1. Technical Field
The invention relates generally to three-dimensional physical models of complex structures, and more particularly to three-dimensional physical models of molecular structures and methods of manufacturing such models.
2. Background Prior Art
The study of molecular structure and function is at the core of modern biology, and shapes much of biological research. Images of newly solved structures are appearing at an ever increasingly rate in science journals weekly and the rate is increasing, as structural biology becomes a mainstream science. At the same time that understanding of molecular structures has increased, methods to model and communicate understanding of these structures has not.
A number of different types of molecular model construction are known and used to represent molecular structures and to study the interaction between a large molecule, such as an enzyme, and its substrate. Many of the models currently in use are the well known. For example, it is known to use ball and stick models in which balls representing atoms are connected by rigid or flexible connectors representing chemical bonds. Using such models it is possible by tedious manual construction to assemble space filling representations of complex molecules.
Other known molecular models currently in use include space filling individual components fabricated of plastic or other rigid material representing the space filling nature of individual molecular structures. These models must also be individually assembled from construction units representing single atoms, involving tedious manual manipulation by highly skilled personnel. One reason why skilled personnel are sometimes needed to assemble molecular structure representations from known modeling kits is that the modeling kits include many parts that can be assembled in a variety of arrangements. Due to the flexibility of the kit a model can be assembled incorrectly, thus inaccurately representing the structure of the subject molecule. A skilled person having knowledge of the subject structure""s configuration is therefore needed to accurately assemble the model.
Information technology also provides one type of readily available computer-generated, virtual model of complex structures through the generation of interactive computer images. Although the image created on the computer screen is two-dimensional, various shading, depth cueing and kinetic depth effects can produce an image that takes on three-dimensional character when the model appears to rotate on the screen. Although these computer visualization programs were originally developed for UNIX-based computer workstations, versions now exist for use in desktop computer (PC or Mac) environments. Once such program, RasMol, is publicly available software. An extensive molecular structure database exists at the Protein Data Bank web site (http//www.rcsb.org/pdb) which can be down-loaded and used with RasMol, or in the RasMol-based Chime software using the down-loaded data permits virtual modeling of the molecular structures.
The following prior art references disclose a variety of model constructions and techniques used for the modeling of complex structures, such as molecular models.
Although computer-generated images can be used by experienced users to view molecular structure in great detail, these virtual models are often unavailable in classrooms and other facilities without computers. Moreover, even when such virtual modeling apparatus is available, the virtual models can be unappreciated by those who have no previous experience with either the modeling software or the molecular structure. For these individuals, physical models provide a tangible object to which users can relate in a tactile manner. In general, a three-dimensional model of complex structures assists in gaining a more complete understanding of the functional consequences of the three-dimensional structure.
Also, physical models are a necessary complement to, not a substitute for, computer-aided visualization. While interactive computer-generated images are much superior to static, two-dimensional pictures, this technology does not naturally facilitate group discussion. Only one person controls the computer xe2x80x9cmodelxe2x80x9d, and it is often difficult for inexperienced students to visualize the three-dimensional character of these computer-generated images. However, a physical model can be thought of as the ideal portable, three-dimensional, graphical display. Unlike a computer-generated image, it is always xe2x80x9conxe2x80x9d; and be shared among multiple users quickly and easily. Thus there is a need for accurate, affordable physical models of biological structures.
In one embodiment, the invention provides an affordable, easy-to-use, accurate three-dimensional model of a complex structure, such as a molecule or chain of molecules, that can be used to study the structure and its function, as well as a method to manufacture the three-dimensional model. More particularly, in one embodiment, the invention provides a three-dimensional model of a complex structure including a backbone representation of a series of predetermined elements interconnected by representations of bonds extending between the predetermined elements.
In another aspect, the invention provides a method of making a three-dimensional model through the application of rapid prototyping technology, particularly Solid Freeform Fabrication (SFF) techniques. The use of such techniques is particularly well-suited to the production of physical models of the complex geometry found in molecular structures. The complex geometry found in three-dimensional protein structures precludes the use of subtractive manufacturing methods as found in traditional numerical control machining. However, these complex structures can be produced by the additive manufacturing processes employed by SFF prototyping technologies.
Although physical models produced by rapid prototyping technologies have all the properties required to be useful as instructional aids in science education, the use of rapid prototyping technologies alone is not feasible because such techniques are too slow and costly to produce molecular models in large numbers.
Accordingly, in another embodiment, the invention provides a method of manufacturing a model of a complex structure, such as a molecular model, including steps that afford use of relatively inexpensive processes such as injection molding. In particular, the invention also provides a method of making a three-dimensional model including the use of rapid prototyping techniques to divide the model into a series of segments that can be more easily manufactured than the model as a whole and that can be assembled by persons without any particular knowledge of the molecular structure and without any particular or special modeling skills.
Another aspect of the invention is the provision of a model including a plurality of model elements or segments that each have interconnecting fittings which are configured to engage only the appropriate adjacent segments, i.e., the segments fit together in only one way, so that the model as a whole can be constructed without foreknowledge of the modeled structure and without any special training. The configurations of the segments and the interconnecting fittings are also amenable to injection molding.
The invention thus provides several advantages. First, the invention provides a model of a complex structure, such as a molecular structure, divided into a series of short segments each of which possess a simple geometry. The model segments afford production by injection molding and have uniquely configured connectors built into the ends of the segments, allowing contiguous segments to be joined together to create the model. The invention also provides a method of making the model in an accurate, cost effective manner, and a method for representing covalent bonds which act in the molecular structure by the use of structural elements initially formed through the use of rapid prototyping techniques.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.