Bactericide Activity of Cellulose Acetate/Silver Nanoparticles Asymmetric Membranes: Surfaces and Porous Structures Role

Abstract

The antibacterial properties of cellulose acetate/silver nanoparticles (AgNP) ultrafiltration membranes were correlated with their integral asymmetric porous structures, emphasizing the distinct features of each side of the membranes, that is, the active and porous layers surfaces. Composite membranes were prepared from casting solutions incorporating polyvinylpyrrolidone-covered AgNP using the phase inversion technique. The variation of the ratio acetone/formamide and the AgNP content resulted in a wide range of asymmetric porous structures with different hydraulic permeabilities. Comprehensive studies assessing the antibacterial activity against Escherichia coli (cell death and growth inhibition of bacteria in water) were performed on both membrane surfaces and in E. coli suspensions. The results were correlated with the surface chemical composition assessed by XPS. The silver-free membranes presented a generalized growth of E. coli, which is in contrast with the inhibition patterns displayed by the membranes containing AgNP. For the surface bactericide test, the growth inhibition depends on the accessibility of E. coli to the silver present in the membrane; as the XPS results show, the more permeable membranes (CA30 and CA34 series) have higher silver signal detected by XPS, which is correlated with a higher growth inhibition. On the other hand, the inhibition action is independent of the membrane porous structure when the membrane is deeply immersed in an E. coli inoculated suspension, presenting almost complete growth inhibition.

Antitumoral and Immunogenic Capacity of β-D-Glucose—Reduced Silver Nanoparticles in Breast Cancer

“…We could determine that the silver solution is exhibited in Ag 0 (metallic) state based on XPS analysis, such as those found by Figueiredo et al 2022 [22] and Du et al 2022 [23] The detailed regions of the XPS analysis show a simple doublet in the Ag3d spectrum with an energy separation of 6.0 eV, where we could also observe the Ag3d5/2 component cen tered at 366.8 eV. Based on the data above and considering the values dispersion reported in the literature for those is correlated with the synthesis of the metallic AgNPs [23,24].…”

Active Cellulose Acetate/Chitosan Composite Films Prepared Using Solution Blow Spinning: Structure and Electrokinetic Properties

“…As can be seen in Figure 4 , all spectra show the typical absorption bands of cellulose acetate. The broad weak band around 3490 cm −1 corresponds to non-esterified hydroxyl groups (OH stretching) of cellulose; the weak bands at 2945 cm −1 and 2886 cm −1 are associated with the CH antisymmetric and symmetric stretching of the methyl group, CH 3 , respectively [ 11 , 45 , 54 ]. The high-intensity absorption band at 1735 cm −1 corresponds to carbonyl stretching in the acetyl group, as expected for cellulose acetate, which does not change upon the addition of chitosan.…”

“…The high-intensity absorption band at 1735 cm −1 corresponds to carbonyl stretching in the acetyl group, as expected for cellulose acetate, which does not change upon the addition of chitosan. The peaks at 1365 cm −1 and 900 cm −1 assigned to the symmetric CH 3 bending and to the acetate methyl groups, respectively, are also typical for cellulose acetate [ 45 , 54 ].…”

Erythrosine–Dialdehyde Cellulose Nanocrystal Coatings for Antibacterial Paper Packaging

“…For the aPDI process, 20 µL of 1.5-wt% Ery-DACNCs solution was mixed with 50 µL of an E. coli suspension and irradiated using green-and white-light-emitting diodes (to simulate real-world lighting conditions). E. coli is a well-characterized bacterium that is commonly used in antibacterial research due to its clear growth characteristics, wellunderstood genetics, and ease of cultivation [27,28]. The effects of different irradiation times (10-30 and 60 min for green light and 20-60 and 90 min for white light) were investigated.…”