TY - JOUR
T1 - Rapid Internalization of Nanoparticles by Human Cells at the Single Particle Level
AU - Richards, Ceri J.
AU - Burgers, Thomas
AU - Vlijm, Rifka
AU - Roos, Wouter H.
AU - Åberg, Christoffer
PY - 2023/9/12
Y1 - 2023/9/12
N2 - Nanoparticle uptake by cells has been studied for applications both in nanomedicine and in nanosafety. While the majority of studies have focused on the biological mechanisms underlying particle internalization, less attention has been given to questions of a more quantitative nature, such as how many nanoparticles enter cells and how rapidly they do so. To address this, we exposed human embryonic kidney cells to 40–200 nm carboxylated polystyrene nanoparticles and the particles were observed by live-cell confocal and super-resolution stimulated emission depletion fluorescence microscopy. How long a particle remained at the cell membrane after adsorbing onto it was monitored, distinguishing whether the particle ultimately desorbed again or was internalized by the cell. We found that the majority of particles desorb, but interestingly, most of the particles that are internalized do so within seconds, independently of particle size. As this is faster than typical endocytic mechanisms, we interpret this observation as the particles entering via an endocytic event that is already taking place (as opposed to directly triggering their own uptake) or possibly via an as yet uncharacterized endocytic route. Aside from the rapidly internalizing particles, a minority of particles remain at the membrane for tens of seconds to minutes before desorbing or being internalized. We also followed particles after cell internalization, observing particles that appeared to exit the cell, sometimes as rapidly as within tens of seconds. Overall, our results provide quantitative information about nanoparticle cell internalization times and early trafficking.
AB - Nanoparticle uptake by cells has been studied for applications both in nanomedicine and in nanosafety. While the majority of studies have focused on the biological mechanisms underlying particle internalization, less attention has been given to questions of a more quantitative nature, such as how many nanoparticles enter cells and how rapidly they do so. To address this, we exposed human embryonic kidney cells to 40–200 nm carboxylated polystyrene nanoparticles and the particles were observed by live-cell confocal and super-resolution stimulated emission depletion fluorescence microscopy. How long a particle remained at the cell membrane after adsorbing onto it was monitored, distinguishing whether the particle ultimately desorbed again or was internalized by the cell. We found that the majority of particles desorb, but interestingly, most of the particles that are internalized do so within seconds, independently of particle size. As this is faster than typical endocytic mechanisms, we interpret this observation as the particles entering via an endocytic event that is already taking place (as opposed to directly triggering their own uptake) or possibly via an as yet uncharacterized endocytic route. Aside from the rapidly internalizing particles, a minority of particles remain at the membrane for tens of seconds to minutes before desorbing or being internalized. We also followed particles after cell internalization, observing particles that appeared to exit the cell, sometimes as rapidly as within tens of seconds. Overall, our results provide quantitative information about nanoparticle cell internalization times and early trafficking.
KW - endocytosis
KW - residence time
KW - confocal microscopy
KW - STED microscopy
KW - human embryonic kidney cells
KW - polystyrene nanoparticles
UR - http://www.ncbi.nlm.nih.gov/pmc/articles/pmc10510712/
U2 - 10.1021/acsnano.3c01124
DO - 10.1021/acsnano.3c01124
M3 - Article
SN - 1936-0851
VL - 17
SP - 16517
EP - 16529
JO - Acs Nano
JF - Acs Nano
IS - 17
ER -