Search results for "silver nanoparticles"

PROPERTIES AND APPLICATIONS OF POLYAMINOCYCLODEXTRIN DERIVATIVES

Nel presente lavoro sono state prese in esame le potenziali applicazioni delle poliamminociclodestrine. In particolare, diversi derivati poliamminociclodestrinici (amCD) sono stati ottenuti utilizzando un approccio sintetico diretto, tramite reazione di sostituzione nucleofila tra la heptakis-(6-deossi)-(6-bromo)-βCD (BrβCD) e poliammine lineari. Una volta effettuata l’opportuna caratterizzazione NMR, ESI-MS e potenziometrica, sono state investigate diverse possibili utilizzazioni di tali materiali. Anzitutto, sono state valutate le capacità di dare complessi di inclusione host-guest con diversi derivati organici sia delle amCD libere che di materiali costituiti da nanospugne a base di amCD…

Photochemical preparation of polyaminocyclodextrin-capped silver nanocomposites: mechanistic insights

2016

Photoreduction of silver salts in the presence of three polyaminocyclodextrin derivatives (AmCD, Figure 1) constitutes a simple and straightforward route to obtain stable Ag nanoparticles. These systems have been suitably characterized (UV-vis, FT-IR, TEM, Figure 2) and tested for their antimicrobial activity.1 We observed that Ag photoreduction is effectively induced by irradiation with green light (513 nm); however, best performances are achieved with the use of a light source having at the same time a significant emission in the near-infrared (NIR) region. On the grounds of analytical and kinetic evidences, we hypothesized a multi-step mechanism for nanoparticle formation. In particular,…

Light trapping by plasmonic nanoparticles

2020

Abstract Metallic nanoparticles sustaining localized surface plasmon resonances are of great interest for enhancing light trapping in thin film photovoltaics. In this chapter, we explore the correlation between the structural and optical properties of self-assembled silver nanostructures fabricated by a solid-state dewetting process on various substrates relevant for silicon photovoltaics and later integrated into plasmonic back reflectors. Our study allows us to optimize the performance of nanostructures by identifying the fabrication conditions in which desirable circular and uniformly spaced nanoparticles are obtained. Second, we introduce a novel optoelectronic spectroscopic method that…

Synthesis and characterization of new polyamino-cyclodextrin materials.

2011

With the aim of the synthesis of chemically modified cyclodextrins bearing polyamine pendant groups, potentially useful as capping agents for the preparation of nanosized metal systems or as auxiliaries for gene transfection, the reaction between the heptakis-(6-iodo)-(6-deoxy)-b-cyclodextrin and various polyamines has been explored. This synthetic approach allows obtaining materials constituted by mixtures of cyclodextrins, having different degrees of substitution, which were satisfactorily characterized by means of various complementary techniques (ESI-MS, NMR, potentiometric titration). The products obtained were successfully subjected to preliminary tests for their binding abilities tow…

PROTEOMIC IDENTIFICATION OF NOVEL MARKERS IN BREAST AND COLON CANCER

Background: Discovery of new biomarker represent the greatest promise for the detection and management of cancer. Although progress in cancer biology has been rapid during the past few years, the complete understanding of molecular basis for cancer initiation, progression and efficacious treatments is still lacking. In this context, the application of proteomic strategies is now holding a focal position. The main reason is that proteins are the functional players that drive cancer phenotypes. Among cancers, breast and colon represent the most frequent forms. The evolution of these type of cancer are not easily predictable since there are several types that behave differently among patients.…

Inorganic/organic hybrid nanoparticles synthesized in a two-step radiation-driven process

2022

In this work, we have synthesized inorganic-organic hybrid nanoparticles via radiation synthesis of inorganic nanoparticles (Ag and CeO2) in aqueous dispersions containing radiation-synthesized poly(N-vinyl pyrrolidone) (PVP) nanogels (NG). The experiments show that there are strong interactions between the inorganic precursors (Ag+ and Ce3+) and the nanogel prior to irradiation. The two hybrid systems (Ag/NG and CeO2/NG) were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD confirms the formation of crystalline Ag and CeO2. TEM reveals that the inorganic nanoparticles are evenly distributed in/on the nanogel. Both XRD and TEM show that size of the…

CYTOTOXIC EFFECTS OF SILVER NANOPARTICLES (AgNPs) BIOSYNTHESIZED FROM KLEBSIELLA OXYTOCA DSM29614 AGAINST BREAST CANCER CELLS

2015

Klebsiella oxytoca DSM 29614 (KO) is a strain that produces, under anaerobic conditions, bacterial exopolysaccharides (EPSs), made of four rhamnose (Rha), two glucuronic acids (GlcA) and one galactose (Gal) bound by α and β glycosidic bonds1,2, showing metal-binding properties3. In particular, KO in the presence of AgNO3 is able to synthesize silver nanoparticles (AgNPs) incorporated within the EPS (AgNPs-EPS). The AgNPs-EPS, may contain Ag+1 when KO growing in the presence of oxygen and Ag° under anaerobic conditions, giving a different biological activity4. In the present study were evaluated the cytotoxic effects of AgNPs-EPS, produced under aerobic and anaerobic conditions, on breast ca…

Galvanic deposition of Chitosan-AgNPs as antibacterial coating

Thanks to mechanical properties similar human bones, metallic materials represent the best choice for fabrication of orthopedic implants. Although metals could be widely used in the field of biomedical implants, corrosion phenomena could occur, causing metal ions releasing around periprosthetic tissues leading, in the worst cases, to the development of infections. In these cases, patients need prolonged antibiotic therapies that may cause bacterial resistance. Preventing bacterial colonization of biomedical surfaces is the key to limiting the spread of infections. Antibacterial coatings have become a very active field of research, strongly stimulated by the increasing urgency of identifying…

Synthesis, characterization and antimicrobial activity of polyaminocyclodextrin-capped Ag Nanoparticles

2015

Biocompatible Ag nanocomposites were prepared by photoreduction of ammoniacal silver acetate in the presence of a polyaminocyclodextrin, namely the poly-{6-[3-(2-(3-aminopropylamino)-ethylamino)-propylamino]}-(6-deoxy)-b-CD (amCD, figure 1). The obtained Ag-amCD systems, which possess an oniontype structure [1] with a metal core surrounded by several layers of the capping agent, were characterized by means of various complementary techniques. In particular, FT-IR spectroscopy confirmed the presence of the amCD scaffold in the composite, and evidenced a partial oxidative degradation of the polyamine branches,due to the fact that these groups function as sacrificial reducing agents in the pho…

Developing Antibiofilm Fibrillar Scaffold with Intrinsic Capacity to Produce Silver Nanoparticles

2022

The development of biomedical systems with antimicrobial and antibiofilm properties is a difficult medical task for preventing bacterial adhesion and growth on implanted devices. In this work, a fibrillar scaffold was produced by electrospinning a polymeric organic dispersion of polylactic acid (PLA) and poly(α,β-(N-(3,4-dihydroxyphenethyl)-L-aspartamide-co-α,β-N-(2-hydroxyethyl)-L-aspartamide) (PDAEA). The pendant catechol groups of PDAEA were used to reduce silver ions in situ and produce silver nanoparticles onto the surface of the electrospun fibers through a simple and reproducible procedure. The morphological and physicochemical characterization of the obtained s…