Eckert, Kathrin MarinaKathrin MarinaEckertDittmer, Kayla ReataKayla ReataDittmerSetiawan, SherlianaSherlianaSetiawanOhde, DanielDanielOhdeLiese, AndreasAndreasLieseSmirnova, IrinaIrinaSmirnova2026-06-292026-06-292026-06-25Industrial & Engineering Chemistry Research (in Press): (2026)https://hdl.handle.net/11420/63659Stimuli-responsive gels, known as smart materials, undergo reversible changes through solvent uptake or expulsion. Building on prior material characterization (Paper A), this study evaluates their performance in a plug-flow reactor under changing temperature (25–40 °C) and pH (8–4) conditions using formate dehydrogenase for NADH regeneration from NAD+. Temperature changes caused transient increases in activity at elevated temperatures, followed by partial or pronounced loss after returning to mild conditions, indicating limited effects of gel responsiveness. In contrast, under pH changes, activity decreased under acidic conditions but fully recovered for responsive hydrogels, maintaining high residual activity (93.3 ± 26.3% for pH-responsive and 91.0 ± 9.8% for dual-responsive carriers), whereas non-responsive silica carriers showed irreversible loss, retaining only 27.6 ± 10.2% of the initial yield. This behavior is attributed to gel shrinkage, which restricts mass transport and reduces enzyme exposure to the surrounding environment. These results demonstrate the potential of responsive hydrogels as adaptive enzyme carriers for biocatalysis.en1520-50452026American Chemical Society (ACS)https://creativecommons.org/licenses/by/4.0/Technology::660: Chemistry; Chemical Engineering::660.6: BiotechnologyNatural Sciences and Mathematics::572: BiochemistryJournal Articlehttps://doi.org/10.15480/882.1737110.1021/acs.iecr.6c0096010.15480/882.17371