Synthesis of Prussian blue-embedded porous polymer for detection and removal of Cs ions

A Prussian blue (PB)​-​embedded coordination polymer (COP) was prepd. by simple incorporation of PB into a COP composed of 1,​1,​2,​2-​tetrakis(4-​carboxyphenyl)​ethane and the Zn ion during the synthesis of COP. The PB-​COP was prepd. as micro-​sized particles with green emission (490 nm) from the strongly fluorescent tetraphenylethene group in the solid state through aggregation-​induced emission. The PB-​COP showed particle shape with sizes ranging from 1 to 6 μm. As the PB in PB-​COP efficiently adsorbed Cs ions, the microstructure of PB-​COP was degraded to smaller particles, along with a concomitant decrease in the green fluorescence of the PB-​COP. Such a decrease in the green emission of PB-​COP was used as a signal for the presence of Cs ions, in which the limit of detection for Cs ions was found to be 73.8 ppb. The hybridized material of the PB-​COP can be used as both an efficient adsorbent and a sensor for Cs ions, achieving simultaneous removal and detection

A Bug Triage Technique Using Developer-Based Feature Selection and CNN-LSTM Algorithm

With an increase in the use of software, the incidence of bugs and resulting maintenance costs also increase. In open source projects, developer reassignment accounts for approximately 50%. Software maintenance costs can be reduced if appropriate developers are recommended to resolve bugs. In this study, features are extracted by applying feature selection for each developer. These features are entered into CNN-LSTM algorithm to learn the model and recommend appropriate developers. To compare the performance of the proposed model, open source projects (Google Chrome, Mozilla Core, and Mozilla Firefox) were used to compare the performance of the proposed method with a baseline for developer recommendation. In this paper, the performance showed 54% for F-measure and 52% for accuracy in open source projects. The proposed model has improved and showed about a 13% more effective performance improvement than with DeepTriage. It was discovered that the performance of the proposed model was better

Turn-on detection of Cs Ions based on conjugated polymer-graphene oxide

New type of “turn-on” fluorescent sensor for Cs ion was developed using a composite of blue-emissive conjugated polymer (CP) and graphene oxide (GO). Ethylene glycol units were introduced to the side chain of CP, which could interact with Cs ions. The CP and GO formed a stable, nonfluorescent composite, because of hydrophobic and ππ interactions between them. In the presence of Cs ions, the CP was released from the CP-GO composite because of higher affinity of Cs ions with ethylene glycol units in the CP. Such a weaker interaction between CP and GO led to the recovery of initial blue fluorescence of the CP. The degree of fluorescence restoration would be a measure of the concentration of Cs ions. Thus, fluorescence “turn-on” from CP-GO was attributed to the presence of Cs ions

New Fluorescent Metal-Ion Detection Using a Paper-Based Sensor Strip Containing Tethered Rhodamine Carbon Nanodots

A strip of tethered rhodamine carbon nanodots (C-dots) was designed for selective detection of Al³⁺ ion using a Förster resonance energy transfer (FRET)-based ratiometric sensing mechanism. The probe consisted of rhodamine B moieties immobilized on the surface of water-soluble C-dots. Upon exposure to Al³⁺, the rhodamine moieties showed a much enhanced emission intensity via energy transfer from the C-dots under excitation at their absorption wavelength. The detection mechanism was related to the Al³⁺-induced ring-opening of rhodamine on C-dots through the chelation of the rhodamine 6G moiety with Al³⁺, leading to a spectral overlap of the absorption of C-dots (donor) and the emission of ring-opened rhodamine (acceptor). In addition, a paper-based sensor strip containing the tethered rhodamine C-dots was prepared for practical, versatile applications of Al³⁺ sensing. The paper-based sensor could detect Al³⁺ over other metal ions efficiently, even from a mixture of metal ions, with increased emission intensity at long-wavelength emission via FRET. Sensing based on FRET of C-dots is color-tunable, can be recognized with a naked eye, and may provide a new platform for specific metal-ion sensing

Design principles of chemiluminescence (CL) chemodosimeter for self-signaling detection: luminol protective approach

Chemiluminescence (CL) sensors can provide convenience and high sensitivity because they do not require an external excitation light source to produce a fluorescence signal. However, most CL based detection systems do not have a built-in self-signaling process, leading to inefficient and complex protocols due to the required multistep cascade reactions. Here, we develop a CL based sensory system with a built-in self-signaling feature by adapting the chemodosimeter concept. We found that a masking group incorporated to luminol efficiently suppresses the CL of luminol and that selective removal of the masking group by a target analyte can turn on the CL process, generating a sensitive fluorescence turn-on signal. Through systematic studies on newly devised TBS-luminol and TIPS-luminol, we optimized the molecular design parameters to achieve a highly sensitive and selective CL chemodosimeter. The optimized conditions rendered highly sensitive (Limit of Detection (LOD) = 18 nM) and selective fluoride sensing in aqueous environments. We anticipate that our new sensor system offers an efficient way to achieve highly sensitive, selective, and convenient CL turn-on detection of various important analytesclos

Conjugated Polymer Dots-on-Electrospun Fibers as a Fluorescent Nanofibrous Sensor for Nerve Gas Stimulant

A novel chemical warfare agent sensor based on conjugated polymer dots (CPdots) immobilized on the surface of poly­(vinyl alcohol) (PVA)–silica nanofibers was prepared with a dots-on-fibers (DoF) hybrid nanostructure via simple electrospinning and subsequent immobilization processes. We synthesized a polyquinoxaline (PQ)-based CP as a highly emissive sensing probe and employed PVA–silica as a host polymer for the elctrospun fibers. It was demonstrated that the CPdots and amine-functionalized electrospun PVA–silica nanofibers interacted via an electrostatic interaction, which was stable under prolonged mechanical force. Because the CPdots were located on the surface of the nanofibers, the highly emissive properties of the CPdots could be maintained and even enhanced, leading to a sensitive turn-off detection protocol for chemical warfare agents. The prepared fluorescent DoF hybrid was quenched in the presence of a chemical warfare agent simulant, due to the electron transfer between the quinoxaline group in the polymer and the organophosphorous simulant. The detection time was almost instantaneous, and a very low limit of detection was observed (∼1.25 × 10^–6 M) with selectivity over other organophosphorous compounds. The DoF hybrid nanomaterial can be developed as a rapid, practical, portable, and stable chemical warfare agent-detecting system and, moreover, can find further applications in other sensing systems simply by changing the probe dots immobilized on the surface of nanofibers

Molecular Design Approach for Directed Alignment of Conjugated Polymers

Macroscopic alignment of conjugated polymers (CPs) is essential to fully realize the anisotropic optical and electronic properties of CPs, originated from the one-dimensional -orbital overlap along the conjugated backbone, in the solid-state devices. Various CP-processing approaches to achieve CP alignment have been explored. However, molecular design to enable CP alignment has not been fully understood. Herein, we report a thorough investigation into molecular design parameters critically affecting CP alignment characteristics. First, we present a series of CPs with newly designed building blocks reflecting the previously identified preliminary design principles to validate the general applicability of the identified CP design parameters for alignment. Furthermore, newly defined design factors correlating with CP alignment characteristics are systematically studied, including the planarity of CP main chain, the effect of the side-chain design, intramolecular interaction moiety for induced chain planarity, and the surface energy of CPs. Utilizing aligned CP films, we also demonstrated the optical switching of organic thin-film transistor (OTFT) devices. Depending on the orientation of polarized light illumination, different amounts of photocurrent gain were observed. The on-to-off switching ratio (Ion/Ioff) under illumination was ca. 7.2 × 104, which is large enough for an OTFT to operate by an optical as well as an electrical trigger. © 2019 American Chemical Society.N

Highly Selective Cysteine Detection and Bioimaging in Zebrafish through Emission Color Change of Water-Soluble Conjugated Polymer-Based Assay Complex

A new concept for rapid, label-free cysteine sensing method is proposed via possible naked eye-detection of red-to-blue emission color change. Intermolecular exciton migration in conjugated polyelectrolyte-based assay complex is adopted to enhance selectivity and sensitivity for cysteine sensing by formation and dissociation of polymer–Hg²⁺–thymine assay complex in the absence and presence of cysteine, respectively. The assay complex shows red emission due to cooperative aggregation of conjugated polyelectrolyte, thymine, and Hg²⁺. Upon exposure to cysteine, the assay complex dissociates into individual molecules showing transparent, blue-emitting solution, because cysteine extracts Hg²⁺ from the assay complex via more favorable binding between cysteine and Hg²⁺

Molecular Design Approach for Directed Alignment of Conjugated Polymers

Macroscopic alignment of conjugated polymers (CPs) is essential to fully realize the anisotropic optical and electronic properties of CPs, originated from the one-dimensional pi-orbital overlap along the conjugated backbone, in the solid-state devices. Various CP-processing approaches to achieve CP alignment have been explored. However, molecular design to enable CP alignment has not been fully understood. Herein, we report a thorough investigation into molecular design parameters critically affecting CP alignment characteristics. First, we present a series of CPs with newly designed building blocks reflecting the previously identified preliminary design principles to validate the general applicability of the identified CP design parameters for alignment. Furthermore, newly defined design factors correlating with CP alignment characteristics are systematically studied, including the planarity of CP main chain, the effect of the side-chain design, intramolecular interaction moiety for induced chain planarity, and the surface energy of CPs. Utilizing aligned CP films, we also demonstrated the optical switching of organic thin-film transistor (OTFT) devices. Depending on the orientation of polarized light illumination, different amounts of photocurrent gain were observed. The on-to-off switching ratio (I-on/I-off) under illumination was ca. 7.2 x 10(4), which is large enough for an OTFT to operate by an optical as well as an electrical trigger