Publications by authors named "Lucia Petti"

17 Publications

  • Page 1 of 1

Plasmonic Metasurfaces Based on Pyramidal Nanoholes for High-Efficiency SERS Biosensing.

ACS Appl Mater Interfaces 2021 Sep 1;13(36):43715-43725. Epub 2021 Sep 1.

Institute of Applied Sciences and Intelligent Systems "E. Caianiello" CNR, 80078 Pozzuoli, Italy.

An inverted pyramidal metasurface was designed, fabricated, and studied at the nanoscale level for the development of a label-free pathogen detection on a chip platform that merges nanotechnology and surface-enhanced Raman scattering (SERS). Based on the integration and synergy of these ingredients, a virus immunoassay was proposed as a relevant proof of concept for very sensitive detection of hepatitis A virus, for the first time to our best knowledge, in a very small volume (2 μL), without complex signal amplification, allowing to detect a minimal virus concentration of 13 pg/mL. The proposed work aims to develop a high-flux and high-accuracy surface-enhanced Raman spectroscopy (SERS) nanobiosensor for the detection of pathogens to provide an effective method for early and easy water monitoring, which can be fast and convenient.
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http://dx.doi.org/10.1021/acsami.1c12525DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8447193PMC
September 2021

SERS Biosensor Based on Engineered 2D-Aperiodic Nanostructure for In-Situ Detection of Viable Bacterium in Complex Matrix.

Nanomaterials (Basel) 2021 Mar 31;11(4). Epub 2021 Mar 31.

Institute of Applied Sciences and Intelligent Systems "E. Caianiello" of CNR, 80078 Pozzuoli, Italy.

is a foodborne pathogen globally affecting both the economy and healthcare. Surface Enhanced Raman Spectroscopy (SERS) nano-biosensing can be a promising strategy for its detection. We combined high-performance quasi-crystal patterned nanocavities for Raman enhancement with the use of covalently immobilized Tbilisi bacteriophages as high-performing bio-receptors. We coupled our efficient SERS nano-biosensor to a Raman system to develop an on-field phage-based bio-sensing platform capable of monitoring the target bacteria. The developed biosensor allowed us to identify in milk by our portable SERS device. Upon bacterial capture from samples (10 cells), a signal related to the pathogen recognition was observed, proving the concrete applicability of our system for on-site and in-food detection.
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http://dx.doi.org/10.3390/nano11040886DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8067257PMC
March 2021

Irreversible accumulated SERS behavior of the molecule-linked silver and silver-doped titanium dioxide hybrid system.

Nat Commun 2020 04 14;11(1):1785. Epub 2020 Apr 14.

Institute of Applied Sciences and Intelligent Systems-ISASI, CNR, Via Campi Flegrei, 34, 80078 Pozzuoli, Napoli, Italy.

In recent years, surface-enhanced Raman scattering (SERS) of a molecule/metal-semiconductor hybrid system has attracted considerable interest and regarded as the synergetic contribution of the electromagnetic and chemical enhancements from the incorporation of noble metal into semiconductor nanomaterials. However, the underlying mechanism is still to be revealed in detail. Herein, we report an irreversible accumulated SERS behavior induced by near-infrared (NIR) light irradiating on a 4-mercaptobenzoic acid linked with silver and silver-doped titanium dioxide (4MBA/Ag/Ag-doped TiO) hybrid system. With increasing irradiation time, the SERS intensity of 4MBA shows an irreversible exponential increase, and the Raman signal of the Ag/Ag-doped TiO substrate displays an exponential decrease. A microscopic understanding of the time-dependent SERS behavior is derived based on the microanalysis of the Ag/Ag-doped TiO nanostructure and the molecular dynamics, which is attributed to three factors: (1) higher crystallinity of Ag/Ag-doped TiO substrate; (2) photo-induced charge transfer; (3) charge-induced molecular reorientation.
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http://dx.doi.org/10.1038/s41467-020-15484-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7156739PMC
April 2020

Large oncosomes overexpressing integrin alpha-V promote prostate cancer adhesion and invasion via AKT activation.

J Exp Clin Cancer Res 2019 Jul 18;38(1):317. Epub 2019 Jul 18.

Experimental Pharmacology Unit, Istituto Nazionale Tumori - IRCCS- Fondazione G. Pascale, Via M. Semmola, 80131, Naples, Italy.

Background: Molecular markers for prostate cancer (PCa) are required to improve the early definition of patient outcomes. Atypically large extracellular vesicles (EVs), referred as "Large Oncosomes" (LO), have been identified in highly migratory and invasive PCa cells. We recently developed and characterized the DU145R80 subline, selected from parental DU145 cells as resistant to inhibitors of mevalonate pathway. DU145R80 showed different proteomic profile compared to parental DU145 cells, along with altered cytoskeleton dynamics and a more aggressive phenotype.

Methods: Immunofluorescence staining and western blotting were used to identify blebbing and EVs protein cargo. EVs, purified by gradient ultra-centrifugations, were analyzed by tunable resistive pulse sensing and multi-parametric flow cytometry approach coupled with high-resolution imaging technologies. LO functional effects were tested in vitro by adhesion and invasion assays and in vivo xenograft model in nude mice. Xenograft and patient tumor tissues were analyzed by immunohistochemistry.

Results: We found spontaneous blebbing and increased shedding of LO from DU145R80 compared to DU145 cells. LO from DU145R80, compared to those from DU145, carried increased amounts of key-molecules involved in PCa progression including integrin alpha V (αV-integrin). By incubating DU145 cells with DU145R80-derived LO we demonstrated that αV-integrin on LO surface was functionally involved in the increased adhesion and invasion of recipient cells, via AKT. Indeed either the pre-incubation of LO with an αV-integrin blocking antibody, or a specific AKT inhibition in recipient cells are able to revert the LO-induced functional effects. Moreover, DU145R80-derived LO also increased DU145 tumor engraftment in a mice model. Finally, we identified αV-integrin positive LO-like structures in tumor xenografts as well as in PCa patient tissues. Increased αV-integrin tumor expression correlated with high Gleason score and lymph node status.

Conclusions: Overall, this study is the first to demonstrate the critical role of αV-integrin positive LO in PCa aggressive features, adding new insights in biological function of these large EVs and suggesting their potential use as PCa prognostic markers.
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http://dx.doi.org/10.1186/s13046-019-1317-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6639931PMC
July 2019

SERS-based cascade amplification bioassay protocol of miRNA-21 by using sandwich structure with biotin-streptavidin system.

Analyst 2019 Feb;144(5):1741-1750

Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 315211, Zhejiang, China.

In our bioassay protocol, the [email protected]@DNA-biotin probes were synthesized by linking biotin-modified DNA and 4-mercaptobenzoic acid-covered Ag nanoparticles, and the [email protected]@anti-digoxin/digoxin-DNA substrate was fabricated by immune linking of digoxin-DNA and anti-digoxin immobilized on a Ag-coated wafer. Then, the probes, miRNA-21 and the substrate were constructed into a "sandwich structure" to detect the variation in the SERS signals with respect to miRNA-21 concentrations. Next, streptavidin and extra probes were alternately introduced to implement the cascade amplification of the SERS signal to increase the detection sensitivity. The results show that the limit of detection (LOD) with cascade amplification is remarkably improved from 97.81 pM to 38.02 fM, which is three orders of magnitude higher than the original data without cascade amplification. Furthermore, the SERS-based cascade amplification mechanism was analyzed and is attributed to the "hot spots effect" of the noble metal nanostructure. The biotin-streptavidin (B-S) system was introduced into the SERS detection platform, and the novel SERS-based cascade amplification bioassay protocol has significant creativity for the detection of nucleic acids.
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http://dx.doi.org/10.1039/c8an02259cDOI Listing
February 2019

Classification analyses for prostate cancer, benign prostate hyperplasia and healthy subjects by SERS-based immunoassay of multiple tumour markers.

Talanta 2018 Oct 23;188:238-244. Epub 2018 May 23.

Affiliated Hospital, School of Medicine, Ningbo University, Ningbo 315020, Zhejiang, China.

Prostate cancer (PCa) is a leading cause of cancer-related death among males globally. To date, prostate-specific antigen (PSA), as a typical tumour marker, has been widely used in the early diagnosis of PCa. However, in practical clinical tests, high serum levels of PSA show a high probability for false-positive results, leading to misdiagnoses. In this study, we developed a new classification system for PCa, benign prostate hyperplasia (BPH) and healthy subjects by using a surface-enhanced Raman scattering (SERS)-based immunoassay of multiple tumour markers along with a support vector machine (SVM) algorithm. Silver nanoparticles (AgNPs) as immune probes and [email protected]@Ag-NPs SERS as immune substrates were constructed into a sandwich structure to serve as an ultrasensitive SERS-based immunoassay platform of tumour markers. With this assay, the limits of detection for PSA, prostate-specific membrane antigen (PSMA) and human kallikrein 2 (hK2) were as low as 0.46 fg mL, 1.05 fg mL and 0.67 fg mL, respectively. Furthermore, the serum levels of PSA, PSMA and hK2 in clinical samples were successfully detected using the SERS-based immunoassay platform, and correct classifications of PCa, BPH and healthy subjects were feasible with help of the linear SVM algorithm. These results demonstrate the potential for improving the diagnostic accuracy of PCa. Overall, the linear SVM classification model with multiple tumour markers exhibited good classifications of PCa, BPH and healthy subjects, with a PCa diagnostic accuracy of 70% that was significantly superior to that of the linear SVM classification model based only on the serum level of PSA (50%). Therefore, combining the SERS-based immunoassay with pattern recognition technology can allow for comprehensive analyses of the serum levels of multiple tumour markers to effectively improve the diagnostic accuracy of cancer with potential applications in point-of-care testing.
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http://dx.doi.org/10.1016/j.talanta.2018.05.070DOI Listing
October 2018

Extraordinary Effects in Quasi-Periodic Gold Nanocavities: Enhanced Transmission and Polarization Control of Cavity Modes.

ACS Nano 2018 01 26;12(1):504-512. Epub 2017 Dec 26.

Department of Physics, University of Calabria and CNR Nanotec , S. S. di Cosenza, 87036 Rende, Italy.

Plasmonic quasi-periodic structures are well-known to exhibit several surprising phenomena with respect to their periodic counterparts, due to their long-range order and higher rotational symmetry. Thanks to their specific geometrical arrangement, plasmonic quasi-crystals offer unique possibilities in tailoring the coupling and propagation of surface plasmons through their lattice, a scenario in which a plethora of fascinating phenomena can take place. In this paper we investigate the extraordinary transmission phenomenon occurring in specifically patterned Thue-Morse nanocavities, demonstrating noticeable enhanced transmission, directly revealed by near-field optical experiments, performed by means of a scanning near-field optical microscope (SNOM). SNOM further provides an intuitive picture of confined plasmon modes inside the nanocavities and confirms that localization of plasmon modes is based on size and depth of nanocavities, while cross talk between close cavities via propagating plasmons holds the polarization response of patterned quasi-crystals. Our performed numerical simulations are in good agreement with the experimental results. Thus, the control on cavity size and incident polarization can be used to alter the intensity and spatial properties of confined cavity modes in such structures, which can be exploited in order to design a plasmonic device with customized optical properties and desired functionalities, to be used for several applications in quantum plasmonics.
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http://dx.doi.org/10.1021/acsnano.7b07076DOI Listing
January 2018

Octupolar Metastructures for a Highly Sensitive, Rapid, and Reproducible Phage-Based Detection of Bacterial Pathogens by Surface-Enhanced Raman Scattering.

ACS Sens 2017 Jul 20;2(7):947-954. Epub 2017 Jun 20.

Institute of Applied Sciences and Intelligent Systems "E. Caianiello" of CNR , 80072 Pozzuoli, Italy.

The development of fast and ultrasensitive methods to detect bacterial pathogens at low concentrations is of high relevance for human and animal health care and diagnostics. In this context, surface-enhanced Raman scattering (SERS) offers the promise of a simplified, rapid, and high-sensitive detection of biomolecular interactions with several advantages over previous assay methodologies. In this work, we have conceived reproducible SERS nanosensors based on tailored multilayer octupolar nanostructures which can combine high enhancement factor and remarkable molecular selectivity. We show that coating novel multilayer octupolar metastructures with proper self-assembled monolayer (SAM) and immobilized phages can provide label-free analysis of pathogenic bacteria via SERS leading to a giant increase in SERS enhancement. The strong relative intensity changes of about 2100% at the maximum scattered SERS wavelength, induced by the Brucella bacterium captured, demonstrate the performance advantages of the bacteriophage sensing scheme. We performed measurements at the single-cell level thus allowing fast identification in less than an hour without any demanding sample preparation process. Our results based on designing well-controlled octupolar coupling platforms open up new opportunities toward the use of bacteriophages as recognition elements for the creation of SERS-based multifunctional biochips for rapid culture and label-free detection of bacteria.
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http://dx.doi.org/10.1021/acssensors.7b00195DOI Listing
July 2017

An Unconventional Approach to Photomobile Composite Polymer Films.

Adv Mater 2017 Apr 1;29(13). Epub 2017 Feb 1.

Dipartimento SIMAU, Università Politecnica delle Marche, Via Brecce Bianche, 60131, Ancona, AN, Italy.

Photomobile polymer (Pmp) films are fabricated by using a cheap and fast process. The working mechanism of the Pmp-film motion under illumination is explained. Details concerning the film structure and formation are given. Two related applications regarding light-induced caterpillar-miming motion and photocontrolled electrical switches are proposed.
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http://dx.doi.org/10.1002/adma.201604800DOI Listing
April 2017

[email protected] core-shell nanocubes: epitaxial growth synthesis and surface-enhanced Raman scattering performance.

Phys Chem Chem Phys 2015 Mar;17(10):6819-26

Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 31 5211, Zhejiang, China.

Novel [email protected] core-shell nanocubes (NCs) were successfully prepared by the controlled epitaxial growth of Ag shells onto Au nanoellipsoids (NEs) in the presence of surfactants. The growth mechanism of the [email protected] core-shell NCs was systematically investigated by analyzing their morphology, optical properties, and crystallography. The localized surface plasmon resonance (LSPR) characteristics and the electric field distribution of the [email protected] core-shell NCs were studied using the finite element method (FEM) based on the plasmon hybridization theory. Compared with pure Ag NCs, the absorption spectrum of the [email protected] core-shell NCs exhibits a red shift and a weak shoulder near 550 nm, and the notable enhancement of electric field occurs around the corners along the long-axis of the Au ellipsoidal core because of plasmonic resonant coupling. Surface-enhanced Raman scattering (SERS) of the [email protected] core-shell NCs labeled with 4-mercaptobenzoic acid molecules reveals that the bimetallic core-shell NCs possess efficient SERS activity with an enhancement factor EF = 2.27 × 10(6), thus confirming the possibility of using the [email protected] core-shell NCs as a stable probe for SERS-based biosensing applications.
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http://dx.doi.org/10.1039/c4cp05642fDOI Listing
March 2015

Controllable synthesis and SERS characteristics of hollow sea-urchin gold nanoparticles.

Phys Chem Chem Phys 2014 Dec 29;16(46):25601-8. Epub 2014 Oct 29.

Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 315211, Zhejiang, China.

Hollow sea-urchin gold nanoparticles (HSU-GNPs) were successfully prepared through a novel one-step galvanic replacement strategy, and their corresponding optical properties was studied in detail. During the synthesis process, the sizes of the interior hollows of the HSU-GNPs could be changed by adjusting the amount of silver nitrate added into hydrogen tetrachloroaurate trihydrate solution. The absorption spectra of the HSU-GNPs showed that the localized surface plasmon resonance (LSPR) peaks were red-shifted with increasing size of the interior hollows in the HSU-GNPs. When the added amount of silver nitrate was up to 6 μl, the LSPR peak of the synthesized HSU-GNP reached 726 nm as a maximum red-shift. Furthermore, the absorption spectra of the HSU-GNPs with different morphologies were theoretically simulated by the finite element method, which was consistent with the experimental results and explained the origin of the red-shift of the LSPR peaks. In addition, the surface-enhanced Raman scattering (SERS) of the sea urchin gold nanoparticles were also investigated using 4-mercaptobenzoic acid as a Raman reporter molecule. Both the experimental and calculated results showed that the HSU-GNPs had stronger SERS enhancement than the solid sea-urchin gold nanoparticles. In particular, the HSU-GNPs prepared by adding 6 μl silver nitrate exhibited a maximum SERS enhancement factor, EF = 1.1 × 10(9), due to the LSPR peak at 726 nm which is near to the excitation wavelength, 785 nm. This feature is significant for designing a biosensor with a super-high sensitivity based on the morphology of the HSU-GNPs.
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http://dx.doi.org/10.1039/c4cp04017aDOI Listing
December 2014

Localized surface plasmon resonance and surface enhanced Raman scattering responses of [email protected] core-shell nanorods with different thickness of Ag shell.

J Nanosci Nanotechnol 2014 Jun;14(6):4245-50

The properties of the localized surface plasmon resonance (LSPR) and the surface enhanced Raman scattering (SERS) of the core-shell bimetallic nanostructures, that is the monodisperse [email protected] core-shell nanorods with different thickness of Ag shell, are theoretically and experimental researched. The UV-vis-NIR absorption spectra of the [email protected] core-shell nanorods are measured and displayed their blue-shifts of the longitudinal plasmon resonance peaks with increasing of Ag concentrations in the colloidal solution. And the absorption spectra of the [email protected] core-shell nanorods are simulated by the Finite Element Method (FEM), which are in agreement with the experimental measurements and reveal their LSPR mechanism as the varying structures. In addition, Rhodamine 6G, as a Raman reporter molecule, is used to investigate SERS of gold nanorods and [email protected] core-shell nanorods. It is found that [email protected] core-shell nanorods have better SERS responses, comparing with those of Au nanorods, and their SERS intensities are increased with the increases of the Ag shell thickness, which demonstrate that the chemisorptive bond effect and the morphology of the nanoparticle play key roles to the SERS signals. It is significant to design the biosensor based on the properties of [email protected] core-shell nanorods.
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http://dx.doi.org/10.1166/jnn.2014.8202DOI Listing
June 2014

Highly sensitive immunoassay based on SERS using nano-Au immune probes and a nano-Ag immune substrate.

Talanta 2014 Jun 14;123:161-8. Epub 2014 Feb 14.

Institute of Cybernetics "E. Caianiello" of CNR, Via Campi Flegrei 34, 80072 Pozzuoli, Italy.

A super-high-sensitivity immunoassay based on surface-enhanced Raman scattering (SERS) was implemented using the nano-Au immune probes and nano-Ag immune substrate. Ultraviolet-visible extinction spectra, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images, and SERS spectra were used to characterise the nano-Au immune probes and the nano-Ag immune substrate. The nano-Ag immune substrate was prepared by the in situ growth of Ag nanoparticles and the subsequent linkage of these nanoparticles with anti-apolipoprotein B on a silicon wafer. The nano-Ag immune substrate exhibited strong SERS activity, excellent reproducibility, and high biospecificity. The nano-Au immune probes were prepared by immobilising 4-mercaptobenzoic acid (4MBA) molecules as a Raman reporter and anti-apolipoprotein B onto the surfaces of Au nanoparticles. It was found that 4MBA induced the aggregation of Au nanoparticles, resulting in the generation of vast hot spots. Moreover, the nano-Au immune probes exhibited strong SERS activity and high biospecificity. A sandwich-type immunoassay structure consisting of the nano-Au immune probes and nano-Ag immune substrate was used to detect the concentration of apolipoprotein B, where the detection limit was as low as 2 fg/mL (3.878×10(-18) mol/L). Taken together, the experimental results indicate that the proposed immunoassay protocol has a great potential application in biological sensing and clinical diagnostics.
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http://dx.doi.org/10.1016/j.talanta.2014.02.015DOI Listing
June 2014

Novel organic LED structures based on a highly conductive polymeric photonic crystal electrode.

Nanotechnology 2013 Aug 15;24(31):315206. Epub 2013 Jul 15.

Cybernetics Institute of CNR, Pozzuoli, Italy.

In this work we demonstrate the possibility to realize a novel unconventional ITO-free organic light emitting diode (OLED) utilizing a photonic polymeric electrode. Combining electron beam lithography and a plasma etching process to partially structure the highly conductive poly(3,4 ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) it is possible to realize an embedded photonic crystal (PC) structure. The realized PC-anode drastically reduces the light trapped in the OLED, demonstrating the possibility to eliminate further process stages and making it easier to use this technology even on rollable and flexible substrates.
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http://dx.doi.org/10.1088/0957-4484/24/31/315206DOI Listing
August 2013

Fabrication of novel two-dimensional nanopatterned conductive PEDOT:PSS films for organic optoelectronic applications.

ACS Appl Mater Interfaces 2013 Jun 15;5(11):4777-82. Epub 2013 May 15.

Cybernetics Institute of CNR, 80072 Pozzuoli, Italy.

This paper presents a novel strategy to fabricate two-dimensional poly(3,4 ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) photonic crystals (PCs) combining electron beam lithography (EBL) and plasma etching (PE) processes. The surface morphology of PEDOT:PSS PCs after mild oxygen plasma treatment was investigated by scanning electron microscopy. The effects on light extraction are studied experimentally. Vertical extraction of light was found to be strongly dependent on the geometric parameters of the PCs. By changing the lattice type from triangular to square and the geometrical parameters of the photonic structures, the resonance peak could be tuned from a narrow blue emission at 445 nm up to a green emission at 525 nm with a full width at half-maximum of 20 nm, which is in good agreement with Bragg's diffraction theory and free photon band structure. Both finite-difference time-domain and plane wave expansion methods are used to calculate the resonant frequencies and the photonic band structures in the two-dimensional photonic crystals showing a very good agreement with the experiment results. A 2D nanopatterned transparent anode was also fabricated onto a flexible polyethylene terephthalate (PET) substrate and it was integrated into an organic light-emitting diode (OLED). The obtained results fully confirm the feasibility of the developed process of micro/nano patterning PEDOT:PSS. Engineered polymer electrodes prepared by this unique method are useful in a wide variety of high-performance flexible organic optoelectronics.
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http://dx.doi.org/10.1021/am401451rDOI Listing
June 2013

Bragg extraction of light in 2D photonic Thue-Morse quasicrystals patterned in active CdSe/CdS nanorod-polymer nanocomposites.

Nanoscale 2013 Jan 20;5(1):331-6. Epub 2012 Nov 20.

Institute of Cybernetics E. Caianiello of CNR, Via Campi Flegrei 34, 80072 Pozzuoli, Italy.

In this paper two-dimensional (2D) photonic Thue-Morse quasicrystals (ThMo-PQCs) in active CdSe/CdS nanorod (NR) doped polymer nanocomposites are proposed and experimentally demonstrated. Active PQCs and undoped lattices have been prepared in a one-step fabrication process by an electron beam lithography technique (EBL) and the effects on light extraction and emission directionality are studied experimentally. Vertical extraction of light was found to be strongly dependent on both the geometric parameters of the ThMo-PQCs and the presence of NR dopants. By changing the geometrical parameters of the photonic structures, the resonance peak could be tuned from a narrow bluish green emission at 543 nm up to a red-NIR emission at 711 nm with a full width at half-maximum of 22 nm which is in good agreement with Bragg's diffraction theory and free photon band structure. Angular resolved measurements revealed a directional profile in the far-field distribution with guided mode extraction in both doped and undoped PQCs and an enhancement as high as 6.5-fold in light extraction was achieved in the doped photonic structures. These experimental results indicate the critical role of the CdSe/CdS NRs in improving the light extraction efficiency of 2D ThMo-PQCs for solid-state lighting and lasing.
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http://dx.doi.org/10.1039/c2nr31839cDOI Listing
January 2013

Novel hybrid organic/inorganic 2D quasiperiodic PC: from diffraction pattern to vertical light extraction.

Nanoscale Res Lett 2011 May 4;6(1):371. Epub 2011 May 4.

Institute of Cybernetics "E, Caianiello" of CNR, Via Campi Flegrei 34, 80072 Pozzuoli, Italy.

Recently, important efforts have been dedicated to the realization of a fascinating class of new photonic materials or metamaterials, known as photonic quasicrystals (PQCs), in which the lack of the translational symmetry is compensated by rotational symmetries not achievable by the conventional periodic crystals. As ever, more advanced functionality is demanded and one strategy is the introduction of non-linear and/or active functionality in photonic materials. In this view, core/shell nanorods (NRs) are a promising active material for light-emitting applications. In this article a two-dimensional (2D) hybrid a 2D octagonal PQC which consists of air rods in an organic/inorganic nanocomposite is proposed and experimentally demonstrated. The nanocomposite was prepared by incorporating CdSe/CdS core/shell NRs into a polymer matrix. The PQC was realized by electron beam lithography (EBL) technique. Scanning electron microscopy, far field diffraction and spectra measurements are used to characterize the experimental structure. The vertical extraction of the light, by the coupling of the modes guided by the PQC slab to the free radiation via Bragg scattering, consists of a narrow red emissions band at 690 nm with a full width at half-maximum (FWHM) of 21.5 nm. The original characteristics of hybrid materials based on polymers and colloidal NRs, able to combine the unique optical properties of the inorganic moiety with the processability of the host matrix, are extremely appealing in view of their technological impact on the development of new high performing optical devices such as organic light-emitting diodes, ultra-low threshold lasers, and non-linear devices.PACS: 81.07.Pr Organic-inorganic hybrid nanostructures, 81.16.-c Methods of nanofabrication and processing, 42.70.Qs Photonic band-gap materials.
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http://dx.doi.org/10.1186/1556-276X-6-371DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3211462PMC
May 2011
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