Development and In Vitro Validation of Antibacterial Paints Containing Chloroxylenol and Terpineol

Development and characterisation of antimicrobial epoxy resin

Surface contamination is an important, if under-discussed, route of infection transmission. In this study, we suspended chlorhexidine digluconate (CHX) in epoxy resin. CHX was found to be stably incorporated into the material, and its addition to epoxy resin was found to have minimal effects on the optical transparency of the material. After application of the epoxy resin to steel surfaces, time-of-flight secondary ion mass spectrometry revealed that CHX was uniformly present over the surface. Surfaces painted with CHX-resin were found to have significant, reproducible antimicrobial efficacy against E. coli, S. aureus, and C. albicans. We have shown that the addition of CHX has minimal effects on the adhesion of the epoxy resin to surfaces, as well as a high durability of the antimicrobial efficacy. We believe that this material has a wide array of applications, and could be utilised to confer significant, low-cost antimicrobial efficacy to existing surfaces, to prevent surface contamination, and to stop the transmission of infectious disease.

A strategy of extracting and purifying the α-terpineol obtained from the Penicillium digitatum biotransformation of limonene

α-Terpineol, an abundant oxygenated monoterpene compound, shows a varied range of beneficial bioactivities. This study focused on the efficient extraction and purification of α-terpineol from the biotransformation of limonene using Penicillium digitatum DSM 62840 mutant (PdTP1-overexpressed OE2 strain). The α-terpineol was primarily distributed in the supernatant, with minimal association with the biomass. And the optimal extraction was achieved using ethyl acetate as the extractant, which can directly obtain the highest recovery of α-terpineol without sequential extractions. The equilibrium of mass transfer was quickly reached (≤20 s in vortex). Additionally, the purification method of α-terpineol using column chromatography was described, further improving the purity of product to 96.86% in gas chromatography. Structural identification of purified α-terpineol was confirmed using gas chromatography-mass spectrometry, Fourier-transform infrared spectroscopy, and nuclear magnetic resonance. This simplified and efficient strategy for the extraction and purification of α-terpineol not only provides a solid theoretical basis for the final step in the relevant study of microbial synthesis of α-terpineol but also is of great significance for its industrial application.

Film Formation of Iodinated Latex Dispersions and Its Role in Their Antimicrobial Activity

Waterborne coatings with intrinsic antibacterial attributes have attracted significant attention due to their potential in mitigating microbial contamination while simultaneously addressing the environmental drawbacks of their solvent-based counterparts. Typically, antimicrobial coatings are designed to resist and eliminate microbial threats, encompassing challenges such as biofilm formation, fungal contamination, and proliferation of black mold. Iodine, when solubilized using ethylene glycol and incorporated as a complex into waterborne latex dispersions, has shown remarkable antimicrobial activity. Here, we demonstrate the effect of the film formation process of these iodinated latex dispersions on their antimicrobial properties. The effect of iodine on the surface morphology and mechanical, adhesion, and antimicrobial properties of the generated films was investigated. Complete integration and uniform distribution of iodine in the films were confirmed through UV-vis spectrophotometry and a laser Raman imaging system (LRIS). In terms of properties, iodinated films showed improved mechanical strength and adhesion compared with blank films. Further, the presence of iodine rendered the films rougher, making them susceptible to bacterial adhesion, but interestingly provided enhanced antibiofilm activity. Moreover, thicker films had a lower surface roughness and reduced biofilm growth. These observations are elucidated through the complex interplay among film thickness, surface morphology, and iodine properties. The insights into the interlink between the film formation process and antimicrobial properties of iodinated latex dispersions will facilitate their enhanced application as sustainable alternatives to solvent-based coatings.

Assessing Antimicrobial Efficacy on Plastics and Other Non-Porous Surfaces: A Closer Look at Studies Using the ISO 22196:2011 Standard

The survival and spread of foodborne and nosocomial-associated bacteria through high-touch surfaces or contamination-prone sites, in either healthcare, domestic or food industry settings, are not always prevented by the employment of sanitary hygiene protocols. Antimicrobial surface coatings have emerged as a solution to eradicate pathogenic bacteria and prevent future infections and even outbreaks. Standardised antimicrobial testing methods play a crucial role in validating the effectiveness of these materials and enabling their application in real-life settings, providing reliable results that allow for comparison between antimicrobial surfaces while assuring end-use product safety. This review provides an insight into the studies using ISO 22196, which is considered the gold standard for antimicrobial surface coatings and examines the current state of the art in antimicrobial testing methods. It primarily focuses on identifying pitfalls and how even small variations in methods can lead to different results, affecting the assessment of the antimicrobial activity of a particular product.

Rapid-killing efficacy substantiates the antiseptic property of the synergistic combination of carvacrol and nerol against nosocomial pathogens

Globally, new classes of synthetic and natural antibiotics and antivirulents have continuously been validated for their potential broad-spectrum antagonistic activity with the aim of identifying an effective active molecule to prevent the spread of infectious agents in both food industry and medical field. In view of this, present study is aimed at evaluating the rapid killing efficacy of bioactive molecules Carvacrol (C) and Nerol (N) through British Standard European Norm 1276: phase2/step1 (EN1276) protocol. Active molecules C and N showed broad-spectrum antimicrobial activity against the test strains Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus hirae at concentration range of 78.125, 625, 156.25 and 312.5 μg/mL, respectively, for C, and 625 μg/mL for N. Whereas, combinatorial approach showed efficient activity with four times reduced concentration of C and N at 78.125 and 156.25 µg/mL, respectively, against test strains. Further, EN1276 results proved the rapid killing efficacy of test strains in 1 min of contact time with significant (> 5 log) growth reduction at 100X concentration of actives. SEM analysis and reduced concentration of protease, lipids and carbohydrate contents of treated group biofilm components ascertained preformed biofilm disruption potential of C + N on polystyrene and nail surfaces. C + N at synergistic concentration exhibited no adverse effect on HaCaT cells at 78.125 µg/mL (C) + 156.25 µg/mL (N). Taken together, based on the observed experimental results, present study evidence the antiseptic/disinfectant ability of C + N and suggest that the combination can preferentially be used in foam-based hand wash formulations.