Conformational Change Induced Reversible Assembly/Disassembly of Poly-l-lysine-Functionalized Gold Nanoparticles

Abstract

The poly-l-lysine-functionalized gold nanoparticle (PLL-GNP) was found to undergo reversible assembly/disassembly in the range of pH from 6.5 to 11.0 at room temperature. At a high pH value, the deprotonated lysine residues allow the formation of α-helix and β-sheet structures at the expense of a part of random coil and β-turn structures, thus inducing the assembly of GNPs. With a decrease of pH to 6.5, the assembly of GNPs is disrupted due to the conversion of the α-helix and β-sheet back into the random and β-turn. It is identified that the formation/collapse of an antiparallel β-sheet structure among PLL chains from adjacent GNPs is responsible for reversible pH-dependent assembly/disassembly of GNPs. Since the conformation-induced assembly/disassembly process of the PLL-GNP can be well recognized by a shift of the surface plasmon resonance band of the GNP and the color change of the solution, this study presents the possibility of following the conformation change of a peptide by monitoring the spectral change of the GNP.

Bioremediation of Refinery Oil Contaminated Soil

“…The remediation of contaminated soil includes physical, chemical and biological ways at present [4] [5] [6]. The biological ways includes microbial remediation, phytoremediation and microbial phytoremediation [7] [8] [9].…”

Unconventional Assembly of Bimetallic Au–Ni Janus Nanoparticles on Chemically Modified Silica Spheres

“…Usually, the manipulation of assemblies is not possible once they are constructed in solution for all above mentioned examples, and their further manipulation is even more impossible. The isotropic assembly/disassembly process can be induced by DNA strand pairing, [24,25] pH, [26] salt, [27] block copolymers, [28] and UV irradiation. [29] However, reports on anisotropic assembly/disassembly are limited.…”

Double-shell gold nanoparticle-based DNA-carriers with poly-l-lysine binding surface

“…On the basis of CD data, Guo et al [18] have estimated that at pH ¼ 6.5 the content of random coil is 62.9% and the content of bturn is 37.1%, while at pH ¼ 11, the contents of a-helix is 40.9% and that of b-sheet is 21.0% and only 30.3% of PLL remains in the form of the random coil and 7.8% in the form of b-turn. The transition to bsheet, either from random coil at neutral pH or from a-helix at higher pH, can be induced by suspending lipid vesicles (dilauroylphosphatidic acid, DLPA) [19].…”

“…Direct interaction of lysine residues with Au surface stabilizes the gold nanoparticles (AuNP) in solution [20]. However, it has been shown by Guo et al [18] that there is apparently no interparticle interaction between PLL-capped gold nanoparticles in the pH range 6.5e10.5 since only a very small shift of SP absorbance band, from 522 to 526 nm is observed. However, at pH 11.5, a clear aggregation of PLLcapped AuNP has been observed concomitant with a shift in the SP band maximum to l max ¼ 538 nm.…”