Comparison of the adsorption of linear and cyclic antimicrobial peptides onto cellulosic compounds-reinforced poly(vinyl alcohol) films using QCM-D

Understanding peptide adsorption kinetics onto biomaterial surfaces is crucial for developing wound treatments. This study aims to explore the influence of cellulose acetate (CA) and cellulose nanocrystals (CNC) on peptide adsorption via quartz crystal microbalance with dissipation monitoring (QCM-D), using a cyclic peptide, Tiger 17, and a linear, Pexiganan. PVA was reinforced with 10 and 20% w/v of CA and CNC, spin-coated onto QCM-D sensors, and crosslinked with glutaraldehyde. Films containing higher percentages of cellulosic compounds promoted the highest peptide adsorption, with CNC-containing films being the most effective. While C80/20 PVA/CNC films achieved adsorption masses of ≈199 and ≈150 ng/cm2 for Tiger 17 and Pexiganan, respectively, the C80/20 PVA/CA films attained ≈168 and ≈122 ng/cm2 . The peptides’ structure also influenced adsorption, with Tiger 17 reaching greater frequency drops (ΔF) than Pexiganan. Sequential adsorption studies corroborated these findings. Even though the tendency was for PVA/CNC to promote the highest peptide binding, it was the PVA/CA films that reached the greatest peptide loading amount with the sequence Pexiganan + Tiger 17. Data are encouraging for developing new wound therapies reinforced with cellulosic compounds and modified with Tiger 17 and Pexiganan.Authors acknowledge the Portuguese Foundation for Science and Technology (FCT), Fulbright Scholarship Program, FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the Portuguese Government (OE) for funding the project with reference PTDC/CTM-TEX/28074/2017 (POCI-01–0145-FEDER028074). Authors also acknowledge project UID/CTM/00264/2020 of Centre for Textile Science and Technology (2C2T) on its components base (https://doi.org/10.54499/UIDB/00264/2020) and programmatic (https://doi.org/10.54499/UIDP/00264/2020). M.A.T., D.P.F and H.P. F. acknowledge FCT for PhD scholarship (SFRH/BD/148930/2019) and junior (CEECIND/02803/2017) and auxiliary researcher(2021.02720. CEECIND; https://doi.org/10.54499/DL57/2016/CP1377/CT0098) contracts, respectively

Thermo-mechanical performance of nanostructured electrospun composites produced from poly(vinyl alcohol) and cellulosic compounds for potential uses as wound dressings

The purpose of this research was to analyze the morphology, thermal and mechanical properties of poly(vinyl alcohol) (PVA)-based electrospun mats reinforced with cellulose acetate (CA) or cellulose nanocrystalline (CNC) for potential applications in wound dressings. Bead-free and water-stable electrospun nanofibers made of blends of PVA and CA or CNC were successfully produced and crosslinked with glutaraldehyde vapor. Crosslinking slightly increased the nanofibers’ diameters in order of 43 and 13% for 80/20 PVA/CA and PVA/CNC electrospun mats, respectively, while maintaining their bead-free morphology. Thermogravimetry (TGA) and differential scanning calorimetry (DSC) evaluations were employed to determine the miscibility and the thermal response of the uncrosslinked and crosslinked mats, reporting a reduction in mass loss upon addition of CA and CNC and upon crosslinking process. Polymers’ powder and mats (before and after crosslinking) crystallinity was assessed by X-ray diffraction analysis (XRD). Crosslinked mats experienced a slight reduction in crystallinity compared to the uncrosslinked. Static and dynamic tensile strength tests revealed that CA and CNC doped mats enhanced the Young's modulus and lowered deformation at failure compared to pristine PVA electrospun mats. Data from storage modulus (E’) demonstrated the strength of the physical interactions formed between PVA and the cellulosic derivatives (either before and after crosslinking), highlighting the stiffness of CA (231.58 MPa for the 80/20 mat) and, particularly, CNC (742.04 MPa for the 80/20 mat). This research uncovered important information concerning the chemical and physical relation between polymeric matrices and additives, essential for the proper selection of materials for wound dressings production.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 with reference PTDC/CTM-TEX/28074/2017 (POCI-01-0145-FEDER-028074). Authors also acknowledge project UIDP/00264/2020 of Centre for Textile Science and Technology (2C2T), funded by national funds through FCT/MCTES. M.A.T., D.P.F and H.P.F. also acknowledge FCT for PhD scholarship (SFRH/BD/148930/2019) and junior (CEECIND/02803/2017) and auxiliary researcher (2021.02720.CEECIND) contracts, respectively

Synthesis of Peptaibolin, an antimicrobial peptide

To tackle one of the biggest global health problems, the resistance of microorganisms to antibiotics, a collective effort in the search for more effective agents against bacteria was required. Peptides with antimicrobial activity have been raising much attention as a promising alternative for antibiotics. Peptaibols, for instance, are a family of antimicrobial peptides (AMPs) with great biomedical potential, in which the Peptaibolin can be highlighted. This peptide has gained relevance due to its small amino acids content, only four, and its acetyl group and a phenylalaninol residue (Phol) at the N-terminal and C-terminal, respectively. Here, we report the synthesis of Peptaibolin through Solid Phase Peptide Synthesis assisted by Microwave heating (MW-SPPS) in a pre-loaded Phe-Wang resin. Starting from a loading of 0.51 mmol/g, two syntheses were made, using two different combinations of coupling reagents. The best option was DIC/Oxima, achieving a yield of 50.0%. Proton Nuclear Magnetic Resonance (1H-NMR) studies confirmed the peptide structure, while High Performance Liquid Chromatography (HPLC) verified the peptide purity. The peptide solubility was examined against several combinations of solvents. Peptaibolin was not soluble in water, only in organic solvents or in the combination of both. Antimicrobial testing was conducted using Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. Minimum inhibitory concentration studies demonstrated the resistance of bacteria to the peptide action and the peptide instability in bacterial growth conditionsFundação para a Ciência e Tecnologia-FCT (Portugal) for funding through CQUM (UID/QUI/00686/2020) and project PTDC/QUI-COL/28052/2017. The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT. Authors also acknowledge FCT for funding the project PEPTEX with reference PTDC/CTM-TEX/28074/2017 (POCI-01-0145-FEDER-028074). They acknowledge project UID/CTM/00264/2021 of Centre for Textile Science and Technology (2C2T), funded by national funds through FCT/MCTE

Deri yara kaplamalarindaki uygulamalar için elektrik alan lif çekim ile üretilmiş Tiger 17 peptit yüklü polikaprolakton/selüloz asetat nano lifli matlar

A skin wound if not properly treated can result in a chronic wound susceptible to widespread infections, which can result in the patient's death. Currently, tissue engineering is described as an interdisciplinary field that combines principles of engineering, chemistry and biology to generate solutions that allow to repair, restore and/or improve the functions of injured tissues. In the same sense, the textile area addresses solutions based on polymeric fibers, produced from a wide range of polymers, which allow the generation of structures with a large surface area, porosity and mechanical resistance that can be used as bioactive dressings that promote a healing and efficient antimicrobial activity. This research work focused on the synthesis of Tiger 17, through microwave-assisted solid-phase synthesis methodologies, and Tiger 17 commercially obtained, respective structural characterization and evaluation of the antimicrobial capacity. Simultaneously, nanofibrous polymer matrices were produced using the electrospinning technique with the aim of immobilizing the developed biomolecule and thus creating potential vehicles for a local and sustainable antimicrobial action (controlled release). In order to verify its physical and chemical properties, advanced characterization techniques were used: proton nuclear magnetic resonance, high performance liquid chromatography, optical microscopy, scanning electron microscopy, fourier transform infrared spectroscopy–attenuated total reflectance, thermogravimetry, differential scanning calorimetry, contact angle and surface energy and determination of porosity and hydration.Düzgün tedavi edilmeyen bir cilt yarası, hastanın ölümüyle sonuçlanabilecek yaygın enfeksiyonlara duyarlı kronik bir yaraya neden olabilir. Günümüzde doku mühendisliği, hasarlı dokuların işlevlerini onarmaya, eski haline getirmeye ve/veya iyileştirmeye olanak tanıyan çözümler üretmek için mühendislik, kimya ve biyolojinin ilkelerini birleştiren disiplinler arası bir alan olarak tanımlanmaktadır. Bu kapsamda, tekstil, iyileşmeyi ve etkili antimikrobiyal aktiviteyi teşvik eden biyoaktif pansuman olarak kullanılabilecek, geniş yüzey alanlı, gözenekli ve mekanik dirençli yapıların oluşturulmasına izin veren, geniş bir polimer yelpazesinden üretilen liflere dayalı çözümler sunmaktadır. Bu araştırma çalışması, mikrodalga destekli katı faz sentez metodolojileri aracılığıyla Tiger 17'nin sentezine ve ticari olarak temin edilen Tiger 17 ile birlikte yapısal karakterizasyonunun ve antimikrobiyal kapasitenin değerlendirilmesine odaklanmıştır. Aynı zamanda, geliştirilen biyomolekülü hareketsiz hale getirmek ve böylece lokal ve sürdürülebilir bir antimikrobiyal etki (kontrollü salım) için potansiyel çözümler yaratmak amacıyla elektrik alan lif üretim tekniği kullanılarak nanolifli polimer matrisler üretildi. Yapının fiziksel ve kimyasal özelliklerini doğrulamak için, proton nükleer manyetik rezonans, yüksek performanslı sıvı kromatografisi, optik mikroskopi, taramalı elektron mikroskobu, fourier dönüşümü kızılötesi spektroskopisi-zayıflatılmış toplam yansıma, termogravimetri, diferansiyel taramalı kalorimetri, temas açısı, yüzey enerjisi, gözeneklilik ve su tutma ölçümleri gibi ileri karakterizasyon teknikleri kullanıldı

Sodium alginate/polycaprolactone co-axial wet-spun microfibers modified with N-carboxymethyl chitosan and the peptide AAPV for Staphylococcus aureus and human neutrophil elastase inhibition in potential chronic wound scenarios

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. Here, we proposed the incorporation of the peptide AAPV within an innovative co-axial drug delivery system, in which the peptide liberation was controlled by N-carboxymethyl chitosan (NCMC) solubilization, a pH-sensitive antimicrobial polymer effective against Staphylococcus aureus. The microfibers' core was composed of polycaprolactone (PCL), a mechanically resilient polymer, and AAPV, while the shell was made of the highly hydrated and absorbent sodium alginate (SA) and NCMC, responsive to neutral-basic pH (characteristic of CW). NCMC was loaded at twice its minimum bactericidal concentration (6.144 mg/mL) against S. aureus, while AAPV was loaded at its maximum inhibitory concentration against HNE (50 μg/mL), and the production of fibers with a core-shell structure, in which all components could be detected (directly or indirectly), was confirmed. Core-shell fibers were characterized as flexible and mechanically resilient, and structurally stable after 28-days of immersion in physiological-like environments. Time-kill kinetics evaluations revealed the effective action of NCMC against S. aureus, while elastase inhibitory activity examinations proved the ability of AAPV to reduce HNE levels. Cell biology testing confirmed the safety of the engineered fiber system for human tissue contact, with fibroblast-like cells and human keratinocytes maintaining their morphology while in contact with the produced fibers. Data confirmed the engineered drug delivery platform as potentially effective for applications in CW care.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 UIDP/00264/2020 of 2C2T and UID/QUI/00686/2020 of CQ, funded by national funds through FCT/MCTES. C.S.M. and H.P.F. also acknowledge FCT for PhD funding via scholarship 2020.08547.BD and for auxiliary researcher contract via 2021.02720.CEEIND, respectively

Study of the composition of coaxial microfibers with phase change materials under thermal analysis

Asphalt pavements cover a large area of urban centers and are directly related to Urban Heat Islands (UHI). These materials heat up by absorbing a large amount of solar energy and then slowly release it, generating environmental, economic and social impacts that directly harm the well-being of citizens. The use of Phase Change Materials (PCM) in asphalt mixtures is indicated in the literature as an efficient thermoregulation method to mitigate UHI. However, their direct incorporation in asphalt mixtures presents some disadvantages related to modifying the asphalt structure after PCM melting. The development of Coaxial Polymeric Fibers (CPF) emerges as an innovative alternative to incorporate PCM in asphalt mixtures. Thus, the research herein reported aims to produce and select the best composition of coaxial fibers composed of Polyethylene glycol (PEG) as PCM and core and cellulose acetate (Mn: 30,000 and 50,000) as sheath. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used for thermal characterization. TGA was used to analyse whether the materials could tolerate the mixing and compaction temperatures of the asphalt mixtures (up to about 200°C) without any mass loss, and DSC to assess the melting point for the CPF. Thereby it is possible to determine the effect of cellulose acetate molecular weight on the phase change temperature of PEG inside the CPF. This information will aid in deciding on suitable materials for asphalt concrete mixtures capable of withstanding asphalt mixing temperatures

Biomolecule-Based Biomaterials and Their Application in Drug Delivery Systems

The antibiotic crisis is a global concern [...

Emerging Antimicrobial and Immunomodulatory Fiber-Based Scaffolding Systems for Treating Diabetic Foot Ulcers

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. Considering these limitations and knowing of the urgent demand for new and more effective therapeutic systems for DFU care that will guarantee the quality of life for patients, research in this field has boomed in the last few years. In this review, the emerging innovations in DFU dressing systems via fiber-based scaffolds modified with bioactive compounds have been compiled; data focused on the innovations introduced in the last five years (2017–2022). A generalized overview of the classifications and constraints associated with DFUs healing and the bioactive agents, both antimicrobial and immunomodulatory, that can contribute actively to surpass such issues, has also been provided

Extraction of Cellulose-Based Polymers from Textile Wastes

The extraction and exploration of cellulose-based polymers is an exciting area of research [...

Special Issue “Antimicrobial Biomaterials: Recent Progress”

Biomaterials have demonstrated their ability to serve as effective drug delivery platforms, enabling targeted and localized administration of therapeutic agents [...