Search results for "biopolymers"
showing 10 items of 76 documents
Performance of polyester-based electrospun scaffolds under in vitro hydrolytic conditions: From short-term to long-term applications
2019
The evaluation of the performance of polyesters under in vitro physiologic conditions is essential to design scaffolds with an adequate lifespan for a given application. In this line, the degradation-durability patterns of poly(lactide-co-glycolide) (PLGA), polydioxanone (PDO), polycaprolactone (PCL) and polyhydroxybutyrate (PHB) scaffolds were monitored and compared giving, as a result, a basis for the specific design of scaffolds from short-term to long-term applications. For this purpose, they were immersed in ultra-pure water and phosphate buffer solution (PBS) at 37 °
Biostable Scaffolds of Polyacrylate Polymers Implanted in the Articular Cartilage Induce Hyaline-Like Cartilage Regeneration in Rabbits
2017
[EN] Purpose: To study the influence of scaffold properties on the organization of ¿in vivo¿ cartilage regeneration. Our hypothesis is that stress transmission to the cells seeded inside the scaffold pores or surrounding it, which is highly dependent on the scaffold properties, determine differentiation of both mesenchymal cells and dedifferentiated autologous chondrocytes. Methods: Four series of porous scaffolds made of different polyacrylate polymers, previously seeded with cultured rabbit chondrocytes or without cells preseeded, were implanted in cartilage defects in rabbits. Subchondral bone was always injured during the surgery in order to allow blood to reach the implantation site an…
Engineered Membranes for Residual Cell Trapping on Microfluidic Blood Plasma Separation Systems: A Comparison between Porous and Nanofibrous Membranes
2021
Blood-based clinical diagnostics require challenging limit-of-detection for low abundance, circulating molecules in plasma. Micro-scale blood plasma separation (BPS) has achieved remarkable results in terms of plasma yield or purity, but rarely achieving both at the same time. Here, we proposed the first use of electrospun polylactic-acid (PLA) membranes as filters to remove residual cell population from continuous hydrodynamic-BPS devices. The membranes hydrophilicity was improved by adopting a wet chemistry approach via surface aminolysis as demonstrated through Fourier Transform Infrared Spectroscopy and Water Contact Angle analysis. The usability of PLA-membranes was assessed through de…
Heat-Resistant Fully Bio-Based Nanocomposite Blends Based on Poly(lactic acid)
2013
Poly(lactic acid) (PLA) is melt mixed with polyamide 11 (PA11) to obtain a heat-resistant fully bio-based blend with PLA as the dominant component. The goal is achieved by adding small amounts of organoclay (OMMT), which is used to manipulate the blend microstructure. The selective positioning of the OMMT inside the PA11 and at the PLA/PA11 interface turns the blend morphology from drop/matrix into co-continuous at high PLA content (70 wt%). The OMMT-rich PA11 framework that interpenetrates the major PLA phase effectively contributes to bear stresses, and the nanocomposite blend keeps its structural integrity up to ≈160 °C, i.e., about 100 °C above the PLA glass transition.
Synthesis and Biological Evaluation of 1-Methyl-2-(3',4',5'-trimethoxybenzoyl)-3-aminoindoles as a New Class of Antimitotic Agents and Tubulin Inhibi…
2008
The 2-(3,4,5-trimethoxybenzoyl)-2-aminoindole nucleus was used as the fundamental structure for the synthesis of compounds modified with respect to positions C-4 to C-7 with different moieties (chloro, methyl, or methoxy). Additional structural variations concerned the indole nitrogen, which was alkylated with small alkyl groups such as methyl or ethyl. We have identified 1-methyl-2-(3,4,5-trimethoxybenzoyl)-3-amino-7-methoxyindole as a new highly potent antiproliferative agent that targets tubulin at the colchicine binding site and leads to apoptotic cell death.
Biodegradable nano-polymers as delivery vehicles for therapeutic small non-coding ribonucleic acids.
2016
Nowadays, small non-coding Ribo Nucleic Acids (sncRNAs) such as siRNA, miRNA and shRNA are extremely serving to gene regulation. They are involved in many biological processes and in an increasing number of studies regarding a variety of application of sncRNAs toward human health and relieving diseases ranging from metabolic disorders to those involving various organ systems as well as different types of cancer. One of the most severe limitations for applying RNA interference technology is the absence of safe and effective carriers for in vivo delivery, including localizing the molecules to a specific site of interest and sustaining the presentation of the payloads for a controlled period o…
Rev protein suppression of complex formation between nuclear proteins and rev-responsive element-containing RNA of human immunodeficiency virus-1
1995
The Rev protein from human immunodeficiency virus type 1 (HIV-1) is known to bind Rev responsive element (RRE) sequence of HIV-1 mRNA. This interaction is thought to enhance expression of viral structural proteins but the mechanism for this effect is uncertain. The aim of this study was to investigate (i) whether other cellular proteins also bind to the RRE sequence and (ii) whether binding of cellular proteins to RRE RNA is influenced by Rev protein. Our results revealed that a variety of RNA-protein complexes are formed when in vitro transcribed RRE-containing RNA is incubated with proteins present in HeLa nuclear extracts. The molecular masses of the most prominent bands in RNase protect…
Active packaging films with natural antioxidants to be used in meat industry: A review.
2018
Spoilage of meat products during processing, distribution and exposure in the markets have an important negative impact on meat industry from an economic point of view. Two of the main problems of meat and products during processing and subsequent storage are lipid oxidation and deterioration due to microorganism growth. In this context, several packaging alternatives have been developed by meat industry in order to limit these losses and to extend the meat products´ shelf life. Over the last years, the use of active packaging has been proposed as an alternative to traditional packaging. The principle of active packaging, particularly antioxidant active packaging, consists of including acti…
Nucleation and accretion of bioelastomeric fibers at biological temperatures and low concentrations.
1988
Quasi-elastic light scattering (QELS) studies are reported, which address the early stages of aggregation of the polypentamer poly(VPGVG). This reflects the major primary structural feature of native elastin. The study is focused on the region of the phase diagram which in both its temperature and concentration range is closest to the state of affairs occurring in the course of bioelastogenesis by progressive synthesis of the precursor protein. Results here reported allow for the first time a self-consistent view of the physics of elastogenesis, and specify the role of the region of metastability and of that of instability of the phase diagram in the non-chaotic, orderly formation of elasto…
Mesoscopic gels at low agarose concentration: perturbation effects of ethanol
1997
Aqueous agarose solutions at low concentrations (0.5 g/liter) were temperature quenched below the spinodal line to form mutually disconnected mesoscopic gels. In the presence of 6% ethanol, these solutions, obtained by quenching at the same temperature depth as in pure water, appear much more fluid, as determined by probe diffusion experiments. We show by static and dynamic light scattering that this can be explained by the solvent-mediated effects of ethanol, leading to a globular shape of mesoscopic agarose gels, rather than to an extended rodlike structure observed in pure water. Our findings show the significant effects of solvent perturbations on particle condensation and, therefore, m…