Reducing Inert Materials for Optimal Cell-Cell and Cell-Matrix Interactions within Microphysiological Systems.

In the pursuit of achieving a more realistic in vitro simulation of human biological tissues, microfluidics has emerged as a promising technology. Organ-on-a-chip (OoC) devices, a product of this technology, contain miniature tissues within microfluidic chips, aiming to closely mimic the in vivo environment. However, a notable drawback is the presence of inert material between compartments, hindering complete contact between biological tissues. Current membranes, often made of PDMS or plastic materials, prevent full interaction between cell types and nutrients. Furthermore, their non-physiological mechanical properties and composition may induce unexpected cell responses. Therefore, it is essential to minimize the contact area between cells and the inert materials while simultaneously maximizing the direct contact between cells and matrices in different compartments. The main objective of this work is to minimize inert materials within the microfluidic chip while preserving proper cellular distribution. Two microfluidic devices were designed, each with a specific focus on maximizing direct cell-matrix or cell-cell interactions. The first chip, designed to increase direct cell-cell interactions, incorporates a nylon mesh with regular pores of 150 microns. The second chip minimizes interference from inert materials, thereby aiming to increase direct cell-matrix contact. It features an inert membrane with optimized macropores of 1 mm of diameter for collagen hydrogel deposition. Biological validation of both devices has been conducted through the implementation of cell migration and cell-to-cell interaction assays, as well as the development of epithelia, from isolated cells or spheroids. This endeavor contributes to the advancement of microfluidic technology, aimed at enhancing the precision and biological relevance of in vitro simulations in pursuit of more biomimetic models.

Tuneable hydrogel patterns in pillarless microfluidic devices.

Organ-on-chip (OOC) technology has recently emerged as a powerful tool to mimic physiological or pathophysiological conditions through cell culture in microfluidic devices. One of its main goals is bypassing animal testing and encouraging more personalized medicine. The recent incorporation of hydrogels as 3D scaffolds into microfluidic devices has changed biomedical research since they provide a biomimetic extracellular matrix to recreate tissue architectures. However, this technology presents some drawbacks such as the necessity for physical structures as pillars to confine these hydrogels, as well as the difficulty in reaching different shapes and patterns to create convoluted gradients or more realistic biological structures. In addition, pillars can also interfere with the fluid flow, altering the local shear forces and, therefore, modifying the mechanical environment in the OOC model. In this work, we present a methodology based on a plasma surface treatment that allows building cell culture chambers with abutment-free patterns capable of producing precise shear stress distributions. Therefore, pillarless devices with arbitrary geometries are needed to obtain more versatile, reliable, and biomimetic experimental models. Through computational simulation studies, these shear stress changes are demonstrated in different designed and fabricated geometries. To prove the versatility of this new technique, a blood-brain barrier model has been recreated, achieving an uninterrupted endothelial barrier that emulates part of the neurovascular network of the brain. Finally, we developed a new technology that could avoid the limitations mentioned above, allowing the development of biomimetic OOC models with complex and adaptable geometries, with cell-to-cell contact if required, and where fluid flow and shear stress conditions could be controlled.

Surface modifications of COP-based microfluidic devices for improved immobilisation of hydrogel proteins: long-term 3D culture with contractile cell types and ischaemia model.

The tissue microenvironment plays a crucial role in tissue homeostasis and disease progression. However, the in vitro simulation has been limited by the lack of adequate biomimetic models in the last decades. Thanks to the advent of microfluidic technology for cell culture applications, these complex microenvironments can be recreated by combining hydrogels, cells and microfluidic devices. Nevertheless, this advance has several limitations. When cultured in three-dimensional (3D) hydrogels inside microfluidic devices, contractile cells may exert forces that eventually collapse the 3D structure. Disrupting the compartmentalisation creates an obstacle to long-term or highly cell-concentrated assays, which are extremely relevant for multiple applications such as fibrosis or ischaemia. Therefore, we tested surface treatments on cyclic-olefin polymer-based microfluidic devices (COP-MD) to promote the immobilisation of collagen as a 3D matrix protein. Thus, we compared three surface treatments in COP devices for culturing human cardiac fibroblasts (HCF) embedded in collagen hydrogels. We determined the immobilisation efficiency of collagen hydrogel by quantifying the hydrogel transversal area within the devices at the studied time points. Altogether, our results indicated that surface modification with polyacrylic acid photografting (PAA-PG) of COP-MD is the most effective treatment to avoid the quick collapse of collagen hydrogels. As a proof-of-concept experiment, and taking advantage of the low-gas permeability properties of COP-MD, we studied the application of PAA-PG pre-treatment to generate a self-induced ischaemia model. Different necrotic core sizes were developed depending on initial HCF density seeding with no noticeable gel collapse. We conclude that PAA-PG allows long-term culture, gradient generation and necrotic core formation of contractile cell types such as myofibroblasts. This novel approach will pave the way for new relevant in vitro co-culture models where fibroblasts play a key role such as wound healing, tumour microenvironment and ischaemia within microfluidic devices.

A Label Free Disposable Device for Rapid Isolation of Rare Tumor Cells from Blood by Ultrasounds.

The use of blood samples as liquid biopsy is a label-free method for cancer diagnosis that offers benefits over traditional invasive biopsy techniques. Cell sorting by acoustic waves offers a means to separate rare cells from blood samples based on their physical properties in a label-free, contactless and biocompatible manner. Herein, we describe a flow-through separation approach that provides an efficient separation of tumor cells (TCs) from white blood cells (WBCs) in a microfluidic device, "THINUS-Chip" (Thin-Ultrasonic-Separator-Chip), actuated by ultrasounds. We introduce for the first time the concept of plate acoustic waves (PAW) applied to acoustophoresis as a new strategy. It lies in the geometrical chip design: different to other microseparators based on either bulk acoustic waves (BAW) or surface waves (SAW, SSAW and tSAW), it allows the use of polymeric materials without restrictions in the frequency of work. We demonstrate its ability to perform high-throughput isolation of TCs from WBCs, allowing a recovery rate of 84% ± 8% of TCs with a purity higher than 80% and combined viability of 85% at a flow rate of 80 µL/min (4.8 mL/h). The THINUS-Chip performs cell fractionation with low-cost manufacturing processes, opening the door to possible easy printing fabrication.

Multiwell capillarity-based microfluidic device for the study of 3D tumour tissue-2D endothelium interactions and drug screening in co-culture models.

The tumour microenvironment is very complex, and essential in tumour development and drug resistance. The endothelium is critical in the tumour microenvironment: it provides nutrients and oxygen to the tumour and is essential for systemic drug delivery. Therefore, we report a simple, user-friendly microfluidic device for co-culture of a 3D breast tumour model and a 2D endothelium model for cross-talk and drug delivery studies. First, we demonstrated the endothelium was functional, whereas the tumour model exhibited in vivo features, e.g., oxygen gradients and preferential proliferation of cells with better access to nutrients and oxygen. Next, we observed the endothelium structure lost its integrity in the co-culture. Following this, we evaluated two drug formulations of TRAIL (TNF-related apoptosis inducing ligand): soluble and anchored to a LUV (large unilamellar vesicle). Both diffused through the endothelium, LUV-TRAIL being more efficient in killing tumour cells, showing no effect on the integrity of endothelium. Overall, we have developed a simple capillary force-based microfluidic device for 2D and 3D cell co-cultures. Our device allows high-throughput approaches, patterning different cell types and generating gradients without specialised equipment. We anticipate this microfluidic device will facilitate drug screening in a relevant microenvironment thanks to its simple, effective and user-friendly operation.

Glioblastoma on a microfluidic chip: Generating pseudopalisades and enhancing aggressiveness through blood vessel obstruction events.

Background: Glioblastoma (GBM) is one of the most lethal tumor types. Hypercellular regions, named pseudopalisades, are characteristic in these tumors and have been hypothesized to be waves of migrating glioblastoma cells. These "waves" of cells are thought to be induced by oxygen and nutrient depletion caused by tumor-induced blood vessel occlusion. Although the universal presence of these structures in GBM tumors suggests that they may play an instrumental role in GBM's spread and invasion, the recreation of these structures in vitro has remained challenging. Methods: Here we present a new microfluidic model of GBM that mimics the dynamics of pseudopalisade formation. To do this, we embedded U-251 MG cells within a collagen hydrogel in a custom-designed microfluidic device. By controlling the medium flow through lateral microchannels, we can mimic and control blood-vessel obstruction events associated with this disease. Results: Through the use of this new system, we show that nutrient and oxygen starvation triggers a strong migratory process leading to pseudopalisade generation in vitro. These results validate the hypothesis of pseudopalisade formation and show an excellent agreement with a systems-biology model based on a hypoxia-driven phenomenon. Conclusions: This paper shows the potential of microfluidic devices as advanced artificial systems capable of modeling in vivo nutrient and oxygen gradients during tumor evolution.

Study of the Chemotactic Response of Multicellular Spheroids in a Microfluidic Device.

We report the first application of a microfluidic device to observe chemotactic migration in multicellular spheroids. A microfluidic device was designed comprising a central microchamber and two lateral channels through which reagents can be introduced. Multicellular spheroids were embedded in collagen and introduced to the microchamber. A gradient of fetal bovine serum (FBS) was established across the central chamber by addition of growth media containing serum into one of the lateral channels. We observe that spheroids of oral squamous carcinoma cells OSC-19 invade collectively in the direction of the gradient of FBS. This invasion is more directional and aggressive than that observed for individual cells in the same experimental setup. In contrast to spheroids of OSC-19, U87-MG multicellular spheroids migrate as individual cells. A study of the exposure of spheroids to the chemoattractant shows that the rate of diffusion into the spheroid is slow and thus, the chemoattractant wave engulfs the spheroid before diffusing through it.

The role of N-glycosylation in kiwi allergy.

The physical, biochemical, and immunological characteristics of plant allergens have been widely studied, but no definite conclusion has been reached about what actually makes a protein an allergen. In this sense, N-glycosylation is an exclusive characteristic of plant allergens not present in mammals and it could be implied in allergenic sensitization. With this aim, we evaluated and compared the allergenic activity of the protein fraction and the N-glycan fraction of the thaumatin-like protein and the main kiwi allergen, Act d 2. The natural allergen, Act d 2, was deglycosylated by trifluoromethanesulfonic acid treatment; the N-glycan fraction was obtained by extended treatment with proteinase K. N-glycan- and protein- fractions were recognized by specific IgE of kiwi-allergic patients. By contrast, the sugar moiety showed a reduced capacity to activate basophils and T cells, but not dendritic cells derived from patients' monocytes. Related to this, the production of cytokines such as IL6 and IL10 was increased by the incubation of dendritic cells with sugar moiety. Thus, the sugar moiety plays a significant role in sensitization, inducing the activation of antigen-presenting cells, but it is the protein fraction that is responsible for the allergic reactions.

Alt a 1 from Alternaria interacts with PR5 thaumatin-like proteins.

Alt a 1 is a protein found in Alternaria alternata spores related to virulence and pathogenicity and considered to be responsible for chronic asthma in children. We found that spores of Alternaria inoculated on the outer surface of kiwifruits did not develop hyphae. Nevertheless, the expression of Alt a 1 gene was upregulated, and the protein was detected in the pulp where it co-localized with kiwi PR5. Pull-down assays demonstrated experimentally that the two proteins interact in such a way that Alt a 1 inhibits the enzymatic activity of PR5. These results are relevant not only for plant defense, but also for human health as patients with chronic asthma could suffer from an allergic reaction when they eat fruit contaminated with Alternaria.

Development of a three-dimensional cell culture system based on microfluidics for nuclear magnetic resonance and optical monitoring.

A new microfluidic cell culture device compatible with real-time nuclear magnetic resonance (NMR) is presented here. The intended application is the long-term monitoring of 3D cell cultures by several techniques. The system has been designed to fit inside commercially available NMR equipment to obtain maximum readout resolution when working with small samples. Moreover, the microfluidic device integrates a fibre-optic-based sensor to monitor parameters such as oxygen, pH, or temperature during NMR monitoring, and it also allows the use of optical microscopy techniques such as confocal fluorescence microscopy. This manuscript reports the initial trials culturing neurospheres inside the microchamber of this device and the preliminary images and spatially localised spectra obtained by NMR. The images show the presence of a necrotic area in the interior of the neurospheres, as is frequently observed in histological preparations; this phenomenon appears whenever the distance between the cells and fresh nutrients impairs the diffusion of oxygen. Moreover, the spectra acquired in a volume of 8 nl inside the neurosphere show an accumulation of lactate and lipids, which are indicative of anoxic conditions. Additionally, a basis for general temperature control and monitoring and a graphical control software have been developed and are also described. The complete platform will allow biomedical assays of therapeutic agents to be performed in the early phases of therapeutic development. Thus, small quantities of drugs or advanced nanodevices may be studied long-term under simulated living conditions that mimic the flow and distribution of nutrients.

Condición post-quirúrgica relacionada al cumplimiento del protocolo de procedimientos de exodoncia en unidades comunitarias de salud familiar, SIBASI centro octubre 2013-enero 2014 / Post-surgical condition related to compliance with the protocol of extraction procedures in community family health units, SIBASI center October 2013-January 2014

Objetivo: Evaluar el cumplimiento del protocolo de procedimientos de exodoncia y su relación en la evolución de la condición post-quirúrgica en Unidades Comunitarias de Salud Familiar del SIBASI CENTRO. Metodología: Es una investigación de tipo descriptiva asociativa, en la que se observó la aplicación del protocolo de exodoncia simple; y su relación con las condiciones post operatorias que pueda presentar el paciente. La población fue de 88 pacientes de 20-59 años; durante el periodo octubre 2013-enero 2014. Para recolectar datos se utilizaron dos guías de observación una dirigida al cumplimiento en gran medida, buena medida y en escasa medida del protocolo de exodoncia y la segunda guía a la condición post-quirúrgica del paciente en buen estado y mal estado. Como prueba estadística se utilizó el Chi Cuadrado para determinar la relación de las variables. Resultados: El 71.6% de las exodoncias se realizaron bajo un cumplimiento del protocolo de exodoncia en gran medida, 28.4% bajo un cumplimiento del protocolo de exodoncia en buena medida. En relación a la condición postquirúrgica de 88 pacientes que asistieron a la realización de tratamientos de exodoncias a 25 se les aplicó un protocolo en buena medida, 10 presentaron una condición post-quirúrgica en mal estado y 15 pacientes llegaron en buen estado; a 63 pacientes que se les ejecutó un protocolo de exodoncia en gran medida, 18 llegaron en mal estado y 45 en buen estado. Conclusiones: Ningún odontólogo ejecutó el protocolo de exodoncia en escasa medida. Determinando que el riesgo de tener una condición postquirúrgica en mal estado es 1.42 veces más en los que recibieron un protocolo en buena medida (regular), que el que lo recibió en gran medida, siendo este último a quien se le aplicó entre un 90 a 100 % el protocolo vigente en el Ministerio de Salud. Por lo que estos resultados indican que, no solamente aplicar en gran medida el protocolo de exodoncia simple basta para tener una buena condición post-quirúrgica. Ya que este podría depender de otros factores.

Objective: To evaluate the compliance of the procedures of dental extraction protocol and its relationship with evolution of post-surgical condition in Family Health Community Centers of SIBASI Centro. Methodology: This is a descriptive-associative investigation, in which studies the application of the of the simple dental extraction protocol; and its relationship with the post-surgical condition presented by patient. The sample of this investigation was conformed by 88 patients from 20 to 59 years old; during the period from October, 2013 to January, 2014. To collect the data there were used two observation format documents, one of these led to determine great extent, large extent and small extent of dental extraction protocol accomplishment and the second instrument guide led to check the post-surgical condition of the patient in good condition and bad condition. It was used the Chi-squared to determinethe connection of the variables. Results: 71.6% of the dental extraction were executed under the compliance of the dental extraction protocol in great extent, 28.4% was executed under compliance of the dental extraction protocol in large extent. In relation to the post-surgical condition of the 88 patients who attended to be treated with simple dental extraction, to 25 of them was applied a protocol in large extent, 10 of them presented a bad post-surgical condition and 15 a good condition; to 63 patient whose was applied a dental extraction protocol in great extent, 18 presented bad condition and 45 a good condition. Conclusions: Not dentist executed the dental extraction protocol in small extent. Having established that the risk of suffering bad post-surgical condition is 1.4 times more in those who were treated with a protocol in large extent, in comparison to those who was applied between 90 to 100% of Ministerio de Salud's current protocol. In addition data were obtained (p>0.05) does not confirm that a patient who was exposed to a proper implementation of the dental extraction protocol will have impact in the post- surgical condition in good or bad condition, for the ultimate result could depend on other factors not included in this study

The impact of atmospheric pollutants on the prevalence of atopic eczema in 6-7-year-old schoolchildren in Spain; ISAAC Phase III.

Atopic Eczema (AE) is a chronic inflammatory skin disease that affects children and adults, and alters quality of life with a high morbidity rate and severe economic burden. The objective of the present work was to analyse specific atmospheric pollutants (O3, NO, PM10 and SO2) affecting the prevalence of diagnosed AE and its symptoms among 6-7-year-old schoolchildren.The participants included 21311 schoolchildren aged 6-7 years from 8 Spanish regions, whose parents completed the ISAAC Phase III questionnaire to ascertain AE diagnosis and symptoms. The mean levels (µg/m3) of O3, NO, PM10 (particles 10 micrometers or less in diameter) and SO2 were determined in each geographical area. Participating in this study.According to these mean levels, three levels of exposure to each pollutant were considered: level 1 (percentiles 0-25); level 2 (percentiles 26-74); level 3 (percentiles 75-100). Exposure to O3 was associated with increased prevalence of rashes (exposure level 2, Odds Ratio (OR): 1.22, 95% Confidence Interval (95%CI): 1.02-1.45; level 3 OR: 1.33, 95%CI: 1.10-1.61) and diagnosed AE (level 2, OR: 1.27, 95%CI: 1.17-1.39; level 3 OR: 1.27, 95%CI: 1.15-1.41). An association was found between the level of NO and a drop in the prevalence of diagnosed AE (exposure level 2, OR: 0.88, 95%CI: 0.81-0.95; level 3 OR: 0.85, 95%CI: 0.74-0.97). There was also an association between the highest exposure level to PM10 and a reduced prevalence of rashes (level 3 OR: 0.42, 95%CI: 0.22-0.81) and diagnosed AE (level 3 OR: 0.53, 95%CI: 0.38-0.75). Future studies into exposure to O3 and its relationship with allergic diseases may be conducted in order to prevent this association.

Is acetaminophen use associated with atopic eczema and other allergic diseases in adolescents?

Atopic Eczema (AE) is a chronic inflammatory skin disease that affects children and adults, and alters quality of life. Previous studies have suggested several socio-demographic and environmental factors related to the prevalence of AE and other allergic diseases, including acetaminophen use. In the present study, we report the rates of isolated AE, AE associated with asthma and AE associated with rhinitis among 13- to 14-year-old Spanish adolescents and the level of association of these conditions with the use of acetaminophen. We analyzed Spanish data from a cross-sectional Phase 3 study within ISAAC. A total of 28,717 adolescents completed the Phase 3 written questionnaire by answering questions for acetaminophen use and on asthma, rhinitis and AE symptoms.We observed an association between acetaminophen use and AE among the adolescents who had used acetaminophen in the previous month. Furthermore, the prevalence rate increased with the number of allergic processes: for AE alone, the adjusted Prevalence Ratio (aPR) was 1.81 and for AE associated with rhinitis or with asthma, aPRs were 2.20 and 3.03, respectively.We conclude that acetaminophen use in childhood may be an important factor associated with development and/or maintenance of AE and other allergic diseases.

Prevalence of asthma symptoms in schoolchildren, and climate in west European countries: an ecologic study.

The aim of the present study was to estimate the associations between the prevalence of asthma symptoms in schoolchildren and meteorological variables in west European countries that participated in the International Study of Asthma and Allergies in Children (ISAAC), Phase III 1997-2003. An ecologic study was carried out. The prevalence of asthma was obtained from this study from 48 centers in 14 countries, and meteorological variables from those stations closest to ISAAC centers, together with other socioeconomic and health care variables. Multilevel mixed-effects linear regression models were used. For schoolchildren aged 6-7 years, the prevalence rate of asthma decreased with an increase in mean annual sunshine hours, showed a positive association with rainy weather, and warm temperature, and a negative one with relative humidity and physician density (PD). Current wheeze prevalence was stronger in autumn/winter seasons and decreased with increasing PD. Severe current wheeze decreased with PD. For schoolchildren aged 13-14 years, the prevalence rates of asthma and current wheeze increased with rainy weather, and these rates decreased with increased PD. Current wheeze, as measured by a video questionnaire, was inversely associated with sunny weather, and nurse density. Severe current wheeze prevalence was stronger during autumn/winter seasons, decreased with PD, and indoor chlorinated public swimming pool density, and increased with rainy weather. Meteorological factors, including sunny and rainy weather, and PD may have some effect on the prevalence rates of asthma symptoms in children from west European countries.

Graph based study of allergen cross-reactivity of plant lipid transfer proteins (LTPs) using microarray in a multicenter study.

The study of cross-reactivity in allergy is key to both understanding. the allergic response of many patients and providing them with a rational treatment In the present study, protein microarrays and a co-sensitization graph approach were used in conjunction with an allergen microarray immunoassay. This enabled us to include a wide number of proteins and a large number of patients, and to study sensitization profiles among members of the LTP family. Fourteen LTPs from the most frequent plant food-induced allergies in the geographical area studied were printed into a microarray specifically designed for this research. 212 patients with fruit allergy and 117 food-tolerant pollen allergic subjects were recruited from seven regions of Spain with different pollen profiles, and their sera were tested with allergen microarray. This approach has proven itself to be a good tool to study cross-reactivity between members of LTP family, and could become a useful strategy to analyze other families of allergens.

Atopic dermatitis and indoor use of energy sources in cooking and heating appliances.

BACKGROUND: Atopic dermatitis (AD) prevalence has considerably increased worldwide in recent years. Studying indoor environments is particularly relevant, especially in industrialised countries where many people spend 80% of their time at home, particularly children. This study is aimed to identify the potential association between AD and the energy source (biomass, gas and electricity) used for cooking and domestic heating in a Spanish schoolchildren population. METHODS: As part of the ISAAC (International Study of Asthma and Allergies in Childhood) phase III study, a cross-sectional population-based survey was conducted with 21,355 6-to-7-year-old children from 8 Spanish ISAAC centres. AD prevalence, environmental risk factors and the use of domestic heating/cooking devices were assessed using the validated ISAAC questionnaire. Crude and adjusted odds ratios (cOR, aOR) and 95% confidence intervals (CIs) were obtained. A logistic regression analysis was performed (Chi-square test, p-value < 0.05). RESULTS: It was found that the use of biomass systems gave the highest cORs, but only electric cookers showed a significant cOR of 1.14 (95% CI: 1.01-1.27). When the geographical area and the mother's educational level were included in the logistic model, the obtained aOR values differed moderately from the initial cORs. Electric heating was the only type which obtained a significant aOR (1.13; 95% CI: 1.00-1.27). Finally, the model with all selected confounding variables (sex, BMI, number of siblings, mother's educational level, smoking habits of parents, truck traffic and geographical area), showed aOR values which were very similar to those obtained in the previous adjusted logistic analysis. None of the results was statistically significant, but the use of electric heating showed an aOR close to significance (1.14; 95% CI: 0.99-1.31). CONCLUSION: In our study population, no statistically significant associations were found between the type of indoor energy sources used and the presence of AD.

The involvement of thaumatin-like proteins in plant food cross-reactivity: a multicenter study using a specific protein microarray.

Cross-reactivity of plant foods is an important phenomenon in allergy, with geographical variations with respect to the number and prevalence of the allergens involved in this process, whose complexity requires detailed studies. We have addressed the role of thaumatin-like proteins (TLPs) in cross-reactivity between fruit and pollen allergies. A representative panel of 16 purified TLPs was printed onto an allergen microarray. The proteins selected belonged to the sources most frequently associated with peach allergy in representative regions of Spain. Sera from two groups of well characterized patients, one with allergy to Rosaceae fruit (FAG) and another against pollens but tolerant to food-plant allergens (PAG), were obtained from seven geographical areas with different environmental pollen profiles. Cross-reactivity between members of this family was demonstrated by inhibition assays. Only 6 out of 16 purified TLPs showed noticeable allergenic activity in the studied populations. Pru p 2.0201, the peach TLP (41%), chestnut TLP (24%) and plane pollen TLP (22%) proved to be allergens of probable relevance to fruit allergy, being mainly associated with pollen sensitization, and strongly linked to specific geographical areas such as Barcelona, Bilbao, the Canary Islands and Madrid. The patients exhibited >50% positive response to Pru p 2.0201 and to chestnut TLP in these specific areas. Therefore, their recognition patterns were associated with the geographical area, suggesting a role for pollen in the sensitization of these allergens. Finally, the co-sensitizations of patients considering pairs of TLP allergens were analyzed by using the co-sensitization graph associated with an allergen microarray immunoassay. Our data indicate that TLPs are significant allergens in plant food allergy and should be considered when diagnosing and treating pollen-food allergy.

Computational study of ligand binding in lipid transfer proteins: Structures, interfaces, and free energies of protein-lipid complexes.

Plant nonspecific lipid transfer proteins (nsLTPs) bind a wide variety of lipids, which allows them to perform disparate functions. Recent reports on their multifunctionality in plant growth processes have posed new questions on the versatile binding abilities of these proteins. The lack of binding specificity has been customarily explained in qualitative terms on the basis of a supposed structural flexibility and nonspecificity of hydrophobic protein-ligand interactions. We present here a computational study of protein-ligand complexes formed between five nsLTPs and seven lipids bound in two different ways in every receptor protein. After optimizing geometries in molecular dynamics calculations, we computed Poisson-Boltzmann electrostatic potentials, solvation energies, properties of the protein-ligand interfaces, and estimates of binding free energies of the resulting complexes. Our results provide the first quantitative information on the ligand abilities of nsLTPs, shed new light into protein-lipid interactions, and reveal new features which supplement commonly held assumptions on their lack of binding specificity.

Nanophotonic lab-on-a-chip platforms including novel bimodal interferometers, microfluidics and grating couplers.

One of the main limitations for achieving truly lab-on-a-chip (LOC) devices for point-of-care diagnosis is the incorporation of the "on-chip" detection. Indeed, most of the state-of-the-art LOC devices usually require complex read-out instrumentation, losing the main advantages of portability and simplicity. In this context, we present our last advances towards the achievement of a portable and label-free LOC platform with highly sensitive "on-chip" detection by using nanophotonic biosensors. Bimodal waveguide interferometers fabricated by standard silicon processes have been integrated with sub-micronic grating couplers for efficient light in-coupling, showing a phase resolution of 6.6 × 10(-4)× 2π rad and a limit of detection of 3.3 × 10(-7) refractive index unit (RIU) in bulk. A 3D network of SU-8 polymer microfluidics monolithically assembled at the wafer-level was included, ensuring perfect sealing and compact packaging. To overcome some of the drawbacks inherent to interferometric read-outs, a novel all-optical wavelength modulation system has been implemented, providing a linear response and a direct read-out of the phase variation. Sensitivity, specificity and reproducibility of the wavelength modulated BiMW sensor has been demonstrated through the label-free immunodetection of the human hormone hTSH at picomolar level using a reliable biofunctionalization process.

LocaPep: localization of epitopes on protein surfaces using peptides from phage display libraries.

The use of peptides from a phage display library selected by binding to a given antibody is a widespread technique to probe epitopes of antigenic proteins. However, the identification of interaction sites mimicked by these peptides on the antigen surface is a difficult task. LocaPep is a computer program developed to localize epitopes using a new clusters algorithm that focuses on protein surface properties. The program is constructed with the aim of providing a flexible computational tool for predicting the location of epitopes on protein structures. As a first set of testing results, the localization of epitope regions in eight different antigenic proteins for which experimental data on their antibody interactions exist is correctly identified by LocaPep. These results represent a disparate sample of biologically different systems. The program is freely available at http://atenea.montes.upm.es.