Catalytic single-chain polymeric nanoparticles at work: from ensemble towards single-particle kinetics

Abstract

a Folding a single polymer chain around catalytically active sites to construct catalytic single chain polymeric nanoparticles (SCPNs) is a novel approach to mimic the activity and selectivity of enzymes. In order to relate the efficiency of SCPNs to their three-dimensional structure, a better understanding of their catalytic activity at an individual level, rather than at an ensemble level, is highly desirable. In this work, we present the design and preparation of catalytic SCPNs and a family of fluorogenic substrates, their characterization at the ensemble level as well as our progress towards analyzing individual SCPNs with single-molecule fluorescence microscopy (SMFM). Firstly, organocopper-based SCPNs together with rhodamine-based fluorogenic substrates were designed and synthesized. The SCPNs catalyze the carbamate cleavage reaction of mono-protected rhodamines, with the dimethylpropargyloxycarbonyl protecting group being cleaved most efficiently. A systematic study focusing on the conditions during catalysis revealed that the ligand acceleration effect as well as the accumulation of substrates and catalytically active sites in SCPNs significantly promote their catalytic performance. Secondly, a streptavidin-biotin based strategy was developed to immobilize the catalytic SCPNs on the surface of glass coverslips. Fluorescence correlation spectroscopy experiments confirmed that the SCPNs remained catalytically active after surface immobilization. Finally, single-SCPN activity measurements were performed. The results qualitatively indicated that fluorescent product molecules were formed as a result of the catalytic reaction and that individual fluorescent product molecules could be detected. So far, no evidence for strongly different behaviors has been observed when comparing individual SCPNs.

Macromolecular Superstructures: A Future Beyond Single Chain Nanoparticles

“…Further, the helicity of these internal domains can be tuned based on the chirality of the alkyl side chains of the BTA units . These complex internal domains have further been used to design a broad array of SCNPs, which are catalytically active in water …”

“…[57] These complex internal domains have further been used to design a broad array of SCNPs, which are catalytically active in water. [58][59][60][61]…”

“… A) Schematic representation of the photoinduced folding of porphyrin‐cored star polymers (PCSP) into a porphyrin‐cored polymer nanoparticle (PCPN) upon anthracene dimerization. B) Chemical structure of the parent PCSP . Adapted with permission from Inorg.…”

Tuning Reactivity of Micellar Nanoreactors by Precise Adjustments of the Amphiphiles and Substrates Hydrophobicity

“…10 Micelles can provide solubility and protective environment for the lipophilic reactants, shielding them from the surrounding aqueous environment. 11,12 In recent years, significant progress in conducting organic transformation and specifically organometallic reactions has been reported by Lipshutz, [12][13][14][15][16][17] Meijer, 3,18,19 Unciti-Broceta 5,[20][21][22][23][24] Zimmerman, [25][26][27] and others. [28][29][30][31][32] The ability to perform organometallic reactions in aqueous media can contribute significantly to increasing the sustainability of organic synthesis by reducing the usage of organic solvents.…”

Wavelength‐Selective Folding of Single Polymer Chains with Different Colors of Visible Light

“…Such an orthogonality was achieved using non-covalent recognition sites, as utilized in the pioneering work of Meijer and Palmans, [24,25] to stepwise fold [26] or unfold [27] single polymer chains. However, a major motivation for research in the field of SCNPs results from their application as catalytic nanoreactors, [25,[28][29][30] inspired by the unmatched catalysis of enzymes. By replacing the non-covalently driven folding with covalent bond formations, the final polymeric architectures of the Sparing the usually required addition of reagents or catalysts, [31,32] we report the first additive-free stepwise folding of single polymer chains based on covalent bond formations.…”