Papers by Ana Teresa Caldeira
Environmental Science and Pollution Research
International Journal of Food Microbiology
Applications of Coumarin Derivatives [Working Title]
Important areas such as environmental sciences, medicine, pharmacy, and cellular biology are depe... more Important areas such as environmental sciences, medicine, pharmacy, and cellular biology are dependent on very sensitive analytical techniques. One of the most common methodologies used for their bioanalytical purposes is the fluorescent labelling. The synthesis of new fluorophores and the great development of fluorescent-labelling techniques combined with the enormous technological advances in the field of fluorescence microscopy allowed to deepen the structural knowledge of biomolecules. This new organic fluorophores form covalent bonds with the sample to be analyzed, producing stable bioconjugates that show fluorescence in a wide range of wavelengths, depending on the label used. Coumarin derivatives represent one of the most important chemical classes of organic fluorescent materials being one of the most extensively investigated and commercially significant groups of organic fluorescent materials. In this chapter, it is reviewed the use of fluorescent coumarin derivatives and their application to labelling biomolecules. These fluorescent labels allow researchers to study, and understand, biomolecular assemblies that exhibit complex sensitivity and selectivity. Reactive fluorescent coumarin derivatives are actually widely used in labelling biomolecules as peptides, proteins, oligonucleotides, nucleic acids, and carbohydrates, among other biological molecules.
Microbial Biotechnology
Dekkera bruxellensis is the main reason for spoilage in the wine industry. It renders the product... more Dekkera bruxellensis is the main reason for spoilage in the wine industry. It renders the products unacceptable leading to large economic losses. Fluorescence In Situ Hybridization (FISH) technique has the potential for allowing its specific detection. Nevertheless, some experimental difficulties can be encountered when FISH technique is applied in the wine environment (e.g. matrix and cells' autofluorescence, fluorophore inadequate selection and probes' low specificity to the target organisms). An easy and fast in-suspension RNA-FISH procedure was applied for the first time for identifying D. bruxellensis in wine. A previously designed RNA-FISH probe to detect D. bruxellensis (26S D. brux.5.1) was used, and the matrix and cells' fluorescence interferences, the influence of three fluorophores in FISH performance and the probe specificity were evaluated. The results revealed that to apply RNA-FISH technique in the wine environment, a red-emitting fluorophore should be used. Good probe performance and specificity were achieved with 25% of formamide. The resulting RNA-FISH protocol was applied in wine samples artificially inoculated with D. bruxellensis. This spoilage microorganism was detected in wine at cell densities lower than those associated with phenolic off-flavours. Thus, the RNA-FISH procedure described in this work represents an advancement to facilitate early detection of the most dangerous wine spoilage yeast and, consequently, to reduce the economic losses caused by this yeast to the wine industry.
Color Research & Application
Applied Physics A, 2016
Easel paintings have been considered one of the most important art expressions, constituting toda... more Easel paintings have been considered one of the most important art expressions, constituting today outstanding works of art with important historic and cultural value. Unfortunately, due to the presence of several organic materials, these artworks have been affected by microbial contamination that among other factors can be responsible for different aesthetic and structural alterations. For this study, four easel paintings from the late nineteenth century by Giorgio Marini with evident chromatic and structural alterations due to biocontamination were analysed in order to better understand the materials used and the source of high microbial contamination within a focused conservation intervention process. For this end, both the biofilms and the painting materials were characterised by several analytical techniques. Fungal communities were found to prevail in areas with evident structural and aesthetic damages, which were confirmed by scanning electron microscopy analyses that allowed the observation of the fungal hyphae proliferation capacity. Energy-dispersive X-ray spectroscopy, μ-X-ray diffraction, μ-Raman, μ-FTIR and optical microscopy were used to further identify the painting materials. Immunological assays revealed the presence of a mixture of proteins of ovalbumin, collagen and casein, suggesting that the presence of these proteinaceous materials in these paintings is one of the main reasons of microbial biofilms appearance on the painting’s surface. These approaches contribute for a better knowledge of these artworks providing at the same time relevant information for the ongoing conservation–restoration intervention.
Environmental Science and Pollution Research, 2016
effective approach for confirming the selection of lipopeptides producer strains.
Advances in Microbiology, 2016
The science and technology interact with the art in several ways. Biotechnological coupled with a... more The science and technology interact with the art in several ways. Biotechnological coupled with analytical approaches can play an important role in protecting and preserving cultural heritage for future generations. Many microorganisms influenced by environmental conditions are the main responsible for biological contamination in built heritage. Biocides based on chemical compounds have been used to mitigate this problem. Thus, it is vitally important to develop proper remediation actions based on environmentally innocuous alternative. Bacillus specie is emerging as an optimistic alternative for built heritage treatment due to their capacity to produce secondary metabolites with antagonistic activities against many fungal pathogens. Therefore, the intent of this work was to access a rapid evaluation of antifungal potential of bioactive metabolites produced by Bacillus strains and simultaneously their characterization using spectroscopic (NMR) and chromatographic techniques (LC-ESI-MS). The high antifungal activity obtained for Bacillus sp. active compounds produced in this study confirms the great potential to suppress biodeteriogenic fungi growth on historical artworks. Additionally, the proposed methodology allowed to access bioactive metabolites produced without need of the laborious total previous isolation and could be used as a viable alternative to be employed for screening and production of new green biocides.
Journal of Agricultural Science and Technology, 2012
Silver nanoparticles (AgNPs) have been the subjects of researchers due to their unique properties... more Silver nanoparticles (AgNPs) have been the subjects of researchers due to their unique properties such as size and shape, optical, antimicrobial and electrical properties. The emergence of nanotechnology and the production of nanomedicinal values from different sources had proven to be of great value in the field of biomedicine. Nanotechnology is a very important field of modern research dealing with the design, synthesis and manipulation of particle structures ranging from 1-100 nm [1]. In a chemical reduction process, silver nanoparticles are obtained along with toxic residuals which are undesirable for any sort of biomedical application. As a result, alternative methods are sought for the synthesis of silver nanoparticles without any known toxic by-products. Silver nanoparticles have also been synthesized from bacteria [2], fungus [3] and plants [4,5]. Synthesis of silver nanoparticles has been extensively studied using chemical and physical methods, but the development of reliable technology to produce nanoparticles is an important aspect of nanotechnology [6]. The biological methods have been suggested as eco-friendly alternatives to chemical methods [7]. The plants Characterization and Biological Activities of Silver Nanoparticles Synthesized from Stems of Sarcocephalus latifolius (Sm) E.A. Bruce and Massularia acuminata (G. Don) Bullock ex Hoyl. (Rubiaceae)
Conservar Património, 2016
Color Research & Application, 2015
Applied spectroscopy, 2016
The study and preservation of museum collections requires complete knowledge and understanding of... more The study and preservation of museum collections requires complete knowledge and understanding of constituent materials that can be natural, synthetic, or semi-synthetic polymers. In former times, objects were incorporated in museum collections and classified solely by their appearance. New studies, prompted by severe degradation processes or conservation-restoration actions, help shed light on the materiality of objects that can contradict the original information or assumptions. The selected case study presented here is of a box dating from the beginning of the 20th century that belongs to the Portuguese National Ancient Art Museum. Museum curators classified it as a tortoiseshell box decorated with gold applications solely on the basis of visual inspection and the information provided by the donor. This box has visible signs of degradation with white veils, initially assumed to be the result of biological degradation of a proteinaceous matrix. This paper presents the methodologic...
Applied Surface Science, 2016
Adherent deposits are very aggressive towards ancient heritage paintings since they affect the va... more Adherent deposits are very aggressive towards ancient heritage paintings since they affect the varnish and the painting&#39;s layers, sometimes reaching the preparative layers. The biggest problem to the restorer is their removal without affecting the patina, the transparent varnish (well preserved) and fine colour glazes made during painting. Therefore, their removal requires preliminary cleaning tests that allow the optimization of the cleaning system composition that is going to be used. The study was focused on organic natural systems, as colourless supernatants, some of them used during ages, but insufficiently studied. The paper presents an evaluation of the effectiveness of cleaning varnished icons of the nineteenth century, with complex conservation cases using supernatants derived from aqueous dispersions extracted from vegetables and dry indigenous herbal infusions. Best results, after six consecutive cleaning steps, on tempera old icon was obtained for a mixture made of mature white onion juice + extract of Soapwort flowers + corn silk tea + acacia tea. As a best result after just one cleaning step was obtained for a quaternary mixture composed from mature white onion juice + mature carrot juice + corn silk tea + aqueous extract of Soapwort flowers.
e-conservation Journal, 2014
ECMS 2015 Proceedings edited by: Valeri M. Mladenov, Petia Georgieva, Grisha Spasov, Galidiya Petrova, 2015
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Papers by Ana Teresa Caldeira