Visualization and characterization of metallo-aggregates using multi-photon microscopy

Abstract

A simple and cost-effective method based on multi-photon microscopy is presented for the preliminary screening of the general morphology, size range and heterogeneity of Ir(iii) nano-aggregate formulations.

Fig. 1. (A) Schematic representation of the mixed metallo-nano-aggregates NA1 composed of DPPC, CTAB and Ir(iii) complex 1. CTAB is not shown for clarity. Model 1 represents rod-like micelles and model 2 elongated vesicles. UV/Vis absorption, OPE and MPE spectra of (B) complex 1 in DMSO : H₂O (1 : 99) and (C) the mixed nano-aggregates NA1 in H₂O. λ_{exc, OPE} = 350 nm and λ_{exc, MPE} = 900 nm.

Fig. 2. (A) Multi-photon microscopy images of the Ir(iii) nano-aggregates NA1; (B) bright field images; (C) calculated length and width of the nano-aggregates NA1 using the ellipse approximation and (D) length and width size distribution.

Fig. 3. AFM images of nano-aggregates NA1 (A) display of several large and smaller nano-aggregates; (B) higher resolution image of one rectangular nano-aggregate.

Fig. 4. Stacked multi-photon microscopy images of Ir(iii) nano-aggregates NA1. (A) Top view (B) horizontal view (z-plane).

Fig. 5. Multi-photon microscopy images of 1 in MeOH, MeOH : H₂O (80 : 20, v/v) and H₂O. The corresponding MPE spectra are shown below. The dotted line indicates the emission maximum of NA1.