Sound-driven dissipative self-assembly of aromatic biomolecules into functional nanoparticles

Abstract

The out-of-equilibrium self-assembly of simple aromatic amino acid molecules is driven by high frequency ultrasound, where acoustic energy acts as a fuel to form uniform supramolecular nanostructures with multifarious optical and biological properties.

Sono-Assembly of the [Arg-Phe]4 Octapeptide into Biofunctional Nanoparticles

“…The alternating arginine-phenylalanine [RF] 4 octapeptide tends to self-assemble and forms β -sheet amyloidal fibrils with different amyloidal analogues [ 28 ] at a concentration of 0.17 wt.%. The transmittance peaks at 1670 cm −1 and 1633 cm −1 shown in Figure S2 indicate the β -sheet secondary structural conformation of the octapeptide.…”

“…The cac of the peptides in millipore water was found to be 1 mM (1.26 mg/mL or 0.126 wt.%) from the plot shown in Figure 1 a. [ 28 ]. When dissolved in water at a concentration of 0.4 mM (below cac ), the [RF] 4 octapeptide exhibited emission peaks at 435, 565, and 620 nm, as shown in Figure 1 b.…”

“…When dissolved in water at a concentration of 0.4 mM (below cac ), the [RF] 4 octapeptide exhibited emission peaks at 435, 565, and 620 nm, as shown in Figure 1 b. As phenylalanine does not exhibit any fluorescence in the wavelength range of 400–700 nm, the emission peak at 435 nm was attributed to intramolecular π-π interactions between the phenylalanine moieties, whereas the emissions at wavelengths >565 nm might be due to cation-π interactions between the NH + group of arginine and the phenyl ring of the phenylalanine [ 28 ]. We performed the sonication of the [RF] 4 octapeptide at a concentration of 1 mg/mL, below the cac , in order to rule out any possibility of aggregation before sonication.…”

“…[RF] 4 octapeptides ( Figure S1 ) were synthesized in our lab [ 28 ]. We procured 1-diphenyl-2-picrylhydrazyl (DPPH), Dulbecco’s phosphate-buffered saline (D-PBS), bovine serum albumin (BSA), hydrogen peroxide (30%), and EIPA (ethylisopropyl amiloride) from Sigma Aldrich (St. Louis, MO, USA).…”

“…Herein, we report on the effect of high-frequency ultrasound treatment on aqueous solutions of self-assembling oligopeptides. Alves and coworkers [ 28 , 29 ] have extensively explored the spontaneous self-assembly of [RF] 4 octapeptides comprising arginine (R) and phenylalanine (F) in an alternating sequence. The [RF] 4 octapeptides can form interconnected nanofibrillar structures rich in β-sheet structures, as well as other oligomeric species by self-assembly via the solid-vapor phase method.…”