Nanomaterials in fluorescence-based biosensing

Abstract

Fluorescence-based detection is the most common method utilized in biosensing because of its high sensitivity, simplicity, and diversity. In the era of nanotechnology, nanomaterials are starting to replace traditional organic dyes as detection labels because they offer superior optical properties, such as brighter fluorescence, wider selections of excitation and emission wavelengths, higher photostability, etc. Their size-or shape-controllable optical characteristics also facilitate the selection of diverse probes for higher assay throughput. Furthermore, the nanostructure can provide a solid support for sensing assays with multiple probe molecules attached to each nanostructure, simplifying assay design and increasing the labeling ratio for higher sensitivity. The current review summarizes the applications of nanomaterialsincluding quantum dots, metal nanoparticles, and silica nanoparticles-in biosensing using detection techniques such as fluorescence, fluorescence resonance energy transfer (FRET), fluorescence lifetime measurement, and multiphoton microscopy. The advantages nanomaterials bring to the field of biosensing are discussed. The review also points out the importance of analytical separations in the preparation of nanomaterials with fine optical and physical properties for biosensing. In conclusion, nanotechnology provides a great opportunity to analytical chemists to develop better sensing strategies, but also relies on modern analytical techniques to pave its way to practical applications.Keywords Nanomaterials . Quantum dots . Gold nanoparticle . Silica nanoparticle . Fluorescence . FRET . Biosensing OverviewSensitive detection of target analytes present at trace levels in biological samples often requires the labeling of reporter molecules with fluorescent dyes, because fluorescence detection is by far the dominant detection method in the field of sensing technology, due to its simplicity, the convenience of transducing the optical signal, the availability of organic dyes with diverse spectral properties, and the rapid advances made in optical imaging. However, it can be difficult to obtain a low detection limit in fluorescence detection due to the limited extinction coefficients or quantum yields of organic dyes and the low dye-toreporter molecule labeling ratio. The recent explosion of nanotechnology, leading to the development of materials with submicron-sized dimensions and unique optical properties, has opened up new horizons for fluorescence detection. Nanomaterials can be made from both inorganic and organic materials and are less than 100 nm in length

Simultaneous Detection of Multi-DNAs and Antigens Based on Self-Assembly of Quantum Dots and Carbon Nanotubes

“…Compared with organic fluorophores, QDs have similar quantum yields but extinction coefficients that are 10∼50 times larger, and much-reduced photobleaching rates. The overall effect is that QDs have 10∼20 times brighter fluorescence and about 100∼200 times better photostability Zhong, 2009). For applications in biomedical studies, QDs should be water soluble, which can be achieved in two ways: the first is to directly synthesize QDs in aqueous solution; the other is to synthesize QDs in organic solvents and then transfer the hydrophobic QDs into aqueous solution, for example, by ligand exchange or polymer coating .…”

“…With the development of nanoscience and nanotechnology, a series of novel nanomaterials with controlled size and morphologies are being fabricated, their novel properties are being gradually discovered with difference from their corresponding bulk materials, and the applications of nanomaterials in biosensors have also made great advances (Jianrong et al, 2004;Kumar, 2007;Pandey et al, 2008). Nanomaterials can be made from both inorganic and organic materials and are less than 100 nm in length along www.intechopen.com Carbon Nanotubes -Growth and Applications 242 at least one dimension (Asefa et al, 2009;Zhong, 2009). This small size scale leads to large surface areas and unique size-related optical properties.…”

“…Therefore, the position of the absorption as well as the luminescence peaks can be finetuned by controlling the particle size and the size distribution during synthesis, generating a large group of "fluorophores" with diverse optical properties (Nirmal and Brus, 1999;Pradhan et al, 2005). The size-or shape-controllable optical characteristics of nanomaterials facilitate the selection of diverse probes for higher throughput assay (Zhong, 2009). Furthermore, the nanostructure can provide a substrate support for sensing assays with multiple probe molecules attached to each nanostructure, simplifying assay design and increasing the labeling ratio for higher sensitivity (Kumar, 2007).…”

Interaction of polymer-coated silicon nanocrystals with lipid bilayers and surfactant interfaces

“…Fluorescent nanoparticles, in particular, offer a unique platform for labeling and detection across a range of biologically relevant settings [2], with perhaps the most highly touted class of such materials being the semiconductor nanocrystals [3,4].…”

Microfluidic Fabrication of Colloidal Nanomaterials-Encapsulated Microcapsules for Biomolecular Sensing

“…16 To achieve specificity in these responses, nanomaterials have been conjugated to ligands that provide specific binding of analytes. Upon target binding, the nanosensors generate 15,17 or amplify 18,19 an optical responses. Some examples of previously studied optical sensing methods include fluorescence, 17 luminescence, 20 and surface-enhanced Raman spectroscopy (SERS) 19 as well as surface plasmon resonance (SPR).…”