Presentation day

Tuesday  4:20 PM

 

TITLE

Protein-shell and polymer-core nanoball 

 

Abstract

We have synthesized (nitrilotriacetic acid)-end-functionalized polystyrene (NTA-PS) for the
controlled bioconjugation with histidine-tagged green fluorescence proteins (His6-GFP). NTA-PS was
prepared using initiators containing t-butyl protected NTA moiety via atom transfer radical polymerization
(ATRP) of styrene; the protected t-butyl group was subsequently removed at the α-chain end of
polystyrene. The structure of NTA-PS was characterized using 1H NMR, 13C NMR, and GPC. NTA chain
ends of the polystyrenes were complexed with Ni2+ to produce Ni-NTA-PS, of which the specific binding
properties were studied by forming spherical aggregates with His6-GFP in aqueous phase. The reversible
association of His6-GFP with Ni-NTA-PS was controlled with imidazole and monitored with fluorescence
microscope. Again, we reported a simple method for the construction and control of polymer-protein coreshell
hybrid micellar aggregates in situ from Ni-NTA-PS and His6-GFP through NTA-Ni/His interaction in
water/DMF (DMF 4 vol %) at physiological pH. The generality of the approach was demonstrated by using
His-tagged GFP and His-tagged lipases. A possible mechanism for the formation of such polymer-protein
core-shell hybrid aggregates is also described. We have also studied the encapsulation of various
nanoparticles (NPs) for aqueous dispersion and selective separation of His-tag proteins using NTA-PS. The
generality of encapsulation method was demonstrated by incorporating semiconductor, magnetic and metal
NPs in the nanocarriers. The complexation of Ni2+ with NTA on the surface of nanocarriers containing
magnetic NPs (γ-Fe2O3) enabled us to separate His-tagged proteins selectively from a multicomponent
solution including a cell lysate using a magnet.