Antigen Molecules

The attachment and growth of several types of mammalian cells on fibro-nectin-coated PDMS have been reported. All cells grew at the same rate on the PDMS irrespective of its degree of cross linking, but the compatibility of the cells on the surfaces did depend on the cell type. Similar results were obtained when micropatterns of hydrophilic regions were placed on PDMS by means of a gas plasma. These modifications of the PDMS surfaces were found to increase the adhesion of fibroblast cells. On the other hand, grafting sulfobetaine onto PDMS surfaces decreases the adsorption of blood platelets.  

Geometric aspects can also be important, as illustrated by control of the spreading of mammalian cells on wavy PDMS surfaces. Wavy surfaces were generated by stretching a sheet of the elastomer, exposing it to a oxygen plasma, and the allowing it to relax. 

Another study focused on PDMS surfaces made hydrophilic by modification with hydrophobins (small, cysteine-rich and amphiphilic fungal proteins). This approach was used to pattern antigen molecules, followed by immunoassays. For example, chicken immunoglobulin G was found to be compatible with the hydrophhobin-modified PDMS. 

Some related work involved cellular interactions of collagen-immobilized PDMS surfaces, and the immobilization of antibody fragments on polymer brushes supported by silicone nanofilaments.  

---

Definition of the association (or avidity) constant for such multivalent antibody—antigen reactions must consider not only the heterogeneity of the antibodies and the antigen determinant site(s), but also an apparent additive effect of binding two antigen molecules to a single antibody. Such effects lead... 

A common application for (strept)avidin-biotin chemistry is in immunoassays. The specificity of antibody molecules provides the targeting capability to recognize and bind particular antigen molecules. If there are biotin labels on the antibody, it creates multiple sites for the binding of (strept)avidin. If (strept)avidin is in turn labeled with an enzyme, fluorophore, etc., then a very sensitive antigen detection system is created. The potential for more than one labeled (strept)avidin to become attached to each antibody through its multiple biotinylation sites is the key to dramatic increases in assay sensitivity over that obtained through the use of antibodies directly labeled with a detectable tag. 

Immunocytochemical staining with antibody-gold probes is a powerful way to detect, localize, and quantify antigen molecules in tissue sections and cells (Figure 24.3). Metabolic processes can be followed, epitope mapping of the structural characteristics of macromolecules can be... 

An ordered antibody array has also been assembled on the solid surface by a combination of Langmuir Blodgett (LB) film method and self-assembling method. An ordered monolayer of protein A is deposited on the solid surface by LB method, which is followed by self-assembling of antibody. Individual antigen molecules which are complexed with the antibody array have been quantitated selectively by atomic force microscopy (AFM). 

The high molar absorptivities and quantum yields of the large protein fluorophore phycoerythrin (240,000 Da) have been exploited in energy transfer assays. Phyco-erythrin has been used as both donor and acceptor, with several bound antigen molecules per phycoerythrin molecule/86,94) The usefulness of BPE is indicated in competitive assays for human IgG that use fluorescein-labeled antibody as donor to... 

Polyclonal antibodies are produced by injecting an antigen into an animal in the presence of an adjuvant containing bacterial lipopolysaccharides that stimulate the immune system. Serum prepared from the blood contains several different classes of antibodies that interact with different domains in the antigen molecule, each of... 

Immunoprecipitation (IP) is one of the most widely used immunochemical techniques. It involves the interaction between an antigen and its specific antibody. Antigen-antibody interactions may produce a network of many antigen molecules cross-linked by antibody molecules, which result in insolubilization and precipitation of the complex (Williams 2000). 

Among the many immunological assay methods, the enzyme-linked immunosorbent assay methods (ELISA) are the most popular methods. ELISA can detect both antigen molecules and antibody molecules with only a slight modification of the procedure. The direct-binding and sandwich methods that are used for the... 

When certain foreign chemicals (antigens) or bacteria, covered with antigenic surface components, enter the animal body, an immune response is initiated, leading to the production of antibodies or immunoglobulins. These proteins can combine non-covalently with their antigen molecules in a specific way. The antigenicity and im-... 

---