
368 Nanosensors: Physical, Chemical, and Biological
photobleaching. Moreover, the fabrication process confers homogeneous dis-
tribution of the entrapped dyes within the sensors allowing spatial resolu-
tion and continuity to ratiometric measurements in vitro.
How are PEBBLEs introduced into the cells? This is an important issue. A
variety of methods to introduce PEBBLEs to a range of cell types have been
employed, including functionalization with cell-penetrating peptides (CPPs),
endocytosis (cellular process where cells absorb molecules or substances
from outside the cell by surrounding and overwhelming them with the cell
membrane ...