Spectroscopic investigation on porphyrins nano-assemblies onto gold nanorods

Mariachiara Trapani; Giovanna De Luca; Andrea Romeo; Maria Angela Castriciano; Luigi Monsù Scolaro

doi:10.1016/j.saa.2016.09.025

Spectroscopic investigation on porphyrins nano-assemblies onto gold nanorods

Spectrochim Acta A Mol Biomol Spectrosc. 2017 Feb 15:173:343-349. doi: 10.1016/j.saa.2016.09.025. Epub 2016 Sep 22.

Authors

Mariachiara Trapani¹, Giovanna De Luca², Andrea Romeo³, Maria Angela Castriciano⁴, Luigi Monsù Scolaro⁵

Affiliations

¹ CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D'Alcontres, 31 98166 Messina, Italy.
² Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina and C.I.R.C.M.S.B, V.le F. Stagno D'Alcontres, 31 98166 Messina, Italy; CNR-IPCB Istituto dei Polimeri, Compositi e Biomateriali - P.le Enrico Fermi 1, 80055 Portici (NA), Italy.
³ CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D'Alcontres, 31 98166 Messina, Italy; Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina and C.I.R.C.M.S.B, V.le F. Stagno D'Alcontres, 31 98166 Messina, Italy.
⁴ CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D'Alcontres, 31 98166 Messina, Italy. Electronic address: castriciano@pa.ismn.cnr.it.
⁵ CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D'Alcontres, 31 98166 Messina, Italy; Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina and C.I.R.C.M.S.B, V.le F. Stagno D'Alcontres, 31 98166 Messina, Italy. Electronic address: lmonsu@unime.it.

PMID: 27685002
DOI: 10.1016/j.saa.2016.09.025

Abstract

The interaction between gold nanorods (Au NRs), synthesized by a conventional seeded growth protocol, and the anionic tetrakis-(4-sulfonatophenyl)porphyrin (TPPS₄) has been investigated through various spectroscopic techniques. At neutral pH, the formation of H-aggregates and the inclusion of porphyrin monomers in CTAB micelles covering the nanorods have been evidenced. Under mild acidic conditions (pH=3) a nano-hybrid assembly of porphyrin J-aggregates and Au NRs has been revealed. For the sake of comparison, Cu(II) and Zn(II) metal porphyrin derivatives as well as a cationic porphyrin have been studied in the same experimental conditions, showing that: i) CuTPPS₄ forms porphyrin H-dimers onto the Au NRs; ii) ZnTPPS₄ undergoes to demetallation, followed by acidification of the central core and eventually aggregation onto Au NRs; iii) cationic porphyrin does not interact with Au NRs.

Keywords: Aggregation; Gold nanorods; Porphyrin; Spectroscopic characterization.