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This study explores the use of multiphoton microscopy to enhance colorectal cancer detection, by using two-photon excitation fluorescence of intrinsic fluorophores. The diagnostic capability of this technique hinges on two key metabolic enzymes, nicotinamide adenine dinucleotide and flavin adenine dinucleotide, which serve as intrinsic biomarkers of cellular metabolism. This study focuses on integrating two-photon excitation fluorescence (TPEF) into conventional colonoscopes by miniaturizing the optical setup and incorporating highly selective optical filters for nicotinamide adenine dinucleotide and flavin adenine dinucleotide fluorescence detection. While the current work does not demonstrate a fully miniaturized implementation, the presented filters are explicitly designed for future miniaturization. Their thin-film dielectric structure allows seamless integration into compact platforms, such as fiber-optic probes or on-chip photodetectors, supporting the long-term objective of embedding TPEF into clinical colonoscopy systems. This paper introduces specially designed optical filters optimized for detecting nicotinamide adenine dinucleotide (at 485 nm) and flavin adenine dinucleotide (at 535 nm) fluorescence signals. Our results demonstrate that these filters effectively distinguish fluorescence signals from nicotinamide adenine dinucleotide and flavin adenine dinucleotide, enabling accurate differentiation between normal and cancerous tissue phantoms. The redox ratio analysis demonstrated a clear difference between tumoral (0.9680\u2009\u00b1\u20090.0307) and normal (0.6014\u2009\u00b1\u20090.0035) phantoms, highlighting the potential of the developed filters for colorectal cancer detection. This advancement lays a strong foundation for non-invasive cancer diagnostics, potentially enhancing early detection and improving patient outcomes.<\/jats:p>","DOI":"10.1007\/s11082-025-08309-7","type":"journal-article","created":{"date-parts":[[2025,6,20]],"date-time":"2025-06-20T12:00:02Z","timestamp":1750420802000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["NAD(P)H\u2013FAD fluorescence detection using multiphoton microscopy improved with highly selective optical filters"],"prefix":"10.1007","volume":"57","author":[{"given":"Ruben B.","family":"Freitas","sequence":"first","affiliation":[]},{"given":"Manuel J. L. 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