BackgroundMultidrug resistant microorganisms are a growing challenge and new substances that can be useful to treat infections due to these microorganisms are needed. Silver nanoparticle may be a future option for treatment of these infections, however, the methods described in vitro to evaluate the inhibitory effect are controversial.ResultsThis study evaluated the in vitro activity of silver nanoparticles against 36 susceptible and 54 multidrug resistant Gram-positive and Gram-negative bacteria from clinical sources. The multidrug resistant bacteria were oxacilin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp., carbapenem- and polymyxin B-resistant A. baumannii, carbapenem-resistant P. aeruginosa and carbapenem-resistant Enterobacteriaceae. We analyzed silver nanoparticles stabilized with citrate, chitosan and polyvinyl alcohol and commercial silver nanoparticle. Silver sulfadiazine and silver nitrate were used as control. Different methods were used: agar diffusion, minimum inhibitory concentration, minimum bactericidal concentration and time-kill. The activity of AgNPs using diffusion in solid media and the MIC methods showed similar effect against MDR and antimicrobial-susceptible isolates, with a higher effect against Gram-negative isolates. The better results were achieved with citrate and chitosan silver nanoparticle, both with MIC90 of 6.75 μg mL−1, which can be due the lower stability of these particles and, consequently, release of Ag+ ions as revealed by X-ray diffraction (XRD). The bactericidal effect was higher against antimicrobial-susceptible bacteria.ConclusionIt seems that agar diffusion method can be used as screening test, minimum inhibitory concentration/minimum bactericidal concentration and time kill showed to be useful methods. The activity of commercial silver nanoparticle and silver controls did not exceed the activity of the citrate and chitosan silver nanoparticles. The in vitro inhibitory effect was stronger against Gram-negative than Gram-positive, and similar against multidrug resistant and susceptible bacteria, with best result achieved using citrate and chitosan silver nanoparticles. The bactericidal effect of silver nanoparticle may, in the future, be translated into important therapeutic and clinical options, especially considering the shortage of new antimicrobials against the emerging antimicrobial resistant microorganisms, in particular against Gram-negative bacteria.

Environmentally friendly energy devices and systems are of increasing interest for the circular economy and sustainable information and communications technology. To this end, an energy‐autonomous system comprised of natural jute fiber‐based supercapacitor (SC) and sensors (temperature and humidity) is presented. This material is coated with poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/single‐walled carbon nanotubes as the electrode and cellulose‐based material as a separator. Further, a newly prepared hydroxyethyl cellulose‐potassium chloride based gel is used as the electrolyte. The observed capacitance is nearly twice the value reported for similar SCs. The energy and power densities of the presented SC are 0.712 μWh cm−1 and 3.85 µW cm−1, respectively at a capacitance of 8.65 mF cm−1 and an applied current of 0.1 mA. The fabricated temperature sensor shows a relative change in response of 0.23% °C−1 from 24 to 35 °C and the humidity sensor exhibits a sensitivity of 1.5 Ω/%RH (relative change of 0.20%) up to 50%RH. Developed using sustainable and biocompatible materials, the presented SC can power the jute‐fiber based sensors, thus demonstrating an attractive eco‐friendly solution for applications such as wearables, grain sacks, and bags.

Electrochemical voltammetric sensors are some of the most promising types of sensors for monitoring various physiological analytes due to their implementation as non-invasive and portable devices. Advantages in reduced analysis time, cost-effectiveness, selective sensing, and simple techniques with low-powered circuits distinguish voltammetric sensors from other methods. In this work, we developed a Cu2O-based non-enzymatic portable glucose sensor on a graphene paste printed on cellulose cloth. The electron transfer of Cu2O in a NaOH alkaline medium and sweat equivalent solution at very low potential (+0.35 V) enable its implementation as a low-powered portable glucose sensor. The redox mechanism of the electrodes with the analyte solution was confirmed through cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy studies. The developed biocompatible, disposable, and reproducible sensors showed sensing performance in the range of 0.1 to 1 mM glucose, with a sensitivity of 1082.5 ± 4.7% µA mM−1 cm−2 on Cu2O coated glassy carbon electrode and 182.9 ± 8.83% µA mM−1 cm−2 on Cu2O coated graphene printed electrodes, making them a strong candidate for future portable, non-invasive glucose monitoring devices on biodegradable substrates. For portable applications we demonstrated the sensor on artificial sweat in 0.1 M NaOH solution, indicating the Cu2O nanocluster is selective to glucose from 0.0 to +0.6 V even in the presence of common interference such as urea and NaCl.

This review details the current literature on relevant aspects of biofilm formation and microbial control in dental practice. To date, there is no published evidence of a serious public health risk from biofilm-contaminated dental waterlines. However, there remain few effective methods of decontamination of such waterlines.