Antimicrobial Composites Based on Methacrylic Acid-Methyl Methacrylate Electrospun Fibers Stabilized with Copper(II).

This study presents fibers based on methacrylic acid-methyl methacrylate (Eudragit L100) as Cu(II) adsorbents, resulting in antimicrobial complexes. Eudragit L100, an anionic copolymer synthesized by radical polymerization, was electrospun in dimethylformamide (DMF) and ethanol (EtOH). The electrospinning process was optimized through a 22-factorial design, with independent variables (copolymer concentration and EtOH/DMF volume ratio) and three repetitions at the central point. The smallest average fiber diameter (259 ± 53 nm) was obtained at 14% w/v Eudragit L100 and 80/20 EtOH/DMF volume ratio. The fibers were characterized using scanning electron microscopy (SEM), infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), and differential scanning calorimetry (DSC). The pseudo-second-order mechanism explained the kinetic adsorption toward Cu(II). The fibers exhibited a maximum adsorption capacity (qe) of 43.70 mg/g. The DSC analysis confirmed the Cu(II) absorption, indicating complexation between metallic ions and copolymer networks. The complexed fibers showed a lower degree of swelling than the non-complexed fibers. The complexed fibers exhibited bacteriostatic activity against Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. This study successfully optimized the electrospinning process to produce thin fibers based on Eudragit L100 for potential applications as adsorbents for Cu(II) ions in aqueous media and for controlling bacterial growth.

Bactericidal Pectin/Chitosan/Glycerol Films for Food Pack Coatings: A Critical Viewpoint.

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 (ε, %) of 19%. Washed films (WFs) had high tensile strength (σ > 46 MPa) and low elongation at break (ε, <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 Escherichia coli. The remaining HCl in the UF40 can be a disadvantage for food packaging applications; the UF40 (∅ = 8.5 mm; 55 µm thickness) releases H3O+/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.

Novel poly(ε-caprolactone)/amino-functionalized tannin electrospun membranes as scaffolds for tissue engineering.

Poly(ε-caprolactone) (PCL) is a hydrophobic and cytocompatible aliphatic polyester that has been used to produce PCL-based nanofibrous for both wound healing and tissue repair. However, the high hydrophobicity and low water adsorptive have been challenges for developing PCL-based materials for use in tissue engineering field. Here, we report a new polymer (a hydrophilic amino-functionalized tannin (TN)) that is associated with PCL for developing PCL-TN blends at different PCL:TN weight ratios (100:0, 95:5, 85:15 and 78:22). PCL:TN ratio may be tuned to modulate hydrophilicity and cytocompatibility of the nanofibers. The neutralization step and surface wettability played an important role in the attachment of human adipose-derived stem cells (ADSC cells) on PCL-TN membranes. Also, fluorescence images confirmed great proliferation of ADSC cells on the PCL-TN electrospun surfaces. Yet, neutralized PCL-TN nanofibers promoted bactericidal activity against Pseudomonas aeruginosa. These membranes have potential to be used as scaffolds for tissue engineering purposes.

Preparation and cytotoxicity of N-modified chitosan nanoparticles applied in curcumin delivery.

Nanoparticles (NPs) based on N,N-dimethyl chitosan (DMC) and N,N,N-trimethyl chitosan (TMC), physical crosslinked with sodium tripolyphosphate (TPP) were successful obtained, using water/benzyl alcohol emulsion system. NPs morphologies were evaluated by Scanning Electron Microscopy and Transmission Electron Microscopy. NPs were characterized by Infrared Spectroscopy (FTIR), Thermogravimetric Analysis, Zeta Potential, Differential Scanning Calorimetry and Wide-angle X-ray Scattering. Curcumin (CUR) was loaded onto NPs and controlled release studies were evaluated in simulated intestinal fluid and in simulated gastric fluid. Cytotoxicity assays showed only loaded TMC/TPP particles containing CUR were slightly cytotoxic on human cervical tumor cells (SiHa cells), concerning unloaded TMC/TPP particles. Conversely, loaded NPs (TMC/TPP/CUR and DMC/TPP/CUR), especially TMC/TPP/CUR sample presented greater biocompatibility toward healthy VERO cells than unloaded NPs (TMC/TPP and DMC/TPP).

Shielding effect of 'surface ion pairs' on physicochemical and bactericidal properties of N,N,N-trimethyl chitosan salts.

Different methodologies were employed in this study to synthesize N,N,N-trimethyl chitosan salts (TMC). TMC free of O-methylation and with partial O-methylation were obtained and characterized through 1H nuclear magnetic resonance, wide angle X-ray scattering, scanning electron microscopy coupled with X-ray energy dispersive spectroscopy, and thermogravimetric analysis. It was verified that the dialysis process allowed the removal of 'surface ion pairs' on TMC salt structure, increasing the mobility of TMC chains. The surface ion pairs considerably increased the material crystallinity, this property being independent of the used synthesis methodology. Biological tests showed that after dialysis, TMC salts free of 'surface ion pairs' kill Escherichia coli in only 6h of incubation. So, the increase in the mobility of dialyzed TMC chains allowed a strong interaction with the cell envelope and the good bactericidal activity of TMC was enhanced.

Synthesis and characterization of pectin derivative with antitumor property against Caco-2 colon cancer cells.

New pectin derivative (Pec-MA) was obtained in specific reaction conditions. The presence of maleoyl groups in Pec-MA structure was confirmed by (1)H NMR and FTIR spectroscopy. The substitution degree of Pec-MA (DS=24%) was determined by (1)H NMR. The properties of Pec-MA were investigated through WAXS, TGA/DTG, SEM and zeta potential techniques. The Pec-MA presented amorphous characteristics and higher-thermal stability compared to raw pectin (Pec). In addition, considerable morphological differences between Pec-MA and Pec were observed by SEM. The cytotoxic effect on the Caco-2 cells showed that the Pec-MA significantly inhibited the growth of colon cancer cells whereas the Pec-MA does not show any cytotoxic effect on the VERO healthy cells. This result opens new perspectives for the manufacture of biomaterials based on Pec with anti-tumor properties.

Preparation and cytotoxicity of N,N,N-trimethyl chitosan/alginate beads containing gold nanoparticles.

Polyelectrolyte complex beads based on N,N,N-trimethyl chitosan (TMC) and sodium alginate (ALG) were obtained. This biomaterial was characterised by FTIR, TGA/DTG, DSC and SEM analysis. The good properties of polyelectrolyte complex hydrogel beads were associated, for the first time, with gold nanoparticles (AuNPs). Through a straightforward methodology, AuNPs were encapsulated into the beads. The in vitro cytotoxicity assays on the Caco-2 colon cancer cells and healthy VERO cells showed that the beads presented good biocompatibility on both cell lines, whereas the beads loaded with gold nanoparticles (beads/AuNPs) was slightly cytotoxic on the Caco-2 and VERO cells.

Antimicrobial activity of chitosan derivatives containing N-quaternized moieties in its backbone: a review.

Chitosan, which is derived from a deacetylation reaction of chitin, has attractive antimicrobial activity. However, chitosan applications as a biocide are only effective in acidic medium due to its low solubility in neutral and basic conditions. Also, the positive charges carried by the protonated amine groups of chitosan (in acidic conditions) that are the driving force for its solubilization are also associated with its antimicrobial activity. Therefore, chemical modifications of chitosan are required to enhance its solubility and broaden the spectrum of its applications, including as biocide. Quaternization on the nitrogen atom of chitosan is the most used route to render water-soluble chitosan-derivatives, especially at physiological pH conditions. Recent reports in the literature demonstrate that such chitosan-derivatives present excellent antimicrobial activity due to permanent positive charge on nitrogen atoms side-bonded to the polymer backbone. This review presents some relevant work regarding the use of quaternized chitosan-derivatives obtained by different synthetic paths in applications as antimicrobial agents.