Layer‐by‐Layer Fabrication and Characterization of Gold‐Nanoparticle/Myoglobin Nanocomposite Films

Abstract

Multilayer thin films of ∼ 7 nm diameter gold nanoparticles (GNPs) linked with horse heart myoglobin (Mb) are fabricated, for the first time, by layer‐by‐layer (LbL) assembly on glass slides, and silicon and plastic substrates. The GNP/Mb nanocomposite films show sharp surface plasmon resonance (SPR) absorption bands that are used to follow the LbL growth of the film and to determine the kinetics of GNP adsorption on the Mb‐modified surface. The GNP/Mb nanocomposite films are characterized using atomic force microscopy, transmission electron microscopy, polarized UV‐vis spectroscopy, and spectroscopic ellipsometry. The GNPs in the multilayer films are spatially separated from one another, and interparticle interactions remain in the film, making it optically anisotropic. The GNP/Mb nanocomposite films are stable in air at temperatures up to 100 °C, and can withstand successive immersions in strongly acidic and basic solutions. The SPR absorption band of the GNP/Mb nanocomposite film in air exhibits a red‐shift in the wavelength maximum and an increase in the maximum absorbance relative to that in water. This result, which is in contrast to that observed with a GNP monolayer on an aminosilane‐functionalized substrate, suggests the shrinkage in air and swelling in water of Mb molecules embedded in the nanocomposite film.

Layer-by-layer fabrication of well-packed gold nanoparticle assemblies guided by a β-sheet peptide network

“…The absorption maxima of these bands (l max ) were fixed at a wavelength of 542 nm and did not change with the number of dipping cycles. Previous reports [21][22][23][24][25][26][27] have pointed out that in multilayer gold nanoparticles, strong interactions between neighboring dipolar particles can readily take place, which cause a red shift in l max with increasing number of dipping cycles and/or generate a new absorption band at a longer wavelength. In our case, however, no such features appear in the spectra, as shown in Figure 2, suggesting that the gold nanoparticles in films are spatially separated from each other, probably because of the long PLGA chains attached to the gold nanoparticles, and that the interparticle interactions are relatively weak.…”

“…The LbL assembly takes advantage of the same attractive forces that form complexes but in a controlled manner that produces thin, conformal films that can coat a variety of surfaces and thus are a powerful method for fabricating multilayer gold nanoparticle films. [15][16][17][18][19][20][21][22][23][24][25][26][27] In spite of these many reports, to the best of our knowledge, well-controlled gold nanoparticle assemblies guided with a polypeptide network have not yet been reported. The aim of this article is to construct homogeneously well-ordered gold nanoparticle multilayers assisted with a b-sheet peptide template.…”

Thin Films Composed of Multiwalled Carbon Nanotubes, Gold Nanoparticles and Myoglobin for Humidity Detection at Room Temperature

“…[20] In the presence of the electrostatic attraction between GNPs and Mb-modified MWCNTs, partially transparent and conductive CNT/GNP/Mb nanocomposite thin films can be formed on top of glass slide substrates from the mixed solution. Our previous work has demonstrated that the size of Mb molecules is sensitive to ambient humidity at room temperature (RT).…”

“…[11][12][13][14][15] We recently presented a myoglobin (Mb)-linked GNP multilayer film-based sensor with an LSPR sensitivity to humidity arising from induced changes in the interparticle spacing rather than changes in refractive index or adlayer thickness. [17] Since the electrical conductivity of the Mb-linked GNP multilayer film is too small to be easily measurable, [20] the sensor is not compatible with electrical signals. To enable the humidity sensor to operate with either an optical or an electrical signal, or both, optically transparent and electrically conductive thin films of CNT/GNP/Mb nanocomposite were fabricated on glass substrates by incorporating MWCNTs into an Mb-linked GNP network.…”

“…[11][12][13][14][15][16][17] The LSPR spectrum for GNP thin films relies on several parameters, including the particle size and shape, the refractive index of the surrounding media, the thickness of the cover layer, and the interparticle spacing. [11][12][13][14][15][16][17][18][19][20] Conventional GNPbased sensors operate by manipulating the effects of the surrounding refractive index and (or) adlayer thickness on the LSPR behavior of the sensor. [11][12][13][14][15] We recently presented a myoglobin (Mb)-linked GNP multilayer film-based sensor with an LSPR sensitivity to humidity arising from induced changes in the interparticle spacing rather than changes in refractive index or adlayer thickness.…”