We report that the p-xylylenediammonium ion (11) acts as a template in the cucurbit[n]uril forming reaction that biases the reaction toward the production of methylene bridged glycoluril hexamer (6C) and bis-nor-seco-CB[10]. Hexamer 6C is readily available on the gram scale by a one step synthetic procedure that avoids chromatography. Hexamer 6C undergoes macrocylization with (substituted) phthalaldehydes 12, 14, 15, and 18-in 9 M H(2)SO(4) or concd HCl at room temperature to deliver monofunctionalized CB[6] derivatives 13, 16, 17, and 19-that are poised for further functionalization reactions. The kinetics of the macrocyclization reaction between hexamer and formaldehyde or phthalaldehyde depends on the presence and identity of ammonium ions as templates. p-Xylylenediammonium ion (11) which barely fits inside CB[6] sized cavities acts as a negative template which slows down transformation of 6C and paraformaldehyde into CB[6]. In contrast, 11 and hexanediammonium ion (20) act as a positive template that promotes the macrocyclization reaction between 6C and 12 to deliver (±)-21 as a key intermediate along the mechanistic pathway to CB[6] derivatives. Naphthalene-CB[6] derivative 19 which contains both fluorophore and ureidyl C═O metal-ion (e.g., Eu(3+)) binding sites forms the basis for a fluorescence turn-on assay for suitable ammonium ions (e.g., hexanediammonium ion and histamine).

A supramolecular sensor array consisting of eight chemosensors embedded in a hydrogel matrix was used to sense carboxylate drugs. The discriminatory power of the array has been evaluated using principal component analysis and linear discriminant analysis. The eight-member sensor array has been shown to accurately identify 14 carboxylates in water with 100% classification accuracy. To demonstrate the potential for practical utility in the physiological environment, analysis of carboxylate drugs in human urine was also performed achieving 100% correct classification. In addition, the array performance in semiquantitative identification of nonsteroidal anti-inflammatory drugs has been investigated, and the results show that the sensor array is able to differentiate six typical nonsteroidal anti-inflammatory drugs at concentrations of 0.5-100 ppm. This illustrates the potential utility of the designed sensor array for diagnostic and environmental monitoring applications.

Biosensors based on organic field effect transistors (OFETs) are one of the more promising device applications in organic electronics. However, OFET-based biosensors are still in their early stages of development compared to other electrochemical biosensors. This study is the first to report on an extended-gate type organic field effect transistor (OFET) for lactate detection in aqueous media. Here, the extended-gate electrode of the OFET was modified with layers of a lactate oxidase and a horseradish peroxidase osmium-redox polymer on a flexible plastic film substrate for an enzymatic redox reaction of lactate. The device exhibited both high selectivity and sensitivity. The limit of detection (LOD) and the limit of quantification (LOQ) were estimated to be 66 nM and 220 nM, respectively, which are the sufficient detection limit for practical sensor applications. The obtained results confirm that extended-gate type OFET devices are applicable to enzyme-based biosensors for detecting lactate levels.

Amino acids and their derivatives are recognized and analyzed in water using a turn-on fluorescent cucurbituril based sensor array. Multivariate analysis (LDA and HCA) clearly shows that the sensor array can discriminate amino acids from the corresponding amines which are produced by the action of amino acid decarboxylases.

A supramolecular assay based on two fluorescent cucurbit[n]uril probes enables the recognition and quantification of nitrosamines, including cancer-associated nitrosamines, compounds that are difficult to recognize. The cross-reactive sensor leverages weak interactions and competition among the probe, metal, and guest, yielding high information density in the signal output (variance) and enabling the recognition of structurally similar guests.