Self-assembled monolayer derivatization

Figure 3. Self-assembled monolayer derivatization scheme.

The Protein Profiling Biochip is composed of six chips assembled in a flow cell cassette device. Each chip provides 200 data points (200 pillars per chip) for a total of 1200 data points per cassette. Pillars are 50 p in diameter. The mesa on each pillar is covered with a self-assembled monolayer (20 to 25 A thickness) of biotin-derivatized PLL-g-PEG groups. A constant grafting ratio of 3.5 parts Lys to 1 part PEG is maintained with variable biotin-PEG content. sAV antibody is immobilized at 0.5 to 2 pmole/cm and Fab fragments at 4 pmole/cm. ... 

Self-Assembled Monolayer Films of Thiol-Derivatized Polymers... 

Two additional special cases that can be termed chemical vapor deposition are worthy of mention, since they are the vapor-phase analogues of solution techniques discussed above. These are self-assembling monolayer formation and vapor-phase surface chemical derivatization. In the former, it is necessary only to... 

FIG. 26 Schematics for creating a microscopic spot of immobilized enzymatic activity by localized derivatization of self-assembled monolayers according to (A) GOx on an patterned gold alkanethiolate layer and (B) diaphorase on alkylsilanized glass. (Part A from Ref. 21. Copyright 1997 American Chemical Society. Part B from Ref. 91. Copyright 1997 American Chemical Society.)... 

These nanometer-thick layers are easily fabricated from commercially available substances, or can at least be synthesized with relative ease [4]. The first applications of self-assembled monolayers (SAM) for biosensor use were described in the late 1980s and originally developed for Biacore instruments [5,6]. Hydroxyl-terminated long chain thiol alkanes were designed for the formation of the SAM on gold. Such layers can be activated for direct Hnkage of various molecules or further derivatized with different chemistries... 

Direct detection of a cytokine protein, recombinant human interferon-y, using an IBIS SPR sensor is presented in [60]. Several types of sensor chip coatings, including self-assembled monolayers and hydrogel-derivatized SAMs, were characterized in terms of their ability to resist non-specific adsorption from plasma. The best results with respect to plasma adsorption and surface regenerability were obtained with antibodies immobilized on the dextran-modified 11-mercaptoimdecanoic acid SAM. The detection limit for detection of human interferon-y in 1 100 diluted plasma was established at 250ngmL . ... 

Hitherto, many methods for the preparation of carbohydrate microarrays have been described, such as nitrocellulose coated slides for noncovalent immobilization of microbial polysaccharides [23], and self-assembled monolayers modified by Diels-Alder mediated coupling of cydopentadiene-derivatized oligosaccharides [24], just to name two. Unfortunately, the first method requires large polysaccharides or lipid modified sugars for the noncovalent interaction. The latter method requires the preparation of oligosaccharides bearing the sensitive cyclopentadiene moiety. 

Di Natale C., Raolesse R., Mantini A., Macagnano A., Boschi T., and D Amico A., Kelvin prove investigation of self-assembled-monolayers of thiol derivatized porphyrins interacting with volatile compounds. Sens. Actuators B, B48, 368-372, 1998. 

Z. Zhang, N. Yoshida, T. Imae, Q. Xue, M. Bai, J. Jiang, and Z. Lui (2001). A self-assembled monolayer of an alkanoic acid-derivatized porphyrin on gold surface A structural investigation by surface plasmon resonance, ultraviolet-visible, and infrared spectroscopies. J. Colloid Interf. Sci. 243, 382. 

Subsequently this molecule was applied as a self-assembled monolayer on gold. After a photochemical modification, the adsorbates were selectively derivatized to yield amino-functionalized surfaces in a simple two-step reaction. 

During the last decade the field of electrochemistry has witnessed a very fast progress on the modification of electrode surfaces. From the predominant use of random polymeric structures, prevalent in the electrode modification efforts of the late 70s and early 80s, electrochemists have learnt to control the molecular architecture of the electrode-solution interface to a degree that was clearly out of reach a decade ago. Many electrode modification methods developed recently rely on the use of thiolate self-assembled monolayers (SAMs) [1-3]. These systems offer unparalleled ease of preparation and levels of molecular organization close to those that can be reached with Langmuir-Blodgett film methods. Therefore, electrodes derivatized with unfunctionalized or functionalized alkanethiolate monolayers have been the subject of extensive research work during the last few years [4, 5]. 

Fujita K, Nakamura N, Ohno H, Leigh BS, Niki K, Gray HB, Richards JH (2004) Mimicking protein-protein electron transfer voltammetry of Pseudomonas aeruginosa azurin and the thermus thermophilus Cu-A domain at omega-derivatized self-assembled-monolayer gold electrodes. J Am Chem Soe 126 13954-13961... 

Self-assembled monolayers of an Os3(CO)s CN(CH2)3Si(OEt)3)(ft3-ri rf if-C6o) cluster on indium-tin oxide or gold surfaces have been shown to be electrochemically stable, being reducible to tetra-anionic species in their cyclic voltammograms. Further derivatization through tethering a zinc porphyrin complex to the cluster generated a high-performance photovoltaic cell with potential applications in artificial photosynthesis. ... 

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