Confinement Effect of Organic Nanotubes Toward Green Fluorescent Protein (GFP) Depending on the Inner Diameter Size

Abstract

Transportation, release behavior, and stability of a green fluorescent protein (GFP, 3x4 nm) in self-assembled organic nanotubes with three different inner diameters (10, 20, and 80 nm) have been studied in terms of novel nanocontainers. Selective immobilization of a fluorescent acceptor dye on the inner surface enabled us to not only visualize the transportation of GFP in the nanochannels but to also detect release of the encapsulated GFP to the bulk solution in real time, based on fluorescence resonance energy transfer (FRET). Obtained diffusion constants and release rates of GFP markedly decreased as the inner diameter of the nanotubes was decreased. An endo-sensing procedure also clarified the dependence of the thermal and chemical stabilities of the GFP on the inner diameters. The GFP encapsulated in the 10 nm nanochannel showed strong resistance to heat and to a denaturant. On the other hand, the 20 nm nanochannel accelerated the denaturation of the encapsulated GFP compared with the rate of denaturation of the free GFP in bulk and the encapsulated GFP in the 80 nm nanochannels. The confinement effect based on rational fitting of the inner diameter to the size of GFP allowed us to store it stably and without denaturation under high temperatures and high denaturant concentrations.

Analysis of Distribution and Intraparticle Diffusion of a Fluorescent Dye in Mesoporous Silica Gel by Confocal Fluorescence Microspectroscopy

“…High functionality of the porous material is caused by a high specific surface area, interaction between a solute and adsorption sites of the pore walls, effective mass transfer of the solute in the pores, and so forth. [1][2][3] Quantitative analyses of adsorption/desorption and reaction at solid/liquid interfaces, diffusion in the pore solution (pore diffusion) and at the pore walls (surface diffusion), and mass transfer of the solute between the material surface and the bulk solution phase (external mass transfer) in porous material/ solution systems have been demonstrated by chromatographic analysis for a large number of microparticles, 4,5 microspectroscopic analysis for individual microparticles, [6][7][8][9][10][11] and so on. [12][13][14] Nonetheless, detailed consideration will be required for analysis of individual elementary processes because various processes are included in the porous material/solution systems.…”

External and Intraparticle Diffusion of Coumarin 102 with Surfactant in the ODS-silica Gel/water System by Single Microparticle Injection and Confocal Fluorescence Microspectroscopy

“…[1][2][3][4] The mass transfer in the porous material/solution system has been often analyzed in terms of diffusion in pores of the material. [5][6][7][8][9][10] However, analysis of the mass transfer mechanism is generally difficult. As an example, mass transfer in a porous particle/ solution system consists of several elementary processes such as adsorption/desorption at the pore walls, mass transfer in the surrounding solution (external mass transfer), and diffusion in the pore solution (pore diffusion) and along the pore walls (surface diffusion).…”

“…Direct measurements of the individual elementary processes are necessary for the analysis of the mass transfer mechanism in the porous material/solution system. 5,6,9,11,12 Mass transfer of a dye between a porous microparticle and the surrounding solution phase was analyzed by single microparticle injection and absorption microspectroscopy. 6,13 In the single microparticle/solution system, external mass transfer between the microparticle and the bulk solution is steady-state spherical diffusion so that analysis of the external mass transfer is simplified.…”

Produced Water Treatment Using Self-assembled Organic Nanotubes as Adsorbents

“…Self-assembled organic nanotubes (ONTs) can adsorb hydrophobic molecules and heavy metals. Hydrophobic molecules are trapped in the bilayer membrane of the ONTs 14), 15) , whereas heavy metals are trapped on their surfaces 16),17) (Fig. 1).…”