Binding of fluorescent reporters to the surface of aldehyde-functionalized microparticles

Schematic representation of the binding of fluorescent reporters to the surface of aldehyde-functionalized microparticles

Source: BAM, Division Biophotonic

The surface functionalization of 2D-supports or micro- and nanoparticles with different chemical groups plays an important role for many applications of these materials in the life sciences. Especially aldehyde-functionalized materials have found widespread applications, such as the coupling of aldehyde surface groups with proteins, peptides, or amine-functionalized oligonucleotides to readily produce biomolecule-decorated biochip and bead surfaces for the simultaneous analysis of different analytes. Moreover, aldehydes can serve as anchor sites for the attachment of biomolecules or as reversible binding sites for proteins on cell surfaces. However, the use of aldehyde-based materials in bioanalytical and medical settings require reliable and accurate methods to detect and quantify this functionality.

Our group developed a versatile concept to quantify the number of accessible aldehyde moieties on particle surfaces through the specific binding and subsequent release of small reporter molecules such as fluorescent dyes and nonfluorescent chromophores. Unlike other methods, this new strategy separates the signal-generating molecules from the bead surface prior to analysis, thereby circumventing common issues associated with light scattering and signal distortions caused by binding-induced changes in the optical properties of the reporter, as well as quenching dye–dye interactions on crowded particle surfaces. Our newly developed strategies enable a reliable and sensitive quantitative comparison of bead batches with different aldehyde functionalization densities, and a qualitative prediction of their coupling efficiencies in bioconjugation reactions.

Quantification of Aldehydes on Polymeric Microbead Surfaces via Catch and Release of Reporter Chromophores
Alexander Roloff, Nithiya Nirmalananthan-Budau, Bastian Rühle, Heike Borcherding, Thomas Thiele, Uwe Schedler, Ute Resch-Genger
published in Analytical Chemistry, Vol. 91, Issue 14, Pages 8827-8834
BAM, Division Biophotonics