Inactivation kinetics of some microorganisms in apple,melon, orange and strawberry juices by high intensity light pulses

The suitability of some models was analyzed to characterize the Pulsed Light (PL) inactivation kinetics for Escherichia coli ATCC 35218, Listeria innocua ATCC 33090, Salmonella Enteritidis MA44 and Saccharomyces cerevisiae KE162 in commercial juices and fresh squeezed juices. A negative relationship was found between the absorbance of juices and PL effectiveness. PL treatment (2.4–71.6 J/cm²) was ineffective in natural strawberry and orange juices. In general, inactivation curves exhibited a marked upward concavity, reaching after 60 s-PL treatment to 0.3–6.9 log-reduction cycles. Nonlinear semilogarithmic survival curves were fitted by conceptually different models: the Weibull model, the biphasic model and a modified version of the Coroller model. Biphasic and Weibull models compared to the modified Coroller model allowed a better fit and more accurate estimation of parameters. A multivariate approach to data analysis by principal components (PCA) showed relevant spatial relationships among estimated model parameters, revealing PL treatment efficacy in the different juices.     

Development of a Device for Dynamic Simulation of the Breathing System to Evaluate a Functional Nonwoven Fabric Coated with Cu Film

One of the challenges to evaluate the performance of functional materials for face masks is to look for a dynamic interaction with biological samples. A device for dynamic simulation of breathing system is constructed and dynamic and static responses of a polypropylene (C₃H₆)_n nonwoven fabric coated with Cu film by magnetron-sputtering process, against Escherichia coli, are analyzed. The use of scanning electron microscopy, energy-dispersive spectroscopy, and the 3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) indirect method using the L929 mouse fibroblasts, and the procedure of Antibacterial Activity of Textile Materials: Parallel Streak (TM147) from American Association of Textile Chemists and Colorists (AATCC) using E. coli and Staphylococcus aureus strains, allows to evaluate the morphological, physicochemical, and biological static performance of the obtained composite. No leaching of the deposited Cu film in the substrate is observed after using the device for dynamic simulation of breathing system. The permeability coefficient of the nonwoven fabric is obtained, equivalent to 71.4 Pa cm⁻². By the dynamic response against E. coli bacteria, the best bactericidal activity is observed for S960 with the maximum Cu concentration, presenting a high potential for application as a functional layer in facial masks.     

Deconstructing the Potency and Cell-Line Selectivity of Membranolytic Anticancer Peptides**

Current cancer treatments damage healthy cells and tissues, causing short-term and long-term side effects. New treatments are desired that show greater selectivity toward cancer cells and evade the common mechanisms of multidrug resistance. Membranolytic anticancer peptides (mACPs) hold promise against cancer and multidrug resistance. Amphipathicity, hydrophobicity, and net charge of mACPs participate in their respective interactions with cell membranes and their overall inhibition of cancer cells. To support the design of cell-line selective mACPs, we investigated the relationships that amino acid composition, physicochemical properties, sequence motifs, and sequence homology could have with their potency and selectivity towards several healthy and cancer cell lines. Sequence length and net charge are known to affect the selectivity of mACPs between cancer and healthy cell lines. Our study reveals that increasing the net charge or flexibility (i. e., small and aliphatic residues) influences their selectivity between cancer cell lines with comparable lipid compositions.