Application Molecularly Imprinted Solid Phase Extraction for Determination of Quercetin From Red Wine

Because HPLC characterization of molecularly imprinted polymers for quer-cetin has proven the existence of a substantial imprinting effect, the polymer was used as sorbent material for the solid-phase extraction of quercetin from red wine (18). The molecularly imprinted polymer enabled facile sample Fig. 3. Chromatogram of a red wine (Merlot) registered at 265 nm (2) before and (1) after MIP solid-phase extraction (1) after 1.75 mL of elution. (From ref. 18 with permission.) WVL, wavelength....

Protocols and Instrumentation

Molecular Engineering of Cytochrome b5 Cytochrome b5 is an electron carrier protein encompassing an iron proto-porphirin IX as a redox cofactor. This protein is naturally anchored onto the endoplasmic reticulum membrane of cells through a C-terminal hydrophobic amino acid sequence (Fig. 1). The globular redox domain is hydrophilic and does not interact with membranes. This domain features a high absorbancy at 413 nm for the oxidized form that shifts to 423 nm on reduction. An engineered...

Introduction

Crystallization of proteins, as any other phase transition, occurs through a combination of processes at molecular, mesoscopic, and macroscopic length scales. During phase transitions in solution, molecular-level phenomena include the interactions between the molecules that alter the free energy landscape to cause the formation of the new phase and determine the driving force for the phase transformation attachment of molecules to the new phase during growth formation of sites suitable for...

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

R., Zhou, C. W., Chapline, M. G., Peng, S., Cho, K., and Dai, H. (2000) Nanotube molecular wires as chemical sensors. Science 287, 622-625. 2. Li, J. and Ng, H. T. (2004) Carbon nanotube sensors, in Encyclopedia of Nanoscience andNanotechnology (Nalwa, H. S., ed.), American Scientific Publishers, Santa Barbara, CA, Vol. 1, 591-601. 3. Cui, Y., Wei, Q., Park, H., and Lieber, C. M. (2001) Nanowire nanosensors for highly sensitive and selective detection of biological and...

Matrix Enzyme Surface Interactions

The body of work with CK suggests that the enzyme may act as a pore template during the sol-gel process that is, the matrix forms around the enzyme during gelation. As to the mechanism of stabilizing CK using sol-gel immobilization, it is plausible to assume that there are favorable interactions between the enzyme and the silica matrix. The outer surface of CK contains more positively charged patches than negative patches, as shown by electron density calculations (24). When sol-gel silica is...

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...

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

Plasma Etching Fused Quartz

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...