Towards an Artificial Replication of the Nuclear Pore Complex
Typ
Examensarbete för masterexamen
Program
Nanotechnology (MPNAT), MSc
Publicerad
2022
Författare
Medin, Jesper
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The nuclear pore complex acts as a selective barrier between the nucleus and the cytoplasm
of a eukaryotic cell, allowing for selective and active transport of biomolecules
across the nuclear envelope. The selectivity of the transport is facilitated by shuttle
proteins that are able to bind specifically to cargo proteins, actively guide them
through the nuclear envelope, and release them on the other side.
In this work, an artificial replication of the nuclear transport using poly(methacrylic
acid) (PMAA) and poly(N-(2-hydroxyethyl) acrylamide) (PHEAA) as a shuttle and
barrier respectively was developed to allow for selective transport of macromolecules
through solid-state nanopores. PHEAA was grafted from gold by atom transfer
radical polymerisation (ATRP). In water, hydrated "polymer brushes" have been
reported to serve as entropic barriers against proteins and other macromolecules.
Intermolecular interaction studies using surface plasmon resonance (SPR) and quartz
crystal microbalance dissipation (QCM-D) showed that PMAA was able to interact
with PHEAA and insert itself into the brush. Further, the interaction was shown to
be controllable by changing the pH. This changed PMAA from a protonated state
where it could continuously form and break hydrogen bonds with the PHEAA brush,
to a charged state where it could not.
Fluorescence imaging showed that PMAA with covalently attached fluorescent cargo
could undergo pH dependent diffusion through nanopores covered with PHEAA. At
a pH of 7.5 PMAA was charged and would be blocked by the polymer brush. At a pH
of 4.0 PMAA was protonated and would diffuse through the nanopore and carry the
fluorescence cargo with it to the other side. This demonstrated that the artificial
system could mimic the key features of the nuclear pore complex and selectively
transport molecular cargo across a solid state nanopore.
Beskrivning
Ämne/nyckelord
artificial biology , nanotechnology , polymer brushes , soft matter