Enhanced stability of organic field-effect transistor biosensors bearing electrosynthesized ZnO nanoparticles

Herein electrosynthesized ZnO nanoparticles (ZnO NPs) agents to largely improve functional bio-interlayer organic field-effect transistor (FBI-OFET) biosensors stability are investigated. For a proof-of-principle, streptavidin (SA) was chosen as the capturing biomolecule to sense biotin and poly-3-hexylthiophene (P3HT) served as channel material. The ZnO NPs were prepared and integrated into the FBI-OFET architecture by means of a straightforward and versatile procedure. To this end, ZnO NPs were mixed with an SA solution and the resulting aqueous suspension was readily spin-coated onto the SiO2gate dielectric. The P3HT film was spin-coated on the SA-ZnO NPs layer afterwards with the whole fabrication procedure taking no more than 30 min. The FBI-OFET biosensors bearing the ZnO NPs exhibited a shelf life exceeding one year, while the bare ones failed to work after few weeks. Moreover, the ZnO NPs enabled a two orders of magnitude increase in field-effect mobility while the already proven very good sensing performances were retained. The electrical and XPS characterization of the ZnO NPs based functional bio-interlayer provided information about the role of the nanostructured oxide on the improved device stability and a plausible mechanism for this occurrence is derived accordingly

A Review on Montmorillonite-Based Nanoantimicrobials: State of the Art

One of the crucial challenges of our time is to effectively use metal and metal oxide nanoparticles (NPs) as an alternative way to combat drug-resistant infections. Metal and metal oxide NPs such as Ag, Ag2O, Cu, Cu2O, CuO, and ZnO have found their way against antimicrobial resistance. However, they also suffer from several limitations ranging from toxicity issues to resistance mechanisms by complex structures of bacterial communities, so-called biofilms. In this regard, scientists are urgently looking for convenient approaches to develop heterostructure synergistic nanocomposites which could overcome toxicity issues, enhance antimicrobial activity, improve thermal and mechanical stability, and increase shelf life. These nanocomposites provide a controlled release of bioactive substances into the surrounding medium, are cost effective, reproducible, and scalable for real life applications such as food additives, nanoantimicrobial coating in food technology, food preservation, optical limiters, the bio medical field, and wastewater treatment application. Naturally abundant and non-toxic Montmorillonite (MMT) is a novel support to accommodate NPs, due to its negative surface charge and control release of NPs and ions. At the time of this review, around 250 articles have been published focusing on the incorporation of Ag-, Cu-, and ZnO-based NPs into MMT support and thus furthering their introduction into polymer matrix composites dominantly used for antimicrobial application. Therefore, it is highly relevant to report a comprehensive review of Ag-, Cu-, and ZnO-modified MMT. This review provides a comprehensive overview of MMT-based nanoantimicrobials, particularly dealing with preparation methods, materials characterization, and mechanisms of action, antimicrobial activity on different bacterial strains, real life applications, and environmental and toxicity issues

The Pros and Cons of the Use of Laser Ablation Synthesis for the Production of Silver Nano-Antimicrobials

Silver nanoparticles (AgNPs) are well-known for their antimicrobial effects and several groups are proposing them as active agents to fight antimicrobial resistance. A wide variety of methods is available for nanoparticle synthesis, affording a broad spectrum of chemical and physical properties. In this work, we report on AgNPs produced by laser ablation synthesis in solution (LASiS), discussing the major features of this approach. Laser ablation synthesis is one of the best candidates, as compared to wet-chemical syntheses, for preparing Ag nano-antimicrobials. In fact, this method allows the preparation of stable Ag colloids in pure solvents without using either capping and stabilizing agents or reductants. LASiS produces AgNPs, which can be more suitable for medical and food-related applications where it is important to use non-toxic chemicals and materials for humans. In addition, laser ablation allows for achieving nanoparticles with different properties according to experimental laser parameters, thus influencing antibacterial mechanisms. However, the concentration obtained by laser-generated AgNP colloids is often low, and it is hard to implement them on an industrial scale. To obtain interesting concentrations for final applications, it is necessary to exploit high-energy lasers, which are quite expensive. In this review, we discuss the pros and cons of the use of laser ablation synthesis for the production of Ag antimicrobial colloids, taking into account applications in the food packaging field

Can Nanotechnology and Materials Science Help the Fight against SARS-CoV-2?

Since 2004, we have been developing nanomaterials with antimicrobial properties, the so-called nanoantimicrobials. When the coronavirus disease 2019 (COVID-19) emerged, we started investigating new and challenging routes to nanoantivirals. The two fields have some important points of contact. We would like to share with the readership our vision of the role a (nano)materials scientist can play in the fight against the COVID-19 pandemic. As researchers specifically working on surfaces and nanomaterials, in this letter we underline the importance of nanomaterial-based technological solutions in several aspects of the fight against the virus. While great resources are understandably being dedicated to treatment and diagnosis, more efforts could be dedicated to limit the virus spread. Increasing the efficacy of personal protection equipment, developing synergistic antiviral coatings, are only two of the cases discussed. This is not the first nor the last pandemic: our nanomaterials community may offer several technological solutions to challenge the ongoing and future global health emergencies. Readers’ feedback and suggestions are warmly encouraged

A New Nanocomposite Packaging Based on LASiS-Generated AgNPs for the Preservation of Apple Juice

Designing bioactive materials, with controlled metal ion release, exerting a significant biological action and associated to low toxicity for humans, is nowadays one of the most important challenges for our community. The most looked-for nanoantimicrobials are capable of releasing metal species with defined kinetic profiles, either by slowing down or inhibiting bacterial growth and pathogenic microorganism diffusion. In this study, laser ablation synthesis in solution (LASiS) has been used to produce bioactive Ag-based nanocolloids, in isopropyl alcohol, which can be used as water-insoluble nano-reservoirs in composite materials like poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Infrared spectroscopy was used to evaluate the chemical state of pristine polymer and final composite material, thus providing useful information about synthesis processes, as well as storage and processing conditions. Transmission electron microscopy was exploited to study the morphology of nano-colloids, along with UV-Vis for bulk chemical characterization, highlighting the presence of spheroidal particles with average diameter around 12 nm. Electro-thermal atomic absorption spectroscopy was used to investigate metal ion release from Ag-modified products, showing a maximum release around 60 ppb, which ensures an efficient antimicrobial activity, being much lower than what recommended by health institutions. Analytical spectroscopy results were matched with bioactivity tests carried out on target microorganisms of food spoilage

Italian Soft Days 2022

Italian Soft Days (iSoDays) is a series of meetings aimed at gathering scientists interested in soft condensed matter science, a broad interdisciplinary community including physicists, chemists, biologists, materials scientists, mathematicians, and engineers. With iSoDays we would like to provide to all the scientists orbiting around the Italian soft matter community a periodic opportunity for meeting, exchanging ideas, getting informed about the most recent developments, reinforcing their collaboration networks and designing new paths for collaborative research

Recent advances in the synthesis and characterization of nano-antimicrobials

The application of metals and metal oxides in the form of nanostructured antimicrobials is continuously expanding. In the last decades, especially Cu-, ZnO- and Ag-based nano-antimicrobials have attracted the interest of scientists and technologists, as assessed by the huge amount of reports on the synthesis and characterization of nanosized bioactive materials. In fact, despite numerous and strong antibiotics nowadays available, infections caused by antimicrobial resistant bacteria are still a major cause of morbidity and mortality. Consequently, attention has been devoted to the development of nanoparticlebased antimicrobial agents: several classes of antimicrobial nanoparticles (NPs) and nanosized carriers for antibiotics delivery have proven their effectiveness for treating infectious diseases, including antibiotic resistant ones, in vitro as well as in animal models. The present review discusses the recent advances in synthesis, characterization, and application of Cu-, ZnO-, and Ag-based nano-antimicrobials, along with a brief mention of nanotoxicology issues

Recent advances on the spectroscopic characterization of microbial biofilms: A critical review

Biofilms are a major cause of health and environmental issues. Bacteria organized in biofilms are much more resistant to biocides than their equivalents in the planktonic state. In this context, spectroscopic techniques have significantly contributed to a more fundamental understanding of biofilm formation, which is crucial to prevent and limit their generation, spreading, and maturation. In this review, recent progress on the main analytical approaches enabling the spectroscopic characterization of microbial biofilms is comparatively discussed. In addition, less commonly used techniques, facilitating biofilm studies, will be also presented. Advantages and drawbacks of each discussed technique will be underlined, thus providing an overview on spectroscopic approaches for studying biofilms