Purpose:
Pilot experiments (figure 1) indicate that functionalized nanoparticles may be used to achieve molecular contrast in optical imaging techniques such as Optical Coherence Tomography (OCT). We have recently started the development of retinal tissue simulating phantoms in order to estimate the minimal concentration of (gold) nanoparticles needed for NAOMI contrast enhancement in retinal tissue.
Methods:
Ultra thin layered (300 υm) silicone phantoms (Sylgard elastomer) are fabricated containing different concentrations of TiO2 particles to obtain scattering properties comparable with retinal tissue. Perfect homogeneity is obtained by applying a vacuum pump in combination with a homogenizer during curing of the silicone. Thin layered phantoms containing retinal pigment epithelium (RPE) cells and colloidal gold nanoparticles are also developed. All phantoms are characterized by their bulk refractive index and optical attenuation coefficients using OCT measurements and are compared to clinical OCT images obtained with a conventional time-domain OCT system.
Results:
A range of retinal tissue simulating phantoms could be fabricated and optically characterized, including layers containing RPE cells and colloidal gold nanoparticles. The sensitivity of the OCT imaging system with respect to the nanoparticle concentration will be presented.
Conclusions:
NAOMI adds cellular and molecular information to optical imaging techniques (e.g. OCT). To elucidate sensitivity and toxicity issues associated with these techniques, it is vital to develop tissue simulating optical phantoms. In this contribution, we developed and characterized such phantoms.
Keywords: optical properties • retinal pigment epithelium