Smart Nanomaterials for Sensor Application

The domain of biology has greatly been benefited by advances in other sciences leading to new levels of sensitivity, precision and resolution in biomolecular detection. The key driving force is the complementary length scale between biological structures that range from the 10's of nanometers (proteins, DNA, viruses) to the micron scale (cells and cellular assemblies) and capabilities of nanosystems to manipulate and control such feature sizes within our environment. Progress and development in biosensor development will inevitably focus upon the technology of the nanomaterials that promise to solve the biocompatibility and biofouling problems. The biosensors are integrated with new technologies in molecular biology, micro-fluidics, and smart nanomaterials, have applications in agricultural production, food processing, and environmental monitoring for rapid, specific, sensitive, inexpensive, in-field, on-line and/or real-time detection of pesticides, antibiotics, pathogens, toxins, proteins, microbes, plants, animals, foods, soil, air, and water. Thus, biosensors are excellent analytical tools for pollution monitoring, by which implementation of legislative provisions to safeguard our biosphere could be made effectively plausible. The current trends and challenges with smart nanomaterials for various applications have been the focuse in this chapter that pertains to biosensor development, bionanoelectronics, nanotechnology, biotechnology and miniaturization. All these growing areas will have a remarkable influence on the development of new ultra biosensing devices to resolve the severe pollution problems in the future that not only challenge the human health but also affect adversely other various comforts to living entities.

A new emerging field that combines nanoscale materials and biosensor technology is receiving increased attention. Nanostructures have been used to achieve direct wiring of enzymes to electrode surfaces, to promote electrochemical reactions, impose nano barcodes on biomaterials, and amplify the signal from biorecognition events. NP-based sensors have found wide spread applications in the environmental and medical applications for their sensitivity, specificity, rapidity, simplicity, and cost-effectiveness.

The aim of this chapter, without pretending to being exhaustive, is mainly to review recent important achievements about metal nanoparticles preparation, their bio modification and the new applications for protein detections by means of a set of selected recent publications.

This chapter focuses on recent developments in the construction of optical sensors based on intelligent molecularly imprinted nanomaterials. The first two parts review the general principles in the development of molecularly imprinted polymer (MIP)-based optical sensors. Four different ways to transform the binding events into measurable optical signals are discussed. In the third part, nanosized MIP materials are classified as nanoparticles (including core-shell nanoparticles), nanofibres/nanowires/ nanotubes and nanofilms. The principle, analytical properties and applications of recently reported optical sensors based on above three different nano-MIP formats are all reviewed in detail. Finally, some of the remaining unsolved issues to the nano-MIP-based optical sensors are briefly discussed for further development of the field.

This review discusses the various available controlled release products for contraception in women as well as elaborates about the thermosensitive polymers, their characterization and application for controlled delivery of contraceptive hormones. The thermosensitive polymers are free flowing solutions in water at room temperature and turn into gel at body temperature and deliver the incorporated hormones at controlled rate for longer duration after a single subcutaneous injection. These polymers are biodegradable, biocompatible, and hold a great promise for prolonged delivery of contraceptive hormones.

A nanosensor is a sensor that is built on the nanoscale, whose purpose is mainly to obtain data on the atomic scale and transfer it into data that can be easily analyzed. Nanosensors have a wide application in the fields of environmental protection, biotechnology, medical diagnostics, drug screening, food safety and security. This review is an attempt to give an overview on different types of nanosensors based on carbon nanotubes, metal and metal oxide naoparticles and their application in environmental and biomedical fields. Due to the increased gas sensing properties, metal oxide based nanosensors were found to be potential candidates for NOx, ethanol, ammonia and ozone sensing applications.

Abscisic Acid (ABA) is a vital phytohormone that regulates plant elongation, fruit ripening and senescence. It also plays an important role in plant responses to environmental stress and pathogens. In this work, self-assembled ABA was utilized as template for the growth of CdSe nanoparticles. The formed assemblies were functionalized with an organic linker (ethylene diamine) to enhance the growth of the CdSe nanoparticles on the surface of the nanofibers. The nanocomposites formed were analyzed by microscopic and spectroscopic methods. It was observed that the formation of quantum dots was promoted under mild conditions, leading to the formation of uniform nanofibers coated with CdSe nanoparticles. Further, the nanocomposites were utilized for targeting HeLa cells. We believe that such nanomaterials may lead to the development of a new family of nanomaterials for bioimaging and cancer cell targeting, as well as a host of optoelectronic applications.

In this work, a two phase hydrogel was prepared by physically imbedding a xerogel in the core of a hydrogel that was subsequently freeze thawed. The outer hydrogel was prepared by freeze thawing poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) while the xerogels were prepared by UV polymerization of 1-vinyl-2-pyrrolidinone (NVP), acrylic acid (AA) and various percentages of an Active Pharmaceutical Ingredient (API). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) confirmed that hydrogen bonding had occurred between the constituents of the two phase hydrogels, while swelling experiments in distilled water indicated that the swelling of the gels is temperature dependent. The rheological studies confirmed that, by incorporating PAA into the two phase hydrogel system the strength increased significantly. However, at temperatures under the same nominal force the hydrogels were observed to lose their physical structure. Thermal analysis suggested that the incorporation of API into the xerogel reduced the Tg by approximately 13 °C, thus suggesting that the API acts as a plastcizer within the xerogel matrix. In all cases, drug dissolution showed that the API was released at a slower rate from hydrogels that contained poly (acrylic acid).

Since the discovery of Carbon Nanotubes (CNTs) by Iijima in 1991[1, 2], there has been an explosion of research into the physical and chemical properties of this novel material. CNT based biosensors can play an important role in amperometric, immunosensor and nucleic-acid sensing devices, e.g. for detection of life threatening biological agents in time of war or in terrorist attacks, saving life and money for the NHS. CNTs offer unique advantages in several areas, like high surfacevolume ratio, high electrical conductivity, chemical stability and strong mechanical strength, and CNT based sensors generally have higher sensitivities and lower detection limit than conventional ones. In this review, recent advances in biosensors utilising carbon nanotubes and carbon nanotube fibres will be discussed. The synthesis methods, nanostructure approaches and current developments in biosensors using CNTs will be introduced in the first part. In the second part, the synthesis methods and up-to-date progress in CNT fibre biosensors will be reviewed. Finally, we briefly outline some exciting applications for CNT and CNT fibres which are being targeted. By harnessing the continual advancements in micro and nano- technology, the functionality and capability of CNT-based biosensors will be enhanced, thus expanding and enriching the possible applications that can be delivered by these devices.

Biosensors are devices which comprise of a biological recognition element and a transducer that is a physicochemical detector system. In other words, a biosensor is a sophisticated tool that combines a biological component; a bioreceptor, with a physicochemical detector component; the transducer, for the purpose of detection of an analyte. The transducer converts the information into a measurable effect such as an electric signal which can be measured and quantified. The sensitivity of biosensors can be improved and enhanced by changing the nano material in the construction. This field of research is fast developing. A conceptual background of biosensors based on selected Gold nanoparticles, their properties, synthesis, characterization and their associated uses has been described in this chapter.

Nanowires, Nanorods and Nanotubes are well-known monodimensional (1D) nanostructures. They exhibit a very high surface to volume ratio as well as unique magnetic and electrical properties which make them ideal candidates for new and innovative sensing devices. One of the key aspects in new biosensor developments is the alignment of monodimensional nanostructures that can be obtained by employing Langmuir Blodgett techniques as well as electrical and magnetic external fields. There recently have been many successful applications of 1D nanostructures in high performance sensors, such as field biomedical sensors that are able to detect very low concentrations of DNA and novel gas sensors for the detection of ultra-low concentration of toxic gases. The well-improved sensors employing 1D-nanostructures have a profound impact on healthcare and safety, thereby playing a more and more important role in the near future.