Publications by authors named "Helena P Felgueiras"

Immobilization of peptides onto nanofiber dressings holds significant potential for chronic wound treatment. However, it is necessary to understand the adsorptive capacity of the produced substrates and the binding affinity of the peptides to determine the interface success. This study aims at exploring for the first time the influence of electrospun poly(vinyl alcohol)-based nanofibers on the adsorption of a cyclic peptide, Tiger 17, and of a linear peptide, Pexiganan, using quartz crystal microbalance with dissipation monitoring (QCM-D).

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Chronic wounds represent a serious worldwide concern, being often associated with bacterial infections. As the prevalence of bacterial infections increase, it is crucial to search for alternatives. Essential oils (EOs) constitute a promising option to antibiotics due to their strong anti-inflammatory, analgesic, antioxidant and antibacterial properties.

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Article Synopsis
  • Diabetic ulcers are challenging to heal due to increased human neutrophil elastase (HNE) secretion and bacterial infections. The study focused on creating electrospun fibers from polycaprolactone (PCL) and polyethylene glycol (PEG) that contain elastase-targeting peptides (AAPV and WAAPV).
  • Characterization showed that WAAPV effectively inhibits HNE, and the addition of PEG helps control fiber degradation and allows for sustained peptide release over 24 hours.
  • The peptide-loaded fibers demonstrated significant antibacterial effects against certain bacteria, inhibiting growth by up to 78%, offering promising strategies for treating diabetic ulcers.
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Biomaterials have demonstrated their ability to serve as effective drug delivery platforms, enabling targeted and localized administration of therapeutic agents [...

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Microbial colonization and development of infections in wounds is a sign of chronicity. The prevailing approach to manage and treat these wounds involves dressings. However, these often fail in effectively addressing infections, as they struggle to both absorb exudates and maintain optimal local moisture.

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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.

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Green Antimicrobials.

Antibiotics (Basel)

June 2023

In the last couple of years, the awareness of climate change and high pollution levels have raised our sense of ecological responsibility [...

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In chronic wound (CW) scenarios, Staphylococcus aureus-induced infections are very prevalent. This leads to abnormal inflammatory processes, in which proteolytic enzymes, such as human neutrophil elastase (HNE), become highly expressed. Alanine-Alanine-Proline-Valine (AAPV) is an antimicrobial tetrapeptide capable of suppressing the HNE activity, restoring its expression to standard rates.

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Diabetic foot ulcers (DFUs) are one of the main complications of diabetes and are characterized by their complexity and severity, which are frequently aggravated by overexpressed inflammatory factors and polymicrobial infections. Most dressing systems offer a passive action in the treatment of DFUs, being frequently combined with antibiotic or immunomodulatory therapies. However, in many instances due to these combined therapies' inability to properly fight microbial presence, and provide a suitable, breathable and moist environment that is also capable of protecting the site from secondary microbial invasions or further harm, aggravation of the wound state is unavoidable and lower limb amputations are necessary.

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The brown macroalgae of the species has reached European waters and the Strait of Gibraltar as an invasive species. The proliferation and colonization of the species in subtidal and intertidal zones of these regions imposes significant threats to local ecosystems and additionally represents a significant socioeconomic burden related to the large amounts of biomass accumulated as waste. As a way to minimize the effects caused by the accumulation of algae biomass, investigations have been made to employ this biomass as a raw material in value-added products or technologies.

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Biomaterials can be used as implantable devices or drug delivery platforms, which have significant impacts on the patient's quality of life [...

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Article Synopsis
  • - Infection is a significant challenge in managing chronic wounds, and while various dressings exist, there is no ideal solution that combines antimicrobial properties, compatibility with cells, and healing promotion.
  • - Researchers created polyvinyl alcohol (PVA) nanofibrous mats reinforced with cellulose nanocrystal (CNC) and specialized peptides to enhance their properties; the mats showed improved surface energy and structural stability despite a decrease in mechanical strength due to CNC incorporation.
  • - The study found that peptide-doped mats effectively fought bacteria like Staphylococcus aureus and Pseudomonas aeruginosa, with one peptide, pexiganan, being particularly effective; the 90/10 PVA/CNC mats emerged as the best
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The extraction and exploration of cellulose-based polymers is an exciting area of research [...

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In this research, we propose to engineer a nanostructured mat that can simultaneously kill bacteria and promote an environment conducive to healing for prospective wound care. Polyvinyl alcohol (PVA) and cellulose acetate (CA) were combined at different polymer ratios (100/0, 90/10, 80/20% v/v), electrospun and crosslinked with glutaraldehyde vapor. Crosslinked fibers increased in diameter (from 194 to 278 nm), retaining their uniform structure.

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Almost two years have passed since COVID-19 was officially declared a pandemic by the World Health Organization. However, it still holds a tight grasp on the entire human population. Several variants of concern, one after another, have spread throughout the world.

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Antimicrobial textiles are helpful tools to fight against multidrug-resistant pathogens and nosocomial infections. The deposition of silver nanoparticles (AgNPs) onto textiles has been studied to achieve antimicrobial properties. Yet, due to health and environmental safety concerns associated with such formulations, processing optimizations have been introduced: biocompatible materials, environmentally friendly agents, and delivery platforms that ensure a controlled release.

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New approaches to deal with the growing concern associated with antibiotic-resistant bacteria are in high demand [...

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Article Synopsis
  • - The study aims to enhance face masks by incorporating antiviral essential oils (EOs) into electrospun fibrous mats made of polycaprolactone (PCL), which can actively affect the viability of viruses like SARS-CoV-2.
  • - Three effective EOs—lemongrass, Niaouli, and eucalyptus—were identified and tested, showing significant virucidal concentrations against the MS2 virus, a potential analog for SARS-CoV-2.
  • - The modified mats demonstrated superhydrophobic properties, good mechanical resilience, and effective virus retention, making them potentially superior protective elements in masks compared to traditional options.
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Electrospinning and wet-spinning have been recognized as two of the most efficient and promising techniques for producing polymeric fibrous constructs for a wide range of applications, including optics, electronics, food industry and biomedical applications. They have gained considerable attention in the past few decades because of their unique features and tunable architectures that can mimic desirable biological features, responding more effectively to local demands. In this review, various fiber architectures and configurations, varying from monolayer and core-shell fibers to tri-axial, porous, multilayer, side-by-side and helical fibers, are discussed, highlighting the influence of processing parameters in the final constructs.

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Inflammatory bowel disease (IBD) is a group of disabling, destructive and incurable immune-mediated inflammatory diseases comprising Crohn's disease (CD) and ulcerative colitis (UC), disorders that are highly prevalent worldwide and demand a large investment in healthcare. A persistent inflammatory state enables the dysfunction and destruction of healthy tissue, hindering the initiation and endurance of wound healing. Current treatments are ineffective at counteracting disease progression.

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In assigning priorities, skin infectious diseases are frequently classified as minor when compared to infectious diseases of high mortality rates, such as tuberculosis or HIV. However, skin infections are amongst the most common and prevalent diseases worldwide. Elderly individuals present an increased susceptibility to skin infections, which may develop atypical signs and symptoms or even complicate pre-existing chronic disorders.

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Marine-derived chitosan (CS) is a cationic polysaccharide widely studied for its bioactivity, which is mostly attached to its primary amine groups. CS is able to neutralize reactive oxygen species (ROS) from the microenvironments in which it is integrated, consequently reducing cell-induced oxidative stress. It also acts as a bacterial peripheral layer hindering nutrient intake and interacting with negatively charged outer cellular components, which lead to an increase in the cell permeability or to its lysis.

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In the last decades, much research has been done to fasten wound healing and target-direct drug delivery. Hydrogel-based scaffolds have been a recurrent solution in both cases, with some reaching already the market, even though their mechanical stability remains a challenge. To overcome this limitation, reinforcement of hydrogels with fibers has been explored.

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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 -induced infections.

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