Current Organic Chemistry - Volume 19, Issue 12, 2015

Sensing clinically relevant biomolecules is crucial for the detection and prevention of disease. Currently used detection methods tend to be expensive, time intensive, and specific for only one particular biomolecule of interest. Nanoparticle-based arrays using conjugated polymers have emerged as an analytical and potential clinical tool, allowing detection of a wide range of biomolecules using selective, not specific, sensor components. In this report, we highlight recent progress in nanoparticle - polymer sensor arrays in both the fundamental understanding of how the sensor arrays function as well as the detection of clinically relevant bacteria and cells.

By means of the modular construction of a large series of poly(arylene ethynylene)s (PAEs) employing Pd-promoted synthetic routes, molecular models of type A—C≡C—B-C≡C—A and B—C≡C—A—C≡C—B, and polymers of type [—C≡C—A—]n and [—C≡C—A—C≡C—B—]n carrying a variety of aminoacidic side arms, have been prepared and fully characterized towards their application as sensing materials. The introduction of different aminoacidic groups as side substituents on the conjugated backbone may allow the tuning of the recognition ability of the receptor site towards given analytes. The luminescent sensing properties of these materials towards metal ions were investigated. The flexibility of the synthetic route allows tuning of binding activity, molecular recognition and opto- and electro- properties of the materials, as well as the responses upon exposure to metal ions. All compounds showed high selectivity towards Hg(II) ions, and a signal amplification in Hg(II) detection was observed for the polymeric compound in comparison with small molecule analogues. Further functionalization of aminoacid substituted PAEs with ferrocene moieties allows the electrochemical sensing by change in the oxidation potential of Fe(II)/Fe(III) redox couple, and its dependence with the interaction of aminoacidic side arms with given analytes.

Oxacalix[n]hetarene is the sub class of calixarene in which oxygen atom replaces the methylene bridge. Oxacalix[n]hetarene compounds represent an interesting class of supramolecules/macrocycles in the last decade, and its chemistry has been elongated to include various derivatives. This review article summarizes the synthesis of oxacalix[n]hetarene compounds and their derivatives, conformational analysis as well as their applications.

The review highlights the application of Layer-by-Layer (LbL) structures for the design of chemical sensors. The first part of this review focuses on atomic and molecular layer deposition from vapor phase. In the second and third parts of the review we emphasize the formation of multilayers from solutions. LbL films and LbL prepared capsules are considered as elements of sensing systems. It is shown that LbL nanostructures can significantly increase sensitivity and selectivity of sensors and biosensors. Different materials for the multilayers’ formation, deposition techniques, and mechanisms for enhancement of the sensing properties are discussed.

Owing to their unique and indispensable physical, chemical, electrical/ electronic, and mechanical properties, graphene and conducting polymers have become attractive materials in all fields of science and technology. This mini-review provides a comprehensive summary on the cutting-edge sensor technologies based on graphene/ conducting polymer hybrid materials. In this article, we briefly mention the preparations and characteristics of graphene and conducting polymers. In addition, the expected synergistic effects resulting from the combination of graphene and conducting polymers as sensing media are addressed. Subsequently, an extensive and succinct summary on the impressive chemical and biological sensors using graphene/conducting polymer hybrid materials will be covered. A short introduction to the emerging sensors using the elegant nanocomposites will also be described. Finally, perspectives and challenges of graphene/conducting polymer sensors are outlooked. It is obvious that this article is important for understanding the current sensor technologies and offers essential information to the researchers in diverse fields.

The interest in the use of sensoring strategies using semiconductor quantum dots has been exponentially increased. During the last decades, several quantum dots of different compositions have extensively been designed for many sensoring developments. Due to their excellent properties, the use of quantum dots and their surface modification can be versatile in the sensor community. This review article describes the recent progress of the chemical and biochemical sensoring strategies using different compositions and new generations of quantum dots, carbon based quantum dots, and the challenges and opportunities they offer.

This review focuses on the recent development of graphene quantum dots (GQDs) as fluorescence probes, including their synthesis and application in metal ions detection. Because of the quantum confinement and edge effects, GQDs have exhibited unusual optical and chemical properties. Recently, various studies have been performed to tune the fluorescent properties of graphene quantum dots through doping heteroatom to the π- conjugated system or surface-functionalization. Herein, we summarize the fundamental optical properties of GQDs influenced by size/shape, zigzag site and defect density, which is of very importance for the development of novel nanodevices with novel properties. We then highlight the application of graphene quantum dot probes in fluorescent sensing of metal irons. We also discuss the current challenges and application prospects of fluorescent GQDs in metal ions sensor field.

The possibility of interacting with individual atoms in an atomically layered 2- dimensional (2D) material brings an ideal platform for highly sensitive and selective electrochemical biosensing. The discovery of graphene opened new avenues in biosensor development, and it also brought forward the possibilities of other layered materials based on sensing platforms. Other 2D atomic layers include various functional derivatives of graphene (graphene nanoribbons, graphene quantum dots, graphene oxide (GO), reduced GO, doped graphene etc.), metal chalcogenides and various inorganic 2D structures. This article reviews the recent trends in 2D layers based electrochemical biosensing, and future scope of this area. The first part of the article describes the research on graphene and its functional derivatives based on various bio-analyte sensors. This includes the graphene based enzymatic and non-enzymatic sensing possibilities. Later part of the article reviews recent developments in other 2D materials based sensing. The review concludes with a short account on the future scope of this research area and the possibilities of these sensors into clinical translation.

Electronic sensors have been considered as essential elements for chemical and biological detection in a standalone miniaturized form or in a fully integrated system. The field-effect transistor based on organic material is an emerging device that has drawn tremendous attention because of its many beneficial features such as light weight, mechanical flexibility, facile chemical modification, and low-cost processes. Given the progress in related fields-e.g., organic light emitting diodes (OLEDs), organic photovoltaics (OPVs), and organic thin film transistors (OTFTs)-the appropriate coupling of these technologies with sensors is actively expanding, with new ideas and experimental approaches. To reach the ultimate goal of high performance in terms of sensitivity, selectivity, stability, and response time, many concepts have been proposed. This review article summarizes recent research activities on chemical and biological field-effect transistors sensors based on organic and carbon materials. In particular, we highlight the different levels of performance obtained using a variety of organic semiconducting materials.

Drug of abuse or illicit drugs have become a serious health issue and global evils during the last few decades. Their detection is a significant area of research, for preventing illegal traffic and toxic effects on human health and society. Numerous analytical methods, based on diverse principles, have been developed for the detection of drugs of abuse. The core intention of present review is to pioneer the reader with the varieties of drugs of abuses (availability, formation, and use and ill-use) as well detection techniques developed and employed in the past few years. The study includes a comparative review of analytical detection techniques. Effectiveness of chemical sensors over other analytical techniques is particularly emphasized.