Paper and nylon based optical tongues with poly(p-phenyleneethynylene)-fluorophores efficiently discriminate nitroarene-based explosives and pollutants.

Discrimination of nitroarenes with hydrophobic dyes in a polar (H2O) environment is difficult but possible via a lab-on-chip, with polymeric dyes immobilized on paper or nylon membranes. Here arrays of 12 hydrophobic poly(p-phenyleneethynylene)s (PPEs), are assembled into a chemical tongue to detect/discriminate nitroarenes in water. The changes in fluorescence image of the PPEs when interacting with solutions of the nitroarenes were recorded and converted into color difference maps, followed by cluster analysis methods. The variable selection method for both paper and nylon devices selects a handful of PPEs at different pH-values that discriminate nitroaromatics reliably. The paper-based chemical tongue could accurately discriminate all studied nitroarenes whereas the nylon-based devices represented distinguishable optical signature for picric acid and 2,4,6-trinitrotoluene (TNT) with high accuracy.

Phosphatidylserine-exposing extracellular vesicles in body fluids are an innate defence against apoptotic mimicry viral pathogens.

Some viruses are rarely transmitted orally or sexually despite their presence in saliva, breast milk, or semen. We previously identified that extracellular vesicles (EVs) in semen and saliva inhibit Zika virus infection. However, the antiviral spectrum and underlying mechanism remained unclear. Here we applied lipidomics and flow cytometry to show that these EVs expose phosphatidylserine (PS). By blocking PS receptors, targeted by Zika virus in the process of apoptotic mimicry, they interfere with viral attachment and entry. Consequently, physiological concentrations of EVs applied in vitro efficiently inhibited infection by apoptotic mimicry dengue, West Nile, Chikungunya, Ebola and vesicular stomatitis viruses, but not severe acute respiratory syndrome coronavirus 2, human immunodeficiency virus 1, hepatitis C virus and herpesviruses that use other entry receptors. Our results identify the role of PS-rich EVs in body fluids in innate defence against infection via viral apoptotic mimicries, explaining why these viruses are primarily transmitted via PS-EV-deficient blood or blood-ingesting arthropods rather than direct human-to-human contact.

A poly(arylene ethynylene)-based microfluidic fluorescence sensor array for discrimination of polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons (PAHs) are persistent contaminants in the environment. Several of them have carcinogenic properties. There is considerable interest in their sensitive low-cost detection and monitoring. We present a simple paper-based microfluidic sensor for the rapid detection of PAHs. Craft punch patterning generated multiple detection zones inhabited by fluorescent poly(arylene ethynylene)s (PAEs). Changes in fluorescence image and/or intensity of the sensor array were recorded using a smartphone camera. The RGB color values of the photographed images were extracted through ImageJ software. 10 different PAHs were correctly identified using Principal Component Analysis and discrimination analysis (PCA-DA). 100% classification accuracy was achieved for model training, whereas validating the PCA-DA model by cross-validation resulted in 93% classification accuracy for 5.0 mg L-1 analyte.

Sensor Array Based Determination of Edman Degradated Amino Acids Using Poly(p-phenyleneethynylene)s.

A cross-reactive optical sensor array based on poly(p-phenyleneethynylene)s (PPEs) determines Edman degraded amino acids. We report a sensor array composed of three anionic PPEs P1-P3, and their electrostatic complexes with metal ions (Fe2+ , Cu2+ , Co2+ ). We recorded distinct fluorescence intensity response patterns as "fingerprints" of this chemical tongue toward standard phenylthiohydantoin (PTH) amino acids-degradation products of the Edman process. These "fingerprints" were converted into canonical scores by linear discrimination analysis (LDA), which differentiates all of the PTH-amino acids. This array discriminates PTH-amino acid residues degraded from an oligopeptide through Edman sequencing. This approach is complementary to chromatography approaches which rely on mass spectrometry; our array offers the advantage of simplicity.

Simple and robust polymer-based sensor for rapid cancer detection using serum.

We report a polymer-based sensor that rapidly detects cancer based on changes in serum protein levels. Using three ratiometric fluorescence outputs, this simple system identifies early stage and metastatic lung cancer with a high level of accuracy exceeding many biomarker-based assays, making it an attractive strategy for point-of-care testing.

Novel Functional TPE Polymers: Aggregation-Induced Emission, pH Response, and Solvatochromic Behavior.

Four tetraphenylethylene (TPE)-based aryleneethynylene polymers with amino or nitro groups are reported. They display strong aggregation-induced emission (AIE). The functional groups trigger acidochromic changes in the emission behavior of these polymers. Amino-substituted P1-P3 exhibit pH response through protonation of the amino groups. The position of the amino groups (on TPE or the side chains) influences the fluorescence intensity or emission wavelength as a response to different pH values. Nitro-P4 is solvatochromic due to its donor-acceptor structure. AIE, intramolecular charge transfer, and Förster resonance energy transfer define the fluorescence-based performance of the polymers. The amino-functionalized TPE polymers show excellent nitroarene-sensing performance. P4 is less effective than the amino polymers. A sensor array based on P1-P3 identifies 12 different nitroarenes in water.

Detecting Counterfeit Brandies.

A hypothesis-free sensor array (optoelectronic tongue) composed of an anionic, a cationic and two neutral poly(para-aryleneethynylene)s (PAE) at pH 3, 7 and 13 discriminate more than 30 spirits (including brandy, Branntwein, Cognac, Spirituose, and Weinbrand). Counterfeits (made by mixing of low-quality spirits and caramel colour) and different batches of identical brands of brandies are discriminated. The sensor array works without sample preparation or great instrumental cost, and is superior to conventional methods with respect to sample need (10-20 µL), time and effort. The discrimination stems from differential fluorescence quenching of the PAE-array by the complex mixture of the beverages' colourants, from the oak barrels or added caramel colour. The collected quenching data were analysed by linear discriminant analysis (LDA) and principal component analysis (PCA) to achieve successful discrimination.

Immobilized Poly(aryleneethynylene) pH†Strips Discriminate Different Brands of Cola.

Fluorescent, water-soluble poly(p-aryleneethynylene)s (PAE) were immobilized on commercially available nylon membranes by using a slot plotter, creating fluorescent, barcode-like sensor strips. Digital imaging by using a standard digital camera, before and after immersion of the strips in buffers of different pH, displays a unique color for each pH value. Statistical evaluation, multivariate analysis of variance (MANOVA) and principal component analysis (PCA), of the acquired data revealed that the immobilized PAEs are superior to the identical fluorophores when dissolved. The pH sensor array discriminates 20 different brands of commercial-cola soft drinks through differences in pH and colorant-PAE interactions.

An Optimized Sensor Array Identifies All Natural Amino Acids.

Wet-chemical discrimination of amino acids is still a challenge due to their structural similarity. Here, an optimized self-assembled eight-member sensor array is reported. The optimized sensor array stems from the combination of elements of different tongues, containing poly( para-phenyleneethynylene)s (PPE) and a supercharged green fluorescent protein (GFP) variant. The responsivity of the sensor dyes (PPEs and GFP) is enhanced in elements that contain adjuvants, such as metal salts but also cucurbit[7]uril (CB[7]) and acridine orange; a suitable and robust eight element array discriminates all of the 20 natural amino acids in water at 25 mM concentration with 100% accuracy. The results group well to the amino acid type, i.e., hydrophobic, polar, and aromatic ones.

An Optical Sensor Array Discriminates Syrups and Honeys.

We report a cross-reactive sensor array, combining a two-component probe system based upon three viologen substituted boronic acids and a poly(aryleneethynylene) (PAE) and an additional number of simple PAEs alone. This combined system discriminates 27 different honeys in aqueous solution, according to patterns in fluorescence intensity modulation, using linear discriminant analysis for data processing. The fluorescence turn-on array detects saccharide composition, while the PAEs discriminate trace colored components in the honeys.

Molecular Wire Effects in Phenyleneethynylene Oligomers: Surprising Insights.

The synthesis and quenching behavior of a series of water-soluble, carboxylate-carrying phenyleneethynylene oligomers-monomer to tetramer-and their polymers are reported; their quenching behavior with different test analytes (paraquat, lead salts, mercury salts, picric acid, methylpyridinium iodide) in water were investigated, and the results were compared to that of the conjugated polymer. Significant but analyte-dependent enhancement effects were found. For monovalent quenchers, only the molecular wire effect applies, but for divalent quenchers multivalency effects are also important.

Poly(para-phenyleneethynylene)-Sensor Arrays Discriminate 22 Different Teas.

Two nine-element sensor arrays, consisting of either three cationic poly(para-phenyleneethynylene)s (PPE) or the same PPEs complexed by cucurbituril[8] (CB[8]) at pH 3, 7, and 13 in water, discriminate 22 different teas and some of their small molecule components, including caffeine, theobromine and theophylline. Both arrays distinguish all of the black, green and oolong teas. The discrimination occurs by differential fluorescence modulation of the components of the sensor array and the treatment of the collected data by linear discriminant analysis. The signal is generated by either simple quenching (PPE only array) or the disruption of the PPE/CB[8] complex and quenching of the complex's or the PPEs' fluorescence through the polyphenolic colorants of the teas. Added amino acids, theobromine, theophylline, and caffeine give a fluorescence turn on of the PPE-CB[8] array, due to the disruption of the self-assembled complex, while for the PPE-alone tongue only caffeine, theobromine, and theophylline elicited useful fluorescence response. Both tongues discriminate different teas without any problem.

Fingerprinting antibiotics with PAE-based fluorescent sensor arrays.

We outline an evolution process for tongue elements composed of poly(p-aryleneethynylene)s (PAE) and detergents, resulting in a chemical tongue (24 elements) that discerns antibiotics. Cross-breeding of this new tongue with tongue elements that consist of simple poly(p-phenyleneethynylene)s (PPE) at different pH-values leads to an enlarged sensor array, composed of 30 elements. This tongue was pruned, employing principal component analysis. We find that a filial tongue featuring three elements from each original array (i.e. a six element tongue) is superior to either of the prior tongues and the composite tongue in the discrimination of structurally different antibiotics. Such a selection process should be general and give an idea how to successfully generate powerful low-selectivity sensor elements and configure them into discriminative chemical tongues.

A Polymer/Peptide Complex-Based Sensor Array That Discriminates Bacteria in Urine.

A negatively charged poly(para-phenyleneethynylene) (PPE) forms electrostatic complexes with four positively charged antimicrobial peptides (AMP). The AMPs partially quench the fluorescence of the PPE and discriminate fourteen different bacteria in water and in human urine by pattern-based fluorescence recognition; the AMP-PPE complexes bind differentially to the components of bacterial surfaces. The bacterial species and strains form clusters according to staining properties (Gram-positive and Gram-negative) or genetic similarity (genus, species, and strain). The identification and data treatment is performed by pattern evaluation with linear discriminant analysis (LDA) of the collected fluorescence intensity data.

A Simple Optoelectronic Tongue Discriminates Amino Acids.

A self-assembled nine-element optoelectronic tongue consisting of a positively charged water-soluble poly(para-phenyleneethynylene) and three metal ions (Fe2+ , Co2+ , and Cu2+ ) at three different pH values (7, 10, and 13) discriminates all of the 20 natural amino acids in water. Unknown identification was not ideal. Addition of a highly positively charged green fluorescent protein in the presence of Fe2+ , Co2+ , and Cu2+ increased the unknown identification to above 86 %. Linear discriminant analysis (LDA) orders the responses according to the amino acid type, that is, hydrophobic, polar, anionic, or cationic.

Discrimination of Saccharides by a Simple Array.

We report the development of a two-component probe system as fluorescence turn-on assay of simple saccharides. The quenching of an anionic conjugated water-soluble polymer by a cationic quencher has been reported previously. Three different boronic acid functionalized benzyl viologens and three conjugated polymers of the poly(aryleneethynylene) type form nine non-fluorescent complexes. This small library discriminates nine different simple saccharides in aqueous solutions by fluorescence turn-on in a displacement assay. The saccharides can be discriminated and identified with this simple system.

Poly(p-phenyleneethynylene)-based tongues discriminate fruit juices.

We describe a simple optoelectronic tongue, consisting of a positively charged, fluorescent poly(para-phenyleneethynylene), P2, that reacts to fruit juices, when employed at three different pH-values (pH 3, 7, 13). This minimal tongue identifies and discriminates 14 different commercially available apple juices, 6 different grape juices and 5 different black currant juices from each other. A similar, negatively charged fluorescent polymer, P1, also achieved discrimination, but the analyte concentration had to be increased by a factor of 50. A mixture of black currant juice and red grape juice is identified as red grape juice, for specific combinations of grape and black currant juices. A mixture of red and green grape juice passes as red grape juice in our sensing system when it contains more than 70% of red grape juice. The data were obtained by fluorescence quenching of the conjugated polymers and processed by linear discriminant analysis of the collected data.

Truxene-Based Hyperbranched Conjugated Polymers: Fluorescent Micelles Detect Explosives in Water.

We report two hyperbranched conjugated polymers (HCP) with truxene units as core and 1,4-didodecyl-2,5-diethynylbenzene as well as 1,4-bis(dodecyloxy)-2,5-diethynylbenzene as comonomers. Two analogous poly(para-phenyleneethynylene)s (PPE) are also prepared as comparison to demonstrate the difference between the truxene and the phenyl moieties in their optical properties and their sensing performance. The four polymers are tested for nitroaromatic analytes and display different fluorescence quenching responses. The quenching efficiencies are dependent upon the spectral overlap between the absorbance of the analyte and the emission of the fluorescent polymer. Optical fingerprints are obtained, based on the unique response patterns of the analytes toward the polymers. With this small sensor array, one can distinguish nine nitroaromatic analytes with 100% accuracy. The amphiphilic polymer F127 (a polyethylene glycol-polypropylene glycol block copolymer) carries the hydrophobic HCPs and self-assembles into micelles in water, forming highly fluorescent HCP micelles. The micelle-bound conjugated polymers detect nitroaromatic analytes effectively in water and show an increased sensitivity compared to the sensing of nitroaromatics in organic solvents. The nitroarenes are also discriminated in water using this four-element chemical tongue.

Poly(aryleneethynylene) Tongue That Identifies Nonsteroidal Anti-Inflammatory Drugs in Water: A Test Case for Combating Counterfeit Drugs.

We report a sensor array composed of a highly fluorescent positively charged poly(para-phenyleneethynylene) P1 and its complex C with a negatively charged pyridine-containing poly(para-aryleneethynylene) P2 (quencher) at pH 10 and pH 13; a sensor field composed of four elements, P1 (pH 10), P1 (pH 13), C (pH 10), and C (pH 13), results. The elements of this small sensor field experience either fluorescence turn on or fluorescence quenching upon exposure toward nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, ibuprofen, diclofenac, or naproxen. The combined responses of the sensor field are analyzed by linear discriminant analysis (LDA). All of the NSAIDs were identified and discriminated, and the sensing mechanism, hydrophobic versus electrostatic, was discussed.

Water-Soluble Poly(p-aryleneethynylene)s: A Sensor Array Discriminates Aromatic Carboxylic Acids.

A chemical tongue consisting of 11 elements (four poly(p-aryleneethynylene)s (PAE) at pH 7 and pH 13, and seven electrostatic complexes formed from oppositely charged poly(p-aryleneethynylene)s at pH 7) discriminate 21 benzoic and phenylacetic acid derivatives in aqueous solution. The mechanism of discrimination is the fluorescence modulation of the PAEs, leading to quenching or fluorescence turn-on. The PAEs alone at both pH values and the tongue, consisting of the complexes only, discriminate the 21 acids with 92% (PAEs at pH 7), 95% (PAEs at pH 13), and 99% (complexes at pH 7) reliability after linear discriminant analysis (LDA). A sensor field with all 14 elements, according to LDA, discriminates all of the 21 acids with 100% accuracy.