Precise functionalization of NPs towards chiral NP dimers

In the ChiroSense project we are developing a new chiroptical biosensor based on a dimer of gold and silicon nanoparticles (NPs), utilizing plasmonically enhanced circular dichroism (CD) measurements to probe molecule conformation in solution with increased sensitivity [1]. The development will strongly be guided by the use of consensus tetratricopeptide repeat (CTPR) proteins as a highly modular and well-defined structural probe, while simultaneously being employed as structural linker of the nano-particle dimer [2]. To deconvolute the structural and molecular components of the CD signal, the dimer will also be formed using single stranded DNA (ssDNA), which is also modular but lacks the distinct CD signal of CTPR [3]. Precisely controlling the loading ratio of molecules per NP is crucial for both approaches to achieve stable NPs that do not aggregate but are still able to form dimers.

Here we present our initial results on the development of these chiral NP dimers. To achieve functionalized NPs that enable dimer formation, it is important to achieve low loading ratios, to avoid aggregation, while maintaining the NP stability in solution. We developed a PEG based approach that allows us to precisely control the NP loading ratio, ranging from a few to several hundred molecules per NP. These particles were then used to synthesize chiral NP dimers with high yields.