Facile and versatile method to achieve 3D arrangement of nanoparticles remain as a challenge for nanoscientists. On the other hand, self-assembly process is widely found in nature. Here, we present 3D self-assembled structure of nanoparticles using protein crystals as a template. Controlling directed self-assembly of nanoparticles requires understanding interactions between nanoscale building blocks. In this study, we controlled interaction between gold nanoparticles (AuNPs) and hen egg white lysozyme (HEWL) and achieved 3D assembly of AuNPs incorporated in protein crystals. When gold nanoparticles are functionalized with large poly (ethylene glycol) (PEG), weak attractive interaction between AuNPs and HEWL arises. This weak interaction leads to facilitate nucleation of HEWL crystals and incorporation of gold nanoparticles into HEWL crystals. SAXS and TEM data shows that AuNPs were incorporated into lysozyme crystals and AuNPs inside the crystals have some ordered arrangement within crystal structure. The kinetics of nucleation and distribution coefficient of AuNPs in protein crystals were studied. The phenomenon was independent of nanoparticle type and we found other nanoparticles, such as iron oxide, quantum dots and gold nanorods also occurred if the surface grafting density of PEG was low. This confirms that the surface properties of NP-PEG conjugates, rather than the nanoparticle itself, dictates the protein-nanoparticle solution interactions and the subsequence incorporation of nanoparticles into biomolecular crystals.

Self-assembly of nanoparticles via co-crystallization with proteins

253rd National Meeting (2017)

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