Article

The design of reagents sets the pace for point-of-care diagnostics

Start one-step ahead: glycerol-free reagents in high concentration designed for use in dried-down assays

The concept of point-of-care diagnostics – the rapid and sensitive detection of analytes at or near the patient – has been around for decades. Recent public health experiences, however, have propelled the urgency to develop and deploy point-of-care (PoC) tests into the limelight. Undoubtedly, molecular diagnostics plays an increasingly pivotal role in global health and, as the SARS-CoV-2 pandemic clearly revealed, is a first line of defense in understanding and managing future emergencies. The question is no longer ‘do we need to test onsite?’ but

‘how can we test around the world, regardless of location, climate, facilities, and testers?’

PoC: standardized results under variable conditions

Developing and manufacturing a diagnostic assay worthy of regulatory approval is a complex endeavor. Yet, a lot can be done to standardize assay performance and ensure reliable outcomes by minimizing external confounding variables. Samples tested can be normalized through analyte extraction or matrix depletion. Shelf life can be maintained through tightly controlled storage conditions. Sample and assay handling can be standardized through training. None of these strategies, however, are realistic in a PoC setting. When a diagnostic assay destined for PoC leaves the warehouse, the manufacturer no longer controls factors that impact its life cycle and performance. The manufacturer is challenged to deliver reliable, standardized results in a highly variable context. And to do so quickly and cost-effectively.

So, what options does a manufacturer have?

Create a reliable assay through variation-tolerant reagents and simple architecture.

Well-designed reagents are the key to PoC

Raw materials have never been trivial for the development of an assay. For PoC diagnostics though, the choice of materials becomes critical.
Reagents must not only deliver quality, but also withstand variation in transport, sample, user, and testing conditions.

A reagent designed for PoC:

is formulated for direct dry down in master mixes, saving production steps and accelerating development time
is highly concentrated to save sample space and boost sensitivity
performs robustly under suboptimal handling and with suboptimal samples
delivers the sensitivity, speed, and multiplexing capacity that shortens turnaround times

These criteria define the Roche CustomBiotech lyophilization-ready (lyo-ready) reagents, a unique portfolio of high-performance enzymes that streamline the development and production of diagnostic assays intended for PoC.

Glycerol-free: for lower complexity and cost-saving

Lyophilizing reagent mixes eases transport and storage of a diagnostic test. Reduced weight, smaller size, and stability at room temperature are some of the advantages. However, drying down reagents stabilized with over 0.5% glycerol complicates production because they must first be dialyzed to remove the glycerol, rebuffered, and tested.

Roche CustomBiotech offers glycerol-free enzyme formulations that can be lyophilized directly, saving production steps, time, and costs. Hence, lyo-ready reagents enable streamlining which leads to:

Reduction of enzyme losses up to 20% during glycerol removal
No need for additional testing
Lower labor costs

Furthermore, these high-quality enzymes show stable performance after long-term storage at room temperature (Figure 1).

Figure 1. Lyophilized glycerol-free KAPA3G HotStart DNA polymerase retains enzymatic activiy even at high storage temperatures.
Stored at 37°C for over 4 months, the lyohilized format delivers the same high performance as non-lyophilized enzyme stored at -20°C.

High concentration: for more sample space

The lyo-ready concept entails not only a glycerol-free formulation but also high concentration. When highly concentrated, lyo-ready reagents containing glycerol can be added to a mix in small amounts, so glycerol remains below the threshold of 0.5% for dry down. An extra advantage of high-concentration reagents is that they free up more room in a reaction for larger sample volumes, which then boosts assay sensitivity.

Our commitment to setting the pace for PoC diagnostics does not stop at enzymes and master mixes. Roche CustomBiotech delivers a broad spectrum of premium ingredients at scale and on time for assays used today and those to come tomorrow.