Quantitative phase microscopy is applied to image temporal changes in the refractive index (RI) distributions of solutions created by microbicidal films undergoing hydration. We present a novel method of using an engineered polydimethylsiloxane structure as a static phase reference to facilitate calibration of the absolute RI across the entire field. We present a study of dynamic structural changes in microbicidal films during hydration and subsequent dissolution. With assumptions about the smoothness of the phase changes induced by these films, we calculate absolute changes in the percentage of film in regions across the field of view.
The effectiveness of microbicidal gels, topical products developed to prevent infection by sexually transmitted diseases
including HIV/AIDS, is governed by extent of gel coverage, pharmacokinetics of active pharmaceutical ingredients
(APIs), and integrity of vaginal epithelium. While biopsies provide localized information about drug delivery and tissue
structure, <i>in vivo</i> measurements are preferable in providing objective data on API and gel coating distribution as well as
tissue integrity. We are developing a system combining confocal fluorescence microscopy with optical coherence
tomography (OCT) to simultaneously measure local concentrations and diffusion coefficients of APIs during transport
from microbicidal gels into tissue, while assessing tissue integrity. The confocal module acquires 2-D images of
fluorescent APIs multiple times per second allowing analysis of lateral diffusion kinetics. The custom Fourier domain
OCT module has a maximum a-scan rate of 54 kHz and provides depth-resolved tissue integrity information coregistered
with the confocal fluorescence measurements. The combined system is validated by imaging phantoms with a
surrogate fluorophore. Time-resolved API concentration measured at fixed depths is analyzed for diffusion kinetics.
This multimodal system will eventually be implemented <i>in vivo</i> for objective evaluation of microbicide product
Methods for the optimization of a/LCI for clinical use are presented. First, the use of the T-matrix light
scattering model to simulate scattering from spheroidal particles is presented as a more appropriate simulation of
cell nuclei scattering than the previously used Mie theory. In addition, the use of a broadband light source with a
bandwidth greater than 50nm similar to those utilized in OCT applications is demonstrated. Accurate sizing of
scatterers in tissue phantoms containing stretched and unstretched polystyrene microspheres along with
measurements of unstretched polystyrene microspheres in solution are presented, demonstrating advances in system
performance and design. In addition, preliminary human in vivo esophageal tissue data are presented.