Charged results: effective cleaning of 'disposable' pipette tips can save a company upwards of $0.5 million, but for a pipette tip cleaning system to be considered, its validity must be guaranteed. With an ARTEL MVS system, Cerionx believes they can offer that guarantee.

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In life science laboratories, automation and other related technologies have been key factors in lowering costs, increasing experimental accuracy, and condensing development and discovery timelines. However, while laboratories are eager to adopt new technologies to further streamline operations, verifying the quality of the performance of these new technologies is still essential.

Cerionx, based in Exton (PA, USA), is a company that has introduced a technology that enhances automated laboratory processes and provides users with a method that can easily-validate the effectiveness of its own technology. The company's focus enables significant reductions in automated liquid handling operating costs posed by pipette tips, and lessens timelines associated with pipette tip wash protocols. Laboratories employing single-use pipette tips incur huge costs considering that an automated discovery lab can use thousands of tips in a typical day. The consumable costs and duration of the assay continue to increase with each tip use and wash. To meet this demand, Cerionx has developed a tip cleaning technology platform to help streamline throughput, lower discovery costs and reduce contamination.

The TipCharger system generates an atmospheric plasma to clean and sterilize pipette tips used in automated liquid handling environments. The system specifically removes organic substances, can eliminate the need for time-consuming solvent-based wash stations and enables "disposable" polypropylene tips to perform like new after several hundred cleaning cycles. The technology increases efficiency by reducing the bottlenecks generally associated with automated liquid handling, produces high-quality results without contamination and reduces environmental waste.

Beyond the development of the TipCharger technology, it was vital to Cerionx's success that its product deliver significant results. To validate the TipCharger system, Cerionx employs a proven method from ARTEL, a company that specializes in liquid handling quality assurance. Using the MVS (Multichannel Verification System), Cerionx is able to measure--and prove--the consistent accuracy and precision of volume transfer steps after tips are exposed to plasma. The MVS is the only standardized, commercially available technology capable of accurate, precise and traceable measurement of delivered liquid volumes from automated liquid handlers.

"Given that drug discovery environments are heavily focused on shortening time-to-market for new therapeutics while simultaneously reducing operating costs," said Geoffrey Schwartz, Director of Applications, Cerionx, "working with quality standards like the MVS is essential for, not only TipCharger market acceptance, but also in helping Big Pharma meet this goal."

Trust development

In developing the TipCharger, Cerionx required a standard method for confirming pipetting precision and accuracy for tips cleaned. Traditional methods of performance testing, such as gravimetry or fluorescence, are difficult to administer accurately, and results are difficult to compare. For example, gravimetric calibration, where volume is verified by weighing liquid quantities on a balance, is time consuming and prone to environmental and manual error, especially at small volumes. In addition, gravimetry is not ideal for multichannel devices because of the extraordinary time required to measure each separate tip. Alternatively, gravimetry can be used to measure aggregate volumes that are dispensed from all tips simultaneously to provide an average assessment of all channels. This method artificially assumes that all tips behave identically, which is not always the case.

In fluorescence, the precision of a volume dispensed from a multichannel dispenser is easy to measure. Measuring the accuracy, however, is much more time consuming and usually requires a standard curve to be generated with a calibrated pipette from a skilled operator. Precision and accuracy are important terms to distinguish when referring to pipetting steps, as precision refers to the closeness of a group of volumes to each other regardless of a standard, while accuracy describes the deviation among a group of volumes from that of a standard volume. The ARTEL MVS is the only system that produces traceable accuracy and precision measurements in one simple procedure.

"The fact that the MVS measures both precision and accuracy is vital to the development and implementation of TipCharger," said Schwartz. "The dynamics of our industry demand that we deliver not just relevant quality but absolutely accurate and consistent data. The MVS helped us determine the quality threshold of TipCharger and provided documentation of those parameters as well."

MVS at work

The ARTEL MVS is based on proprietary ratiometric photometry, which employs a dual-dye, dual-wavelength absorbance methodology. This technology relies on two colorimetric dyes with distinct absorbance maxima at 520 nm (red) and 730 nm (blue).

The Beer-Lambert law states that when light passes through a solution containing some concentration of dye, the amount of light absorbed by the dye solution is proportional to both the concentration of dye and the pathlength of the light with the solution. If both the molar absorptivity and concentration of the dye solution are known and closely controlled, which is the case with the MVS, the law can be used to determine an unknown pathlength traversed by a photometric light beam. By measuring the pathlength through the solution and knowing the dye concentration, the unknown volume can be calculated through a series of equations. (1)

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The absorbance per unit pathlength of the red and blue dyes--NIST-traceable information determined during ARTEL's manufacturing process--is recorded on a barcode on each reagent bottle, further reducing measurement variability and uncertainty. Barcodes on the system's microtitre plates, sample solutions and calibrator plate contain performance information that is passed to the system's software through scanning. The MVS plate reader collects photometric measurements of the dye solutions dispensed into the microtitre wells by the automated liquid handler. These measurements, together with the barcode information, are used to rapidly determine both the precision and accuracy of the volume delivered from each tip of the device being tested.

"The MVS is effective for us because it is straightforward, standardized, and foolproof--everything from the barcoding to the fact that samples are stable and ready for use," said Schwartz. "It is a straightforward verification method for us internally as well as for our customers."

Comparing apples with apples

Cerionx wanted a method that illustrates the quality and performance of its TipCharger in standard terms across liquid handlers. And it also wanted those results to integrate with customers' own data. Many leading biotechnology companies use the ARTEL MVS to certify the volume transfer performance of their many liquid handling instrument types.

Schwartz also points out that, in addition to streamlining communication with customers, the MVS also provides peace of mind through third-party reputation: "This solution provides us with non-subjective data that builds credibility with our customers. Our plasma-based cleaning method is highly effective with solid data behind it--that's the combination our customers need to fully take advantage of their automated environments."

Effective results

The results of TipCharger implementation have been significant. From a financial perspective, the system saves companies the cost of replacing disposable tips after every use. Depending on the tip format and usage, eliminating the need for multiple boxes of tips on a daily basis can save laboratories from $50,000 to more than $800,000 annually on a single liquid handling platform.

"For most of our customers these kinds of operating expenses were thought of as simply the cost of doing business," said Schwartz. "Now those dollars can be better invested elsewhere."

However, the benefits of TipCharger go beyond the cost savings from reusing pipette tips. For laboratories that are cleaning and reusing tips with a solvent-based solution, time savings can be another clear benefit. For example, washing pipette tips can take up to several minutes while the plasma-based cleaning can take as little as two seconds.

In addition, plasma technology offers a more thorough method of cleaning tips. The system alters contaminants on an atomic level, removing them from the pipette tip as opposed to solvent-based methods, which simply dilute substances and are potentially less consistent and controlled. In addition, the plasma technology removes the need for aggressive cleaning compounds such as bleach that can be difficult to handle, and harmful to personnel. Immediate results in the lab can translate into a longer-term positive impact. Schwartz points out that, in analysis and discovery, even small deviations in results can delay projects, lead to false conclusions and increase the time to market:

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"It's critical that every stage is extremely accurate down to the nanolitre because those volumes directly correlate to the actual concentration of reagent in an assay. On a small scale, over-dispensing or under-dispensing can have a severe impact on achieving therapeutic efficacy," said Schwartz. "However, at a macro level, inaccuracy or imprecision can affect entire projects and the decision making of a project team. That is why it is vital that the TipCharger System performs consistently from the first cleaning cycle to the last."

Inaccuracies that are overlooked in the development lifecycle can severely affect the success or failure of any biotech product. In essence, an assumption of accuracy can set off a chain reaction of incorrect results that eventually cause a project to fail. And in many assays using high density plates, such as some cell-based assays, volume inaccuracies of less than one microlitre can significantly alter results.

As the biotech industries become more competitive, increasing demand for truncated development and more rapid times to market are facts of life. Technologies, such as TipCharger, offer a solution that both speeds the process and improves quality.

By using a complementary technology, such as the ARTEL MVS, to validate the performance of liquid handlers after using TipCharger, Cerionx is able to demonstrate the effectiveness of its product. Hence, automated laboratories benefit from a proven technology that can speed their cleaning processes, helping them better maintain the momentum of drug development, better allocate resources and compete more effectively.

References

(1.) Bradshaw, J. et al., Multichannel Verification System (MVS): A Dual-Dye Ratiometric Photometry System for Performance Verification of Multichannel Liquid Delivery Devices. J. Assoc. Lab. Autom., 2005, 10, 35-42.