Influence of Magnetic Micelles on Assembly and Deposition of Porphyrin J-Aggregates.

Maria Angela Castriciano,Salvatore Patanè,Mariachiara Trapani,Elisabetta Fanizza,Luigi Monsù Scolaro,Federica Rizzi,Nicoletta Depalo,Andrea Romeo

doi:10.3390/nano10020187

Abstract

Clusters of superparamagnetic iron oxide nanoparticles (SPIONs) have been incorporated into the hydrophobic core of polyethylene glycol (PEG)-modified phospholipid micelles. Two different PEG-phospholipids have been selected to guarantee water solubility and provide an external corona, bearing neutral (SPIONs@PEG-micelles) or positively charged amino groups (SPIONs@NH2-PEG-micelles). Under acidic conditions and with specific mixing protocols (porphyrin first, PF, or porphyrin last, PL), the water-soluble 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) forms chiral J-aggregates, and in the presence of the two different types of magnetic micelles, an increase of the aggregation rates has been generally observed. In the case of the neutral SPIONs@PEG-micelles, PL protocol affords a stable nanosystem, whereas PF protocol is effective with the charged SPIONs@NH2-PEG-micelles. In both cases, chiral J-aggregates embedded into the magnetic micelles (TPPS@SPIONs@micelles) have been characterized in solution through UV/vis absorption and circular/linear dichroism. An external magnetic field allows depositing films of the TPPS@SPIONs@micelles that retain their chiroptical properties and exhibit a high degree of alignment, which is also confirmed by atomic force microscopy.

Highlights

Spintronics open a new scenario for the fabrication of efficient devices and refer to electronics based on the electron spin, which is typically controlled by magnetic fields or by ferro-/paramagnetic materials
We investigated on the ability of superparamagnetic iron oxide nanoparticles (SPIONs)-loaded micelles to efficiently promote the formation of hybrid TPPS@SPIONs@micelle J-aggregates
The aqueous dispersibility of the hydrophobic SPIONs was guaranteed by the formation of SPIONs encapsulating micelles composed of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (poly(ethylene glycol))-2000] (PEG-2-PE), or a mixture of PEG-2-PE and amine 1,2-distearoyl-sn-glycero-3-phosphoethanolamineN-[amino(polyethylene glycol)-2000] (DSPE-PEG-amine], bearing PEG chains and amine terminated PEG chains, respectively (Figure 1) [66,75]

Summary

Introduction

Spintronics open a new scenario for the fabrication of efficient devices and refer to electronics based on the electron spin, which is typically controlled by magnetic fields or by ferro-/paramagnetic materials. Organic molecules were proposed as a spin filter for “molecular spintronics” due to their relatively longer coherent spin lifetimes and spin transport distances, resulting from weak spin–orbit coupling and weak hyperfine interactions [1,2] The latter may allow the development of nanoscale devices with improved performance or new functionalities. We anticipate that the SPION-loaded micelles are able to efficiently trigger the growth of TPPS J-aggregates under proper experimental conditions and reagent mixing order protocol This assembling strategy allows conjugating the magnetic properties of the SPIONs@micelles with the chiral optical properties of the J-aggregates, obtaining hybrid architectures in solution and on solid state by means of an applied magnetic field.

Methods

Results

Conclusion