**4. Conclusions**

J-aggregates of TPPS porphyrin are interesting nanomaterials, since depending on the experimental conditions and templating agents, they can be prepared in a variety of different morphologies. The use of magnetic micelles offers a way to obtain hybrid organic/inorganic nanosystems that conjugate the properties of each constituent component. The porphyrin nanoaggregates exhibit peculiar extinction bands, with enhanced resonant light-scattering effects [34], and chiroptical properties that can spontaneously appear or be induced by doping them with a proper chiral reagen<sup>t</sup> [40]. The SPIONs micelles, with the two different capping phospholipids, while allowing for the water solubility of the inorganic cluster core, afford a hydrophilic surface where eventually TPPS can nucleate, leading to the final J-aggregates. The presence of an amino-terminated chain in the case of SPIONs@NH2- PEG-micelles determines a distinct change in the supramolecular assembling kinetics of TPPS. Furthermore, the nature of the terminal PEG chain on the phospholipid influences the way in which the two different mixing protocols control the formation of stable nanosystems. In both cases, taking advantage of the magnetic properties of SPIONs, it is possible to drive the deposition of TPPS J-aggregates embedded into the micelles onto surface, thus achieving a high level of alignment into the film. Considering the optical and chiroptical response, still conserved in the solid phase, and their magnetic properties, we expect that these nanosystems could find potential applications in a variety of fields, including spintronics, optoelectronics and theranostics.

**Author Contributions:** Conceptualization, L.M.S. and M.A.C.; investigation, M.T., N.D., E.F., F.R., and S.P.; data curation, M.T., A.R., E.F., and M.A.C.; writing—original draft preparation, M.A.C. and N.D.; writing—review and editing, L.M.S., M.A.C., A.R., N.D., and M.T.; visualization, A.R., E.F., and S.P.; Authorship must be limited to those who have contributed substantially to the work reported. All authors have read and agree to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
