Choosing the Right Plate Reader or Bioluminescence Imager: A Conversation with Joshua Sopp

Joshua Sopp
​Product Specialist, Promega UK
​joshua.sopp@promega.com

What is your background, and what led you to specialise in detection instruments?

I did my PhD in experimental cancer biology at the University of Southampton, then moved into industry at Novacyt and RevoNA Bio, developing diagnostic and high-throughput screening assays for RNA-selective compounds, before joining Promega.

Looking back, the common thread wasn't the disease area, it was the instrumentation. Whether I was working with qPCR platforms, SPR, or plate readers, I kept finding myself drawn to the tools themselves. How they worked, where they fell short, and what made the difference between an assay that ran smoothly and one that constantly needed troubleshooting. That's what led me here, now managing the HiBiT protein tagging portfolio alongside our plate readers and luminescence imaging systems.

When a researcher comes to you looking for a plate reader, what do you typically ask them first?

What are you actually measuring? Luminescence, fluorescence, absorbance, BRET, FRET, or some combination, the detection mode determines whether a dedicated luminometer like the GloMax^® Navigator or a multimode reader like the Discover or Explorer fits best. It also depends on the material: a lab quantifying DNA or RNA ahead of NGS library prep needs accurate fluorescence detection, not luminescence at all.

That's different again from labs running cell viability assays with CellTiter-Glo^®, measuring analytes with Lumit™ Immunoassays, or NanoLuc^® and NanoBiT^® studies, which need the sensitivity and dynamic range to resolve both faint and strong protein signals without saturating the detector. I also ask about throughput: 96-well, 384-well, or both, and whether high-throughput screening is part of the workflow.

Can you explain the difference between the GloMax^® plate reader range and the GloMax^® Galaxy bioluminescent imager platform?

They answer different questions that complement each other. The GloMax^® Discover, Explorer and Navigator are optimised specifically for luminescence, absorbance, fluorescence and BRET. The GloMax^® range integrates directly with Promega's assay portfolio, which means the protocols, validation data and technical support are all aligned. The Discover and Explorer, in particular, suit high-throughput work, supporting 6- to 384-well formats.

The Galaxy Bioluminescence Imager goes a step further, built around NanoLuc^® luciferase technology, sensitive enough to capture signal from endogenous protein levels in a benchtop set-up, no more blacking out a room. It lets you see what's actually happening in your cells rather than relying on a well average, for example, confirming whether a degrader affects a whole population evenly or only certain cells. Being able to see how single cells respond to a treatment, in real time, answers a lot of questions, and opens up plenty more.

Both are capable instruments. The right choice depends on the lab's day-to-day work and how much assay-specific support they want alongside the hardware.

What are the most common misconceptions you encounter when researchers are choosing a bioluminescence or detection platform?

There are two big ones I run into a lot. First, people assume bioluminescence is less sensitive than fluorescence. It's actually the reverse. Because there's no autofluorescence or inherent background light from the cells themselves, bioluminescence gives you a much larger signal-to-background ratio, which is why it's so well suited to detecting genuinely low-abundance targets, endogenous protein levels, for example, rather than overexpressed constructs.

Second, people assume plate readers can't handle live-cell kinetic assays, that imaging is the only option for watching a process unfold. Not true. Bioluminescence isn't phototoxic and doesn't photobleach, so cells can be tracked continuously using kinetic read programs on instruments like the GloMax^® range. Imaging becomes the next step only when you want single-cell, spatial detail rather than a well average.

Where I do think it's worth setting expectations honestly: bioluminescence imaging isn't quite as fast, frame for frame, as fluorescence imaging. Since it's capturing self-emitted light rather than an excited fluorophore, the camera needs longer integration times to collect enough photons for a usable image. It's not a limitation so much as a trade-off, you're gaining a huge sensitivity and background advantage in exchange for slightly longer acquisition times.

What role does software and data analysis play in instrument selection?

It's underrated. Researchers spend a lot of time thinking about sensitivity, dynamic range, and detection modes, which are all important, but the software experience is what they live with every day. The GloMax^® instruments come with integrated software guiding plate setup, acquisition and result calculation. A drag-and-drop protocol builder means researchers can set up a new assay without wrestling with complicated menus, and for Promega's own assay chemistries, like CellTiter-Glo^® and RealTime-Glo^®, the software comes with pre-built, validated protocols that are genuinely plug-and-play. Built-in analysis then takes you straight from raw signal to a usable result. That guided experience cuts variability and training time for newer users, while experienced users can still customise. Easy to overlook on a spec sheet, but it matters daily.

Are there particular research applications where the GloMax^® or Galaxy instruments really stand out?
The GloMax^® platform is engineered specifically around NanoLuc^® luciferase chemistry, which means very high sensitivity and low cross-talk between wells, exactly what you need when you're trying to resolve small differences in signal rather than just detecting ‘on or off.’

That combination of sensitivity and dynamic range shows up across a few applications I see constantly. Cell proliferation studies, using products like CellTiter-Glo^®, rely on detecting genuinely low signal changes reliably, and that's where dynamic range matters as much as raw sensitivity. In drug discovery, Lumit^® immunoassays let researchers measure cytokines directly in cell culture media without a wash step, which is a very different workflow demand to a standard endpoint assay. And for anyone working on protein detection or protein-protein interactions, HiBiT and NanoBiT^® technologies are built to work with exactly this kind of sensitive, low-background luminescence detection, whether that's confirming endogenous protein expression or resolving a genuine interaction from background noise.

The Galaxy Bioluminescence Imager tends to come into its own on top of that, specifically where researchers need to see rather than just measure. GPCR research is a strong fit, watching receptor internalisation or β-arrestin recruitment in real time, at the single-cell level, gives you a much richer picture than a single well-average number ever could.

What have you found most rewarding about this role so far?

It's the variety, more than anything. One week it's troubleshooting a cytotoxicity assay, the next it's a lab that's found a completely new use for the Galaxy imager I hadn't considered. That's one of my favourite parts of the job, customers pushing the instruments into applications I wouldn't have predicted, and then getting to see the data that comes back from it. I also enjoy the problem-solving: working through a tricky question with a customer until we land on something that actually fits their science, then sharing what I've learned more widely so it helps beyond just that one conversation.

What do you enjoy outside of work?

Cycling, mostly. There's something about heading out into the New Forest and genuinely losing track of where I am for a couple of hours that clears my head. Closer to home, it's long walks with my family and our cockapoo, who has strong opinions about which routes are acceptable. And travelling, though it's changed a bit. It used to mean proper adventure and getting off the beaten track. These days, with young kids, it's more likely to revolve around a waterpark and ice cream!

Want to Find Out More?

Explore the GloMax^® and Galaxy instrument pages on the Promega UK website, or get in touch with Joshua or your local Promega representative.  

GloMax^® Plate Readers

GloMax^® Galaxy Bioluminescent Imager