Xianghan Zhang

Band-Notched UWB Printed Antenna with an Inverted C-Slotted Ground

A novel printed antenna having a frequency band-notched function for UWB applications is proposed and studied. With a pair of inverted C-shaped slots introduced around the microstrip line on the ground, a frequency-notched response at 5.2 GHz is obtained. The designed antenna satisfies the VSWR requirement of less than 2.0 in the frequency band between 2.8 and 10.7 GHz while showing the band rejection performance in the frequency band from 4.8 to 5.7 GHz. Good monopole-like radiation patterns and antenna gains have also been obtained.

Nonplanar Monocyanines: Meso-Substituted Thiazole Orange with High Photostability and Their Synthetic Strategy as well as a Cell Association Study

A convenient approach for the direct synthesis of meso-substituted thiazole orange (meso-TO) analogues has been unprecedentedly developed through the AlCl3-catalyzed reaction of parent TO with benzyl alcohol derivatives. Single-crystal X-ray structures show that the prepared new meso-TO analogues are nonplanar, forming a sharp contrast to planar TO. The spectral properties show that nonplanar meso-TO analogues do not aggregate, existing in monomer form (M) in PBS buffer, and have little effect of solvatochromism in different solvents. In comparison with the parents, meso-TO analogues exhibit a large Stokes shift, excellent light fastness, and inertness to singlet oxygen. A cellular association study demonstrates that incorporation of a benzyl group at the meso position methine of parent TO can decrease the cytotoxicity, change staining area in cells, and emit long-wavelength fluorescence for an extended time, which are useful for the development of smarter TOs for imaging in biological science.

Improved Tumor Targeting and Longer Retention Time of NIR Fluorescent Probes Using Bioorthogonal Chemistry

The traditional labeling method for targeted NIR fluorescence probes requires directly covalent-bonded conjugation of targeting domains and fluorophores in vitro. Although this strategy works well, it is not sufficient for detecting or treating cancers in vivo, due to steric hindrance effects that relatively large fluorophore molecules exert on the configurations and physiological functions of specific targeting domains. The copper-free, “click-chemistry”-assisted assembly of small molecules in living systems may enhance tumor accumulation of fluorescence probes by improving the binding affinities of the targeting factors. Here, we employed a vascular homing peptide, GEBP11, as a targeting factor for gastric tumors, and we demonstrate its effectiveness for in vivo imaging via click-chemistry-mediated conjugation with fluorescence molecules in tumor xenograft mouse models. This strategy showed higher binding affinities than those of the traditional conjugation method, and our results showed that the tumor accumulation of click-chemistry-mediated probes are 11-fold higher than that of directly labeled probes. The tracking life was prolonged by 12-fold, and uptake of the probes into the kidney was reduced by 6.5-fold. For lesion tumors of different sizes, click-chemistry-mediated probes can achieve sufficient signal-to-background ratios (3.5-5) for in vivo detection, and with diagnostic sensitivity approximately 3.5 times that of traditional labeling probes. The click-chemistry-assisted detection strategy utilizes the advantages of “small molecule” probes while not perturbing their physiological functions; this enables tumor detection with high sensitivity and specific selectivity.

Design of Wideband Microstrip-Fed Plannar Monopole Antenna for Multiband Applications

A novel printed wideband monopole antenna for multiband operations is presented. Good impedance matching in a wide dual-band can be achieved by a simple circular monopole and a rectangular conductor-backed plane with a square hole. The measured 10 dB bandwidth for return loss is from 1.78 to 4.19 GHz about 80% and 5.12 to 6.35 GHz about 21.4% which covering all the 2.4/5.2/5.8 GHz WLAN, 2.5/3.5/5.5 GHz WiMAX, DCS (1710–1880 MHz), PCS (1850–1990 MHz), UMT (1920–2170 MHz), and IMT-2000 (1900–2025 MHz) bands applications. Peak antenna gains have been obtained about 3.39 and 3.96 dBi for the lower and upper bands, respectively.

Dual-Band Monopole Antenna with a Novel Conductor-Backed Plane

In this paper, we propose a novel printed wideband monopole antenna with simple structure and compact size. The proposed antenna can provide two separate impedance bandwidths of 1.55 GHz about 48.8% (from 2.4 to 3.95 GHz) and 1.275 GHz about 22.4% (from 5.05 to 6.325 GHz), making it easily cover the required bandwidths for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) operations. Also, good antenna performances such as radiation patterns and antenna gains over the operating bands have been observed. Details of the proposed antenna design and experimental results are presented and discussed.

In Vivo and in Situ Activated Aggregation-Induced Emission Probes for Sensitive Tumor Imaging Using Tetraphenylethene-Functionalized Trimethincyanines-Encapsulated Liposomes

The design and exploration of fluorescent probes with high-sensitivity and low-background are essential for noninvasive optical molecular imaging. The in vivo and in situ activated aggregation-induced emission (AIE) probes were found to be ideal for achieving higher signal-to-background ratios for tumor detections. We herein developed novel tetraphenylethene-encapsulated liposomes (TPE-LPs) constructed by loading TPE-trimethincyanine into liposomes for the first time, and the probes were applied to tumor bioimaging in vivo. TPE-functionalized trimethincyanines were synthesized with a new and efficient one-pot reaction. In TPE-LPs, TPE-functionalized bicarboxylic acids benzoindole trimethinecyanine (TPE-BICOOH) fluorophores were found to be well dispersed in lipid bilayers (with non-restricted rotation) during the blood circulation, and then aggregated (with restriction of intramolecular rotation) upon liposome rupture in the tumor tissue, achieving a low-background and high-target signal for tumor imaging. The in situ activated AIE probes not only had great accumulation at the tumor site after intravenous injection in 4T1 tumor-bearing mice but also demonstrated excellent signal-to-background ratios, as well as low cytotoxicity and excellent biocompatibility. The proposed strategy is believed to be a simple and powerful tool for the sensitive detection of tumors.

Small Printed Ultra-Wideband Antenna with Subband Rejection Capability

A small printed antenna is described with subband rejection for ultrawideband (UWB) applications [1]. Two notches are incorporated in the radiating structure of the antenna to act as a bandstop filter to reject the undesired subband within the whole bandwidth [2]. The designed antenna features a compact size of 26×25 mm2, and satisfies the VSWR requirement of less than 2.0 in the frequency band from 3 GHz to more than 12 GHz excluding any undesired subband such as 4.65–5.65 GHz. Good monopole-like radiation patterns and antenna gains have also been obtained.