Detection of TNT based on conjugated polymer encapsulated in mesoporous silica nanoparticles through FRET

Ultrafast on-site selective visual detection of TNT at sub-ppt level using fluorescent gold cluster incorporated single nanofiber

Single nanofiber embedded fluorescent gold cluster based sensor for selective detection of TNT at sub-ppt level.

Nanoconfinement of pyrene in mesostructured silica nanoparticles for trace detection of TNT in the aqueous phase

This article describes the preparation of pyrene confined mesostructured silica nanoparticles for the trace detection of trinitrotoluene (TNT) in the aqueous phase. Pyrene confined mesostructured silica nanoparticles were prepared using a facile one-pot method where pyrene molecules were first encapsulated in the hydrophobic parts of cetyltrimethylammonium micelles and then silica polymerized around these micelles. The resulting hybrid particles have sizes of around 75 nm with fairly good size distribution. Also, they are highly dispersible and colloidally stable in water. More importantly, they exhibit bright and highly stable pyrene excimer emission. We demonstrated that excimer emission of the particles exhibits a rapid, sensitive and visual quenching response against TNT. The detection limit for TNT was determined to be 12 nM. Furthermore, excimer emission of pyrene shows significantly high selectivity for TNT.

Hybrid aptamer-antibody linked fluorescence resonance energy transfer based detection of trinitrotoluene

Combining synthetic macromolecules and biomolecular recognition units are promising in developing novel diagnostic and analysis techniques for detecting environmental and/or clinically important substances. Fluorescence resonance energy transfer (FRET) apta-immunosensor for explosive detection is reported using 2,4,6-trinitrotoluene (TNT) specific aptamer and antibodies tagged with respective FRET pair dyes in a sandwich immunoassay format. FITC-labeled aptamer was used as a binder molecule in the newly developed apta-immunoassay format where the recognition element was specific anti-TNT antibody labeled with rhodamine isothiocyanate. The newly developed sensing platform showed excellent sensitivity with a detection limit of the order of 0.4 nM presenting a promising candidate for routine screening of TNT in samples.

A cationic iridium(iii) complex with aggregation-induced emission (AIE) properties for highly selective detection of explosives

A new AIE-active cationic Ir(iii) complex has been designed and synthesized, which exhibits highly sensitive and selective detection of explosives (TNP).

Novel PPV/mesoporous organosilica composites: influence of the host chirality on a conjugated polymer guest

The conjugated polymer poly(p-phenylenevinylene) (PPV) was polymerized in the pores of chiral nematic mesoporous organosilica to give a composite film showing the strong characteristic fluorescence of PPV as well as the iridescence due to the photonic band gap of the host material. Detailed circular dichroism (CD) studies reveal a chiral structure of the polymer within the pores. These new fluorescent materials undergo fluorescence quenching upon exposure to electron deficient aromatics such as 2,4,6-trinitrotoluene (TNT), indicating that they may be useful for developing chemical sensors.

Selective and efficient detection of nitro-aromatic explosives in multiple media including water, micelles, organogel, and solid support

Selective detection of nitro-aromatic compounds (NACs) at nanomolar concentration is achieved for the first time in multiple media including water, micelles or in organogels as well as using test strips. Mechanism of interaction of NACs with highly fluorescent p-phenylenevinylene-based molecules has been described as the electron transfer phenomenon from the electron-rich chromophoric probe to the electron deficient NACs. The selectivity in sensing is guided by the pKa of the probes as well as the NACs under consideration. TNP-induced selective gel-to-sol transition in THF medium is also observed through the reorganization of molecular self-assembly and the portable test trips are made successfully for rapid on-site detection purpose.

Conjugated amplifying polymers for optical sensing applications

Thanks to their unique optical and electrochemical properties, conjugated polymers have attracted considerable attention over the last two decades and resulted in numerous technological innovations. In particular, their implementation in sensing schemes and devices was widely investigated and produced a multitude of sensory systems and transduction mechanisms. Conjugated polymers possess numerous attractive features that make them particularly suitable for a broad variety of sensing tasks. They display sensory signal amplification (compared to their small-molecule counterparts) and their structures can easily be tailored to adjust solubility, absorption/emission wavelengths, energy offsets for excited state electron transfer, and/or for use in solution or in the solid state. This versatility has made conjugated polymers a fluorescence sensory platform of choice in the recent years. In this review, we highlight a variety of conjugated polymer-based sensory mechanisms together with selected examples from the recent literature.