Diagnostic nanoparticle targeting of the EGF-receptor in complex biological conditions using single-domain antibodies Zarschler, Kristof Prapainop, Kanlaya Mahon, Eugene Rocks, Louise Bramini, Mattia Kelly, Philip M. Stephan, Holger Dawson, Kenneth A. Nanoparticles EGF-receptor Antibodies We thank Utta Herzog for excellent technical assistance. Financial support by the Helmholtz Virtual Institute NanoTracking (Agreement Number VH-VI-421) is gratefully acknowledged. This study is part of a research initiative “Technologie und Medizin – Multimodale Bildgebung zur Aufklärung des in vivo Verhaltens von polymeren Biomaterialien” of the Helmholtz-Portfoliothema. Financial support through Science Foundation Ireland and the Irish Research Council (IRC) are gratefully acknowledged. The work performed was supported by the IRC through an Enterprise Partnership Postdoctoral Fellowship with Intel (Ireland) (Ref no: EPSPD/2012/443) and the IRCSET EMPOWER Postdoctoral Fellowship Scheme. Experimental method development supported through the QualityNano research infrastructure is acknowledged. For effective localization of functionalized nanoparticles at diseased tissues such as solid tumours or metastases through biorecognition, appropriate targeting vectors directed against selected tumour biomarkers are a key prerequisite. The diversity of such vector molecules ranges from proteins, including antibodies and fragments thereof, through aptamers and glycans to short peptides and small molecules. Here, we analyse the specific nanoparticle targeting capabilities of two previously suggested peptides (D4 and GE11) and a small camelid single-domain antibody (sdAb), representing potential recognition agents for the epidermal growth factor receptor (EGFR). We investigate specificity by way of receptor RNA silencing techniques and look at increasing complexity in vitro by introducing increasing concentrations of human or bovine serum. Peptides D4 and GE11 proved problematic to employ and conjugation resulted in non-receptor specific uptake into cells. Our results show that sdAb-functionalized particles can effectively target the EGFR, even in more complex bovine and human serum conditions where targeting specificity is largely conserved for increasing serum concentration. In human serum however, an inhibition of overall nanoparticle uptake is observed with increasing protein concentration. For highly affine targeting ligands such as sdAbs, targeting a receptor such as EGFR with low serum competitor abundance, receptor recognition function can still be partially realised in complex conditions. Here, we stress the value of evaluating the targeting efficiency of nanoparticle constructs in realistic biological milieu, prior to more extensive in vivo studies. 2026-02-17T10:26:31Z 2026-02-17T10:26:31Z 2014-04-16 journal article Zarschler, Kristof et al. Diagnostic nanoparticle targeting of the EGF-receptor in complex biological conditions using single-domain antibodies. Nanoscale, 2014, 6, 6046. DOI: 10.1039/c4nr00595c https://hdl.handle.net/10481/111081 10.1039/C4NR00595C eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Royal Society of Chemistry