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12 pages, 4792 KiB

Open AccessArticle

Synthesis of Zr-89-Labeled Folic Acid-Conjugated Silica (SiO₂) Microwire as a Tumor Diagnostics Carrier for Positron Emission Tomography

by Gun Gyun Kim, Hye Min Jang, Sung Bum Park, Jae-Seon So and Sang Wook Kim

Materials 2021, 14(12), 3226; https://doi.org/10.3390/ma14123226 - 11 Jun 2021

Cited by 2 | Viewed by 2438

Abstract

This study evaluated the in vivo behavior and accumulation of silica particles in the form of wires, which were actively studied as drug carriers along with spheres, using positron emission tomography (PET). Wire-shaped silicon dioxide (SiO₂) was synthesized at micro-size, using anodic aluminum oxide (AAO), a template, and folic acid (FA), which specifically binds folate receptors (FR) which are overexpressed in many cancers, and which was bound to the wire’s surface to confirm its possible use as a cancer diagnostic agent. In addition, for evaluation using PET, the positron-emitting nuclide ⁸⁹Zr (t_1/2 = 3.3 days) was directly bonded to the hydroxyl group (-OH) on the particle surface. The diameter and shape of the synthesized silica microwires (SMWs) were confirmed using SEM and TEM, the chemical bonding of FA was confirmed through FT–IR and NMR, and the labeling of ⁸⁹Zr was measured by means of radio-thin-layer chromatography (TLC) measurement. Folic acid-conjugated SMWs (FA-SMWs) were found to have a low receptor-mediated uptake in cell internalization evaluation, but in PET studies, FA-SMWs stayed longer at the tumor site. In conclusion, we successfully synthesized a homogeneous silica microwire for drug delivery, we confirmed that the FA-conjugated sample remains at the tumor site for a relatively longer time, and we have reported the characteristic in vivo behavior of ⁸⁹Zr-FA-SMWs. Full article

(This article belongs to the Special Issue Functionalized Silica Materials: Preparation and Applications)

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17 pages, 5490 KiB

Open AccessArticle

Optical Micro-Wire Flow-Velocity Sensor

by Matej Njegovec, Simon Pevec and Denis Donlagic

Sensors 2021, 21(12), 4025; https://doi.org/10.3390/s21124025 - 10 Jun 2021

Cited by 5 | Viewed by 3800

Abstract

This paper presents a short response time, all-silica, gas-flow-velocity sensor. The active section of the sensor consists of a 16 µm diameter, highly optically absorbing micro-wire, which is heated remotely by a 980 nm light source. The heated microwire forms a Fabry–Perot interferometer whose temperature is observed at standard telecom wavelengths (1550 nm). The short response time of the sensor allows for different interrogation approaches. Direct measurement of the sensor’s thermal time constant allowed for flow-velocity measurements independent of the absolute heating power delivered to the sensor. This measurement approach also resulted in a simple and cost-efficient interrogation system, which utilized only a few telecom components. The sensor’s short response time, furthermore, allowed for dynamic flow sensing (including turbulence detection). The sensor’s bandwidth was measured experimentally and proved to be in the range of around 22 Hz at low flow velocities. Using time constant measurement, we achieved a flow-velocity resolution up to 0.006 m/s at lower flow velocities, while the resolution in the constant power configuration was better than 0.003 m/s at low flow velocities. The sensing system is constructed around standard telecommunication optoelectronic components, and thus suitable for a wide range of applications. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 999 KiB

Open AccessArticle

Modified Powder-in-Tube Technique Based on the Consolidation Processing of Powder Materials for Fabricating Specialty Optical Fibers

by Jean-Louis Auguste, Georges Humbert, Stéphanie Leparmentier, Maryna Kudinova, Pierre-Olivier Martin, Gaëlle Delaizir, Kay Schuster and Doris Litzkendorf

Materials 2014, 7(8), 6045-6063; https://doi.org/10.3390/ma7086045 - 22 Aug 2014

Cited by 23 | Viewed by 8121

Abstract

The objective of this paper is to demonstrate the interest of a consolidation process associated with the powder-in-tube technique in order to fabricate a long length of specialty optical fibers. This so-called Modified Powder-in-Tube (MPIT) process is very flexible and paves the way to multimaterial optical fiber fabrications with different core and cladding glassy materials. Another feature of this technique lies in the sintering of the preform under reducing or oxidizing atmosphere. The fabrication of such optical fibers implies different constraints that we have to deal with, namely chemical species diffusion or mechanical stress due to the mismatches between thermal expansion coefficients and working temperatures of the fiber materials. This paper focuses on preliminary results obtained with a lanthano-aluminosilicate glass used as the core material for the fabrication of all-glass fibers or specialty Photonic Crystal Fibers (PCFs). To complete the panel of original microstructures now available by the MPIT technique, we also present several optical fibers in which metallic particles or microwires are included into a silica-based matrix. Full article

(This article belongs to the Special Issue New Materials and Processing Methods for Microstructured Optical Fibres)

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