Abstract
Within the last 18 months there has been a profound change in the style of robotics available to the HTS community. Linear robotic system have entered the market and enable faster throughput and an industrial style approach to drug discovery screening (Figure 1; 1,2 ). Such systems are quite different from the “robo-centric” style of automation, which has existed in this field for the last ten to fifteen years(1,2,3,4,5). Vendors supplying these styles of robotics now include Zymark (Hopkinton, MA), CCS Packard (Meriden, CT), Jenoptik (Jena, Germany???), and Titertek (Huntsville, AL).
The Zymark Allegro - one of the earliest entries into the arena of modular linear microplate processing systems.
These systems have several advantages over “robo-centric” track-based robotics. Some advantages include:
extremely high throughput attributable to parallel processing of microplates
simplified software as scheduling is not needed
a given plate is processed serially easingserial processing of microplates which eases the transition of manual assays to automated assays
a hardware approach, which in some cases (e.g. Allegro™), provides complete modularity with embedded intelligence
However, until recently there have been some disadvantages of using these style of robotics for certain applications. For example, systems such as the CCS Packard PlateTrak™ (Meriden, CT) and the Titertek MAP™ (Huntsville, AL) do not allow physical reorganization of the module/device order. Furthermore the integration of an end user's workstation of choice (e.g. pipetter) is not possible. The integration of detectors, or microplate readers, to these systems has not been standard and has limited these systems for complete assay automation. In addition, there are no capabilities for incubating plates at environmental conditions other than room temperature. The plates are stored in stackers which make it difficult to provide uniform assay time history and random microplate access. However, these two types of systems have provided extremely strong solutions for the niches of plate preparation and partial automation of an assay.
The Allegro™, manufactured by Zymark Corporation, (Hopkinton, MA), does not have limitations on using differentthe modular workstations configuration, type or manufacturerat given modules and is designed to completely automate an assay procedure - from plate preparation to reading and, data organization. It also provides the ability to control temperature, humidity, and CO2 at each step of the process. However, the first version of Allegro for UHTS had the drawback of requiring repeated hardware modules if a similar step was performed downstream (e.g. if two pipetting steps were required, two pipetters would exist in the chain of modules) to achieve a microplate per minute throughput. This resulteds in systems that weare very large (only true for heterogeneous assays, not homogeneous assays) and relatively expensive. However, thise type of systemproduct has been very strong in filling the niche for those who required complete flexible assay automation in a UHTS mode (<1000 plates/day). And according to published results by current users, .the system has been successfully validated running such assays as: ELISA, DELFIA, SPA, kinase, and reporter gene. 6,7
Due to the points discussed in the above section traditional “robo-centric” HTS systems have continued to hold strong positions in the niche of HTS (but not UHTS) assays. Examples of these types of systems include Beckman-SAGIAN Core Systems™ (Fullerton, CA), Zymark Virtuoso™, Tecan TRAC™ Systems (Hombrechtikon, Switzerland) and SCITEC integrated systems (Lausanne, Switzerland). In particular, these types of solutions have offered cost advantages when implemented for heterogeneous assays. This niche remains the most common integrated robotic application in the pharmaceutical and biotechnology industry. However, the Zymark Allegro Combo™ now provides a modular linear based approach which directly competes with the flexibility and price range of integrated “robo-centric” systems.
Although both types of Allegro systems use the same hardware, Tthe difference between the original Allegro™ and Allegro Combo™ is the ability of the later to pass microplates both forwards and backwards along a chain of modules. This eliminates the need for repeating modules in systems implemeneted for such heterogeneous assays such as ELISA (Figure 2). Therefore system size and cost is reduced to be highly competitive with “robo-centric” systems. Despite the capability for bi-directional microplate movement, Allegro Combo™ retains most of the advantages of assembly line style automation. These include: no need for complex scheduling software;, intelligent,t truly- independent, re-configurable modules;, higher throughput (although not UHTS); and the potential for use in UHTS modes. The only compromise of an Allegro Combo™ compared with the original Allegro is that if microplate “passback mode”, or looping, is used the system cannot run at UHTS rates. However, as discussed above, very few companies aim to process 1000 microplates per day. In an Allegro Combo™ system, such as depicted in Figure 2, throughput may be of the order of 1 microplate per 3 minutes (about the same as most well configured “robo-centric” systems). This is approximately 3 times slower than an Allegro™ running in UHTS mode - because of the need to loop back three times. As the multiple robotic arms in an Allegro™ system are not the rate limiting step for microplate movement, throughput relative to UHTS mode will almost directly correlate to the number of “passback” loops.
Allegro Combo™ has the ability to pass microplates backwards and forwards amongst a chain of re-configurable modules. This reduces system size and cost. An example module configuration is shown for an ELISA style assay requiring 3 reagent addition, wash and incubation steps. The Allegro™ version requires 13 modules, whereas the Allegro Combo™ version requires only 7 modules.
SUMMARY
Until relatively recently, “robo-centric” track based robotics provided the only solution to fully automating HTS assays. In early 1998 several “assembly line style” robotic systems for HTS became available. These new approaches to HTS robotics offer numerous advantages over “robo-centric” systems. Among this group of linear systems, only the Zymark Allegro™ provided complete total and flexible assay automation enabling microplate processing, reading and data organization for UHTS. However, compared with “robo-centric” systems, this platform is costly and large in size when implemented for heterogeneous assay applications. More recently, a new version of the Allegro™ has been released, the Allegro Combo™. Allegro Combo™, which uses the same hardware as Allegro UHTS, enables bi-directional microplate passing, and creates a linear system approach which retains many of the advantages of this style of robotics at aa reduced cost and size. Allegro Combo™ now provides a powerful approach which occupies the same size, flexibility and cost niche as traditional “robo-centric” systems.
Zymark was one of Jason Armstrong, Ph.D.'s consulting clients over the last few years, as was Beckman (also mentioned in the article), and other suppliers of robotics for the HTS industry. Much of his time in the last 2 years has been devoted to consulting with pharmaceutical and biotech companies for HTS and robotics.