We provide strong chemical and biophysical evidence that documents that branched amphiphilic peptides, BAPs, known to assemble into spherical nanoassemblies in solution, do assemble as peptide-bilayer-delimited capsules. These nanoassemblies are termed branched amphiphilic peptide capsules (BAPCs). BAPCs are taken up by cells and accumulate in the perinuclear region to persist there without apparent degradation. BAPCs also entrap small proteins and solutes and stably encapsulate α-particle-emitting radionuclides. We have devised a method utilizing thiol chemistry to conjugate these peptide sequences onto gold nanoparticles (≤5 nm) with the objective of demonstrating the assembly of these peptides into a bilayer. The peptides are initially assembled as a monolayer on the gold surface via interaction with cysteine residues on the peptide C-terminus in an organic solvent. The subsequent transition of these peptide-monolayer-protected gold nanoparticles to an aqueous solution in the presence of excess peptides led to the formation of the peptide bilayer on the gold surface. The approach was exploited further to produce bilayer-coated magnetic nanoparticles. The innovation described in this study provides a stable metallic nanoparticle–peptide conjugate system that will help to determine interactions of BAPs in a biological system, with relative ease, important for developing future applications such as simultaneous delivery and imaging of surface-bound molecules of interest.

中文翻译：

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多功能支链两亲性肽双层共轭金纳米粒子的合成与表征

我们提供有力的化学和生物物理证据，证明分支的两亲性肽BAP（已知在溶液中组装成球形纳米组装件）确实以肽-双层分隔的胶囊组装。这些纳米组件称为分支两亲肽胶囊（BAPC）。BAPC被细胞吸收并积聚在核周区域中，以在那里持续存在而没有明显的降解。BAPC还捕获小蛋白质和溶质，并稳定地包裹发射α粒子的放射性核素。我们设计了一种方法，利用硫醇化学将这些肽序列缀合到金纳米颗粒（≤5nm）上，目的是证明这些肽组装成双层。通过与有机溶剂中的肽C端上的半胱氨酸残基相互作用，这些肽最初在金表面上组装为单层。这些肽单层保护的金纳米颗粒随后在过量肽存在下向水溶液的转变导致在金表面上形成肽双层。该方法被进一步开发以生产双层涂层的磁性纳米颗粒。这项研究中描述的创新技术提供了一个稳定的金属纳米颗粒-肽共轭体系，该体系相对容易地有助于确定BAP在生物系统中的相互作用，这对于开发未来的应用（例如同时递送和对感兴趣的表面结合分子进行成像）至关重要。这些肽单层保护的金纳米颗粒随后在过量肽存在下向水溶液的转变导致在金表面上形成肽双层。该方法被进一步开发以生产双层涂层的磁性纳米颗粒。这项研究中描述的创新技术提供了一个稳定的金属纳米颗粒-肽共轭体系，该体系将相对轻松地帮助确定生物系统中BAP的相互作用，这对于开发未来的应用（例如同时递送和对感兴趣的表面结合分子进行成像）具有重要意义。这些肽单层保护的金纳米颗粒随后在过量肽存在下向水溶液的转变导致在金表面上形成肽双层。该方法被进一步开发以生产双层涂层的磁性纳米颗粒。这项研究中描述的创新技术提供了一个稳定的金属纳米颗粒-肽共轭体系，该体系将相对轻松地帮助确定生物系统中BAP的相互作用，这对于开发未来的应用（例如同时递送和对感兴趣的表面结合分子进行成像）具有重要意义。