Marieta Constantin - Academia.edu (original) (raw)

Papers by Marieta Constantin

Gels, Dec 13, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Materials Chemistry and Physics

Memoirs of the Scientific Sections of the Romanian Academy, 2020

Hydrogels which adjust their properties in response to environmental factors such as temperature,... more Hydrogels which adjust their properties in response to environmental factors such as temperature, pH and ionic strength are rapidly evolving, being known as smart materials. A functional monomer, 3-(trimethoxysilyl) propylmethacrylate (TSPM) with methoxysilyl group (-SiOCH3) was copolymerized with N-isopropylacrylamide (NIPAAm), acrylamide (AAm) and N,N'-methylene-bis-acrylamide (Bis), to yield a thermo-sensitive hydrogel [P(NIPAAm-co-AAm-co-TSPM)]. After treatment with NaOH (0.1 M), these hybrid hydrogels became anionically charged, due to ionisation of silanol and carboxylic groups from hydrolysed TSPM and AAm, respectively. Hydrogel morphology, before and after hydrolysis, as well as the physico-chemical properties, before and after Methylene Blue (MB) loading, were investigated by Scanning Electron Microscopy (SEM), Fourier-transform infrared (FTIR) and Ultraviolet-visible (UV) spectroscopy. The ionized hybrid hydrogels showed delayed release profiles compared to conventiona...

Polymers, 2021

A thermosensitive copolymer composed of amphiphilic triblock copolymer, poloxamer 407, grafted on... more A thermosensitive copolymer composed of amphiphilic triblock copolymer, poloxamer 407, grafted on hydrophilic pullulan with pendant carboxymethyl groups (CMP) was prepared and characterized. The structure of the new copolymer was assessed by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. The content of the poloxamer in the grafted copolymer was 83.8% (w/w). The effect of the copolymer concentration on the gelation behavior was analyzed by the vertical method and rheological tests; the gel phase of the copolymer occurred at a lower concentration (11%, w/v) as compared with poloxamer (18%, w/v). The starting gelation time under the simulated physiological conditions (phosphate buffer with a pH of 7.4, at 37 °C) was sensitive on the rest temperature before the test, this being 990 s and 280 s after 24 h rest at 4 °C and 20 °C, respectively. The rheological tests evidenced a high elasticity and excellent ability of the copolymer to recover th...

International Journal of Biological Macromolecules, 2020

A new amphiphilic pullulan derivative (DBAP-PO) was obtained by grafting tertiary butyl amine and... more A new amphiphilic pullulan derivative (DBAP-PO) was obtained by grafting tertiary butyl amine and octanoyl groups on the pullulan backbone as cationic and hydrophobic moieties, respectively. The structural characteristics of the modified polymer were investigated by FT-IR and 1 H and 13 C NMR spectroscopy. The self-association ability in aqueous solution of DBAP-PO was studied by viscosity and fluorescence methods. The intrinsic viscosity of the polymer was determined by Wolf model. The critical aggregation concentration (CAC) value of 0.028 g/dL, determined by fluorescence measurements in the presence of pyrene, was confirmed by capillary viscosimetry and dynamic laser scattering (DLS). Dialysis method was used to demonstrate the capacity of the pullulan derivative to form spherical nanoparticles (d~200 nm) loaded with model drug, sodium diclofenac (DF) (74% entrapment efficiency). The DF release was sustained and pH-dependent. In vitro cytotoxicity as well as morphological studies conducted on the human skin fibroblasts showed that DBAP-PO/DF nanoparticles do not exhibit cytotoxic effects at the pharmacologically relevant concentration of DF, maintaining the typical morphology of the cells.

Macromolecular Research, 2017

Linear statistic N-isopropylacrylamide copolymer containing 16.8 mol % of methacrylic acid was st... more Linear statistic N-isopropylacrylamide copolymer containing 16.8 mol % of methacrylic acid was studied using methods of static and dynamic light scattering and turbidimetry. The experiments were performed in aqueous solutions at the concentration c = 0.015 g cm-3 in a wide temperature region from 10 to 60 °C within pH interval from 1.7 to 11.2. The rapid increase of scattered light intensity and decrease of the transmitted light intensity at heating of the solution was observed, which implied phase separation in the solution. The phase separation was confirmed by intensive aggregation of macromolecules, which was evidenced by dramatic changes in the size of the dissolved species and their fraction in the solution. Thermoresponsiveness of the copolymer was strongly dependent on pH. The specific behavior of the N-isopropylacrylamide with methacrylic acid copolymer as compared to that with maleic acid was shown, which is caused by the presence of hydrophobic methyl group in the chemical structure of the methacrylic acid monomer.

Reactive and Functional Polymers, 2016

Water-in-oil-in-water (w 1 /o/w 2) solvent evaporation method is a technique for encapsulation an... more Water-in-oil-in-water (w 1 /o/w 2) solvent evaporation method is a technique for encapsulation and protection of water soluble and chemically sensitive bioactive molecules. One of the most important disadvantages of this method is the diffusion of bioactive molecule, during synthesis, from the primary to the secondary aqueous phase, reducing dramatically the encapsulation yield. Therefore, dexamethasone sodium phosphate (DM), a corticosteroid water soluble drug, which is sensitive to degradation, was first complexed with hydroxypropyl cyclodextrin (HPCD), γ-cyclodextrin (γ-CD) or polyethyleneimine (PEI) and then entrapped in poly(lactic-co-glycolic acid) (PLGA) microspheres obtained by w 1 /o/w 2 solvent evaporation method. Association equilibrium constants for the formation of the HPCD/DM and γ-CD/DM inclusion complexes were also calculated, being 1.420 × 10 3 M −1 and 1.447 × 10 4 M −1 , respectively. PEI was proved to be the most efficient DM trapper, retaining the highest amount of the drug in microspheres, followed by γ-CD and HPCD. Despite the high values of the association equilibrium constants for DM binding to HPCD and γ-CD, both cyclodextrins are not able to protect the drug against UV irradiation. The morphology of the microspheres as well as the drug entrapment efficiency and the release rates are influenced by complexing agents and the ratio between the primary aqueous phase and the organic phase.

Gels

PVA/chitosan (PVA/CS) composite hydrogels incorporating silver nanoparticles (AgNPs) were prepare... more PVA/chitosan (PVA/CS) composite hydrogels incorporating silver nanoparticles (AgNPs) were prepared by double-cross-linked procedures: freeze–thawing and electrostatic interactions. Oxalic acid (OA) was used both for solubilization and ionic cross-linking of CS. AgNPs covered by CS (CS-AgNPs) with an average diameter of 9 nm and 18% silver were obtained in the presence of CS, acting as reducing agent and particle stabilizer. The increase of the number of freeze–thaw cycles, as well as of the PVA:CS and OA:CS ratios, resulted in an increase of the gel fraction and elastic modulus. Practically, the elastic modulus of the hydrogels increased from 3.5 kPa in the absence of OA to 11.6 kPa at a 1:1 OA:CS weight ratio, proving that OA was involved in physical cross-linking. The physicochemical properties were not altered by the addition of CS-AgNPs in low concentration; however, concentrations higher than 3% resulted in low gel fraction and elastic modulus. The amount of silver released fro...

Expert Opinion on Drug Delivery

Polymers

The goal of the current article was to obtain data regarding the application of a series of graft... more The goal of the current article was to obtain data regarding the application of a series of grafted pullulan derivatives, as flocculating agents, for removal of some pesticide formulations from model wastewater. The pullulan derivatives are cationic polyelectrolytes, with various content and length of grafted poly[(3-acrylamidopropyl)-trimethylammonium chloride] chains onto the pullulan (P-g-pAPTAC)]. The commercial pesticides are either fungicide (Bordeaux Mixture) (BM) or insecticides (Decis (Dc)—active ingredient Deltamethrin, Confidor Oil (CO)—active ingredient Imidacloprid, Confidor Energy (CE)—active ingredients Deltamethrin and Imidacloprid and Novadim Progress (NP)—active ingredient Dimethoate). The removal efficiency has been assessed by UV-Vis spectroscopy measurements as a function of some parameters, namely polymer dose, grafted chains content and length, pesticides concentration. The P-g-pAPTAC samples showed good removal efficacy at doseop, more than 94% for BM, betwee...

International Journal of Biological Macromolecules, 2021

Hydrogel-based wound dressings have been intensively studied as promising materials for wound hea... more Hydrogel-based wound dressings have been intensively studied as promising materials for wound healing and care. The mixed-mode thiol-acrylate photopolymerization is used in this paper for alginate/poloxamer hydrogels formation. First, the alginate was modified with thiol groups using the esterification reaction with cysteamine, and second, the terminal hydroxyl groups of poloxamer were esterified with acryloyl chloride to introduce polymerizable acrylate groups. Finally, the cross-linking reaction between the two macromers was performed to produce degradable alginate/poloxamer hydrogels. The optimum conditions for the photo-initiated reaction were studied in order to obtain high gel fractions. The resulting hydrogels have high swelling capacity in simulated physiological conditions, good elasticity and strength, and appropriate porosity, some of the physico-chemical properties required for their applications as wound dressings/patches. The biological assays show that the alginate/poloxamer hydrogels induce proliferation of human keratinocyte and have an anti-inflammatory effect on lipopolysaccharides (LPS)-activated keratinocytes by inhibiting the extracellular signal-regulated kinases (ERK)/ nuclear factor (NF)-kB/ tumor necrosis factor (TNF)-α signalling pathway. Taken together, the results showed that the chemical cross-linked alginate/poloxamer hydrogels may function as a dressing/patch applied directly on the skin lesion to heal the wound by reducing the exacerbated inflammation, the main cause of wound healing delay and local infection.

Polymers

Local delivery of drugs or antimicrobial agents is a suitable approach in the management of perio... more Local delivery of drugs or antimicrobial agents is a suitable approach in the management of periodontitis when the infection is localized deep in the pockets and does not adequately respond to mechanical debridement and/or systemic antibiotic treatment. In this context, the objective of this study was to prepare new biocomposite films with antimicrobial, anti-inflammatory, and good mechanical properties to be applied in periodontal pockets. The composite film is eco-friendly synthesized from poly(vinyl alcohol) (PVA) cross-linked with oxidized chitosan (OxCS). Silver nanoparticles (AgNps) were inserted during film synthesis by adding freshly chitosan-capped AgNps colloidal solution to the polymer mixture; the addition of AgNps up to 1.44 wt.% improves the physico-chemical properties of the film. The characterization of the films was performed by FT-IR, atomic mass spectrometry, X-ray spectroscopy, and SEM. The films displayed a high swelling ratio (162%), suitable strength (1.46 MPa...

Journal of Molecular Liquids

New Trends in Macromolecular and Supramolecular Chemistry for Biological Applications, 2021

Smart polymers or polymers sensitive to external stimuli are remarkable materials because they be... more Smart polymers or polymers sensitive to external stimuli are remarkable materials because they behave similarly to living organisms. Basically, these polymers as linear molecules or cross-linked networks modify their physico-chemical properties such as hydrophilic/ hydrophobic balance, solubility, degree of swelling in response to the action of external stimuli present in the human body. Among stimuli-sensitive polymers, those sensitive to pH and temperature are the most useful in biomedical area because in the human body, these physico-chemical parameters change in different body compartments. All of these changes were exploited to control the moment and release rates of drugs. Moreover, these systems have the ability of reacting to the presence of biomolecules released by the body under pathological conditions.

Reactive & Functional Polymers, 2021

The idea that pH decreases significantly in tumors is widespread, however recent progress in the ... more The idea that pH decreases significantly in tumors is widespread, however recent progress in the measurement of pH in cancer tissues has revealed that the intracellular pH of cancer cells is neutral or even mildly alkaline compared to normal tissues [Hao et al., 2018]. However, in both cancer and normal cells the pH drops from 6.0–5.5 in endosomes to 5.0 in lysosomes after particle internalization by EPR effect. Here, the design of “intelligent” delivery systems able to exploit these pH variations is reported. Poly(N-isopropylacrylamide-co-4-vinylpyridine) (poly(NIPAAm-co-4-VP)) was synthesized and characterized as an exciting pH/temperature sensitive copolymer with a pKa value of 5.05. The lower critical solution temperature (LCST) of the copolymer was determined at physiological conditions (phosphate buffer (PB) at pH = 7.4 and 36 °C), and at acidic pH values similarly to those of cell compartments. Values of LCST of the copolymer with the co-monomer molar ratio of 86:14 (NIPAAm:4...

Journal of Polymer Research, 2021

N-acryloyl-L-valine (AV) was synthesized as a pH-sensitive monomer possessing both acrylamide and... more N-acryloyl-L-valine (AV) was synthesized as a pH-sensitive monomer possessing both acrylamide and isopropyl sequences similar to the chemical architecture of N-isopropylacrylamide (NIPAAm). Poly(NIPAAm-co-AV) copolymer contained 5.03 mol % randomly introduced AV units was prepared and analyzed. The sample with molar mass Mw = 24,000 g/mol was studied in aqueous solutions using static and dynamic light scattering and optical transmittance methods. Temperature dependences of scattered light intensity and turbidity as well as hydrodynamic radii of dissolved species and their relative contributions to the light scattering were obtained to determine the temperatures of phase separation in aqueous media of various acidities. The dependence of the phase separation onset temperatures on pH corresponded to that obtained for anionic pH-responsive polymers. Aggregated structures were observed in solutions; moreover, in a strongly acidic medium, with an increase in temperature, the compaction of aggregates predominated, and with an increase in pH, the formation of new aggregates dominated over their compaction.

Environmental Challenges, 2021

Journal of Polymer Research, 2021

Calcium-pectin beads are largely used for biomedical applications, however, the main drawback is ... more Calcium-pectin beads are largely used for biomedical applications, however, the main drawback is their rapid disintegration in the presence of chelating and non-chelating ions from body fluids. Therefore, the principal goal of this work is to produce stable pectin beads by successive ionic and covalent cross-linking and to test their stability in simulated physiological conditions. For this purpose, native pectin was first de-esterified (DEP) to result a maximum amount of carboxylic groups, then a fraction of the DEP was oxidized with NaIO4 (OXP) to introduce aldehyde groups susceptible to covalent cross-linking. Finally, the de-methylated and de-methylated/oxidized pectin were mixed and transformed into beads by double cross-linking: ionic with calcium ions and covalent with adipic acid dihydrazide (ADH). The gelling properties, sphericity and shape as well as the morphology and the stability of the beads in different media were investigated. Finally, beads were tested for their capacity to encapsulate and release drug molecule. Therefore, microcapsules were loaded with FITC-dextran, a standard high molecular weight model drug molecule, with high encapsulation efficiency. A remarkable delay in FITC-dextran release was observed for DEP/OXP beads compared to DEP particles. The transport mechanism of solvent and FITC-dextran in/from the DEP/OXP beads was determined as a Fickian diffusion-driven. The viability tests proved that both simple and double cross-linked microcapsules are cytocompatible for the HEK-293 cells at pectin concentrations up to 5.5 mg/mL.

Environmental Engineering and Management Journal, 2019

The synthesis of dimethylamino-propylamine pullulan, DMAPA-P, with a substitution degree of 0.4 w... more The synthesis of dimethylamino-propylamine pullulan, DMAPA-P, with a substitution degree of 0.4 was performed in dimethylsulfoxide using N,N'-carbonyldiimidazole as activator and dimethylaminopropylamine as amination agent. Then, two quaternary derivatives (trimethylammonium-propylamine pullulan, TMAPA-P, and benzyldimethylammonium-propylamine pullulan, BzDMAPA-P) were prepared from DMAPA-P by quaternization with methyl iodide and benzyl chloride. The behavior of new pullulan derivatives solution containing tertiary amine or quaternary ammonium groups in different polar solvents (protic or aprotic) with added low molecular salt was studied by laser light scattering. Thus, all polymers recorded positive second virial coefficients A2 in solvents with 0.5 M salt added, and molecular masses for TMAPA-P and BzDMAPA-P increased compared with them precursor DMAPA-P. Finally, these polysaccharide derivatives (alone or in tandem with NaCl) were tested for their capacity to remove inorganic materials from synthetic turbid water. Turbidity of aqueous bentonite solutions in the presence of BzDMAPA-P or DMAPA-P increased compared with turbidity of bentonite solutions. Remarkably, the addition of NaCl improved the inorganic particles settling capacity of all three polysaccharides.

Journal of Macromolecular Science, Part B, 2019

Statistical copolymers of N-isopropylacrylamide containing 2.2-2.7 mol % D,L-allylglycine were sy... more Statistical copolymers of N-isopropylacrylamide containing 2.2-2.7 mol % D,L-allylglycine were synthesized. The sample with 2.2 mol % allylglycine and molar mass 320000 g/mol was studied using light scattering and turbidimetry while heated in water and water-salt solutions. Temperature dependencies of light scattering intensity and optical transmission as well as hydrodynamic size and composition of the scattering entities were obtained in a wide range of pH. The onset temperatures of phase separation were independent of pH; however, in the basic pH region the phase transition was widened as compared to the neutral and acid media. It was shown that a small content of allylglycine results in a different thermoresponsive behavior of the copolymer as compared with N-isopropylacrylamide homopolymer. The addition of a physiological amount of NaCl shifts the copolymer thermo-sensitivity toward lower temperatures.

Gels, Dec 13, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Materials Chemistry and Physics

Memoirs of the Scientific Sections of the Romanian Academy, 2020

Hydrogels which adjust their properties in response to environmental factors such as temperature,... more Hydrogels which adjust their properties in response to environmental factors such as temperature, pH and ionic strength are rapidly evolving, being known as smart materials. A functional monomer, 3-(trimethoxysilyl) propylmethacrylate (TSPM) with methoxysilyl group (-SiOCH3) was copolymerized with N-isopropylacrylamide (NIPAAm), acrylamide (AAm) and N,N'-methylene-bis-acrylamide (Bis), to yield a thermo-sensitive hydrogel [P(NIPAAm-co-AAm-co-TSPM)]. After treatment with NaOH (0.1 M), these hybrid hydrogels became anionically charged, due to ionisation of silanol and carboxylic groups from hydrolysed TSPM and AAm, respectively. Hydrogel morphology, before and after hydrolysis, as well as the physico-chemical properties, before and after Methylene Blue (MB) loading, were investigated by Scanning Electron Microscopy (SEM), Fourier-transform infrared (FTIR) and Ultraviolet-visible (UV) spectroscopy. The ionized hybrid hydrogels showed delayed release profiles compared to conventiona...

Polymers, 2021

A thermosensitive copolymer composed of amphiphilic triblock copolymer, poloxamer 407, grafted on... more A thermosensitive copolymer composed of amphiphilic triblock copolymer, poloxamer 407, grafted on hydrophilic pullulan with pendant carboxymethyl groups (CMP) was prepared and characterized. The structure of the new copolymer was assessed by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. The content of the poloxamer in the grafted copolymer was 83.8% (w/w). The effect of the copolymer concentration on the gelation behavior was analyzed by the vertical method and rheological tests; the gel phase of the copolymer occurred at a lower concentration (11%, w/v) as compared with poloxamer (18%, w/v). The starting gelation time under the simulated physiological conditions (phosphate buffer with a pH of 7.4, at 37 °C) was sensitive on the rest temperature before the test, this being 990 s and 280 s after 24 h rest at 4 °C and 20 °C, respectively. The rheological tests evidenced a high elasticity and excellent ability of the copolymer to recover th...

International Journal of Biological Macromolecules, 2020

A new amphiphilic pullulan derivative (DBAP-PO) was obtained by grafting tertiary butyl amine and... more A new amphiphilic pullulan derivative (DBAP-PO) was obtained by grafting tertiary butyl amine and octanoyl groups on the pullulan backbone as cationic and hydrophobic moieties, respectively. The structural characteristics of the modified polymer were investigated by FT-IR and 1 H and 13 C NMR spectroscopy. The self-association ability in aqueous solution of DBAP-PO was studied by viscosity and fluorescence methods. The intrinsic viscosity of the polymer was determined by Wolf model. The critical aggregation concentration (CAC) value of 0.028 g/dL, determined by fluorescence measurements in the presence of pyrene, was confirmed by capillary viscosimetry and dynamic laser scattering (DLS). Dialysis method was used to demonstrate the capacity of the pullulan derivative to form spherical nanoparticles (d~200 nm) loaded with model drug, sodium diclofenac (DF) (74% entrapment efficiency). The DF release was sustained and pH-dependent. In vitro cytotoxicity as well as morphological studies conducted on the human skin fibroblasts showed that DBAP-PO/DF nanoparticles do not exhibit cytotoxic effects at the pharmacologically relevant concentration of DF, maintaining the typical morphology of the cells.

Macromolecular Research, 2017

Linear statistic N-isopropylacrylamide copolymer containing 16.8 mol % of methacrylic acid was st... more Linear statistic N-isopropylacrylamide copolymer containing 16.8 mol % of methacrylic acid was studied using methods of static and dynamic light scattering and turbidimetry. The experiments were performed in aqueous solutions at the concentration c = 0.015 g cm-3 in a wide temperature region from 10 to 60 °C within pH interval from 1.7 to 11.2. The rapid increase of scattered light intensity and decrease of the transmitted light intensity at heating of the solution was observed, which implied phase separation in the solution. The phase separation was confirmed by intensive aggregation of macromolecules, which was evidenced by dramatic changes in the size of the dissolved species and their fraction in the solution. Thermoresponsiveness of the copolymer was strongly dependent on pH. The specific behavior of the N-isopropylacrylamide with methacrylic acid copolymer as compared to that with maleic acid was shown, which is caused by the presence of hydrophobic methyl group in the chemical structure of the methacrylic acid monomer.

Reactive and Functional Polymers, 2016

Water-in-oil-in-water (w 1 /o/w 2) solvent evaporation method is a technique for encapsulation an... more Water-in-oil-in-water (w 1 /o/w 2) solvent evaporation method is a technique for encapsulation and protection of water soluble and chemically sensitive bioactive molecules. One of the most important disadvantages of this method is the diffusion of bioactive molecule, during synthesis, from the primary to the secondary aqueous phase, reducing dramatically the encapsulation yield. Therefore, dexamethasone sodium phosphate (DM), a corticosteroid water soluble drug, which is sensitive to degradation, was first complexed with hydroxypropyl cyclodextrin (HPCD), γ-cyclodextrin (γ-CD) or polyethyleneimine (PEI) and then entrapped in poly(lactic-co-glycolic acid) (PLGA) microspheres obtained by w 1 /o/w 2 solvent evaporation method. Association equilibrium constants for the formation of the HPCD/DM and γ-CD/DM inclusion complexes were also calculated, being 1.420 × 10 3 M −1 and 1.447 × 10 4 M −1 , respectively. PEI was proved to be the most efficient DM trapper, retaining the highest amount of the drug in microspheres, followed by γ-CD and HPCD. Despite the high values of the association equilibrium constants for DM binding to HPCD and γ-CD, both cyclodextrins are not able to protect the drug against UV irradiation. The morphology of the microspheres as well as the drug entrapment efficiency and the release rates are influenced by complexing agents and the ratio between the primary aqueous phase and the organic phase.

Gels

PVA/chitosan (PVA/CS) composite hydrogels incorporating silver nanoparticles (AgNPs) were prepare... more PVA/chitosan (PVA/CS) composite hydrogels incorporating silver nanoparticles (AgNPs) were prepared by double-cross-linked procedures: freeze–thawing and electrostatic interactions. Oxalic acid (OA) was used both for solubilization and ionic cross-linking of CS. AgNPs covered by CS (CS-AgNPs) with an average diameter of 9 nm and 18% silver were obtained in the presence of CS, acting as reducing agent and particle stabilizer. The increase of the number of freeze–thaw cycles, as well as of the PVA:CS and OA:CS ratios, resulted in an increase of the gel fraction and elastic modulus. Practically, the elastic modulus of the hydrogels increased from 3.5 kPa in the absence of OA to 11.6 kPa at a 1:1 OA:CS weight ratio, proving that OA was involved in physical cross-linking. The physicochemical properties were not altered by the addition of CS-AgNPs in low concentration; however, concentrations higher than 3% resulted in low gel fraction and elastic modulus. The amount of silver released fro...

Expert Opinion on Drug Delivery

Polymers

The goal of the current article was to obtain data regarding the application of a series of graft... more The goal of the current article was to obtain data regarding the application of a series of grafted pullulan derivatives, as flocculating agents, for removal of some pesticide formulations from model wastewater. The pullulan derivatives are cationic polyelectrolytes, with various content and length of grafted poly[(3-acrylamidopropyl)-trimethylammonium chloride] chains onto the pullulan (P-g-pAPTAC)]. The commercial pesticides are either fungicide (Bordeaux Mixture) (BM) or insecticides (Decis (Dc)—active ingredient Deltamethrin, Confidor Oil (CO)—active ingredient Imidacloprid, Confidor Energy (CE)—active ingredients Deltamethrin and Imidacloprid and Novadim Progress (NP)—active ingredient Dimethoate). The removal efficiency has been assessed by UV-Vis spectroscopy measurements as a function of some parameters, namely polymer dose, grafted chains content and length, pesticides concentration. The P-g-pAPTAC samples showed good removal efficacy at doseop, more than 94% for BM, betwee...

International Journal of Biological Macromolecules, 2021

Hydrogel-based wound dressings have been intensively studied as promising materials for wound hea... more Hydrogel-based wound dressings have been intensively studied as promising materials for wound healing and care. The mixed-mode thiol-acrylate photopolymerization is used in this paper for alginate/poloxamer hydrogels formation. First, the alginate was modified with thiol groups using the esterification reaction with cysteamine, and second, the terminal hydroxyl groups of poloxamer were esterified with acryloyl chloride to introduce polymerizable acrylate groups. Finally, the cross-linking reaction between the two macromers was performed to produce degradable alginate/poloxamer hydrogels. The optimum conditions for the photo-initiated reaction were studied in order to obtain high gel fractions. The resulting hydrogels have high swelling capacity in simulated physiological conditions, good elasticity and strength, and appropriate porosity, some of the physico-chemical properties required for their applications as wound dressings/patches. The biological assays show that the alginate/poloxamer hydrogels induce proliferation of human keratinocyte and have an anti-inflammatory effect on lipopolysaccharides (LPS)-activated keratinocytes by inhibiting the extracellular signal-regulated kinases (ERK)/ nuclear factor (NF)-kB/ tumor necrosis factor (TNF)-α signalling pathway. Taken together, the results showed that the chemical cross-linked alginate/poloxamer hydrogels may function as a dressing/patch applied directly on the skin lesion to heal the wound by reducing the exacerbated inflammation, the main cause of wound healing delay and local infection.

Polymers

Local delivery of drugs or antimicrobial agents is a suitable approach in the management of perio... more Local delivery of drugs or antimicrobial agents is a suitable approach in the management of periodontitis when the infection is localized deep in the pockets and does not adequately respond to mechanical debridement and/or systemic antibiotic treatment. In this context, the objective of this study was to prepare new biocomposite films with antimicrobial, anti-inflammatory, and good mechanical properties to be applied in periodontal pockets. The composite film is eco-friendly synthesized from poly(vinyl alcohol) (PVA) cross-linked with oxidized chitosan (OxCS). Silver nanoparticles (AgNps) were inserted during film synthesis by adding freshly chitosan-capped AgNps colloidal solution to the polymer mixture; the addition of AgNps up to 1.44 wt.% improves the physico-chemical properties of the film. The characterization of the films was performed by FT-IR, atomic mass spectrometry, X-ray spectroscopy, and SEM. The films displayed a high swelling ratio (162%), suitable strength (1.46 MPa...

Journal of Molecular Liquids

New Trends in Macromolecular and Supramolecular Chemistry for Biological Applications, 2021

Smart polymers or polymers sensitive to external stimuli are remarkable materials because they be... more Smart polymers or polymers sensitive to external stimuli are remarkable materials because they behave similarly to living organisms. Basically, these polymers as linear molecules or cross-linked networks modify their physico-chemical properties such as hydrophilic/ hydrophobic balance, solubility, degree of swelling in response to the action of external stimuli present in the human body. Among stimuli-sensitive polymers, those sensitive to pH and temperature are the most useful in biomedical area because in the human body, these physico-chemical parameters change in different body compartments. All of these changes were exploited to control the moment and release rates of drugs. Moreover, these systems have the ability of reacting to the presence of biomolecules released by the body under pathological conditions.

Reactive & Functional Polymers, 2021

The idea that pH decreases significantly in tumors is widespread, however recent progress in the ... more The idea that pH decreases significantly in tumors is widespread, however recent progress in the measurement of pH in cancer tissues has revealed that the intracellular pH of cancer cells is neutral or even mildly alkaline compared to normal tissues [Hao et al., 2018]. However, in both cancer and normal cells the pH drops from 6.0–5.5 in endosomes to 5.0 in lysosomes after particle internalization by EPR effect. Here, the design of “intelligent” delivery systems able to exploit these pH variations is reported. Poly(N-isopropylacrylamide-co-4-vinylpyridine) (poly(NIPAAm-co-4-VP)) was synthesized and characterized as an exciting pH/temperature sensitive copolymer with a pKa value of 5.05. The lower critical solution temperature (LCST) of the copolymer was determined at physiological conditions (phosphate buffer (PB) at pH = 7.4 and 36 °C), and at acidic pH values similarly to those of cell compartments. Values of LCST of the copolymer with the co-monomer molar ratio of 86:14 (NIPAAm:4...

Journal of Polymer Research, 2021

N-acryloyl-L-valine (AV) was synthesized as a pH-sensitive monomer possessing both acrylamide and... more N-acryloyl-L-valine (AV) was synthesized as a pH-sensitive monomer possessing both acrylamide and isopropyl sequences similar to the chemical architecture of N-isopropylacrylamide (NIPAAm). Poly(NIPAAm-co-AV) copolymer contained 5.03 mol % randomly introduced AV units was prepared and analyzed. The sample with molar mass Mw = 24,000 g/mol was studied in aqueous solutions using static and dynamic light scattering and optical transmittance methods. Temperature dependences of scattered light intensity and turbidity as well as hydrodynamic radii of dissolved species and their relative contributions to the light scattering were obtained to determine the temperatures of phase separation in aqueous media of various acidities. The dependence of the phase separation onset temperatures on pH corresponded to that obtained for anionic pH-responsive polymers. Aggregated structures were observed in solutions; moreover, in a strongly acidic medium, with an increase in temperature, the compaction of aggregates predominated, and with an increase in pH, the formation of new aggregates dominated over their compaction.

Environmental Challenges, 2021

Journal of Polymer Research, 2021

Calcium-pectin beads are largely used for biomedical applications, however, the main drawback is ... more Calcium-pectin beads are largely used for biomedical applications, however, the main drawback is their rapid disintegration in the presence of chelating and non-chelating ions from body fluids. Therefore, the principal goal of this work is to produce stable pectin beads by successive ionic and covalent cross-linking and to test their stability in simulated physiological conditions. For this purpose, native pectin was first de-esterified (DEP) to result a maximum amount of carboxylic groups, then a fraction of the DEP was oxidized with NaIO4 (OXP) to introduce aldehyde groups susceptible to covalent cross-linking. Finally, the de-methylated and de-methylated/oxidized pectin were mixed and transformed into beads by double cross-linking: ionic with calcium ions and covalent with adipic acid dihydrazide (ADH). The gelling properties, sphericity and shape as well as the morphology and the stability of the beads in different media were investigated. Finally, beads were tested for their capacity to encapsulate and release drug molecule. Therefore, microcapsules were loaded with FITC-dextran, a standard high molecular weight model drug molecule, with high encapsulation efficiency. A remarkable delay in FITC-dextran release was observed for DEP/OXP beads compared to DEP particles. The transport mechanism of solvent and FITC-dextran in/from the DEP/OXP beads was determined as a Fickian diffusion-driven. The viability tests proved that both simple and double cross-linked microcapsules are cytocompatible for the HEK-293 cells at pectin concentrations up to 5.5 mg/mL.

Environmental Engineering and Management Journal, 2019

The synthesis of dimethylamino-propylamine pullulan, DMAPA-P, with a substitution degree of 0.4 w... more The synthesis of dimethylamino-propylamine pullulan, DMAPA-P, with a substitution degree of 0.4 was performed in dimethylsulfoxide using N,N'-carbonyldiimidazole as activator and dimethylaminopropylamine as amination agent. Then, two quaternary derivatives (trimethylammonium-propylamine pullulan, TMAPA-P, and benzyldimethylammonium-propylamine pullulan, BzDMAPA-P) were prepared from DMAPA-P by quaternization with methyl iodide and benzyl chloride. The behavior of new pullulan derivatives solution containing tertiary amine or quaternary ammonium groups in different polar solvents (protic or aprotic) with added low molecular salt was studied by laser light scattering. Thus, all polymers recorded positive second virial coefficients A2 in solvents with 0.5 M salt added, and molecular masses for TMAPA-P and BzDMAPA-P increased compared with them precursor DMAPA-P. Finally, these polysaccharide derivatives (alone or in tandem with NaCl) were tested for their capacity to remove inorganic materials from synthetic turbid water. Turbidity of aqueous bentonite solutions in the presence of BzDMAPA-P or DMAPA-P increased compared with turbidity of bentonite solutions. Remarkably, the addition of NaCl improved the inorganic particles settling capacity of all three polysaccharides.

Journal of Macromolecular Science, Part B, 2019

Statistical copolymers of N-isopropylacrylamide containing 2.2-2.7 mol % D,L-allylglycine were sy... more Statistical copolymers of N-isopropylacrylamide containing 2.2-2.7 mol % D,L-allylglycine were synthesized. The sample with 2.2 mol % allylglycine and molar mass 320000 g/mol was studied using light scattering and turbidimetry while heated in water and water-salt solutions. Temperature dependencies of light scattering intensity and optical transmission as well as hydrodynamic size and composition of the scattering entities were obtained in a wide range of pH. The onset temperatures of phase separation were independent of pH; however, in the basic pH region the phase transition was widened as compared to the neutral and acid media. It was shown that a small content of allylglycine results in a different thermoresponsive behavior of the copolymer as compared with N-isopropylacrylamide homopolymer. The addition of a physiological amount of NaCl shifts the copolymer thermo-sensitivity toward lower temperatures.