Single-pass tangential flow filtration (SPTFF) concentrates a macromolecule solution by passing it once through one or more membrane stages, rather than recirculating it in a batch loop. It matters for patent purposes because the most-cited filing in this dataset, WO2019236811A1 and its US counterpart, claims a specific hybrid configuration where membranes of different molecular weight cutoffs are staged in series within a single pass. That specific staging is the element competitors need to design around, not the general concept of single-pass filtration.

This dataset's assignee ranking covers four companies and all 14 records in scope — the leader holds 9 records, with the remaining three splitting the rest. Because the ranked list is short, describing it as a 'top 50' or similar would be misleading; it is the complete set the data endpoint returns for this search. Recent-year filing activity is thin across all four, with only one record attributed to any assignee in the latest year.

The clearest gap is C12N (microorganisms and genetic engineering), which appears in only 1 of the 14 records against 13 for C07K and 6 for B01D. That points to under-claimed territory around tying UF/DF process parameters directly to upstream cell-culture or expression-system characteristics, rather than treating concentration as a purely downstream physical step. Filing activity in India, Canada and Australia is also limited to a single record each, which is comparatively open ground relative to the WIPO/PCT and EPO filings.

No — high filing density in a narrow branch, such as C07K at 92.9% of the 14 records, means that particular claim space is occupied, not that the underlying technology has stopped evolving. It signals where existing claims are dense and where a new filer faces more prior art to clear. Growth rate is not computable for this dataset because there are fewer than four complete filing years once the roughly 18-month publication lag is accounted for, so filing counts alone should not be read as a maturity signal either.

US20210253633A1, assigned to Bristol-Myers Squibb Company and published 2021-08-19, claims a method of concentrating a macromolecule solution using a hybrid configuration of at least two semi-permeable membranes with different molecular weight cutoffs staged in series in a single-pass tangential flow filtration apparatus. It blocks that specific staged, differing-cutoff, single-pass combination, applicable to proteins, antibodies and nucleic acids. It does not block conventional single-membrane UF/DF or multi-pass staged systems, since those fall outside the single-pass and differing-cutoff limitations of the claim.