Cavidi Secures US Patent Allowance for BOLD Signal-Amplification Technology

On 8 October 2026, the United States Patent and Trademark Office (USPTO) issued a Notice of Allowance for Cavidi's core patent application covering Enzyme Enhanced ELISA, the technology behind BOLD (Binding Oligo Ladder Detection) and Exazym®. Cavidi expects the US patent to issue later this autumn, once the remaining formalities are complete.

"This is an important step for Cavidi and for the partners developing applications around our technology. The US is a key market for the laboratories and assay developers we want to reach. Just as importantly, this milestone recognises years of scientific work and persistence by our team in Uppsala, and I'm proud of what we've accomplished," says Jonathan Royce, CEO of Cavidi.

More sensitive detection, without replacing laboratory equipment

ELISA is one of the most widely used methods in biomarker analysis, but detecting very low concentrations of biomarkers can be challenging. Improving sensitivity often means investing in new equipment.

BOLD amplifies the signal from a conventional ELISA, helping laboratories measure low-abundance targets. After antibodies capture their target, BOLD introduces an oligonucleotide-linked detection step, followed by signal amplification using reverse transcriptase. The antibodies retain their role in determining what the assay recognises, while BOLD strengthens the resulting signal. This builds on Cavidi's expertise in reverse-transcriptase technology, developed since the company was founded in 1984.

Built on BOLD, Exazym® is a reagent-based add-on designed to integrate into established laboratory workflows. Laboratories can continue using their existing plates and readers, as well as antibody pairs where validated, without needing a dedicated detection instrument. Assay-specific optimisation may be required, and Cavidi provides application support.

Results from more than 30 biomarkers tested to date show a 10–100× lower limit of detection, with performance depending on the assay, biomarker and sample. In a peer-reviewed study published in SLAS Technology in 2026, the team reported an approximately 67-fold improvement in the limit of detection for SARS-CoV-2 spike protein, in a matched comparison of the same antibodies with and without BOLD under the conditions tested.

From Uppsala to the USPTO

Cavidi filed its first patent application in Sweden in May 2021 and an international application in May 2022. The USPTO published the US application in June 2024, and the European Patent Office granted a European patent in May 2025.

Cavidi founder and board member Clas Källander led the development alongside Ingela Fridborg, the late Ingvar Pettersson and the scientific team in Uppsala. Colleagues remember Ingvar with deep gratitude for his contribution to the work.

Today, Peter Stenlund, Veronika Nordal and their colleagues continue to develop the technology and explore its applications. Nordal is first author and Stenlund corresponding author of the 2026 SLAS Technology study.

Learn more about Exazym® here: https://cavidi.se/exazym/