Density functional theory study on the interactions of L-cysteine with graphene: adsorption stability and magnetism.
Understanding the interactions between graphene and biomolecules is of fundamental relevance to the area of nanobiotechnology. Herein, we take l-cysteine as the probe biomolecule and investigate its adsorption on pristine graphene and B-, N-, Al-, Ni-, Ga-, Pd-doped graphene using density functional theory calculations. Three kinds of upright adsorption configurations, via unprotonated functional groups (-SH, -NH2, -COOH), are considered. The calculations reveal pristine graphene physically adsorbs l-cysteine. N-doped graphene shows physisorption towards the S-end and N-end l-cysteine, and chemisorption towards the O-end radical. Strong chemisorption, with site-specific preference, occurs on Al-, Ni-, Ga- and Pd-doped graphene, accompanied by severe structural changes. Spin polarization with an unusual mirror symmetry on Ni- and Pd-doped graphene is induced by chemisorption of unprotonated l-cysteine, except for O-end adsorption on Pd-doped graphene. The magnetization arises mainly from spin polarization of the C 2pz orbital, with a minor magnetism located on Ni or Pd. The influence of van der Waals forces is also evaluated. A thorough analysis of the adsorption stability and magnetism of these systems would be beneficial to facilitate applications in graphene-based biosensing, biomolecule immobilization, magnetic bio-separation and other fields in bionanotechnology.
State Key Laboratory of Solidification Processing, Carbon/Carbon Composites Research Center, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China.
Huijuan
H
Luo
Hejun
H
Li
Qiangang
Q
Fu
Yanhui
Y
Chu
Xiaoyu
X
Cao
Can
C
Sun
Xiaoyan
X
Yuan
Lei
L
Liu
D000327:Adsorption; D000535:Aluminum / Q000737:chemistry; D001709:Biotechnology; D003198:Computer Simulation; D003545:Cysteine / Q000737:chemistry*; D005609:Free Radicals; D005708:Gallium / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D008280:Magnetics; D036103:Nanotechnology; D009532:Nickel / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D013499:Surface Properties
D005609:Free Radicals; D010165:Palladium; D006108:Graphite; D009532:Nickel; D005708:Gallium; D000535:Aluminum; D003545:Cysteine