Staphylococcus epidermidis is a safer surrogate of Staphylococcus aureus in testing bacterial filtration efficiency of face masks

Face masks play a role in reducing the spread of airborne pathogens, providing that they have a good filtration performance, are correctly fitted and maintained. Bacterial Filtration Efficiency (BFE) is a key indicator for evaluating filtration performance according to both European and US standards, requiring the use of Staphylococcus aureus loaded aerosol. However, the generation and handling of a Biohazard group 2 bacterium aerosol require a careful management of the biological risk and pose limitations to the accessibility to this method. To mitigate these drawbacks, we investigated the use of S. epidermidis ATCC 12228, a Biohazard group 1 bacterium, as surrogate in BFE test. To this end, tests with the surrogate strain were performed to tune the method. Then, three face mask models, representative for both surgical and community masks, were tested according to the standard method and then using an aerosolized suspension of S. epidermidis. BFE% values were calculated for each mask model and tested microorganisms. Results showed that BFE test can be performed using the S. epidermidis instead of S. aureus, preserving results validity and turnaround time, but reducing residual risk for laboratory operators

Fabrication of anisotropically aligned nanofibrous scaffolds based on natural/synthetic polymer blends reinforced with cellulose nanocrystals for tendon tissue engineering

[Excerpt] Introduction: Tendon disorders and injuries are among the most common musculoskeletal problems and their regeneration after injury remains a significant challenge. Given the prevalent fibrous nature of tendons’ ECM, which exhibits an aligned and hierarchical organization in structures from the nano to the macro scale, uniaxial aligned electrospun nanofibers produced from natural/synthetic polymer blends are among the most successful tendon scaffolds in tissue engineering (TE) strategies[1]. These biomaterials can provide the topographical cues to direct cell adhesion and proliferation, as well as positively affecting cell’s differentiation, phenotype maintenance and matrix deposition. However, the limited mechanical properties of electrospun biomaterials restrict their potential application in this field. In the present study, we propose the use of cellulose nanocrystals (CNCs), the “nature carbon nanotubes”, as a strategy for the reinforcement of electrospun poly­ɛ­caprolactone­chitosan (PCL­C) nanofiber scaffolds without compromising their biological performance and thus expand their potential range of application in tendon TE strategies. (...

A Thermal‐Reflow‐Based Low‐Temperature, High‐Pressure Sintering of Lyophilized Silk Fibroin for the Fast Fabrication of Biosubstrates

Solid fibroin is a bulk nonporous material that can be prepared with two methods: a liquid–gel–solid transition from a fibroin solution or a sintering procedure starting from silk powder. Both methods have their own disadvantages: the first requires several weeks and the process is size dependent; the second requires high temperatures. To overcome these limitations, a low‐temperature sintering procedure based on a thermal‐reflow is proposed in this work to produce in fast‐fashion monoliths of solid fibroin. Thermal‐reflow is a well‐known mechanism that takes place when the glass transition temperature of the material is lower than the temperature used to process it. Water plays an important role decreasing the glass transition temperature down to 40 °C. For the first time, a thermal reflow is conducted on lyophilized silk fibroin at 40 °C, associating to the water addition a high‐pressure compression. To optimize the process, a full factorial design of experiment is used. The material is then studied in the crucial phases by digital scanning calorimetry, Fourier‐transform infrared spectroscopy, and scanning electron microscopy. Finally, a mechanical characterization and a preliminary in vitro test are conducted

A Thermal‐Reflow‐Based Low‐Temperature, High‐Pressure Sintering of Lyophilized Silk Fibroin for the Fast Fabrication of Biosubstrates

Solid fibroin is a bulk nonporous material that can be prepared with two methods: a liquid–gel–solid transition from a fibroin solution or a sintering procedure starting from silk powder. Both methods have their own disadvantages: the first requires several weeks and the process is size dependent; the second requires high temperatures. To overcome these limitations, a low‐temperature sintering procedure based on a thermal‐reflow is proposed in this work to produce in fast‐fashion monoliths of solid fibroin. Thermal‐reflow is a well‐known mechanism that takes place when the glass transition temperature of the material is lower than the temperature used to process it. Water plays an important role decreasing the glass transition temperature down to 40 °C. For the first time, a thermal reflow is conducted on lyophilized silk fibroin at 40 °C, associating to the water addition a high‐pressure compression. To optimize the process, a full factorial design of experiment is used. The material is then studied in the crucial phases by digital scanning calorimetry, Fourier‐transform infrared spectroscopy, and scanning electron microscopy. Finally, a mechanical characterization and a preliminary in vitro test are conducted

A Simple Method to Quantify Outward Leakage of Medical Face Masks and Barrier Face Coverings: Implication for the Overall Filtration Efficiency

Face masking proved essential to reduce transmission of COVID-19 and other respiratory infections in indoor environments, but standards and literature do not provide simple quantitative methods for quantifying air leakage at the face seal. This study reports an original method to quantify outward leakage and how wearing style impacts on leaks and filtration efficiency. The amount of air leakage was evaluated on four medical masks and four barrier face coverings, exploiting a theoretical model and an instrumented dummy head in a range of airflows between 30 and 160 L/min. The fraction of air leaking at the face seal of the medical masks and barrier face coverings ranged from 43% to 95% of exhaled air at 30 L/min and reduced to 10–85% at 160 L/min. Filter breathability was the main driver affecting both leak fraction and total filtration efficiency that varied from 5% to 53% and from 15% to 84% at 30 and 160 L/min, respectively. Minor changes were related to wearing style, supporting indications on the correct mask use. The fraction of air leaking from medical masks and barrier face coverings during exhalation is relevant and varies according to design and wearing style. The use of highly breathable filter materials reduces air leaks and improve total filtration efficiency

Rhamnolipid 89 Biosurfactant Is Effective against <i>Streptococcus oralis</i> Biofilm and Preserves Osteoblast Behavior: Perspectives in Dental Implantology

Biofilm-related peri-implant diseases represent the major complication for osteointegrated dental implants, requiring complex treatments or implant removal. Microbial biosurfactants emerged as new antibiofilm coating agents for implantable devices thanks to their high biocompatibility. This study aimed to assess the efficacy of the rhamnolipid 89 biosurfactant (R89BS) in limiting Streptococcus oralis biofilm formation and dislodging sessile cells from medical grade titanium, but preserving adhesion and proliferation of human osteoblasts. The inhibitory activity of a R89BS coating on S. oralis biofilm formation was assayed by quantifying biofilm biomass and microbial cells on titanium discs incubated up to 72 h. R89BS dispersal activity was addressed by measuring residual biomass of pre-formed biofilms after rhamnolipid treatment up to 24 h. Adhesion and proliferation of human primary osteoblasts on R89BS-coated titanium were evaluated by cell count and adenosine-triphosphate quantification, while cell differentiation was studied by measuring alkaline phosphatase activity and observing mineral deposition. Results showed that R89BS coating inhibited S. oralis biofilm formation by 80% at 72 h and dislodged 63–86% of pre-formed biofilms in 24 h according to concentration. No change in the adhesion of human osteoblasts was observed, whereas proliferation was reduced accompanied by an increase in cell differentiation. R89BS effectively counteracts S. oralis biofilm formation on titanium and preserves overall osteoblasts behavior representing a promising preventive strategy against biofilm-related peri-implant diseases

Antimicrobial Personal Protection Clothing: Development of Visible Light Activated Antimicrobial Coatings for Nonwoven Polypropylene Fibers

Abstract During the COVID‐19 pandemic, the use of polypropylene fleece‐based personal protection equipment (PPE) increased significantly to over ten million tons. Typically, most PPEs are discarded after a single use, to prevent self‐infection of users and spread of infectious agents. However, in order to minimize plastic waste without compromising the protective properties of PPE, it is crucial to explore new reusable or longer‐lived materials. Here, a visible light‐activatable antimicrobial photodynamic dye coating for PPEs is presented. In this context, coating with thiomorpholino‐methylene blue (TMB), derived from methylene blue by introducing two thiomorpholine units, is found to show high antibacterial activity. TMB is integrated into rotary printing suspension, a commercial nitrocellulose‐based printing matrix. The concentration of TMB in adhesive is optimized, and found that 5% TMB is suitable for coating PPE, for reducing the number of Gram‐positive and ‐negative bacteria by 99.99% after 6 h of white light irradiation. Bacterial filtration efficiency and breathability tested according to EN 14683, confirmed that TMB coating does not affect the filter performance. Thus, this antimicrobial photodynamic dye coating technique offers a promising solution for a safer and extended use of PPE, and reduction of plastic waste generated by PPEs

Heparin functionalization increases retention of TGF-β2 and GDF5 on biphasic silk fibroin scaffolds for tendon/ligament-to-bone tissue engineering

The tendon/ligament-to-bone transition (enthesis) is a highly specialized interphase tissue with structural gradients of extracellular matrix composition, collagen molecule alignment and mineralization. These structural features are essential for enthesis function, but are often not regenerated after injury. Tissue engineering is a promising strategy for enthesis repair. Engineering of complex tissue interphases such as the enthesis is likely to require a combination of biophysical, biological and chemical cues to achieve functional tissue regeneration. In this study, we cultured human primary adipose-derived mesenchymal stem cells (AdMCs) on biphasic silk fibroin scaffolds with integrated anisotropic (tendon/ligament-like) and isotropic (bone/cartilage like) pore alignment. We functionalized those scaffolds with heparin and explored their ability to deliver transforming growth factor β2 (TGF-β2) and growth/differentiation factor 5 (GDF5). Heparin functionalization increased the amount of TGF-β2 and GDF5 remaining attached to the scaffold matrix and resulted in biological effects at low growth factor doses. We analyzed the combined impact of pore alignment and growth factors on AdMSCs. TGF-β2 and pore anisotropy synergistically increased the expression of tendon/ligament markers and collagen I protein content. In addition, the combined delivery of TGF-β2 and GDF5 enhanced the expression of cartilage markers and collagen II protein content on substrates with isotropic porosity, whereas enthesis markers were enhanced in areas of mixed anisotropic/isotropic porosity. Altogether, the data obtained in this study improves current understanding on the combined effects of biological and structural cues on stem cell fate and presents a promising strategy for tendon/ligament-to-bone regeneration. STATEMENT OF SIGNIFICANCE: Regeneration of the tendon/ligament-to-bone interphase (enthesis) is of significance in the repair of ruptured tendons/ligaments to bone to improve implant integration and clinical outcome. This study proposes a novel approach for enthesis regeneration based on a biomimetic and integrated tendon/ligament-to-bone construct, stem cells and heparin-based delivery of growth factors. We show that heparin can keep growth factors local and biologically active at low doses, which is critical to avoid supraphysiological doses and associated side effects. In addition, we identify synergistic effects of biological (growth factors) and structural (pore alignment) cues on stem cells. These results improve current understanding on the combined impact of biological and structural cues on the multi-lineage differentiation capacity of stem cells for regenerating complex tissue interphases

Narrative del disturbo da gioco d’azzardo e del disturbo da uso di sostanze. Una analisi multidimensionale per la caratterizzazione di possibili marcatori narrativi e linguistici delle dipendenze

Diversi studi hanno dimostrato che l’analisi della dimensione narrativa può rappresentare un valido strumento per far luce su alcuni aspetti psicologici critici; in questo senso, può essere utile per capire meglio il disturbo da dipendenza. Il presente articolo riporta tra l’altro alcuni tra i dati principali di una ricerca da noi condotta e pubblicata nella rivista Journal of Gambling Issues nel 2021. In tale ricerca abbiamo indagato gli aspetti psicologico-narrativi coinvolti nelle dipendenze, specificamente nel DUS e nel DGA, attraverso un’analisi quali-quantitativa multidimensionale di un’intervista semi-strutturata, che ha invitato due gruppi di soggetti dipendenti in trattamento (DGA e DUS) a raccontare le varie fasi della dipendenza. Le analisi narrative multidimensionali da noi condotte sembrano aver portato alla luce alcuni punti critici su cui focalizzare l’attenzione per la costruzione di un adeguato trattamento dei soggetti con dipendenza. Nello specifico, i risultati suggerirebbero la necessità di lavorare su aspetti dissociati del Sé al fine di: 1) favorire il processo di integrazione di motivazioni e azioni, aumentando la consapevolezza e il senso di autoefficacia, soprattutto con i giocatori d’azzardo; 2) migliorare la coerenza globale nella narrazione del desiderio al fine di diminuire la disregolazione emotiva tipica di questa fase; 3) migliorare la capacità di proiezione del Sé nel tempo. Quest’ultimo punto potrebbe essere particolarmente rilevante in una prospettiva di intervento riabilitativo, soprattutto per quanto riguarda gli strumenti di trattamento legati alla dimensione narrativa. Il rapporto circolare tra regolazione dell’impulsività, autocontrollo, integrità dell’Io, funzioni cognitive e dimensione narrativa trova nel fattore temporale uno dei principali perni comuni