Multi-pathogen biosensors that take advantage of sandwich immunoassay detection schemes and utilize conventional fluorescent dye reporter molecules are difficult to make into extremely compact and autonomous packages. The development of a multi-pathogen, immunoassay-based, fiber optic detector that utilizes varying sized fluorescent semiconductor quantum dots (QDs) as the reporter labels has the potential to overcome these problems. In order to develop such a quantum dot-based biosensor, it is essential to demonstrate that QDs can be attached to antibody proteins, such that the specificity of the antibody is maintained. We have been involved in efforts to develop a reproducible method for attaching QDs to antibodies for use in biodetection applications. We have synthesized CdSe/ZnS core-shell QDs of differing size, functionalized their surfaces with several types of organic groups for water solubility, and covalently attached these functionalized QDs to rabbit anti-ovalbumin antibody protein. We also demonstrated that these labeled antibodies exhibit selective binding to ovalbumin antigen. We characterized the QDs at each step in the overall synthesis by UV-VIS absorption spectroscopy and by picosecond (psec) transient photoluminescence (TPL) spectroscopy. TPL spectroscopy measurements indicate that QD lifetime depends on the size of the QD, the intensity of the optical excitation source, and whether or not they are functionalized and conjugated to antibodies. We describe details of these experiments and discuss the impact of our results on our biosensor development program.
Advanced materials are being designed and tested for use on ball bearings that have wide-ranging applications in almost any type of spacecraft. There has been considerable interest in 'hard' or wear-resistant coatings for protecting steel surfaces present in bearing components. Titanium carbide (TiC) has received serious consideration as a wear-resistant coating material that could be suitable for use in such applications. At present, the commercially available process for the deposition of TiC involves heating the steel substrates to fairly high temperatures. High-temperature coating deposition is not desirable for applications involving steel substrates as it results in a softening of the steels. This further necessitates post-deposition heat- treatments for re-hardening the steel and re-polishing the coating. This paper will describe the use of Pulsed Laser Deposition (PLD) to deposit high-quality thin films of TiC on bearing steels at room temperature. Such a process eliminates the problems associated with high temperature deposition, and the costs and complexities involved in the post-deposition heat treatment of steels. To develop an understanding of the deposition process, the plasma generated by laser ablation has been investigated using time-resolved emission spectroscopy. The PLD of TiC films on bearing steels, the material properties of these films, and the spectroscopy of the ablated plume will be discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.