200 research outputs found
Silver nanoparticle impregnated polycarbonate substrates for plasmonic applications
No full textWe present a new class of plasmonic substrates where silver nanoparticles are impregnated into a polycarbonate host. The substrates are shown to be exceptional candidates for SERS and metal enhanced fluorescence applications
Novel Insulating Material from Renewable Resouerces : Silicate-Lignin Foam Composite
No full textSilicate-Lignin Foam Composites as eco-friendly insulating materials
Silvia Bordoni, Inorganic and Physical Chemistry Dept, University of Bologna
Laura Genovese, ICIE Architecture Lab for technology transfer in Constructions, Bologna
Organic-inorganic composite materials have been extensively studied for a long time, since they combine advantages of the inorganic material (i.e. rigidity, thermal stability) and of the organic phase, which is, in most of cases, a polymer (i.e. flexibility, ductility and processability (1).
Among several organic/inorganic hybrid materials, the polymer/silica nano- and meso-composites are the most commonly reported in literature and have attracted both academic and industrial interests. Besides the common applications, including coating, catalysts, devices and sensors, this type of composites can be also employed to realize innovative construction materials (2).
Here we report a formulation from renewable sources of a novel thermal- insulating material, able to offer an eco-friendly alternative to the conventional light-weighed synthetic products. The designed material is an organic-inorganic composite of lignosulfonate, as the main waste product of cellulose-production, dispersed into a silicate matrix with the addition of non-food corn starch, acting as gluing agent. The further addition of esterification promoters, foaming and coupling agents, polyol acids as pH-regulators, fungi preservatives and Kenaf fibers as reinforcing agents, confers the tailored targeted features. Addition of a suitable coupling agent (APTES) promotes linkage between the polyol groups of glycerol or the surfactant lignosulfonate with silanol and siloxane moieties of the silicate substrate. The resulting blended biopolymers-microporous silica material (40m) appears as a single phase rigid foam, which conjugates low-density (0.25-0.35g/cm3), low conductivity (λ= 52-61mW/m2K) and acceptable mechanical properties (3). These features make the obtained composite useful for bored-brick filler or as small insulating panels in building applications. Recent efforts to enhance hydrophobicity to reduce biodegradability by starch acetylation and to introduce benign polycarboxylic acids as alternative expanding promoters, more efficient plasticizers (sorbitol) or foam stabilizers and rheology modifiers (xanthane), will be also presented.
1. H.Zou, S. Wu, J.Shen; Chem. Rev. 2008, 108, 3893-3957
2. Common Strategic Framework for Research and Innovation ,“Horizon 2020”.
3. S. Bordoni; An eco-friendly challenge; Festival della scienza, Genova, 201
Surface Characterisation of Bioadhesive PLGA/Chitosan Microparticles Produced by Supercritical Fluid Technology
No full textPurpose: Novel biodegradable and mucoadhesive PLGA/chitosan microparticles with the potential for use as a controlled release gastroretentive system were manufactured using supercritical CO 2 (scCO 2) by the Particle Gas Saturated System (PGSS) technique (also called CriticalMix TM). Methods: Microparticles were produced from PLGA with the addition of mPEG and chitosan in the absence of organic solvents, surfactants and crosslinkers using the PGSS technique. Microparticle formulations were morphologically characterized by scanning electron microscope; particle size distribution was measured using laser diffraction. Microparticle surface was analyzed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to evaluate the presence of chitosan on the surface. Mucoadhesiveness of the microparticles was evaluated in vitro using a mucin assay employing two different kinds of mucin (Mucin type III and I-S) with different degrees of sialic acid contents, 0.5-1.5% and 9-17%, respectively. Results: The two analytical surface techniques (XPS and ToF-SIMS) demonstrated the presence of the chitosan on the surface of the particles (<100 μm), dependent on the polymer composition of the microparticles. The interaction between the mucin solutions and the PLGA/chitosan microparticles increased significantly with an increasing concentration of mucin and chitosan. Conclusions: The strong interaction of mucin with the chitosan present on the surface of the particles suggests a potential use of the mucoadhesive carriers for gastroretentive and oral controlled drug release
Development Of Smart Polydiacetylene Micelles For In Vitro And In Vivo Tracking
No full textPolydiacetylenes (PDAs) are conjugated polymers that can form highly ordered structures with unique chromatic features. PDAs are typically obtained by polymerisation of diacetylene (DA) monomers using ultraviolet (UV) light irradiation without the need of any initiators, which generates a polymeric backbone with alternating C=C and C≡C bonds (one-yne), giving a blue non-fluorescent PDAs. Several stimuli, such as pH, temperature and ligand-receptor interaction, can induce a red-shift and weakly fluorescent colorimetric transition that makes PDAs a very interesting system in the field of sensors and drug delivery systems [1,2].
PDAs systems are usually prepared using amphiphilic commercial monomers like 10,12 - pentacosadyinoic acid (PCDA) and 10,12 - tricosadyinoic acid (TCDA), with the addition in the final formulation of phospholipids [3] and/or water-soluble polymers [4], that can influence PDAs system sensitivity, stability and drug-released properties.
In the present project, we selected poly(glycerol adipate) (PGA) as a novel greener polymeric alternative to develop PDAs mixed-micelles. The addition of PGA will confer to the final formulations biodegradability and biocompatibility [5]. Furthermore, PGA can self-assembly into nanoparticles (NPs) in aqueous media using nanoprecipitation method, which is highly compatible with traditional process for the formation of PDAs [6]. Due to PGA low toxicity and possibility to produce active polymeric prodrugs by drug coupling to the PGA backbone, PDA/PGA mixed-micelles can be considered a potential platform intrinsically biodegradable which may facilitate in vivo and in vitro tracking of delivery systems [7].
[1] X. Qian and B. Stadler, Chem. Mater. 2019, 31(4), 1196-1222.
[2] F. Fang, F. Meng, L. Luo, Mater. Chem. Front. 2020, 4(4), 1089,1104
[3] G.P. Camilloto, C.G. Otoni, G.W.R. de Almeida, I.R.N de Oliveira, L.H.M. da Silva, A.C. dos Santos Pires, N. De F.F. Soares. ACS Food Sci. Technol. 2021, 1(5), 745-753.
[4] A. Pankaew, N. Traiphol, R. Traiphol, Colloids Surf. Physicochem. Eng. Asp. 2021, 608, 125626.
[5] P.L. JacobsL.A. Ruiz Cantu, A.K. Pearce, Y. He, J.C. Lentz, J.C. Moore, F.Machado, G.Rivers, E. Apebende, M.R. Fernandenz, I. Francolini, R. Wildman, S.M. Howdle, V. Taresco, Poly (Glycerol Adipate) (PGA) Backbone Modifications with a Library of Functional Diols: Chemical and Physical Effects. Polymer, 228, 123912
[6] P. Kallinteri, S. Higgins, G.A. Hutcheon, C.B. St Pourcain, M.C. Garnett. Biomacromolecules
The scale-up of a tissue engineered porous hydroxyapatite polymer composite scaffold for use in bone repair: an ovine femoral condyle defect study
No full textThe development of an osteogenic bone graft substitute has important practical and cost implications in many branches of medicine where bone regeneration is required. Previous in vitro and small animal (murine) in vivo studies highlighted a porous hydroxyapatite/poly (dl‐lactic acid) composite scaffold in combination with skeletal stem cells (SSCs) as a potential bone graft substitute candidate. The aim of the current study was to scale up the bone cell‐scaffold construct to large animals and examine the potential for repair of a critical‐sized defect via an ovine model. SSC seeded scaffolds (and unseeded scaffold controls) were implanted bilaterally into ovine femoral condyle critical defects for 3 months. A parallel in vitro analysis of ovine SSC seeded scaffolds was also performed. Post mortem mechanical indentation testing showed the bone strengths of the defect sites were 20% (controls) and 11% (SSC seeded scaffolds) those of normal cancellous bone (p < 0.01). MicroCT analysis demonstrated new bone formation within all defects with a mean increase of 13.4% in the control scaffolds over the SSC seeded scaffolds (p = 0.14). Histological examination confirmed these findings, with enhanced quality new bone within the control defects. This study highlights important issues and steps to overcome in scale‐up and translation of tissue engineered products. The scaffold demonstrated encouraging results as an osteoconductive matrix; however, further work is required with cellular protocols before any human trials
PEGylated chitosan derivatives: Synthesis, characterizations and pharmaceutical applications
No full textThis review sets out to describe and discuss the synthetic approaches and the fields of application of PEGylated chitosan copolymers especially for medical use. The PEGylation of chitosan and chitosan derivatives is able to add new physicochemical properties to the cationic polysaccharide polymers, thereby overcoming some limitations, especially regarding their solubility and their use in drug and gene delivery (DNA and siRNA). All methods of derivatization have been considered and described together with the different methods of characterization of the copolymers. The capacities of PEGylated chitosan to reduce chitosan toxicity, to enhance membrane permeation and to form thermosensitive hydrogels have also been discussed
Effect of PEGylation on the toxicity and permeability enhancement of chitosan
No full textThe aim of the present work is to investigate if conditions can be devised where PEGylation of chitosan would reduce its toxicity toward the nasal mucosa while maintaining its ability to open the cellular tight junctions and, consequently, produce an enhancement of macromolecular permeability. A series of mPEG-g-chitosan copolymers with varying levels of mPEG substitution, mPEG molecular weight, and chitosan molecular weight were synthesized by grafting carboxylic acid-terminated mPEGs (M w 1.9 and 5.0 × 10 3 g mol -1) to chitosans (M w 28.9 and 82.0 × 10 3 g mol -1) using a NHS/EDC coupling system. The synthesized mPEG-g-chitosans were fully characterized using a number of techniques, including FT-IR, 1H NMR, and SEC-MALLS and their physicochemical properties were analyzed by TGA and DSC. Thereafter, the conjugates were tested for their cytotoxicity and tight junction modulating property in a relevant cell model, a mucus producing Calu-3 monolayer. mPEG-g-chitosan conjugates exhibited reduced toxicity toward cells, as compared to unmodified chitosan counterparts. Furthermore, the conjugates demonstrated a dramatic effect on cell monolayer transepithelial electrical resistance (TEER) and enhancement of permeability of model macromolecules. TEER and permeability-enhancing effects, as measurable indicators of tight junction modulation, were found to be pH-dependent and were notably more pronounced than those exhibited by unmodified chitosans. This work therefore demonstrates that conditions can be contrived where PEGylation improves the toxicity profile of chitosan, while preserving its effect on epithelial tight junctions in the nose
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