ABSTRACT
Re-designing existing nano-silver technologies to optimize efficacy and sustainability has a tangible impact on preventing infections and limiting the spread of pathogenic microorganisms. Advancements in manufacturing processes could lead to more cost-effective and scalable production methods, making nano-silver-based antimicrobial products more accessible in various applications, such as medical devices, textiles, and water purification systems. In this paper, we present a new, versatile, and eco-friendly one-pot process for preparing silver nanoparticles (AgNPs) at room temperature by using a quaternary ammonium salt of hydroxyethyl cellulose (HEC), a green ingredient, acting as a capping and reducing agent. The resulting nano-hybrid phase, AgHEC, consists of AgNPs embedded into a hydrogel matrix with a tunable viscosity depending on the conversion grade, from ions to nanoparticles, and on the pH. To investigate the synthesis kinetics, we monitored the reaction progress within the first 24 h by analyzing the obtained NPs in terms of particle size (dynamic light scattering (DLS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM)), Z-potential (ELS), surface plasmon resonance (UV-VIS), crystallographic phase (XRD), viscosity, and reaction yield (inductively coupled plasma-optical emission spectrometry (ICP-OES)). To explore the design space associated with AgHEC synthesis, we prepared a set of sample variants by changing two independent key parameters that affect nucleation and growth steps, thereby impacting the physicochemical properties and the investigated antimicrobial activity. One of the identified design alternatives pointed out an improved antimicrobial activity in the suspension, which was confirmed after application as a coating on nonwoven cellulose fabrics. This enhancement was attributed to a lower particle size distribution and a positive synergistic effect with the HEC matrix.
ABSTRACT
Undiagnosed asthma has been poorly studied before adolescence since it can go unnoticed by parents and doctors. Moreover, it is unusual to look for undiagnosed asthma by directly questioning children on the presence of current respiratory symptoms. Epidemiologic studies show that more adolescents quote symptoms suggestive of asthma than the prevalence of doctor-diagnosed asthma, but respiratory symptoms compatible with asthma remain undetected by parents of younger children more frequently than doctors diagnose asthma in their children. We attempted to evaluate the relevance of a questionnaire used since 2011 by school doctors in Paris to detect asthma. In this questionnaire, the family history of atopy and asthma were completed by the parents when they met the school doctor (last year of preschool) and questions on current respiratory symptoms were answered by third-grade children seen alone by the school doctor. One hundred and thirty-one children out of 1135 children questioned had a positive questionnaire for suspected asthma. In three-quarters of the cases, questionnaires were positive based on the children's answers on their respiratory symptoms (without a positive answer on personal or family history being necessary). The outcome of 41 children screened by the questionnaire was known. Twenty (49%) children had received a final diagnosis of asthma, of whom 12 were put on asthma controllers. Among these 20 children, two children underwent lung function testing and two others underwent tests for allergy. In eight children, tests had been requested by the child's GP, but no final diagnosis was reported by the parents. None of the 13 children in whom asthma was ruled out had any test performed. It was concluded that it is possible to detect undiagnosed asthma in children as young as 8 years by directly asking them about their respiratory symptoms. The knowledge of personal and family history can improve screening for asthma in these children. A more thorough evaluation of all children with a positive questionnaire is necessary to better understand the properties of the questionnaire. Finally, the best way to implement this screening program remains to be established (school health, GPs).