self-assembled monolayer [50] or hydrophobic/van der Waals interaction over oleic
acid-modified nanoparticles [51] was used to make facile preparation. The latter has
adopted the same encapsulation methods as was in the report by Jeong’s group [42].
Multiple steps of binding the surface-modifiers had become the essential point of
concern. In every case, protein adsorption could be avoided [9, 10, 53] and also the
non-specific uptake by tumor [35] or macrophage cells [9]. Functional residues at
the end of sulfobetaine or carboxybetaine were also proposed for further modification to let the nanoparticles to have targeting capability in vivo after systemic
administration.
18.3 PEGylation/Zwitterion-Coating Countering Protein
Corona Formation
Hydrophobic nanoparticles mimics invading infective microorganism and cause
aggregation once they meet plasma, whose water solution expels nanoparticles to
make bigger particles and then whose many proteins wrap up the nanoparticles.
Beside hydrophobic nanoparticles, hydrophilic nanoparticles also are wrapped up
by plasma proteins in a non-random way so that their identity is now determined
after the corona protein surrounded the nanoparticles. It was easy to divide the
proteins into hard (having higher affinity) and soft (competitively bound and
reversible or exchangeable). And soft corona proteins are easily changed with other
soft corona proteins, however, this concept was challenged by recent findings by
Tenzer and colleagues [20], where the characteristic corona was established within
1 min after mixing or injection, the constituent corona proteins did not change
much and at most change only in quantitative terms. Though we don’t know that
this is universally applied to nanoparticles and plasma of healthy or diseased
humans, if true, it came to be easy to characterize the systemically administered
nanoparticles [21] and to predict the behavior of these nanoparticles in vivo. The
behavior here means biodistribution in general and target disposition which will be
affected by the determinants of physiology and immune response.
Now if we try to understand the characteristics of a kind of nanoparticles, we
need to determine size, surface charge, density and shape of the surface modifier
and also adsorbed proteins, i.e. corona. Adding corona to the model to predict
nanoparticles’ interaction with target cells or non-target scavenger cells improved
the prediction up to 50% [21]. By the way, these reports about corona modification
of nanoparticles were sometimes investigated in in vitro conditions, or in other
times, in in vivo but without optimized hydrophilization. Few reports [23, 28] dealt
with the effect of concomitant PEGylation and corona of the nanoparticles on their
targeted cellular uptake [23] and stealth effects [28]. In the former report, the
investigators observed the reduced receptor binding due to corona proteins wrapping anti-MUC1-targeted PEGylated liposome. Or in the latter report corona proteins rather helped nanoparticles enjoy stealth effect. PEG or other PPE-coated
18 Polyethylene Glycolation (PEGylation) and the Similar
339
acid-modified nanoparticles [51] was used to make facile preparation. The latter has
adopted the same encapsulation methods as was in the report by Jeong’s group [42].
Multiple steps of binding the surface-modifiers had become the essential point of
concern. In every case, protein adsorption could be avoided [9, 10, 53] and also the
non-specific uptake by tumor [35] or macrophage cells [9]. Functional residues at
the end of sulfobetaine or carboxybetaine were also proposed for further modification to let the nanoparticles to have targeting capability in vivo after systemic
administration.
18.3 PEGylation/Zwitterion-Coating Countering Protein
Corona Formation
Hydrophobic nanoparticles mimics invading infective microorganism and cause
aggregation once they meet plasma, whose water solution expels nanoparticles to
make bigger particles and then whose many proteins wrap up the nanoparticles.
Beside hydrophobic nanoparticles, hydrophilic nanoparticles also are wrapped up
by plasma proteins in a non-random way so that their identity is now determined
after the corona protein surrounded the nanoparticles. It was easy to divide the
proteins into hard (having higher affinity) and soft (competitively bound and
reversible or exchangeable). And soft corona proteins are easily changed with other
soft corona proteins, however, this concept was challenged by recent findings by
Tenzer and colleagues [20], where the characteristic corona was established within
1 min after mixing or injection, the constituent corona proteins did not change
much and at most change only in quantitative terms. Though we don’t know that
this is universally applied to nanoparticles and plasma of healthy or diseased
humans, if true, it came to be easy to characterize the systemically administered
nanoparticles [21] and to predict the behavior of these nanoparticles in vivo. The
behavior here means biodistribution in general and target disposition which will be
affected by the determinants of physiology and immune response.
Now if we try to understand the characteristics of a kind of nanoparticles, we
need to determine size, surface charge, density and shape of the surface modifier
and also adsorbed proteins, i.e. corona. Adding corona to the model to predict
nanoparticles’ interaction with target cells or non-target scavenger cells improved
the prediction up to 50% [21]. By the way, these reports about corona modification
of nanoparticles were sometimes investigated in in vitro conditions, or in other
times, in in vivo but without optimized hydrophilization. Few reports [23, 28] dealt
with the effect of concomitant PEGylation and corona of the nanoparticles on their
targeted cellular uptake [23] and stealth effects [28]. In the former report, the
investigators observed the reduced receptor binding due to corona proteins wrapping anti-MUC1-targeted PEGylated liposome. Or in the latter report corona proteins rather helped nanoparticles enjoy stealth effect. PEG or other PPE-coated
18 Polyethylene Glycolation (PEGylation) and the Similar
339