4 research outputs found
Diffusiophoresis of Polyelectrolytes in Nanodevices: Importance of Boundary
Considering the potential applications
of diffusiophoresis conducted
in nanodevices, a thorough theoretical analysis is performed for the
first time on the diffusiophoresis of a polyelectrolyte (PE) in the
presence of two representative types of boundaries: the direction
of diffusiophoresis is either normal (type I) or parallel (type II)
to a boundary, using two large parallel disks and a cylindrical pore
as an example, respectively. It is interesting to observe that due
to the effects of double-layer polarization, counterion condensation,
polarization of condensed counterions, and diffusion of co-ions across
a PE, its diffusiophoretic behavior can be influenced both quantitatively
(magnitude of mobility) and qualitatively (direction of diffusiophoresis)
by a boundary. In general, type I (II) boundary raises the diffusiophoretic
mobility of a PE toward the high (low) salt concentration side. The
results gathered provide necessary information for applications in,
for example, designing catalytic swimmers and nanopore-based biosensor
devices
Capillary Osmosis in a Charged Nanopore Connecting Two Large Reservoirs
Experimental
evidence revealed that the performance of nanopore-based
biosensing devices can be improved by applying a salt concentration
gradient. To provide a theoretical explanation for this observation
and explore the mechanisms involved, we model the capillary osmosis
(or diffusioosmosis) in a charged solid-state nanopore connecting
two large reservoirs. The effects of nanopore geometry and the reservoir
salt concentrations are examined. We show that the capillary osmotic
flow is from the high salt concentration reservoir to the low salt
concentration one, and its magnitude has a maximum as the reservoir
salt concentrations vary. In general, the shorter the nanopore and/or
the smaller its radius, the faster the osmotic flow. This flow enhances
the current recognition, and the ion concentration polarization across
nanopore openings raises the entity capture rate, thereby being capable
of improving the performance of electrophoresis-based biosensors.
The results gathered provide necessary information for designing nanopore-based
biosensor devices
Importance of Ionic Polarization Effect on the Electrophoretic Behavior of Polyelectrolyte Nanoparticles in Aqueous Electrolyte Solutions
The electrophoresis of a polyelectrolyte, an entirely porous, charged nanoparticle, in various types of aqueous electrolyte solution is modeled taking account of the presence of multiple ionic species, and its applicability is verified by the experimental data of succinoglycan in the literature. We show that, in addition to the electroosmotic flow around a polyelectrolyte, two types of competing polarization effect are also significant: counterion polarization and co-ion polarization, both of them depend largely on the thickness of the double layer. The presence of these two polarization effects yields profound and interesting electrophoretic behaviors that are distinct to polyelectrolytes. The results gathered provide necessary theoretical background for the interpretation of various types of electrophoresis data in practice. Typical examples include that of a nanopore-based sensing device used, for instance, in DNA sequencing
Targeting Tumor Associated Phosphatidylserine with New Zinc Dipicolylamine-Based Drug Conjugates
A series of zincÂ(II) dipicolylamine
(ZnDPA)-based drug conjugates
have been synthesized to probe the potential of phosphatidylserine
(PS) as a new antigen for small molecule drug conjugate (SMDC) development.
Using <i>in vitro</i> cytotoxicity and plasma stability
studies, PS-binding assay, <i>in vivo</i> pharmacokinetic
studies, and maximum tolerated dose profiles, we provided a roadmap
and the key parameters required for the development of the ZnDPA based
drug conjugate. In particular, conjugate <b>24</b> induced tumor
regression in the COLO 205 xenograft model and exhibited a more potent
antitumor effect with a 70% reduction of cytotoxic payload compared
to that of the marketed irinotecan when dosed at the same regimen.
In addition to the validation of PS as an effective pharmacodelivery
target for SMDC, our work also provided the foundation that, if applicable,
a variety of therapeutic agents could be conjugated in the same manner
to treat other PS-associated diseases