PDMS biofunctionalization study for the development of a microfluidic device: Application to salivary cortisol

The authors acknowledge to Sofia Neves from ICVS for her help in the antibodies selection.

Discrimination of Brazilian propolis according to the seasoning using chemometrics and machine learning based on UV-Vis scanning data

Propolis is a chemically complex biomass produced by honeybees (Apis mellifera) from plant resins added of salivary enzymes, beeswax, and pollen. The biological activities described for propolis were also identified for donor plants resin, but a big challenge for the standardization of the chemical composition and biological effects of propolis remains on a better understanding of the influence of seasonality on the chemical constituents of that raw material. Since propolis quality depends, among other variables, on the local flora which is strongly influenced by (a)biotic factors over the seasons, to unravel the harvest season effect on the propolis chemical profile is an issue of recognized importance. For that, fast, cheap, and robust analytical techniques seem to be the best choice for large scale quality control processes in the most demanding markets, e.g., human health applications. For that, UV-Visible (UV-Vis) scanning spectrophotometry of hydroalcoholic extracts (HE) of seventy-three propolis samples, collected over the seasons in 2014 (summer, spring, autumn, and winter) and 2015 (summer and autumn) in Southern Brazil was adopted. Further machine learning and chemometrics techniques were applied to the UV-Vis dataset aiming to gain insights as to the seasonality effect on the claimed chemical heterogeneity of propolis samples determined by changes in the flora of the geographic region under study. Descriptive and classification models were built following a chemometric approach, i.e. principal component analysis (PCA) and hierarchical clustering analysis (HCA) supported by scripts written in the R language. The UV-Vis profiles associated with chemometric analysis allowed identifying a typical pattern in propolis samples collected in the summer. Importantly, the discrimination based on PCA could be improved by using the dataset of the fingerprint region of phenolic compounds ( = 280-400m), suggesting that besides the biological activities of those secondary metabolites, they also play a relevant role for the discrimination and classification of that complex matrix through bioinformatics tools. Finally, a series of machine learning approaches, e.g., partial least square-discriminant analysis (PLS-DA), k-Nearest Neighbors (kNN), and Decision Trees showed to be complementary to PCA and HCA, allowing to obtain relevant information as to the sample discrimination.

Cortisol, family coping and burden in informal caregivers of addicts

This study focuses on the prospective mediation role of family coping between burden and cortisol levels in informal caregivers of addicts as well as on the feasible use of two different ways to analyse the salivary cortisol levels. Participants were 120 Portuguese informal caregivers of addicts. The cortisol samples were collected at awakening, 45 minutes later and after a 30 minute presentation of images taken from the International Affective Picture System. Family coping and caregiver burden were measured using the Portuguese versions of the Caregiver Reaction Assessment, and the Family Crisis Oriented Personal Evaluation Scale. Cortisol samples were collected in salivettes and the results were computed in order to determine the Area Under the Curve scores (AUCg, AUCi). Results found family coping to be negatively correlated with burden and AUCg levels (i.e. overall intensity) and positively correlated with either AUCg and AUCi (i.e. change over time). The mediation model revealed that family coping was a partial mediator in the relationship between the burden and AUCg levels. Therefore, Family Coping appears to be an essential variable in understanding the stress response and should be considered in further studies and interventions. In addition, the use of two different formulas for calculating cortisol levels provided important new information concerning the relationship between cortisol, burden and family coping. It seems that burden has a more profound effect on the overall intensity of the neuroendocrine response to caregiver stress and not so much on the sensitivity of the system.

Influence of saliva and mucin on the adhesion of Candida oral clinical isolates

Objectives: This research work intends to clarify the role of artificial saliva, in particularly the role of mucin, a salivary protein, on the surface properties and adhesion ability of Candida spp. oral clinical isolates to abiotic surfaces. Methods: Four oral clinical isolates of Candida spp. were used: two Candida albicans strains (AC; AM) and two Candida parapsilosis strains (AD; AM2). The strains were isolated from patients using oral prosthesis. The microorganisms were cultured in the absence or presence of mucin and artificial saliva, and their adhesion to an abiotic surface (coated with mucin and artificial saliva) was evaluated. Results: The presence of mucin per se onto the abiotic surface decreased the adhesion of all strains, although the combination of mucin with artificial saliva had reduced this effect. No direct correlation between adhesion and the surface free energies of adhesion of the microorganisms was found. Significance: Candida spp. were human commensal microorganisms that became pathogenic when the host immune defenses were compromised. Medical devices were colonized by Candida spp. particularly, oral prostheses, which might lead to the degradation of the prostheses and systemic infections. The salivary secretions that constantly cover the oral cavity influenced Candida spp. adhesion process. Therefore, it was important to understand the interactions between Candida spp., salivary proteins and the characteristic of oral prosthesis when developing materials for oral prostheses.

Localization of MCT2 at peroxisomes is associated with malignant transformation in prostate cancer

Previous studies on monocarboxylate transporters expression in prostate cancer (PCa) have shown that monocarboxylate transporter 2 (MCT2) was clearly overexpressed in prostate malignant glands, pointing it out as a putative biomarker for PCa. However, its localization and possible role in PCa cells remained unclear. In this study, we demonstrate that MCT2 localizes mainly at peroxisomes in PCa cells and is able to take advantage of the peroxisomal transport machinery by interacting with Pex19. We have also shown an increase in MCT2 expression from non-malignant to malignant cells that was directly correlated with its peroxisomal localization. Upon analysis of the expression of several peroxisomal ß-oxidation proteins in PIN lesions and PCa cells from a large variety of human prostate samples, we suggest that MCT2 presence at peroxisomes is related to an increase in ß -oxidation levels which may be crucial for malignant transformation. Our results present novel evidence that may not only contribute to the study of PCa development mechanisms but also pinpoint novel targets for cancer therapy.

Silk fibroin based multifunctional materials

Silk fibroin is a commonly available natural biopolymer produced in specialized glands of arthropods, such as silkworms or spiders, scorpions, mites, bees and flies. This biopolymer has a long history of use in textile production and also as sutures or treatment of skin wounds. Silk fibroin has been increasingly explored in other areas of biomedical science where we can find a higher morphological diversification of silk biomaterials like films, electrospun fibers, 3D porous scaffolds or nanoparticles. In recent years it has been demonstrated that fibroin is an excellent material for active components in optical devices. This new application opens the way towards the development of multifunctional optoelectronic devices, which in perspective can be made fully biocompatible and eventually bioresorbable. Moreover, fibroin can be added to other biocomponents in order to modify the biomaterial properties leading to optimized and total different functions. These improvements can go from higher cell adhesion in tissue engineering or enhanced optical transparency, smoothness or flexibility in optoelectronic devices. The tuning and completely understanding of silk fibers physicochemical properties and interaction with other elements are of crucial importance for the improvement of already existent silk-based materials and the basis for the development of new products.

Lithium-doped silk fibroin films for application in electrochromic devices

Silk fibroin (SF) is a commonly available natural biopolymer produced in specialized glands of arthropods, with a long history of use in textile production and also in health cares. The exceptional intrinsic properties of these fibers, such as self-assembly, machinability, biocompatibility, biodegradation or non-toxicity, offer a wide range of exciting opportunities [1]. It has long been recognized that silk can be a rich source of inspiration for designing new materials with tailored properties, enhanced performance and high added value for targeted applications, opening exciting new prospects in the domain of materials science and related technological fields, including bio-friendly integration, miniaturization and multifunctionalization. In recent years it has been demonstrated that fibroin is an excellent material for active components in optics and photonics devices. Progress in new technological fields such as optics, photonics and electronics are emerging [2,3]. The incorporation of polymer electrolytes as components of various devices (advanced batteries, smart windows, displays and supercapacitors) offers significant advantages with respect to traditional electrolytes, including enhanced reliability and improved safety. SF films are particularly attractive in this context. They have near-perfect transparency across the VIS range, surface flatness (together with outstanding mechanical robustness), ability to replicate patterned substrates and their thickness may be easily tailored from a few nanometers to hundreds of micrometers through spin-casting of a silk solution into subtract. Moreover, fibroin can be added to other biocomponents or salts in order to modify the biomaterial properties leading to optimized and total different functions. Preliminary tests performed with a prototype electrochromic device (ECD) incorporating SF films doped with lithium triflate and lithium tetrafluoroborate (LiTFSI and LiBF4, respectively) as electrolyte and WO3 as cathodic electrochromic layer, are extremely encouraging. Aiming to evaluate the performance of the ion conducting SF membranes doped with LiTFSI and LiBF4 (SF-Li), small ECDs with glass/ITO/WO3/SF-Li/CeO2-TiO2/ITO/glass configuration were assembled and characterized. The device exhibited, after 4500 cycles, the insertion of charge at -3.0 V reached –1.1 mC.cm-2 in 15 s. After 4500 cycles the window glass-staining, glass/ITO/WO3/Fibrin-Li salts electrolyte/CeO2-TiO2/ITO/glass configuration was reversible and featured a T  8 % at λ = 686 nm

Evaluation of bioactivities of a propolis sample (Gerês) of Portuguese origin

Dissertação de mestrado em Genética Molecular