1,720,993 research outputs found
Studying the colloidal behavior of chimeric liposomes by cryo-TEM, micro-differential scanning calorimetry and high-resolution ultrasound spectroscopy
No full textThe investigation of colloidal properties of nanosystems represents a fundamental issue for the development of nanotechnology-based medicines. The aim of this study is to combine various techniques in order to characterize more comprehensively chimeric nanovesicles composed of block or gradient block copolymers with different architectures and compositions. Several chimeric systems were prepared and the impact of the block [poly(ε-caprolactone)−poly(ethylene oxide); PEO-b-PCL] and gradient block [poly(2-methyl-2-oxazoline)-grad-poly(2-phenyl-2-oxazoline); MPOx] copolymers on the physicochemical and morphological characteristics of conventional 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes was examined. Light scattering techniques and cryo-TEM were used for the physicochemical and morphological characterization of the prepared systems. The size and the morphology were strongly related to the architecture and the composition of the polymeric compounds. Micro differential scanning calorimetry and high-resolution ultrasound spectroscopy were used for investigating the interactions between the DPPC lipids and the polymeric guest. An increase in the main transition temperature was observed for the prepared chimeric systems in comparison to DPPC liposomes. In conclusion, a detailed characterization of the colloidal behavior of chimeric liposomes can benefit from the combination of the aforementioned techniques that operate synergistically, giving information on their physicochemical and morphological characteristics as well as on their thermotropic behavior
Incorporation of PEGylated δ-decalactone into lipid bilayers: thermodynamic study and chimeric liposomes development
No full textLiposomes have been on the market as drug delivery systems for over 25 years. Their success comes from the ability to carry toxic drug molecules to the appropriate site of action through passive accumulation, thus reducing their severe side effects. However, the need for enhanced circulation time and site and time specific drug delivery, turned research focus on other systems, such as polymers. In this context, novel composites that combine the flexibility of polymeric nanosystems with the properties of liposomes gained a lot of interest. In the present work a mixed/chimeric liposomal system, composed of phospholipids and block copolymers, was developed and evaluated in regards with its feasibility as a drug delivery system. These innovative nano-platforms combine advantages from both classes of biomaterials. Thermal analysis was performed in order to offers an insight into the interactions between these materials and consequently into their physicochemical characteristics. In addition, colloidal stability was assessed by monitoring z-potential and size distribution over time. Finally, their suitability as carriers for biomedical applications was evaluated by carrying out in vitro toxicity studies
PEO-b-PCL/Tween 80/cyclodextrin systems: from bioinspired fabrication to possible nasal administration of ropinirole hydrochloride
No full textIn this study, we designed and developed systems composed of poly(ethylene-oxide)-b-poly(ε-caprolactone) block copolymers of different molecular weights and compositions, non-ionic surfactant, and cyclodextrins. The innovation of this study lies in the combination of these diverse biomaterials to create biomimetic and bioinspired drug delivery supramolecular structures. The systems were formed by the thin-film hydration method. Extensive physicochemical and morphological characterization was conducted using differential scanning calorimetry, light scattering techniques, microcalorimetry analysis, high-resolution ultrasound spectroscopy, surface tension measurements, fluorescence spectroscopy, cryogenic transmission electron microscopy images, and in vitro cytotoxicity evaluation. These innovative hybrid nanoparticles were found to be attractive candidates as drug delivery systems with unique properties by encompassing the physicochemical and thermotropic properties of both classes of materials. Subsequently, Ropinirole hydrochloride was used as a model drug for the purpose of this study. These systems showed a high RH content (%), and in vitro diffusion experiments revealed that more than 90% of the loading dose was released under pH and temperature conditions that simulate the conditions of the nasal cavity. Promising drug release performance was observed with all tested formulations, worth further investigation to explore both ex vivo permeation through the nasal mucosa and in vivo performance in an experimental animal model
Additive manufacturing methods for pharmaceutical and medical applications
No full textThree-dimensional (3D) printing has been geared up to become a highly revolutionary technology within the manufacturing industry, especially within the pharmaceutical and medical fields. Three-dimensional printing utilizes computer-aided design (CAD) software to manufacture objects of any size and shape. Due to the potential capabilities, many industries are now making use of this manufacturing technique, from rapid prototyping in engineering to the production of personalized medicine within the medical and pharmaceutical industries. It has the potential to cause a paradigm shift and revolutionize the way medicines and medical devices are designed, manufactured, and used. This chapter provides an overview of the field of 3D printing, current medical applications, 3D-printed dosage forms, and drug delivery systems as well as the benefits and limitations of this technique. It focuses on the potential and motivations of this method of additive manufacturing, including the challenges and future possibilities it could bring to the field of medicine and pharmaceuticals.<br/
Deciphering the Lipid-Random Copolymer Interactions and Encoding Their Properties to Design a Hybrid System
No full textLipid/copolymer colloidal systems are deemed hybrid materials with unique properties and functionalities. Their hybrid nature leads to complex interfacial phenomena, which have not been fully encoded yet, navigating their properties. Moving toward in-depth knowledge of such systems, a comprehensive investigation of them is imperative. In the present study, hybrid lipid/copolymer structures were fabricated and examined by a gamut of techniques, including dynamic light scattering, fluorescence spectroscopy, cryogenic transmission electron microscopy, microcalorimetry, and high-resolution ultrasound spectroscopy. The biomaterials that were mixed for this purpose at different ratios were 1,2-dioctadecanoyl-sn-glycero-3-phosphocholine and four different linear, statistical (random) amphiphilic copolymers, consisting of oligo(ethylene glycol) methyl ether methacrylate as the hydrophilic comonomer and lauryl methacrylate as the hydrophobic one. The colloidal dispersions were studied for lipid/copolymer interactions regarding their physicochemical, morphological, and biophysical behavior. Their membrane properties and interactions with serum proteins were also studied. The aforementioned techniques confirmed the hybrid nature of the systems and the location of the copolymer in the structure. More importantly, the random architecture of the copolymers, the hydrophobic-to-hydrophilic balance of the nanoplatforms, and the lipid-to-polymer ratio are highlighted as the main design-influencing factors. Elucidating the lipid/copolymer interactions would contribute to the translation of hybrid nanoparticle performance and, thus, their rational design for multiple applications, including drug delivery
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Thermodynamics and biophysics of biomedical nanosystems: applications and practical considerations
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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