{
  "abstract": "Post-SELEX incorporation of environmentally responsive fluorescent nucleobase surrogates provides a powerful strategy for converting DNA aptamers into protein aptasensors, yet achieving large protein-induced fluorescence enhancement (PIFE) while preserving target affinity remains a major challenge.Here, we introduce a photobasic 4-(1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline (AnIm) nucleobase surrogate that enables ultraresponsive PIFE through site-specific incorporation into DNA aptamers.As a model system, AnIm was incorporated into two thrombin-binding aptamers that recognize distinct protein exosites: the 15-mer TBA15 and the 27-mer HD22.The modified aptamers retained high thrombin affinity (Kd = 85-167 nM).Within HD22, site-dependent fluorescence enhancements of 70-108-fold (Irel) were observed, affording a limit of detection (LOD) of 280 pM in PBS and 3.8 nM in 5% human serum.To our knowledge, this >100-fold fluorescence turn-on represents the largest PIFE response reported for a fluorescent nucleobase surrogate.Spectroscopic studies reveal that the exceptional sensitivity arises from a protein-induced pKa shift coupled with suppression of a twisted intramolecular charge-transfer (TICT) state.Protein binding shifts AnIm from its protonated (NH⁺) ground-state toward the neutral (N) form, reducing background fluorescence, while excited-state protonation generates a fluorescent molecular rotor whose emission is enhanced within the rigid protein microenvironment.These findings establish photobasic nucleobase surrogates as a general strategy for post-SELEX fluorescent aptamer engineering for ultra-responsive PIFE-based biosensing.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry and Toxicology",
    "University of Guelph",
    "Department of Chemistry and Biochemistry",
    "University of Lethbridge"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Matteo Pavlovic"
    },
    {
      "affs": [
        2,
        3
      ],
      "name": "Austin Pounder",
      "orcid": "0000-0002-5843-0922"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Naomi Varnovitski"
    },
    {
      "affs": [
        2,
        3
      ],
      "name": "Stacey D. Wetmore",
      "orcid": "0000-0002-5801-3942"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Richard A. Manderville",
      "orcid": "0000-0003-4035-8093"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2g2z8e752mkhe.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15008836/v1",
  "fulltext_url": null,
  "id": "2g2z8e752mkhe",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008836/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1312|Advanced biosensing and bioanalysis techniques"
    ]
  ],
  "openalex": "W7213303079",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15008836/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-15",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/2g2z8e752mkhe.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:19Z",
      "native_id": "10.26434/chemrxiv.15008836",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008836/v1"
    }
  ],
  "subjects": [
    {
      "field": "biochemistry",
      "origin": "openalex:1312|Advanced biosensing and bioanalysis techniques",
      "subfield": "molecular-biology"
    }
  ],
  "title": "Benzimidazole Modification of DNA Aptamers for Ultra Responsive Protein-Induced Fluorescence Enhancement",
  "title_text": "Benzimidazole Modification of DNA Aptamers for Ultra Responsive Protein-Induced Fluorescence Enhancement",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:19Z",
  "url": "https://research.draconitic.com/paper/2g2z8e752mkhe",
  "venue": "ChemRxiv",
  "versions": []
}