1,721,134 research outputs found
Aerogels Part 2. A Focus on the Less Patented and Marketed Airy Inorganic Networks Despite the Plethora of Possible Advanced Applications
No full textRecently, the state of the art of aerogels (AGs) has been reviewed, reporting first on their classification, based on the chemical origin of their precursors and the different methods existing to prepare them. Additionally, AGs of inorganic origin (IAGs) were contemplated, deeply discussing the properties, specific synthesis, and possible uses of silica and metal oxide-based AGs, since they are the most experimented and patented AGs already commercialized in several sectors. In this second part review, IAGs are examined again, but chalcogenide and metals AGs (CAGs and MAGs) are debated, since they are still too little studied, patented, and marketed, despite their nonpareil properties and vast range of possible applications. First, to give readers unaware of the previous work on AGs, a background about IAGs, all their main subclasses have been reported and their synthesis, including sol-gel, epoxide addition (EA), and dispersed inorganic (DIS) methods, as well as procedures involving the use of pre-synthesized nanoparticles as building blocks, have been discussed. Morphology and microstructure images of materials prepared by such synthetic method have been supplied. Conversely, the methods needed to prepare CAGs and MAGs, topics of this study, have been debated separately in the related sections, with illustrative SEM images. Their possible uses, properties, and some comparisons of their performance with that of other AGs and not AG materials traditionally tested for the same scopes, have also been disserted, reporting several case studies in reader-friendly tables
Assessment of the prediction efficiency of three simulation software concerning the conformity of compostable shoppers from a packaging industry before TÜV verification
No full textFTIR analysis is used in industry because fast, reliable, low cost. FTIR data are usually processed by Principal Component Analysis (PCA), worked up by commercial simulation software. For their simulation power, even if not included in CAE software, the prediction efficiency of JMP, MatLab and R was assessed in an eco-friendly study on the conformity of compostable shoppers (Mecplast). Despite some differences in separation efficiency, all software provided similar results, proving Mecplast items regularity and revealing an alarming presence on the market of certified but irregular shoppers
New promising vectors for gene delivery by a step-wise functionalization of a polyester-based non toxic dendrimer with N,N-dimethylglicine, N-methylglicine, lysine and arginine
No full textPolycationic dendrimers are able to electrostatically bind genetic material forming nanosized complexes (polyplexes). They result very appealing for applications as non-viral vectors to bring DNA or RNA within genetically defective cells for treating or solving several diseases including cancer. Commonly used cationic polymers (bPEI) or dendrimers (PAMAM), thanks to a good buffer capacity due to the several weakly basic amines in their structure, once in the cell, induce an osmotic swelling of endosomes that contain the polyplexes leading to content release (1). For this reason bPEI and PAMAM are endowed with high transfection efficiencies (2) but, if not chemically modified do not find real applications in gene therapy because of their cytotoxicity. It is also known that dendrimers containing arginine improve siRNA cellular uptake (3) and are equipped with higher efficiency of transfection and reduced toxicity (4, 5). In respect of this background in this communication we report the setting up of versatile protocols to introduce on the hydrolysable polyester-based fourth generation dendrimer (1) previously prepared, a mixture of N, N-dimethyl glycine, N-methylglicine, lysine, and arginine. The synergic presence of nitrogen atoms with different pKa and the arginine moiety should have promoted the cellular up-take and should have contributed to an optimal buffering capacity enhancing the endosomal escape and improving transfection activity.
The obtained products in the hydrochloride forms were subjected to volumetric titration to determine experimental molecular weight and to NMR analysis to confirm the structures. Potentiometric titration to calculate the buffer capacity (β) and then the average buffer capacity and the NMR characterization of all the intermediates were also performed.
References: 1. Behr, J. P. Chimia 1997, 51, 34-36. 2. Akinc, A.; Thomas, M.; Klibanov, A. M.; Langer, R. J Gene Med. 2005, 7, 657–663. 3. Liu, X.; Liu, C.; Zhou, J.; Chen, C.; Qu, F.; Rossi, J. J.; Rocchi, P.; Peng L. Nanoscale 2015, 7, 3867-3875. 4. Kim, T.; Bai, C. Z.; Nam, K.; Park, J. J. Control. Release 2009, 136, 132-139. 5. Peng, Q.; Zhu, J.; Yu, Y.; Hoffman, L.; Yang, X. J. Biomater. Sci. Polym. Ed. 2015, 26, 1163-1177
Shifting from Ammonium to Phosphonium Salts: A Promising Strategy to Develop Next-Generation Weapons against Biofilms
No full textSince they are difficult and sometimes impossible to treat, infections sustained by multidrug-resistant (MDR) pathogens, emerging especially in nosocomial environments, are an increasing global public health concern, translating into high mortality and healthcare costs. In addition to having acquired intrinsic abilities to resist available antibiotic treatments, MDR bacteria can transmit genetic material encoding for resistance to non-mutated bacteria, thus strongly decreasing the number of available effective antibiotics. Moreover, several pathogens develop resistance by forming biofilms (BFs), a safe and antibiotic-resistant home for microorganisms. BFs are made of well-organized bacterial communities, encased and protected in a self-produced extracellular polymeric matrix, which impedes antibiotics’ ability to reach bacteria, thus causing them to lose efficacy. By adhering to living or abiotic surfaces in healthcare settings, especially in intensive care units where immunocompromised older patients with several comorbidities are hospitalized BFs cause the onset of difficult-to-eradicate infections. In this context, recent studies have demonstrated that quaternary ammonium compounds (QACs), acting as membrane disruptors and initially with a low tendency to develop resistance, have demonstrated anti-BF potentialities. However, a paucity of innovation in this space has driven the emergence of QAC resistance. More recently, quaternary phosphonium salts (QPSs), including tri-phenyl alkyl phosphonium derivatives, achievable by easy one-step reactions and well known as intermediates of the Wittig reaction, have shown promising anti-BF effects in vitro. Here, after an overview of pathogen resistance, BFs, and QACs, we have reviewed the QPSs developed and assayed to this end, so far. Finally, the synthetic strategies used to prepare QPSs have also been provided and discussed to spur the synthesis of novel compounds of this class. We think that the extension of the knowledge about these materials by this review could be a successful approach to finding effective weapons for treating chronic infections and device-associated diseases sustained by BF-producing MDR bacteria
Cationic Materials for Gene Therapy: A Look Back to the Birth and Development of 2,2-Bis-(hydroxymethyl)Propanoic Acid-Based Dendrimer Scaffolds
No full textGene therapy is extensively studied as a realistic and promising therapeutic approach for treating inherited and acquired diseases by repairing defective genes through introducing (transfection) the “healthy” genetic material in the diseased cells. To succeed, the proper DNA or RNA fragments need efficient vectors, and viruses are endowed with excellent transfection efficiency and have been extensively exploited. Due to several drawbacks related to their use, nonviral cationic materials, including lipidic, polymeric, and dendrimer vectors capable of electrostatically interacting with anionic phosphate groups of genetic material, represent appealing alternative options to viral carriers. Particularly, dendrimers are highly branched, nanosized synthetic polymers characterized by a globular structure, low polydispersity index, presence of internal cavities, and a large number of peripheral functional groups exploitable to bind cationic moieties. Dendrimers are successful in several biomedical applications and are currently extensively studied for nonviral gene delivery. Among dendrimers, those derived by 2,2-bis(hydroxymethyl)propanoic acid (b-HMPA), having, unlike PAMAMs, a neutral polyester-based scaffold, could be particularly good-looking due to their degradability in vivo. Here, an overview of gene therapy, its objectives and challenges, and the main cationic materials studied for transporting and delivering genetic materials have been reported. Subsequently, due to their high potential for application in vivo, we have focused on the biodegradable dendrimer scaffolds, telling the history of the birth and development of b-HMPA-derived dendrimers. Finally, thanks to a personal experience in the synthesis of b-HMPA-based dendrimers, our contribution to this field has been described. In particular, we have enriched this work by reporting about the b-HMPA-based derivatives peripherally functionalized with amino acids prepared by us in recent years, thus rendering this paper original and different from the existing reviews
Aerogels Part 1: A Focus on the Most Patented Ultralight, Highly Porous Inorganic Networks and the Plethora of Their Advanced Applications
No full textAerogels (AGs) are highly porous, low-density, disordered, ultralight macroscopic materials with immense surface areas. Traditionally synthesized using aqueous sol–gel chemistry, starting by molecular precursors, the nanoparticles (NPs) dispersions gelation method is nowadays the most used procedure to obtain AGs with improved crystallinity and broader structural, morphological and compositional complexity. The Sol–gel process consists of preparing a solution by hydrolysis of different precursors, followed by gelation, ageing and a drying phase, via supercritical, freeze-drying or ambient evaporation. AGs can be classified based on various factors, such as appearance, synthetic methods, chemical origin, drying methods, microstructure, etc. Due to their nonpareil characteristics, AGs are completely different from common NPs, thus covering different and more extensive applications. AGs can be applied in supercapacitors, acoustic devices, drug delivery, thermal insulation, catalysis, electrocatalysis, gas absorption, gas separation, organic and inorganic xenobiotics removal from water and air and radionucleotides management. This review provides first an analysis on AGs according to data found in CAS Content Collection. Then, an AGs’ classification based on the chemical origin of their precursors, as well as the different methods existing to prepare AGs and the current optimization strategies are discussed. Following, focusing on AGs of inorganic origin, silica and metal oxide-based AGs are reviewed, deeply discussing their properties, specific synthesis and possible uses. These classes were chosen based on the evidence that they are the most experimented, patented and marketed AGs. Several related case studies are reported, some of which have been presented in reader-friendly tables and discussed
Preparation and characterization of water-soluble, not PAMAM-structured dendrimer prodrugs of an anti-HIV-1 O-TC derivative for in vivo and clinical applications.
No full textSynthesis of arginine-decorated amphipilic dendrimers
No full textDendrimers are macromolecules characterized by well defined molecular structures, narrow polydispersity index, generally high solubility and stability. Cationic dendrimers for their capacity of electrostatically binding genetic materials to form nanosized complexes find applications as non-viral vectors to deliver the genetic material into target cells in order to correct genetic defects (gene therapy). Since polycation systems are often toxic and show moderate transfection ability, chemical modifications aimed at introducing molecular moieties able to reduce these drawbacks are required. In this respect the arginine moiety appears particularly appealing since it is known that dendrimers containing arginine are known to improve siRNA cellular uptake1 and efficiency of transfection.2 The presence of hydrophobic segments in the dendrimer structure is also important in the internalization process.3
In this communication we report synthesis and NMR characterization of new polycation polyester-based dendrimers modified both at the core with a C-18 saturated alkyl chain and at the periphery by introducing arginine or arginine and lysine residues.
The presented multistep syntheses exploit 2-hydroxymethyl-2-methyl-1,3-propanediol as the core molecule and 2,2-bis(hydroxymethyl)propanoic acid as the building block to create the polyester backbone.
1) LIU, X.; LIU, C.; ZHOU, J.; CHEN, C.; QU, F.; ROSSI, J. J.; ROCCHI, P.; PENG L. Nanoscale 2015, 7, 3867-3875.
2) KIM, T.; BAI, C. Z.; NAM, K.; PARK, J. J. Control. Release 2009, 136, 132-139.
3) WANG, F.; WANG, Y.; WANG, H.; SHAO, N.; CHEN, Y.; CHENG, Y. Biomaterials 2014, 35, 9187-9198
Oxidative Stress, Antioxidant Capabilities, and Bioavailability: Ellagic Acid or Urolithins?
No full textOxidative stress (OS), triggered by overproduction of reactive oxygen and nitrogen
species, is the main mechanism responsible for several human diseases. The available one-target
drugs often face such illnesses, by softening symptoms without eradicating the cause. Differently,
natural polyphenols from fruits and vegetables possess multi-target abilities for counteracting OS,
thus representing promising therapeutic alternatives and adjuvants. Although in several in vitro
experiments, ellagitannins (ETs), ellagic acid (EA), and its metabolites urolithins (UROs) have
shown similar great potential for the treatment of OS-mediated human diseases, only UROs have
demonstrated in vivo the ability to reach tissues to a greater extent, thus appearing as the main
molecules responsible for beneficial activities. Unfortunately, UROs production depends on individual
metabotypes, and the consequent extreme variability limits their potentiality as novel therapeutics, as
well as dietary assumption of EA, EA-enriched functional foods, and food supplements. This review
focuses on the pathophysiology of OS; on EA and UROs chemical features and on the mechanisms of
their antioxidant activity. A discussion on the clinical applicability of the debated UROs in place of
EA and on the effectiveness of EA-enriched products is also includedOxidative stress (OS), triggered by overproduction of reactive oxygen and nitrogen species, is the main mechanism responsible for several human diseases. The available one‐target drugs often face such illnesses, by softening symptoms without eradicating the cause. Differently, natural polyphenols from fruits and vegetables possess multi‐target abilities for counteracting OS, thus representing promising therapeutic alternatives and adjuvants. Although in several in vitro experiments, ellagitannins (ETs), ellagic acid (EA), and its metabolites urolithins (UROs) have shown similar great potential for the treatment of OS‐mediated human diseases, only UROs have demonstrated in vivo the ability to reach tissues to a greater extent, thus appearing as the main molecules responsible for beneficial activities. Unfortunately, UROs production depends on individual metabotypes, and the consequent extreme variability limits their potentiality as novel therapeutics, as well as dietary assumption of EA, EA‐enriched functional foods, and food supplements. This review focuses on the pathophysiology of OS; on EA and UROs chemical features and on the mechanisms of their antioxidant activity. A discussion on the clinical applicability of the debated UROs in place of EA and on the effectiveness of EA‐enriched products is also included
Tert-Butoxycarbonyl Protecting Group Location Induces Different Reactive Behaviors in the Five Possible Isoforms of Tri-Boc-Arginine
No full textL-arginine is often used to decorate several scaffolds in order to obtain biomedical devices with increased efficiency and reduced toxicity, so nitrogen atoms need protection for example with BOC group. It has recently been reported that following three protocols which assured the achievement of the widely described (E)-αN,ωN,ω’N-Tri-BOC-arginine as pure isoform, additional four isoforms were obtained. As a rational consequence, further investigations about their reactivity were performed and in this work the results that showed as it is influenced by BOC location, isoforms structure and double bond position and geometry were reported. Only one isoform, i. e. rotamer E, shown appreciable reactivity highlighting that only the procedure which provides it is actually valid. From rotamer E, two new first generation arginine dendrons were prepared. These fragments, exploitable for decorating dendrimer, polymer or lipid scaffolds are very appealing for preparing synthetic arginine materials potentially suitable for biomedical application. Their spectral characterization as well as that of three other unreported isolated compounds were also provide
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