Colloidal stability of nano-sized particles in the peritoneal fluid: Towards optimizing drug delivery systems for intraperitoneal therapy

Abstract

Intraperitoneal (IP) administration of nano-sized delivery vehicles containing small interfering RNA (siRNA) is recently gaining attention as an alternative route for the efficient treatment of peritoneal carcinomatosis. The colloidal stability of nanomatter following IP administration has, however, not been thoroughly investigated yet. Here, enabled by advanced microscopy methods such as Single Particle Tracking (SPT) and Fluorescence Correlation Spectroscopy (FCS), we follow the aggregation and cargo release of nano-scaled systems directly in peritoneal fluids from healthy mice and ascites fluid from a patient diagnosed with peritoneal carcinomatosis. The colloidal stability in the peritoneal fluids was systematically studied in function of the charge (positive or negative) and Poly-Ethylene Glycol (PEG) degree of liposomes and polystyrene nanoparticles, and compared to human serum. Our data demonstrate strong aggregation of cationic and anionic nanoparticles in the peritoneal fluids, while only slight aggregation was observed for the PEGylated ones. PEGylated liposomes, however, lead to a fast and premature release of siRNA cargo in the peritoneal fluids. Based on our observations, we reflect on how to tailor improved delivery systems for IP therapy.

Disregarded Effect of Biological Fluids in siRNA Delivery: Human Ascites Fluid Severely Restricts Cellular Uptake of Nanoparticles

“…In our hands fSPT has proven to be superior over DLS to study aggregation of nanoparticles in biological fluids 7,[11][12][13] . Figure 3a shows the size distributions of the cationic LPXs incubated in Based on the data in Figure 4c, it is clear that very severe aggregation occurs in ascites fluids for LF-LPXs.…”

“…Both the protein composition of the biofluid and the surface properties of the nanoparticles will determine the composition of the protein corona that is eventually formed. We have previously shown that the protein concentration in human ascites fluid is half the concentration of proteins present in human serum, while the protein composition of human ascites fluid is very similar to human serum, with albumin as main fraction (62%) 7 . We hypothesize that the poor uptake observed following incubation of cationic LPXs and PEGylated LPXs in the ascites fluid results from the surface coating of these formulations with negatively charged proteins 18 .…”

“…Fluorescence Correlation Spectroscopy (FCS) is a microscopy-based technique that monitors the fluorescence intensity fluctuations of (fluorescent) molecules diffusing in and out of the focal volume of a confocal microscope 7,10 . Single color FCS measurements were performed on LPXs containing 30% Cy5 siRNA, with a +/-charge ratio of 8.…”

“…In our previous study 7 , we have shown that dynamic light scattering (DLS) is not an ideal technique for quantifying the extent of aggregation of nanocarriers in (undiluted) ascites fluids, simply due to light scattering that results from the high amount of proteins in such samples. In our hands fSPT has proven to be superior over DLS to study aggregation of nanoparticles in biological fluids 7,[11][12][13] .…”

“…siRNA) in an intact form while circulating in the biological fluids of the body. Also, pre-mature release of the siRNA from the nanoparticles and aggregation of siRNA nanoparticles in biological fluids are referred to as extracellular barriers for siRNA delivery 7 . While it is possible to determine the overall biological activity (i.e.…”