Encapsidated Atom-Transfer Radical Polymerization in Qβ Virus-like Nanoparticles

Abstract

Virus-like particles (VLPs) are unique macromolecular structures that hold great promise in biomedical and biomaterial applications. The interior of the 30 nm-diameter Qβ VLP was functionalized by a three-step process: (1) hydrolytic removal of endogenously packaged RNA, (2) covalent attachment of initiator molecules to unnatural amino acid residues located on the interior capsid surface, and (3) atom-transfer radical polymerization of tertiary amine-bearing methacrylate monomers. The resulting polymer-containing particles were moderately expanded in size; however, biotin-derivatized polymer strands were only very weakly accessible to avidin, suggesting that most of the polymer was confined within the protein shell. The polymer-containing particles were also found to exhibit physical and chemical properties characteristic of positively charged nanostructures, including the ability to easily enter mammalian cells and deliver functional small interfering RNA.

Click Chemistry in Complex Mixtures: Bioorthogonal Bioconjugation

“…Such operations as the immobilization, labeling, or capture of proteins, nucleic acids, and polysaccharides (Moses and Moorhouse, 2007) benefit from the small size and unobtrusive nature of the terminal alkyne and azide moieties. Among many other applications, the CuAAC process has been used to label the outer (Banerjee et al, 2010; Banerjee et al, 2011; Hong et al, 2009b; Wang et al, 2003b) and inner (Abedin et al, 2009; Hovlid et al, 2014) surfaces of azide- and alkyne-functionalized virus particles, modify proteins in vitro and in vivo (Deiters et al, 2003; Liu and Schultz, 2010; Ngo and Tirrell, 2011), tag azide-modified lipids (Hang et al, 2011), and label azide- or alkyne-modified nucleic acids. The CuAAC reaction proceeds at considerably faster rates than the Staudinger ligation (more than 25-fold) and is usually 10–100 times faster than copper-free strain-promoted azide-alkyne cycloaddition (discussed below) (Jewett et al, 2010; Presolski et al, 2010), with second-order rate constants of 10–200 M −1 s −1 in the presence of 20–500 μM Cu I .…”

Design of virus-based nanomaterials for medicine, biotechnology, and energy

“…Atom-transfer radical polymerization (ATRP) is one such method, where small initiators can be added to the particles first then polymerization from the capsid carried out through the introduction of monomers, resulting in easier purification of the smaller reagents as well as overcoming challenges with steric hindrance of large bulky polymers. 33, 104, 105 Incorporation of polymers using this method has proven to useful for the attachment or complexation of large payloads of MR contrast agents, chemotherapeutics, and siRNA and for both interior 33, 104 and exterior 105 modification. Polymers could also be synthesized first with ATRP before attachment to the viral capsid, such as for the display of glycoproteins.…”

“…Retention of the molecules inside the capsid can then be achieved through electrostatic and/or affinity interactions with the nucleic acid within the shell 93, 110, 111 or interactions with polymers conjugated internally. 33, 104 Encapsulation of molecules can also be accomplished by gating using pH or metal ion concentration to trigger structural transitions. Using the gating process, molecules are allowed to diffuse into the particle under an environment where the capsid is in a swollen, open conformation, and then the molecules are trapped within the capsid as the pores are closed off through change in buffer conditions.…”

Surface-initiated controlled radical polymerizations from silica nanoparticles, gold nanocrystals, and bionanoparticles

“…The growth of the cationic polymer PDMAEMA resulted in increased binding of the VLP polymer conjugates to cells. 385 Small molecules of interest can be linked to amine groups of PAEMA leading to a very high labeling degree of a VLP. 387 A copolymerization with functional Ru 2+ complexes equipped the particles with a photoactive group being promising for photocatalysis.…”