Biotechnological applications at GBMI: industry-driven "bio-research"

Peer Reviewe

Hydrogel dressings for advanced wound management

The published manuscript is available at EurekaSelect via http://www.eurekaselect.com/openurl/content.php?genre=article&doi=10.2174/0929867324666170920161246Composed in a large extent of water and due to their non-adhesiveness, hydrogels found their way to the wound dressing market as materials that provide a moisture environment for healing while being comfortable to the patient. Hydrogels’ exploitation is constantly increasing after evidences of their even broader therapeutic potential due to resemblance to dermal tissue and ability to induce partial skin regeneration. The innovation in advanced wound care is further directed to the development of so-called active dressings, where hydrogels are combined with components that enhance the primary purpose of providing a beneficial environment for wound healing. The aim of this mini-review is to concisely describe the relevance of hydrogel dressings as platforms for delivery of active molecules for improved management of difficult-to-treat wounds. The emphasis is on the most recent advances in development of stimuli-responsive hydrogels, which allow for control over wound healing efficiency in response to different external modalities. Novel strategies for monitoring of the wound status and healing progress based on incorporation of sensor molecules into the hydrogel platforms are also discussed.Peer ReviewedPostprint (author's final draft

Combined ultrasound-laccase assisted bleaching of cotton

This study evaluates the potential of using ultrasound to enhance the bleaching efficiency of laccase enzyme on cotton fabrics. Ultrasound of low intensity (7 W) and relatively short reaction time (30 min) seems to act in a synergistic way with the enzyme in the oxidation/removal of the natural colouring matter of cotton. The increased bleaching effect could be attributed to improved diffusion of the enzyme from the liquid phase to the fibres surface and throughout the textile structure. On the other hand inactivation of the laccase occurred increasing the intensity of the ultrasound. However, at the ultrasound power applied in the bleaching experiments the loss of enzyme activity was not significant enough to justify the use stabilizer such as polyvinyl alcohol. Furthermore, the polyvinyl alcohol appears to be a substrate for the laccase.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/8651/200

Strategies to prevent the occurrence of resistance against antibiotics by using advanced materials

This is a post-peer-review, pre-copyedit version of an article published in Applied microbiology and biotechnology The final authenticated version is available online at: http://dx.doi.org/10.1007/s00253-018-8776-0Drug resistance occurrence is a global healthcare concern responsible for the increased morbidity and mortality in hospitals, time of hospitalisation and huge financial loss. The failure of the most antibiotics to kill Bsuperbugs^ poses the urgent need to develop innovative strategies aimed at not only controlling bacterial infection but also the spread of resistance. The prevention of pathogen host invasion by inhibiting bacterial virulence and biofilm formation, and the utilisation of bactericidal agents with different mode of action than classic antibiotics are the two most promising new alternative strategies to overcome antibiotic resistance. Based on these novel approaches, researchers are developing different advanced materials (nanoparticles, hydrogels and surface coatings) with novel antimicrobial properties. In this review, we summarise the recent advances in terms of engineered materials to prevent bacteria-resistant infections according to the antimicrobial strategies underlying their design.Peer ReviewedPostprint (author's final draft

Simultaneous ultrasound-assisted hybrid polyzwitterion/antimicrobial peptide nanoparticles synthesis and deposition on silicone urinary catheters for prevention of biofilm-associated infections

Nosocomial infections caused by antibiotic-resistant bacteria are constantly growing healthcare threats, as they are the reason for the increased mortality, morbidity, and considerable financial burden due to the poor infection outcomes. Indwelling medical devices, such as urinary catheters, are frequently colonized by bacteria in the form of biofilms that cause dysfunction of the device and severe chronic infections. The current treatment strategies of such device-associated infections are impaired by the resistant pathogens but also by a risk of prompting the appearance of new antibiotic-resistant bacterial mechanisms. Herein, the one-step sonochemical synthesis of hybrid poly(sulfobetaine) methacrylate/Polymyxin B nanoparticles (pSBMA@PM NPs) coating was employed to engineer novel nanoenabled silicone catheters with improved antifouling, antibacterial, and antibiofilm efficiencies. The synergistic mode of action of nanohybridized zwitterionic polymer and antimicrobial peptide led to complete inhibition of the nonspecific protein adsorption and up to 97% reduction in Pseudomonas aeruginosa biofilm formation, in comparison with the pristine silicone. Additionally, the bactericidal activity in the hybrid coating reduced the free-floating and surface-attached bacterial growth by 8 logs, minimizing the probability for further P. aeruginosa spreading and host invasion. This coating was stable for up to 7 days under conditions simulating the real scenario of catheter usage and inhibited by 80% P. aeruginosa biofilms. For the same time of use, the pSBMA@PM NPs coating did not affect the metabolic activity and morphology of mammalian cells, demonstrating their capacity to control antibiotic-resistant biofilm-associated bacterial infections.Peer ReviewedPostprint (published version

Lipases to Improve the performance of formaldehyde-free durable press finished cotton fabrics

Lipases were used to restore partially the strength losses of cotton fabrics crosslinked with 1,2,3,4- utanetetracarboxylic acid. The enzymatic hydrolysis of the ester linkages at low temperature and neutral pH resulted in 10% strength recovery, coupled with a slight deterioration of the crease-resistance effect. The conventional alkaline hydrolysis provided higher strength recovery, however provoked considerable change in the durable press performance of the fabrics

Lignin-based nanoparticles as both structural and active elements in self-assembling and self-healing multifunctional hydrogels for chronic wound management

Efficient wound healing is feasible when the dressing materials simultaneously target multiple factors causing wound chronicity, such as deleterious proteolytic and oxidative enzymes and bacterial infection. Herein, entirely bio-based multifunctional self-assembled hydrogels for wound healing were developed by simply mixing two biopolymers, thiolated hyaluronic acid (HA-SH) and silk fibroin (SF), with lignin-based nanoparticles (NPs) as both structural and functional elements. Sono-enzymatic lignin modification with natural phenolic compounds results in antibacterial and antioxidant phenolated lignin nanoparticles (PLN) capable of establishing multiple interactions with both polymers. These strong and dynamic polymer-NP interactions endow the hydrogels with self-healing and shear-thinning properties, and pH-responsive NP release is triggered at neutral to alkaline pH (7–9). Despite being a physically crosslinked hydrogel, the material was stable for at least 7 days, and its mechanical and functional properties can be tuned depending on the polymer and NP concentration. Furthermore, human skin cells in contact with the nanocomposite hydrogels for 7 days showed more than 93% viability, while the viability of clinically relevant Staphylococcus aureus and Pseudomonas aeruginosa was reduced by 99.7 and 99.0%, respectively. The hydrogels inhibited up to 52% of the activity of myeloperoxidase and matrix metalloproteinases, responsible for wound chronicity, and showed a strong antioxidant effect, which are crucial features promoting wound healing.Peer ReviewedPostprint (published version

Immobilization of antimicrobial core-shell nanospheres onto silicone for prevention of Escherichia coli biofilm formation

Escherichia coli (E. coli) strains are among the most frequently isolated microorganisms in urinary tract infections able to colonize the surface of urinary catheters and form biofilms. These biofilms are highly resistant to antibiotics and host immune system, resulting in increased morbidity and mortality rates. Strategies to prevent biofilm development, especially via restricting the initial stages of bacteria attachment are therefore urgently needed. Herein, a common urinary catheter material – polydimethylsiloxane (PDMS) – was covalently functionalized with antibacterial aminocellulose nanospheres (ACNSs) using the epoxy/amine grafting chemistry. The PDMS surface was pre-activated with (3-glycidyloxypropyl)-triethoxysilane to introduce epoxy functionalities prior to immobilization of the intact ACNSs via its amino groups. The AC biopolymer was first sonochemically processed into NSs improving by up to 80% its potential to prevent the E. coli biofilm formation on a polystyrene surface. The silicone surface decorated with these NSs demonstrated efficient inhibition of E. coli biofilms, reducing the total biomass when compared with pristine silicone material. Therefore, the functionalization of silicone-based materials with ACNSs shows promise as potential platform for prevention of biofilm-associated infections caused by E. coli.Peer ReviewedPostprint (author's final draft

Sonochemical synthesis and stabilization of concentrated antimicrobial silver-chitosan nanoparticle dispersions

This work reports on a green synthetic route to produce concentrated aqueous dispersions of silver nanoparticles (AgNP) employing high-intensity ultrasound (US) and chitosan (CS) as a non-toxic reducing agent for Ag1 salts and AgNP stabilizer. The sonication simultaneously boosted the synthesis and improved the stability of the AgNP, capping them with CS. Hybrid AgNP-CS antimicrobial dispersions, stable for at least 6 months, were synthesized in a simple single step process. The use of US allowed for applying relatively mild processing temperatures (608C) and reaction time between 30 min and 3 h to obtain concentrated disper- sions of AgNP that otherwise could not be obtained even after 72 h under mechanical stirring at the same reaction conditions. Upon sonication spherical AgNP-CS with a size between 60 and 100 nm were generated, in contrast to the average diameter of 200 nm of the particles obtained by stirring. The antibacterial efficiency of the AgNP-CS hybrids was evaluated against the medically relevant pathogens Staphylococcus aureus and Escherichia coli. The US-synthesized AgNP-CS showed more than 3-fold higher antibacterial activity compared to the particles obtained under stirring, due to their higher concentration and smaller size.Postprint (author's final draft

Bio-preparation of cotton fabrics

This study attempted to introduce the bio-processes in the conventional scouring and bleaching preparation of cotton. The scouring with two types of pectinases, acting under acidic and alkaline conditions respectively, was as efficient as the chemical process in terms of obtained adequate water absorbency of the fabrics. The necessity of surfactants application in scouring was outlined. Bleaching of the fabrics was performed with hydrogen peroxide, which was enzymatically produced by glucose oxidase during oxidation of glucose. The aeration plays an important role in the enhancement of the enzyme reaction, so that the quantity of generated peroxide is sufficient to overcome the stabilizing effect of the glucose and protein in the subsequent bleaching. A closed-loop process reusing starch containing desizing baths in a single step scouring/bleaching operation with enzyme-generated peroxide was performed. (C) 2001 Elsevier Science Inc. All rights reserved