In Situ Thermal Generation of Silver Nanoparticles in 3D Printed Polymeric Structures

Polymer nanocomposites have always attracted the interest of researchers and industry because of their potential combination of properties from both the nanofillers and the hosting matrix. Gathering nanomaterials and 3D printing could offer clear advantages and numerous new opportunities in several application fields. Embedding nanofillers in a polymeric matrix could improve the final material properties but usually the printing process gets more difficult. Considering this drawback, in this paper we propose a method to obtain polymer nanocomposites by in situ generation of nanoparticles after the printing process. 3D structures were fabricated through a Digital Light Processing (DLP) system by disolving metal salts in the starting liquid formulation. The 3D fabrication is followed by a thermal treatment in order to induce in situ generation of metal nanoparticles (NPs) in the polymer matrix. Comprehensive studies were systematically performed on the thermo-mechanical characteristics, morphology and electrical properties of the 3D printed nanocomposites

A Facile and Green Microwave-Assisted Strategy to Induce Surface Properties on Complex-Shape Polymeric 3D Printed Structures

Light- induced polymeric 3D printing is becoming a well-established fabrication method, showing manifold advantages such as control of the local chemistry of the manufactured devices. It can be considered a green technology, since the parts are produced when needed and with minimum amount of materials. In this work 3D printing is combined with another green technology, microwave-assisted reaction, to fabricate objects of complex geometry with controllable surface properties, exploiting the presence of remaining functional groups on the surface of 3D printed specimens. In this context, surface functionalization with different amines is studied, optimizing formulations, reaction times, and avoiding surface deterioration. Then, two different applications are investigated. MW-functionalized filter-type structures have been tested against Staphylococcus aureus bacteria, showing high bactericidal activity on the surface along all areas of the complex-shaped structure. Second, a fluidic chip composed of three separated channels is 3D printed, filled with different amine-reactive dyes (dansyl and eosine derivatives), and made to react simultaneously. Complete and independent functionalization of the surface of the three channels is achieved only after 2 min of irradiation. This study demonstrates that light induced 3D printing and microwave-induced chemistry can be used together effectively, and used to produce functional devices

In situ generation of silver nanoparticles in PVDF for the development of resistive switching devices

It is widely accepted that resistive switching devices (RSDs) are extremely appealing as active components in computer memories and logic gates in electronics, directly enabling neuromorphic functionalities. The aim of this study is to investigate the chemical and electrical properties of a nanocomposite polymer, the active component of the device, in order to characterise its composition and behaviour under electric field. This paper presents the morphological and chemical characterization of an in-situ generated silver – Polyvinylidene fluoride-hexafluoropropylene PVDF-HFP nanocomposite (NC) material. A silver salt is added as precursor to the polymer solution and then, after a film casting step, the nanoparticles generation and growth processes are carried out by way of UV irradiation; the growth and the distribution of in-situ generated silver nanoparticles (NPs) in the polymer matrix are described. The devices, built on a planar electrode structure, undergo an I/V test to explore their resistance states at different switching voltages. Furthermore, after electrical analysis a remarkable R off /R on ratio and a relatively low switching voltage (3 V) are achieved, demonstrating the suitability of the developed material for the next generation of soft, wearable, RSDs

Single-Step 3D Printing of Silver-Patterned Polymeric Devices for Bacteria Proliferation Control

This work describes the fabrication of silver-patterned polymeric devices via light-based 3D printing methods from a tailored resin. An acrylate resin containing silver nitrate (AgNO3) as a silver precursor is employed to generate silver nanoparticles (AgNPs) through the in situ reduction of the metallic salt. The silver-based resin is processed through a customized stereolithography SL-3D printing to fabricate structures with silver-patterned surfaces. This customized SL-printer (emitting at 405 nm) offers the possibility of adjusting the machine settings during the printing process allowing for AgNPs to be selectively generated by modifying the laser settings during the 3D printing step. Thus, the resin photopolymerization and the photoinduced formation of AgNPs-based strands can be sequentially achieved during the same printing process with the same light source and using the same printable resin. The fabricated silver-patterned devices exhibit different surface features that might be exploited in systems working in a marine environment to control biofilm proliferation. As a proof-of-concept, the antimicrobial behavior of the silver-based 3D printed device is tested against environmental bacterial mixed communities via UV–vis spectroscopy and evaluating the absorbance change. Further tests, however, would be needed to reinforce the evidence of the bacteria behavior on the silver-patterned 3D printed devices

Chemo- and Thermosensory Responsiveness of Grueneberg Ganglion Neurons Relies on Cyclic Guanosine Monophosphate Signaling Elements

Neurons of the Grueneberg ganglion (GG) in the anterior nasal region of mouse pups respond to cool temperatures and to a small set of odorants. While the thermosensory reactivity appears to be mediated by elements of a cyclic guanosine monophosphate (cGMP) cascade, the molecular mechanisms underlying the odor-induced responses are unclear. Since odor-responsive GG cells are endowed with elements of a cGMP pathway, specifically the transmembrane guanylyl cyclase subtype GC-G and the cyclic nucleotide-gated ion channel CNGA3, the possibility was explored whether these cGMP signaling elements may also be involved in chemosensory GG responses. Experiments with transgenic mice deficient for GC-G or CNGA3 revealed that GG responsiveness to given odorants was significantly diminished in these knockout animals. These findings suggest that a cGMP cascade may be important for both olfactory and thermosensory signaling in the GG. However, in contrast to the thermosensory reactivity, which did not decline over time, the chemosensory response underwent adaptation upon extended stimulation, suggesting that the two transduction processes only partially overlap. Copyright (C) 2011 S. Karger AG, Base

[OP.5C.05] SERUM URIC ACID IS INCREASED IN NORMOTENSIVE OBESE CHILDREN WITH A PARENTAL HYSTORY OF HYPERTENSION

Objective: Increased uric acid levels are closely associated with new-onset hypertension in children, and pilot studies showed that pharmacological lowering of uric acid may reduce blood pressure (BP) in obese pediatric patients. Nevertheless, controversy remains concerning a direct causative role of serum uric acid (SUA) in the pathogenesis of essential hypertension (EH). Our study was aimed to determine if normotensive obese children and adolescent offspring of adults with EH show SUA levels different than those of pediatric subjects in whom there is non family history of EH. Design and method: Fifty-nine obese normotensive children and adolescents, attending for metabolic assessment the Pediatric Diabetes Unit, Children's Hospital "G. Di Cristina", and for cardiovascular evaluation the ESH Hypertension excellence center of the University of Palermo, were studied. All the subjects, aged between 8 and 17 years, underwent routine blood chemistry and oral glucose tolerance test with glucose and insulin determinations. All subjects had blood pressure determinations below the 90th percentile and had no previous history of elevated blood pressure. Results: There were 14 subjects whose parents were both normotensive (FH-), and the remaining 45 subjects whose one or both parents were hypertensive. FH + did not differ regarding age, sex distribution, blood pressure values, body mass index, waist circumference, serum glucose levels when compared to FH-. Among the metabolic parameters assessed, only SUA was significantly higher in FH+ than in FH - (p = 0.007; figure 1)