Pectin and chitosan films containing glycerol (Gly) at 5, 10, 15, 20, 30, and 40 wt % were prepared in an aqueous HCl solution (0.10 M) by the solvent evaporation method. The unwashed film (UF) ...containing 40 wt % Gly (UF40) had elongation at break (
, %) of 19%. Washed films (WFs) had high tensile strength (
> 46 MPa) and low elongation at break (
, <5.0%), enabling their use in food packaging applications. The polymers' self-assembling occurred during the washing, increasing the stiffness. The XPS analysis suggests that some HCl is lost during the drying process, resulting in a low acid content on the UF surfaces. The UF40 (at 5.0 mg/mL) exhibits cytocompatibility toward mammalian cells and antimicrobial and anti-adhesive properties against
. The remaining HCl in the UF40 can be a disadvantage for food packaging applications; the UF40 (∅ = 8.5 mm; 55 μm thickness) releases H
O
/HCl, reducing the pH to approximately 3.0 when kept in 200 mL distilled water for approximately 30 min. Therefore, we propose the use of UF40 to coat commercial food packaging. The UF40 has low permeability to water vapor and oxygen and works as a barrier against ultraviolet light. The UF40 is also colorless and completely transparent. The UF40 maintained tomatoes' structural integrity for 18 days at room temperature with no oxidation or microorganism contamination. This paper presents a critical viewpoint concerning chitosan-based films with antimicrobial activities.
Conventional strategies (Turkevich's, and modified Turkevich's methods) often synthesize gold nanoparticles (AuNPs). These pathways produce AuNPs using toxic chemistries to reduce Au(III) and ...stabilize Au(0) atoms upon the AuNP surfaces. To overcome the disadvantages of conventional approaches, chitosan and chitosan-based materials associate with Au(III) to produce composites. Chitosan and derivatives reduce Au(III) and stabilize AuNPs, promoting biocompatibility to the composites, following approaches in-situ. In this review, we report methods to develop chitosan/AuNPs-based composites. The main criticism is about the mechanism of composite formation. Also, we highlight applications of chitosan/AuNPs-based devices in the biomedical arena. We report the synthesis of biosensors, drug delivery devices, scaffolds, antimicrobial coatings, and others. The major criticism is concerning the material design and the lack of data regarding the composite biocompatibility. We support a critical viewpoint.
•The synthesis mechanism of chitosan/gold composites is investigated.•Strategies ex-situ and in-situ synthesize the composites.•Overall, the studies do not provide enough data to support composite biocompatibility.•The design of the composite is the principal challenge to create biomedical devices.
Polysaccharide-based materials created by physical processes have received considerable attention for biomedical applications. These structures are often made by associating charged polyelectrolytes ...in aqueous solutions, avoiding toxic chemistries (crosslinking agents). We review the principal polysaccharides (glycosaminoglycans, marine polysaccharides, and derivatives) containing ionizable groups in their structures and cellulose (neutral polysaccharide). Physical materials with high stability in aqueous media can be developed depending on the selected strategy. We review strategies, including coacervation, ionotropic gelation, electrospinning, layer-by-layer coating, gelation of polymer blends, solvent evaporation, and freezing-thawing methods, that create polysaccharide-based assemblies via in situ (one-step) methods for biomedical applications. We focus on materials used for growth factor (GFs) delivery, scaffolds, antimicrobial coatings, and wound dressings.
Here we report a new and straightforward method to yield durable polyelectrolyte complexes (hydrogel PECs) from gellan gum (GG) and chitosan (CS) assemblies, without metallic and covalent ...crosslinking agents, commonly used to produce GG and CS-based hydrogels, respectively. This new approach overcomes challenges of obtaining stable and durable GG-based hydrogels with structural homogeneity, avoiding precipitation and aqueous instability, typical of PEC-based materials. PECs are created by blending CS:GG solutions (at 60 °C) with GG:CS weight ratios between 80:20 to 40:60. X-ray photoelectron spectroscopy (XPS) analysis shows that CS-GG chains are interacting by electrostatic and intermolecular forces, conferring a high degree of association to the washed PECs, characteristic of self-assembling of polymer chains. The CS:GG weight ratio can be tuned to improve polyelectrolyte complex (PEC) high porosity, stability, porous homogeneity, and degradation rate. Physical and thermosensitive CS/GG-based hydrogels can have advantages over conventional materials produced by chemical processes.
•Chitosan/gellan gum polyelectrolyte complexes were prepared.•Chitosan:gellan gum weight ratio plays a significant role in the features of the materials.•The materials present stability, self-assembling, structural homogeneity and slow degradation rate.
Gelatin (GE), amino-functionalized polyphenolic tannin derivative (TN), and graphene oxide (GO) were associated to yield thermo- and pH-responsive hydrogels for the first time. Durable hydrogel ...assemblies for drug delivery purposes were developed using the photosensitizer methylene blue (MB) as a drug model. The cooling GE/TN blends provide brittle physical assemblies. To overcome this disadvantage, different GO contents (between 0.31% and 1.02% wt/wt) were added to the GE/TN blend at 89.7/10.3 wt/wt. FTIR and RAMAN spectroscopy analyses characterized the materials, indicating GO presence in the hydrogels. Incorporation studies revealed a total MB (0.50 mg/mL) incorporation into the GE/TN-GO hydrogel matrices. Additionally, the proposed systems present a mechanical behavior similar to gel. The GO presence in the hydrogel matrices increased the elastic modulus from 516 to 1650 Pa. SEM revealed that hydrogels containing MB present higher porosity with interconnected pores. Dissolution and swelling degree studies revealed less stability of the GE/TN-GO-MB hydrogels in SGF medium (pH 1.2) than SIF (pH 6.8). The degradation increased in SIF with the GO content, making the polymeric matrices more hydrophilic. MB release studies revealed a process controlled by Fickian diffusion. Our results point out the pH-responsible behavior of mechanically reinforced GE/TN-GO-MB hydrogels for drug delivery systems purposes.
Thermo- and pH-sensitive hydrogels based on chitosan (CS) and gellan gum (GG) were used for efficient curcumin (CUR) delivery for the first time. β-Cyclodextrin/curcumin (βCD/CUR) inclusion complex ...was mixed with aqueous GG solution and associated with CS solution aliquots. CS/GG hydrogels incorporated with the βCD-CUR inclusion complex containing CS between 40 and 80 wt% were prepared by cooling CS/GG/βCD/CUR mixtures. The materials were characterized by infrared spectroscopy, thermal analysis, X-ray diffraction, scanning electron microscopy, confocal scanning microscopy, and mechanical measurements. The CS/GG-βCD-CUR ratio in the mixture significantly influenced the hydrogel properties. The pH-responsive hydrogels presented porosity between 76 and 84%, mechanical strength between 247 and 747 Pa, and disintegration rate lower than 25% in simulated intestinal fluid (SIF). The CUR release was investigated in simulated intestinal (SIF) and simulated gastric (SGF) fluids with and without lysozyme (27.8 μg/mL) and Tween 80 (1% v/v). Lysozyme and Tween 80 enhanced the CUR release in SIF, reaching 69.40% (10.10 mg/g) after 240 h. The Ritger-Peppas and Higuchi mathematical models adjusted well to the experimental CUR release kinetic curves. The materials were cytocompatible toward healthy VERO cells. This study reports durable polysaccharide-based assemblies for CUR delivery created following a method in-situ.
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•Drug delivery systems based on physical chitosan/gellan gum assemblies are formed by cooling polymer mixtures.•The β-cyclodextrin/curcumin inclusion complex was incorporated in the hydrogels.•The materials were created following a strategy in situ (one-step).•The release tests were performed in simulated fluids with and without lysozyme and Tween 80.•The wet hydrogels acted as efficient curcumin delivery agents in simulated intestinal fluid.
Gelatin (GE) and chondroitin sulfate (CS) polyelectrolyte multilayers (PEMs) with or without ionic liquids (ILs) are assembled on oxidized poly(ethylene terephthalate) (PET), using the layer-by-layer ...(LbL) approach. The ILs associated with the PEMs include 1-n-hexadecyl-3-methylimidazolium chloride (C16MImCl), 1-n-hexadecyl-3-methylimidazolium methanesulfonate (C16MImMeS), and 1-n-hexadecyl pyridinium chloride monohydrate (C16PyrCl.H2O). The ILs are associated with PEMs for the first time. The ILs are dissolved in an aqueous GE solution and then associated with CS by the layer-by-layer approach. The alternating deposition of GE or GE/ILs and CS multilayers on the oxidized PET results in durable surface coatings. The oxidized PET and PEMs are characterized by atomic force microscopy (AFM), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), spectroscopic ellipsometry, and water contact angle (WCA) measurements. The GE/CS IL PEM coatings reveal higher wettability (WCA between 41 and 45°) and roughness (root mean square, Rq, values between 74.5 and 89.1 nm) than the unmodified PET (WCA of 90.9° and surface roughness of 26.9 nm). The PEMs are homogeneous surface coatings with durability after exposure to phosphate-buffered saline (pH 7.4) for 24 h. The ILs impart low minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). The MIC and MBC are lower than 0.625 μg/mL against P. aeruginosa. The CS and GE and the GE/CS PEM do not provide any antimicrobial effect. However, the GE/CS IL PEMs show high antimicrobial capacity, preventing the attachment and growth of microbial cells. The GE/CS IL PEMs are durable, bactericidal, and anti-adhesive surfaces for PET.
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•Poly(ethylene terephthalate) is associated with polyelectrolyte multilayers.•Ionic liquids are associated with the polyelectrolyte multilayers by layer-by-layer.•The ionic liquids increase the surface roughness of the surface coatings.•The surface coatings are stable in buffer solutions (pH 5.0 and 7.4) at 37 °C.•The ionic liquids support outstanding antimicrobial surface coatings.
Aromatic hydrocarbons are extensive environmental pollutants occurring in both water and air media, and their removal is a priority effort for a healthy environment. The use of adsorbents is among ...the several strategies used for the remediation of these compounds. In this paper, we aim the synthesis of an amphiphilic hydrogel with the potential for the simultaneous sorption of a set of monocyclic and polycyclic aromatic hydrocarbons associated with toxicity effects in humans. Thus, we start by the synthesis of a copolymer-based in chitosan and β-cyclodextrin previously functionalized with the maleic anhydride. The presence of β-cyclodextrin will confer the ability to interact with hydrophobic compounds. The resulting material is posteriorly incorporated in a cryogel of poly(vinyl alcohol) matrix. We aim to improve the amphiphilic ability of the hydrogel matrix. The obtained hydrogel was characterized by swelling water kinetics, thermogravimetric analysis, rheological measurements, and scanning electron microscopy. The sorption of aromatic hydrocarbons onto the gel is characterized by pseudo-first-order kinetics and Henry isotherm, suggesting a physisorption mechanism. The results show that the presence of maleic anhydride-β-cyclodextrin and chitosan into hydrogels leads to an increase in the removal efficiency of the aromatic compounds. Additionally, the capacity of this hydrogel for removing these pollutants from a fossil fuel sample has also been tested.
Strategies for incorporating water-insoluble photosensitisers (PS) in drug delivery systems have been extensively studied. In this work, we evaluate the formation, characterisation, drug sorption ...studies, and cytotoxicity of chitosan (CHT)/chondroitin sulphate (CS) polyelectrolyte complexes (PECs) coated with polystyrene-block-poly(acrylic acid) (PS-b-PAA) nanoparticles (NPs) loaded with chloroaluminum phthalocyanine (AlClPc). The PECs were characterised by infrared spectroscopy (FTIR), differential scanning calorimetric (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The PS-b-PAA NPs on the PEC surface was confirmed by scanning electron microscopy (SEM). Additionally, optical images distinguished the PEC structures containing PS-b-PAA or PS-b-PAA/AlClPc from the unloaded PEC. Kinetic and equilibrium studies investigate the sorption capacity of the PEC/PS-b-PAA toward AlClPc. The encapsulation efficiency reached 95% at 190 μg mL−1 AlClPc after only 15 min. The Brunauer-Emmett-Teller (BET) isotherm and pseudo-second-order kinetic fitted well to the experimental data. The PS-b-PAA NPs on the PEC surfaces increase the AlClPc bioavailability and the PEC structure stabilizes the PS-b-PAA/AlClPc nanostructures. The materials were cytocompatible upon healthy VERO (kidney epithelial cells), and cytotoxic against colorectal cancerous cells (HT-29 cells). For the first time, we associate PS-b-PAA/AlClPc with a hydrophilic and cytocompatible polysaccharide matrix. We suggest the use of these materials in strategies to treat cancer by using photodynamic therapy.
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•Polyelectrolyte complex (PECs) coacervates were created from polymer blends in an ionic liquid.•Polystyrene-block-poly(acrylic acid) nanoparticles were adsorbed on the PEC surfaces.•The polystyrene-block-poly(acrylic acid)/PEC pair was loaded with chloroaluminum phthalocyanine.•We suggest the use of these materials to treat cancer using photodynamic therapy.
We present chitosan (CHT)/heparin (HP) polyelectrolyte complexes (PECs) that quickly adsorb citrate-capped silver nanoparticles (AgNPs). CHT/HP blends in ionic liquid (HMImHSO4) form durable PECs ...after precipitation in water. CHT/HP PECs have positive Zeta potentials (higher than +20 mV). They adsorb citrate-capped AgNPs (Zeta potential of - 12.25 mV) synthesized from Turkevich's method. PEC/AgNPs composites are characterized by spectroscopic, thermal, and microscopy analyses. AgNPs on the PEC surfaces are confirmed by transmission electron microscopy. PECs adsorb AgNPs from aqueous suspensions, achieving ≈ 95% of removal (17.18 μg of AgNPs per milligram of PEC) after only 10 min. The pseudo-second-order kinetic model adjusted well to the experimental data. The PECs release approximately 11.80 μg/mg Ag+ (66%) compared to the initial adsorbed AgNPs content (17.18 μg/mg) after 7200 min at pH 2.0. The PECs present low swelling degrees (between 130 and 150%), supporting high stability in water. PEC/AgNPs composites promote significant bactericidal activity toward Staphylococcus aureus and Escherichia coli between 0.25 and 0.5 mg/mL. This study shows a new strategy to create hybrid polysaccharide/AgNPs composites. PECs can stabilize the AgNPs and release Ag+ ions, supporting antimicrobial materials.
•Polyelectrolyte complexes (PECs) were synthesized using a green solvent.•95% of the citrate-capped silver nanoparticles were adsorbed on PECs' surface.•Citrate-capped silver nanoparticles are visible on PECs.•Hybrid materials present low heparin release at simulated fluids.•The Citrate-capped silver nanoparticles sorption is faster than the Ag+ ion release.
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