Identification of peptide coatings that enhance diffusive transport of nanoparticles through the tumor microenvironment

Rashmi Mohanty; Xinquan Liu; Jae You Kim; Xiujuan Peng; Sahil Bhandari; Jasmim Leal; Dhivya Arasappan; Dennis C. Wylie; Tony Dong; Debadyuti Ghosh

Next, we confirmed that selected and motif peptide-presenting phage exhibited improved diffusion through the tumor-mimetic ECM compared to control phage. Here, we measured the diffusion of the peptide-presenting phage through tumor-like ECM using a fluorescence-based microfluidic channel diffusion assay, as described elsewhere 66 . We prepared the ECM within the channel of a microfluidic chamber µ-slide (Figure 3a) . The tumor ECM in the channel provides a semi-infinite barrier to test the diffusivity of the phage clones. The encapsulated DNA of the phage was fluorescently labeled to avoid surface labeling of phage, which could change the surface properties of the phage and affect interaction and transport through the ECM. Phage were added to the input reservoir, and an equal volume of PBS is added to the output reservoir to maintain the hydrostatic pressure and to achieve a concentration gradient through the channels. Fluorescent images of the channel were acquired at different time points and processed to identify the fluorescence intensity at each time point over the distance of the entire channel (Figure 3b) . The normalized intensity value over the channel length and the entire diffusion time was used for nonlinear curve fitting with the Fick's second law of diffusion to calculate the diffusion coefficient of each clone using a customized MATLAB script ( Figure S2 ).