Multifunctional enzymatically generated hydrogels for chronic wound application

The healing of chronic wounds requires intensive medical intervention at huge healthcare costs. Dressing materials should consider the multifactorial nature of these wounds comprising deleterious proteolytic and oxidative enzymes and high bacterial load. In this work, multifunctional hydrogels for chronic wound application were produced by enzymatic cross- linking of thiolated chitosan and gallic acid. The hydrogels combine several beneficial to wound healing properties, controlling the matrix metalloproteinases (MMPs) and myeloperoxidase (MPO) activities, oxidative stress, and bacterial contamination. In vitro studies revealed above 90% antioxidant activity, and MPO and collagenase inhibition by up to 98 and 23%, respectively. Ex vivo studies with venous leg ulcer exudates confirmed the inhibitory capacity of the dressings against MPO and MMPs. Additionally, the hydrogels reduced the population of the most frequently encountered in nonhealing wounds bacterial strains. The stable at physiological conditions and resistant to lysozyme degradation hydrogels showed high biocompatibility with human skin fibroblastsPeer ReviewedPostprint (author's final draft

Rapid Colorimetric Detection of Wound Infection with a Fluidic Paper Device

Chronic wounds; Infection biomarker; Myeloperoxidase; ColorimetryFerides i lesions; Biomarcadors d'infecció; Mieloperoxidasa; ColorimetriaHeridas crónicas; Biomarcador de infección; Mieloperoxidasa; ColorimetríaCurrent procedures for the assessment of chronic wound infection are time-consuming and require complex instruments and trained personnel. The incidence of chronic wounds worldwide, and the associated economic burden, urge for simple and cheap point-of-care testing (PoCT) devices for fast on-site diagnosis to enable appropriate early treatment. The enzyme myeloperoxidase (MPO), whose activity in infected wounds is about ten times higher than in non-infected wounds, appears to be a suitable biomarker for wound infection diagnosis. Herein, we develop a single-component foldable paper-based device for the detection of MPO in wound fluids. The analyte detection is achieved in two steps: (i) selective immunocapture of MPO, and (ii) reaction of a specific dye with the captured MPO, yielding a purple color with increasing intensity as a function of the MPO activity in infected wounds in the range of 20-85 U/mL. Ex vivo experiments with wound fluids validated the analytic efficiency of the paper-based device, and the results strongly correlate with a spectrophotometric assay

New myeloperoxidase detection system based on enzyme-catalysed oxidative synthesis of a dye for paper-based diagnostic devices

The severity and cost of wound infections strongly demands for simple and fast methods for wound infection determination. Point-of-care testing devices play a crucial role in order to achieve a fast diagnosis and early treatment. Myeloperoxidase (MPO) enzyme, detected in fluids of infected wounds has been postulated as a suitable biomarker for wound diagnostics. Here we present a new system for MPO detection, based on enzyme-catalysed oxidative synthesis of a dye that can be incorporated into paper-based point of care devices. Visual MPO detection has been achieved through the use of phenylenediamine, a common colourless hair dye precursor. MPO oxidation of these compounds yielded bright coloured products distinguishable from the colour of the wound environment. Immobilisation of the MPO substrates on paper strips was achieved through in situ interaction of the oxidised coloured product with branched polyethyleneimine. The colour reaction of the immobilized substrates, detectable by naked eye, responds to the MPO levels present in infected wound fluids revealing an easy system for incorporation of MPO detection in paper based diagnostic devices.Peer ReviewedPostprint (author's final draft

Rapid colorimetric detection of wound infection with a fluidic paper device

Current procedures for the assessment of chronic wound infection are time-consuming and require complex instruments and trained personnel. The incidence of chronic wounds worldwide, and the associated economic burden, urge for simple and cheap point-of-care testing (PoCT) devices for fast on-site diagnosis to enable appropriate early treatment. The enzyme myeloperoxidase (MPO), whose activity in infected wounds is about ten times higher than in non-infected wounds, appears to be a suitable biomarker for wound infection diagnosis. Herein, we develop a single-component foldable paper-based device for the detection of MPO in wound fluids. The analyte detection is achieved in two steps: (i) selective immunocapture of MPO, and (ii) reaction of a specific dye with the captured MPO, yielding a purple color with increasing intensity as a function of the MPO activity in infected wounds in the range of 20–85 U/mL. Ex vivo experiments with wound fluids validated the analytic efficiency of the paper-based device, and the results strongly correlate with a spectrophotometric assay.Peer ReviewedPostprint (published version

Conocimiento de los profesionales de urgencias sobre la prevención y tratamiento de las úlceras por presión Professional's knowledge of the department of urgencies on the prevention and treatment of pressure ulcers

Introducción: muy frecuentemente en el medio de las urgencias hospitalarias suele infravalorarse la frecuencia, la repercusión personal, social e incluso económica, tanto de las úlceras por presión (UPP) como de otras heridas crónicas. Las situaciones críticas precisan de una urgente atención y obligan a establecer prioridades como la estabilidad del paciente agudo, anteponiéndose a otras situaciones de menor relevancia. Pero la necesidad de abordar una "urgencia" no puede desmerecer o anular el abordaje de otras situaciones no críticas, que pueden influir notablemente en el paciente y en su estado de salud. Partiendo de estos criterios, podríamos formularnos algunas preguntas: • ¿Está el personal de urgencias "formado" para abordar correctamente las UPP y otras heridas crónicas? • ¿Se aplican las estrategias adecuadas de prevención y tratamiento dentro de los servicios de urgencias? Objetivo: analizar los conocimientos de los profesionales de urgencias, con responsabilidad en el cuidado de los pacientes: equipo de enfermería (diplomado y auxiliar), equipo médico (adjunto y residente) y equipo sanitario; sobre la prevención y el tratamiento de las UPP, siguiendo las recomendaciones del Grupo Nacional para el Estudio y Asesoramiento de úlceras por Presión y Heridas Crónica (GNEAUPP). Método: estudio descriptivo mediante encuesta autocumplimentada: 33 preguntas con respuesta dicotómica: Sí/NO. Población de estudio (n) = 90 profesionales del servicio de urgencias. Resultados y conclusiones: se obtuvo una elevada tasa de respuesta, 97,7%. A pesar de que el 79% de los profesionales consideraban no poseer una adecuada formación resultaron tener un "acierto global" del 73% en las cuestiones sobre prevención y un 69% en las referentes al tratamiento. Aunque los resultados denotan ser favorables de forma generalizada, existen importantes "cuestiones particulares" de cada ámbito (tratamiento y prevención) relacionadas con la categoría profesional y el índice de fallo.Introduction: very frequently in the way of the hospitable urgencies there is in the habit of being underestimated the frequency, the personal, social and even economic repercussion, so much of the pressure ulcers, as of other chronic wounds. The critical situations are necessary an urgent attention and force to establish priorities as the stability of the critical patient, being in front of other situations of minor relevancy. But the need to approach a hospitable urgency, cannot be unworthy or annul the boarding of other not critical situations, which can influence notably in the patient and his condition of health. Departing from these criteria, it might formulate some questions: • Are the personnel of urgencies "formed" to correctly approach pressure ulcers and other chronic wounds? • Are applied the suitable strategies for prevention and treatment in the department of urgencies? Objective: to analyse the knowledge of the professionals of the department of urgencies, with responsibility in the care of the patients: the nurse teams (nurses and nurse assistants), medical equipment (head and resident) and sanitary team; for the prevention and the treatment of pressure ulcers, following the recommendations of the GNEAUPP. Method: descriptive study by auto-completed test: 33 questions with dichotomy answer: YES/NO. Population of study (n) = 90 professionals of the department of urgencies. Results and conclusions: was obtained a high rate of answer, 97,7%. In spite of the fact, that 79% of the professionals was considering themselves, not to possess a suitable formation. They proved to have a "global success" of 73% in the questions on prevention and 69% in the relating ones to the treatment. Though the results denote to be favourable of widespread form, there exist important "particular questions" of every area (treatment and prevention) related to the professional category and the index of failure

Enzymatic synthesis of a thiolated chitosan-based wound dressing crosslinked with chicoric acid

This work describes the enzymatic synthesis of multifunctional hydrogels for chronic wound treatment using thiolated chitosan and the natural polyphenol chicoric acid. Gelation was achieved by laccase-catalyzed oxidation of chicoric acid, a natural compound used for the first time as a homobifunctional crosslinker, reacting subsequently with nucleophilic thiol and amino groups from the chitosan derivative. This approach allowed for twice-faster gelation at three-fold reduced crosslinking reagent concentration, compared to reported enzymatic synthesis of hydrogels using gallic acid as a phenolic provider. Hydrogels with 600 % swelling capacity, coupled to only 20 % weight loss after 6 days in physiological conditions, were obtained. The clinically relevant gram-positive Staphylococcus aureus and the gram-negative Pseudomonas aeruginosa, were reduced by up to 4.5 and 5.5 logs, respectively. A tunable, in the range of 20 - 95 %, ex-vivo inhibition of myeloperoxidase (MPO) activity in chronic wound exudate was achieved, together with control over the total matrix metalloproteinases (MMPs) activities.Peer ReviewedPostprint (author's final draft

Enzymatic synthesis of a thiolated chitosan-based wound dressing crosslinked with chicoric acid

This work describes the enzymatic synthesis of multifunctional hydrogels for chronic wound treatment using thiolated chitosan and the natural polyphenol chicoric acid. Gelation was achieved by laccase-catalyzed oxidation of chicoric acid, a natural compound used for the first time as a homobifunctional crosslinker, reacting subsequently with nucleophilic thiol and amino groups from the chitosan derivative. This approach allowed for twice-faster gelation at three-fold reduced crosslinking reagent concentration, compared to reported enzymatic synthesis of hydrogels using gallic acid as a phenolic provider. Hydrogels with 600 % swelling capacity, coupled to only 20 % weight loss after 6 days in physiological conditions, were obtained. The clinically relevant gram-positive Staphylococcus aureus and the gram-negative Pseudomonas aeruginosa, were reduced by up to 4.5 and 5.5 logs, respectively. A tunable, in the range of 20 - 95 %, ex-vivo inhibition of myeloperoxidase (MPO) activity in chronic wound exudate was achieved, together with control over the total matrix metalloproteinases (MMPs) activities.Peer Reviewe

Poly(sulfobetaine methacrylate)/poly(ethylene glycole) hydrogels for chronic wounds management

Polyzwitterions (PZI) recently emerged as biomaterials with excellent bio- and haemo-compatibility, demonstrating lower protein adsorption on their surfaces even compared to the golden standard in the field – poly(ethylene glycol) (PEG). Although PZI combine many beneficial for chronic wound treatment properties as nonfouling ability and high capacity to absorb wound exudate, their potential for such demanding application is still unrevealed. In this work, polysulfobetaine (PSB) networks were synthesized using PEG-based crosslinking agent, thus combining in one material two polymers with inherent antifouling properties. The obtained PSB hydrogels demonstrate linear temperature dependence of their swelling capacity in water between 20 and 70 oC. Moreover, they all exhibit strong antipolyelelctrolyte behavior, increasing their swelling ratio between 10 and 22 times depending on their crosslinking degree as the NaCl concentration increased. The study also demonstrates the PSB high ability to bind water - ~40% bound water was determined for almost all PSB hydrogels, which is considered as the main reason for their ultra-low non-specific protein binding ability. Moreover, PZI networks effectively absorb and retain the major enzymes causing chronicity of the wounds as 30 to 40% myeloperoxidase (MPO) was loaded into the PSB hydrogels depending on their crosslinking degree. At the same time, PZI hydrogels do not inhibit neither MPO nor the collagenase activity, thus ensuring a decrease in their excessive amount in the chronic wounds but at the same not hampering the enzyme activity necessary for the proper wound healing. All PSB hydrogels demonstrated antibiofilm activity against S. aureus, a common bacterial representative in chronic wounds. The non-cytotoxicity and biocompatibility of the hydrogels were proved in vitro and in vivo. Thus, the study demonstrated the PSB hydrogels’ advantages as dressing materials for chronic wound healing, namely: i) high ability to absorb wound exudate; ii) high ability to bind water; iii) good control on the enzymes concentration in the chronic wounds through absorption iv) without inhibiting their activity; v) antibiofilm activity against common for the chronic wounds bacteria; vi) non-cytotoxicity and vii) in vivo proved very good tolerance by the surrounding tissues.Peer ReviewedPostprint (author's final draft

Poly(sulfobetaine methacrylate)/poly(ethylene glycole) hydrogels for chronic wounds management

Polyzwitterions (PZI) recently emerged as biomaterials with excellent bio- and haemo-compatibility, demonstrating lower protein adsorption on their surfaces even compared to the golden standard in the field – poly(ethylene glycol) (PEG). Although PZI combine many beneficial for chronic wound treatment properties as nonfouling ability and high capacity to absorb wound exudate, their potential for such demanding application is still unrevealed. In this work, polysulfobetaine (PSB) networks were synthesized using PEG-based crosslinking agent, thus combining in one material two polymers with inherent antifouling properties. The obtained PSB hydrogels demonstrate linear temperature dependence of their swelling capacity in water between 20 and 70 oC. Moreover, they all exhibit strong antipolyelelctrolyte behavior, increasing their swelling ratio between 10 and 22 times depending on their crosslinking degree as the NaCl concentration increased. The study also demonstrates the PSB high ability to bind water - ~40% bound water was determined for almost all PSB hydrogels, which is considered as the main reason for their ultra-low non-specific protein binding ability. Moreover, PZI networks effectively absorb and retain the major enzymes causing chronicity of the wounds as 30 to 40% myeloperoxidase (MPO) was loaded into the PSB hydrogels depending on their crosslinking degree. At the same time, PZI hydrogels do not inhibit neither MPO nor the collagenase activity, thus ensuring a decrease in their excessive amount in the chronic wounds but at the same not hampering the enzyme activity necessary for the proper wound healing. All PSB hydrogels demonstrated antibiofilm activity against S. aureus, a common bacterial representative in chronic wounds. The non-cytotoxicity and biocompatibility of the hydrogels were proved in vitro and in vivo. Thus, the study demonstrated the PSB hydrogels’ advantages as dressing materials for chronic wound healing, namely: i) high ability to absorb wound exudate; ii) high ability to bind water; iii) good control on the enzymes concentration in the chronic wounds through absorption iv) without inhibiting their activity; v) antibiofilm activity against common for the chronic wounds bacteria; vi) non-cytotoxicity and vii) in vivo proved very good tolerance by the surrounding tissues.Peer Reviewe

Antibiofilm poly(carboxybetaine methacrylate) hydrogels for chronic wounds dressings

The current study demonstrates the benefits of poly(carboxybetaine methacrylate) hydrogels in chronic wound healing. These hydrogels demonstrate high absorbing capacity upon swelling in salt solutions thus revealing great potential as dressings for highly exuding chronic wounds. Moreover, upon swelling they expand, increasing their volume by 25%, which makes them patient friendly ensuring also the proper wound healing. Poly(carboxybetaine methacrylate) hydrogels were also shown to absorb collagenase and myeloperoxidase, two enzymes that are specific for chronic wounds, reducing in this way their amount by 30-45 % in the wound bed without entirely inhibiting their activity, as the latter is necessary for the wound healing process. The hydrogels were also shown to be non-cytotoxic as well as to prevent the biofilm formation of S. Aureus. The in vivo implantation in rats showed no immune response to moderate immune reaction for both studied PCB hydrogels. Thus, the properties of the PCB networks revealed in the study demonstrate their potential as chronic wounds dressing materials.Peer ReviewedPostprint (author's final draft