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

Abstract

The shapes and properties of self-assembled materials can be adjusted easily using environmental stimuli. Yet, the stimulus-triggered shape evolution of organic microspheres in aqueous solution has rarely been reported so far. Here, a novel type of poly(allylamine hydrochloride)-g-porphyrin microspheres (PAH-g-Por MPs) was prepared by a Schiff base reaction between 2-formyl-5,10,15,20-tetraphenylporphyrin (Por-CHO) and PAH doped in 3.5-μm CaCO3 microparticles, followed by template removal. The PAH-g-Por MPs had an average diameter of 2.5 μm and could be transformed into one-dimensional nanorods (NRs) and wormlike nanostructures (WSs) after being incubated for different times in pH 1-4 HCl solutions. The rate and degree of hydrolysis had a significant effect on the formation and morphologies of the nanorods. The NRs@pH1, NRs@pH2, and NRs@pH3 were all composed of the released Por-CHO and the unhydrolyzed PAH-g-Por because of the incomplete hydrolysis of the Schiff base. However, the WSs@pH4 were formed by a pure physical shape transformation, because they had the same composition as the PAH-g-Por MPs and the Schiff base bonds were not hydrolyzed. The self-assembled NRs and WSs exhibited good colloidal stability and could emit stable red fluorescence over a relatively long period of time.

Cooperative self-assembly of porphyrins with polymers possessing bioactive functions

“…In parallel with the efforts to fabricate porphyrin/polymer composites covalently, [26][27][28] many researchers have constructed assemblies through the cooperative assembly of porphyrins with polymers. Weak interactions, such as hydrophobic, electrostatic, coordination interaction, hydrogen bonding, and host-guest recognition, are the main driving forces of the self-assembly.…”

Novel morphologies of poly(allyamine hydrochloride)–methotrexate nanoassemblies for methotrexate delivery

“…microspheres, onedimensional nanorods (NRs), and wormlike nanostructures (WSs)). 29 Most typically, PAH was oen used to construct multilayers or nanocapsules with poly(sodium 4-styrene sulfonate) (PSS) through the layer-by-layer assembly based on the electrostatic interaction. [30][31][32][33][34][35][36][37] The resultant PAH nanocapsules also presented biocompatibility, non-toxicity, good encapsulation and controlled release behavior, thus being widely used for gene and drug delivery purposes as well as other biomedical applications.…”