VITO NV | Boeretang 200 | BE-2400 Mol | + 32 14 33 55 11 | www.vito.be SUSTAINABLE - ENTREPRENEURIAL - INSPIRING - CREATIVE THE NATURE OF THE POLYMERIC GLYCO-LINKER CONTROLS THE SIGNAL OUTPUTS FOR PLASMONIC GOLD NANORODS BIOSENSORS IN COMPLEX MEDIA DUE TO BIOCORONA FORMATION Alessia Pancaro,a-b Michal Szymonik,a Panagiotis G. Georgiou,c Alexander N. Baker,c Marc Walker,e Peter Adriaensens,f Jelle Hendrix,b Matthew I. Gibsonc,d and Inge Nelissena a Health Unit, Flemish Institute for Technological Research (VITO), Mol, Belgium; b Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium; c Department of Chemistry, University of Warwick, Coventry, UK; d Warwick Medical School, University of Warwick, Coventry, UK; e Department of Physics, University of Warwick, Coventry, UK; fApplied and Analytical Chemistry, Institute for Materials Research, Hasselt University, Diepenbeek, Belgium. Aim: Evaluate the nature of RAFT polymer ligands on plasmonic lectin sensing in human serum. https://doi.org/10.1039/D1NR01548F BACKGROUND Poly(N-(2-hydroxypropyl) methacrylamide) (PHPMA) and poly(N- hydroxyethyl acrylamide) (PHEA) were synthesised by photo-initiated RAFT polymerization with different degrees of polymerisation (DP = 40, 50, 55, 68 for PHPMA and DP = 26, 35, 50, 60 for PHEA) by tuning the feed ratio. Conjugation of glycopolymers onto gold nanorods (A) UV-Vis (C) XPS (B) DLS (D) TEM High colloidal stability. Successful attachment of the glycopolymers to the gold particle surface. Higher surface grafting density for the PHEA polymer. This work is supported by: Marie-Curie European Training Network (MC-ETN) NanoCarb N° 814236; VITO; Hasselt University; the Research Foundation Flanders (FWO Vlaanderen; Hercules project AUHL/15/2 - GOH3816N); the ERC (Grant 866056); the BBSRC-funded MIBTP program (BB/M01116X/1) and Iceni Diagnostics ltd. The Warwick Polymer Research Technology Platform is acknowledged for SEC analysis, and the Warwick Electron Microscopy Research Technology Platform is acknowledged for TEM. ACKNOWLEDGEMENTS Lectin binding studies in buffer and human serum Contribution and impact of serum proteins on sensing performance • The chemistry of the polymer linker used for nanoparticle-based nanoplasmonic assays can impact the nature of the sensor response. • Initial screening of sensor response in buffer is not a reliable strategy for identification of the best-performing surface modifications for biosensing in complex biofluids. • The nature of polymeric tethers and their grafting density directs the formation of biocoronas in serum, and this has a huge impact on biosensing of lectins. CONCLUSIONS LSPR peak following the addition of glyco-GNRs to a dilution series of SBA in serum: A) Gal-PHPMA GNRs showed no response to SBA in the concentration range tested (in contrast to the strong LSPR shift observed in buffer alone). B) Gal-PHEA nanorods showed dose- dependent LSPR shifts plus SBA (in contrast to the aggregative behaviour observed for the same assay performed in buffer). Evolution of LSPR peak wavelength location over time (5 hours) after addition of Gal-PHEA35 GNRs to serum containing different SBA concentrations. The LSPR peak wavelength of Gal-PHEA GNRs in serum decreases upon SBA addition, consistent with overall loss of mass from the particle surface, rather than a net mass gain due to lectin binding. The localised surface plasmon resonance (LSPR) peak of gold nanorods (GNRs) is located in the near-infrared optical window and is sensitive to local binding events, enabling label-free detection of biomarkers in complex biological fluids. Glycan-binding proteins, called lectins, play a key role in many biological processes. To enable LSPR-based biosensing, the nanoparticles must be decorated with recognition units tethered to the surface by a ligand. We studied the sensing performance of GNRs coated with galactosamine-modified polymeric linkers fo