Insect odorant receptor-based biosensors: Current status and prospects.

Whilst the senses of vision and hearing have been successfully automated and miniaturized in portable formats (e.g. smart phone), this is yet to be achieved with the sense of smell.

Pixelated colorimetric nucleic acid assay.

Conjugated polyelectrolytes (CPEs) have been widely used as reporters in colorimetric assays targeting nucleic acids. CPEs provide naked eye detection possibility by their superior optical properties however, as concentration of target analytes decrease, trace amounts of nucleic acid typically yield colorimetric responses that are not readily perceivable by naked eye. Herein, we report a pixelated analysis approach for correlating colorimetric responses of CPE with nucleic acid concentrations down to 1 nM, in plasma samples, utilizing a smart phone with an algorithm that can perform analytical testing and data processing.

Flow-through colorimetric assay for detection of nucleic acids in plasma.

A flow-through colorimetric assay for detection of nucleic acids in plasma is reported. The proposed assay features an array of four polyvinylidene fluoride (PVDF) membranes impregnated with cationic poly (3-alkoxy-4-methylthiophene) (PT) as an optical reporter. The sensing strategy is based on monitoring the changes in optical properties of PT, upon complexation with target nucleic acids in the presence and in the absence of their corresponding complementary peptide nucleic acids (PNAs).

Data on preparation and characterization of an insect odorant receptor based biosensor.

Insect Odorant receptors (OrXs) can be used as the recognition element in a biosensor as they demonstrate high levels of sensitivity and selectivity towards volatile organic compounds. Herein, we describe a method to express and purify insect odorant receptors and reconstitute them into artificial lipid bilayers (liposomes). These OrX/liposomes were covalently attached to a gold surface and characterized using quartz crystal microbalance with dissipation monitoring (QCM-D).

An ultrasensitive electrochemical impedance-based biosensor using insect odorant receptors to detect odorants.

Herein, we present that insect odorant receptors reconstituted into the lipid bilayers of liposomes can be successfully immobilized onto a gold surface and selectively and sensitively detect odorant molecules. The odorant receptors (OrXs) Or10a, Or22a, and Or71a from the common fruit fly, Drosophila melanogaster, were recombinantly expressed, purified and integrated into nano-liposomes (100-200 nm). These liposomes were covalently attached to the self-assembled monolayers (SAMs) of a 6-mercaptohexanoic acid (MHA)-modified gold surface.

Tailoring Conformation-Induced Chromism of Polythiophene Copolymers for Nucleic Acid Assay at Resource Limited Settings.

Here we report on the design and synthesis of cationic water-soluble thiophene copolymers as reporters for colorimetric detection of microRNA (miRNA) in human plasma. Poly(3-alkoxythiophene) (PT) polyelectrolytes with controlled ratios of pendant groups such as triethylamine/1-methyl imidazole were synthesized for optimizing interaction with target miRNA sequence (Tseq). Incorporation of specific peptide nucleic acid (PNA) sequences with the cationic polythiophenes yielded distinguishable responses upon formation of fluorescent PT-PNA-Tseq triplex and weakly fluorescent PT-Tseq duplex, thereby enabling selective detection of target miRNA.

Polythiophene derivative on quartz resonators for miRNA capture and assay.

A novel approach for miRNA assay using a cationic polythiophene derivative, poly[3-(3'-N,N,N-triethylamino-1'-propyloxy)-4-methyl-2,5-thiophene hydrobromide] (PT), immobilized on a quartz resonator is proposed. The cationic PT enables capturing of all RNA sequences in the sample matrix via electrostatic interactions, resulting in the formation of PT-RNA duplex structures on quartz resonators. Biotinylated peptide nucleic acid (b-PNA) sequences are subsequently utilized for the RNA assay, upon monitoring the PT-RNA-b-PNA triplex formation.