Advantages of FDM and gamma irradiation to manufacture personalized medical devices for airway obstructions.

In the early childhood population, congenital airway conditions like bronchomalacia (BM) can pose a life-threatening threat. A breakthrough technology called additive manufacturing, or 3D printing, makes it feasible to create a biomedical device that aids in the treatment of airway obstruction. This article describes how a polycaprolactone (PCL) splint for the upper airways can be created using the fusion deposition technique (FDM) and sterilized using gamma radiation. It is presented as a simple, accessible, and cost-reduced alternative that complements other techniques using more expensive and sophisticated printing methods. Thermomechanical and morphological analysis proved that FDM and sterilizing by gamma irradiation are both appropriate methods for producing splints to treat life-threatening airway blockages. Additionally, the 3D-printed splints' effectiveness in treating a young patient with BM that was life-threatening was assessed by medical professionals. In this regard, the case report of a patient with 34 months of follow-up is presented. Splints manufactured by this affordable 3D printing method successfully surpass breathing arrest in life-threatening airway obstruction in pediatric patients. The success of this procedure represents a fundamental contribution to the treatment of the population in countries where access to expensive and complex technologies is not available.

PHA granule formation and degradation by Cupriavidus necator under different nutritional conditions.

Polyhydroxyalkanoates (PHA) are polymers produced by microorganisms with increasing commercialization potential; Cupriavidus necator has been the model microorganism to research PHA production. Despite many contributions concerning the formation and degradation of PHA granules, as well as the morphological changes in cells, these phenomena have not been univocally explained yet. Thus, this study aims to integrate the microscopic and analytical analysis to characterize changes in bacterial cell/PHA granules morphology, PHA content, and yield coefficients under different cultivation strategies of C. necator ATCC 17697. The cell size and morphology, granule size and amount, residual biomass, and PHA concentration along the fermentation and degradation depend greatly on nutritional conditions and cultivation time of C. necator. It was proposed to calculate a yield coefficient for the residual biomass production in the PHA utilization stage, related to the bacteria's ability to survive without a carbon source in the culture medium by utilizing the accumulated PHA previously. Maximum granule length reached 1.07 µm after 72 h of PHA accumulation stage under optimum nutritional conditions. This value is twice the values previously reported for C. necator. It is important since the larger PHA granules facilitate the recovery of PHA and different application development.

Erratum to "Improved fermentation strategies in a bioreactor for enhancing poly(3-hydroxybutyrate) (PHB) production by wild type Cupriavidus necator from fructose" [Heliyon 7 (1) (January 2021) Article e05979].

[This corrects the article DOI: 10.1016/j.heliyon.2021.e05979.].

Improved fermentation strategies in a bioreactor for enhancing poly(3-hydroxybutyrate) (PHB) production by wild type Cupriavidus necator from fructose.

Poly(3-hydroxybutyrate) (PHB) belongs to the family of polyhydroxyalkanoates, biopolymers used for agricultural, industrial, or even medical applications. However, scaling up the production is still an issue due to the myriad of parameters involved in the fermentation processes. The present work seeks, firstly, to scale up poly(3-hydroxybutyrate) (PHB) production by wild type C. necator ATCC 17697 from shaken flasks to a stirred-tank bioreactor with the optimized media and fructose as carbon source. The second purpose is to improve the production of PHB by applying both the batch and fed-batch fermentation strategies in comparison with previous works of wild type C. necator with fructose. Furthermore, thinking of biomedical applications, physicochemical, and cytotoxicity analyses of the produced biopolymer, are presented. Fed-batch fermentation with an exponential feeding strategy enabled us to achieve the highest values of PHB concentration and productivity, 25.7 g/l and 0.43 g/(l h), respectively. The PHB productivity was 3.3 and 7.2 times higher than the one in batch strategy and shaken flask cultures, respectively. DSC, FTIR, 1H, and 13C NMR analysis led to determine that the biopolymer produced by C. necator ATCC 17697 has a molecular structure and characteristics in agreement with the commercial PHB. Additionally, the biopolymer does not induce cytotoxic effects on the NIH/3T3 cell culture. Due to the improved fermentation strategies, PHB concentration resulted in 40 % higher of the already reported one for wild type C. necator using other fed-batch modes and fructose as a carbon source. Thus the produced PHB could be attractive for biomedical applications, which generate a rising interest in polyhydroxyalkanoates during recent years.

Biompresión 3D de piel / 3D skin bioprinting

La impresión 3D es un proceso que convierte gráficos 3D en objetos tridimensionales de manera similar a imprimir en 2D sobre un papel. Se imprime en 3D un trozo de piel de diferentes tipos de células humanas cul-tivadas in vitro o células epidérmicas incorporadas en un solo paso, utilizando una impresora 3D en la que la tinta biológica está compuesta por células vivas en suspensión en un líquido y preparado en un cartucho, siendo expulsada mediante flujo continuo. Esta sustancia contiene diferentes tipos de células: fibroblastos, queratinocitos y melanocitos que constituyen la epidermis. La bioimpresión 3D de piel facilita la fabricación de un modelo de piel humana más compleja que incorpora estructuras secundarias y anexiales para lograr un avance en nuestra comprensión de la piel humana como un órgano, lo que permite la bioingeniería de injertos en el tratamiento de diferentes enfermedades de la piel, así como en el paciente quemado

3D printing is a process that converts 3D graphics dimensional objects similarly 2D printing on paper. 3D is printed on a piece of skin of different types of cultured human cells in vitro using a 3D printer that biological ink are composed of living cells in suspension in a liquid and made into a cartridge; it is expelled by a laser. This substance contains different types of cells: fibroblasts, keratinocytes and melanocytes which constitute the epidermis. 3D printing skin facilitates manufacture of a more complex model incorporating secondary human skin and anexal structures to achieve a breakthrough in our understanding of human skin as an organ, allowing the graft engineering in treatment of various skin diseases and burn patients

Evaluation of culture medium on poly(3-hydroxybutyrate) production by Cupriavidus necator ATCC 17697: application of the response surface methodology.

Polyhydroxyalkanoates (PHA), of which polyhydroxybutyrate (PHB) is the most abundant, are polymers of bacterial origin used for various applications in the medical, industrial and agricultural fields. In the present study we worked on the selection, evaluation and improvement of the significant variables of the medium for the production of PHB by Cupriavidus necator ATCC 17697. In order to address the selection of the main factors and optimize the culture medium, a complete factorial experimental design based on the coupled response surface methodology, was presented. The model with the best adjustment of the variables turned out to be quadratic in fructose (C), linear in ammonium sulphate (N) and pH, with interaction in pH and phosphate solution (P), where the pH was the most significant (p < 0.0001) while the micro-elements solution could be neglected. Thus, optimum carbon concentration, adequate nitrogen limitation and interaction between initial pH and phosphate solution concentration are important factors to ensure a high production of PHB. The optimal values of the selected variables were C = 20 g/l, N = 1.5 g/l, P = 8.75 g/l and pH 7.5. A maximum PHB production of 4.6 g/l, obtained under these conditions, increased almost 2.5 times. The polymer accumulated in the cytoplasm of C. necator ATCC 17697 in the form of granules showed an FTIR spectrum corresponding to that of commercial PHB.

Phenomenological models for the isothermal physical aging of PEEK.

Creep test is a useful tool to study thermal aging and deformation mechanisms of semi-crystalline polymers, such as polyether-ether-ketone (PEEK). Hou and Chen proposed a power law to fit creep data of PEEK aged at different temperatures and the master curve built from those data. This paper attempts to complement that analysis by introducing Kohlrausch function as an alternative to the fractional Maxwell's model associated to the power law. Although the fitting of experimental data and the mathematical conditions imposed to equations that describe curves that can be superimposed by translations, are obeyed by both models, this paper demonstrates that Kohlrausch function provides a better phenomenological description of the creep response of PEEK due to the physical interpretation of the fitting parameters and their dependence on the aging time and temperature.

Could essential oils enhance biopolymers performance for wound healing? A systematic review.

BACKGROUND: Millions of people in the world suffer from chronic wounds of different etiologies such as diabetic foot and leg ulcers, without solutions nowadays. Molecules obtained from plants offer an alternative to aid wound healing. Strong evidence about essential oils (EO) anti-inflammatory and antimicrobial properties is thoroughly described in literature and their chemical compositions are well characterized. More recently, EO effects in experimental wounds have begun to be analyzed. AIM: We aim to summarize the evidence of EO in experimental wounds, and the possibility of combining them with biopolymers commonly used in skin regeneration. METHODS: Electronic databases such as ScienceDirect, PubMed and Scopus were used to search scientific contributions until March 2017, using relevant keywords. In a first step, literature focusing on EO and/or mono- or sesqui-terpenoids effects in rodent wounds was identified and summarized. In all cases, chemical structures and EO composition were detailed, as well as references to in vitro activities previously determined, e.g. antibacterial, antioxidant or anti-inflammatory. In a second step, scientific literature devoted to combine EO and biopolymers with the focus set on wound healing innovations, was collected and analyzed. RESULTS: Treatments with EO from species of genders Lavandula, Croton, Blumea, Eucalyptus, Pinus, Cymbopogon, Eucalyptus, Cedrus, Abies, Rosmarinus, Origanum, Salvia and Plectranthus, have shown positive results in rodent wounds. All of these EO were mainly composed by monoterpenoids-thymol, 1,8-cineole, linalool-or monoterpenes, as limonene or pinenes. Experimental wounds in rodents have shown faster closure rate, better collagen deposition and/or enhanced fibroblasts proliferation. In blends with biopolymers, several EO combined with chitosan, alginate, gelatin or collagen, were processed to give active films or nanofibers, with antioxidant, anti-inflammatory or antimicrobial activities. Curiously, all of these works were carried out since 2010. CONCLUSIONS: There is significant evidence about the effectivity of EO as wound healers. The incorporation of EO into a polymer matrix that contributes to wound healing is still incipient. However, scientific based evidence of the EO incorporation in resorbable polymeric scaffolds was found and analyzed herein. In summary, EO-biopolymer dressings or scaffolds have become promising artifacts regarding wound treatments, especially in chronic wounds, where treating infection and inflammation are still important issues.

Comportamiento biomecánico de tres cementos de ionómero-resina utilizados para cementar pernos intrarradiculares. Un ensayo "in vitro" / Biomechanical behavior or three glass ionomer-resin cements used for cementing intraradicular posts. An in vitro assay

El objetivo de este trabajo fue evaluar "in vitro" el efecto de los posibles cambios volumétricos desarrollados por los ionómeros vítreos híbridos, cuando son utilizados para cementar pernos intrarradiculares. Se realizaron dos ensayos diferentes: en el ensayo No.1 se utilizaron 20 raíces de vidrio con un espesor de pared de 1 mm., contenidas dentro de tacos cilídricos de acrílico y unidas a ellos por medio de una silicona de mediana viscosidad. En el interior de las raíces se cementaron tornillos que no ejercían ningún tipo de presión, utilizando para ello tres diferentes cementos de ionómero-resina y un cemento de fosfato de cinc (control). Los especímenes fueron sometidos durante 90 días a una carga compresiva de 150 N en un medio acuoso mantenido a temperatura constante de 37 grados C. En el ensayo No.2 se utilizaron los mismos procedimientos experimentales, pero en este caso las raíces presentaban un espesor de pared de 2 mm. En todos los especímenes pertenecientes al ensayo No.1 se verificó la presencia de diferentes grados de fractura: microfracturas escasas y espaciadas en la masa de los cementos (más frecuentes y pronunciadas en la masa de fosfato de cinc) y fracturas totales en las paredes de las raíces artificiales de vidrio. En el ensayo No.2, las paredes de las raíces se encontraban intactas en todos los casos, aunque sí se produjeron microfracturas en la masa de los cementos, las que nuevamente fueron más frecuentes y pronunciadas en el cemento de fosfato de cinc. Los resultados sugieren que el factor determinante en la producción de fracturas en las paredes de las raíces artificiales de vidrio del ensayo No.1 parecería depender del espesor y la resistencia de las mismas y no de los posibles cambios volumétricos ocurridos en la masa de los cementos testeados

Comportamiento biomecánico de tres cementos de ionómero-resina utilizados para cementar pernos intrarradiculares. Un ensayo "in vitro" / Biomechanical behavior or three glass ionomer-resin cements used for cementing intraradicular posts. An in vitro assay

El objetivo de este trabajo fue evaluar "in vitro" el efecto de los posibles cambios volumétricos desarrollados por los ionómeros vítreos híbridos, cuando son utilizados para cementar pernos intrarradiculares. Se realizaron dos ensayos diferentes: en el ensayo No.1 se utilizaron 20 raíces de vidrio con un espesor de pared de 1 mm., contenidas dentro de tacos cilídricos de acrílico y unidas a ellos por medio de una silicona de mediana viscosidad. En el interior de las raíces se cementaron tornillos que no ejercían ningún tipo de presión, utilizando para ello tres diferentes cementos de ionómero-resina y un cemento de fosfato de cinc (control). Los especímenes fueron sometidos durante 90 días a una carga compresiva de 150 N en un medio acuoso mantenido a temperatura constante de 37 grados C. En el ensayo No.2 se utilizaron los mismos procedimientos experimentales, pero en este caso las raíces presentaban un espesor de pared de 2 mm. En todos los especímenes pertenecientes al ensayo No.1 se verificó la presencia de diferentes grados de fractura: microfracturas escasas y espaciadas en la masa de los cementos (más frecuentes y pronunciadas en la masa de fosfato de cinc) y fracturas totales en las paredes de las raíces artificiales de vidrio. En el ensayo No.2, las paredes de las raíces se encontraban intactas en todos los casos, aunque sí se produjeron microfracturas en la masa de los cementos, las que nuevamente fueron más frecuentes y pronunciadas en el cemento de fosfato de cinc. Los resultados sugieren que el factor determinante en la producción de fracturas en las paredes de las raíces artificiales de vidrio del ensayo No.1 parecería depender del espesor y la resistencia de las mismas y no de los posibles cambios volumétricos ocurridos en la masa de los cementos testeados (AU)