Water Dispersible and Biocompatible Porphyrin-Based Nanospheres for Biophotonics Applications: A Novel Surfactant and Polyelectrolyte-Based Fabrication Strategy for Modifying Hydrophobic Porphyrins

The hydrophobility of most porphyrin
and porphyrin derivatives has limited their applications in medicine
and biology. Herein, we developed a novel and general strategy for
the design of porphyrin nanospheres with good biocompatibility and
water dispersibility for biological applications using hydrophobic
porphyrins. In order to display the generality of the method, we used
two hydrophobic porphyrin isomers as starting material which have
different structures confirmed by an X-ray technique. The porphyrin
nanospheres were fabricated through two main steps. First, the uniform
porphyrin nanospheres stabilized by surfactant were prepared by an
interfacially driven microemulsion method, and then the layer-by-layer
method was used for the synthesis of polyelectrolyte-coated porphyrin
nanospheres to reduce the toxicity of the surfactant as well as improve
the biocompatibility of the nanospheres. The newly fabricated porphyrin
nanospheres were characterized by TEM techniques, the electronic absorption
spectra, photoluminescence emission spectra, dynamic light scattering,
and cytotoxicity examination. The resulting nanospheres demonstrated
good biocompatibility, excellent water dispersibility and low toxicity.
In order to show their application in biophotonics, these porphyrin
nanospheres were successfully applied in targeted living cancer cell
imaging. The results showed an effective method had been explored
to prepare water dispersible and highly stable porphyrin nanomaterial
for biophotonics applications using hydrophobic porphyrin. The approach
we reported shows obvious flexibility because the surfactants and
polyelectrolytes can be optionally selected in accordance with the
characteristics of the hydrophobic material. This strategy will expand
the applications of hydrophobic porphyrins owning excellent properties
in medicine and biology.