41 research outputs found
ANÁLISE DA EFICIÊNCIA DA REAÇÃO ENTRE COMPOSTOS DE COORDENAÇÃO E OS ÓXIDOS DE NITROGÊNIO (NOX) – MODELAGEM SINTÉTICA BIOINORGÂNICA COM VISTAS AMBIENTAL
Controlled release of cinnamon leaf oil from chitosan microcapsules embedded within a sodium alginate/gelatin hydrogel-like film for Pseudomonas aeruginosa elimination
Pseudomonas aeruginosa is considered a public threat, with antibiotics increasing their resistance. Essential oils (EOs) have demonstrated significant effects against microorganisms. However, due to their volatile nature, they cannot be used in their free-state. Here, hydrogel-like films were produced from a combination of sodium alginate (SA) and gelatin (GN) to serve as delivery platforms for the controlled release of cinnamon leaf oil (CLO) entrapped within chitosan (CS) microcapsules. The minimum inhibitory concentration (MIC) of CLO was established at 39.3 mg/mL against P. aeruginosa. CS microcapsules were prepared via ionotropic gelation with tripolyphosphate (TPP), encapsulating CLO at MIC. Successful production was confirmed by fluorescent microscopy using Nile red as a detection agent. Microcapsules were embedded within a biodegradable SA/GN polymeric matrix processed by solvent casting/phase inversion with SA/GN used at 70/30 polymer ratio at 2 wt.% SA concentration. A concentration of 2 wt.% CaCl2 was used as a coagulation bath. The CLO-containing CS microcapsules’ homogeneous distribution was guaranteed by successive vortex and blending processes applied prior to casting. CLO controlled release from the films was monitored in physiological pH for 24 h. Hydrated films were obtained, with the presence of loaded CS capsules being confirmed by FTIR. Qualitative/quantitative antimicrobial examinations validated the loaded film potential to fight P. aeruginosa.Authors acknowledge the Portuguese Foundation for Science and Technolog
Spun biotextiles in tissue engineering and biomolecules delivery systems
Nowadays, tissue engineering is described as an interdisciplinary field that combines engineering principles and life sciences to generate implantable devices to repair, restore and/or improve functions of injured tissues. Such devices are designed to induce the interaction and integration of tissue and cells within the implantable matrices and are manufactured to meet the appropriate physical, mechanical and physiological local demands. Biodegradable constructs based on polymeric fibers are desirable for tissue engineering due to their large surface area, interconnectivity, open pore structure, and controlled mechanical strength. Additionally, biodegradable constructs are also very sought-out for biomolecule delivery systems with a target-directed action. In the present review, we explore the properties of some of the most common biodegradable polymers used in tissue engineering applications and biomolecule delivery systems and highlight their most important uses.Authors acknowledge the Portuguese Foundation for Science and Technology (FCT),
FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the Portuguese
Government (OE) for funding the project PEPTEX with reference PTDC/CTM-TEX/28074/2017 (POCI-01-0145-
FEDER-028074). Authors also acknowledge project UID/CTM/00264/2020 of Centre for Textile Science and
Technology (2C2T), funded by national funds through FCT/MCTES
Nanoparticle synthesis and their integration into polymer-based fibers for biomedical applications
The potential of nanoparticles as effective drug delivery systems combined with the
versatility of fibers has led to the development of new and improved strategies to help in the
diagnosis and treatment of diseases. Nanoparticles have extraordinary characteristics that are helpful
in several applications, including wound dressings, microbial balance approaches, tissue regeneration,
and cancer treatment. Owing to their large surface area, tailor-ability, and persistent diameter, fibers
are also used for wound dressings, tissue engineering, controlled drug delivery, and protective
clothing. The combination of nanoparticles with fibers has the power to generate delivery systems
that have enhanced performance over the individual architectures. This review aims at illustrating the
main possibilities and trends of fibers functionalized with nanoparticles, focusing on inorganic and
organic nanoparticles and polymer-based fibers. Emphasis on the recent progress in the fabrication
procedures of several types of nanoparticles and in the description of the most used polymers to
produce fibers has been undertaken, along with the bioactivity of such alliances in several biomedical
applications. To finish, future perspectives of nanoparticles incorporated within polymer-based fibers
for clinical use are presented and discussed, thus showcasing relevant paths to follow for enhanced
success in the field.This research was funded by the Portuguese Foundation for Science and Technology (FCT) via
grants UIDP/00264/2020 of 2C2T Strategic Project 2020–2023 and project PTDC/CTMTEX/28074/2017.
This project has been funded by a Research Grant (2022) from the European Society of Clinical
Microbiology and Infectious Diseases (ESCMID) to J.C.A., J.M.D. and C.S.M. also acknowledge FCT
for PhD grants 2020.07387.BD and 2020.08547.BD, respectively, and H.P.F. for auxiliary researcher
contract 2021.02720.CEECIND
Modification of Ca2+-Crosslinked Sodium Alginate/Gelatin films with Propolis for an improved antimicrobial action
Problems associated with microbial resistance to antibiotics are growing due to their overuse.
In this scenario, plant extracts such as the propolis extract (PE) have been considered as potential
alternatives to antibiotics in the treatment of infected wounds, due to its antimicrobial properties
and ability to induce tissue regeneration. To improve the long-term effectiveness of PE in wound
healing, polymeric films composed of biodegradable and biocompatible polymers are being engineered
as delivery vehicles. Here, sodium alginate/gelatin (SA/GN) films containing PE were prepared
via a simple, green process of solvent casting/phase inversion technique, followed by crosslinking
with calcium chloride (CaCl2) solutions. The minimum inhibitory concentration (MIC) of PE
was established as 0.338 mg/mL for Staphylococcus aureus and 1.353 mg/mL for Pseudomonas aeruginosa,
the most prevalent bacteria in infected wounds. The PE was incorporated within the polymeric
films before (blended with the polymeric solution) and after (immobilization via physisorption)
their production. Flexible, highly hydrated SA/GN/PE films were obtained, and their antibacterial
activity was assessed via agar diffusion and killing time kinetics examinations. Data confirmed
the modified films effectiveness to fight bacterial infections caused by S. aureus and P. aeruginosa
and their ability to be applied in the treatment of infected wounds.Portuguese Foundation for Science and Technol-ogy (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI), and the Portuguese Government (OE) for funding the project PEPTEX with reference PTDC/CTM-TEX/28074/2017 (POCI-01-0145-FEDER-028074). The authors also acknowledge project UID/CTM/00264/2020 of Centre for Textile Science and Technology (2C2T), funded by national funds through FCT/MCTE
Antimicrobial action and clotting time of thin, hydrated poly(Vinyl Alcohol)/cellulose acetate films functionalized with LL37 for prospective wound-healing applications
Poly(vinyl alcohol)/cellulose acetate (PVA/CA) films were prepared via a new method that combines principles from solvent casting and phase inversion. To guarantee some degree of flexibility, films were produced with a higher percentage of PVA compared to CA, from 90/10 to 50/50. The antimicrobial peptide (AMP) LL37 was then anchored using dopamine as a binding agent. Films were characterized in terms of functional groups, thermal stability, tensile strength, porosity, swelling and degradation (stability in physiological media at different pHs). The antimicrobial performance of LL37 surface-modified films was tested against Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli in dynamic environment and in the presence and absence of an albumin interface. LL37 treated films demonstrated great antibacterial efficacy against the three kinds of bacteria, ≈ 75% inhibition for S. aureus, ≈ 85% for S. epidermidis and ≈ 60% for E. coli, regardless of PVA/CA ratio. Presence of albumin reduced bacteria inhibition in all tested groups, most likely due to the binding of the protein molecules to the antimicrobial agents, reducing the free fraction available for bacterial killing. Films treated with LL37 accelerated clotting time (≈ 10 min) above vancomycin and bare surfaces, demonstrating great capacity to activate the intrinsic coagulation cascade.Portuguese Foundation for Science and Technology (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the Portuguese Government (OE) for funding the project PEPTEX with reference POCI-01-0145-FEDER-028074. Authors also acknowledge project UID/CTM/00264/2019 of Centre for Textile Science and Technology (2C2T), funded by national funds through FCT/MCTE
Physical, thermal, and antibacterial effects of active essential oils with potential for biomedical applications loaded onto cellulose acetate/polycaprolactone wet-spun microfibers
New approaches to deal with the growing concern associated with antibiotic-resistant bacteria are emerging daily. Essential oils (EOs) are natural antimicrobial substances with great potential to mitigate this situation. However, their volatile nature, in their liquid-free form, has restricted their generalized application in biomedicine. Here, we propose the use of cellulose acetate (CA)/polycaprolactone (PCL) wet-spun fibers as potential delivery platforms of selected EOs to fight infections caused by Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Twenty EOs were selected and screened for their minimal inhibitory concentration (MIC), using the antibiotic ampicillin as positive control. The cinnamon leaf oil (CLO), cajeput oil (CJO), and the clove oil (CO) were the most effective EOs, against the Gram-positive (MIC < 22.38 mg/mL) and the Gram-negative (MIC < 11.19 mg/mL) bacteria. Uniform microfibers were successfully wet-spun from CA/PCL with an averaged diameter of 53.9 ± 4.5 µm, and then modified by immersion with CLO, CJO and CO at 2 × MIC value. EOs incorporation was confirmed by UV-visible spectroscopy, Fourier-transformed infrared spectroscopy, and thermal gravimetric analysis. However, while microfibers contained ampicillin at MIC (control) after the 72 h modification, the CLO, CO and CJO-loaded fibers registered ≈ 14%, 66%, and 76% of their MIC value, respectively. Data showed that even at small amounts the EO-modified microfibers were effective against the tested bacteria, both by killing bacteria more quickly or by disrupting more easily their cytoplasmic membrane than ampicillin. Considering the amount immobilized, CLO-modified fibers were deemed the most effective from the EOs group. These results indicate that CA/PCL microfibers loaded with EOs can be easily produced with increased antibacterial action, envisioning their use as scaffolding materials for the treatment of infections.Authors acknowledge the Portuguese Foundation for Science and Technology (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the Portuguese Government(OE) for funding the project PEPTEX with reference PTDC/CTM-TEX/28074/2017 (POCI-01-0145-FEDER-028074).Authors also acknowledge project UID/CTM/00264/2020 of Centre for Textile Science and Technology (2C2T),funded by national funds through FCT/MCTES. SEM studies were performed at the Materials CharacterizationServices of the University of Minho (SEMAT/UM)
Functionalization of crosslinked sodium alginate/gelatin wet-spun porous fibers with Nisin Z for the inhibition of Staphylococcus aureus-induced infections
Nisin Z, an amphipathic peptide, with a significant antibacterial activity against Gram-positive bacteria and low toxicity in humans, has been studied for food preservation applications. Thus far, very little research has been done to explore its potential in biomedicine. Here, we report the modification of sodium alginate (SA) and gelatin (GN) blended microfibers, produced via the wet-spinning technique, with Nisin Z, with the purpose of eradicating Staphylococcus aureus-induced infections. Wet-spun SAGN microfibers were successfully produced at a 70/30% v/v of SA (2 wt%)/GN (1 wt%) polymer ratio by extrusion within a calcium chloride (CaCl2) coagulation bath. Modifications to the biodegradable fibers’ chemical stability and structure were then introduced via crosslinking with CaCl2 and glutaraldehyde (SAGNCL). Regardless of the chemical modification employed, all microfibers were labelled as homogeneous both in size (≈246.79 µm) and shape (cylindrical and defect-free). SA-free microfibers, with an increased surface area for peptide immobilization, originated from the action of phosphate buffer saline solution on SAGN fibers, were also produced (GNCL). Their durability in physiological conditions (simulated body fluid) was, however, compromised very early in the experiment (day 1 and 3, with and without Nisin Z, respectively). Only the crosslinked SAGNCL fibers remained intact for the 28 day-testing period. Their thermal resilience in comparison with the unmodified and SA-free fibers was also demonstrated. Nisin Z was functionalized onto the unmodified and chemically altered fibers at an average concentration of 178 µg/mL. Nisin Z did not impact on the fiber’s morphology nor on their chemical/thermal stability. However, the peptide improved the SA fibers (control) structural integrity, guaranteeing its stability for longer, in physiological conditions. Its main effect was detected on the time-kill kinetics of the bacteria S. aureus. SAGNCL and GNCL loaded with Nisin Z were capable of progressively eliminating the bacteria, reaching an inhibition superior to 99% after 24 h of culture. The peptide-modified SA and SAGN were not as effective, losing their antimicrobial action after 6 h of incubation. Bacteria elimination was consistent with the release kinetics of Nisin Z from the fibers. In general, data revealed the increased potential and durable effect of Nisin Z (significantly superior to its free, unloaded form) against S. aureus-induced infections, while loaded onto prospective biomedical wet-spun scaffolds.This research received funding from the Portuguese Foundation for Science and Technology
(FCT) under the scope of the projects PTDC/CTM-TEX/28074/2017 (POCI-01-0145-FEDER-028074)
and UID/CTM/00264/2021
Combinatory action of chitosan-based blended films and loaded cajeput oil against Staphylococcus aureus and Pseudomonas aeruginosa-mediated infections
Chronic wounds (CW) have numerous entry ways for pathogen invasion and prosperity,
damaging host tissue and hindering tissue remodeling. Essential oils exert quick and efficient antimicrobial
(AM) action, unlikely to induce bacterial resistance. Cajeput oil (CJO) has strong AM
properties, namely against Staphylococcus aureus and Pseudomonas aeruginosa. Chitosan (CS) is a natural
and biodegradable cationic polysaccharide, also widely known for its AM features. CS and
poly(vinyl alcohol) (PVA) films were prepared (ratio 30/70; 9 wt%) by solvent casting and phase
inversion method. Films’ thermal stability and chemical composition data reinforce polymer blending.
Films were supplemented with 1 and 10 wt% of CJO in relation to total polymeric mass. Loaded
films were 23 and 57% thicker, respectively, than the unloaded films. Degree of swelling and porosity
also increased, particularly with 10 wt% CJO. AM testing revealed that CS films alone were effective
against both bacteria, eradicating all P. aeruginosa within the hour (*** p < 0.001). Still, loaded
CS/PVA films showed improved AM traits, being significantly more efficient than unloaded films
right after 2 h of contact. This study is the first proof of concept that CJO can be dispersed into
CS/PVA films and show bactericidal effects, particularly against P. aeruginosa, this way opening new
avenues for CW therapeutics.Authors acknowledge the Portuguese Foundation for Science and Technology
(FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI)
and the Portuguese Government (OE) for funding the project PEPTEX with reference PTDC/CTMTEX/28074/2017 (POCI-01-0145-FEDER-028074). Authors also acknowledge project
UID/CTM/00264/2020 of Centre for Textile Science and Technology (2C2T), funded by national
funds through FCT/MCTES