Sensors colorimetric detection

Wang C, Ma Z. Colorimetric detection of ohgonucleotides using a polydiacetylene vesicle sensor. Anal Bioanal Chem 2005 382 1708-1710. 

James and coworkers [38] have synthesized an azo dye molecule with boronic acid, receptor 40, which can act as a colorimetric sensor for detection... 

The performance of sequential injection electrochemical immunoassay of TCP was studied. The linear measuring range was 0.01 to 0.02 qg/L, and the relative standard deviation was below 3.9% (n = 6). The detection limit of the sensor for TCP at 6 ng/L (ppt) is roughly 50 times lower than that of TCP RaPID Assay kit (at 0.25 qg/L, colorimetric detection). 

Fluorescent and colorimetric sensors for detection of lead, cadmium, and mercury ions 12CSR3210. 

Numerous colorimetric sensors for detecting chemical species have been reported in the literature. In particular. 

Figure 4 (a) A schematic representation of the colorimetric detection systems of optically monolithic cage sensors and the... 

Huang CC, Chang HT (2006) Selective gold-nanoparticle-based tum-on fluorescent sensors for detection of mercury(II) in aqueous solution. Anal Chem 78 8332-8338 He X, Liu H, Li Y et al (2005) Gold nanoparticle-based fluorometric and colorimetric sensing of copper(II) ions. Adv Mater 17 2811-2815... 

Ding B, Si Y, Wang X, Yu J, Feng L, Sun G (2011) Label-free ultrasensitive colorimetric detection of copper(ll) ions utilizing polyaniline/polyamide-6 nano-fiber/net sensor strips. J Mater Chem 21(35) 13345-13353. doi 10.1039/cljmll851j... 

Brinkley et al. demonstrated89 a simple to use, easy to interpret, low cost, and environmentally friendly colorimetric detector of the chemical warfare agent - mustard gas (HD, l,l-thiobis(2-chloroethane)). An optically transparent xerogel encapsulating Cu(II) acetate was fabricated to detect HD analogues and can serve as the optical sensor based on metal-ligand charge-transfer mechanism. 

Acoustic wave sensors are also used to detect nerve and blister agents. The surface acoustic wave chemical agent detector (SAW Mini-CAD) is a commercially available, pocket-sized instrument that can monitor for trace levels of toxic vapors of sulfur-based mustard agents (e.g., distilled mustard) and G nerve agents (e.g., tabun, sarin, soman) with a high degree of specificity. Colorimetric tubes are the... 

The sensors discussed so far are based on ligands covalently bound to the polymer backbone. Other methods of detection - often referred to as mix and detect methods - work by simple noncovalent incorporation of the polymer with the ligand of interest. Reichert et al. generated liposomes of polydiacetylene with sialic acid for the same purpose of detection as Charych s surface-bound polymers, but realized that covalent functionalization of the polymer was not necessary [17]. Through simple mixing of the lipid-bound sialic acid with the polymer before sonication and liposome formation, they were able to form a functional colorimetric recognition system (Fig. 8). 

Reflectance measurements provided an excellent means for building an ammonium ion sensor involving immobilization of a colorimetric acid-base indicator in the flow-cell depicted schematically in Fig. 3.38.C. The cell was furnished with a microporous PTFE membrane supported on the inner surface of the light window. The detection limit achieved was found to depend on the constant of the immobilized acid-base indicator used it was lO M for /7-Xylenol Blue (pAT, = 2.0). The response time was related to the ammonium ion concentration and ranged from 1 to 60 min. The sensor remained stable for over 6 months and was used to determine the analyte in real samples consisting of purified waste water, which was taken from a tank where the water was collected for release into the mimicipal waste water treatment plant. Since no significant interference fi-om acid compounds such as carbon dioxide or acetic acid was encountered, the sensor proved to be applicable to real samples after pH adjustment. The ammonium concentrations provided by the sensor were consistent with those obtained by ion chromatography, a spectrophotometric assay and an ammonia-selective electrode [269]. 

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