1,721,029 research outputs found
Biogenic amines profile and concentration in commercial milks for infants and young children
No full textCommercial milks for infants and young children (CMIYC) received much attention during last years for their impact on the nutritional status, health and development of the new-born and babies. Among possible contaminants contained in these foods, biogenic amines (BAs) have rarely been determined although they can exert toxic effects in humans if ingested at high concentrations. Spermine, spermidine, putrescine, histamine, tyramine, β-phenylethylamine and cadaverine have been quantified in CMIYC samples by LC-UV after derivatisation with dansyl-chloride. Once optimised in terms of linearity (R 2 ≥ 0.989), recovery percentages (92.9–97.3), LOD (0.2–0.4 μg g −1 or 0.03–0.05 μg mL −1 depending on the samples), LOQ (0.5–1.0 μg g −1 and 0.08–0.13 μg mL −1 depending on the samples) and repeatability (0.1–0.2 intra-day; 0.2–0.4 inter-day), the method has been applied to real samples. Very low total BAs concentrations have been found in reconstituted (1.18–3.12 mg L −1 ) and liquid milks (0.33–2.30 mg L −1 ), with different biogenic amine profiles and distributions. A risk assessment based on the available information regarding Acute Reference Doses of histamine and tyramine, as well as the application of common Biogenic Amine Indexes, showed that none of the analysed samples represented a possible risk for babies, also considering a worst case evaluation. These findings confirmed the strict safety and quality protocols adopted during the production of CMIYC. Chemical compounds studied in this article: Ammonium chloride (PubChem CID: 25517); Cadaverine hydrochloride (PubChem CID: 5351467); Hydrochloridric acid (PubChem CID: 313); Histamine dihydrochloride (PubChem CID: 5818); Phenylethylamine hydrochloride (PubChem CID: 9075); Putrescine dihydrochloride (PubChem CID: 9532); Sodium hydroxide (PubChem CID: 14798); Spermine tetrahydrochloride (PubChem CID: 1103); Spermidine trihydrochloride (PubChem CID: 1102); Tyramine hydrochloride (PubChem CID: 66449)
Molecularly Imprinted Polymers Based On Amidic Functional Monomers For Selective Recognition Of Cholesterol In Aqueous Media
No full textThe aim of this work was to investigate the possibility of employing
amidic functional monomers for the preparation of Molecularly
Imprinted Polymers (MIPs) able to bind selectively cholesterol in aqueous
media. For this purpose, Acrylamide and N,N-Dimethylacrylamide were
employed in order to maximize the hydrogen bound forming both in
pre-polymerization complex and in rebinding experiments which were
performed in polar solvents; in particular, an acetonitrile:water (7:3 v/
v) mixture was employed. The so obtained matrices showed a good
binding capacity towards the template molecule, they bound, indeed,
much more cholesterol than the corresponding non-imprinted ones.
Finally, the polymers affinity for cholesterol and its selectivity using two
steroids quite similar to cholesterol such as progesterone and
hydrocortisone. The synthesized materials, showed a good selectivity,
because they recognised less effectively the two analogues
BIOMACROMOLECULES IN RADICAL PROCESSES: INNOVATIVE STRATEGIES FOR THE SYNTHESIS OF BIOMATERIALS
No full textNatural polymers, such as polysaccharides and proteins, are materials extensively investigated due to their biocompatibility, biodegradability and non-toxic and non-immunogenic characteristics. Enclosing the biomacromolecules, in a complex structure, these features can be transferred to a biomaterial in order to extend the performance of the device. Basically, the synthesis of bioconjugates, by insertion of natural polymers in a macromolecular network by radical polymerization processes, can be achieved employing two different synthetic approaches. The first method involves the chemical modification of the biomacromolecules to introduce functionality able to undergo radical polymerization reactions. In addition, polysaccharides and proteins, without any functional changes, can take part in graft radical polymerization reactions that involve the heteroatoms of the substrates. Both synthetic approaches allows to prepare biocompatible bioconjugates showing improved physico-chemical and mechanical properties respect to the starting natural species. Furthermore, radical polymerization of biomacromolecules with monomeric species bearing specific functionality, carry out to the synthesis of polymeric network that undergo a phase transition process in response to external stimuli changes (temperature, pH, magnetic and electric field). These findings showed that the radical polymerization techniques, improving the performance of natural polymer, represent an innovative tools for the preparation of macromolecular devices potentially useful in pharmaceutical and biomedical field
Synthesis of protein-based hydrogel for pharmaceutical and biomedical applications
No full textNatural polymers, such as proteins, are materials extensively investigated due to their biocompatibility, biodegradability and non-toxic and non-immunogenic characteristics. Enclosing these biomacromolecules in a complex structure, these features can be transferred to a biomaterial in order to extend the performance of the device. Thus, the covalent conjugation of a biodegradable macromolecule, as a protein, represents a versatile strategy to produce intelligent biodegradable hydrogels, suitable for pharmaceutical and biomedical applications. The cross-linking of biomacromolecules is somewhat important in these fields because it increase the mechanical properties of the hydrogels without to affect, in severe degree, the biodegradability. Basically, albumin and gelatin represents the protein mainly used in the biomedical field and their insertion in a polymeric network was performed employing different synthetic strategy involving the functional groups in the side chain of the polypeptides. Hydrogel containing proteic moieties in the polymeric network can be achieved by thermal denaturation of the protein either by direct reaction between functional groups (usually carboxyl and amino goups) in the polypeptide side chains and also by use chemical cross-linking agents as bifunctional carbonyl reagents. Finally, involving the protein in a radical process innovative synthetic procedures were proposed in order to modify polymeric network composition and to design hydrogels with appropriate and mouldable physicochemical properties
Temperature-sensitive hydrogels by graft polymerization of chitosan and N-isopropylacrylamide for drug release
No full textThermo-responsive polysaccharidic hydrogels were designed and synthesized by a free radical induced grafting procedure. Chitosan was chosen as biopolymer to impart biocompatibility and biodegradability to the macromolecular systems, while N-isopropylacrylamide (NIPAAm) was selected as co-monomer responsive for the thermo-sensitive properties. Ammonium persulfate was the initiator system and different polymeric networks have been synthesized by modulating the amount of NIPAAm in the polymerization feed. The resulting hydrogels were proposed as drug delivery devices and their performance was evaluated by using Diclofenac sodium salt as a model drug. Hydrogels were carefully characterized by FT-IR spectrophotometry, calorimetric analyses and swelling behavior in a temperature range of 15-45 degrees C. Finally, to verify the suitability of these hydrogels as thermo-responsive devices, the drug release profiles were studied performing in vitro experiments around the swelling-shrinking transition temperatures of the macromolecular systems
Grafted thermo-responsive gelatin microspheres as delivery systems in triggered drug release
No full textIn this paper, a novel class of microspheric hydrogels was synthesized by grafting of N-isopropyacrylamide (NIPAAm) with gelatin. The possibility of inserting commercial gelatin in a crosslinked structurebearing thermo-sensitive moieties, by radical process, represents an interesting innovation that signifi-cantly improves the device performance, opening new applications in biomedical and pharmaceuticalfields. This synthetic approach allows a modification of the polymeric network composition, producinghydrogels with suitable physico-chemical properties and a transition temperature higher than NIPAAmhomopolymers. The incorporation of monomers into the network was confirmed by infrared spectroscopy, and the composition of the polymerization feed was found to strictly influence the network densityand the shape of hydrogels. Thermal analyses showed negative thermo-responsive behaviour withshrinking/swelling transition values in the temperature range 34.6–34.8 C, according to the amount ofthe hydrophilic portions in the network. In order to test the preformed materials as drug carriers, diclofenac sodium salt was loaded into the spherical microparticles. After the determination of the drug entrapment percent, drug release profiles in media at different temperature were analysed. By using semiempirical equations, the release mechanism was extensively studied and the diffusional contributionwas evaluated
Grafted gelatin microspheres as potential pH-responsive devices
No full textThis study describes the synthesis of polymericmicrospheres by reversed-phase graft polymerization ofnative gelatin (GL) and sodium methacrylate, which areuseful as stimuli-responsive drug delivery devices. Bymeans of varying the GL/functional monomer ratios(2.0–0.5 w/w), formulations with different crosslinkingdegrees, dimensional distributions, and water affinities were synthesized. The hydrogels showed spherical shape,porous surface, and high water affinity at neutral pH value with respect to the acidic conditions, with the ratio between the swellings, at pH 7.0 and 1.0, being in the range 3.7–5.1. In vitro release studies, using iclofenac sodium salt, in neutral and acidic media, simulating biological fluids, were performed. For all formulations, low amounts of drug (Mt/M0 percent \20.0%) are released in acidic medium.When the pH is 7.0, the swelling of the network increases, and the drug molecules diffuse through the polymeric structure. By means of semi-empirical equations, the release mechanism was studied, and the diffusional contribute was evaluated
Thermo-responsive albumin hydrogels with LCST near the physiological temperature
No full textThis paper deals with the synthesis of thermoresponsive microspheres with proteic structure exhibiting a transition temperature close to the body temperature. The hydrogels were synthesized by free radical polymerization of methacrylate Bovine Serum Albumin (BSA-MA) as crosslinker, and 2-hydroxyethyl methacrylate (HEMA) and/or N-isopropylacrylamide (NIPAAm), as hydrophilic and thermoresponsive monomers, respectively. The modification of the hydrophilic/hydrophobic balance in the polymerization feed allows to modulate the volume phase transition temperature of the macromolecular network. The hydrogels were characterized by infrared spectroscopy and thermal analyses, which showed negative thermoresponsive behavior for all compositions and, by increasing the content of the hydrophilic moieties in the network, the transition temperature was ranged from 34.2 to 36.8°C. To test the preformed materials as drug carriers, diclofenac diethyl ammonium salt was chosen and drug entrapment percent was determined. Drug release profiles, in media at different temperature, depend on the crosslinking degree and on the composition of the hydrogels. By using semiempirical equations, the release mechanism was extensively studied and the diffusional contribute evaluated. The physic-chemical characteristics of thermoresponsive materials confirm the applicability of the microspheres as drug delivery device
Cotton gauze-hydrogel composites: Valuable tools for electrically modulated drug delivery
No full textCotton gauze was inserted into a hydrogel network composed of acrylamide, sodium methacrylate, and polyethylene glycol dimethacrylate to fabricate an electroresponsive delivery system for wound dressing. The composite was characterized by swelling measurements, showing that shrinking or swelling depend on the applied voltage. The release profile of incorporated diclofenac sodium salt shows the possibility to modulate the kinetics by changes in the amplitude and duration of applied electric pulses. Mathematical models allow a characterization of release profiles, which are slower when an external voltage of 6, 12, and 18 V is applied, and faster at 24 V
Surface modifications of molecularly imprinted polymers for improved template recognition in water media
No full textNew Restricted Access Materials-Molecularly Imprinted Polymers (RAM-MIP) were synthesized by using caffeine (CAFF), methacrylic acid (MAA), divinyl benzene (DVB) and glycidil methacrylate (GMA) as model template, functional monomer, crosslinking agent and pro-hydrophilic co-monomer, respectively. Furthermore, a screening of the ratio of functional monomer to template was performed. After the preliminary characterizations of conventional MIP prepared in absence of GMA, different GMA amounts were inserted in the pre-polymerization feeds and different reactions conditions were tested for GMA epoxide ring opening. In particular, perchloric acid, ammonia, lactic acid, glycine and triethylene glycol were chosen for this purpose. In perchloric acid and ammonia cases, a further modification was performed by phosphorylation and methylation procedures, respectively. Imprinting efficiency of all the obtained materials was evaluated by binding experiments using caffeine and its analogue theophylline both in organic and in water media. The increased hydrophilic characteristics of RAM polymers by water absorption measurement and protein binding experiments were performed
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