Controlled growth of aligned α-helical-polypeptide brushes for tunable electrical conductivity

Wu, Jia-Rong; Chen, Chia Chun; Chen, Kuei‐Hsien; Chang, Ying

doi:10.1063/1.3560452

Cited by 14 publications

(13 citation statements)

References 28 publications

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“…Subsequently, a processing step called “solvent quenching” was applied to enhance PBLG orientational order and aggregation . Mixed brush samples were first immersed in chloroform, a good solvent for PBLG to cause the chains to stand up before immediately transferring the samples into acetone, a bad solvent for PBLG so that the PBLG brushes would aggregate to minimize contact with acetone, thereby freezing any vertical orientation of PBLG brushes (Figure A). , After solvent quenching, a dramatic change in thickness was observed for all the samples (Figure B). However, the change in thickness was less significant for an increase in thickness of PMMA brushes, indicating a smaller change in the angle between the α-helix rod and the substrate.…”

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confidence: 99%

“…Previous studies reported an almost perpendicular orientation of PBLG brushes after solvent quenching. 18,20 Thus, we assume that the final thickness of PBLG homopolymer brushes (sample I, 235 nm) after solvent quenching should be nearly equal to the length of the PBLG brushes. As each monomer unit contributes 1.5 Å along the helical axis of the chain to the final length of PBLG brushes, the degree of polymerization was about 1500.…”

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confidence: 99%

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Synthesis, Processing, and Characterization of Helical Polypeptide Rod–Coil Mixed Brushes

2018

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Mixed polymer brushes of rod-type polypeptide and coiltype vinyl polymer brushes were synthesized via two sequential steps of vapor deposition surface-initiated ring-opening polymerization (SI-ROP) and surface-initiated atom transfer radical polymerization (SI-ATRP), respectively. The effect on polypeptide brushes by coil-type brushes of their surface morphology, film thickness, and orientation were investigated before and after solvent quenching processes using chloroform and acetone. Before solvent quenching, the as-grown coil-type brushes forced the polypeptide brushes to stand up from the surface, resulting in higher film thickness, but the polypeptide brushes remained randomly oriented. After solvent quenching, polypeptide brushes tended to aggregate into conical bundles with an orientation perpendicular to the substrate, but coil-type brushes restricted the free arrangement of the polypeptide brushes and lessen their upward movement. Changes in film thickness, rod orientation, morphology, and wettability were observed with increased molecular weight of the coil-type polymer in the mixed brushes.

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confidence: 99%

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confidence: 99%

Synthesis, Processing, and Characterization of Helical Polypeptide Rod–Coil Mixed Brushes

2018

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“…In this case, the force acting between the probe and the molecules can be controlled and the measurement can be performed at near equilibrium conditions avoiding significant deformation of the molecules entrapped within the junction. Such approach was demonstrated by Wu et al who studied current–voltage response of the junctions incorporating aligned α‐helical polypeptide brushes 55. They found a very high rectification ratio reaching up to 122.…”

Section: Electron Transfer Properties Of Peptide Molecular Junctionsmentioning

confidence: 97%

Review peptides and proteins wired into the electrical circuits: An SPM‐based approach

Sęk

2013

Biopolymers

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Development of molecular scale electronics stimulates the search for new functional materials and compounds. One of the promising directions of further growth within this field is bioelectronics, which assumes the use of electron transfer (ET)-mediating properties of bio-related compounds. Because of the structural and functional versatility, peptides and proteins are particularly well suited to perform as single-molecule-based elements of circuits or sensing devices. In this review, it is demonstrated that purposely designed systems such as molecular junctions are excellent platforms for the studies of ET properties of peptides and proteins at nanoscale level. Using experimental approach based on scanning probe microscopy, individual molecules can be directly wired between two metallic contacts, and their conductance can be determined. ET behavior of the peptides and proteins can be analyzed in terms of their applicability as molecular wires, switches, diodes and elements of sensing devices.

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“…The origin of the screw-sense inversion was attributed to small changes in the strength of the dipole–dipole interactions between the amide backbone and ester side chains induced by the solvent vapor. Of particular relevance to our study, Wang et al , reported that the orientations of surface-grafted PBLG chains can be switched via “solvent quenching”, a process wherein a grafted brush is first swollen with a good solvent such as chloroform, rapidly transferred into a poor solvent for PBLG such as acetone and then dried. The process results in the formation of teepee-like assemblies comprising clusters of PBLG chains.…”

Section: Introductionmentioning

confidence: 93%

Using Liquid Crystals to Probe the Organization of Helical Polypeptide Brushes Induced by Solvent Pretreatment

et al. 2021

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Grafted polymer brushes form the basis of a versatile class of surfaces with properties that can be tailored via choice of the chemical functional groups or architecture of the grafted polymers. Here, we explore how treatment by solvents can program the organization of homopolymer brushes comprising helical poly(γ-benzyl-Lglutamate) (PBLG) and how the orientational behavior of liquid crystals (LCs) contacted with the brushes can provide fresh insights into brush organization. We treated PBLG brushes with either good (chloroform) or poor (acetone) solvents to form collapsed or teepee-like grafted polymer organizations, respectively. When supported on PBLG brushes with thicknesses [determined by atomic force microscopy (AFM)] of 50 nm, we found that collapsed and teepee-like brushes induced planar (parallel to surface) and homeotropic (perpendicular to surface) orientations of nematic LCs, respectively. By preparing solvent-pretreated brushes with a range of thicknesses (12−140 nm), and by combining insights based on AFM, Fourier-transform infrared spectroscopy and LCs, we found that a continuous change in tilt of the LC is accompanied by a continuous change in tilt of the PBLG chains, as influenced by the teepee-like organization. The role of PBLG chain orientation in dictating the LC orientation was confirmed by additional experiments in which PBLG brushes were thermally denatured. Finally, when using mixed solvents (mixtures of chloroform and acetone) to manipulate the PBLG brush organization, we observed LCs to exhibit patterned orientations on the micrometer scale, consistent with patterned orientations of the PBLG chains imprinted by droplets formed during the mixed solvent drying process. Overall, these results expand our understanding of the range of PBLG brush organizations that can be induced by solvent pretreatment and demonstrate the utility of LCs for imaging PBLG chain orientation within brushes.

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Controlled growth of aligned α-helical-polypeptide brushes for tunable electrical conductivity

Cited by 14 publications

References 28 publications

Synthesis, Processing, and Characterization of Helical Polypeptide Rod–Coil Mixed Brushes

Synthesis, Processing, and Characterization of Helical Polypeptide Rod–Coil Mixed Brushes

Review peptides and proteins wired into the electrical circuits: An SPM‐based approach

Using Liquid Crystals to Probe the Organization of Helical Polypeptide Brushes Induced by Solvent Pretreatment

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