Biosensing Elements Using Biologically Active Sol Gel Thin Films

The potential use of sol-gel-based materials as sensing elements has made these materials the subject of intensive study (27,28). Although it is possible to use monoliths, for biosensing applications, the use of thin films is preferred. The primary reason is that thin films have a reduced diffusion length for the target analyte, and, therefore, there is a greatly reduced response time, because diffusion distance varies with i12. The sol-gel matrix has an interconnected network of pores and...

References

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Atomic Force Microscopy Data

We employed three types of atomic force microscopy (AFM) data collection. The first type consisted of images of 200 nm to 1 mm, such as the one in Fig. 2, on which the protein molecules, 13 nm in size were clearly detectable. Calibration of the microscope was verified by determining the spacing of molecules along a densely, packed direction in the lattice and the thickness of the top crystalline layer. As Fig. 2 reveals, the respective numbers for one of the systems, used for the studies...

Biomolecular Templated NW Assembly

The steady trend in the electronics industry toward components having ever-smaller dimensions has stimulated the development of alternative bottom-up fabrication technologies to compete with conventional micro- and nano- lithography, which are expected to become extremely expensive as the feature sizes of future electronic circuits approach the limits of optical lithography (112). Bottom-up approaches, which rely on self-assembly (or self-organization) that often utilizes biological molecules,...

SERS as a Tool for Detection of Single Molecules

There have been several reports of single-molecule detection using SERS in recent years 4-7,113,136,137 . A critical factor in these milestone studies has been the development of exceptional SERS substrates. Most of the reports of single-molecule SERS detection have involved the use of metal colloids in suspensions. For example, Kneipp et al. demonstrated single-molecule detection of crystal violet in both silver 5,6 and colloid suspensions 7 . In these studies, an effective cross-section of...

Nsom Sers Probes

NSOM is a methodology for obtaining subwavelength resolution 20-200 nm with the spectroscopic information afforded by conventional optical spectro- scopic techniques 131,132 . The high spatial resolution of NSOM permits spectroscopic studies of individual biomolecules in high-density systems such as encountered in in vivo experiments 8,133,134 . In this respect, NSOM combined with a Raman microscope is particularly attractive. So far, this novel scanning probe technique has been restricted to...

With Microfluidics Chip Based Protein Mobility Shift

Electrophoretic mobility shift analysis EMSA is a well-characterized and widely employed technique for the analysis of protein-DNA interaction and of transcription factor combinatorics. As currently implemented, EMSA generally involves the use of radiolabeled DNA and PAGE. We have noted 20 that this technique could be effectively implemented with microfluidics chips designed for the separation of DNA fragments. To accomplish this, samples were run on a 2100 Bioanalyzer Agilent using a DNA 500...

Protein Structure The Basic Building Blocks

Proteins are long chains of molecules consisting of polymers assembled from a large number of amino acids like beads on a necklace. The sequence of the amino acids in the polymer backbone is the primary structure of any given protein. There are 20 normal amino acids. Typical polypeptide chains contain about 100 to 600 amino acid molecules and have a molecular weight of about 15,000 to 70,000. Since amino acids have hydrophilic, hydrophobic, and amphilic groups, in an aqueous environment they...

Development of Solid SERS Substrates Based on Metallic Nanostructures

In addition to immobilized colloids, researchers have developed a variety of solid surface-based SERS substrates that are produced entirely from solid materials, as depicted schematically in Fig. 1. In contrast to immobilized colloids, the solid SERS-based probes described subsequently exhibit a high degree of reproducibility. In addition, nanoshells with a dielectric core and a metallic shell e.g., Au SiO2 , or a metallic core and a dielectric shell e.g., Au core SiO2 shell , or a metallic...

SERS Gene Probes

There has been a great deal of interest in the development of optical techniques for genomics analysis such as nonradioactive DNA probes for use in biomedical diagnostics, pathogen detection, gene identification, gene mapping, and DNA sequencing. Hybridization of a nucleic acid probe to DNA biotargets e.g., gene sequences, bacteria, viral DNA permits a very high degree of accuracy in identifying DNA sequences complementary to that probe. The possibility of using SERS for low-level detection of...