TY - JOUR

T1 - Influence of nanoparticle encapsulation and encoding on the surface chemistry of polymer carrier beads

AU - Scholtz, Lena

AU - Tavernaro, Isabella

AU - Eckert, J. Gerrit

AU - Lutowski, Marc

AU - Geißler, Daniel

AU - Hertwig, Andreas

AU - Hidde, Gundula

AU - Bigall, Nadja C.

AU - Resch-Genger, Ute

N1 - Funding Information: This research was carried out in part at the electron microcopy center at BAM. The authors would like to thank Ines Feldmann from BAM division 4.2 for the SEM measurements, Carsten Prinz from BAM division 6.3 for the STEM measurements (TEM owned by HU Berlin—Prof. Nicola Pinna), Dr. A. Schaefer from the Institute for Chemistry and Biochemistry, Free University Berlin for providing the NMR facilities (supported by DFG) and Toufiq Elahi from BAM division 1.2/FU Berlin for excellent assistance in particle synthesis. Funding Information: Open Access funding enabled and organized by Projekt DEAL. L. S. acknowledges funding by the European Metrology Programme for Innovation and Research (EMPIR) as part of the project „AeroTox “ (18HLT02) and D. G. by project METVES II (18HLT01). The EMPIR initiative is co-funded by the European Union’s Horizon 2020 research and innovation programme and by the EMPIR participating states. I. T. acknowledges financial support from the WIPANO project AquaFunkNano (Federal Ministry for Economic Affairs and Climate Action (BmWK)) and the project MiGraGen (Novo Nordisk Fonden; Interdisciplinary Synergy Programme 2021). J. G. E. acknowledges funding by the MWK—School for Additive Manufacturing SAM. N.B. acknowledges funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy within the Cluster of Excellence PhoenixD (EXC 2122, Project ID 390833453).

PY - 2023/12

Y1 - 2023/12

N2 - Surface-functionalized polymer beads encoded with molecular luminophores and nanocrystalline emitters such as semiconductor nanocrystals, often referred to as quantum dots (QDs), or magnetic nanoparticles are broadly used in the life sciences as reporters and carrier beads. Many of these applications require a profound knowledge of the chemical nature and total number of their surface functional groups (FGs), that control bead charge, colloidal stability, hydrophobicity, and the interaction with the environment and biological systems. For bioanalytical applications, also the number of groups accessible for the subsequent functionalization with, e.g., biomolecules or targeting ligands is relevant. In this study, we explore the influence of QD encoding on the amount of carboxylic acid (COOH) surface FGs of 2 µm polystyrene microparticles (PSMPs). This is done for frequently employed oleic acid and oleylamine stabilized, luminescent core/shell CdSe QDs and two commonly used encoding procedures. This included QD addition during bead formation by a thermally induced polymerization reaction and a post synthetic swelling procedure. The accessible number of COOH groups on the surface of QD-encoded and pristine beads was quantified by two colorimetric assays, utilizing differently sized reporters and electrostatic and covalent interactions. The results were compared to the total number of FGs obtained by a conductometric titration and Fourier transform infrared spectroscopy (FTIR). In addition, a comparison of the impact of QD and dye encoding on the bead surface chemistry was performed. Our results demonstrate the influence of QD encoding and the QD-encoding strategy on the number of surface FG that is ascribed to an interaction of the QDs with the carboxylic acid groups on the bead surface. These findings are of considerable relevance for applications of nanoparticle-encoded beads and safe-by-design concepts for nanomaterials.

AB - Surface-functionalized polymer beads encoded with molecular luminophores and nanocrystalline emitters such as semiconductor nanocrystals, often referred to as quantum dots (QDs), or magnetic nanoparticles are broadly used in the life sciences as reporters and carrier beads. Many of these applications require a profound knowledge of the chemical nature and total number of their surface functional groups (FGs), that control bead charge, colloidal stability, hydrophobicity, and the interaction with the environment and biological systems. For bioanalytical applications, also the number of groups accessible for the subsequent functionalization with, e.g., biomolecules or targeting ligands is relevant. In this study, we explore the influence of QD encoding on the amount of carboxylic acid (COOH) surface FGs of 2 µm polystyrene microparticles (PSMPs). This is done for frequently employed oleic acid and oleylamine stabilized, luminescent core/shell CdSe QDs and two commonly used encoding procedures. This included QD addition during bead formation by a thermally induced polymerization reaction and a post synthetic swelling procedure. The accessible number of COOH groups on the surface of QD-encoded and pristine beads was quantified by two colorimetric assays, utilizing differently sized reporters and electrostatic and covalent interactions. The results were compared to the total number of FGs obtained by a conductometric titration and Fourier transform infrared spectroscopy (FTIR). In addition, a comparison of the impact of QD and dye encoding on the bead surface chemistry was performed. Our results demonstrate the influence of QD encoding and the QD-encoding strategy on the number of surface FG that is ascribed to an interaction of the QDs with the carboxylic acid groups on the bead surface. These findings are of considerable relevance for applications of nanoparticle-encoded beads and safe-by-design concepts for nanomaterials.

UR - http://www.scopus.com/inward/record.url?scp=85165584800&partnerID=8YFLogxK

U2 - 10.1038/s41598-023-38518-7

DO - 10.1038/s41598-023-38518-7

M3 - Article

C2 - 37488159

AN - SCOPUS:85165584800

VL - 13

JO - Scientific reports

JF - Scientific reports

SN - 2045-2322

IS - 1

M1 - 11957

ER -