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Recent developments in plasmonic nanostructures have great importance in improving the sensing characteristics of optical sensors. Plasmonic nanostructures are widely used to develop optical nanobiosensors for quantitative detection of bio-species and their analysis. This may include medical diagnostics, food quality, and environmental monitoring. In this chapter, we demonstrate the basics of plasmonic nanostructured materials and their application in biosensors on the basis of surface plasmon response and localized plasmon response principles. Also we describe the integration of plasmonic nanostructures with fiber-optic technology for biosensing applications.

We have focused on the fundamentals and applications of biosensors in the preceding Chapters 1–9 Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 . The key challenges pertaining to the fabrication of point-of-care biosensors are that they should be easy to use, be handheld, be fast in analysis, be affordable, and have enhanced availability. The market for biosensors except for glucose sensors is slightly incremental with a low success rate. In this chapter, we discuss the potential issues in biosensors for commercialization with future prospects for development and end up with conclusions.

With remarkable advantages of nanostructured materials, there is a tremendous growth in development of DNA biochip–based devices for point-of-care applications. DNA chips have attracted significant interest as they enable miniaturization, fast analysis, and integration with biochemical assays. Coupled with high sensitivity, selectivity, and low sample volume, the integration of nanostructures into DNA biochips offer several features such as low-cost diagnostic tests, quick analysis, and simplicity and reduced assay times. In this chapter, we focus on the application of the nanostructured materials toward development of DNA biochips, microarrays, and RNA biosensors. Biochips are known as DNA chips, protein chips, and microfluidic chips. We will discuss basics and fundamentals of DNA biochips, various nucleic acid biosensors including DNA, peptide nucleic acid, RNA, and aptamers. We also cover the surface functionalization of nanomaterials with DNA molecules and the importance of nanomaterials for biosensing using different techniques.

With the recent advancement of nanomaterials and nanostructured materials, the point-of-care biosensor devices have shown a potential growth to revolutionize the future personalized health care diagnostics and therapy practices. This chapter deals with the fundamentals of nanomaterials-based biosensors. The first chapter covers the brief details of nanotechnology with its types and an introduction to the synthesis of nanomaterials and their importance to construct transducers. The different components of transducers such as electrochemical, optical, piezoelectric, thermal, surface plasmon resonance, and so on for biosensors have been explained in this chapter. Various principles utilized for development of enzymatic biosensors, immunosensors, DNA, and whole-cell biosensors have been included in this chapter. Immobilization of bioreceptors is a crucial step to fabricate biosensors and their stepwise demonstration and conjugation of nanomaterials with nanomaterials have been described.

Advanced functional nanocomposite materials have been found to play a major role in the development of biomolecular devices. Chemists, biologists, physicists, and materials scientists have been showing great interest to exploit the hybrid properties of smart nanocomposite materials by assembling their inorganic, organic, and biological properties into miniaturized biomolecular devices for health care diagnostics. Besides this, hybrid nanocomposites have been predicted to have promising applications in different fields including electronics, mechanics, protective coatings, catalysis, medicine, biotechnology, etc. Efforts are continuing to make new functional hybrid materials by researchers with exciting properties in biosensor fields. In this chapter, we discuss different aspects of hybrid nanocomposites, their formation, and applications for biomolecular devices.

Polymers have been considered as insulating materials for the past 40 years. With a simple modification, polymers can conduct electricity like metals. Nanostructures of conducing polymers prepared by several methods including hard-template, soft-template, and other methods can be conjugated with bio-species for construction of biosensing devices. Biopolymeric nanostructured materials have recently received much attention in nanoscience and nanotechnology due to their unique and tunable electrochemical and optical properties. Among the various nanobiomaterials, nanostructured conducting polymers (nCPs) are getting increasing interest for the development of biosensors due to biocompatibility in cellular environments. Many nCPs have been projected to have applications in clinical diagnostics. This chapter describes the salient features of nCPs for applications in biosensors and bioimaging.

Biomaterials are natural materials that can be utilized to replace and aid the functions of a body part or a entire organ system and that which remains in contact with the living cells or tissues without inducing a toxic response. The nanostructured biomaterials are being intensely investigated for the development of both in vivo and in vitro biosensors. This chapter focuses on the biosynthesis of the various nanostructures and their applications toward development of in vivo biosensors. Several issues associated with the development of in vivo biosensors are explained in this chapter. Besides this, efforts have been made to discuss the characteristics of different nanostructured biomaterials including metallic, polymeric, composite, carbon, and ceramic for application in in vivo biosensing and bioimaging.

In recent years, nanostructured metal/metal oxides–based immunosensors have gained unprecedented growth with fast detection, high sensitivity, and portability for detection of biomolecules (enzymes, antibodies, proteins, etc.). In particular, nanostructured metal oxides–based electrochemical immunosensors offer several advantages such as enhanced loading of desired biomolecules due to their larger surface area, biocompatibility, low cost, and fast analysis. The utilization of nanostructured metals in electrochemical- and optical-based immunosensors has been exploited due to the multifunctional properties of nanostructured metals. Nanostructured metals provide multilabel amplification, high densities of captured bio-species, multiplexing capability for simultaneous measurements of multiple biomarkers via microarrays, and detection of minute concentration of desired biomolecules. In this chapter we describe details of the nanostructured metals/metal oxides for development of immunosensors.

A novel biosensor platform comprising of the functionalized sputtered rutile nanostructured titanium dioxide (nTiO2) for rapid detection of estrogenic substance (bisphenol A) has been proposed. The direct current (DC) sputtering of titanium (Ti) on glass substrate has been converted to ordered nanostructured TiO2 film via oxidation. The nanostructured TiO2 surface was functionalized with self-assembled monolayer (SAM) of 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde. The enzyme molecule, tyrosinase (Tyrs) has been covalently immobilized on the surface of APTES modified nanostructured TiO2 film. To investigate the crystalline structure and surface morphology of functionalized nTiO2/Ti electrode, the X-ray diffraction, scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy have been carried out. This impedimetric biosensor exhibits a comparable sensitivity (361.9 kΩ/µM) in a wide range of detection (0.01–1.0 µM) and a response time of 250 s for bisphenol A (BPA) monitoring. This novel manufacturing process for nTiO2 film is cheap, practical and safer for functionalization with SAM and glutaraldehyde to improve the biosensor efficacy. The strong protein absorption capability of the nTiO2 surface demonstrates an excellent electrochemical biosensor and could be useful for the detection of other phenolic compounds.