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A novel water-stable 2D Copper-Imidazolate Framework (2DCIF) exhibits outstanding electrocatalytic activity for the oxygen reduction reaction without the need for calcination. These 2DCIFs have been successfully used as air electrodes in Zn–air batteries.

We report on the preparation and characterization of two dimensional (2D) films of (S,S,P)-1 and (R,R,M)-1 ortho-oligophenylene ethylene (o-OPE) enantiomers presenting high values of circularly polarized luminescence (CPL). The amphiphilic character of these two molecules allows a precise 2D self-assembly at the air/water interface and an efficient transfer onto a glass solid support. The morphological and chiroptical characterization of the solid supports after the transfer of 1, 8, 16 and 32 Langmuir films of (S,S,P)-1 and (R,R,M)-1 has been carried out. The strong chiroptical values of these monomers allow reliable ECD measurements to be obtained after a single transfer, with ECD values increasing as the number of transferred films increases. The semi-liquid behavior of the monomers on the solid substrate allows CPL measurements free of photoselection artifacts that show values similar to those obtained in solution and independent of monomer concentration. All these properties have allowed us to develop the first simple organic molecule (SOM)-based chiroptical barcoding presenting positive and negative regions as a proof of concept., Spanish Ministry of Science and Innovation (AEI, Spain) PID2020-112744GB-I00 Ministry of Science and Innovation, Spain (MICINN) Spanish Government MCIN/AIE, FSE "El FSE invierte en tu futuro" in Spain, FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento/Proyecto PID2020-113059GB-C21/AEI PRE2021-097546 FPU16/02597 P20_00162

Fluid interfaces provide an advanced platform for directed self-assembly of organic composites and formation of supramolecular polymers (SPs). Intermolecular interactions govern the supramolecular polymerization processes, with hydrogen bonding (H-bonding) as a key interaction in supramolecular chemistry and biology. Two purposefully designed supra-amphiphiles for assessing the role of H-bonding were designed and their supramolecular polymerization (SP) at the air/water interface was compared. H-bonding was confirmed by in situ experimental and computational techniques as the required intermolecular interaction for attaining SPs with well-defined molecular arrangement. Control of H-bonding as opposite to traditionally considered interactions, e.g., π-π stacking is proposed as a successful strategy for SP at fluid interfaces.

Embargado hasta 09/04/2023 Polymersomes and related self-assembled nanostructures displaying Aggregation-Induced Emission (AIE) are highly relevant for plenty of applications in imaging, biology and functional devices. Experimentally simple, scalable and universal strategies for on-demand self-assembly of polymers rendering well-defined nanostructures are highly desirable. A purposefully designed combination of amphiphilic block copolymers including tunable lengths of hydrophilic polyethylene glycol (PEGm) and hydrophobic AIE polymer poly(tetraphenylethylene-trimethylenecarbonate) (P(TPE-TMC)n) has been studied at the air/liquid interface. The unique 2D assembly properties have been analyzed by thermodynamic measurements, UV-vis reflection spectroscopy and photoluminescence in combination with molecular dynamics simulations. The (PEG)m-b-P(TPE-TMC)n monolayers formed tunable 2D nanostructures self-assembled on demand by adjusting the available surface area. Tuning of the PEG length allows to modification of the area per polymer molecule at the air/liquid interface. Molecular detail on the arrangement of the polymer molecules and relevant molecular interactions has been convincingly described. AIE fluorescence at the air/liquid interface has been successfully achieved by the (PEG)m-b-P(TPE-TMC)n nanostructures. An experimentally simple 2D to 3D transition allowed to obtain 3D polymersomes in solution. This work suggests that engineered amphiphilic polymers for AIE may be suitable for selective 2D and 3D self-assembly for imaging and technological applications.

The design of sustainable procedures for the preparation of cobalt/carbon-based materials as an anode for hydrogen fuel production through electrocatalytic water splitting has attracted much interest in the last few years. Herein, a novel environmentally friendly approach for the development of stable and active catalysts for the oxygen evolution reaction (OER) is reported. In detail, the methodology aimed at developing a sequence of composites having a low cobalt loading ( MW/US > MW > conventional heating, with the best sample requiring an overpotential of 365 mV to deliver a current density of 10 mA cm_2 and a Tafel slope of 58 mV dec_1.

Embargado hasta 15/02/2023 The assembly of atomically dispersed iron–nitrogen (FeN4) sites into graphitic structures is a promising approach for sustainable production of bifunctional electrocatalysts for the oxygen electroreduction (ORR) and oxygen evolution (OER) reactions. In addition, single-atom FeN4 sites at the edges of carbon substrates provide higher electrocatalytic performance than those in plane. Unfortunately, the conventional high-temperature pyrolysis method does not allow the generation of edge-enriched FeN4 single-atom sites. Herein, a novel low-temperature and solvent-free mechanochemical synthesis based on the use of dipyridylpyridazine (dppz) functionalized multilayer graphene as a starting material is proposed for precisely engineered location of these FeN4 active sites at the edges. After careful characterization of these dppz-based materials, the ORR and OER electrocatalytic performance was investigated, demonstrating the efficient formation of FeN4 sites at the edges as well as their excellent bifunctional behavior for the ORR and OER. This work paves the way for the development of sustainable approaches for the generation of edge-enriched FeN4 single atom sites on multilayer graphene structures.

Fmoc-dipeptides appear as highly relevant building blocks in smart hydrogels and nanovehicles for biological applications. The interactions of the Fmocdipeptides with the cell membrane determine the efficiency of the nanomaterials based on the Fmoc-dipeptides’ internalization of nanovehicles for drug delivery. Here, we aim to understand the interplay of the interactions between the Fmoc-dipeptides and a phospholipid surface as a function of the amino acid sequence. The DMPA (1,2-dimyristoyl-snglycero- 3-phosphate) phospholipid in Langmuir monolayers was used as a model cell surface. A set of seven derivatives of Fmoc-dipeptides with a broad range of hydrophobicity were included. Mixed monolayers composed of DMPA/Fmoc-dipeptides in an equimolar ratio were built and characterized in situ at the air/water interface. Surface pressure−molecular area isotherms (π−A), Brewster angle microscopy (BAM), and UV−vis reflection spectroscopy (ΔR) were combined to provide a holistic picture of the interactions of the Fmoc-dipeptide with the phospholipid molecules. An increase in the hydrophobicity led to enhanced interaction of the Fmoc-dipeptide and DMPA molecules. The compression of the mixed monolayer could displace a significant fraction of the Fmoc-dipeptide from the monolayer. High hydrophobicity promoted self-assembly of the Fmoc-dipeptides over interaction with the phospholipid surface. The interplay of these two phenomena was analyzed as a function of the amino acid sequence of the Fmoc-dipeptides. The toxicity effect of Fmoc-FF could be observed and detailed at the molecular level. This study suggests that the adjustment of the hydrophobicity of the Fmoc-dipeptides within a defined range might optimize their efficiency for interaction with the lipid membranes. A semiquantitative guide for the chemical design of Fmoc-dipeptides for biological applications is proposed herein.

Incorporation of plasmonic metal nanoparticles (NPs) into the multilayered architecture of perovskite solar cells (PSCs) has been a recurrent strategy to enhance the performance of the photovoltaic devices from the early development of this technology. However, the specific photophysical interactions between the metal NPs and the hybrid halide perovskites are still not completely understood. Herein, we investigate the influence of Au NPs on the photoluminescence (PL) signal of a thin layer of the CH3NH3PbI3 hybrid perovskite. Core-shell Au@SiO2 NPs with tunable thickness of the SiO2 shell were used to adjust the interaction distance between the plasmonic NPs and the perovskite layer. A complete quenching of the PL signal in the presence of the Au NPs is measured together with a gradual recovery of the PL intensity at thicker thickness of the SiO2 shell. A nanometal surface energy transfer (NSET) model is employed to reasonably fit the experimental quenching efficiency. Thus, the energy transfer deactivation is revealed as a detrimental process occurring in the PSCs since it funnels the photon energy into the non-active excited state of the Au NPs. This work indicates that tuning the distance between the plasmonic NPs and the perovskite materials by a silica shell may be a simple and straightforward strategy for further improving the efficiency of the PSCs.

Embargado hasta 30/11/2023 The term “innovation” is core to modern science and society with respect to novelty, creation and added value, yet it is also a source of misunderstandings. We aim herein at the clarification of the different approaches to innovation by establishing three general types: background, basic and applied innovations. The relation between the three concepts is also established. The exclusive relationship between innovation and market is put into question. The contradictory conceptions of innovation are also accompanied by complementary connotations that can enrich one to other. Finally, a transversal proposal to deal with “innovation” in different environments is presented.

Pathogenic bacteria have the ability to develop antibiotic resistance mechanisms. Their action consists mainly in the production of bacterial enzymes that inactivate antibiotics or the appearance of modifications that prevent the arrival of the drug at the target point or the alteration of the target point itself, becoming a growing problem for health systems. Chitosan&ndash, gold nanoparticles (Cs-AuNPs) have been shown as effective bactericidal materials avoiding damage to human cells. In this work, Cs-AuNPs were synthesized using chitosan as the reducing agent, and a systematic analysis of the influence of the synthesis parameters on the size and zeta potential of the Cs-AuNPs and their UV-vis spectra was carried out. We used a simulation model to characterize the interaction of chitosan with bacterial membranes, using a symmetric charged bilayer and two different chitosan models with different degrees of the chitosan amine protonation as a function of pH, with the aim to elucidate the antibacterial mechanism involving the cell wall disruption. The Cs-AuNP antibacterial activity was evaluated to check the simulation model.

Proteins and peptide fragments are highly relevant building blocks in self-assembly for nanostructures with plenty of applications. Intrinsically disordered proteins (IDPs) and protein regions (IDRs) are defined by the absence of a well-defined secondary structure, yet IDPs/IDRs show a significant biological activity. Experimental techniques and computational modelling procedures for the characterization of IDPs/IDRs are discussed. Directed self-assembly of IDPs/IDRs allows reaching a large variety of nanostructures. Hybrid materials based on the derivatives of IDPs/IDRs show a promising performance as alternative biocides and nanodrugs. Cell mimicking, in vivo compartmentalization, and bone regeneration are demonstrated for IDPs/IDRs in biotechnological applications. The exciting possibilities of IDPs/IDRs in nanotechnology with relevant biological applications are shown.

The oxygen evolution reaction (OER) plays a key role in the water splitting process and a high energy conversion efficiency is essential for the definitive advance of hydrogen-based technologies. Unfortunately, the green and sustainable development of electrocatalysts for water oxidation is nowadays a real challenge. Herein, a successful mechanochemical method is proposed for the synthesis of a novel hemoglobin (Hb) modified Co

The physicochemical properties of the metal-ion battery anodes display a key role in the full behavior and electrochemical performance of energy storage devices. Novel ion battery anode materials (NIBAMs) are attracting a growing attention due to the capacity limitation of the classic graphite anodes, which provide low specific- and rate-capacity, and safety issues. Nevertheless, the electrochemical performance of NIBAMs such as the capacity, cyclability, rate capability, voltage profiles, and safety are strongly dependent on the structural and morphological evolution, phase transformation, ion diffusion, and electrode/electrolyte interface reconstruction during charge–discharge cycling and storage. In-depth understanding of the electrochemical process of NIBAMs is essential for optimizing their preparation and application conditions, and exploring NIBAMs. Traditional electroanalytical methods, such as charge/discharge, cyclic voltammetry, and electrochemical impedance spectroscopy are utilized to research the capacity, resistance, rate capability and cyclability of NIBAMs. Recently, rapid progress and development in hyphenated techniques by coupling with X-ray, electron, scanning probe, optics, neutron, and magnetic techniques have provided extensive insights into the nature of structural evolution and morphological changes of NIBAMs, and electrode/electrolyte interface. In this review, a comprehensive overview of both classical electroanalytical methods and advanced electroanalytical hyphenated techniques for studying the NIBAMs is provided.

Here, we report the synthesis and characterization of crystalline C60 nanomaterials and their applications as bifunctional water splitting catalysts. The shapes of the resulting materials were tuned via a solvent engineering approach to form rhombic-shaped nanosheets and nanotubes with hexagonal close packed-crystal structures. The as-synthesized materials exhibited suitable properties as bifunctional catalysts for HER and ORR reactions surpassing by far the electrocatalytic activity of commercially available amorphous C60. The C60 nanotubes displayed the most efficient catalytic performance with a small onset potential of −0.13 V vs. RHE and ultrahigh electrochemical stability properties towards the generation of molecular hydrogen. Additionally, the rotating-disk electrode measurements revealed that the oxygen reduction mechanism at the nanotube electrochemical surfaces followed an effective four-electron pathway. The improved catalytic activity was attributed to the enhanced local electric fields at the high curvature surfaces.

The oxygen evolution reaction (OER) plays a key role in the water splitting process and a high energy conversion efficiency is essential for the definitive advance of hydrogen-based technologies. Unfortunately, the green and sustainable development of electrocatalysts for water oxidation is nowadays a real challenge. Herein, a successful mechanochemical method is proposed for the synthesis of a novel hemoglobin (Hb) modified Co3O4/g-C3N4 composite nanomaterial. The controlled incorporation of cobalt entities as well as Hb functionalization, without affecting the g-C3N4 nanoarchitecture, was evaluated using different physicochemical techniques, such as X-ray diffraction, N2-physisorption, scanning electron microscopy, UV-visible spectroscopy and X-ray photoelectron spectroscopy. The beneficial effect of the resulting ternary bioconjugate together with the influence of the temperature and light irradiation was investigated by electrochemical analysis. At 60 °C and under light exposition, this electrocatalyst requires an overpotential of 370 mV to deliver a current density of 10 mA·cm−2, showing a Tafel slope of 66 mV·dec−1 and outstanding long-term stability for 600 OER cycles. This work paves a way for the controlled fabrication of multidimensional and multifunctional bio-electrocatalysts.

Embargado hasta 01/12/2022 Biomineralization is of paramount importance for life on Earth. The delicate balance of physicochemical interac-tions at the interface between organic and inorganic matter during all stages of biomineralization resembles anextremelyhighcomplexity.The coordination ofthis sophisticatedbiologicalmachineryand physicochemical sce-narios is certainly a wonderful show of nature. Understanding of the biomineralization processes is still far fromcomplete. The recent advances in biomineralization research from the Colloid and Interface Science perspectiveare reviewed herein. The synergy between this twofields of research is demonstrated. The unique opportunitiesoffered by purposefully designedfluid interfaces, mainly Langmuir monolayers are presented. Biomedical appli-cations of biomineral-based nanostructures are discussed, showing their improved biocompatibility and on-demand delivery features. A brief guide to the array of state-of-the-art experimental techniques for unravelingthe mechanisms of biomineralization usingfluid interfaces is included. In summary, the fruitful and excitingcrossroad between Colloid and Interface Science with Biomineralization is exhibited.

Dipeptides self-assemble into supramolecular structures showing plenty of applications in the nanotechnology and biomedical fields. A set of Fmoc-dipeptides with different aminoacid sequences has been synthesized and their self-assembly at fluid interfaces has been assessed. The relevant molecular parameters for achieving an efficient 2D self-assembly process have been established. The selfassembled nanostructures of Fmoc-dipeptides displayed significant chirality and retained the chemical functionality of the aminoacids. The impact of the sequence on the final supramolecular structure has been evaluated in detail using in situ characterization techniques at air/water interfaces. This study provides a general route for the 2D self-assembly of Fmoc-dipeptides.

The ability to respond toward mechanical stimuli is a fundamental property of biological organisms at both the macroscopic and cellular levels, yet it has been considerably less observed in artificial supramolecular and colloidal homologues. An archetypal example in this regard is cellular mechanosensation, a process by which mechanical forces applied on the cell membrane are converted into biochemical or electrical signals through nanometer-scale changes in molecular conformations. In this article, we report an artificial gold nanoparticle (Au NP)−discrete π-conjugated molecule hybrid system that mimics the mechanical behavior of biological membranes and is able to self-assemble into colloidal gold nanoclusters or membranes in a controlled and reversible fashion by changing the concentration or the mechanical force (pressure) applied. This has been achieved by rational design of a small π-conjugated thiolated molecule that controls, to a great extent, the hierarchy levels involved in Au NP clustering by enabling reversible, cooperative non-covalent (π−π, solvophobic, and hydrogen bonding) interactions. In addition, the Au NP membranes have the ability to entrap and release aromatic guest molecules reversibly (Kb = 5.0 × 105 M−1 ) for several cycles when subjected to compression−expansion experiments, in close analogy to the behavior of cellular mechanosensitive channels. Not only does our hybrid system represent the first example of a reversible colloidal membrane, but it also can be controlled by a dynamic mechanical stimulus using a new supramolecular surface-pressure-controlled strategy. This approach holds great potential for the development of multiple colloidal assemblies within different research fields.

Amino acids including the Fmoc group (9-fluorenylmethyloxycarbonyl) are bioinspired molecules that display intriguing features in self-assembly and biological applications. The influence of a delicate chemical modification between Fmoc-F and Fmoc-Y on the interaction with a phospholipid surface was analyzed. Langmuir monolayers of the 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA) phospholipid were used to mimic the eukaryotic cell membrane. In situ Brewster angle microscopy and UV-vis reflection spectroscopy provided insights on the effect of the Fmoc-amino acid derivatives on the DMPA phospholipid. The formation of H-bonds between the Fmoc-Y and the DMPA molecules was assessed, demonstrating the crucial role of the hydroxyl group of Fmoc-Y in enhancing the interaction with biosurfaces.

A metal-free oxygen reduction reaction (ORR) electrocatalyst with outstanding performance was obtained through an easy and one-pot synthesis of hemoglobin functionalized fructose@graphene-oxide (GO) nanocomposites. The active pyridinic nitrogen sites of the highly unfolded proteins together with the excellent electronic properties of GO appears to be the main factors causing the improved electrocatalytic activity.

Cobalt is one of the most promising non‐noble metal as electrocatalyst for water oxidation. Herein, a highly stable silicon‐cobalt mixed oxide thin film with a porous columnar nanostructure is proposed as electrocatalyst for oxygen evolution reaction (OER). CoOx and CoxSiyOz layers with similar thickness were fabricated at room temperature by magnetron sputtering in a glancing angle configuration (MS‐GLAD) on tin‐doped indium oxide (ITO) substrates. After characterization, a comparative study of the electrocatalytic performance for OER of both layers was carried out. The excellent long‐term stability as electrocatalyst for OER of the porous CoxSiyOz thin film demonstrates that the presence of silicon on the mixed oxide network increases the mechanical stability of the Si/Co layer, whilst maintaining a considerable electrocatalytic response.

Fluorescent inorganic quantum dots are highly promising for biomedical applications as sensing and imaging agents. However, the low internalization of the quantum dots, as well as for most of the nanoparticles, by living cells is a critical issue which should be solved for success in translational research. In order to increase the internalization rate of inorganic CdSe/ZnS quantum dots, they were functionalized with a fluorinated organic ligand. The fluorinated quantum dots displayed an enhanced surface activity, leading to a significant cell uptake as demonstrated by in vitro experiments with HeLa cells. We combined the experimental and computational results of Langmuir monolayers of the DPPC phospholipid as a model cell membrane with in vitro experiments for analyzing the mechanism of internalization of the fluorinated CdSe/ZnS quantum dots. Surface pressure-molecular area isotherms suggested that the physical state of the DPPC molecules was greatly affected by the quantum dots. UV–vis reflection spectroscopy and Brewster Angle Microscopy as in situ experimental techniques further confirmed the significant surface concentration of quantum dots. The disruption of the ordering of the DPPC molecules was assessed. Computer simulations offered detailed insights in the interaction between the quantum dots and the phospholipid, pointing to a significant modification of the physical state of the hydrophobic region of the phospholipid molecules. This phenomenon appeared as the most relevant step in the internalization mechanism of the fluorinated quantum dots by cells. Thus, this work sheds light on the role of fluorine on the surface of inorganic nanoparticles for enhancing their cellular uptake.

Fuel cells stand out as among the most promising alternatives for non-sustainable fossil fuel based economy. Efficient electrocatalysts for the oxygen reduction reaction (ORR) are required for the mass application of fuel cells. Citrate-stabilized gold nanoparticles (AuNPs) are proposed as potentialdependent electrocatalysts for the ORR. AuNPs were synthesized by a green, reproducible, and easy scale-up method. After exhaustive characterization, the electrocatalytic activity of the resulting AuNPs was investigated in alkaline media. Static and dynamic electrochemical studies showed a core-size dependent tendency both for their potentials and intensities. For the first time ever, the hysteresis effect in the ORR profile over Au nanoelectrocatalysts is reported herein. In addition, the electrocatalytic efficiency was comparable to those obtained for Au clusters, suggesting the benefits of the citrate stabilizing agent on the electrocatalyst performance of nanomaterials based on noble metals for ORR. These results pave the way for the design of non-coated AuNPs as strong candidates for ORR.

Fluorescent nanoparticles, such as quantum dots, hold great potential for biomedical applications, mainly sensing and bioimaging. However, the inefficient cell uptake of some nanoparticles hampers their application in clinical practice. Here, the effect of the modification of the quantum dot surface with fluorinated ligands to increase their surface activity and, thus, enhance their cellular uptake was explored.

The oxygen reduction (ORR) and hydrogen evolution (HER) reactions are the most important cathodic processes involved in fuel cell and water splitting technologies, respectively. The development of bifunctional electrocatalyst materials plays a key role in the rapid advancement of these hydrogen-based renewable energy strategies. This work proposes citrate-stabilized gold nanoparticles (AuNPs) as a bifunctional electrocatalyst for ORR and HER. The capping ligand has a great influence on their resulting electrocatalytic performance. A simple ligand exchange method based on concentration gradients has been optimized. The surface structure of the different ligand-stabilized AuNPs was inferred by lead underpotential deposition (Pb-UPD). Static and dynamic electrochemical studies for both ORR and HER have been performed using different ligand-stabilized AuNPs as electrocatalysts, demonstrating that the citrate ligand confers the best performance. This work suggests that non-doped chemically synthesized AuNPs may be suitable as a bifunctional electrocatalyst in fuel cells and hydrogen production.

Plasmonic nanoparticles (NPs) are one of the most promising and studied inorganic nanomaterials for different biomedical applications. Plasmonic NPs have excellent biocompatibility, long-term stability against physical and chemical degradation, relevant optical properties, well-known synthesis methods and tuneable surface functionalities. Herein, we review recently reported bioconjugated plasmonic NPs using different chemical approaches and loading cargoes (such as drugs, genes, and proteins) for enhancement of transdermal delivery across biological tissues. The main aim is to understand the interaction of the complex skin structure with biomimetic plasmonic NPs. This knowledge is not only important in enhancing transdermal delivery of pharmaceutical formulations but also for controlling undesired skin penetration of industrial products, such as cosmetics, sunscreen formulations and any other mass-usage consumable that contains plasmonic NPs.

Monolayers of a cytosine-based nucleolipid (1,2-dipalmitoyl-sn-glycero-3-(cytidine diphosphate) (ammonium salt), CDP-DG) at basic subphase have been prepared at the air-water interface both in absence and presence of guanine. The formation of the complementary base pairing is demonstrated by combining surface experimental techniques, i.e., surface pressure (π)–area (A), Brewster angle microscopy (BAM), infrared spectroscopy (PM-IRRAS) and computer simulations. A folding of the cytosine-based nucleolipid molecules forming monolayer at the air-water interface occurs during the guanine recognition as absorbate host and is kept during several compression-expansion processes under set experimental conditions. The specificity between nitrogenous bases has been also registered. Finally, mixed monolayers of CDP-DG and a phospholipid (1,2-dimyristoyl-sn-glycero-3-phosphate (sodium salt), DMPA) has been studied and a molecular segregation of the DMPA molecules has been inferred by the additivity rule.

Janus gold nanoparticles are of high interest because they allow directed self-assembly and display plasmonic properties. We succeeded in coating gold nanoparticles with two different polymers that form a Janus shell. The spontaneous segregation of two immiscible polymers at the surface of the nanoparticles was verified by NOESY NMR and most importantly by electron microscopy analysis in two and three dimensions. The Janus structure is additionally shown to affect the aggregation behavior of the nanoparticles.

Materials scientists have performed exceptional accomplishments in the design of various types of materials that can be directly used for biomedical research. In particular, nanomaterials (including plasmonic nanoparticles) have become forefront scaffolds for designing bioactive materials. The application of such materials in biomedicine however requires a directed design providing actuation and stability in a particularly complex environment such as living organisms. Enhanced diagnostic tools for diseases such as cancer and HIV are pursued, and in this context nanoparticles offer exclusive physicochemical features for accurate biosensing, as well as actuation. We discuss the biosensing capabilities of plasmonic nanoparticles, in connection with SERS imaging. Novel therapies based on local drug delivery and photothermal therapy activated by nanoparticles are being explored. These applications are briefly discussed in this article, considering the actual biological problems faced by materials scientists and highlighting the beneficial interactions between materials science and biomedicine, which lead to novel routes in biomedical research and practice.

Interactions of paclitaxel (PTX) with models mimicking biological interfaces (lipid membranes and serum albumin, HSA) were investigated to test the hypothesis that the set of in vitro assays proposed can be used to predict some aspects of drug pharmacokinetics (PK). PTX membrane partitioning was studied by derivative spectrophotometry; PTX effect on membrane biophysics was evaluated by dynamic light scattering, fluorescence anisotropy, atomic force microscopy and synchrotron small/wide-angle X-ray scattering; PTX distribution/molecular orientation in membranes was assessed by steady-state/time-resolved fluorescence and computer simulations. PTX binding to HSA was studied by fluorescence quenching, derivative spectrophotometry and dynamic/electrophoretic light scattering. PTX high membrane partitioning is consistent with its efficacy crossing cellular membranes and its off-target distribution. PTX is closely located in the membrane phospholipids headgroups, also interacting with the hydrophobic chains, and causes a major distortion of the alignment of the membrane phospholipids, which, together with its fluidizing effect, justifies some of its cellular toxic effects. PTX binds strongly to HSA, which is consistent with its reduced distribution in target tissues and toxicity by bioaccumulation. In conclusion, the described set of biomimetic models and techniques has the potential for early prediction of PK issues, alerting for the required drug optimizations, potentially minimizing the number of animal tests used in the drug development process.

The combination of plasmonic nanoparticles and mesoporous materials is of much interest in applications such as sensing or catalysis. The production of such hybrid materials can be done in various ways, leading to different architectures. We present a comparative study of the SERS performance of different nanocomposite architectures comprising mesoporous TiO2 thin films and Au nanoparticles (NPs). The selection of TiO2 as mesoporous support material was based on its high chemical and mechanical stability. Au NPs of different sizes and shapes were placed at different locations of the composite and used as a plasmonic material compatible with the synthesis conditions of the mesoporous films, displaying a high chemical stability. Using p-nitrothiophenol as a molecular probe, we evaluated the performance toward surface-enhanced Raman scattering (SERS) sensing, on the basis of minimum acquisition time, spot-to-spot reproducibility, and limit of detection. The obtained results indicate that each platform features different sensing capabilities. While systems comprising Au NPs within the mesopores allow working with low acquisition times and present high signal uniformity, only a detection limit of micromolar was achieved. On the other hand, those systems made of branched Au NPs covered with mesoporous films require low acquisition times and can achieve detection limits as low as 10 pM, but signal uniformity is compromised. We propose that careful comparison of different SERS platforms based on Au NPs and mesoporous thin films will facilitate selecting an appropriate configuration for any desired application. Fil: Zalduendo, María Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina Fil: Langer, Judith. Centro de Investigación Cooperativa en Biomateriales; España Fil: Giner Casares, Juan J.. Centro de Investigación Cooperativa en Biomateriales; España Fil: Halac, Emilia B.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina Fil: Soler Illia, Galo Juan de Avila Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martin. Instituto de Nanosistemas; Argentina Fil: Liz Marzán, Luis M.. Centro de Investigación Cooperativa en Biomateriales; España. Basque Foundation for Science; España Fil: Angelome, Paula Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina

Unprecedented 3D nanobiosystems composed of recombinant CotA laccases and citrate-stabilised gold nanoparticles have been successfully achieved by an electrostatic self-assembly strategy. The bioelectrochemical reduction of O2 driven by CotA laccase at the spore coat was mimicked. Consequently key insights into its bioelectrocatalytic function were unravelled.

Polydiacetylene (PDA) and its derivatives are promising materials for applications in a vast number of fields, from organic electronics to biosensing. PDA is obtained through polymerization of diacetylene (DA) monomers, typically using UV irradiation. DA polymerization is a 1-4 addition reaction with both initiation and growth steps with topochemical control, leading to the "blue" polymer form as primary reaction product in bulk and at interfaces. Herein, the diacetylene monomer 10,12-pentacosadiynoic acid (DA) and the amphiphilic cationic N,N'-dioctadecylthiapentacarbocyanine (OTCC) have been used to build a mixed Langmuir monolayer. The presence of OTCC imposes a monolayer supramolecular structure instead of the typical trilayer of pure DA. Surface pressure, Brewster angle microscopy, and UV-vis reflection spectroscopy measurements, as well as computer simulations, have been used to assess in detail the supramolecular structure of the DA:OTCC Langmuir monolayer. Our experimental results indicate that the DA and OTCC molecules are sequentially arranged, with the two OTCC alkyl chains acting as spacing diacetylene units. Despite this configuration is expected to prevent photopolymerization of DA, the polymerization takes place without phase segregation, thus exclusively leading to the red polydiacetylene form. We propose a simple model for the initial formation of the "blue" or "red" PDA forms as a function of the relative orientation of the DA units. The structural insights and the proposed model concerning the supramolecular structure of the "blue" and "red" forms of the PDA are aimed at the understanding of the relation between the molecular and macroscopical features of PDAs.

International audience; Mixed Langmuir monolayers of 10,12-Pentacosadiynoic acid (DA) monomer and an amphiphilic Hemicyanine dye derivative have been formed at the air/water interface. Two derivatives of docosylpyridinium have been used, with either one included in the monolayer in 1:1 molar ratio. The DA monomers within the mixed monolayers have been polymerized in situ at the air/water interface. The crystalline structure of the monolayer and the kinetics of polymerization have been probed grazing incidence X-ray diffraction (GIXD). The polymerization of DA proceeds with no phase segregation, exclusively leading to the red polydiacetylene form. The kinetics of polymerization at the air/water interface has been monitored in situ by GIXD. The experimental results have been combined with Molecular Mechanics computer simulations, revealing that DA molecules are sequentially arranged with molecules of Hemicyanine dye in alternating rows. The hydrophobic chains of the dye molecules act as spacers between the DA monomers. Surprisingly, such molecular arrangement does not hinder the in situ photopolymerization of DA. The mechanism of polymerization of DA within the mixed Langmuir monolayers has been convincingly described in molecular detail. This approach for interfacial polymerization of DA holds great potential for optically active devices and nanostructures comprising self-assembled thin films based in polydiacetylene.

Photothermal therapy is proposed as a straightforward manner of killing cancer cells, which a plasmon field of gold nanoparticles is activated by incoming light resonance leading to a local increase of temperature. This photothermal effect is strongly dependent on the plasmonic features of the nanoparticles. Herein, we study the effect of the ion-mediated aggregation of citrate-capped small spherical gold nanoparticles on the plasmonic band and the photothermal performance. An intermediate value of ionic strength has been found to be optimum with respect to the photothermal capabilities of the gold nanoparticles.

The larger permeability of anions than cations through a lipid bilayer can be rationalized by the positive sign of the bilayer's dipole potential. That is, upon crossing the lipid headgroups toward the hydrocarbon chain region, the electrostatic potential increases by several hundred millivolts. We derive an analytic expression for the dipole potential of a single lipid layer using an electrostatic model that is based on an extended version of the linearized Poisson-Boltzmann theory. The model highlights the ability of the lipid headgroups to render the dipole potential positive by inducing an orientational ordering of the solvent molecules. The positive contribution of the solvent overcompensates the negative dipole potential due to the bare lipids. Our theoretical prediction compares accurately with measurements of the dipole potential that we have conducted for mixed anionic-zwitterionic lipid monolayers at the air-water interface.

Summary Biomedicine and clinical practice are entering a new era in which nanotechnology plays a core role. Plasmonic nanoparticles are most interesting in this regard, given the possibility of fine-tuning light-matter interactions at the nanoscale. The assembly of plasmonic nanoparticles onto planar ensembles with short interparticle distances leads to novel and unique optoelectronic features due to long-range plasmon coupling over large areas. These extended plasmonic structures incorporated onto substrates are proposed as advanced platforms to address biological and medical challenges. In this review we analyze the state-of-the art of plasmonic substrates with respect to their feasibility toward applications in biomedicine. We first consider plasmonic sensing of biomolecules and living cells, which is subsequently complemented by a further step toward the manipulation of living cells. We propose that plasmonic substrates will undoubtedly enrich biomedical practice for generalized use in the near future.

Physico-chemical processes at air/liquid interfaces are of paramount importance in nature. The Langmuir technique offers the possibility of forming a well-defined monolayer of amphiphilic molecules under study at the air/liquid interface, with a unique control of the area per molecule and other experimental conditions. Despite being a traditional technique in Colloid and Interface science, there is an ever growing interest in Langmuir studies. Herein, recent developing fields of research currently taking advantage of the Langmuir technique are reviewed, comprising the interfacial structure of: water, biomolecules and inorganic/organic hybrids. The good state of the Langmuir technique at present and the foreseeable increase of its usage are discussed.

Au nanotriangles display interesting nanoplasmonic features with potential application in various fields. However, such applications have been hindered by the lack of efficient synthetic methods yielding sufficient size and shape monodispersity, as well as by insufficient morphological stability. We present here a synthesis and purification protocol that efficiently addresses these issues. The size of the nanotriangles can be tuned within a wide range by simply changing the experimental parameters. The obtained monodispersity leads to extended self-assembly, not only on electron microscopy grids but also at the air-liquid interface, allowing transfer onto centimeter-size substrates. These extended monolayers show promising performance as surface-enhanced Raman scattering substrates, as demonstrated for thiophenol detection.

Chirality at interfaces is a relevant topic in nanoscience, as well as a key point for prebiotic chemistry. Mixed Langmuir monolayers, composed of the anionic phospholipid dimyristoyl phosphatidic acid (DMPA) and the cationic amphiphilic quinoline derivative 2-methyl-1-octadecylquinoline (MQ) have been built at the air-water interface. Both DMPA and MQ molecules are miscible, thus the equimolar mixture yields homogeneous monolayers completely. Chiral domains have been formed by this monolayer and observed in situ by Brewster angle microscopy (BAM). These chiral domains display a large array of shapes and sizes. The chirality of the monolayers has been confirmed by circular dichroism spectroscopy. The ordered aggregation of the quinoline group into large chiral supramolecular structures is proposed as the molecular origin of the observed chirality. Theoretical simulations using molecular mechanics confirm the strong trend of the quinoline group to form chiral aggregates. The great diversity in the size and shape of the chiral domains has been found to be strongly influenced by the competition between two nuclei growth mechanisms. An experimental procedure allowing a minimized growth through one of these mechanism is proposed, achieving a homogeneous distribution of ring-shaped domains. An overshoot in the pi-A isotherms of this mixed monolayer appears at an intermediate surface pressure. This overshoot is interpreted as being due to the large difference between the surface pressure which starts the nuclei formation, pi(crit) and the superficial pressure in which the nuclei can grow, pi(e). The rather small pi(e) value compared to pi(crit) observed for this system must be attributed to the molecular interactions involved in the mixed monolayer, which facilitate the incorporation of molecules in preformed nuclei.

Correction for ‘Tailoring the ORR and HER electrocatalytic performances of gold nanoparticles through metal–ligand interfaces’ by David Alba-Molina et al., J. Mater. Chem. A, 2019, DOI: 10.1039/c9ta05492h.