In Situ SERS Sensing by a Laser-Induced Aggregation of Silver Nanoparticles Templated on a Thermoresponsive Polymer

A stimuli-responsive (pH- and thermoresponsive) micelle-forming diblock copolymer, poly(1,2-butadiene) 290 - block -poly( N , N -dimethylaminoethyl methacrylate) 240 (PB- b -PDMAEMA), was used as a polymer template for the in situ synthesis of silver nanoparticles (AgNPs) through Ag + complexation with PDMAEMA blocks, followed by the reduction of the bound Ag + with sodium borohydride. A successful synthesis of the AgNPs on a PB- b -PDMAEMA micellar template was confirmed by means of UV–Vis spectroscopy and transmission electron microscopy, wherein the shape and size of the AgNPs were determined. A phase transition of the polymer matrix in the AgNPs/PB- b -PDMAEMA metallopolymer hybrids, which results from a collapse and aggregation of PDMAEMA blocks, was manifested by changes in the transmittance of their aqueous solutions as a function of temperature. A SERS reporting probe, 4-mercaptophenylboronic acid (4-MPBA), was used to demonstrate a laser-induced enhancement of the SERS signal observed under constant laser irradiation. The local heating of the AgNPs/PB- b -PDMAEMA sample in the laser spot is thought to be responsible for the triggered SERS effect, which is caused by the approaching of AgNPs and the generation of “hot spots” under a thermo-induced collapse and the aggregation of the PDMAEMA blocks of the polymer matrix. The triggered SERS effect depends on the time of a laser exposure and on the concentration of 4-MPBA. Possible mechanisms of the laser-induced heating for the AgNPs/PB- b -PDMAEMA metallopolymer hybrids are discussed

Linkage between anisotropic and gyrotropic degenerate bandgaps

Formation of bandgaps in a one-dimensional magnetophotonic crystal made of anisotropic uniaxial materials with gyrotropy was studied. In such a crystal two types of degenerate bandgaps can appear at the same frequencies: anisotropic bandgaps (at no magnetization and angularly offset optical axes of the layers\u27 materials) and gyrotropic bandgaps (at magnetization and collinear optical axes). A linkage between such degenerate bandgaps was studied. Abandgap of one type becomes wider if the formation mechanism for the bandgap of the other type is turned on. The width of such a combined bandgap was determined to be a function of only the widths of the respective anisotropic and gyrotropic degenerate bandgaps and to not depend explicitly on any other parameters. ©2011 Optical Society of America

Advantages of laparoscopic management of hydatid cyst of the liver: a Case Report

Scripta Scientifica Medica 2007; 39(2):161-16

Sentinel lymph node mapping in patients with colorectal cancer

BACKGROUND/AIMS: In about 1/3 of the patients with colorectal cancer without metastases which have been radically operated recurrences are observed and these patients die from cancer. This requires improvement of the surgical methods radicality as well as a more accurate determination of the indications for adjuvant chemotherapy administration.The introduction of a method for evaluating the degree of the metastases in colorectal cancer would highlight these issues. To this purpose we apply the method of sentinel mapping.METHODOLOGY: For a period of one year we performed intraoperative sentinel mapping on 103 patients who had been operated for colon or rectal cancer. We used the dying method with Patent Blue V. An algorithm was worked out for sentinel mapping in colorectal cancer.RESULTS: We achieved 100% performance success and 97% sensitivity. We increased the volume of the surgical intervention in 100% of the patients and elevated the clinical stage of 20% of the patients in Ist and IInd stage by means of ultrastaging with immunohistochemistry.CONCLUSIONS: We conclude that sentinel lymph nodes mapping in colorectal cancer is a diagnostic method which is convenient for the surgeons allowing them for an individualized approach toward each patient.Scripta Scientifica Medica 2008;40(1):47-5

Formation of Degenerate Band Gaps in Layered Systems

In the review, peculiarities of spectra of one-dimensional photonic crystals made of anisotropic and/or magnetooptic materials are considered. The attention is focused on band gaps of a special type—the so called degenerate band gaps which are degenerate with respect to polarization. Mechanisms of formation and properties of these band gaps are analyzed. Peculiarities of spectra of photonic crystals that arise due to the linkage between band gaps are discussed. Particularly, it is shown that formation of a frozen mode is caused by linkage between Brillouin and degenerate band gaps. Also, existence of the optical Borrmann effect at the boundaries of degenerate band gaps and optical Tamm states at the frequencies of degenerate band gaps are analyzed

Low-Damage Reactive Ion Etching of Nanoplasmonic Waveguides with Ultrathin Noble Metal Films

Nanoplasmonic waveguides utilizing surface plasmon polaritons (SPPs) propagation have been investigated for more than 15 years and are now well understood. Many researchers make their efforts to find the best ways of using light and overcoming the speed limit of integrated circuits by means of SPPs. Here, we introduce the simulation results and fabrication technology of dielectric-metal-dielectric long-range nanoplasmonic waveguides, which consists of a multilayer stack based on ultrathin noble metals in between alumina thin films. Various waveguide topologies are simulated to optimize all the geometric and multilayer stack parameters. We demonstrate the calculated propagation length of Lprop = 0.27 mm at the 785 nm wavelength for the Al2O3/Ag/Al2O3 waveguides. In addition, we numerically show the possibility to eliminate signal cross-talks (less than 0.01%) between two crossed waveguides. One of the key technology issues of such waveguides’ nanofabrication is a dry, low-damage-etching of a multilayer stack with extremely sensitive ultrathin metals. In this paper, we propose the fabrication process flow, which provides both dry etching of Al2O3/Au(Ag)/Al2O3 waveguides nanostructures with high aspect ratios and non-damage ultrathin metal films patterning. We believe that the proposed design and fabrication process flow provides new opportunities in next-generation photonic interconnects, plasmonic nanocircuitry, quantum optics and biosensors