Assessing the mechanical behavior
of nano- and micron-scale
particles
with complex shapes is fundamental in drug delivery. Although different
techniques are available to quantify the bulk stiffness in static
conditions, there is still uncertainty in assessing particle deformability
in dynamic conditions. Here, a microfluidic chip is designed, engineered,
and validated as a platform to assess the mechanical behavior of fluid-borne
particles. Specifically, potassium hydroxide (KOH) wet etching was
used to realize a channel incorporating a series of micropillars (filtering
modules) with different geometries and openings, acting as microfilters
in the direction of the flow. These filtering modules were designed
with progressively decreasing openings, ranging in size from about
5 down to 1 μm. Discoidal polymeric nanoconstructs (DPNs), with
a diameter of 5.5 μm and a height of 400 nm, were realized with
different poly(lactic-co-glycolic acid) (PLGA) and
poly(ethylene glycol) (PEG) ratios (PLGA/PEG), namely, 5:1 and 1:0,
resulting in soft and rigid particles, respectively. Given the peculiar
geometry of DPNs, the channel height was kept to 5 μm to limit
particle tumbling or flipping along the flow. After thorough physicochemical
and morphological characterization, DPNs were tested within the microfluidic
chip to investigate their behavior under flow. As expected, most rigid
DPNs were trapped in the first series of pillars, whereas soft DPNs
were observed to cross multiple filtering modules and reach the micropillars
with the smallest opening (1 μm). This experimental evidence
was also supported by computational tools, where DPNs were modeled
as a network of springs and beads immersed in a Newtonian fluid using
the smoothed particle hydrodynamics (SPH) method. This preliminary
study presents a combined experimental–computational framework
to quantify, compare, and analyze the characteristics of particles
having complex geometrical and mechanical attributes under flow conditions.