterior theories responsible of the same successful predictions. In this article, we present as case study the transit from Ptolemy’s to Kepler’s astronomy, and their successful predictions for Mars’ orbit. We present an account of Ptolemy’s successful prediction of Mars’ orbit from Kepler’s perspective, and scrutinize whether the theoretical elements responsible for Ptolemy’s empirical success are approximately retained in Kepler. In order to give to the realist the best chances, we try different strategies. We conclude that all fail and thereby this case constitutes a prima facie strong anomaly for selective retentive realism. Structural realists may call preservation of structure to the rescue, but the existing notions of structure do not work. In absence of a new notion that works, the burden of the proof lies on the realist side.

The design and engineering of antibacterial materials are key for preventing bacterial adherence and proliferation in biomedical and household instruments. Silver nanoparticles (AgNPs) and chitosan (CHI) are broad-spectrum antibacterial materials with different properties whose combined application is currently under optimization. This study proposes the formation of antibacterial films with AgNPs embedded in carboxymethylcellulose/chitosan multilayers by the layer-by-layer (LbL) method. The films were deposited onto nanoporous silicon (nPSi), an ideal platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. We focused on two alternative multilayer deposition processes: cyclic dip coating (CDC) and cyclic spin coating (CSC). The physicochemical properties of the films were the subject of microscopic, microstructural, and surface–interface analyses. The antibacterial activity of each film was investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria strains as model microorganisms. According to the findings, the CDC technique produced multilayer films with higher antibacterial activity for both bacteria compared to the CSC method. Bacteria adhesion inhibition was observed from only three cycles. The developed AgNPs–multilayer composite film offers advantageous antibacterial properties for biomedical applications.

The layer-structured monoclinic Li2MnO3 is a key material, mainly due to its role in Li-ion batteries and as a precursor for adsorbent used in lithium recovery from aqueous solutions. In the present work, we used first-principles calculations based on density functional theory (DFT) to study the crystal structure, optical phonon frequencies, infra-red (IR), and Raman active modes and compared the results with experimental data. First, Li2MnO3 powder was synthesized by the hydrothermal method and successively characterized by XRD, TEM, FTIR, and Raman spectroscopy. Secondly, by using Local Density Approximation (LDA), we carried out a DFT study of the crystal structure and electronic properties of Li2MnO3. Finally, we calculated the vibrational properties using Density Functional Perturbation Theory (DFPT). Our results show that simulated IR and Raman spectra agree well with the observed phonon structure. Additionally, the IR and Raman theoretical spectra show similar features compared to the experimental ones. This research is useful in investigations involving the physicochemical characterization of Li2MnO3 material.

The layer-structured monoclinic Li

This work was aimed at characterizing the effects of foliarly applied rutile (TiO2) nanoparticles (NPs) on Ti translocation as well as biomass production and antioxidant system in tomato (Solanum lycopersicum L.). The seeds were germinated and grown on a substrate in individual pots in a growth chamber. The TiO2 NPs were characterized using transmission electron microscopy (TEM), Raman spectroscopy, dynamic light scattering (DLS), and laser doppler velocimetry (LDV). Titanium dioxide NPs had a rod-shaped form and were moderately prone to agglomeration. The TiO2 NPs treatments were applied at 0, 5, 10, 20, 40, 80, and 160 mg L−1 by foliar spraying on 20-day-old S. lycopersicum plants. After 7 days of treatment exposure, tissue Ti concentration was determined by inductively coupled plasma-mass spectrometry (ICP-MS). Nanoparticle treatments increased tissue Ti concentration; Ti was translocated from leaves to stem, triggering a significant decrease in biomass production. With respect to the control, an increase in total reducing capacity (1.7-fold), antioxidant activity (1.5-fold), and superoxide dismutase activity (2-fold) were observed in the treatments with intermediate to high doses. The TiO2 NPs triggered an increase in tissue Ti concentration, increasing the antioxidant system activity and lipid peroxidation at low to intermediate doses, and decreasing biomass production at intermediate to high doses.

Nowadays, multiple passenger ridesharing and its variants look one of the more promising emerging mobility concepts. However, the real implementation of these systems accounting specifically requirements for users should raise certain challenges, even further for disabled people, which inherits requirements that need special consideration: short ride times, specific vehicle characteristics depending on the mobility handicaps, narrow time windows constraints, etc. This paper presents the real case study of the public transport service that Barcelona city offers to people with reduced mobility, which could program weekly taxi trips within the city at a specific time. The proposed routing algorithm integrated into this service management system is based on a tabu search heuristic approach used to minimize the dimension of the heterogeneous fleet and the total traveled time. Furthermore, this work exhaustively analyses the operational factors of this mobility service to analyze how they affect the service performance and car-sharing factors. The obtained results show that certain operational decisions could make better use of the resources allocated to the sharing services. This research was funded by Secretaria d’Universitats i Recerca de la Generalitat de Catalunya (2017-SGR-1749).

In the present work, silver nanoparticles (AgNPs) synthetized with Cryptocarya alba (Peumo) leaf extract were studied. The fabrication method was fast, low cost, and eco-friendly, and the final properties of AgNPs were determined by experimental parameters, such as AgNO3 and Peumo extract concentrations used. Setting suitable experimental conditions, crystalline AgNPs with apparent spherical forms and average diameter around 3.5 nm were obtained. In addition, the capability of synthesized Peumo-AgNPs to remove methylene blue dye (MB) in aqueous solution as well as their catalytic effectiveness was also investigated. The results showed that green synthesized AgNPs can remove fast and effectively the MB dye from aqueous medium by itself, but better results were found acting like catalyst by using sodium borohydride (NaBH4) in the reaction. In addition, this green nanomaterial can be recycling several times maintaining initial properties for removal of MB. Thus, AgNPs synthetized with Peumo leaf extracts could be an excellent catalyst candidate for degradation of blue methylene dye in chemical industries.

“This is the Accepted Manuscript version of an article accepted for publication in Nanotechnology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6528/ab96e5”, Composites of nanostructured porous silicon and silver (nPSi-Ag) have attracted great attention due to the wide spectrum of applications in fields such as microelectronics, photonics, photocatalysis and bioengineering, Among the different methods for the fabrication of nanostructured composite materials, dip and spin-coating are simple, versatile, and cost-effective bottom-up technologies to provide functional coatings. In that sense, we aimed at fabricating nPSi-Ag composite layers. Using nPSi layers with pore diameter of 30 nm, two types of thin-film techniques were systematically compared: cyclic dip-coating (CDC) and cyclic spin-coating (CSC). CDC technique formed a mix of granular and flake-like structures of metallic Ag, and CSC method favored the synthesis of flake-like structures with Ag and Ag2O phases. Flakes obtained by CDC and CSC presented a width of 110 nm and 70 nm, respectively. Particles also showed a nanostructure surface with features around 25 nm. According to the results of EDX and RBS, integration of Ag into nPSi was better achieved using the CDC technique. SERS peaks related to chitosan adsorbed on Ag nanostructures were enhanced, especially in the nPSi-Ag composite layers fabricated by CSC compared to CDC, which was confirmed by FTDT simulations. These results show that CDC and CSC produce different nPSi-Ag composite layers for potential applications in bioengineering and photonics, This work was financially supported by Fondo Nacional de Desarrollo Científico y Tecnológico FONDECYT–Chile (grant number 11180395), FONDEQUIP–Chile (project 160152)

In the present work, the fabrication of hybrid porous silicon/green synthetized Ag microparticles was shown and the potential use as carriers for Ag nanoparticles and drug delivery was explored. Hybrid microparticles were fabricated by incorporating green synthetized Ag nanoparticles into porous silicon matrix. The main physicochemical characteristics of the hybrid systems were studied by several techniques including UV-vis spectroscopy, TEM, SEM, XRD and XPS. The toxicology of these hybrid systems was investigated by cell viability, MTT, and comet assays. In addition, the possibility to aggregate different drug to use as drug delivery system was demonstrated by using florfenicol as drug model, due to its importance in salmon industry. The experimental results showed the potential to use these hybrid systems as carries for drug delivery in salmon industry.

La formación de nanopartículas de quitosano mediante el método de gelación iónica tiene un alto potencial para la carga, transporte y liberación controlada de moléculas. Es un método sencillo y las nanopartículas presentan buena absorción, estabilidad, biocompatibilidad y baja toxicidad. El florfenicol es uno de los antibióticos más utilizados en la industria acuícola y es administrado mezclado con el alimento en altas concentraciones, lo cual genera problemas de dosis efectivas y de residuos no deseados. De esta manera, la síntesis de nanopartículas de quitosano (Q) cargadas con florfenicol podría otorgar ventajas a la hora de proteger, transportar y liberar de forma controlada el fármaco en peces de interés económico. En el presente estudio se sintetizaron nanopartículas de quitosano y tripolifosfato de sodio (TPP) con y sin florfenicol para evaluar su carga efectiva y liberación. Los resultados obtenidos con espectrometría FTIR corroboran la formación de las nanopartículas de Q-TPP con los cambios observados en los patrones de espectros infrarojo entre el quitosano matriz y las nanopartículas sintetizadas. Las nanopartículas de Q-TPP pueden cargar entre 48 y 50% de florfenicol en su interior. El ensayo de liberación in vitro del antibiótico mostró una liberación controlada y estable en el tiempo en condiciones de pH ácido y temperatura controlada de 15° C de hasta 10 días. Finalmente, se muestra que las nanopartículas de Q-TPP tienen potencial para atrapar y liberar de forma controlada el fármaco evaluado., The formation of nanoparticles of chitosan by the ionic gelation method has a high potential for loading, transport and controlled release of molecules. It is a simple method and the nanoparticles have good absorption, stability, biocompatibility and low toxicity. Florfenicol is one of the most used antibiotics in the aquaculture industry and is administered mixed with the feed in high concentrations, which generates problems of effective doses and unwanted residues. In this way, the synthesis of chitosan (Q) nanoparticles loaded with florfenicol could provide advantages when it comes to protecting, transporting and releasing the drug in fish of economic interest in a controlled manner. In the present study, nanoparticles of chitosan and sodium tripolyphosphate (TPP) with and without florfenicol were synthesized to evaluate their effective loading and release. The results obtained with FTIR spectrometry corroborate the formation of the Q-TPP nanoparticles with the changes observed in the infrared spectra patterns between the matrix chitosan and the synthesized nanoparticles. Q-TPP nanoparticles can carry between 48 and 50% of florfenicol inside. The in vitro release assay of the antibiotic showed a controlled and stable release over time under conditions of acid pH and controlled temperature of 15 °C for up to 10 days. Finally, it is shown that the Q-TPP nanoparticles have the potential to trap and release the evaluated drug in a controlled manner.

The applications of nanoparticles continue to expand into areas as diverse as medicine, bioremediation, cosmetics, pharmacology and various industries, including agri-food production. The widespread use of nanoparticles has generated concerns given the impact these nanoparticles – mostly metal-based such as CuO, Ag, Au, CeO2, TiO2, ZnO, Co, and Pt - could be having on plants. Some of the most studied variables are plant growth, development, production of biomass, and ultimately oxidative stress and photosynthesis. A systematic appraisal of information about the impact of nanoparticles on these processes is needed to enhance our understanding of the effects of metallic nanoparticles and oxides on the structure and function on the plant photosynthetic apparatus. Most nanoparticles studied, especially CuO and Ag, had a detrimental impact on the structure and function of the photosynthetic apparatus. Nanoparticles led to a decrease in concentration of photosynthetic pigments, especially chlorophyll, and disruption of grana and other malformations in chloroplasts. Regarding the functions of the photosynthetic apparatus, nanoparticles were associated with a decrease in the photosynthetic efficiency of photosystem II and decreased net photosynthesis. However, CeO2 and TiO2 nanoparticles may have a positive effect on photosynthetic efficiency, mainly due to an increase in electron flow between the photosystems II and I in the Hill reaction, as well as an increase in Rubisco activity in the Calvin and Benson cycle. Nevertheless, the underlying mechanisms are poorly understood. The future mechanistic work needs to be aimed at characterizing the enhancing effect of nanoparticles on the active generation of ATP and NADPH, carbon fixation and its incorporation into primary molecules such as photo-assimilates.

Over the last few years, the green synthesis of nanoparticles (NPs) using plant extracts has emerged as a promising methodology for the fabrication of metallic NPs (especially silver, copper, and gold NPs), as it involves an easy, fast, low-cost, and environmentally friendly bioprocess. However, many factors affect the sizes and morphologies of NPs biosynthesized by this method, including the nature of the plant extract, among others. Therefore, the green synthesis of metal NPs with defined stability, size, and morphology distribution remains under evaluation. In the present study, we propose aqueous extracts from the endemic-medicinal plant Budleja globosa (“Matico”) as an efficient bioproduct for the green synthesis of silver NPs (AgNPs). Experimental results indicate that room temperature, low concentrations of leaf extracts of B. globosa, and silver nitrate salt were sufficient to biosynthesize AgNPs with uniform size (16 nm) and shape distribution (spherical).

Propolis is widely recognized for its various therapeutic properties. These are attributed to its rich composition in polyphenols, which exhibit multiple biological properties (e.g., antioxidant, anti-inflammatory, anti-angiogenic). Despite its multiple benefits, oral administration of polyphenols results in low bioavailability at the action site. An alternative to face this problem is the use of biomaterials at nano-micro scale due to its high versatility as carriers and delivery systems of various drugs and biomolecules. The aim of this work is to determine if nPSi-&beta, CD microparticles are a suitable material for the load and controlled release of caffeic acid (CA) and pinocembrin (Pin), two of the main components of a Chilean propolis with anti-atherogenic and anti-angiogenic activity. Polyphenols and nPSi-&beta, CD microparticles cytocompatibility studies were carried out with human umbilical vein endothelial cells (HUVECs). Results from physicochemical characterization demonstrated nPSi-&beta, CD microparticles successfully retained and controlled release CA and Pin. Furthermore, nPSi-&beta, CD microparticles presented cytocompatibility with HUVECs culture at concentrations of 0.25 mg/mL. These results suggest that nPSi-&beta, CD microparticles could safely be used as an alternate oral delivery system to improve controlled release and bioavailability of CA or Pin&mdash, and eventually other polyphenols&mdash, thus enhancing its therapeutic effect for the treatment of different diseases.

Oxidized hyaluronic acid cross-linked with adipic acid dihydrazide (oxi-HA/ADH) forms an injectable and biocompatible hydrogel suitable for treatment of musculoskeletal diseases and for drug delivery applications. In that sense, nanoporous silicon (nPSi) can be combined with biopolymers, such as oxi-HA/ADH hydrogel, to display new characteristics, which are not exhibited by the individual constituents alone. Under this context, in this work nPSi microparticles at concentrations from 0.1% to 1% m/v were embedded into oxi-HA/ADH hydrogel to improve its mechanical stability and enhance its control over drug release kinetics using Rose Bengal (RB) as a model drug because its cytotoxic effect in different cancer cell lines and tumors has been previously reported. Our results showed, for both compressive force and stress strength tests, that oxi-HA/ADH hydrogel with 1% nPSi microparticles doubled the values of control samples. Moreover, samples of oxi-HA/ADH with nPSi microparticles improved RB release kinetics control over pure oxi-HA/ADH hydrogel. Finally, the cell viability of nPSi microparticles embedded into oxi-HA/ADH hydrogel was confirmed using fibroblasts, This work was financially supported by FONDECYT–Chile (grant number 11180395), CONICYT PFCHA/DOCTORADO/2017-21172001 (Nelson Naveas) and CNPq 140924/2017-5 (Carla França). We thank Fig. 8. A) Cytotoxicity of nPSi microparticles. B) Cell viability of hydrogels. C.G. Franca ̧ et al. Microporous and Mesoporous Materials 310 (2021) 110634 11 Dr. Héctor Pesenti for providing the DRX facility (FONDEQUIP–Chile, project 160152), and Dr. Luis Sanhueza for optical measurements of UVVis spectroscopy

Green synthesis of nanoparticles (NPs) from plant extracts have emerged as a promising methodology for the fabrication of metallic NPs, as it involves an easy, fast, low-cost, and environmentally friendly bioprocess. In the present study, we propose aqueous extracts from the endemic-medicinal plant Peumus boldus (“Boldo”) as an easy, fast, low-cost, and efficient bioproduct for the green synthesis of silver NPs (AgNPs). Our results indicate that room temperature conditions, short reaction time (only 3 h), low concentrations (1%) of leaf extracts of P. boldus, and silver nitrate salts (2 mM) were sufficient to biosynthesize AgNPs in a uniform size (18 nm) and shape distribution (spherical). In addition, stable and pure AgNPs were obtained in this process at the same time.

Titanium dioxide nanoparticles (TiO2NPs) generally have positive effects on growth and physiological parameters in plants, but their impacts on photosynthesis and antioxidant system are poorly understood. This work aimed to assess the effects of TiO2 NPs on photosynthetic performance and antioxidant system in Raphanus sativus L. plants. Treatments consisted of TiO2 NPs and microparticles (μPs) applied foliarly by increasing doses from 10 to 1500 mg L−1, using deionized water as a control. As expected, Ti concentration in leaf tissue increased concomitant with the applied dose, being higher in μPs than NPs. A transient increase in net photosynthetic rate (by about 50 %) and stomatal conductance were observed from 12 to 60 h after the beginning of NPs and μPs treatments compared to the control. These increments were independent of doses and particles size. The photochemical parameters were more influenced by the time than the doses, being electron transport rate (ETR) increased, and non photochemical quenching (NPQ) decreased. The instantaneous water use efficiency (WUEins) was 2-fold higher, and intrinsic water use efficiency (WUEint) was 70 % lower in the treated plants respect to the control. Total phenols concentration increased with increasing doses of NPs and μPs. It is suggested that TiO2 NPs and μPs had a transient positive impact on photosynthesis likely by diffusive effects, increasing the WUEins, and a slight activation of secondary metabolism.

Ordered mesoporous silicas were synthesized via cooperative self-assembly by using rice husk ash as silica source and P123 as main pore structure-directing agent. The incorporation of CTAB and BRIJ C10 as co-surfactant templates by different methods was investigated. Silicas with different pore size and mono-, bi- and trimodal porosity were obtained as a function of the co-surfactant used and the hydrolysis step performed. Low-angle XRD and TEM results confirmed the well-ordered pore structure of the synthesized silicas.

The relative easiness of fabrication of porous silicon, along with the possibility of precisely controlling its many unique properties, has made it a promising material for different applications in a wide variety of fields. In particular, this material is being actively studied for biological and medical applications. Within this context, in this chapter we review the key properties of porous silicon and the most significant applications of porous silicon in the fields of biosensing, bioimaging, drug delivery, and tissue engineering. The different processes commonly used to tailor the behavior of porous silicon for specific applications are also described in detail.

ZnO is probably one of the most studied oxides since ZnO nanostructures are a very rich family of nanomaterials with a broad variety of technological applications. Although several chemical techniques offer the possibility to obtain such ZnO nanostructures, here we show that the controlled modification of the zinc surface by low-energy O bombardment leads to the formation of core-shell Zn/ZnO nano-pyramidal arrays that suppress the reflection of light decreasing the reflectivity below 6% in the wavelength range of 300-900 nm. This controlled and scalable protocol opens the door to a broad range of possibilities for the use of ion bombardment to produce surface modifications for technological applications in the field of photoelectric devices and solar cells., The financial support by the Ministerio de Economía y Competitividad (MINECO) of Spain through the CONSOLIDER-Ingenio 2010 (CSD2008-00023) and MAT2015-69035-REDC programs is gratefully acknowledged.

ZnO is probably one of the most studied oxides since ZnO nanostructures are a very rich family of nanomaterials with a broad variety of technological applications. Although several chemical techniques offer the possibility to obtain such ZnO nanostructures, here we show that the controlled modification of the zinc surface by low-energy O

Cu-porous silicon (Cu-PS) composite materials consisting of nanosized Cu clusters preferentially grown on the surface of PS were fabricated by photoassisted deposition of Cu nanoparticles onto PS. Structural and chemical characterization of the Cu particles grown in the PS matrix has been carried out by synchrotron X-ray absorption spectroscopy, from which different reaction stages have been identified within the photoassisted reaction. In particular, it was found that the reduction of Cu occurs in three main phases: (a) Cu nucleates homogeneously in a few seconds over the surface of PS by a coupled red-ox reaction; (b) clusters grow by new reduced ions, which tend to oxidize the previously deposited Cu atoms making increasingly heterogeneous Cu clusters; and (c) a competitive process between nucleation of new clusters and cluster coalescence gives rise to a bulklike Cu thin film. It was determined that the structures formed in the first two phases display surface plasmon resonance, with band intensity and broadening consistent with the increasing heterogeneity of the clusters. The growth kinetics has been fitted to a Langmuir-Hill model. Following these results, a reaction model has been proposed to explain the mechanisms involved in the first stages of Cu clustering.

We present here a study on the viability of using gold nanoparticles infiltrated into porous silicon (PS) to develop plasmonic thin-film solar cells. For this objective, hybrid structures consisting of PS thin films and gold nanoparticles were fabricated. Optical, electrical and photocurrent measurements were carried out, from which it was found that the presence of gold nanoparticles in PS results in increased responsivity. This effect can be associated with increased light absorption and increased carrier collection efficiency.

In this study, we explore the selective culturing of human mesenchymal stem cells (hMSCs) on Si-based diffractive platforms. We demonstrate a single-step and flexible method for producing platforms on nanostructured porous silicon (nanoPS) based on the use of single pulses of an excimer laser to expose phase masks. The resulting patterns are typically 1D patterns formed by fringes or 2D patterns formed by circles. They are formed by alternate regions of almost unmodified nanoPS and regions where the nanoPS surface has melted and transformed into Si nanoparticles. The patterns are produced in relatively large areas (a few square millimeters) and can have a wide range of periodicities and aspect ratios. Direct binding, that is, with no previous functionalization of the pattern, alignment, and active polarization of hMSCs are explored. The results show the preferential direct binding of the hMSCs along the transformed regions whenever their width compares with the dimensions of the cells and they escape from patterns for smaller widths suggesting that the selectivity can be tailored through the pattern period. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.

A 3D silicon micromachining method based on proton beam writing combined with electrochemical anodization of p-type silicon enables fabrication of mid-infrared photonic crystals made of silicon and porous silicon. Here, example structures of silicon 1D and 2D photonic crystals are demonstrated. Progress and problems of fabricating 3D photonic crystals made of silicon are discussed. The strategy of fabricating photonic crystals purely made of porous silicon, and the characterization method of all these mid-infrared structures, are discussed. Due to the flexibility of this fabrication method, photonic devices and integrated photonic circuits may be built on a single chip, for which two 2D silicon photonic crystals with one on top of the other are demonstrated.

The typical large specific surface area and high reactivity of nanostructured porous silicon (nanoPS) make this material very suitable for the development of sensors. Moreover, its biocompatibility and biodegradability opens the way to the development of biosensors. As such, in this work the use of nanoPS in the field of electrical biosensing is explored. More specifically, nanoPS-based devices with Al/nanoPS/Al and Au-NiCr/nanoPS/Au-NiCr structures were fabricated for the electrical detection of glucose and Escherichia Coli bacteria at different concentrations. The experimental results show that the current-voltage characteristics of these symmetric metal/nanoPS/metal structures strongly depend on the presence/absence and concentration of species immobilized on the surface.

Nanostructured porous silicon (nanoPS) can be regarded as a complex network of silicon nanocrystals embedded in a porous matrix. NanoPS is fabricated by the electrochemical etch of silicon wafers in HF-based solutions. When crystalline Si is transformed into nanoPS, its intrinsic properties are altered owing to quantum confinement effects. That makes nanoPS an excellent candidate for the development of several applications in a broad range of fields including optoelectronics, photonics, and biomedicine. Surface micro- and nano-patterning is becoming an important way to enhance the performance of materials. In particular, nanoPS patterns have been proposed for the fabrication of photonic devices, high-sensitivity sensors, etc. Different techniques have been used for the fabrication of patterns on nanoPS including microstructuring the crystalline silicon substrate before the electrochemical etching process, dry soft lithography, stamp pressing, etc. However, none of these methods has the capability to offer flex-ibility in the pattern design in a time-efficient process, in large areas, and in a single step pro-cess. The present work reports on the fabrication of one- and two-dimensional platforms on nanoPS by phase-mask UV laser interference. This technique is a single-step and flexible approach to produce a large variety of patterns formed by alternate regions of almost untransformed nanoPS and regions where its surface has melted and transformed into Si nanoparticles. By changing the main experimental parameters such as nanoPS layer porosity, average pore size, laser fluence or pattern period, the properties of the resulting structures can be controlled. These patterns have been proved to be good candidates for such applications as sensing and for the development of biological platforms.

Silicon and porous silicon based photonic crystals are key aspects of photonic circuits with good compatibility with integrated circuits. Here a brief review is carried out on the fabrication of mid infrared photonic crystals using experimental processes of combining ion beam irradiation and electrochemical anodisation of silicon. Experimental processes have been developed to fabricate high aspect ratio trenches in porous silicon, high aspect ratio silicon pillars, buried channels in porous silicon, and multilevel freestanding silicon wires. These structures have the potential to be used for photonic crystals. Several 2D, quasi-3D and 3D mid infrared photonic crystals in porous silicon and silicon have been designed and fabricated.

In the present work, the photo-acoustic emission from nanostructured copper/porous silicon hybrid systems was studied. Copper nanoparticles were grown by photo-assisted electroless deposition on crystalline silicon and nanostructured porous silicon (nanoPS). Both the optical and photo-acoustic responses from these systems were determined. The experimental results show a remarkable increase in the photo-acoustic intensity when copper nanoparticles are incorporated to the porous structure. The results thus suggest that the Cu/nanoPS hybrid systems are suitable candidates for several applications in the field of thermoplasmonics, including the development of sound-emitting devices of great efficiency.