Silk fibroin-based dressings with antibacterial and anti-inflammatory properties

Silk fibroin is a fibrillar protein obtained from arthropods such as mulberry and non-mulberry silkworms. Silk fibroin has been used as a dressing in wound treatment for its physical, chemical, mechanical, and biological properties. This systematic review analyzed studies from PubMed, Web of Science, and Scopus databases to identify the molecules preferred for functionalizing silk fibroin-based dressings and to describe their mechanisms of exhibiting anti-inflammatory and antibacterial properties. The analysis of the selected articles allowed us to classify the dressings into different conformations, such as membranes, films, hydrogels, sponges, and bioadhesives. The incorporation of various molecules, including antibiotics, natural products, peptides, nanocomposites, nanoparticles, secondary metabolites, growth factors, and cytokines, has allowed the development of dressings that promote wound healing with antibacterial and immunomodulatory properties. In addition, silk fibroin-based dressings have been established to have the potential to regenerate wounds such as venous ulcers, arterial ulcers, diabetic foot, third-degree burns, and neoplastic ulcers. Evaluation of the efficacy of silk fibroin-based dressings in tissue engineering is an area of great activity that has shown significant advances in recent years.

Scale-Up of the Fermentation Process for the Production and Purification of Serratiopeptidase Using Silkworm Pupae as a Substrate

Serratiopeptidase, a bacterial metalloprotease known for its pain-relieving and anti-inflammatory properties, can be produced through fermentation with S. marcescens. This study aimed to identify key factors related to nutrient composition and physicochemical conditions for production in Erlenmeyer flasks and to scale up the mixture to a bioreactor to obtain the maximum proteolytic activity. A Plackett-Burman design was used to determine whether the presence of silkworm pupae (at 1.5%) was a significant parameter for serratiopeptidase production. Along with the variables pH, temperature, and time, they were optimized using a Taguchi experimental design, resulting in values of 7, 25 °C, and 36 h, respectively. Scaling up with a kLa of 25.45 ± 3.12 h-1 showed the highest serratiopeptidase production at 24 h. A factorial design was used for ultrafiltration, resulting in an LMH (liters per square meter per hour) of 960 L/m2h, a TMP (transmembrane pressure) of 15 psi, and a concentration factor of five, with a specific activity of 24,325.81 ± 1515.69 U/mg. Afterward, the retentate was purified using strong anion exchange chromatography and ultrafiltration, yielding a 19.94 ± 3.07% recovery and a purification factor of 1.59 ± 0.31. In conclusion, waste from the sericulture industry can be used for serratiopeptidase production.

Recent molecular techniques for the diagnosis of Zika and Chikungunya infections: A systematic review

Zika virus (ZIKV) and Chikungunya virus (CHIKV) are arboviruses that cause important viral diseases affecting the world population. Both viruses can produce remarkably similar clinical manifestations, co-circulate in a geographic region, and coinfections have been documented, thus making clinical diagnosis challenging. Therefore, it is urgent to have better molecular techniques that allow a differential, sensitive and rapid diagnosis from body fluid samples. This systematic review explores evidence in the literature regarding the advances in the molecular diagnosis of Zika and Chikungunya in humans, published from 2010 to March 2021. Four databases were consulted (Scopus, PubMed, Web of Science, and Embase) and a total of 31 studies were included according to the selection criteria. Our analysis highlights the need for standardization in the report and interpretation of new promising diagnostic methods. It also examines the benefits of new alternatives for the molecular diagnosis of these arboviruses, in contrast to established methods.

Silk fibroin nanocomposites as tissue engineering scaffolds - A systematic review

Silk fibroin is a protein with intrinsic characteristics that make it a good candidate as a scaffold for tissue engineering. Recent works have enhanced its benefits by adding inorganic phases that interact with silk fibroin in different ways. A systematic review was performed in four databases to study the physicochemical and biological performance of silk fibroin nanocomposites. In the last decade, only 51 articles contained either in vitro cell culture models or in vivo tests. The analysis of such works resulted in their classification into the following scaffold types: particles, mats and textiles, films, hydrogels, sponge-like structures, and mixed conformations. From the physicochemical perspective, the inorganic phase imbued in silk fibroin nanocomposites resulted in better stability and mechanical performance. This review revealed that the inorganic phase may be associated with specific biological responses, such as neovascularisation, cell differentiation, cell proliferation, and antimicrobial and immunomodulatory activity. The study of nanocomposites as tissue engineering scaffolds is a highly active area mostly focused on bone and cartilage regeneration with promising results. Nonetheless, there are still many challenges related to their application in other tissues, a better understanding of the interaction between the inorganic and organic phases, and the associated biological response.

Verificación del desempeño de la prueba rápida "AMP Rapid Test SARS-CoV-2 IgG/IgM- Cassettes"

Objetivo: Verificación del desempeño de las pruebas serológicas rápidas utilizadas en el departamento de Risaralda, Colombia. Métodos: Estudio analitico, de corte transversal. Incluyó muestras de sueros de trabajadores de la salud de la ciudad de Pereira, quienes tuvieron sospecha clínica y epidemiológica por SARS-CoV-2. El procesamiento y validación de las pruebas fue realizado en las instalaciones de la Universidad Tecnológica de Pereira. Se calculó sensibilidad y especificidad de las pruebas rápidas serológicas IgM/IgG usando como prueba de oro la RT-PCR. Resultados: Se incluyeron las muestras de 144 profesionales de la salud. Las pruebas serológicas rápidas evidenciaron ser útiles para identificar o descartar la presencia de anticuerpos IgM e IgG, especialmente en pacientes sintomáticos, en quienes el inicio de los síntomas es superior a 11 días. Discusión: El uso de pruebas rápidas se encuentra en aumento, no solo por la rapidez de sus resultados, sino también por los bajos costos asociados y la necesidad de identificar pacientes no susceptibles, quienes deben priorizar su retorno a actividades laborales en comunidad como parte de la reactivación económica de Colombia. Es necesario confirmar el desempeño de la prueba para aumentar la probabilidad de una adecuada clasificación antes de proceder a su uso rutinario.

Silk fibroin hydrogels from the Colombian silkworm Bombyx mori L: Evaluation of physicochemical properties

Hydrogel scaffolds are important materials in tissue engineering, and their characterization is essential to determine potential biomedical applications according to their mechanical and structural behavior. In this work, silk fibroin hydrogels were synthesized by two different methods (vortex and sonication), and agarose hydrogels were also obtained for comparison purposes. Samples were characterized by scanning electron microscopy, infrared analysis, thermo-gravimetrical analysis, confined compression test, and rheological test. The results indicate that nanofibers can be obtained via both silk fibroin and agarose hydrogels. The mechanical tests showed that the Young's modulus is similar to those found in the literature, with the highest value for agarose hydrogels. All the hydrogels showed a shear-thinning behavior. Additionally, the MTT test revealed that silk fibroin hydrogels had low cytotoxicity in THP-1 and HEK-293 cells, whereas the agarose hydrogels showed high toxicity for the THP-1 cell line. The results indicate that silk fibroin hydrogels obtained from a Colombian silkworm hybrid are suitable for the development of scaffolds, with potential applications in tissue engineering.