Complex aggregation of TPPS and PEG-b-P4VP in confined space

Abstract

To explore the structure and property features of complex aggregates assembled by polymer and organic dye molecules in microcosmic soft confined space, a three-dimensional microconfinement is constructed by W/O inverse emulsion as the site for the complex aggregation of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP). It is found that porphyrin molecules exist in emulsion droplets mainly as the deprotonated monomer form, even though the pH of the water phase is much lower than the pK(a) of TPPS in bulk (pK(a)≈ 4.7). In spatially confined circumstances, upon blending of the single-component emulsions, complex aggregates are formed due to the thermodynamic collision of emulsion droplets and the subsequent electrostatic interaction between TPPS and polymer. The resultant novel complexes possess a relatively precise structure and homogenous core consisting of a porphyrin and P4VP block. Upon emulsion-breaking, the metastable complex kinetic intermediates generated in original acidic emulsion droplets display a remarkable trend of reaggregation within a certain period of time followed by a disassociation and redispersion. Complex aggregates with some novel morphologies are observed. The final product has a core-shell structure with the electrostatic complex of deprotonized porphyrin molecules homogenously dispersing in the P4VP clew as the core and the soluble PEG as the shell. However, those complexes produced in basic emulsion droplets exhibit a relatively higher stability against further aggregation after breakage of emulsion.

Protecting enzymes against heat inactivation by temperature-sensitive polymer in confined space

“…The reason is probably that the lower boiling point and faster evaporation of the outer phase (isooctane) leads to a spreading of the droplet fringe during sample preparation. 25 However, the trend in the variation in size agrees with that displayed by DLS.…”

“…Here, we choose a confined space constructed by reverse microemulsion to solve these problems, which is inspired by our previous studies on the self-assembly of block copolymers in reverse emulsion. 24,25 Through manipulating the size of the confined space and the concentration of the polymer, aggregates possessing smaller sizes and less aggregation number were obtained in reverse emulsion, compared with normal ones in bulk aqueous solution.…”

Porphyrin in prebiotic catalysis: Ascertaining a route for the emergence of early metalloporphyrins

“…41). From previous literature, it is known that porphyrin complexes are known to predominantly form side-by-side aggregates (J-aggregates) and plane-to-plane aggregates (Haggregates) 50,[57][58][59][60][61] . Studies have also suggested that the catalytic activity of porphyrin increases upon aggregation 59,60,62 .…”

Mechanistic Process Understanding of the Biomimetic Construction of Porphyrin-Based Light-Capturing Antennas from Self-Assembled Fmoc-Blocked Peptide Templates

“…Also, as predicted in the enlarged fluorescence emission spectra (Figure 5C), the peak centered at ∼657 nm ascribed to the peptide−porphyrin adsorption complexes gradually decreased and eventually disappeared, while the peak at 713 nm decreased in intensity along with a red shift to 738 nm with an increase in the TPPS concentration, suggesting the formation of TPPS J-aggregates that increased in size with time. 27,38,39 The photoluminescence decay times of Fmoc-ChaChaGK/TPPS aggregates were obtained at an excitation wavelength of 405 nm (Figure 5D, Table 3). The short-lived component representing the Jaggregates (τ < 1 ns) increased with the increase of TPPS concentration, consitent with the result shown in their UV−vis and fluorescence emission spectra.…”