Micellization of copolymers via noncovalent interaction with TPPS and aggregation of TPPS

Abstract

Aggregation of 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) was investigated in complex micelles composed of poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP) and poly(2-(dimethylamino)ethyl methylacrylate)-b-poly(Nisopropylacrylamide) (PDMAEMA-b-PNIPAM) in aqueous solutions. The resultant complex micelles had a complex P4VP/ PDMAEMA/TPPS core and a mixed PEG/PNIPAM shell. Different noncovalent interaction modes between the porphyrin and each copolymer accomplished a co-effect on the aggregation of TPPS. The formation of aggregates was pH-dependent. At pH 3.2-6.5, TPPS existed as a mixture of H-aggregates and monomers because of the aromatic-aromatic interaction with P4VP and electrostatic interaction with PDMAEMA. The monomers translated into J-aggregates, stabilized by electrostatic interaction with the both polyelectrolyte blocks, upon decreasing the pH to 1.6. The free-base monomer was the one and only form for the dye at pH 11.0 due to aromatic stacking with the pyridyl rings.

Transformation of H-Aggregates and J-Dimers of Water-Soluble Tetrakis (4-carboxyphenyl) Porphyrin in Polyion Complex Micelles

“…From this phenomenon, it can be inferred that H-aggregates disappeared and the TCPP molecules exist in the form of J-dimers again. These results are similar to the behaviors in acidic TCPP solutions [ 44 ]. The TCPP molecules in the core of PIC micelles exist in the form of H-aggregates at a ratio < 1:4, but still exist in the form of J-dimers at a ratio > 1:4.…”

Solubilization of Charged Porphyrins in Interpolyelectrolyte Complexes: A Computer Study

“…The most common approach aimed at improving porphyrin solubility in water is the synthesis of positively or negatively charged di-, tri-, or tetra-substituted derivatives, e.g., tetratolylporphyrin substituted by pyridinium groups [23,24]. Even though the positive charge is preferable because it secures the attractive interaction with negatively charged DNA, the negatively charged 5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrin (TPPS) has been also synthesized and amply studied [1,2,25]. Recently, various porphyrin-containing systems have been designed and tested [26][27][28][29].…”

“…Gröhn and coworkers studied the electrostatic association of porphyrins with oppositely charged polyelectrolytes and described several different structures depending on the chain architecture and stiffness [30,31]. An interesting paper was published by Zhao et al [25]. The authors studied the co-micellization of poly(4-vinyl pyridine)-b-poly(ethylene oxide) (P4VP-PEO) and poly(2-(dimethylamino)ethyl methacrylate)-b-poly(N-isopropylacrylamide) (PDMAEMA-PNIPAM) with TPPS in aqueous media and found that the hydrophobic π-π interaction of pyridine cycles with porphyrin plays an important role and contributes to the formation of associates at elevated pHs when PE chains are not ionized.…”

“…However, the main driving force for the formation of nanoparticles with IPEC cores derives neither from electrostatics nor from other interactions but from a considerable increase in entropy upon the liberation of small and mobile counterions, which must stay close to PE chains to compensate for the PE charge and which, upon the formation of electrostatic associates, can escape into bulk solution. Charged porphyrins are relatively large molecules and contain conjugated hydrophobic rings which interact conveniently with polyelectrolytes bearing aromatic rings as pendant groups (e.g., P4PV [25]). They are multiply charged and can serve as electrostatic crosslinking agents, and their incorporation into IPEC liberates small ions.…”

Preparation of Novel Porphyrin Nanomaterials Based on the pH-Responsive Shape Evolution of Porphyrin Microspheres

“…Porphyrins have received much attention because of their excellent spectroscopic, photophysical, photochemical, and assembly properties, such as high absorption coefficients and remarkable chemical stability. , Owing to their unique planar and rigid molecular geometry and easily modified periphery, porphyrins are widely utilized in supramolecular chemistry. Driven by noncovalent interactions such as π–π stacking, , hydrogen bonding, electrostatic interactions, and metal coordination, porphyrins can self-assemble into various nanostructures, enriching their photophysical and photochemical properties. − …”