A Rapidly Responsive Sensor for Wireless Detection of Early and Mature Microbial Biofilms.

Biofilm-associated infections, which are able to resist antibiotics, pose a significant challenge in clinical treatments. Such infections have been linked to various medical conditions, including chronic wounds and implant-associated infections, making them a major public-health concern. Early-detection of biofilm formation offers significant advantages in mitigating adverse effects caused by biofilms. In this work, we aim to explore the feasibility of employing a novel wireless sensor for tracking both early-stage and matured-biofilms formed by the medically relevant bacteria Staphylococcus aureus and Pseudomonas aeruginosa. The sensor utilizes electrochemical reduction of an AgCl layer bridging two silver legs made by inkjet-printing, forming a part of near-field-communication tag antenna. The antenna is interfaced with a carbon cloth designed to promote the growth of microorganisms, thereby serving as an electron source for reduction of the resistive AgCl into a highly-conductive Ag bridge. The AgCl-Ag transformation significantly alters the impedance of the antenna, facilitating wireless identification of an endpoint caused by microbial growth. To the best of our knowledge, this study for the first time presents the evidence showcasing that electrons released through the actions of bacteria can be harnessed to convert AgCl to Ag, thus enabling the wireless, battery-less, and chip-less early-detection of biofilm formation.

Preparation of terpolymer capsules containing Rosmarinus officinalis essential oil and evaluation of its antifungal activity.

The essential oil from Rosmarinus officinalis presents antifungal activity and is used in industry as a natural preserving agent. However, essential oils are unstable compounds. So, the encapsulation of essential oils is a technique used to protect it, minimizing degradation and reducing undesired interaction with the other formulation components. Thus, this work focuses on the synthesis of terpolymeric capsules containing essential oil from Rosmarinus officinalis, aiming to use it as an antifungal component in cosmetics. The capsules were obtained via terpolymerization of methyl methacrylate, styrene and methacrylic acid in a dispersed phase polymerization process. The properties of the polymers and the fungicide activity were evaluated. The studied essential oil presented a Minimum Inhibitory Concentration (MIC) ranging from 2.25 to 4.5 mg mL-1 and a Minimum Fungicidal Concentration (MFC) from 4.5 to 9.0 mg mL-1 for strains of Candida albicans, Candida glabrata and Candida parapsilosis, and after the encapsulation process, the antifungal activity of the oil was maintained. Additionally, cytotoxicity assays against fibroblast cell lines and human keratinocytes showed that the polymeric nanocapsules containing Rosmarinus officinalis essential oil can be regarded as a very promising material intended for cosmetics and drug delivery applications.