17 research outputs found
Probing single biomolecules with atomic force microscopy
Fritz J, Anselmetti D, Jarchow J, Fernandez-Busquets X. Probing single biomolecules with atomic force microscopy. Journal of structural biology. 1997;119(2):165-171.During the last years, atomic force microscopy (AFM) has developed from a microscopy tool for solid state surface science towards a method employed in many scientific disciplines such as biology to investigate individual molecules on a nanometer scale. This article describes the current status of the imaging possibilities of AFM on RNA, IgG and gold-labelled cell adhesion molecules, as well as of measurements of intermolecular binding forces between biomolecules in order to investigate their molecular structure, function and elasticity
Single molecule DNA biophysics with atomic force microscopy
Anselmetti D, Fritz J, Smith B, Fernandez-Busquets X. Single molecule DNA biophysics with atomic force microscopy. Single molecules. 2000;1(1):53-58.Structural and functional properties of double stranded deoxyribonucleic acid (dsDNA) are investigated by atomic force microscopy (AFM) on a single molecule level. Here, we characterize different linear and circular DNA systems in terms of their geometry and topology, and visualize enzyme binding of restriction endonuclease Hae III to DNA. Manipulation of single DNA molecules is demonstrated by dissecting individual DNA strands. Furthermore, the elastic response of single DNA molecules to an externally applied force is investigated by AFM force spectroscopy experiments. This gives information about structural properties of the DNA double helix. Specifically, transition from B-form to S-form DNA and a melting transition from double stranded to single stranded DNA is observed. This allows monitoring of specific interaction and binding of small intercalator molecules such as ethidium bromide (EtBr) to DNA by means of a mechanical, non-fluorescent detection scheme
Proteoglycan mechanics studied by single-molecule force spectroscopy of allotypic cell adhesion glycans
Author Posting. © American Society for Biochemistry and Molecular Biology, 2006. This article is posted here by permission of American Society for Biochemistry and Molecular Biology for personal use, not for redistribution. The definitive version was published in Journal of Biological Chemistry 281 (2006): 5992-5999, doi:10.1074/jbc.M507878200.Early Metazoans had to evolve the first cell adhesion system addressed to maintaining stable interactions between cells constituting different individuals. As the oldest extant multicellular animals, sponges are good candidates to have remnants of the molecules responsible for that crucial innovation. Sponge cells associate in a species-specific process through multivalent calcium-dependent interactions of carbohydrate structures on an extracellular membrane-bound proteoglycan termed aggregation factor. Single-molecule force spectroscopy studies of the mechanics of aggregation factor self-binding indicate the existence of intermolecular carbohydrate adhesion domains. A 200-kDa aggregation factor glycan (g200) involved in cell adhesion exhibits interindividual differences in size and epitope content which suggest the existence of allelic variants. We have purified two of these g200 distinct forms from two individuals of the same sponge species. Comparison of allotypic versus isotypic g200 binding forces reveals significant differences. Surface plasmon resonance measurements show that g200 self-adhesion is much stronger than its binding to other unrelated glycans such as chondroitin sulfate. This adhesive specificity through multiple carbohydrate binding domains is a type of cooperative interaction that can contribute to explain some functions of modular proteoglycans in general. From our results it can be deduced that the binding strength/surface area between two aggregation factor molecules is comparable with that of focal contacts in vertebrate cells, indicating that strong carbohydrate-based cell adhesions evolved at the very start of Metazoan history.This work was supported in part by Grants BIO2002-00128 and BIO2005-01591 (both to
X. F.-B.) from the Ministerio de EducacioÂŽn y Ciencia, Spain, which included Fondo
Europeo de Desarrollo Regional funds
Liposomal Formulations to Improve Antioxidant Power of Myrtle Berry Extract for Potential Skin Application
Many substances in plant extracts are known for their biological activities. These substances act in different ways, exerting overall protective effects against many diseases, especially skin disorders. However, plant extractsâ health benefits are often limited by low bioavailability. To overcome these limitations, drug delivery systems can be employed. In this study, we evaluated the antioxidant power of an ethanolic extract from Myrtus communis L. (myrtle) berries through colorimetric tests (DPPH and FRAP). The antioxidant activity was also verified by using fibroblast cell culture through cellular Reactive Oxygen Species (ROS) levels measurements. Moreover, the myrtle extract was formulated in phospholipid vesicles to improve its bioavailability and applicability. Myrtle liposomes were characterized by size, surface charge, storage stability, and entrapment efficiency; visualized by using cryo-TEM images; and assayed for cytocompatibility and anti-ROS activity. Our results suggest that myrtle liposomes were cytocompatible and improved the extractâs antioxidant power in fibroblasts, suggesting a potential skin application for these formulations and confirming that nanotechnologies could be a valid tool to enhance plant extractsâ potentialities
Electrochemical POC device for fast malaria quantitative diagnosis in whole blood by using magnetic beads, Poly-HRP and microfluidic paper electrodes
© 2019 Elsevier B.V. Malaria, a parasitic infection caused by Plasmodium parasites and transmitted through the bite of infected female Anopheles mosquitos, is one of the main causes of mortality in many developing countries. Over 200 million new infections and nearly half a million deaths are reported each year, and more than three billion people are at risk of acquiring malaria worldwide. Nevertheless, most malaria cases could be cured if detected early. Malaria eradication is a top priority of the World Health Organisation. However, achieving this goal will require mass population screening and treatment, which will be hard to accomplish with current diagnostic tools. We report an electrochemical point-of-care device for the fast, simple and quantitative detection of Plasmodium falciparum lactate dehydrogenase (PfLDH) in whole blood samples. Sample analysis includes 5-min lysis to release intracellular parasites, and stirring for 5 more min with immuno-modified magnetic beads (MB) along with an immuno-modified signal amplifier. The rest of the magneto-immunoassay, including sample filtration, MB washing and electrochemical detection, is performed at a disposable paper electrode microfluidic device. The sensor provides PfLDH quantitation down to 2.47 ng mLâ1 in spiked samples and for 0.006â1.5% parasitemias in Plasmodium-infected cultured red blood cells, and discrimination between healthy individuals and malaria patients presenting parasitemias >0.3%. Quantitative malaria diagnosis is attained with little user intervention, which is not achieved by other diagnostic methods
Extracellular Vesicles Derived from Plasmodium-infected and Non-infected Red Blood Cells as Targeted Drug Delivery Vehicles
Among several factors behind drug resistance evolution in
malaria is the challenge of administering overall doses that are not toxic for the patient but that, locally, are sufficiently
high to rapidly kill the parasites. Thus, a crucial antimalarial
strategy is the development of drug delivery systems capable of
targeting antimalarial compounds to Plasmodium with high
specificity. In the present study, extracellular vesicles (EVs)
have been evaluated as a drug delivery system for the treatment
of malaria. EVs derived from naive red blood cells (RBCs) and
from Plasmodium falciparum-infected RBCs (pRBCs) were isolated
by ultrafiltration followed by size exclusion chromatography.
Lipidomic characterization showed that there were no significant
qualitative differences between the lipidomic profiles of
pRBC-derived EVs (pRBC-EVs) and RBC-derived EVs (RBC-EVs). Both
EVs were taken up by RBCs and pRBCs, although pRBC-EVs were more
efficiently internalized than RBC-EVs, which suggested their
potential use as drug delivery vehicles for these cells. When
loaded into pRBC-EVs, the antimalarial drugs atovaquone and
tafenoquine inhibited in vitro P. falciparum growth more
efficiently than their free drug counterparts, indicating that
pRBC-EVs can potentially increase the efficacy of several small
hydrophobic drugs used for the treatment of malaria
Nanotherapeutics against malaria: A decade of advancements in experimental models
Malaria, caused by different species of protists of the genus Plasmodium, remains among the most common causes of death due to parasitic diseases worldwide, mainly for children aged under 5. One of the main obstacles to malaria eradication is the speed with which the pathogen evolves resistance to the drug schemes developed against it. For this reason, it remains urgent to find innovative therapeutic strategies offering sufficient specificity against the parasite to minimize resistance evolution and drug side effects. In this context, nanotechnology-based approaches are now being explored for their use as antimalarial drug delivery platforms due to the wide range of advantages and tuneable properties that they offer. However, major challenges remain to be addressed to provide a cost-efficient and targeted therapeutic strategy contributing to malaria eradication. The present work contains a systematic review of nanotechnology-based antimalarial drug delivery systems generated during the last 10 years. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Diseas
Exploring the Design of a Wearable Device to Turn Everyday Objects into Playful Experiences
In this paper we present a wearable device in the form of a bracelet that turns everyday objects into interactive physical gameplay. We combine physical exploration and interactive entertainment by providing real-time audio and light feedback without the need to be in front of a screen. In contrast with today's computer, video and smartphone games, our system has the potential to enhance children's physical, social and outdoor play. We designed a set of playful applications that seamlessly integrate technology with outdoor game play, music, sports and social interactions
Optical-Tweezers Study of Topoisomerase Inhibition
Pla D, Sischka A, Albericio F, Alvarez M, Fernandez-Busquets X, Anselmetti D. Optical-Tweezers Study of Topoisomerase Inhibition. Small. 2009;5(11):1269-1272
A single-molecule force spectroscopy nanosensor for the identification of new antibiotics and antimalarials
Sisquella X, de Pourcq K, Alguacil J, et al. A single-molecule force spectroscopy nanosensor for the identification of new antibiotics and antimalarials. FASEB JOURNAL. 2010;24(11):4203-4217