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Systematic Screening and Deep Analysis of CoPt Binding Peptides Leads to Enhanced CoPt Nanoparticles Using Designed Peptides
journal contribution
posted on 2020-08-03, 18:04 authored by Rosie
M. Jarrald, Aw W. Liang Alvin, Andrea E. Rawlings, Masayoshi Tanaka, Mina Okochi, Sarah S. StanilandUsing
protein and peptide additives to direct the crystallization
of inorganic materials is a very attractive and environmentally friendly
strategy to access complex and sometimes inaccessible mineral phases.
CoPt is a very desirable high-magnetoanisotropic material in its L10 phase, but this is acquired by annealing at high temperatures
which is incompatible with delicate nanomaterial assembly. Previous
studies identified one peptide with high affinity to CoPt and four
peptides with high affinity to FePt L10 phase nanoparticles
(NPs) through phage display biopanning selection. While synthesis
mediated by these peptides offered a small degree of L10 character to the NPs, they do not have the magnetoanistropy required
for applications. In this study, we improve the activity of peptide
directed crystallization by designing second generation peptides.
We use the five literature sequences (LS) to probe the binding affinity
deeper through dissection (alanine scanning), reduction (truncations),
and substitution of the LS to find key amino acids and motifs. This
is performed using a SPOT peptide array, importantly probing interactions
at three stages of NP formation: with precursor, during synthesis,
and with NPs. We found four universal features: 1) the importance
of basic residues, particularly lysine flanking both ends of the sequence;
2) the importance of methionine; 3) shorter sequences show higher
affinity than longer ones; and 4) acidic residues have a negative
impact on binding with aspartic acid less favorable than glutamic
acid. However, an acidic amino acid benefits, presumably to balance
charge. The short motif KSLS had high affinity in all assays. Three
sequences were selected from the screening, and three sequences were
designed from the rules above. These were used to mediate a green
synthesis of CoPt nanoparticles. The screened peptides mediated the
formation of NPs with improved coercivity (90–110 Oe) compared
to the LS (30–80 Oe), while the designed peptides facilitated
formation of CoPt NPs with the highest coercivity (109 to 132 Oe),
representing a massive improvement on L10 character. This
result along with deeper insight this methodology brings offers vast
potential for the future.
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Previous studiesgeneration peptidesL 1 0 phaseDeep Analysissequences showhigh-magnetoanisotropic materialFePt L 1 0 phase nanoparticlesliterature sequencesbalance chargeSystematic ScreeningCoPt Binding Peptidesnanomaterial assemblyCoPt nanoparticlespeptide additivesbinding affinityNP formationmotif KSLSmineral phasesSPOT peptide arrayCoPt NPsEnhanced CoPt Nanoparticlesphage display biopanning selectionL 1 0 characteracid benefitsaspartic acid
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